JS: Added class OrderBook for listening to order books.

src/js/orderbook.js

@@ -0,0 +1,104 @@
+// Routines for working with an orderbook.
+//
+// Events:
+
+// var network = require("./network.js");
+
+var EventEmitter = require('events').EventEmitter;
+var Amount = require('./amount').Amount;
+var UInt160 = require('./uint160').UInt160;
+var Currency = require('./currency').Currency;
+
+var extend = require('extend');
+
+var OrderBook = function (remote,
+                          currency_out, issuer_out,
+                          currency_in,  issuer_in) {
+  var self = this;
+
+  this._remote = remote;
+  this._currency_out = currency_out;
+  this._issuer_out = issuer_out;
+  this._currency_in = currency_in;
+  this._issuer_in = issuer_in;
+
+  this._subs = 0;
+
+  // Ledger entry object
+  // Important: This must never be overwritten, only extend()-ed
+  this._entry = {};
+
+  this.on('newListener', function (type, listener) {
+    if (OrderBook.subscribe_events.indexOf(type) !== -1) {
+      if (!self._subs && 'open' === self._remote._online_state) {
+        self._remote.request_subscribe()
+          .books([self.to_json()])
+          .request();
+      }
+      self._subs  += 1;
+    }
+  });
+
+  this.on('removeListener', function (type, listener) {
+    if (OrderBook.subscribe_events.indexOf(type) !== -1) {
+      self._subs  -= 1;
+
+      if (!self._subs && 'open' === self._remote._online_state) {
+        self._remote.request_unsubscribe()
+          .books([self.to_json()])
+          .request();
+      }
+    }
+  });
+
+  this._remote.on('connect', function () {
+    if (self._subs) {
+      self._remote.request_subscribe()
+        .books([self.to_json()])
+        .request();
+    }
+  });
+
+  return this;
+};
+
+OrderBook.prototype = new EventEmitter;
+
+/**
+ * List of events that require a remote subscription to the orderbook.
+ */
+OrderBook.subscribe_events = ['transaction'];
+
+OrderBook.prototype.to_json = function ()
+{
+  var json = {
+    "CurrencyOut": this._currency_out,
+    "CurrencyIn": this._currency_in
+  };
+
+  if (json["CurrencyOut"] !== "XRP") json["IssuerOut"] = this._issuer_out;
+  if (json["CurrencyIn"] !== "XRP")  json["IssuerIn"]  = this._issuer_in;
+
+  return json;
+};
+
+/**
+ * Whether the OrderBook is valid.
+ *
+ * Note: This only checks whether the parameters (currencies and issuer) are
+ *       syntactically valid. It does not check anything against the ledger.
+ */
+OrderBook.prototype.is_valid = function ()
+{
+  return (
+    Currency.is_valid(this._currency_in) &&
+    (this._currency_in !== "XRP" && UInt160.is_valid(this._issuer_in)) &&
+    Currency.is_valid(this._currency_out) &&
+    (this._currency_out !== "XRP" && UInt160.is_valid(this._issuer_out)) &&
+    !(this._currency_in === "XRP" && this._currency_out === "XRP")
+  );
+};
+
+exports.OrderBook	    = OrderBook;
+
+// vim:sw=2:sts=2:ts=8:et

src/js/remote.js

@@ -22,6 +22,7 @@ var UInt160       = require('./amount').UInt160;
 var Transaction   = require('./transaction').Transaction;
 var Account       = require('./account').Account;
 var Meta          = require('./meta').Meta;
+var OrderBook     = require('./orderbook').OrderBook;
 
 var utils         = require('./utils');
 var config        = require('./config');
@@ -181,6 +182,31 @@ Request.prototype.rt_accounts = function (accounts) {
   return this.accounts(accounts, true);
 };
 
+Request.prototype.books = function (books) {
+  var procBooks = [];
+
+  for (var i = 0, l = books.length; i < l; i++) {
+    var book = books[i];
+
+    var json = {
+      "CurrencyOut": Currency.json_rewrite(book["CurrencyOut"]),
+      "CurrencyIn": Currency.json_rewrite(book["CurrencyIn"])
+    };
+
+    if (json["CurrencyOut"] !== "XRP") {
+      json["IssuerOut"] = UInt160.json_rewrite(book["IssuerOut"]);
+    }
+    if (json["CurrencyIn"] !== "XRP") {
+      json["IssuerIn"]  = UInt160.json_rewrite(book["IssuerIn"]);
+    }
+
+    procBooks.push(json);
+  }
+  this.message.books = procBooks;
+
+  return this;
+};
+
 //
 // Remote - access to a remote Ripple server via websocket.
 //
@@ -1036,6 +1062,15 @@ Remote.prototype.account = function (accountId) {
   return this._accounts[account.to_json()] = account;
 };
 
+Remote.prototype.book = function (currency_out, issuer_out,
+                                  currency_in,  issuer_in) {
+  var book = new OrderBook(this,
+                           currency_out, issuer_out,
+                           currency_in,  issuer_in);
+
+  return book;
+}
+
 // Return the next account sequence if possible.
 // <-- undefined or Sequence
 Remote.prototype.account_seq = function (account, advance) {