Merge branch 'v2-prototype' into bug/contracts/eip712-191-prefix

46 files changed, 1056 insertions, 311 deletions

diff --git a/packages/contracts/src/contracts/current/protocol/AssetProxy/ERC20Proxy.sol b/packages/contracts/src/contracts/current/protocol/AssetProxy/ERC20Proxy.sol
index 2c321e134..eeddb9707 100644
--- a/packages/contracts/src/contracts/current/protocol/AssetProxy/ERC20Proxy.sol
+++ b/packages/contracts/src/contracts/current/protocol/AssetProxy/ERC20Proxy.sol
@@ -34,36 +34,51 @@ contract ERC20Proxy is
     uint8 constant PROXY_ID = 1;
 
     /// @dev Internal version of `transferFrom`.
-    /// @param assetMetadata Encoded byte array.
+    /// @param assetData Encoded byte array.
     /// @param from Address to transfer asset from.
     /// @param to Address to transfer asset to.
     /// @param amount Amount of asset to transfer.
     function transferFromInternal(
-        bytes memory assetMetadata,
+        bytes memory assetData,
         address from,
         address to,
         uint256 amount
     )
         internal
     {
-        // Data must be intended for this proxy.
-        uint256 length = assetMetadata.length;
+        // Decode asset data.
+        address token = readAddress(assetData, 0);
 
+        // Transfer tokens.
+        // We do a raw call so we can check the success separate
+        // from the return data.
+        bool success = token.call(abi.encodeWithSelector(
+            IERC20Token(token).transferFrom.selector,
+            from,
+            to,
+            amount
+        ));
         require(
-            length == 21,
-            LENGTH_21_REQUIRED
-        );
-        // TODO: Is this too inflexible in the future?
-        require(
-            uint8(assetMetadata[length - 1]) == PROXY_ID,
-            ASSET_PROXY_ID_MISMATCH
+            success,
+            TRANSFER_FAILED
         );
-
-        // Decode metadata.
-        address token = readAddress(assetMetadata, 0);
-
-        // Transfer tokens.
-        bool success = IERC20Token(token).transferFrom(from, to, amount);
+        
+        // Check return data.
+        // If there is no return data, we assume the token incorrectly
+        // does not return a bool. In this case we expect it to revert
+        // on failure, which was handled above.
+        // If the token does return data, we require that it is a single
+        // value that evaluates to true.
+        assembly {
+            if returndatasize {
+                success := 0
+                if eq(returndatasize, 32) {
+                    // First 64 bytes of memory are reserved scratch space
+                    returndatacopy(0, 0, 32)
+                    success := mload(0)
+                }
+            }
+        }
         require(
             success,
             TRANSFER_FAILED
diff --git a/packages/contracts/src/contracts/current/protocol/AssetProxy/ERC721Proxy.sol b/packages/contracts/src/contracts/current/protocol/AssetProxy/ERC721Proxy.sol
index 07e01c774..861fac2c1 100644
--- a/packages/contracts/src/contracts/current/protocol/AssetProxy/ERC721Proxy.sol
+++ b/packages/contracts/src/contracts/current/protocol/AssetProxy/ERC721Proxy.sol
@@ -34,47 +34,38 @@ contract ERC721Proxy is
     uint8 constant PROXY_ID = 2;
 
     /// @dev Internal version of `transferFrom`.
-    /// @param assetMetadata Encoded byte array.
+    /// @param assetData Encoded byte array.
     /// @param from Address to transfer asset from.
     /// @param to Address to transfer asset to.
     /// @param amount Amount of asset to transfer.
     function transferFromInternal(
-        bytes memory assetMetadata,
+        bytes memory assetData,
         address from,
         address to,
         uint256 amount
     )
         internal
     {
-        // Data must be intended for this proxy.
-        uint256 length = assetMetadata.length;
-
-        require(
-            length == 53,
-            LENGTH_53_REQUIRED
-        );
-
-        // TODO: Is this too inflexible in the future?
-        require(
-            uint8(assetMetadata[length - 1]) == PROXY_ID,
-            ASSET_PROXY_ID_MISMATCH
-        );
-
         // There exists only 1 of each token.
         require(
             amount == 1,
             INVALID_AMOUNT
         );
-
-        // Decode metadata
-        address token = readAddress(assetMetadata, 0);
-        uint256 tokenId = readUint256(assetMetadata, 20);
-
-        // Transfer token.
-        // Either succeeds or throws.
-        // @TODO: Call safeTransferFrom if there is additional
-        //        data stored in `assetMetadata`.
-        ERC721Token(token).transferFrom(from, to, tokenId);
+    
+        // Decode asset data.
+        (
+            address token,
+            uint256 tokenId,
+            bytes memory receiverData
+        ) = decodeERC721AssetData(assetData);
+
+        // Transfer token. Saves gas by calling safeTransferFrom only
+        // when there is receiverData present. Either succeeds or throws.
+        if (receiverData.length > 0) {
+            ERC721Token(token).safeTransferFrom(from, to, tokenId, receiverData);
+        } else {
+            ERC721Token(token).transferFrom(from, to, tokenId);
+        }
     }
 
     /// @dev Gets the proxy id associated with the proxy address.
@@ -86,4 +77,34 @@ contract ERC721Proxy is
     {
         return PROXY_ID;
     }
+
+    /// @dev Decodes ERC721 Asset data.
+    /// @param assetData Encoded byte array.
+    /// @return proxyId Intended ERC721 proxy id.
+    /// @return token ERC721 token address.
+    /// @return tokenId ERC721 token id.
+    /// @return receiverData Additional data with no specific format, which
+    ///                      is passed to the receiving contract's onERC721Received.
+    function decodeERC721AssetData(bytes memory assetData)
+        internal
+        pure
+        returns (
+            address token,
+            uint256 tokenId,
+            bytes memory receiverData
+        )
+    {
+        // Decode asset data.
+        token = readAddress(assetData, 0);
+        tokenId = readUint256(assetData, 20);
+        if (assetData.length > 52) {
+            receiverData = readBytes(assetData, 52);
+        }
+
+        return (
+            token,
+            tokenId,
+            receiverData
+        );
+    }
 }
diff --git a/packages/contracts/src/contracts/current/protocol/AssetProxy/MixinAssetProxy.sol b/packages/contracts/src/contracts/current/protocol/AssetProxy/MixinAssetProxy.sol
index 5fa33cbef..9032658e7 100644
--- a/packages/contracts/src/contracts/current/protocol/AssetProxy/MixinAssetProxy.sol
+++ b/packages/contracts/src/contracts/current/protocol/AssetProxy/MixinAssetProxy.sol
@@ -28,12 +28,12 @@ contract MixinAssetProxy is
 {
 
     /// @dev Transfers assets. Either succeeds or throws.
-    /// @param assetMetadata Encoded byte array.
+    /// @param assetData Encoded byte array.
     /// @param from Address to transfer asset from.
     /// @param to Address to transfer asset to.
     /// @param amount Amount of asset to transfer.
     function transferFrom(
-        bytes assetMetadata,
+        bytes assetData,
         address from,
         address to,
         uint256 amount
@@ -42,7 +42,7 @@ contract MixinAssetProxy is
         onlyAuthorized
     {
         transferFromInternal(
-            assetMetadata,
+            assetData,
             from,
             to,
             amount
@@ -50,12 +50,12 @@ contract MixinAssetProxy is
     }
 
     /// @dev Makes multiple transfers of assets. Either succeeds or throws.
-    /// @param assetMetadata Array of byte arrays encoded for the respective asset proxy.
+    /// @param assetData Array of byte arrays encoded for the respective asset proxy.
     /// @param from Array of addresses to transfer assets from.
     /// @param to Array of addresses to transfer assets to.
     /// @param amounts Array of amounts of assets to transfer.
     function batchTransferFrom(
-        bytes[] memory assetMetadata,
+        bytes[] memory assetData,
         address[] memory from,
         address[] memory to,
         uint256[] memory amounts
@@ -63,9 +63,9 @@ contract MixinAssetProxy is
         public
         onlyAuthorized
     {
-        for (uint256 i = 0; i < assetMetadata.length; i++) {
+        for (uint256 i = 0; i < assetData.length; i++) {
             transferFromInternal(
-                assetMetadata[i],
+                assetData[i],
                 from[i],
                 to[i],
                 amounts[i]
diff --git a/packages/contracts/src/contracts/current/protocol/AssetProxy/interfaces/IAssetProxy.sol b/packages/contracts/src/contracts/current/protocol/AssetProxy/interfaces/IAssetProxy.sol
index 7e1848889..22f43b12f 100644
--- a/packages/contracts/src/contracts/current/protocol/AssetProxy/interfaces/IAssetProxy.sol
+++ b/packages/contracts/src/contracts/current/protocol/AssetProxy/interfaces/IAssetProxy.sol
@@ -26,12 +26,12 @@ contract IAssetProxy is
 {
 
     /// @dev Transfers assets. Either succeeds or throws.
-    /// @param assetMetadata Byte array encoded for the respective asset proxy.
+    /// @param assetData Byte array encoded for the respective asset proxy.
     /// @param from Address to transfer asset from.
     /// @param to Address to transfer asset to.
     /// @param amount Amount of asset to transfer.
     function transferFrom(
-        bytes assetMetadata,
+        bytes assetData,
         address from,
         address to,
         uint256 amount
@@ -39,12 +39,12 @@ contract IAssetProxy is
         external;
     
     /// @dev Makes multiple transfers of assets. Either succeeds or throws.
-    /// @param assetMetadata Array of byte arrays encoded for the respective asset proxy.
+    /// @param assetData Array of byte arrays encoded for the respective asset proxy.
     /// @param from Array of addresses to transfer assets from.
     /// @param to Array of addresses to transfer assets to.
     /// @param amounts Array of amounts of assets to transfer.
     function batchTransferFrom(
-        bytes[] memory assetMetadata,
+        bytes[] memory assetData,
         address[] memory from,
         address[] memory to,
         uint256[] memory amounts
diff --git a/packages/contracts/src/contracts/current/protocol/AssetProxy/libs/LibAssetProxyErrors.sol b/packages/contracts/src/contracts/current/protocol/AssetProxy/libs/LibAssetProxyErrors.sol
index e0c7fc796..65bdacdb7 100644
--- a/packages/contracts/src/contracts/current/protocol/AssetProxy/libs/LibAssetProxyErrors.sol
+++ b/packages/contracts/src/contracts/current/protocol/AssetProxy/libs/LibAssetProxyErrors.sol
@@ -27,11 +27,6 @@ contract LibAssetProxyErrors {
     string constant AUTHORIZED_ADDRESS_MISMATCH = "AUTHORIZED_ADDRESS_MISMATCH";  // Address at index does not match given target address.
 
     /// AssetProxy errors ///
-    string constant ASSET_PROXY_ID_MISMATCH = "ASSET_PROXY_ID_MISMATCH";          // Proxy id in metadata does not match this proxy id.
     string constant INVALID_AMOUNT = "INVALID_AMOUNT";                            // Transfer amount must equal 1.
-    string constant TRANSFER_FAILED = "TRANSFER_FAILED";                          // Transfer failed. 
-
-    /// Length validation errors ///
-    string constant LENGTH_21_REQUIRED = "LENGTH_21_REQUIRED";                    // Byte array must have a length of 21.
-    string constant LENGTH_53_REQUIRED = "LENGTH_53_REQUIRED";                    // Byte array must have a length of 53.
+    string constant TRANSFER_FAILED = "TRANSFER_FAILED";                          // Transfer failed.
 }
diff --git a/packages/contracts/src/contracts/current/protocol/AssetProxy/mixins/MAssetProxy.sol b/packages/contracts/src/contracts/current/protocol/AssetProxy/mixins/MAssetProxy.sol
index de9d65a53..a52cb56f9 100644
--- a/packages/contracts/src/contracts/current/protocol/AssetProxy/mixins/MAssetProxy.sol
+++ b/packages/contracts/src/contracts/current/protocol/AssetProxy/mixins/MAssetProxy.sol
@@ -26,12 +26,12 @@ contract MAssetProxy is
 {
 
     /// @dev Internal version of `transferFrom`.
-    /// @param assetMetadata Encoded byte array.
+    /// @param assetData Encoded byte array.
     /// @param from Address to transfer asset from.
     /// @param to Address to transfer asset to.
     /// @param amount Amount of asset to transfer.
     function transferFromInternal(
-        bytes memory assetMetadata,
+        bytes memory assetData,
         address from,
         address to,
         uint256 amount
diff --git a/packages/contracts/src/contracts/current/protocol/Exchange/Exchange.sol b/packages/contracts/src/contracts/current/protocol/Exchange/Exchange.sol
index b7b308069..51f99bafa 100644
--- a/packages/contracts/src/contracts/current/protocol/Exchange/Exchange.sol
+++ b/packages/contracts/src/contracts/current/protocol/Exchange/Exchange.sol
@@ -40,11 +40,11 @@ contract Exchange is
     string constant public VERSION = "2.0.1-alpha";
 
     // Mixins are instantiated in the order they are inherited
-    constructor (bytes memory _zrxProxyData)
+    constructor (bytes memory _zrxAssetData)
         public
         MixinExchangeCore()
         MixinMatchOrders()
-        MixinSettlement(_zrxProxyData)
+        MixinSettlement(_zrxAssetData)
         MixinSignatureValidator()
         MixinTransactions()
         MixinAssetProxyDispatcher()
diff --git a/packages/contracts/src/contracts/current/protocol/Exchange/MixinAssetProxyDispatcher.sol b/packages/contracts/src/contracts/current/protocol/Exchange/MixinAssetProxyDispatcher.sol
index 8f9342739..9e0246303 100644
--- a/packages/contracts/src/contracts/current/protocol/Exchange/MixinAssetProxyDispatcher.sol
+++ b/packages/contracts/src/contracts/current/protocol/Exchange/MixinAssetProxyDispatcher.sol
@@ -19,12 +19,14 @@
 pragma solidity ^0.4.24;
 
 import "../../utils/Ownable/Ownable.sol";
+import "../../utils/LibBytes/LibBytes.sol";
 import "./libs/LibExchangeErrors.sol";
 import "./mixins/MAssetProxyDispatcher.sol";
 import "../AssetProxy/interfaces/IAssetProxy.sol";
 
 contract MixinAssetProxyDispatcher is
     Ownable,
+    LibBytes,
     LibExchangeErrors,
     MAssetProxyDispatcher
 {
@@ -80,12 +82,14 @@ contract MixinAssetProxyDispatcher is
     }
 
