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/*
This file is part of ethereum.js.
ethereum.js is free software: you can redistribute it and/or modify
it under the terms of the GNU Lesser General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
ethereum.js is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public License
along with ethereum.js. If not, see <http://www.gnu.org/licenses/>.
*/
/** @file httprpc.js
* @authors:
* Marek Kotewicz <marek@ethdev.com>
* Marian Oancea <marian@ethdev.com>
* @date 2014
*/
// TODO: is these line is supposed to be here?
if (process.env.NODE_ENV !== 'build') {
var XMLHttpRequest = require('xmlhttprequest').XMLHttpRequest; // jshint ignore:line
}
/**
* HttpRpcProvider object prototype is implementing 'provider protocol'
* Should be used when we want to connect to ethereum backend over http && jsonrpc
* It's compatible with cpp client
* The contructor allows to specify host uri
* This provider is using in-browser polling mechanism
*/
var HttpRpcProvider = function (host) {
this.handlers = [];
this.host = host;
};
/// Transforms inner message to proper jsonrpc object
/// @param inner message object
/// @returns jsonrpc object
function formatJsonRpcObject(object) {
return {
jsonrpc: '2.0',
method: object.call,
params: object.args,
id: object._id
};
}
/// Transforms jsonrpc object to inner message
/// @param incoming jsonrpc message
/// @returns inner message object
function formatJsonRpcMessage(message) {
var object = JSON.parse(message);
return {
_id: object.id,
data: object.result,
error: object.error
};
}
/// Prototype object method
/// Asynchronously sends request to server
/// @param payload is inner message object
/// @param cb is callback which is being called when response is comes back
HttpRpcProvider.prototype.sendRequest = function (payload, cb) {
var data = formatJsonRpcObject(payload);
var request = new XMLHttpRequest();
request.open("POST", this.host, true);
request.send(JSON.stringify(data));
request.onreadystatechange = function () {
if (request.readyState === 4 && cb) {
cb(request);
}
};
};
/// Prototype object method
/// Should be called when we want to send single api request to server
/// Asynchronous
/// On response it passes message to handlers
/// @param payload is inner message object
HttpRpcProvider.prototype.send = function (payload) {
var self = this;
this.sendRequest(payload, function (request) {
self.handlers.forEach(function (handler) {
handler.call(self, formatJsonRpcMessage(request.responseText));
});
});
};
/// Prototype object method
/// Should be called only for polling requests
/// Asynchronous
/// On response it passege message to handlers, but only if message's result is true or not empty array
/// Otherwise response is being silently ignored
/// @param payload is inner message object
/// @id is id of poll that we are calling
HttpRpcProvider.prototype.poll = function (payload, id) {
var self = this;
this.sendRequest(payload, function (request) {
var parsed = JSON.parse(request.responseText);
if (parsed.error || (parsed.result instanceof Array ? parsed.result.length === 0 : !parsed.result)) {
return;
}
self.handlers.forEach(function (handler) {
handler.call(self, {_event: payload.call, _id: id, data: parsed.result});
});
});
};
/// Prototype object property
/// Should be used to set message handlers for this provider
Object.defineProperty(HttpRpcProvider.prototype, "onmessage", {
set: function (handler) {
this.handlers.push(handler);
}
});
module.exports = HttpRpcProvider;
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