Initial checkin of gRPC to third_party/

third_party/grpc/src/node/src/client.js

Index: third_party/grpc/src/node/src/client.js
diff --git a/third_party/grpc/src/node/src/client.js b/third_party/grpc/src/node/src/client.js
new file mode 100644
index 0000000000000000000000000000000000000000..9cc5a62bdbcafe486222a0f081f37111078c81b0
--- /dev/null
+++ b/third_party/grpc/src/node/src/client.js
@@ -0,0 +1,776 @@
+/*
+ *
+ * Copyright 2015-2016, 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.
+ *
+ */
+
+/**
+ * Client module
+ *
+ * This module contains the factory method for creating Client classes, and the
+ * method calling code for all types of methods.
+ *
+ * For example, to create a client and call a method on it:
+ *
+ * var proto_obj = grpc.load(proto_file_path);
+ * var Client = proto_obj.package.subpackage.ServiceName;
+ * var client = new Client(server_address, client_credentials);
+ * var call = client.unaryMethod(arguments, callback);
+ *
+ * @module
+ */
+
+'use strict';
+
+var _ = require('lodash');
+
+var grpc = require('./grpc_extension');
+
+var common = require('./common');
+
+var Metadata = require('./metadata');
+
+var EventEmitter = require('events').EventEmitter;
+
+var stream = require('stream');
+
+var Readable = stream.Readable;
+var Writable = stream.Writable;
+var Duplex = stream.Duplex;
+var util = require('util');
+var version = require('../../../package.json').version;
+
+util.inherits(ClientWritableStream, Writable);
+
+/**
+ * A stream that the client can write to. Used for calls that are streaming from
+ * the client side.
+ * @constructor
+ * @param {grpc.Call} call The call object to send data with
+ * @param {function(*):Buffer=} serialize Serialization function for writes.
+ */
+function ClientWritableStream(call, serialize) {
+  Writable.call(this, {objectMode: true});
+  this.call = call;
+  this.serialize = common.wrapIgnoreNull(serialize);
+  this.on('finish', function() {
+    var batch = {};
+    batch[grpc.opType.SEND_CLOSE_FROM_CLIENT] = true;
+    call.startBatch(batch, function() {});
+  });
+}
+
+/**
+ * Attempt to write the given chunk. Calls the callback when done. This is an
+ * implementation of a method needed for implementing stream.Writable.
+ * @access private
+ * @param {Buffer} chunk The chunk to write
+ * @param {string} encoding Used to pass write flags
+ * @param {function(Error=)} callback Called when the write is complete
+ */
+function _write(chunk, encoding, callback) {
+  /* jshint validthis: true */
+  var batch = {};
+  var message = this.serialize(chunk);
+  if (_.isFinite(encoding)) {
+    /* Attach the encoding if it is a finite number. This is the closest we
+     * can get to checking that it is valid flags */
+    message.grpcWriteFlags = encoding;
+  }
+  batch[grpc.opType.SEND_MESSAGE] = message;
+  this.call.startBatch(batch, function(err, event) {
+    if (err) {
+      // Something has gone wrong. Stop writing by failing to call callback
+      return;
+    }
+    callback();
+  });
+}
+
+ClientWritableStream.prototype._write = _write;
+
+util.inherits(ClientReadableStream, Readable);
+
+/**
+ * A stream that the client can read from. Used for calls that are streaming
+ * from the server side.
+ * @constructor
+ * @param {grpc.Call} call The call object to read data with
+ * @param {function(Buffer):*=} deserialize Deserialization function for reads
+ */
+function ClientReadableStream(call, deserialize) {
+  Readable.call(this, {objectMode: true});
+  this.call = call;
+  this.finished = false;
+  this.reading = false;
+  this.deserialize = common.wrapIgnoreNull(deserialize);
+  /* Status generated from reading messages from the server. Overrides the
+   * status from the server if not OK */
+  this.read_status = null;
+  /* Status received from the server. */
+  this.received_status = null;
+}
+
+/**
+ * Called when all messages from the server have been processed. The status
+ * parameter indicates that the call should end with that status. status
+ * defaults to OK if not provided.