     /// @dev Forwards arguments to assetProxy and calls `transferFrom`. Either succeeds or throws.
-    /// @param assetMetadata Byte array encoded for the respective asset proxy.
+    /// @param assetData Byte array encoded for the respective asset proxy.
+    /// @param assetProxyId Id of assetProxy to dispach to.
     /// @param from Address to transfer token from.
     /// @param to Address to transfer token to.
     /// @param amount Amount of token to transfer.
     function dispatchTransferFrom(
-        bytes memory assetMetadata,
+        bytes memory assetData,
+        uint8 assetProxyId,
         address from,
         address to,
         uint256 amount
@@ -94,18 +98,10 @@ contract MixinAssetProxyDispatcher is
     {
         // Do nothing if no amount should be transferred.
         if (amount > 0) {
-
-            // Lookup asset proxy
-            uint256 length = assetMetadata.length;
-            require(
-                length > 0,
-                LENGTH_GREATER_THAN_0_REQUIRED
-            );
-            uint8 assetProxyId = uint8(assetMetadata[length - 1]);
+            // Lookup assetProxy
             IAssetProxy assetProxy = assetProxies[assetProxyId];
-
             // transferFrom will either succeed or throw.
-            assetProxy.transferFrom(assetMetadata, from, to, amount);
+            assetProxy.transferFrom(assetData, from, to, amount);
         }
     }
 }
diff --git a/packages/contracts/src/contracts/current/protocol/Exchange/MixinExchangeCore.sol b/packages/contracts/src/contracts/current/protocol/Exchange/MixinExchangeCore.sol
index 42128c92a..0a0f0209a 100644
--- a/packages/contracts/src/contracts/current/protocol/Exchange/MixinExchangeCore.sol
+++ b/packages/contracts/src/contracts/current/protocol/Exchange/MixinExchangeCore.sol
@@ -50,7 +50,7 @@ contract MixinExchangeCore is
 
     ////// Core exchange functions //////
 
-    /// @dev Cancels all orders reated by sender with a salt less than or equal to the specified salt value.
+    /// @dev Cancels all orders created by sender with a salt less than or equal to the specified salt value.
     /// @param salt Orders created with a salt less or equal to this value will be cancelled.
     function cancelOrdersUpTo(uint256 salt)
         external
@@ -108,9 +108,6 @@ contract MixinExchangeCore is
         // Compute proportional fill amounts
         fillResults = calculateFillResults(order, takerAssetFilledAmount);
 
-        // Settle order
-        settleOrder(order, takerAddress, fillResults);
-
         // Update exchange internal state
         updateFilledState(
             order,
@@ -119,6 +116,10 @@ contract MixinExchangeCore is
             orderInfo.orderTakerAssetFilledAmount,
             fillResults
         );
+    
+        // Settle order
+        settleOrder(order, takerAddress, fillResults);
+
         return fillResults;
     }
 
diff --git a/packages/contracts/src/contracts/current/protocol/Exchange/MixinMatchOrders.sol b/packages/contracts/src/contracts/current/protocol/Exchange/MixinMatchOrders.sol
index ed76287e0..517b743fe 100644
--- a/packages/contracts/src/contracts/current/protocol/Exchange/MixinMatchOrders.sol
+++ b/packages/contracts/src/contracts/current/protocol/Exchange/MixinMatchOrders.sol
@@ -14,7 +14,6 @@
 pragma solidity ^0.4.24;
 pragma experimental ABIEncoderV2;
 
-import "../../utils/LibBytes/LibBytes.sol";
 import "./libs/LibMath.sol";
 import "./libs/LibOrder.sol";
 import "./libs/LibFillResults.sol";
@@ -25,7 +24,6 @@ import "./mixins/MSettlement.sol";
 import "./mixins/MTransactions.sol";
 
 contract MixinMatchOrders is
-    LibBytes,
     LibMath,
     LibExchangeErrors,
     MExchangeCore,
@@ -94,14 +92,6 @@ contract MixinMatchOrders is
             rightSignature
         );
 
-        // Settle matched orders. Succeeds or throws.
-        settleMatchedOrders(
-            leftOrder,
-            rightOrder,
-            takerAddress,
-            matchedFillResults
-        );
-
         // Update exchange state
         updateFilledState(
             leftOrder,
@@ -117,6 +107,14 @@ contract MixinMatchOrders is
             rightOrderInfo.orderTakerAssetFilledAmount,
             matchedFillResults.right
         );
+    
+        // Settle matched orders. Succeeds or throws.
+        settleMatchedOrders(
+            leftOrder,
+            rightOrder,
+            takerAddress,
+            matchedFillResults
+        );
 
         return matchedFillResults;
     }
diff --git a/packages/contracts/src/contracts/current/protocol/Exchange/MixinSettlement.sol b/packages/contracts/src/contracts/current/protocol/Exchange/MixinSettlement.sol
index 646d3ed58..29a9c87bd 100644
--- a/packages/contracts/src/contracts/current/protocol/Exchange/MixinSettlement.sol
+++ b/packages/contracts/src/contracts/current/protocol/Exchange/MixinSettlement.sol
@@ -19,6 +19,7 @@
 pragma solidity ^0.4.24;
 pragma experimental ABIEncoderV2;
 
+import "../../utils/LibBytes/LibBytes.sol";
 import "./libs/LibMath.sol";
 import "./libs/LibFillResults.sol";
 import "./libs/LibOrder.sol";
@@ -28,33 +29,26 @@ import "./mixins/MSettlement.sol";
 import "./mixins/MAssetProxyDispatcher.sol";
 
 contract MixinSettlement is
+    LibBytes,
     LibMath,
     LibExchangeErrors,
     MMatchOrders,
     MSettlement,
     MAssetProxyDispatcher
 {
-    // ZRX metadata used for fee transfers.
+    // ZRX address encoded as a byte array.
     // This will be constant throughout the life of the Exchange contract,
     // since ZRX will always be transferred via the ERC20 AssetProxy.
-    bytes internal ZRX_PROXY_DATA;
+    bytes internal ZRX_ASSET_DATA;
+    uint8 constant ZRX_PROXY_ID = 1;
 
-    /// @dev Gets the ZRX metadata used for fee transfers.
-    function zrxProxyData()
-        external
-        view
-        returns (bytes memory)
-    {
-        return ZRX_PROXY_DATA;
-    }
-
-    /// TODO: _zrxProxyData should be a constant in production.
+    /// TODO: _zrxAssetData should be a constant in production.
     /// @dev Constructor sets the metadata that will be used for paying ZRX fees.
-    /// @param _zrxProxyData Byte array containing ERC20 proxy id concatenated with address of ZRX.
-    constructor (bytes memory _zrxProxyData)
+    /// @param _zrxAssetData Byte array containing ERC20 proxy id concatenated with address of ZRX.
+    constructor (bytes memory _zrxAssetData)
         public
     {
-        ZRX_PROXY_DATA = _zrxProxyData;
+        ZRX_ASSET_DATA = _zrxAssetData;
     }
 
     /// @dev Settles an order by transferring assets between counterparties.
@@ -68,26 +62,33 @@ contract MixinSettlement is
     )
         internal
     {
+        uint8 makerAssetProxyId = uint8(popLastByte(order.makerAssetData));
+        uint8 takerAssetProxyId = uint8(popLastByte(order.takerAssetData));
+        bytes memory zrxAssetData = ZRX_ASSET_DATA;
         dispatchTransferFrom(
             order.makerAssetData,
+            makerAssetProxyId,
             order.makerAddress,
             takerAddress,
             fillResults.makerAssetFilledAmount
         );
         dispatchTransferFrom(
             order.takerAssetData,
+            takerAssetProxyId,
             takerAddress,
             order.makerAddress,
             fillResults.takerAssetFilledAmount
         );
         dispatchTransferFrom(
-            ZRX_PROXY_DATA,
+            zrxAssetData,
+            ZRX_PROXY_ID,
             order.makerAddress,
             order.feeRecipientAddress,
             fillResults.makerFeePaid
         );
         dispatchTransferFrom(
-            ZRX_PROXY_DATA,
+            zrxAssetData,
+            ZRX_PROXY_ID,
             takerAddress,
             order.feeRecipientAddress,
             fillResults.takerFeePaid
@@ -107,21 +108,27 @@ contract MixinSettlement is
     )
         internal
     {
+        uint8 leftMakerAssetProxyId = uint8(popLastByte(leftOrder.makerAssetData));
+        uint8 rightMakerAssetProxyId = uint8(popLastByte(rightOrder.makerAssetData));
+        bytes memory zrxAssetData = ZRX_ASSET_DATA;
         // Order makers and taker
         dispatchTransferFrom(
             leftOrder.makerAssetData,
+            leftMakerAssetProxyId,
             leftOrder.makerAddress,
             rightOrder.makerAddress,
             matchedFillResults.right.takerAssetFilledAmount
         );
         dispatchTransferFrom(
             rightOrder.makerAssetData,
+            rightMakerAssetProxyId,
             rightOrder.makerAddress,
             leftOrder.makerAddress,
             matchedFillResults.left.takerAssetFilledAmount
         );
         dispatchTransferFrom(
             leftOrder.makerAssetData,
+            leftMakerAssetProxyId,
             leftOrder.makerAddress,
             takerAddress,
             matchedFillResults.leftMakerAssetSpreadAmount
@@ -129,13 +136,15 @@ contract MixinSettlement is
 
         // Maker fees
         dispatchTransferFrom(
-            ZRX_PROXY_DATA,
+            zrxAssetData,
+            ZRX_PROXY_ID,
             leftOrder.makerAddress,
             leftOrder.feeRecipientAddress,
             matchedFillResults.left.makerFeePaid
         );
         dispatchTransferFrom(
-            ZRX_PROXY_DATA,
+            zrxAssetData,
+            ZRX_PROXY_ID,
             rightOrder.makerAddress,
             rightOrder.feeRecipientAddress,
             matchedFillResults.right.makerFeePaid
@@ -144,7 +153,8 @@ contract MixinSettlement is
         // Taker fees
         if (leftOrder.feeRecipientAddress == rightOrder.feeRecipientAddress) {
             dispatchTransferFrom(
-                ZRX_PROXY_DATA,
+                zrxAssetData,
+                ZRX_PROXY_ID,
                 takerAddress,
                 leftOrder.feeRecipientAddress,
                 safeAdd(
@@ -154,13 +164,15 @@ contract MixinSettlement is
             );
         } else {
             dispatchTransferFrom(
-                ZRX_PROXY_DATA,
+                zrxAssetData,
+                ZRX_PROXY_ID,
                 takerAddress,
                 leftOrder.feeRecipientAddress,
                 matchedFillResults.left.takerFeePaid
             );
             dispatchTransferFrom(
-                ZRX_PROXY_DATA,
+                zrxAssetData,
+                ZRX_PROXY_ID,
                 takerAddress,
                 rightOrder.feeRecipientAddress,
                 matchedFillResults.right.takerFeePaid
diff --git a/packages/contracts/src/contracts/current/protocol/Exchange/MixinSignatureValidator.sol b/packages/contracts/src/contracts/current/protocol/Exchange/MixinSignatureValidator.sol
index 48a0c5552..1a556dfe2 100644
--- a/packages/contracts/src/contracts/current/protocol/Exchange/MixinSignatureValidator.sol
+++ b/packages/contracts/src/contracts/current/protocol/Exchange/MixinSignatureValidator.sol
@@ -93,7 +93,7 @@ contract MixinSignatureValidator is
         );
 
         // Pop last byte off of signature byte array.
-        SignatureType signatureType = SignatureType(uint8(popByte(signature)));
+        SignatureType signatureType = SignatureType(uint8(popLastByte(signature)));
 
         // Variables are not scoped in Solidity.
         uint8 v;
@@ -183,7 +183,7 @@ contract MixinSignatureValidator is
         // | 0x14 + x | 1      | Signature type is always "\x06" |
         } else if (signatureType == SignatureType.Validator) {
             // Pop last 20 bytes off of signature byte array.
-            address validator = popAddress(signature);
+            address validator = popLast20Bytes(signature);
             // Ensure signer has approved validator.
             if (!allowedValidators[signer][validator]) {
                 return false;
diff --git a/packages/contracts/src/contracts/current/protocol/Exchange/MixinWrapperFunctions.sol b/packages/contracts/src/contracts/current/protocol/Exchange/MixinWrapperFunctions.sol
index 0ad0710ce..a7849f4cb 100644
--- a/packages/contracts/src/contracts/current/protocol/Exchange/MixinWrapperFunctions.sol
+++ b/packages/contracts/src/contracts/current/protocol/Exchange/MixinWrapperFunctions.sol
@@ -19,7 +19,6 @@
 pragma solidity ^0.4.24;
 pragma experimental ABIEncoderV2;
 
-import "../../utils/LibBytes/LibBytes.sol";
 import "./libs/LibMath.sol";
 import "./libs/LibOrder.sol";
 import "./libs/LibFillResults.sol";
@@ -27,7 +26,6 @@ import "./libs/LibExchangeErrors.sol";
 import "./mixins/MExchangeCore.sol";
 
 contract MixinWrapperFunctions is
-    LibBytes,
     LibMath,
     LibFillResults,
     LibExchangeErrors,
@@ -40,7 +38,8 @@ contract MixinWrapperFunctions is
     function fillOrKillOrder(
         LibOrder.Order memory order,
         uint256 takerAssetFillAmount,
-        bytes memory signature)
+        bytes memory signature
+    )
         public
         returns (FillResults memory fillResults)
     {
@@ -65,7 +64,8 @@ contract MixinWrapperFunctions is
     function fillOrderNoThrow(
         LibOrder.Order memory order,
         uint256 takerAssetFillAmount,
-        bytes memory signature)
+        bytes memory signature
+    )
         public
         returns (FillResults memory fillResults)
     {
@@ -91,12 +91,12 @@ contract MixinWrapperFunctions is
         // |          | 0x0E0  |         |   8.  takerFeeAmount                        |
         // |          | 0x100  |         |   9.  expirationTimeSeconds                 |
         // |          | 0x120  |         |   10. salt                                  |
-        // |          | 0x140  |         |   11. Offset to makerAssetProxyMetadata (*) |
-        // |          | 0x160  |         |   12. Offset to takerAssetProxyMetadata (*) |
-        // |          | 0x180  | 32      | makerAssetProxyMetadata Length              |
-        // |          | 0x1A0  | **      | makerAssetProxyMetadata Contents            |
-        // |          | 0x1C0  | 32      | takerAssetProxyMetadata Length              |
-        // |          | 0x1E0  | **      | takerAssetProxyMetadata Contents            |
+        // |          | 0x140  |         |   11. Offset to makerAssetData (*)          |
+        // |          | 0x160  |         |   12. Offset to takerAssetData (*)          |
+        // |          | 0x180  | 32      | makerAssetData Length                       |
+        // |          | 0x1A0  | **      | makerAssetData Contents                     |
+        // |          | 0x1C0  | 32      | takerAssetData Length                       |
+        // |          | 0x1E0  | **      | takerAssetData Contents                     |
         // |          | 0x200  | 32      | signature Length                            |
         // |          | 0x220  | **      | signature Contents                          |
 
