Add ability to specify own request id generator for a client, togethe…

…r with corresponding tests and README update

README.md

@@ -207,6 +207,7 @@ Every client supports these options:
 
 * `reviver` -> Function to use as a JSON reviver
 * `replacer` -> Function to use as a JSON replacer
+* `idGenerator` -> Function to generate request ids with. If omitted, Jayson will just generate a "random" number like this: `Math.round(Math.random() * Math.pow(2, 24))`
 
 ##### Client.http
 
@@ -320,7 +321,7 @@ server.http().listen(3001, '127.0.0.1', function() {
 
 Every request to `add` on the public server will now relay the request to the private server. See the client example in `examples/relay/client.js`.
 
-#### Events
+#### Server events
 
 In addition to events that are specific to a certain interface, all servers will emit the following events:
 

lib/client.js

@@ -20,7 +20,8 @@ var Client = function(server, options) {
 
   var defaults = {
     reviver: null,
-    replacer: null
+    replacer: null,
+    idGenerator: utils.generateId
   };
 
   this.options = utils.merge(defaults, options || {});
@@ -73,7 +74,9 @@ Client.prototype.request = function(method, params, id, callback) {
     var hasCallback = typeof(callback) === 'function';
 
     try {
-      var request = utils.request(method, params, id);
+      var request = utils.request(method, params, id, {
+        generator: this.options.idGenerator
+      });
     } catch(err) {
       if(hasCallback) return callback(err);
       throw err;

lib/utils.js

@@ -8,11 +8,12 @@ var Utils = module.exports;
  *  @param {String} method Name of method to call
  *  @param {Array|Object} params Array of parameters passed to the method as specified, or an object of parameter names and corresponding value
  *  @param {String|Number|null} [id] Request ID can be a string, number, null for explicit notification or left out for automatic generation
+ *  @param {Object} [options] Optional name => value pairs of settings
  *  @throws {TypeError} If any of the parameters are invalid
  *  @return {Object} A JSON-RPC 2.0 request
  *  @api public
  */
-Utils.request = function(method, params, id) {
+Utils.request = function(method, params, id, options) {
   if(typeof(method) !== 'string') {
     throw new TypeError(method + ' must be a string');
   }
@@ -21,6 +22,8 @@ Utils.request = function(method, params, id) {
     throw new TypeError(params + ' must be an object or an array');
   }
 
+  options = options || {};
+
   var request = {
     jsonrpc: "2.0",
     params: params,
@@ -29,7 +32,8 @@ Utils.request = function(method, params, id) {
 
   // if id was left out, generate one (null means explicit notification)
   if(typeof(id) === 'undefined') {
-    request.id = Utils.generateId();
+    var generator = typeof(options.generator) === 'function' ? options.generator : Utils.generateId;
+    request.id =  generator(request);
   } else {
     request.id = id;
   }
@@ -46,7 +50,7 @@ Utils.request = function(method, params, id) {
  *  @api public
  */
 Utils.response = function(error, result, id) {
-  id = id || null;
+  id = typeof(id) === 'undefined' || id === null ? null : id;
   var response = { jsonrpc: "2.0", id: id };
   // one or the other with precedence for errors
   if(error) response.error = error;
@@ -109,7 +113,7 @@ Utils.parseBody = function(req, reviver, callback) {
 /**
  *  Wraps a server instance around a HTTP request listener (used by the HTTP and HTTPS server modules)
  *  @param {JaysonServer} server Instance of JaysonServer (typically jayson.Server.http or jayson.Server.https)
- *  @param {Object} [options] Optional name => value pair of settings
+ *  @param {Object} [options] Optional name => value pairs of settings
  *  @return {Function}
  *  @api private
  */

test/client.test.js

@@ -40,7 +40,7 @@ describe('jayson client instance', function() {
 
   it('should support reviving and replacing', support.clientReviveReplace(client));
 
-  it('should return the response as received if given a two-param callback', function(done) {
+  it('should return the response as received if given a callback with arity 2', function(done) {
     var a = 11, b = 9;
     client.request('add', [a, b], function(err, response) {
       arguments.length.should.equal(2);
@@ -52,6 +52,20 @@ describe('jayson client instance', function() {
     });
   });
 
+  it('should support specifying a request id generator', function(done) {
+    var ordinal = 0, a = 9, b = 2;
+    client.options.idGenerator = function(request) { return ordinal++; };
+    client.request('add', [a, b], function(err, response) {
+      should.not.exist(err);
+      should.exist(response);
+      response.should.have.property('result', a + b);
+      response.should.have.property('id', 0);
+      ordinal.should.equal(1);
+      delete client.options.idGenerator;
+      done();
+    });
+  });
+
   it('should be able to execute a notification request', function(done) {
     var a = 3, b = 4;
     client.request('add', [a, b], null, function(err, response) {