+ * @param {Object!} status The status that the call should end with
+ */
+function _readsDone(status) {
+  /* jshint validthis: true */
+  if (!status) {
+    status = {code: grpc.status.OK, details: 'OK'};
+  }
+  this.finished = true;
+  this.read_status = status;
+  this._emitStatusIfDone();
+}
+
+ClientReadableStream.prototype._readsDone = _readsDone;
+
+/**
+ * Called to indicate that we have received a status from the server.
+ */
+function _receiveStatus(status) {
+  /* jshint validthis: true */
+  this.received_status = status;
+  this._emitStatusIfDone();
+}
+
+ClientReadableStream.prototype._receiveStatus = _receiveStatus;
+
+/**
+ * If we have both processed all incoming messages and received the status from
+ * the server, emit the status. Otherwise, do nothing.
+ */
+function _emitStatusIfDone() {
+  /* jshint validthis: true */
+  var status;
+  if (this.read_status && this.received_status) {
+    if (this.read_status.code !== grpc.status.OK) {
+      status = this.read_status;
+    } else {
+      status = this.received_status;
+    }
+    this.emit('status', status);
+    if (status.code !== grpc.status.OK) {
+      var error = new Error(status.details);
+      error.code = status.code;
+      error.metadata = status.metadata;
+      this.emit('error', error);
+      return;
+    }
+  }
+}
+
+ClientReadableStream.prototype._emitStatusIfDone = _emitStatusIfDone;
+
+/**
+ * Read the next object from the stream.
+ * @access private
+ * @param {*} size Ignored because we use objectMode=true
+ */
+function _read(size) {
+  /* jshint validthis: true */
+  var self = this;
+  /**
+   * Callback to be called when a READ event is received. Pushes the data onto
+   * the read queue and starts reading again if applicable
+   * @param {grpc.Event} event READ event object
+   */
+  function readCallback(err, event) {
+    if (err) {
+      // Something has gone wrong. Stop reading and wait for status
+      self.finished = true;
+      self._readsDone();
+      return;
+    }
+    var data = event.read;
+    var deserialized;
+    try {
+      deserialized = self.deserialize(data);
+    } catch (e) {
+      self._readsDone({code: grpc.status.INTERNAL,
+                       details: 'Failed to parse server response'});
+    }
+    if (data === null) {
+      self._readsDone();
+    }
+    if (self.push(deserialized) && data !== null) {
+      var read_batch = {};
+      read_batch[grpc.opType.RECV_MESSAGE] = true;
+      self.call.startBatch(read_batch, readCallback);
+    } else {
+      self.reading = false;
+    }
+  }
+  if (self.finished) {
+    self.push(null);
+  } else {
+    if (!self.reading) {
+      self.reading = true;
+      var read_batch = {};
+      read_batch[grpc.opType.RECV_MESSAGE] = true;
+      self.call.startBatch(read_batch, readCallback);
+    }
+  }
+}
+
+ClientReadableStream.prototype._read = _read;
+
+util.inherits(ClientDuplexStream, Duplex);
+
+/**
+ * A stream that the client can read from or write to. Used for calls with
+ * duplex streaming.
+ * @constructor
+ * @param {grpc.Call} call Call object to proxy
+ * @param {function(*):Buffer=} serialize Serialization function for requests
+ * @param {function(Buffer):*=} deserialize Deserialization function for
+ *     responses
+ */
+function ClientDuplexStream(call, serialize, deserialize) {
+  Duplex.call(this, {objectMode: true});
+  this.serialize = common.wrapIgnoreNull(serialize);
+  this.deserialize = common.wrapIgnoreNull(deserialize);
+  this.call = call;
+  /* Status generated from reading messages from the server. Overrides the
+   * status from the server if not OK */
+  this.read_status = null;
+  /* Status received from the server. */
+  this.received_status = null;
+  this.on('finish', function() {
+    var batch = {};
+    batch[grpc.opType.SEND_CLOSE_FROM_CLIENT] = true;
+    call.startBatch(batch, function() {});
+  });
+}
+
+ClientDuplexStream.prototype._readsDone = _readsDone;
+ClientDuplexStream.prototype._receiveStatus = _receiveStatus;
+ClientDuplexStream.prototype._emitStatusIfDone = _emitStatusIfDone;
+ClientDuplexStream.prototype._read = _read;
+ClientDuplexStream.prototype._write = _write;
+
+/**
+ * Cancel the ongoing call
+ */
+function cancel() {
+  /* jshint validthis: true */
+  this.call.cancel();
+}
+
+ClientReadableStream.prototype.cancel = cancel;
+ClientWritableStream.prototype.cancel = cancel;
+ClientDuplexStream.prototype.cancel = cancel;
+
+/**
+ * Get the endpoint this call/stream is connected to.