@@ -163,43 +163,45 @@ contract MixinWrapperFunctions is
             mstore(add(dataAreaEnd, 0xE0), mload(add(sourceOffset, 0xE0)))      // takerFeeAmount
             mstore(add(dataAreaEnd, 0x100), mload(add(sourceOffset, 0x100)))    // expirationTimeSeconds
             mstore(add(dataAreaEnd, 0x120), mload(add(sourceOffset, 0x120)))    // salt
-            mstore(add(dataAreaEnd, 0x140), mload(add(sourceOffset, 0x140)))    // Offset to makerAssetProxyMetadata
-            mstore(add(dataAreaEnd, 0x160), mload(add(sourceOffset, 0x160)))    // Offset to takerAssetProxyMetadata
+            mstore(add(dataAreaEnd, 0x140), mload(add(sourceOffset, 0x140)))    // Offset to makerAssetData
+            mstore(add(dataAreaEnd, 0x160), mload(add(sourceOffset, 0x160)))    // Offset to takerAssetData
             dataAreaEnd := add(dataAreaEnd, 0x180)
             sourceOffset := add(sourceOffset, 0x180)
 
-            // Write offset to <order.makerAssetProxyMetadata>
+            // Write offset to <order.makerAssetData>
             mstore(add(dataAreaStart, mul(10, 0x20)), sub(dataAreaEnd, dataAreaStart))
 
-            // Calculate length of <order.makerAssetProxyMetadata>
+            // Calculate length of <order.makerAssetData>
+            sourceOffset := mload(add(order, 0x140)) // makerAssetData
             arrayLenBytes := mload(sourceOffset)
             sourceOffset := add(sourceOffset, 0x20)
             arrayLenWords := div(add(arrayLenBytes, 0x1F), 0x20)
 
-            // Write length of <order.makerAssetProxyMetadata>
+            // Write length of <order.makerAssetData>
             mstore(dataAreaEnd, arrayLenBytes)
             dataAreaEnd := add(dataAreaEnd, 0x20)
 
-            // Write contents of <order.makerAssetProxyMetadata>
+            // Write contents of <order.makerAssetData>
             for {let i := 0} lt(i, arrayLenWords) {i := add(i, 1)} {
                 mstore(dataAreaEnd, mload(sourceOffset))
                 dataAreaEnd := add(dataAreaEnd, 0x20)
                 sourceOffset := add(sourceOffset, 0x20)
             }
 
-            // Write offset to <order.takerAssetProxyMetadata>
+            // Write offset to <order.takerAssetData>
             mstore(add(dataAreaStart, mul(11, 0x20)), sub(dataAreaEnd, dataAreaStart))
 
-            // Calculate length of <order.takerAssetProxyMetadata>
+            // Calculate length of <order.takerAssetData>
+            sourceOffset := mload(add(order, 0x160)) // takerAssetData
             arrayLenBytes := mload(sourceOffset)
             sourceOffset := add(sourceOffset, 0x20)
             arrayLenWords := div(add(arrayLenBytes, 0x1F), 0x20)
 
-            // Write length of <order.takerAssetProxyMetadata>
+            // Write length of <order.takerAssetData>
             mstore(dataAreaEnd, arrayLenBytes)
             dataAreaEnd := add(dataAreaEnd, 0x20)
 
-            // Write contents of  <order.takerAssetProxyMetadata>
+            // Write contents of  <order.takerAssetData>
             for {let i := 0} lt(i, arrayLenWords) {i := add(i, 1)} {
                 mstore(dataAreaEnd, mload(sourceOffset))
                 dataAreaEnd := add(dataAreaEnd, 0x20)
@@ -264,7 +266,8 @@ contract MixinWrapperFunctions is
     function batchFillOrders(
         LibOrder.Order[] memory orders,
         uint256[] memory takerAssetFillAmounts,
-        bytes[] memory signatures)
+        bytes[] memory signatures
+    )
         public
     {
         for (uint256 i = 0; i < orders.length; i++) {
@@ -283,7 +286,8 @@ contract MixinWrapperFunctions is
     function batchFillOrKillOrders(
         LibOrder.Order[] memory orders,
         uint256[] memory takerAssetFillAmounts,
-        bytes[] memory signatures)
+        bytes[] memory signatures
+    )
         public
     {
         for (uint256 i = 0; i < orders.length; i++) {
@@ -303,7 +307,8 @@ contract MixinWrapperFunctions is
     function batchFillOrdersNoThrow(
         LibOrder.Order[] memory orders,
         uint256[] memory takerAssetFillAmounts,
-        bytes[] memory signatures)
+        bytes[] memory signatures
+    )
         public
     {
         for (uint256 i = 0; i < orders.length; i++) {
@@ -323,18 +328,18 @@ contract MixinWrapperFunctions is
     function marketSellOrders(
         LibOrder.Order[] memory orders,
         uint256 takerAssetFillAmount,
-        bytes[] memory signatures)
+        bytes[] memory signatures
+    )
         public
         returns (FillResults memory totalFillResults)
     {
+        bytes memory takerAssetData = orders[0].takerAssetData;
+    
         for (uint256 i = 0; i < orders.length; i++) {
 
-            // Token being sold by taker must be the same for each order
-            // TODO: optimize by only using takerAssetData for first order.
-            require(
-                areBytesEqual(orders[i].takerAssetData, orders[0].takerAssetData),
-                ASSET_DATA_MISMATCH
-            );
+            // We assume that asset being sold by taker is the same for each order.
+            // Rather than passing this in as calldata, we use the takerAssetData from the first order in all later orders.
+            orders[i].takerAssetData = takerAssetData;
 
             // Calculate the remaining amount of takerAsset to sell
             uint256 remainingTakerAssetFillAmount = safeSub(takerAssetFillAmount, totalFillResults.takerAssetFilledAmount);
@@ -346,6 +351,14 @@ contract MixinWrapperFunctions is
                 signatures[i]
             );
 
+            // HACK: the proxyId is "popped" from the byte array before a fill is settled
+            // by subtracting from the length of the array. Since the popped byte is 
+            // still in memory, we can "unpop" it by incrementing the length of the byte array.
+            assembly {
+                let len := mload(takerAssetData)
+                mstore(takerAssetData, add(len, 1))
+            }
+
             // Update amounts filled and fees paid by maker and taker
             addFillResults(totalFillResults, singleFillResults);
 
@@ -366,18 +379,18 @@ contract MixinWrapperFunctions is
     function marketSellOrdersNoThrow(
         LibOrder.Order[] memory orders,
         uint256 takerAssetFillAmount,
-        bytes[] memory signatures)
+        bytes[] memory signatures
+    )
         public
         returns (FillResults memory totalFillResults)
     {
+        bytes memory takerAssetData = orders[0].takerAssetData;
+
         for (uint256 i = 0; i < orders.length; i++) {
 
-            // Token being sold by taker must be the same for each order
-            // TODO: optimize by only using takerAssetData for first order.
-            require(
-                areBytesEqual(orders[i].takerAssetData, orders[0].takerAssetData),
-                ASSET_DATA_MISMATCH
-            );
+            // We assume that asset being sold by taker is the same for each order.
+            // Rather than passing this in as calldata, we use the takerAssetData from the first order in all later orders.
+            orders[i].takerAssetData = takerAssetData;
 
             // Calculate the remaining amount of takerAsset to sell
             uint256 remainingTakerAssetFillAmount = safeSub(takerAssetFillAmount, totalFillResults.takerAssetFilledAmount);
@@ -408,18 +421,18 @@ contract MixinWrapperFunctions is
     function marketBuyOrders(
         LibOrder.Order[] memory orders,
         uint256 makerAssetFillAmount,
-        bytes[] memory signatures)
+        bytes[] memory signatures
+    )
         public
         returns (FillResults memory totalFillResults)
     {
+        bytes memory makerAssetData = orders[0].makerAssetData;
+
         for (uint256 i = 0; i < orders.length; i++) {
 
-            // Token being bought by taker must be the same for each order
-            // TODO: optimize by only using makerAssetData for first order.
-            require(
-                areBytesEqual(orders[i].makerAssetData, orders[0].makerAssetData),
-                ASSET_DATA_MISMATCH
-            );
+            // We assume that asset being bought by taker is the same for each order.
+            // Rather than passing this in as calldata, we copy the makerAssetData from the first order onto all later orders.
+            orders[i].makerAssetData = makerAssetData;
 
             // Calculate the remaining amount of makerAsset to buy
             uint256 remainingMakerAssetFillAmount = safeSub(makerAssetFillAmount, totalFillResults.makerAssetFilledAmount);
@@ -439,6 +452,14 @@ contract MixinWrapperFunctions is
                 signatures[i]
             );
 
+            // HACK: the proxyId is "popped" from the byte array before a fill is settled
+            // by subtracting from the length of the array. Since the popped byte is 
+            // still in memory, we can "unpop" it by incrementing the length of the byte array.
+            assembly {
+                let len := mload(makerAssetData)
+                mstore(makerAssetData, add(len, 1))
+            }
+
             // Update amounts filled and fees paid by maker and taker
             addFillResults(totalFillResults, singleFillResults);
 
@@ -459,18 +480,18 @@ contract MixinWrapperFunctions is
     function marketBuyOrdersNoThrow(
         LibOrder.Order[] memory orders,
         uint256 makerAssetFillAmount,
-        bytes[] memory signatures)
+        bytes[] memory signatures
+    )
         public
         returns (FillResults memory totalFillResults)
     {
+        bytes memory makerAssetData = orders[0].makerAssetData;
+
         for (uint256 i = 0; i < orders.length; i++) {
 
-            // Token being bought by taker must be the same for each order
-            // TODO: optimize by only using makerAssetData for first order.
-            require(
-                areBytesEqual(orders[i].makerAssetData, orders[0].makerAssetData),
-                ASSET_DATA_MISMATCH
-            );
+            // We assume that asset being bought by taker is the same for each order.
+            // Rather than passing this in as calldata, we copy the makerAssetData from the first order onto all later orders.
+            orders[i].makerAssetData = makerAssetData;
 
             // Calculate the remaining amount of makerAsset to buy
             uint256 remainingMakerAssetFillAmount = safeSub(makerAssetFillAmount, totalFillResults.makerAssetFilledAmount);
diff --git a/packages/contracts/src/contracts/current/protocol/Exchange/interfaces/IAssetProxyDispatcher.sol b/packages/contracts/src/contracts/current/protocol/Exchange/interfaces/IAssetProxyDispatcher.sol
index 3ce5ef157..2c331dc34 100644
--- a/packages/contracts/src/contracts/current/protocol/Exchange/interfaces/IAssetProxyDispatcher.sol
+++ b/packages/contracts/src/contracts/current/protocol/Exchange/interfaces/IAssetProxyDispatcher.sol
@@ -28,7 +28,8 @@ contract IAssetProxyDispatcher {
     function registerAssetProxy(
         uint8 assetProxyId,
         address newAssetProxy,
-        address oldAssetProxy)
+        address oldAssetProxy
+    )
         external;
 
     /// @dev Gets an asset proxy.
diff --git a/packages/contracts/src/contracts/current/protocol/Exchange/interfaces/ITransactions.sol b/packages/contracts/src/contracts/current/protocol/Exchange/interfaces/ITransactions.sol
index d973bf001..2f9a5bc7c 100644
--- a/packages/contracts/src/contracts/current/protocol/Exchange/interfaces/ITransactions.sol
+++ b/packages/contracts/src/contracts/current/protocol/Exchange/interfaces/ITransactions.sol
@@ -28,6 +28,7 @@ contract ITransactions {
         uint256 salt,
         address signer,
         bytes data,
-        bytes signature)
+        bytes signature
+    )
         external;
 }
diff --git a/packages/contracts/src/contracts/current/protocol/Exchange/interfaces/IWrapperFunctions.sol b/packages/contracts/src/contracts/current/protocol/Exchange/interfaces/IWrapperFunctions.sol
index 8682b394a..acd4f359c 100644
--- a/packages/contracts/src/contracts/current/protocol/Exchange/interfaces/IWrapperFunctions.sol
+++ b/packages/contracts/src/contracts/current/protocol/Exchange/interfaces/IWrapperFunctions.sol
@@ -33,7 +33,8 @@ contract IWrapperFunctions is
     function fillOrKillOrder(
         LibOrder.Order memory order,
         uint256 takerAssetFillAmount,
-        bytes memory signature)
+        bytes memory signature
+    )
         public
         returns (LibFillResults.FillResults memory fillResults);
 
@@ -46,7 +47,8 @@ contract IWrapperFunctions is
     function fillOrderNoThrow(
         LibOrder.Order memory order,
         uint256 takerAssetFillAmount,
-        bytes memory signature)
+        bytes memory signature
+    )
         public
         returns (LibFillResults.FillResults memory fillResults);
 
@@ -57,7 +59,8 @@ contract IWrapperFunctions is
     function batchFillOrders(
         LibOrder.Order[] memory orders,
         uint256[] memory takerAssetFillAmounts,
-        bytes[] memory signatures)
+        bytes[] memory signatures
+    )
         public;
 
     /// @dev Synchronously executes multiple calls of fillOrKill.
@@ -67,7 +70,8 @@ contract IWrapperFunctions is
     function batchFillOrKillOrders(
         LibOrder.Order[] memory orders,
         uint256[] memory takerAssetFillAmounts,
-        bytes[] memory signatures)
+        bytes[] memory signatures
+    )
         public;
 
