4 files changed, 30 insertions, 20 deletions
diff --git a/packages/0x.js/src/0x.ts b/packages/0x.js/src/0x.ts
index 0dd728ff1..7627f1d6e 100644
--- a/packages/0x.js/src/0x.ts
+++ b/packages/0x.js/src/0x.ts
@@ -15,7 +15,7 @@ import { OrderStateWatcher } from './order_watcher/order_state_watcher';
 import { zeroExConfigSchema } from './schemas/zero_ex_config_schema';
 import { zeroExPrivateNetworkConfigSchema } from './schemas/zero_ex_private_network_config_schema';
 import { zeroExPublicNetworkConfigSchema } from './schemas/zero_ex_public_network_config_schema';
-import { Web3Provider, ZeroExConfig, ZeroExError } from './types';
+import { OrderStateWatcherConfig, ZeroExConfig, ZeroExError } from './types';
 import { assert } from './utils/assert';
 import { constants } from './utils/constants';
 import { decorators } from './utils/decorators';
@@ -57,11 +57,6 @@ export class ZeroEx {
      * tokenTransferProxy smart contract.
      */
     public proxy: TokenTransferProxyWrapper;
-    /**
-     * An instance of the OrderStateWatcher class containing methods for watching a set of orders for relevant
-     * blockchain state changes.
-     */
-    public orderStateWatcher: OrderStateWatcher;
     private _web3Wrapper: Web3Wrapper;
     private _abiDecoder: AbiDecoder;
     /**
@@ -197,13 +192,6 @@ export class ZeroEx {
             config.tokenRegistryContractAddress,
         );
         this.etherToken = new EtherTokenWrapper(this._web3Wrapper, config.networkId, this._abiDecoder, this.token);
-        this.orderStateWatcher = new OrderStateWatcher(
-            this._web3Wrapper,
-            this._abiDecoder,
-            this.token,
-            this.exchange,
-            config.orderWatcherConfig,
-        );
     }
     /**
      * Sets a new web3 provider for 0x.js. Updating the provider will stop all
@@ -336,6 +324,21 @@ export class ZeroEx {
         const txReceipt = await txReceiptPromise;
         return txReceipt;
     }
+    /**
+     * Instantiates and returns a new OrderStateWatcher instance.
+     * Defaults to watching the pending state.
+     * @param   config      The configuration object. Look up the type for the description.
+     * @return  An instance of the 0x.js OrderStateWatcher class.
+     */
+    public createOrderStateWatcher(config?: OrderStateWatcherConfig) {
+        return new OrderStateWatcher(
+            this._web3Wrapper,
+            this._abiDecoder,
+            this.token,
+            this.exchange,
+            config,
+        );
+    }
     /*
      * HACK: `TokenWrapper` needs a token transfer proxy address. `TokenTransferProxy` address is fetched from
      * an `ExchangeWrapper`. `ExchangeWrapper` needs `TokenWrapper` to validate orders, creating a dependency cycle.
diff --git a/packages/0x.js/src/order_watcher/event_watcher.ts b/packages/0x.js/src/order_watcher/event_watcher.ts
index 246ab8292..d01542a8c 100644
--- a/packages/0x.js/src/order_watcher/event_watcher.ts
+++ b/packages/0x.js/src/order_watcher/event_watcher.ts
@@ -22,8 +22,10 @@ export class EventWatcher {
     private _pollingIntervalMs: number;
     private _intervalIdIfExists?: NodeJS.Timer;
     private _lastEvents: LogEntry[] = [];
-    constructor(web3Wrapper: Web3Wrapper, pollingIntervalIfExistsMs: undefined | number) {
+    private _stateLayer: BlockParamLiteral;
+    constructor(web3Wrapper: Web3Wrapper, pollingIntervalIfExistsMs: undefined | number, stateLayer: BlockParamLiteral = BlockParamLiteral.Latest) {
         this._web3Wrapper = web3Wrapper;
+        this._stateLayer = stateLayer;
         this._pollingIntervalMs = _.isUndefined(pollingIntervalIfExistsMs)
             ? DEFAULT_EVENT_POLLING_INTERVAL_MS
             : pollingIntervalIfExistsMs;
@@ -69,8 +71,8 @@ export class EventWatcher {
     }
     private async _getEventsAsync(): Promise<LogEntry[]> {
         const eventFilter = {
-            fromBlock: BlockParamLiteral.Pending,
-            toBlock: BlockParamLiteral.Pending,
+            fromBlock: this._stateLayer,
+            toBlock: this._stateLayer,
         };
         const events = await this._web3Wrapper.getLogsAsync(eventFilter);
         return events;
diff --git a/packages/0x.js/src/order_watcher/order_state_watcher.ts b/packages/0x.js/src/order_watcher/order_state_watcher.ts
index 9cccadb7f..bfd250e21 100644
--- a/packages/0x.js/src/order_watcher/order_state_watcher.ts
+++ b/packages/0x.js/src/order_watcher/order_state_watcher.ts
@@ -86,10 +86,13 @@ export class OrderStateWatcher {
         this._abiDecoder = abiDecoder;
         this._web3Wrapper = web3Wrapper;
         const pollingIntervalIfExistsMs = _.isUndefined(config) ? undefined : config.eventPollingIntervalMs;
-        this._eventWatcher = new EventWatcher(web3Wrapper, pollingIntervalIfExistsMs);
+        const stateLayer = _.isUndefined(config) || _.isUndefined(config.stateLayer)
+            ? BlockParamLiteral.Latest
+            : config.stateLayer;
+        this._eventWatcher = new EventWatcher(web3Wrapper, pollingIntervalIfExistsMs, stateLayer);
         this._balanceAndProxyAllowanceLazyStore = new BalanceAndProxyAllowanceLazyStore(
             token,
-            BlockParamLiteral.Pending,
+            stateLayer,
         );
         this._orderFilledCancelledLazyStore = new OrderFilledCancelledLazyStore(exchange);
         this._orderStateUtils = new OrderStateUtils(
diff --git a/packages/0x.js/src/types.ts b/packages/0x.js/src/types.ts
index 38cfb6306..7f1f140ca 100644
--- a/packages/0x.js/src/types.ts
+++ b/packages/0x.js/src/types.ts
@@ -165,16 +165,18 @@ export type Web3Provider = Web3.Provider;
 
 /*
  * orderExpirationCheckingIntervalMs: How often to check for expired orders. Default: 50
- * eventPollingIntervalMs: How often to poll the Ethereum node for new events. Defaults: 200
+ * eventPollingIntervalMs: How often to poll the Ethereum node for new events. Default: 200
  * expirationMarginMs: Amount of time before order expiry that you'd like to be notified
- * of an orders expiration. Defaults: 0
+ * of an orders expiration. Default: 0
  * cleanupJobIntervalMs: How often to run a cleanup job which revalidates all the orders. Defaults: 1h
+ * stateLayer: Optional blockchain state layer OrderWatcher will monitor for new events. Default: latest
  */
 export interface OrderStateWatcherConfig {
     orderExpirationCheckingIntervalMs?: number;
     eventPollingIntervalMs?: number;
     expirationMarginMs?: number;
     cleanupJobIntervalMs?: number;
+    stateLayer: BlockParamLiteral;
 }
 
 /*