+ * @return {string} The URI of the endpoint
+ */
+function getPeer() {
+  /* jshint validthis: true */
+  return this.call.getPeer();
+}
+
+ClientReadableStream.prototype.getPeer = getPeer;
+ClientWritableStream.prototype.getPeer = getPeer;
+ClientDuplexStream.prototype.getPeer = getPeer;
+
+/**
+ * Get a call object built with the provided options. Keys for options are
+ * 'deadline', which takes a date or number, and 'host', which takes a string
+ * and overrides the hostname to connect to.
+ * @param {Object} options Options map.
+ */
+function getCall(channel, method, options) {
+  var deadline;
+  var host;
+  var parent;
+  var propagate_flags;
+  var credentials;
+  if (options) {
+    deadline = options.deadline;
+    host = options.host;
+    parent = _.get(options, 'parent.call');
+    propagate_flags = options.propagate_flags;
+    credentials = options.credentials;
+  }
+  if (deadline === undefined) {
+    deadline = Infinity;
+  }
+  var call = new grpc.Call(channel, method, deadline, host,
+                           parent, propagate_flags);
+  if (credentials) {
+    call.setCredentials(credentials);
+  }
+  return call;
+}
+
+/**
+ * Get a function that can make unary requests to the specified method.
+ * @param {string} method The name of the method to request
+ * @param {function(*):Buffer} serialize The serialization function for inputs
+ * @param {function(Buffer)} deserialize The deserialization function for
+ *     outputs
+ * @return {Function} makeUnaryRequest
+ */
+function makeUnaryRequestFunction(method, serialize, deserialize) {
+  /**
+   * Make a unary request with this method on the given channel with the given
+   * argument, callback, etc.
+   * @this {Client} Client object. Must have a channel member.
+   * @param {*} argument The argument to the call. Should be serializable with
+   *     serialize
+   * @param {function(?Error, value=)} callback The callback to for when the
+   *     response is received
+   * @param {Metadata=} metadata Metadata to add to the call
+   * @param {Object=} options Options map
+   * @return {EventEmitter} An event emitter for stream related events
+   */
+  function makeUnaryRequest(argument, callback, metadata, options) {
+    /* jshint validthis: true */
+    var emitter = new EventEmitter();
+    var call = getCall(this.$channel, method, options);
+    if (metadata === null || metadata === undefined) {
+      metadata = new Metadata();
+    } else {
+      metadata = metadata.clone();
+    }
+    emitter.cancel = function cancel() {
+      call.cancel();
+    };
+    emitter.getPeer = function getPeer() {
+      return call.getPeer();
+    };
+    var client_batch = {};
+    var message = serialize(argument);
+    if (options) {
+      message.grpcWriteFlags = options.flags;
+    }
+    client_batch[grpc.opType.SEND_INITIAL_METADATA] =
+        metadata._getCoreRepresentation();
+    client_batch[grpc.opType.SEND_MESSAGE] = message;
+    client_batch[grpc.opType.SEND_CLOSE_FROM_CLIENT] = true;
+    client_batch[grpc.opType.RECV_INITIAL_METADATA] = true;
+    client_batch[grpc.opType.RECV_MESSAGE] = true;
+    client_batch[grpc.opType.RECV_STATUS_ON_CLIENT] = true;
+    call.startBatch(client_batch, function(err, response) {
+      response.status.metadata = Metadata._fromCoreRepresentation(
+          response.status.metadata);
+      var status = response.status;
+      var error;
+      var deserialized;
+      if (status.code === grpc.status.OK) {
+        if (err) {
+          // Got a batch error, but OK status. Something went wrong
+          callback(err);
+          return;
+        } else {
+          try {
+            deserialized = deserialize(response.read);
+          } catch (e) {
+            /* Change status to indicate bad server response. This will result
+             * in passing an error to the callback */
+            status = {
+              code: grpc.status.INTERNAL,
+              details: 'Failed to parse server response'
+            };
+          }
+        }
+      }
+      if (status.code !== grpc.status.OK) {
+        error = new Error(status.details);
+        error.code = status.code;
+        error.metadata = status.metadata;
+        callback(error);
+      } else {
+        callback(null, deserialized);
+      }
+      emitter.emit('status', status);
+      emitter.emit('metadata', Metadata._fromCoreRepresentation(
+          response.metadata));
+    });
+    return emitter;
+  }
+  return makeUnaryRequest;
+}
+
+/**
+ * Get a function that can make client stream requests to the specified method.