     /// @dev Fills an order with specified parameters and ECDSA signature.
@@ -78,7 +82,8 @@ contract IWrapperFunctions is
     function batchFillOrdersNoThrow(
         LibOrder.Order[] memory orders,
         uint256[] memory takerAssetFillAmounts,
-        bytes[] memory signatures)
+        bytes[] memory signatures
+    )
         public;
 
     /// @dev Synchronously executes multiple calls of fillOrder until total amount of takerAsset is sold by taker.
@@ -89,7 +94,8 @@ contract IWrapperFunctions is
     function marketSellOrders(
         LibOrder.Order[] memory orders,
         uint256 takerAssetFillAmount,
-        bytes[] memory signatures)
+        bytes[] memory signatures
+    )
         public
         returns (LibFillResults.FillResults memory totalFillResults);
 
@@ -102,7 +108,8 @@ contract IWrapperFunctions is
     function marketSellOrdersNoThrow(
         LibOrder.Order[] memory orders,
         uint256 takerAssetFillAmount,
-        bytes[] memory signatures)
+        bytes[] memory signatures
+    )
         public
         returns (LibFillResults.FillResults memory totalFillResults);
 
@@ -114,7 +121,8 @@ contract IWrapperFunctions is
     function marketBuyOrders(
         LibOrder.Order[] memory orders,
         uint256 makerAssetFillAmount,
-        bytes[] memory signatures)
+        bytes[] memory signatures
+    )
         public
         returns (LibFillResults.FillResults memory totalFillResults);
 
@@ -127,7 +135,8 @@ contract IWrapperFunctions is
     function marketBuyOrdersNoThrow(
         LibOrder.Order[] memory orders,
         uint256 makerAssetFillAmount,
-        bytes[] memory signatures)
+        bytes[] memory signatures
+    )
         public
         returns (LibFillResults.FillResults memory totalFillResults);
 
diff --git a/packages/contracts/src/contracts/current/protocol/Exchange/libs/LibExchangeErrors.sol b/packages/contracts/src/contracts/current/protocol/Exchange/libs/LibExchangeErrors.sol
index 2b4bbeec4..48dd0f8be 100644
--- a/packages/contracts/src/contracts/current/protocol/Exchange/libs/LibExchangeErrors.sol
+++ b/packages/contracts/src/contracts/current/protocol/Exchange/libs/LibExchangeErrors.sol
@@ -25,7 +25,6 @@ contract LibExchangeErrors {
     string constant INVALID_TAKER = "INVALID_TAKER";                        // Invalid takerAddress.
     string constant INVALID_SENDER = "INVALID_SENDER";                      // Invalid `msg.sender`.
     string constant INVALID_ORDER_SIGNATURE = "INVALID_ORDER_SIGNATURE";    // Signature validation failed. 
-    string constant ASSET_DATA_MISMATCH = "ASSET_DATA_MISMATCH";            // Asset data must be the same for each order. 
     
     /// fillOrder validation errors ///
     string constant INVALID_TAKER_AMOUNT = "INVALID_TAKER_AMOUNT";          // takerAssetFillAmount cannot equal 0.
diff --git a/packages/contracts/src/contracts/current/protocol/Exchange/mixins/MAssetProxyDispatcher.sol b/packages/contracts/src/contracts/current/protocol/Exchange/mixins/MAssetProxyDispatcher.sol
index 87c5f6361..d16a830f4 100644
--- a/packages/contracts/src/contracts/current/protocol/Exchange/mixins/MAssetProxyDispatcher.sol
+++ b/packages/contracts/src/contracts/current/protocol/Exchange/mixins/MAssetProxyDispatcher.sol
@@ -33,12 +33,14 @@ contract MAssetProxyDispatcher is
     );
 
     /// @dev Forwards arguments to assetProxy and calls `transferFrom`. Either succeeds or throws.
-    /// @param assetMetadata Byte array encoded for the respective asset proxy.
+    /// @param assetData Byte array encoded for the respective asset proxy.
+    /// @param assetProxyId Id of assetProxy to dispach to.
     /// @param from Address to transfer token from.
     /// @param to Address to transfer token to.
     /// @param amount Amount of token to transfer.
     function dispatchTransferFrom(
-        bytes memory assetMetadata,
+        bytes memory assetData,
+        uint8 assetProxyId,
         address from,
         address to,
         uint256 amount
diff --git a/packages/contracts/src/contracts/current/test/DummyERC20Token/DummyERC20Token.sol b/packages/contracts/src/contracts/current/test/DummyERC20Token/DummyERC20Token.sol
index 0c7b18c0c..b2fe2df06 100644
--- a/packages/contracts/src/contracts/current/test/DummyERC20Token/DummyERC20Token.sol
+++ b/packages/contracts/src/contracts/current/test/DummyERC20Token/DummyERC20Token.sol
@@ -31,7 +31,8 @@ contract DummyERC20Token is Mintable, Ownable {
         string _name,
         string _symbol,
         uint256 _decimals,
-        uint256 _totalSupply)
+        uint256 _totalSupply
+    )
         public
     {
         name = _name;
diff --git a/packages/contracts/src/contracts/current/test/DummyERC721Receiver/DummyERC721Receiver.sol b/packages/contracts/src/contracts/current/test/DummyERC721Receiver/DummyERC721Receiver.sol
new file mode 100644
index 000000000..c584d0b54
--- /dev/null
+++ b/packages/contracts/src/contracts/current/test/DummyERC721Receiver/DummyERC721Receiver.sol
@@ -0,0 +1,63 @@
+/*
+The MIT License (MIT)
+
+Copyright (c) 2016 Smart Contract Solutions, Inc.
+
+Permission is hereby granted, free of charge, to any person obtaining
+a copy of this software and associated documentation files (the
+"Software"), to deal in the Software without restriction, including
+without limitation the rights to use, copy, modify, merge, publish,
+distribute, sublicense, and/or sell copies of the Software, and to
+permit persons to whom the Software is furnished to do so, subject to
+the following conditions:
+
+The above copyright notice and this permission notice shall be included
+in all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
+OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
+IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
+CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
+TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
+SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+*/
+
+pragma solidity ^0.4.24;
+
+import "../../tokens/ERC721Token/IERC721Receiver.sol";
+
+contract DummyERC721Receiver is
+    IERC721Receiver
+{
+
+    event TokenReceived(
+        address from,
+        uint256 tokenId,
+        bytes data
+    );
+
+    /**
+    * @notice Handle the receipt of an NFT
+    * @dev The ERC721 smart contract calls this function on the recipient
+    *  after a `safetransfer`. This function MAY throw to revert and reject the
+    *  transfer. This function MUST use 50,000 gas or less. Return of other
+    *  than the magic value MUST result in the transaction being reverted.
+    *  Note: the contract address is always the message sender.
+    * @param _from The sending address
+    * @param _tokenId The NFT identifier which is being transfered
+    * @param _data Additional data with no specified format
+    * @return `bytes4(keccak256("onERC721Received(address,uint256,bytes)"))`
+    */
+    function onERC721Received(
+        address _from,
+        uint256 _tokenId,
+        bytes _data
+    )
+        public
+        returns (bytes4)
+    {
+        emit TokenReceived(_from, _tokenId, _data);
+        return ERC721_RECEIVED;
+    }
+}
diff --git a/packages/contracts/src/contracts/current/test/DummyERC721Token/DummyERC721Token.sol b/packages/contracts/src/contracts/current/test/DummyERC721Token/DummyERC721Token.sol
index 369a2950d..5503eb2f2 100644
--- a/packages/contracts/src/contracts/current/test/DummyERC721Token/DummyERC721Token.sol
+++ b/packages/contracts/src/contracts/current/test/DummyERC721Token/DummyERC721Token.sol
@@ -34,7 +34,8 @@ contract DummyERC721Token is
     */
     constructor (
         string name,
-        string symbol)
+        string symbol
+    )
         public
         ERC721Token(name, symbol)
     {}
diff --git a/packages/contracts/src/contracts/current/test/TestAssetDataDecoders/TestAssetDataDecoders.sol b/packages/contracts/src/contracts/current/test/TestAssetDataDecoders/TestAssetDataDecoders.sol
new file mode 100644
index 000000000..5987291d2
--- /dev/null
+++ b/packages/contracts/src/contracts/current/test/TestAssetDataDecoders/TestAssetDataDecoders.sol
@@ -0,0 +1,56 @@
+/*
+
+  Copyright 2018 ZeroEx Intl.
+
+  Licensed under the Apache License, Version 2.0 (the "License");
+  you may not use this file except in compliance with the License.
+  You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+  Unless required by applicable law or agreed to in writing, software
+  distributed under the License is distributed on an "AS IS" BASIS,
+  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  See the License for the specific language governing permissions and
+  limitations under the License.
+
+*/
+
+pragma solidity ^0.4.24;
+pragma experimental ABIEncoderV2;
+
+import "../../protocol/AssetProxy/ERC20Proxy.sol";
+import "../../protocol/AssetProxy/ERC721Proxy.sol";
+
+contract TestAssetDataDecoders is
+    ERC721Proxy
+{
+    /// @dev Decodes ERC721 Asset data.
+    /// @param assetData Encoded byte array.
+    /// @return proxyId Intended ERC721 proxy id.
+    /// @return token ERC721 token address.
+    /// @return tokenId ERC721 token id.
+    /// @return receiverData Additional data with no specific format, which
+    ///                      is passed to the receiving contract's onERC721Received.
+    function publicDecodeERC721Data(bytes memory assetData)
+        public
+        pure
+        returns (
+            address token,
+            uint256 tokenId,
+            bytes memory receiverData
+        )
+    {
+        (
+            token,
+            tokenId,
+            receiverData
+        ) = decodeERC721AssetData(assetData);
+
+        return (
+            token,
+            tokenId,
+            receiverData
+        );
+    }
+}
diff --git a/packages/contracts/src/contracts/current/test/TestAssetProxyDispatcher/TestAssetProxyDispatcher.sol b/packages/contracts/src/contracts/current/test/TestAssetProxyDispatcher/TestAssetProxyDispatcher.sol
index 11ca0617d..d469a07f0 100644
--- a/packages/contracts/src/contracts/current/test/TestAssetProxyDispatcher/TestAssetProxyDispatcher.sol
+++ b/packages/contracts/src/contracts/current/test/TestAssetProxyDispatcher/TestAssetProxyDispatcher.sol
@@ -23,12 +23,13 @@ import "../../protocol/Exchange/MixinAssetProxyDispatcher.sol";
 
 contract TestAssetProxyDispatcher is MixinAssetProxyDispatcher {
     function publicDispatchTransferFrom(
-        bytes memory assetMetadata,
+        bytes memory assetData,
+        uint8 assetProxyId,
         address from,
         address to,
         uint256 amount)
         public
     {
-        dispatchTransferFrom(assetMetadata, from, to, amount);
+        dispatchTransferFrom(assetData, assetProxyId, from, to, amount);
     }
 }
diff --git a/packages/contracts/src/contracts/current/test/TestLibBytes/TestLibBytes.sol b/packages/contracts/src/contracts/current/test/TestLibBytes/TestLibBytes.sol
index 69554605d..6f1898acd 100644
--- a/packages/contracts/src/contracts/current/test/TestLibBytes/TestLibBytes.sol
+++ b/packages/contracts/src/contracts/current/test/TestLibBytes/TestLibBytes.sol
@@ -28,24 +28,24 @@ contract TestLibBytes is
     /// @dev Pops the last byte off of a byte array by modifying its length.
     /// @param b Byte array that will be modified.
     /// @return The byte that was popped off.
-    function publicPopByte(bytes memory b)
+    function publicPopLastByte(bytes memory b)
         public
         pure
         returns (bytes memory, bytes1 result)
     {
-        result = popByte(b);
+        result = popLastByte(b);
         return (b, result);
     }
 
     /// @dev Pops the last 20 bytes off of a byte array by modifying its length.
     /// @param b Byte array that will be modified.
     /// @return The 20 byte address that was popped off.
-    function publicPopAddress(bytes memory b)
+    function publicPopLast20Bytes(bytes memory b)
         public
         pure
         returns (bytes memory, address result)
     {
-        result = popAddress(b);
+        result = popLast20Bytes(b);
         return (b, result);
     }
 
