| /* |
| * |
| * Copyright 2014, Google Inc. |
| * All rights reserved. |
| * |
| * Redistribution and use in source and binary forms, with or without |
| * modification, are permitted provided that the following conditions are |
| * met: |
| * |
| * * Redistributions of source code must retain the above copyright |
| * notice, this list of conditions and the following disclaimer. |
| * * Redistributions in binary form must reproduce the above |
| * copyright notice, this list of conditions and the following disclaimer |
| * in the documentation and/or other materials provided with the |
| * distribution. |
| * * Neither the name of Google Inc. nor the names of its |
| * contributors may be used to endorse or promote products derived from |
| * this software without specific prior written permission. |
| * |
| * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS |
| * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT |
| * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR |
| * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT |
| * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, |
| * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT |
| * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, |
| * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY |
| * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
| * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE |
| * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
| * |
| */ |
| |
| var _ = require('underscore'); |
| var ProtoBuf = require('protobufjs'); |
| var fs = require('fs'); |
| var util = require('util'); |
| |
| var Transform = require('stream').Transform; |
| |
| var builder = ProtoBuf.loadProtoFile(__dirname + '/math.proto'); |
| var math = builder.build('math'); |
| |
| var makeConstructor = require('../surface_server.js').makeServerConstructor; |
| |
| /** |
| * Get a function that deserializes a specific type of protobuf. |
| * @param {function()} cls The constructor of the message type to deserialize |
| * @return {function(Buffer):cls} The deserialization function |
| */ |
| function deserializeCls(cls) { |
| /** |
| * Deserialize a buffer to a message object |
| * @param {Buffer} arg_buf The buffer to deserialize |
| * @return {cls} The resulting object |
| */ |
| return function deserialize(arg_buf) { |
| return cls.decode(arg_buf); |
| }; |
| } |
| |
| /** |
| * Get a function that serializes objects to a buffer by protobuf class. |
| * @param {function()} Cls The constructor of the message type to serialize |
| * @return {function(Cls):Buffer} The serialization function |
| */ |
| function serializeCls(Cls) { |
| /** |
| * Serialize an object to a Buffer |
| * @param {Object} arg The object to serialize |
| * @return {Buffer} The serialized object |
| */ |
| return function serialize(arg) { |
| return new Buffer(new Cls(arg).encode().toBuffer()); |
| }; |
| } |
| |
| /* This function call creates a server constructor for servers that that expose |
| * the four specified methods. This specifies how to serialize messages that the |
| * server sends and deserialize messages that the client sends, and whether the |
| * client or the server will send a stream of messages, for each method. This |
| * also specifies a prefix that will be added to method names when sending them |
| * on the wire. This function call and all of the preceding code in this file |
| * are intended to approximate what the generated code will look like for the |
| * math service */ |
| var Server = makeConstructor({ |
| Div: { |
| serialize: serializeCls(math.DivReply), |
| deserialize: deserializeCls(math.DivArgs), |
| client_stream: false, |
| server_stream: false |
| }, |
| Fib: { |
| serialize: serializeCls(math.Num), |
| deserialize: deserializeCls(math.FibArgs), |
| client_stream: false, |
| server_stream: true |
| }, |
| Sum: { |
| serialize: serializeCls(math.Num), |
| deserialize: deserializeCls(math.Num), |
| client_stream: true, |
| server_stream: false |
| }, |
| DivMany: { |
| serialize: serializeCls(math.DivReply), |
| deserialize: deserializeCls(math.DivArgs), |
| client_stream: true, |
| server_stream: true |
| } |
| }, '/Math/'); |
| |
| /** |
| * Server function for division. Provides the /Math/DivMany and /Math/Div |
| * functions (Div is just DivMany with only one stream element). For each |
| * DivArgs parameter, responds with a DivReply with the results of the division |
| * @param {Object} call The object containing request and cancellation info |
| * @param {function(Error, *)} cb Response callback |
| */ |
| function mathDiv(call, cb) { |
| var req = call.request; |
| if (req.divisor == 0) { |
| cb(new Error('cannot divide by zero')); |
| } |
| cb(null, { |
| quotient: req.dividend / req.divisor, |
| remainder: req.dividend % req.divisor |
| }); |
| } |
| |
| /** |
| * Server function for Fibonacci numbers. Provides the /Math/Fib function. Reads |
| * a single parameter that indicates the number of responses, and then responds |
| * with a stream of that many Fibonacci numbers. |
| * @param {stream} stream The stream for sending responses. |
| */ |
| function mathFib(stream) { |
| // Here, call is a standard writable Node object Stream |
| var previous = 0, current = 1; |
| for (var i = 0; i < stream.request.limit; i++) { |
| stream.write({num: current}); |
| var temp = current; |
| current += previous; |
| previous = temp; |
| } |
| stream.end(); |
| } |
| |
| /** |
| * Server function for summation. Provides the /Math/Sum function. Reads a |
| * stream of number parameters, then responds with their sum. |
| * @param {stream} call The stream of arguments. |
| * @param {function(Error, *)} cb Response callback |
| */ |
| function mathSum(call, cb) { |
| // Here, call is a standard readable Node object Stream |
| var sum = 0; |
| call.on('data', function(data) { |
| sum += data.num | 0; |
| }); |
| call.on('end', function() { |
| cb(null, {num: sum}); |
| }); |
| } |
| |
| function mathDivMany(stream) { |
| // Here, call is a standard duplex Node object Stream |
| util.inherits(DivTransform, Transform); |
| function DivTransform() { |
| var options = {objectMode: true}; |
| Transform.call(this, options); |
| } |
| DivTransform.prototype._transform = function(div_args, encoding, callback) { |
| if (div_args.divisor == 0) { |
| callback(new Error('cannot divide by zero')); |
| } |
| callback(null, { |
| quotient: div_args.dividend / div_args.divisor, |
| remainder: div_args.dividend % div_args.divisor |
| }); |
| }; |
| var transform = new DivTransform(); |
| stream.pipe(transform); |
| transform.pipe(stream); |
| } |
| |
| var server = new Server({ |
| Div: mathDiv, |
| Fib: mathFib, |
| Sum: mathSum, |
| DivMany: mathDivMany |
| }); |
| |
| if (require.main === module) { |
| server.bind('localhost:7070').listen(); |
| } |
| |
| /** |
| * See docs for server |
| */ |
| module.exports = server; |