+ * @param {string} method The name of the method to request
+ * @param {function(*):Buffer} serialize The serialization function for inputs
+ * @param {function(Buffer)} deserialize The deserialization function for
+ *     outputs
+ * @return {Function} makeClientStreamRequest
+ */
+function makeClientStreamRequestFunction(method, serialize, deserialize) {
+  /**
+   * Make a client stream request with this method on the given channel with the
+   * given callback, etc.
+   * @this {Client} Client object. Must have a channel member.
+   * @param {function(?Error, value=)} callback The callback to for when the
+   *     response is received
+   * @param {Metadata=} metadata Array of metadata key/value pairs to add to the
+   *     call
+   * @param {Object=} options Options map
+   * @return {EventEmitter} An event emitter for stream related events
+   */
+  function makeClientStreamRequest(callback, metadata, options) {
+    /* jshint validthis: true */
+    var call = getCall(this.$channel, method, options);
+    if (metadata === null || metadata === undefined) {
+      metadata = new Metadata();
+    } else {
+      metadata = metadata.clone();
+    }
+    var stream = new ClientWritableStream(call, serialize);
+    var metadata_batch = {};
+    metadata_batch[grpc.opType.SEND_INITIAL_METADATA] =
+        metadata._getCoreRepresentation();
+    metadata_batch[grpc.opType.RECV_INITIAL_METADATA] = true;
+    call.startBatch(metadata_batch, function(err, response) {
+      if (err) {
+        // The call has stopped for some reason. A non-OK status will arrive
+        // in the other batch.
+        return;
+      }
+      stream.emit('metadata', Metadata._fromCoreRepresentation(
+          response.metadata));
+    });
+    var client_batch = {};
+    client_batch[grpc.opType.RECV_MESSAGE] = true;
+    client_batch[grpc.opType.RECV_STATUS_ON_CLIENT] = true;
+    call.startBatch(client_batch, function(err, response) {
+      response.status.metadata = Metadata._fromCoreRepresentation(
+          response.status.metadata);
+      var status = response.status;
+      var error;
+      var deserialized;
+      if (status.code === grpc.status.OK) {
+        if (err) {
+          // Got a batch error, but OK status. Something went wrong
+          callback(err);
+          return;
+        } else {
+          try {
+            deserialized = deserialize(response.read);
+          } catch (e) {
+            /* Change status to indicate bad server response. This will result
+             * in passing an error to the callback */
+            status = {
+              code: grpc.status.INTERNAL,
+              details: 'Failed to parse server response'
+            };
+          }
+        }
+      }
+      if (status.code !== grpc.status.OK) {
+        error = new Error(response.status.details);
+        error.code = status.code;
+        error.metadata = status.metadata;
+        callback(error);
+      } else {
+        callback(null, deserialized);
+      }
+      stream.emit('status', status);
+    });
+    return stream;
+  }
+  return makeClientStreamRequest;
+}
+
+/**
+ * Get a function that can make server stream requests to the specified method.
+ * @param {string} method The name of the method to request
+ * @param {function(*):Buffer} serialize The serialization function for inputs
+ * @param {function(Buffer)} deserialize The deserialization function for
+ *     outputs
+ * @return {Function} makeServerStreamRequest
+ */
+function makeServerStreamRequestFunction(method, serialize, deserialize) {
+  /**
+   * Make a server stream request with this method on the given channel with the
+   * given argument, etc.
+   * @this {SurfaceClient} Client object. Must have a channel member.