@@ -62,13 +62,29 @@ contract TestLibBytes is
         return equal;
     }
 
+    /// @dev Performs a deep copy of a byte array onto another byte array of greater than or equal length.
+    /// @param dest Byte array that will be overwritten with source bytes.
+    /// @param source Byte array to copy onto dest bytes.
+    function publicDeepCopyBytes(
+        bytes memory dest,
+        bytes memory source
+    )
+        public
+        pure
+        returns (bytes memory)
+    {
+        deepCopyBytes(dest, source);
+        return dest;
+    }
+
     /// @dev Reads an address from a position in a byte array.
     /// @param b Byte array containing an address.
     /// @param index Index in byte array of address.
     /// @return address from byte array.
     function publicReadAddress(
         bytes memory b,
-        uint256 index)
+        uint256 index
+    )
         public
         pure
         returns (address result)
@@ -84,7 +100,8 @@ contract TestLibBytes is
     function publicWriteAddress(
         bytes memory b,
         uint256 index,
-        address input)
+        address input
+    )
         public
         pure
         returns (bytes memory)
@@ -99,7 +116,8 @@ contract TestLibBytes is
     /// @return bytes32 value from byte array.
     function publicReadBytes32(
         bytes memory b,
-        uint256 index)
+        uint256 index
+    )
         public
         pure
         returns (bytes32 result)
@@ -115,7 +133,8 @@ contract TestLibBytes is
     function publicWriteBytes32(
         bytes memory b,
         uint256 index,
-        bytes32 input)
+        bytes32 input
+    )
         public
         pure
         returns (bytes memory)
@@ -130,7 +149,8 @@ contract TestLibBytes is
     /// @return uint256 value from byte array.
     function publicReadUint256(
         bytes memory b,
-        uint256 index)
+        uint256 index
+    )
         public
         pure
         returns (uint256 result)
@@ -146,7 +166,8 @@ contract TestLibBytes is
     function publicWriteUint256(
         bytes memory b,
         uint256 index,
-        uint256 input)
+        uint256 input
+    )
         public
         pure
         returns (bytes memory)
@@ -166,4 +187,38 @@ contract TestLibBytes is
         result = readFirst4(b);
         return result;
     }
+
+    /// @dev Reads nested bytes from a specific position.
+    /// @param b Byte array containing nested bytes.
+    /// @param index Index of nested bytes.
+    /// @return result Nested bytes.
+    function publicReadBytes(
+        bytes memory b,
+        uint256 index
+    )
+        public
+        pure
+        returns (bytes memory result)
+    {
+        result = readBytes(b, index);
+        return result;
+    }
+
+    /// @dev Inserts bytes at a specific position in a byte array.
+    /// @param b Byte array to insert <input> into.
+    /// @param index Index in byte array of <input>.
+    /// @param input bytes to insert.
+    /// @return b Updated input byte array
+    function publicWriteBytes(
+        bytes memory b,
+        uint256 index,
+        bytes memory input
+    )
+        public
+        pure
+        returns (bytes memory)
+    {
+        writeBytes(b, index, input);
+        return b;
+    }
 }
diff --git a/packages/contracts/src/contracts/current/test/TestLibMem/TestLibMem.sol b/packages/contracts/src/contracts/current/test/TestLibMem/TestLibMem.sol
new file mode 100644
index 000000000..b7e2e06b8
--- /dev/null
+++ b/packages/contracts/src/contracts/current/test/TestLibMem/TestLibMem.sol
@@ -0,0 +1,56 @@
+/*
+
+  Copyright 2018 ZeroEx Intl.
+
+  Licensed under the Apache License, Version 2.0 (the "License");
+  you may not use this file except in compliance with the License.
+  You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+  Unless required by applicable law or agreed to in writing, software
+  distributed under the License is distributed on an "AS IS" BASIS,
+  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  See the License for the specific language governing permissions and
+  limitations under the License.
+
+*/
+
+pragma solidity ^0.4.24;
+
+import "../../utils/LibMem/LibMem.sol";
+
+contract TestLibMem is
+    LibMem
+{
+
+    /// @dev Copies a block of memory from one location to another.
+    /// @param mem Memory contents we want to apply memCopy to
+    /// @param dest Destination offset into <mem>.
+    /// @param source Source offset into <mem>.
+    /// @param length Length of bytes to copy from <source> to <dest>
+    /// @return mem Memory contents after calling memCopy.
+    function testMemcpy(
+        bytes mem,
+        uint256 dest,
+        uint256 source,
+        uint256 length
+    )
+        public // not external, we need input in memory
+        pure
+        returns (bytes)
+    {
+        // Sanity check. Overflows are not checked.
+        require(source + length <= mem.length);
+        require(dest + length <= mem.length);
+
+        // Get pointer to memory contents
+        uint256 offset = getMemAddress(mem) + 32;
+
+        // Execute memCopy adjusted for memory array location
+        memCopy(offset + dest, offset + source, length);
+
+        // Return modified memory contents
+        return mem;
+    }
+}
diff --git a/packages/contracts/src/contracts/current/utils/LibBytes/LibBytes.sol b/packages/contracts/src/contracts/current/utils/LibBytes/LibBytes.sol
index df2221c93..10d7ce41a 100644
--- a/packages/contracts/src/contracts/current/utils/LibBytes/LibBytes.sol
+++ b/packages/contracts/src/contracts/current/utils/LibBytes/LibBytes.sol
@@ -18,31 +18,36 @@
 
 pragma solidity ^0.4.24;
 
-contract LibBytes {
+import "../LibMem/LibMem.sol";
+
+contract LibBytes is
+    LibMem
+{
 
     // Revert reasons
-    string constant GT_ZERO_LENGTH_REQUIRED = "Length must be greater than 0.";
-    string constant GTE_4_LENGTH_REQUIRED = "Length must be greater than or equal to 4.";
-    string constant GTE_20_LENGTH_REQUIRED = "Length must be greater than or equal to 20.";
-    string constant GTE_32_LENGTH_REQUIRED = "Length must be greater than or equal to 32.";
-    string constant INDEX_OUT_OF_BOUNDS = "Specified array index is out of bounds.";
+    string constant GREATER_THAN_ZERO_LENGTH_REQUIRED = "GREATER_THAN_ZERO_LENGTH_REQUIRED";
+    string constant GREATER_OR_EQUAL_TO_4_LENGTH_REQUIRED = "GREATER_OR_EQUAL_TO_4_LENGTH_REQUIRED";
+    string constant GREATER_OR_EQUAL_TO_20_LENGTH_REQUIRED = "GREATER_OR_EQUAL_TO_20_LENGTH_REQUIRED";
+    string constant GREATER_OR_EQUAL_TO_32_LENGTH_REQUIRED = "GREATER_OR_EQUAL_TO_32_LENGTH_REQUIRED";
+    string constant GREATER_OR_EQUAL_TO_NESTED_BYTES_LENGTH_REQUIRED = "GREATER_OR_EQUAL_TO_NESTED_BYTES_LENGTH_REQUIRED";
+    string constant GREATER_OR_EQUAL_TO_SOURCE_BYTES_LENGTH_REQUIRED = "GREATER_OR_EQUAL_TO_SOURCE_BYTES_LENGTH_REQUIRED";
 
     /// @dev Pops the last byte off of a byte array by modifying its length.
     /// @param b Byte array that will be modified.
     /// @return The byte that was popped off.
-    function popByte(bytes memory b)
+    function popLastByte(bytes memory b)
         internal
         pure
         returns (bytes1 result)
     {
         require(
             b.length > 0,
-            GT_ZERO_LENGTH_REQUIRED
+            GREATER_THAN_ZERO_LENGTH_REQUIRED
         );
 
         // Store last byte.
         result = b[b.length - 1];
-        
+
         assembly {
             // Decrement length of byte array.
             let newLen := sub(mload(b), 1)
@@ -54,14 +59,14 @@ contract LibBytes {
     /// @dev Pops the last 20 bytes off of a byte array by modifying its length.
     /// @param b Byte array that will be modified.
     /// @return The 20 byte address that was popped off.
-    function popAddress(bytes memory b)
+    function popLast20Bytes(bytes memory b)
         internal
         pure
         returns (address result)
     {
         require(
             b.length >= 20,
-            GTE_20_LENGTH_REQUIRED
+            GREATER_OR_EQUAL_TO_20_LENGTH_REQUIRED
         );
 
         // Store last 20 bytes.
@@ -75,41 +80,6 @@ contract LibBytes {
         return result;
     }
 
-    /// @dev Tests equality of two byte arrays.
-    /// @param lhs First byte array to compare.
-    /// @param rhs Second byte array to compare.
-    /// @return True if arrays are the same. False otherwise.
-    function areBytesEqual(
-        bytes memory lhs,
-        bytes memory rhs
-    )
-        internal
-        pure
-        returns (bool equal)
-    {
-        assembly {
-            // Get the number of words occupied by <lhs>
-            let lenFullWords := div(add(mload(lhs), 0x1F), 0x20)
-
-            // Add 1 to the number of words, to account for the length field
-            lenFullWords := add(lenFullWords, 0x1)
-
-            // Test equality word-by-word.
-            // Terminates early if there is a mismatch.
-            for {let i := 0} lt(i, lenFullWords) {i := add(i, 1)} {
-                let lhsWord := mload(add(lhs, mul(i, 0x20)))
-                let rhsWord := mload(add(rhs, mul(i, 0x20)))
-                equal := eq(lhsWord, rhsWord)
-                if eq(equal, 0) {
-                    // Break
-                    i := lenFullWords
-                }
-            }
-       }
-
-       return equal;
-    }
-
     /// @dev Reads an address from a position in a byte array.
     /// @param b Byte array containing an address.
     /// @param index Index in byte array of address.
@@ -124,8 +94,8 @@ contract LibBytes {
     {
         require(
             b.length >= index + 20,  // 20 is length of address
-            GTE_20_LENGTH_REQUIRED
-        ); 
+            GREATER_OR_EQUAL_TO_20_LENGTH_REQUIRED
+        );
 
         // Add offset to index:
         // 1. Arrays are prefixed by 32-byte length parameter (add 32 to index)
@@ -156,8 +126,8 @@ contract LibBytes {
     {
         require(
             b.length >= index + 20,  // 20 is length of address
-            GTE_20_LENGTH_REQUIRED
-        ); 
+            GREATER_OR_EQUAL_TO_20_LENGTH_REQUIRED
+        );
 
         // Add offset to index:
         // 1. Arrays are prefixed by 32-byte length parameter (add 32 to index)
@@ -195,7 +165,7 @@ contract LibBytes {
     {
         require(
             b.length >= index + 32,
-            GTE_32_LENGTH_REQUIRED
+            GREATER_OR_EQUAL_TO_32_LENGTH_REQUIRED
         );
 
         // Arrays are prefixed by a 256 bit length parameter
@@ -222,7 +192,7 @@ contract LibBytes {
     {
         require(
             b.length >= index + 32,
-            GTE_32_LENGTH_REQUIRED
+            GREATER_OR_EQUAL_TO_32_LENGTH_REQUIRED
         );
 
         // Arrays are prefixed by a 256 bit length parameter
@@ -274,11 +244,130 @@ contract LibBytes {
     {
         require(
             b.length >= 4,
-            GTE_4_LENGTH_REQUIRED
+            GREATER_OR_EQUAL_TO_4_LENGTH_REQUIRED
         );
         assembly {
             result := mload(add(b, 32))
         }
         return result;
     }
+
+    /// @dev Reads nested bytes from a specific position.
+    /// @param b Byte array containing nested bytes.
+    /// @param index Index of nested bytes.
+    /// @return result Nested bytes.
+    function readBytes(
+        bytes memory b,
+        uint256 index
+    )
+        internal
+        pure
+        returns (bytes memory result)
+    {
+        // Read length of nested bytes
+        uint256 nestedBytesLength = readUint256(b, index);
+        index += 32;
+
+        // Assert length of <b> is valid, given
+        // length of nested bytes
+        require(
+            b.length >= index + nestedBytesLength,
+            GREATER_OR_EQUAL_TO_NESTED_BYTES_LENGTH_REQUIRED
+        );
+
+        // Allocate memory and copy value to result
+        result = new bytes(nestedBytesLength);
+        memCopy(
+            getMemAddress(result) + 32, // +32 skips array length
+            getMemAddress(b) + index + 32,
+            nestedBytesLength
+        );
+
+        return result;
+    }
+
+    /// @dev Inserts bytes at a specific position in a byte array.
+    /// @param b Byte array to insert <input> into.
+    /// @param index Index in byte array of <input>.
+    /// @param input bytes to insert.
+    function writeBytes(
+        bytes memory b,
+        uint256 index,
+        bytes memory input
+    )
+        internal
+        pure
+    {
+        // Assert length of <b> is valid, given
+        // length of input
+        require(
+            b.length >= index + 32 /* 32 bytes to store length */ + input.length,
+            GREATER_OR_EQUAL_TO_NESTED_BYTES_LENGTH_REQUIRED
+        );
+
+        // Copy <input> into <b>
+        memCopy(
+            getMemAddress(b) + 32 + index,  // +32 to skip length of <b>
+            getMemAddress(input),           // includes length of <input>
+            input.length + 32               // +32 bytes to store <input> length
+        );
+    }
+
+    /// @dev Tests equality of two byte arrays.
+    /// @param lhs First byte array to compare.
+    /// @param rhs Second byte array to compare.
+    /// @return True if arrays are the same. False otherwise.
+    function areBytesEqual(
+        bytes memory lhs,
+        bytes memory rhs
+    )
+        internal
+        pure
+        returns (bool equal)
+    {
+        assembly {
+            // Get the number of words occupied by <lhs>
+            let lenFullWords := div(add(mload(lhs), 0x1F), 0x20)
+
+            // Add 1 to the number of words, to account for the length field
+            lenFullWords := add(lenFullWords, 0x1)
+
+            // Test equality word-by-word.
+            // Terminates early if there is a mismatch.
+            for {let i := 0} lt(i, lenFullWords) {i := add(i, 1)} {
+                let lhsWord := mload(add(lhs, mul(i, 0x20)))
+                let rhsWord := mload(add(rhs, mul(i, 0x20)))
+                equal := eq(lhsWord, rhsWord)
+                if eq(equal, 0) {
+                    // Break
+                    i := lenFullWords
+                }
+            }
+       }
+
+       return equal;
+    }
+
+    /// @dev Performs a deep copy of a byte array onto another byte array of greater than or equal length.
+    /// @param dest Byte array that will be overwritten with source bytes.
+    /// @param source Byte array to copy onto dest bytes.
+    function deepCopyBytes(
+        bytes memory dest,
+        bytes memory source
+    )
+        internal
+        pure
+    {
+        uint256 sourceLen = source.length;
+        // Dest length must be >= source length, or some bytes would not be copied.
+        require(
+            dest.length >= sourceLen,
+            GREATER_OR_EQUAL_TO_SOURCE_BYTES_LENGTH_REQUIRED
+        );
+        memCopy(
+            getMemAddress(dest) + 32,    // +32 to skip length of <dest>
+            getMemAddress(source) + 32,  // +32 to skip length of <source>
+            sourceLen
+        );
+    }
 }
diff --git a/packages/contracts/src/contracts/current/utils/LibMem/LibMem.sol b/packages/contracts/src/contracts/current/utils/LibMem/LibMem.sol
new file mode 100644
index 000000000..6afb9973a
--- /dev/null
+++ b/packages/contracts/src/contracts/current/utils/LibMem/LibMem.sol
@@ -0,0 +1,140 @@
+/*
+
+  Copyright 2018 ZeroEx Intl.
+
+  Licensed under the Apache License, Version 2.0 (the "License");
+  you may not use this file except in compliance with the License.
+  You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+  Unless required by applicable law or agreed to in writing, software
+  distributed under the License is distributed on an "AS IS" BASIS,
+  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  See the License for the specific language governing permissions and
+  limitations under the License.
+
+*/
+
+pragma solidity ^0.4.24;
+
+contract LibMem
+{
+
+    /// @dev Gets the memory address for a byte array.
+    /// @param input Byte array to lookup.
+    /// @return memoryAddress Memory address of byte array.
+    function getMemAddress(bytes memory input)
+        internal
+        pure
+        returns (uint256 memoryAddress)
+    {
+        assembly {
+            memoryAddress := input
+        }
+        return memoryAddress;
+    }
+
+    /// @dev Copies `length` bytes from memory location `source` to `dest`.
+    /// @param dest memory address to copy bytes to.
+    /// @param source memory address to copy bytes from.
+    /// @param length number of bytes to copy.
+    function memCopy(
+        uint256 dest,
+        uint256 source,
+        uint256 length
+    )
+        internal
+        pure
+    {
+        if (length < 32) {
+            // Handle a partial word by reading destination and masking
+            // off the bits we are interested in.
+            // This correctly handles overlap, zero lengths and source == dest
+            assembly {
+                let mask := sub(exp(256, sub(32, length)), 1)
+                let s := and(mload(source), not(mask))
+                let d := and(mload(dest), mask)
+                mstore(dest, or(s, d))
+            }
+        } else {
+            // Skip the O(length) loop when source == dest.
+            if (source == dest) {
+                return;
+            }
+
+            // For large copies we copy whole words at a time. The final
+            // word is aligned to the end of the range (instead of after the
+            // previous) to handle partial words. So a copy will look like this:
+            //
+            //  ####
+            //      ####
+            //          ####
+            //            ####
+            //
+            // We handle overlap in the source and destination range by
+            // changing the copying direction. This prevents us from
+            // overwriting parts of source that we still need to copy.
+            //
+            // This correctly handles source == dest
+            //
+            if (source > dest) {
+                assembly {
+                    // Record the total number of full words to copy
+                    let nWords := div(length, 32)
+
+                    // We subtract 32 from `sEnd` and `dEnd` because it
+                    // is easier to compare with in the loop, and these
+                    // are also the addresses we need for copying the
+                    // last bytes.
+                    length := sub(length, 32)
+                    let sEnd := add(source, length)
+                    let dEnd := add(dest, length)
+
+                    // Remember the last 32 bytes of source
+                    // This needs to be done here and not after the loop
+                    // because we may have overwritten the last bytes in
+                    // source already due to overlap.
+                    let last := mload(sEnd)
+
+                    // Copy whole words front to back
+                    for {let i := 0} lt(i, nWords) {i := add(i, 1)} {
+                        mstore(dest, mload(source))
+                        source := add(source, 32)
+                        dest := add(dest, 32)
+                    }
+
+                    // Write the last 32 bytes
+                    mstore(dEnd, last)
+                }
+            } else {
+                assembly {
+                    // Record the total number of full words to copy
+                    let nWords := div(length, 32)
+
+                    // We subtract 32 from `sEnd` and `dEnd` because those
+                    // are the starting points when copying a word at the end.
+                    length := sub(length, 32)
+                    let sEnd := add(source, length)
+                    let dEnd := add(dest, length)
+
+                    // Remember the first 32 bytes of source
+                    // This needs to be done here and not after the loop
+                    // because we may have overwritten the first bytes in
+                    // source already due to overlap.
+                    let first := mload(source)
+
+                    // Copy whole words back to front
+                    for {let i := 0} lt(i, nWords) {i := add(i, 1)} {
+                        mstore(dEnd, mload(sEnd))
+                        sEnd := sub(sEnd, 32)
+                        dEnd := sub(dEnd, 32)
+                    }
+
+                    // Write the first 32 bytes
+                    mstore(dest, first)
+                }
+            }
+        }
+    }
+}
diff --git a/packages/contracts/src/utils/artifacts.ts b/packages/contracts/src/utils/artifacts.ts
index 357c66a0a..bf7221d6d 100644
--- a/packages/contracts/src/utils/artifacts.ts
+++ b/packages/contracts/src/utils/artifacts.ts
@@ -2,6 +2,7 @@ import { ContractArtifact } from '@0xproject/sol-compiler';
 
 import * as AssetProxyOwner from '../artifacts/AssetProxyOwner.json';
 import * as DummyERC20Token from '../artifacts/DummyERC20Token.json';
+import * as DummyERC721Receiver from '../artifacts/DummyERC721Receiver.json';
 import * as DummyERC721Token from '../artifacts/DummyERC721Token.json';
 import * as ERC20Proxy from '../artifacts/ERC20Proxy.json';
 import * as ERC721Proxy from '../artifacts/ERC721Proxy.json';
@@ -9,8 +10,10 @@ import * as Exchange from '../artifacts/Exchange.json';
 import * as MixinAuthorizable from '../artifacts/MixinAuthorizable.json';
 import * as MultiSigWallet from '../artifacts/MultiSigWallet.json';
 import * as MultiSigWalletWithTimeLock from '../artifacts/MultiSigWalletWithTimeLock.json';
+import * as TestAssetDataDecoders from '../artifacts/TestAssetDataDecoders.json';
 import * as TestAssetProxyDispatcher from '../artifacts/TestAssetProxyDispatcher.json';
 import * as TestLibBytes from '../artifacts/TestLibBytes.json';
+import * as TestLibMem from '../artifacts/TestLibMem.json';
 import * as TestLibs from '../artifacts/TestLibs.json';
 import * as TestSignatureValidator from '../artifacts/TestSignatureValidator.json';
 import * as TokenRegistry from '../artifacts/TokenRegistry.json';
@@ -21,6 +24,7 @@ import * as ZRX from '../artifacts/ZRXToken.json';
 export const artifacts = {
     AssetProxyOwner: (AssetProxyOwner as any) as ContractArtifact,
     DummyERC20Token: (DummyERC20Token as any) as ContractArtifact,
+    DummyERC721Receiver: (DummyERC721Receiver as any) as ContractArtifact,
     DummyERC721Token: (DummyERC721Token as any) as ContractArtifact,
     ERC20Proxy: (ERC20Proxy as any) as ContractArtifact,
     ERC721Proxy: (ERC721Proxy as any) as ContractArtifact,
@@ -30,7 +34,9 @@ export const artifacts = {
     MultiSigWallet: (MultiSigWallet as any) as ContractArtifact,
     MultiSigWalletWithTimeLock: (MultiSigWalletWithTimeLock as any) as ContractArtifact,
     TestAssetProxyDispatcher: (TestAssetProxyDispatcher as any) as ContractArtifact,
+    TestAssetDataDecoders: (TestAssetDataDecoders as any) as ContractArtifact,
     TestLibBytes: (TestLibBytes as any) as ContractArtifact,
+    TestLibMem: (TestLibMem as any) as ContractArtifact,
     TestLibs: (TestLibs as any) as ContractArtifact,
     TestSignatureValidator: (TestSignatureValidator as any) as ContractArtifact,
     TokenRegistry: (TokenRegistry as any) as ContractArtifact,
diff --git a/packages/contracts/src/utils/assertions.ts b/packages/contracts/src/utils/assertions.ts
new file mode 100644
index 000000000..615e648f3
--- /dev/null
+++ b/packages/contracts/src/utils/assertions.ts
@@ -0,0 +1,63 @@
+import * as chai from 'chai';
+import * as _ from 'lodash';
+
+import { constants } from './constants';
+
+const expect = chai.expect;
+
+function _expectEitherErrorAsync<T>(p: Promise<T>, error1: string, error2: string): PromiseLike<void> {
+    return expect(p)
+        .to.be.rejected()
+        .then(e => {
+            expect(e).to.satisfy(
+                (err: Error) => _.includes(err.message, error1) || _.includes(err.message, error2),
+                `expected promise to reject with error message that includes "${error1}" or "${error2}", but got: ` +
+                    `"${e.message}"\n`,
+            );
+        });
+}
+
+/**
+ * Rejects if the given Promise does not reject with an error indicating
+ * insufficient funds.
+ * @param p the Promise which is expected to reject
+ * @returns a new Promise which will reject if the conditions are not met and
+ * otherwise resolve with no value.
+ */
+export function expectInsufficientFundsAsync<T>(p: Promise<T>): PromiseLike<void> {
+    return _expectEitherErrorAsync(p, 'insufficient funds', "sender doesn't have enough funds");
+}
+
+/**
+ * Rejects if the given Promise does not reject with a "revert" error or the
+ * given otherError.
+ * @param p the Promise which is expected to reject
+ * @param otherError the other error which is accepted as a valid reject error.
+ * @returns a new Promise which will reject if the conditions are not met and
+ * otherwise resolve with no value.
+ */
+export function expectRevertOrOtherErrorAsync<T>(p: Promise<T>, otherError: string): PromiseLike<void> {
+    return _expectEitherErrorAsync(p, constants.REVERT, otherError);
+}
+
+/**
+ * Rejects if the given Promise does not reject with a "revert" or "always
+ * failing transaction" error.
+ * @param p the Promise which is expected to reject
+ * @returns a new Promise which will reject if the conditions are not met and
+ * otherwise resolve with no value.
+ */
+export function expectRevertOrAlwaysFailingTransactionAsync<T>(p: Promise<T>): PromiseLike<void> {
+    return expectRevertOrOtherErrorAsync(p, 'always failing transaction');
+}
+
+/**
+ * Rejects if the given Promise does not reject with a "revert" or "Contract
+ * call failed" error.
+ * @param p the Promise which is expected to reject
+ * @returns a new Promise which will reject if the conditions are not met and
+ * otherwise resolve with no value.
+ */
+export function expectRevertOrContractCallFailedAsync<T>(p: Promise<T>): PromiseLike<void> {
+    return expectRevertOrOtherErrorAsync<T>(p, 'Contract call failed');
+}
diff --git a/packages/contracts/src/utils/constants.ts b/packages/contracts/src/utils/constants.ts
index 9b0b92545..ec3c8fd36 100644
--- a/packages/contracts/src/utils/constants.ts
+++ b/packages/contracts/src/utils/constants.ts
@@ -19,8 +19,19 @@ const TESTRPC_PRIVATE_KEYS_STRINGS = [
 export const constants = {
     INVALID_OPCODE: 'invalid opcode',
     REVERT: 'revert',
+    LIB_BYTES_GREATER_THAN_ZERO_LENGTH_REQUIRED: 'GREATER_THAN_ZERO_LENGTH_REQUIRED',
+    LIB_BYTES_GREATER_OR_EQUAL_TO_4_LENGTH_REQUIRED: 'GREATER_OR_EQUAL_TO_4_LENGTH_REQUIRED',
+    LIB_BYTES_GREATER_OR_EQUAL_TO_20_LENGTH_REQUIRED: 'GREATER_OR_EQUAL_TO_20_LENGTH_REQUIRED',
+    LIB_BYTES_GREATER_OR_EQUAL_TO_32_LENGTH_REQUIRED: 'GREATER_OR_EQUAL_TO_32_LENGTH_REQUIRED',
+    LIB_BYTES_GREATER_OR_EQUAL_TO_NESTED_BYTES_LENGTH_REQUIRED: 'GREATER_OR_EQUAL_TO_NESTED_BYTES_LENGTH_REQUIRED',
+    LIB_BYTES_GREATER_OR_EQUAL_TO_SOURCE_BYTES_LENGTH_REQUIRED: 'GREATER_OR_EQUAL_TO_SOURCE_BYTES_LENGTH_REQUIRED',
+    ERC20_INSUFFICIENT_BALANCE: 'Insufficient balance to complete transfer.',
+    ERC20_INSUFFICIENT_ALLOWANCE: 'Insufficient allowance to complete transfer.',
     TESTRPC_NETWORK_ID: 50,
-    AWAIT_TRANSACTION_MINED_MS: 100,
+    // Note(albrow): In practice V8 and most other engines limit the minimum
+    // interval for setInterval to 10ms. We still set it to 0 here in order to
+    // ensure we always use the minimum interval.
+    AWAIT_TRANSACTION_MINED_MS: 0,
     MAX_ETHERTOKEN_WITHDRAW_GAS: 43000,
     MAX_TOKEN_TRANSFERFROM_GAS: 80000,
     MAX_TOKEN_APPROVE_GAS: 60000,
diff --git a/packages/contracts/src/utils/coverage.ts b/packages/contracts/src/utils/coverage.ts
index a37939464..de29a3ecc 100644
--- a/packages/contracts/src/utils/coverage.ts
+++ b/packages/contracts/src/utils/coverage.ts
@@ -1,6 +1,5 @@
 import { devConstants } from '@0xproject/dev-utils';
 import { CoverageSubprovider, SolCompilerArtifactAdapter } from '@0xproject/sol-cov';
-import * as fs from 'fs';
 import * as _ from 'lodash';
 
 let coverageSubprovider: CoverageSubprovider;
@@ -15,7 +14,8 @@ export const coverage = {
     _getCoverageSubprovider(): CoverageSubprovider {
         const defaultFromAddress = devConstants.TESTRPC_FIRST_ADDRESS;
         const solCompilerArtifactAdapter = new SolCompilerArtifactAdapter();
-        const subprovider = new CoverageSubprovider(solCompilerArtifactAdapter, defaultFromAddress);
+        const isVerbose = true;
+        const subprovider = new CoverageSubprovider(solCompilerArtifactAdapter, defaultFromAddress, isVerbose);
         return subprovider;
     },
 };
diff --git a/packages/contracts/src/utils/erc20_wrapper.ts b/packages/contracts/src/utils/erc20_wrapper.ts
index dceeceeea..91c9d50b7 100644
--- a/packages/contracts/src/utils/erc20_wrapper.ts
+++ b/packages/contracts/src/utils/erc20_wrapper.ts
@@ -3,8 +3,8 @@ import { Web3Wrapper } from '@0xproject/web3-wrapper';
 import { Provider } from 'ethereum-types';
 import * as _ from 'lodash';
 
-import { DummyERC20TokenContract } from '../contract_wrappers/generated/dummy_e_r_c20_token';
-import { ERC20ProxyContract } from '../contract_wrappers/generated/e_r_c20_proxy';
+import { DummyERC20TokenContract } from '../generated_contract_wrappers/dummy_e_r_c20_token';
+import { ERC20ProxyContract } from '../generated_contract_wrappers/e_r_c20_proxy';
 
 import { artifacts } from './artifacts';
 import { constants } from './constants';
diff --git a/packages/contracts/src/utils/erc721_wrapper.ts b/packages/contracts/src/utils/erc721_wrapper.ts
index 13fdf630e..b20d9acd2 100644
--- a/packages/contracts/src/utils/erc721_wrapper.ts
+++ b/packages/contracts/src/utils/erc721_wrapper.ts
@@ -4,8 +4,8 @@ import { Web3Wrapper } from '@0xproject/web3-wrapper';
 import { Provider } from 'ethereum-types';
 import * as _ from 'lodash';
 