+   * @param {*} argument The argument to the call. Should be serializable with
+   *     serialize
+   * @param {Metadata=} metadata Array of metadata key/value pairs to add to the
+   *     call
+   * @param {Object} options Options map
+   * @return {EventEmitter} An event emitter for stream related events
+   */
+  function makeServerStreamRequest(argument, metadata, options) {
+    /* jshint validthis: true */
+    var call = getCall(this.$channel, method, options);
+    if (metadata === null || metadata === undefined) {
+      metadata = new Metadata();
+    } else {
+      metadata = metadata.clone();
+    }
+    var stream = new ClientReadableStream(call, deserialize);
+    var start_batch = {};
+    var message = serialize(argument);
+    if (options) {
+      message.grpcWriteFlags = options.flags;
+    }
+    start_batch[grpc.opType.SEND_INITIAL_METADATA] =
+        metadata._getCoreRepresentation();
+    start_batch[grpc.opType.RECV_INITIAL_METADATA] = true;
+    start_batch[grpc.opType.SEND_MESSAGE] = message;
+    start_batch[grpc.opType.SEND_CLOSE_FROM_CLIENT] = true;
+    call.startBatch(start_batch, function(err, response) {
+      if (err) {
+        // The call has stopped for some reason. A non-OK status will arrive
+        // in the other batch.
+        return;
+      }
+      stream.emit('metadata', Metadata._fromCoreRepresentation(
+          response.metadata));
+    });
+    var status_batch = {};
+    status_batch[grpc.opType.RECV_STATUS_ON_CLIENT] = true;
+    call.startBatch(status_batch, function(err, response) {
+      if (err) {
+        stream.emit('error', err);
+        return;
+      }
+      response.status.metadata = Metadata._fromCoreRepresentation(
+          response.status.metadata);
+      stream._receiveStatus(response.status);
+    });
+    return stream;
+  }
+  return makeServerStreamRequest;
+}
+
+/**
+ * Get a function that can make bidirectional stream requests to the specified
+ * method.
+ * @param {string} method The name of the method to request
+ * @param {function(*):Buffer} serialize The serialization function for inputs
+ * @param {function(Buffer)} deserialize The deserialization function for
+ *     outputs
+ * @return {Function} makeBidiStreamRequest
+ */
+function makeBidiStreamRequestFunction(method, serialize, deserialize) {
+  /**
+   * Make a bidirectional stream request with this method on the given channel.
+   * @this {SurfaceClient} Client object. Must have a channel member.
+   * @param {Metadata=} metadata Array of metadata key/value pairs to add to the
+   *     call
+   * @param {Options} options Options map
+   * @return {EventEmitter} An event emitter for stream related events
+   */
+  function makeBidiStreamRequest(metadata, options) {
+    /* jshint validthis: true */
+    var call = getCall(this.$channel, method, options);
+    if (metadata === null || metadata === undefined) {
+      metadata = new Metadata();
+    } else {
+      metadata = metadata.clone();
+    }
+    var stream = new ClientDuplexStream(call, serialize, deserialize);
+    var start_batch = {};
+    start_batch[grpc.opType.SEND_INITIAL_METADATA] =
+        metadata._getCoreRepresentation();
+    start_batch[grpc.opType.RECV_INITIAL_METADATA] = true;
+    call.startBatch(start_batch, function(err, response) {
+      if (err) {
+        // The call has stopped for some reason. A non-OK status will arrive
+        // in the other batch.