-import { DummyERC721TokenContract } from '../contract_wrappers/generated/dummy_e_r_c721_token';
-import { ERC721ProxyContract } from '../contract_wrappers/generated/e_r_c721_proxy';
+import { DummyERC721TokenContract } from '../generated_contract_wrappers/dummy_e_r_c721_token';
+import { ERC721ProxyContract } from '../generated_contract_wrappers/e_r_c721_proxy';
 
 import { artifacts } from './artifacts';
 import { constants } from './constants';
diff --git a/packages/contracts/src/utils/exchange_wrapper.ts b/packages/contracts/src/utils/exchange_wrapper.ts
index dd278e77c..4cc8f0b89 100644
--- a/packages/contracts/src/utils/exchange_wrapper.ts
+++ b/packages/contracts/src/utils/exchange_wrapper.ts
@@ -1,10 +1,10 @@
 import { AssetProxyId, SignedOrder } from '@0xproject/types';
 import { BigNumber } from '@0xproject/utils';
 import { Web3Wrapper } from '@0xproject/web3-wrapper';
-import { LogEntry, Provider, TransactionReceiptWithDecodedLogs } from 'ethereum-types';
+import { Provider, TransactionReceiptWithDecodedLogs } from 'ethereum-types';
 import * as _ from 'lodash';
 
-import { ExchangeContract } from '../contract_wrappers/generated/exchange';
+import { ExchangeContract } from '../generated_contract_wrappers/exchange';
 
 import { constants } from './constants';
 import { formatters } from './formatters';
@@ -60,14 +60,14 @@ export class ExchangeWrapper {
     public async fillOrderNoThrowAsync(
         signedOrder: SignedOrder,
         from: string,
-        opts: { takerAssetFillAmount?: BigNumber } = {},
+        opts: { takerAssetFillAmount?: BigNumber; gas?: number } = {},
     ): Promise<TransactionReceiptWithDecodedLogs> {
         const params = orderUtils.createFill(signedOrder, opts.takerAssetFillAmount);
         const txHash = await this._exchange.fillOrderNoThrow.sendTransactionAsync(
             params.order,
             params.takerAssetFillAmount,
             params.signature,
-            { from },
+            { from, gas: opts.gas },
         );
         const tx = await this._logDecoder.getTxWithDecodedLogsAsync(txHash);
         return tx;
@@ -105,14 +105,14 @@ export class ExchangeWrapper {
     public async batchFillOrdersNoThrowAsync(
         orders: SignedOrder[],
         from: string,
-        opts: { takerAssetFillAmounts?: BigNumber[] } = {},
+        opts: { takerAssetFillAmounts?: BigNumber[]; gas?: number } = {},
     ): Promise<TransactionReceiptWithDecodedLogs> {
         const params = formatters.createBatchFill(orders, opts.takerAssetFillAmounts);
         const txHash = await this._exchange.batchFillOrdersNoThrow.sendTransactionAsync(
             params.orders,
             params.takerAssetFillAmounts,
             params.signatures,
-            { from },
+            { from, gas: opts.gas },
         );
         const tx = await this._logDecoder.getTxWithDecodedLogsAsync(txHash);
         return tx;
@@ -135,14 +135,14 @@ export class ExchangeWrapper {
     public async marketSellOrdersNoThrowAsync(
         orders: SignedOrder[],
         from: string,
-        opts: { takerAssetFillAmount: BigNumber },
+        opts: { takerAssetFillAmount: BigNumber; gas?: number },
     ): Promise<TransactionReceiptWithDecodedLogs> {
         const params = formatters.createMarketSellOrders(orders, opts.takerAssetFillAmount);
         const txHash = await this._exchange.marketSellOrdersNoThrow.sendTransactionAsync(
             params.orders,
             params.takerAssetFillAmount,
             params.signatures,
-            { from },
+            { from, gas: opts.gas },
         );
         const tx = await this._logDecoder.getTxWithDecodedLogsAsync(txHash);
         return tx;
@@ -165,14 +165,14 @@ export class ExchangeWrapper {
     public async marketBuyOrdersNoThrowAsync(
         orders: SignedOrder[],
         from: string,
-        opts: { makerAssetFillAmount: BigNumber },
+        opts: { makerAssetFillAmount: BigNumber; gas?: number },
     ): Promise<TransactionReceiptWithDecodedLogs> {
         const params = formatters.createMarketBuyOrders(orders, opts.makerAssetFillAmount);
         const txHash = await this._exchange.marketBuyOrdersNoThrow.sendTransactionAsync(
             params.orders,
             params.makerAssetFillAmount,
             params.signatures,
-            { from },
+            { from, gas: opts.gas },
         );
         const tx = await this._logDecoder.getTxWithDecodedLogsAsync(txHash);
         return tx;
diff --git a/packages/contracts/src/utils/formatters.ts b/packages/contracts/src/utils/formatters.ts
index 1035f2d7c..32e4787d6 100644
--- a/packages/contracts/src/utils/formatters.ts
+++ b/packages/contracts/src/utils/formatters.ts
@@ -2,6 +2,7 @@ import { SignedOrder } from '@0xproject/types';
 import { BigNumber } from '@0xproject/utils';
 import * as _ from 'lodash';
 
+import { constants } from './constants';
 import { orderUtils } from './order_utils';
 import { BatchCancelOrders, BatchFillOrders, MarketBuyOrders, MarketSellOrders } from './types';
 
@@ -28,8 +29,11 @@ export const formatters = {
             signatures: [],
             takerAssetFillAmount,
         };
-        _.forEach(signedOrders, signedOrder => {
+        _.forEach(signedOrders, (signedOrder, i) => {
             const orderWithoutExchangeAddress = orderUtils.getOrderWithoutExchangeAddress(signedOrder);
+            if (i !== 0) {
+                orderWithoutExchangeAddress.takerAssetData = constants.NULL_BYTES;
+            }
             marketSellOrders.orders.push(orderWithoutExchangeAddress);
             marketSellOrders.signatures.push(signedOrder.signature);
         });
@@ -41,8 +45,11 @@ export const formatters = {
             signatures: [],
             makerAssetFillAmount,
         };
-        _.forEach(signedOrders, signedOrder => {
+        _.forEach(signedOrders, (signedOrder, i) => {
             const orderWithoutExchangeAddress = orderUtils.getOrderWithoutExchangeAddress(signedOrder);
+            if (i !== 0) {
+                orderWithoutExchangeAddress.makerAssetData = constants.NULL_BYTES;
+            }
             marketBuyOrders.orders.push(orderWithoutExchangeAddress);
             marketBuyOrders.signatures.push(signedOrder.signature);
         });
diff --git a/packages/contracts/src/utils/increase_time.ts b/packages/contracts/src/utils/increase_time.ts
new file mode 100644
index 000000000..4565d8dbc
--- /dev/null
+++ b/packages/contracts/src/utils/increase_time.ts
@@ -0,0 +1,31 @@
+import * as _ from 'lodash';
+
+import { constants } from './constants';
+import { web3Wrapper } from './web3_wrapper';
+
+let firstAccount: string | undefined;
+
+/**
+ * Increases time by the given number of seconds and then mines a block so that
+ * the current block timestamp has the offset applied.
+ * @param seconds the number of seconds by which to incrase the time offset.
+ * @returns a new Promise which will resolve with the new total time offset or
+ * reject if the time could not be increased.
+ */
+export async function increaseTimeAndMineBlockAsync(seconds: number): Promise<number> {
+    if (_.isUndefined(firstAccount)) {
+        const accounts = await web3Wrapper.getAvailableAddressesAsync();
+        firstAccount = accounts[0];
+    }
+
+    const offset = await web3Wrapper.increaseTimeAsync(seconds);
+    // Note: we need to send a transaction after increasing time so
+    // that a block is actually mined. The contract looks at the
+    // last mined block for the timestamp.
+    await web3Wrapper.awaitTransactionSuccessAsync(
+        await web3Wrapper.sendTransactionAsync({ from: firstAccount, to: firstAccount, value: 0 }),
+        constants.AWAIT_TRANSACTION_MINED_MS,
+    );
+
+    return offset;
+}
diff --git a/packages/contracts/src/utils/log_decoder.ts b/packages/contracts/src/utils/log_decoder.ts
index 07d10e69d..07127ba79 100644
--- a/packages/contracts/src/utils/log_decoder.ts
+++ b/packages/contracts/src/utils/log_decoder.ts
@@ -39,6 +39,7 @@ export class LogDecoder {
     }
     public decodeLogOrThrow<ArgsType extends DecodedLogArgs>(log: LogEntry): LogWithDecodedArgs<ArgsType> | RawLog {
         const logWithDecodedArgsOrLog = this._abiDecoder.tryToDecodeLogOrNoop(log);
+        // tslint:disable-next-line:no-unnecessary-type-assertion
         if (_.isUndefined((logWithDecodedArgsOrLog as LogWithDecodedArgs<ArgsType>).args)) {
             throw new Error(`Unable to decode log: ${JSON.stringify(log)}`);
         }
diff --git a/packages/contracts/src/utils/match_order_tester.ts b/packages/contracts/src/utils/match_order_tester.ts
index 6170188bc..fbb1b99db 100644
--- a/packages/contracts/src/utils/match_order_tester.ts
+++ b/packages/contracts/src/utils/match_order_tester.ts
@@ -1,38 +1,21 @@
-import { BlockchainLifecycle } from '@0xproject/dev-utils';
-import { assetProxyUtils, crypto, orderHashUtils } from '@0xproject/order-utils';
+import { assetProxyUtils, orderHashUtils } from '@0xproject/order-utils';
 import { AssetProxyId, SignedOrder } from '@0xproject/types';
 import { BigNumber } from '@0xproject/utils';
 import * as chai from 'chai';
-import { LogWithDecodedArgs } from 'ethereum-types';
-import ethUtil = require('ethereumjs-util');
 import * as _ from 'lodash';
 
-import { DummyERC20TokenContract } from '../contract_wrappers/generated/dummy_e_r_c20_token';
-import { DummyERC721TokenContract } from '../contract_wrappers/generated/dummy_e_r_c721_token';
-import { ERC20ProxyContract } from '../contract_wrappers/generated/e_r_c20_proxy';
-import { ERC721ProxyContract } from '../contract_wrappers/generated/e_r_c721_proxy';
-import {
-    CancelContractEventArgs,
-    ExchangeContract,
-    FillContractEventArgs,
-} from '../contract_wrappers/generated/exchange';
 import { chaiSetup } from '../utils/chai_setup';
-import { constants } from '../utils/constants';
 import { ERC20Wrapper } from '../utils/erc20_wrapper';
 import { ERC721Wrapper } from '../utils/erc721_wrapper';
 import { ExchangeWrapper } from '../utils/exchange_wrapper';
-import { OrderFactory } from '../utils/order_factory';
 import {
-    ContractName,
     ERC20BalancesByOwner,
     ERC721TokenIdsByOwner,
     TransferAmountsByMatchOrders as TransferAmounts,
 } from '../utils/types';
-import { provider, web3Wrapper } from '../utils/web3_wrapper';
 
 chaiSetup.configure();
 const expect = chai.expect;
-const blockchainLifecycle = new BlockchainLifecycle(web3Wrapper);
 
 export class MatchOrderTester {
     private _exchangeWrapper: ExchangeWrapper;
@@ -112,11 +95,6 @@ export class MatchOrderTester {
         initialTakerAssetFilledAmountLeft?: BigNumber,
         initialTakerAssetFilledAmountRight?: BigNumber,
     ): Promise<[ERC20BalancesByOwner, ERC721TokenIdsByOwner]> {
-        // Test setup & verify preconditions
-        const makerAddressLeft = signedOrderLeft.makerAddress;
-        const makerAddressRight = signedOrderRight.makerAddress;
-        const feeRecipientAddressLeft = signedOrderLeft.feeRecipientAddress;
-        const feeRecipientAddressRight = signedOrderRight.feeRecipientAddress;
         // Verify Left order preconditions
         const orderTakerAssetFilledAmountLeft = await this._exchangeWrapper.getTakerAssetFilledAmountAsync(
             orderHashUtils.getOrderHashHex(signedOrderLeft),
@@ -259,11 +237,11 @@ export class MatchOrderTester {
         const expectedNewERC20BalancesByOwner = _.cloneDeep(erc20BalancesByOwner);
         const expectedNewERC721TokenIdsByOwner = _.cloneDeep(erc721TokenIdsByOwner);
         // Left Maker Asset (Right Taker Asset)
-        const makerAssetProxyIdLeft = assetProxyUtils.decodeProxyDataId(signedOrderLeft.makerAssetData);
+        const makerAssetProxyIdLeft = assetProxyUtils.decodeAssetDataId(signedOrderLeft.makerAssetData);
         if (makerAssetProxyIdLeft === AssetProxyId.ERC20) {
             // Decode asset data
-            const erc20ProxyData = assetProxyUtils.decodeERC20ProxyData(signedOrderLeft.makerAssetData);
-            const makerAssetAddressLeft = erc20ProxyData.tokenAddress;
+            const erc20AssetData = assetProxyUtils.decodeERC20AssetData(signedOrderLeft.makerAssetData);
+            const makerAssetAddressLeft = erc20AssetData.tokenAddress;
             const takerAssetAddressRight = makerAssetAddressLeft;
             // Left Maker
             expectedNewERC20BalancesByOwner[makerAddressLeft][makerAssetAddressLeft] = expectedNewERC20BalancesByOwner[
@@ -281,9 +259,9 @@ export class MatchOrderTester {
             ][makerAssetAddressLeft].add(expectedTransferAmounts.amountReceivedByTaker);
         } else if (makerAssetProxyIdLeft === AssetProxyId.ERC721) {
             // Decode asset data
-            const erc721ProxyData = assetProxyUtils.decodeERC721ProxyData(signedOrderLeft.makerAssetData);
-            const makerAssetAddressLeft = erc721ProxyData.tokenAddress;
-            const makerAssetIdLeft = erc721ProxyData.tokenId;
+            const erc721AssetData = assetProxyUtils.decodeERC721AssetData(signedOrderLeft.makerAssetData);
+            const makerAssetAddressLeft = erc721AssetData.tokenAddress;
+            const makerAssetIdLeft = erc721AssetData.tokenId;
             const takerAssetAddressRight = makerAssetAddressLeft;
             const takerAssetIdRight = makerAssetIdLeft;
             // Left Maker
@@ -294,11 +272,11 @@ export class MatchOrderTester {
         }
         // Left Taker Asset (Right Maker Asset)
         // Note: This exchange is only between the order makers: the Taker does not receive any of the left taker asset.
-        const takerAssetProxyIdLeft = assetProxyUtils.decodeProxyDataId(signedOrderLeft.takerAssetData);
+        const takerAssetProxyIdLeft = assetProxyUtils.decodeAssetDataId(signedOrderLeft.takerAssetData);
         if (takerAssetProxyIdLeft === AssetProxyId.ERC20) {
             // Decode asset data
-            const erc20ProxyData = assetProxyUtils.decodeERC20ProxyData(signedOrderLeft.takerAssetData);
-            const takerAssetAddressLeft = erc20ProxyData.tokenAddress;
+            const erc20AssetData = assetProxyUtils.decodeERC20AssetData(signedOrderLeft.takerAssetData);
+            const takerAssetAddressLeft = erc20AssetData.tokenAddress;
             const makerAssetAddressRight = takerAssetAddressLeft;
             // Left Maker
             expectedNewERC20BalancesByOwner[makerAddressLeft][takerAssetAddressLeft] = expectedNewERC20BalancesByOwner[
@@ -312,9 +290,9 @@ export class MatchOrderTester {
             );
         } else if (takerAssetProxyIdLeft === AssetProxyId.ERC721) {
             // Decode asset data
-            const erc721ProxyData = assetProxyUtils.decodeERC721ProxyData(signedOrderRight.makerAssetData);
-            const makerAssetAddressRight = erc721ProxyData.tokenAddress;
-            const makerAssetIdRight = erc721ProxyData.tokenId;
+            const erc721AssetData = assetProxyUtils.decodeERC721AssetData(signedOrderRight.makerAssetData);
+            const makerAssetAddressRight = erc721AssetData.tokenAddress;
+            const makerAssetIdRight = erc721AssetData.tokenId;
             const takerAssetAddressLeft = makerAssetAddressRight;
             const takerAssetIdLeft = makerAssetIdRight;
             // Right Maker
diff --git a/packages/contracts/src/utils/multi_sig_wrapper.ts b/packages/contracts/src/utils/multi_sig_wrapper.ts
index 9971e8f6e..f0098bd5e 100644
--- a/packages/contracts/src/utils/multi_sig_wrapper.ts
+++ b/packages/contracts/src/utils/multi_sig_wrapper.ts
@@ -3,10 +3,9 @@ import { Web3Wrapper } from '@0xproject/web3-wrapper';
 import { Provider, TransactionReceiptWithDecodedLogs } from 'ethereum-types';
 import * as _ from 'lodash';
 