+        return;
+      }
+      stream.emit('metadata', Metadata._fromCoreRepresentation(
+          response.metadata));
+    });
+    var status_batch = {};
+    status_batch[grpc.opType.RECV_STATUS_ON_CLIENT] = true;
+    call.startBatch(status_batch, function(err, response) {
+      if (err) {
+        stream.emit('error', err);
+        return;
+      }
+      response.status.metadata = Metadata._fromCoreRepresentation(
+          response.status.metadata);
+      stream._receiveStatus(response.status);
+    });
+    return stream;
+  }
+  return makeBidiStreamRequest;
+}
+
+
+/**
+ * Map with short names for each of the requester maker functions. Used in
+ * makeClientConstructor
+ */
+var requester_makers = {
+  unary: makeUnaryRequestFunction,
+  server_stream: makeServerStreamRequestFunction,
+  client_stream: makeClientStreamRequestFunction,
+  bidi: makeBidiStreamRequestFunction
+};
+
+/**
+ * Creates a constructor for a client with the given methods. The methods object
+ * maps method name to an object with the following keys:
+ * path: The path on the server for accessing the method. For example, for
+ *     protocol buffers, we use "/service_name/method_name"
+ * requestStream: bool indicating whether the client sends a stream
+ * resonseStream: bool indicating whether the server sends a stream
+ * requestSerialize: function to serialize request objects
+ * responseDeserialize: function to deserialize response objects
+ * @param {Object} methods An object mapping method names to method attributes
+ * @param {string} serviceName The fully qualified name of the service
+ * @return {function(string, Object)} New client constructor
+ */
+exports.makeClientConstructor = function(methods, serviceName) {
+  /**
+   * Create a client with the given methods
+   * @constructor
+   * @param {string} address The address of the server to connect to
+   * @param {grpc.Credentials} credentials Credentials to use to connect
+   *     to the server
+   * @param {Object} options Options to pass to the underlying channel
+   */
+  function Client(address, credentials, options) {
+    if (!options) {
+      options = {};
+    }
+    /* Append the grpc-node user agent string after the application user agent
+     * string, and put the combination at the beginning of the user agent string
+     */
+    if (options['grpc.primary_user_agent']) {
+      options['grpc.primary_user_agent'] += ' ';
+    } else {
+      options['grpc.primary_user_agent'] = '';
+    }
+    options['grpc.primary_user_agent'] += 'grpc-node/' + version;
+    /* Private fields use $ as a prefix instead of _ because it is an invalid
+     * prefix of a method name */
+    this.$channel = new grpc.Channel(address, credentials, options);
+  }
+
+  _.each(methods, function(attrs, name) {
+    var method_type;
+    if (_.startsWith(name, '$')) {
+      throw new Error('Method names cannot start with $');
+    }
+    if (attrs.requestStream) {
+      if (attrs.responseStream) {
+        method_type = 'bidi';
+      } else {
+        method_type = 'client_stream';
+      }
+    } else {
+      if (attrs.responseStream) {
+        method_type = 'server_stream';
+      } else {
+        method_type = 'unary';
+      }
+    }
+    var serialize = attrs.requestSerialize;
+    var deserialize = attrs.responseDeserialize;
+    Client.prototype[name] = requester_makers[method_type](
+        attrs.path, serialize, deserialize);
+    // Associate all provided attributes with the method
+    _.assign(Client.prototype[name], attrs);
+  });
+
+  return Client;
+};
+
+/**
+ * Return the underlying channel object for the specified client
+ * @param {Client} client
+ * @return {Channel} The channel
+ */
+exports.getClientChannel = function(client) {
+  return client.$channel;
+};
+
+/**
+ * Wait for the client to be ready. The callback will be called when the
+ * client has successfully connected to the server, and it will be called
+ * with an error if the attempt to connect to the server has unrecoverablly
+ * failed or if the deadline expires. This function will make the channel
+ * start connecting if it has not already done so.
+ * @param {Client} client The client to wait on
+ * @param {(Date|Number)} deadline When to stop waiting for a connection. Pass
+ *     Infinity to wait forever.
+ * @param {function(Error)} callback The callback to call when done attempting
+ *     to connect.
+ */
+exports.waitForClientReady = function(client, deadline, callback) {
+  var checkState = function(err) {
+    if (err) {
+      callback(new Error('Failed to connect before the deadline'));
+      return;
+    }
+    var new_state = client.$channel.getConnectivityState(true);
+    if (new_state === grpc.connectivityState.READY) {
+      callback();
+    } else if (new_state === grpc.connectivityState.FATAL_FAILURE) {
+      callback(new Error('Failed to connect to server'));
+    } else {
+      client.$channel.watchConnectivityState(new_state, deadline, checkState);
+    }
+  };
+  checkState();
+};
+
+/**
+ * Creates a constructor for clients for the given service
+ * @param {ProtoBuf.Reflect.Service} service The service to generate a client
+ *     for
+ * @param {Object=} options Options to apply to the client
+ * @return {function(string, Object)} New client constructor
+ */
+exports.makeProtobufClientConstructor =  function(service, options) {
+  var method_attrs = common.getProtobufServiceAttrs(service, service.name,
+                                                    options);
+  var Client = exports.makeClientConstructor(
+      method_attrs, common.fullyQualifiedName(service));
+  Client.service = service;
+  Client.service.grpc_options = options;
+  return Client;
+};
+
+/**
+ * Map of status code names to status codes
+ */
+exports.status = grpc.status;
+
+/**
+ * See docs for client.callError
+ */
+exports.callError = grpc.callError;