-import { AssetProxyOwnerContract } from '../contract_wrappers/generated/asset_proxy_owner';
-import { MultiSigWalletContract } from '../contract_wrappers/generated/multi_sig_wallet';
+import { AssetProxyOwnerContract } from '../generated_contract_wrappers/asset_proxy_owner';
+import { MultiSigWalletContract } from '../generated_contract_wrappers/multi_sig_wallet';
 
-import { constants } from './constants';
 import { LogDecoder } from './log_decoder';
 
 export class MultiSigWrapper {
@@ -45,6 +44,7 @@ export class MultiSigWrapper {
         txId: BigNumber,
         from: string,
     ): Promise<TransactionReceiptWithDecodedLogs> {
+        // tslint:disable-next-line:no-unnecessary-type-assertion
         const txHash = await (this
             ._multiSig as AssetProxyOwnerContract).executeRemoveAuthorizedAddress.sendTransactionAsync(txId, { from });
         const tx = await this._logDecoder.getTxWithDecodedLogsAsync(txHash);
diff --git a/packages/contracts/src/utils/order_factory.ts b/packages/contracts/src/utils/order_factory.ts
index dd02e1f5c..009dbc396 100644
--- a/packages/contracts/src/utils/order_factory.ts
+++ b/packages/contracts/src/utils/order_factory.ts
@@ -1,7 +1,6 @@
 import { generatePseudoRandomSalt, orderHashUtils } from '@0xproject/order-utils';
 import { Order, SignatureType, SignedOrder } from '@0xproject/types';
 import { BigNumber } from '@0xproject/utils';
-import * as _ from 'lodash';
 
 import { constants } from './constants';
 import { signingUtils } from './signing_utils';
diff --git a/packages/contracts/src/utils/order_utils.ts b/packages/contracts/src/utils/order_utils.ts
index 180761f2c..a9f994d80 100644
--- a/packages/contracts/src/utils/order_utils.ts
+++ b/packages/contracts/src/utils/order_utils.ts
@@ -1,7 +1,7 @@
 import { OrderWithoutExchangeAddress, SignedOrder } from '@0xproject/types';
 import { BigNumber } from '@0xproject/utils';
-import ethUtil = require('ethereumjs-util');
 
+import { constants } from './constants';
 import { CancelOrder, MatchOrder } from './types';
 
 export const orderUtils = {
@@ -44,6 +44,8 @@ export const orderUtils = {
             leftSignature: signedOrderLeft.signature,
             rightSignature: signedOrderRight.signature,
         };
+        fill.right.makerAssetData = constants.NULL_BYTES;
+        fill.right.takerAssetData = constants.NULL_BYTES;
         return fill;
     },
 };
diff --git a/packages/contracts/src/utils/profiler.ts b/packages/contracts/src/utils/profiler.ts
new file mode 100644
index 000000000..85ee24f22
--- /dev/null
+++ b/packages/contracts/src/utils/profiler.ts
@@ -0,0 +1,27 @@
+import { devConstants } from '@0xproject/dev-utils';
+import { ProfilerSubprovider, SolCompilerArtifactAdapter } from '@0xproject/sol-cov';
+import * as _ from 'lodash';
+
+let profilerSubprovider: ProfilerSubprovider;
+
+export const profiler = {
+    start(): void {
+        profiler.getProfilerSubproviderSingleton().start();
+    },
+    stop(): void {
+        profiler.getProfilerSubproviderSingleton().stop();
+    },
+    getProfilerSubproviderSingleton(): ProfilerSubprovider {
+        if (_.isUndefined(profilerSubprovider)) {
+            profilerSubprovider = profiler._getProfilerSubprovider();
+        }
+        return profilerSubprovider;
+    },
+    _getProfilerSubprovider(): ProfilerSubprovider {
+        const defaultFromAddress = devConstants.TESTRPC_FIRST_ADDRESS;
+        const solCompilerArtifactAdapter = new SolCompilerArtifactAdapter();
+        const isVerbose = true;
+        const subprovider = new ProfilerSubprovider(solCompilerArtifactAdapter, defaultFromAddress, isVerbose);
+        return subprovider;
+    },
+};
diff --git a/packages/contracts/src/utils/revert_trace.ts b/packages/contracts/src/utils/revert_trace.ts
new file mode 100644
index 000000000..0bf8384bc
--- /dev/null
+++ b/packages/contracts/src/utils/revert_trace.ts
@@ -0,0 +1,21 @@
+import { devConstants } from '@0xproject/dev-utils';
+import { RevertTraceSubprovider, SolCompilerArtifactAdapter } from '@0xproject/sol-cov';
+import * as _ from 'lodash';
+
+let revertTraceSubprovider: RevertTraceSubprovider;
+
+export const revertTrace = {
+    getRevertTraceSubproviderSingleton(): RevertTraceSubprovider {
+        if (_.isUndefined(revertTraceSubprovider)) {
+            revertTraceSubprovider = revertTrace._getRevertTraceSubprovider();
+        }
+        return revertTraceSubprovider;
+    },
+    _getRevertTraceSubprovider(): RevertTraceSubprovider {
+        const defaultFromAddress = devConstants.TESTRPC_FIRST_ADDRESS;
+        const solCompilerArtifactAdapter = new SolCompilerArtifactAdapter();
+        const isVerbose = true;
+        const subprovider = new RevertTraceSubprovider(solCompilerArtifactAdapter, defaultFromAddress, isVerbose);
+        return subprovider;
+    },
+};
diff --git a/packages/contracts/src/utils/token_registry_wrapper.ts b/packages/contracts/src/utils/token_registry_wrapper.ts
index 240c06fdc..91895aa59 100644
--- a/packages/contracts/src/utils/token_registry_wrapper.ts
+++ b/packages/contracts/src/utils/token_registry_wrapper.ts
@@ -1,7 +1,7 @@
 import { Web3Wrapper } from '@0xproject/web3-wrapper';
 import { Provider } from 'ethereum-types';
 
-import { TokenRegistryContract } from '../contract_wrappers/generated/token_registry';
+import { TokenRegistryContract } from '../generated_contract_wrappers/token_registry';
 
 import { Token } from './types';
 
diff --git a/packages/contracts/src/utils/types.ts b/packages/contracts/src/utils/types.ts
index 360e1fdbc..bb8c12088 100644
--- a/packages/contracts/src/utils/types.ts
+++ b/packages/contracts/src/utils/types.ts
@@ -1,6 +1,6 @@
-import { Order, OrderWithoutExchangeAddress } from '@0xproject/types';
+import { OrderWithoutExchangeAddress } from '@0xproject/types';
 import { BigNumber } from '@0xproject/utils';
-import { AbiDefinition, ContractAbi } from 'ethereum-types';
+import { AbiDefinition } from 'ethereum-types';
 
 export interface ERC20BalancesByOwner {
     [ownerAddress: string]: {
@@ -90,11 +90,14 @@ export enum ContractName {
     AccountLevels = 'AccountLevels',
     EtherDelta = 'EtherDelta',
     Arbitrage = 'Arbitrage',
+    TestAssetDataDecoders = 'TestAssetDataDecoders',
     TestAssetProxyDispatcher = 'TestAssetProxyDispatcher',
+    TestLibMem = 'TestLibMem',
     TestLibs = 'TestLibs',
     TestSignatureValidator = 'TestSignatureValidator',
     ERC20Proxy = 'ERC20Proxy',
     ERC721Proxy = 'ERC721Proxy',
+    DummyERC721Receiver = 'DummyERC721Receiver',
     DummyERC721Token = 'DummyERC721Token',
     TestLibBytes = 'TestLibBytes',
     Authorizable = 'Authorizable',
diff --git a/packages/contracts/src/utils/web3_wrapper.ts b/packages/contracts/src/utils/web3_wrapper.ts
index 1049ab967..c9d83a02d 100644
--- a/packages/contracts/src/utils/web3_wrapper.ts
+++ b/packages/contracts/src/utils/web3_wrapper.ts
@@ -1,19 +1,82 @@
 import { devConstants, env, EnvVars, web3Factory } from '@0xproject/dev-utils';
 import { prependSubprovider } from '@0xproject/subproviders';
+import { logUtils } from '@0xproject/utils';
 import { Web3Wrapper } from '@0xproject/web3-wrapper';
-import { Provider } from 'ethereum-types';
+import * as _ from 'lodash';
 
 import { coverage } from './coverage';
+import { profiler } from './profiler';
+import { revertTrace } from './revert_trace';
 
-export const txDefaults = {
+enum ProviderType {
+    Ganache = 'ganache',
+    Geth = 'geth',
+}
+
+let testProvider: ProviderType;
+switch (process.env.TEST_PROVIDER) {
+    case undefined:
+        testProvider = ProviderType.Ganache;
+        break;
+    case 'ganache':
+        testProvider = ProviderType.Ganache;
+        break;
+    case 'geth':
+        testProvider = ProviderType.Geth;
+        break;
+    default:
+        throw new Error(`Unknown TEST_PROVIDER: ${process.env.TEST_PROVIDER}`);
+}
+
+const ganacheTxDefaults = {
     from: devConstants.TESTRPC_FIRST_ADDRESS,
     gas: devConstants.GAS_LIMIT,
 };
-const providerConfigs = { shouldUseInProcessGanache: true };
+const gethTxDefaults = {
+    from: devConstants.TESTRPC_FIRST_ADDRESS,
+};
+export const txDefaults = testProvider === ProviderType.Ganache ? ganacheTxDefaults : gethTxDefaults;
+
+const gethConfigs = {
+    shouldUseInProcessGanache: false,
+    rpcUrl: 'http://localhost:8501',
+    shouldUseFakeGasEstimate: false,
+};
+const ganacheConfigs = {
+    shouldUseInProcessGanache: true,
+};
+const providerConfigs = testProvider === ProviderType.Ganache ? ganacheConfigs : gethConfigs;
+
 export const provider = web3Factory.getRpcProvider(providerConfigs);
 const isCoverageEnabled = env.parseBoolean(EnvVars.SolidityCoverage);
+const isProfilerEnabled = env.parseBoolean(EnvVars.SolidityProfiler);
+const isRevertTraceEnabled = env.parseBoolean(EnvVars.SolidityRevertTrace);
+const enabledSubproviderCount = _.filter([isCoverageEnabled, isProfilerEnabled, isRevertTraceEnabled], _.identity)
+    .length;
+if (enabledSubproviderCount > 1) {
+    throw new Error(`Only one of coverage, profiler, or revert trace subproviders can be enabled at a time`);
+}
 if (isCoverageEnabled) {
     const coverageSubprovider = coverage.getCoverageSubproviderSingleton();
     prependSubprovider(provider, coverageSubprovider);
 }
+if (isProfilerEnabled) {
+    if (testProvider === ProviderType.Ganache) {
+        logUtils.warn(
+            "Gas costs in Ganache traces are incorrect and we don't recommend using it for profiling. Please switch to Geth",
+        );
+        process.exit(1);
+    }
+    const profilerSubprovider = profiler.getProfilerSubproviderSingleton();
+    logUtils.log(
+        "By default profilerSubprovider is stopped so that you don't get noise from setup code. Don't forget to start it before the code you want to profile and stop it afterwards",
+    );
+    profilerSubprovider.stop();
+    prependSubprovider(provider, profilerSubprovider);
+}
+if (isRevertTraceEnabled) {
+    const revertTraceSubprovider = revertTrace.getRevertTraceSubproviderSingleton();
+    prependSubprovider(provider, revertTraceSubprovider);
+}
+
 export const web3Wrapper = new Web3Wrapper(provider);