IDL for WebSocket Pepper API.

ppapi/api/dev/ppb_websocket_dev.idl

+/* Copyright (c) 2011 The Chromium Authors. All rights reserved.
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+/**
+ * This file defines the <code>PPB_WebSocket_Dev</code> interface.
+ */
+label Chrome {
+  M17 = 0.1
+};
+
+
+/**
+ * This enumeration contains the types representing the WebSocket ready state
+ * and these states are based on the JavaScript WebSocket API specification.
+ * GetReadyState() returns one of these states.
+ */
+[assert_size(4)]
+enum PP_WebSocketReadyState_Dev {
+  /**
+   * Ready state that the connection has not yet been established.
+   */
+  PP_WEBSOCKETREADYSTATE_CONNECTING_DEV = 0,
+
+  /**
+   * Ready state that the WebSocket connection is established and communication
+   * is possible.
+   */
+  PP_WEBSOCKETREADYSTATE_OPEN_DEV = 1,
+
+  /**
+   * Ready state that the connection is going through the closing handshake.
+   */
+  PP_WEBSOCKETREADYSTATE_CLOSING_DEV = 2,
+
+  /**
+   * Ready state that the connection has been closed or could not be opened.
+   */
+  PP_WEBSOCKETREADYSTATE_CLOSED_DEV = 3
+};
+
+/**
+ * This enumeration contains the types representing the WebSocket message type
+ * and these types are based on the JavaScript WebSocket API specification.
+ * ReceiveMessage() and SendMessage() use them as a parameter to represent
+ * handling message types.
+ */
+[assert_size(4)]
+enum PP_WebSocketMessageType_Dev {
+  /**
+   * Message type that represents a text message type.
+   */
+  PP_WEBSOCKET_MESSAGE_TYPE_TEXT_DEV = 0,
+
+  /**
+   * Message type that represents a binary message type.
+   */
+  PP_WEBSOCKET_MESSAGE_TYPE_BINARY_DEV = 1
+};
+
+[version=0.1, macro="PPB_WEBSOCKET_DEV_INTERFACE"]
+interface PPB_WebSocket_Dev {
+  /**
+   * Create() creates a WebSocket instance.
+   *
+   * @param[in] instance A <code>PP_Instance</code> identifying the instance
+   * with the WebSocket.
+   *
+   * @return A <code>PP_Resource</code> corresponding to a WebSocket if
+   * successful.
+   */
+  PP_Resource Create([in] PP_Instance instance);
+
+  /**
+   * IsWebSocket() determines if the provided <code>resource</code> is a
+   * WebSocket instance.
+   *
+   * @param[in] resource A <code>PP_Resource</code> corresponding to a
+   * WebSocket.
+   *
+   * @return Returns <code>PP_TRUE</code> if <code>resource</code> is a
+   * <code>PPB_WebSocket_Dev</code>, <code>PP_FALSE</code> if the
+   * <code>resource</code> is invalid or some type other than
+   * <code>PPB_WebSocket_Dev</code>.
+   */
+  PP_Bool IsWebSocket([in] PP_Resource resource);
+
+  /**
+   * Connect() connects to the specified WebSocket server. Caller can call this
+   * method at most once for a <code>web_socket</code>.
+   *
+   * @param[in] web_socket A <code>PP_Resource</code> corresponding to a
+   * WebSocket.
+   *
+   * @param[in] url A <code>PP_Var</code> representing a WebSocket server URL.
+   * The <code>PP_VarType</code> must be <code>PP_VARTYPE_STRING</code>.
+   *
+   * @param[in] protocols A pointer to an array of <code>PP_Var</code>
+   * specifying sub-protocols. Each <code>PP_Var</code> represents one
+   * sub-protocol and its <code>PP_VarType</code> must be
+   * <code>PP_VARTYPE_STRING</code>. This argument can be null only if
+   * <code>protocol_count</code> is 0.
+   *
+   * @param[in] protocol_count The number of sub-protocols in
+   * <code>protocols</code>.
+   *
+   * @param[in] callback A <code>PP_CompletionCallback</code> which is called
+   * when the connection is established or an error occurs in establishing
+   * connection.
+   *
+   * @return In case of immediate failure, returns an error code as follows.
+   * Returns <code>PP_ERROR_BADARGUMENT</code> corresponding to JavaScript
+   * SyntaxError and <code>PP_ERROR_NOACCESS</code> corresponding to JavaScript
+   * SecurityError. Otherwise, returns <code>PP_OK_COMPLETIONPENDING</code>
+   * and invokes <code>callback</code> later.
+   */
+  int32_t Connect([in] PP_Resource web_socket,
+                  [in] PP_Var url,
+                  [in, size_as=protocol_count] PP_Var[] protocols,
+                  [in] uint32_t protocol_count,
+                  [in] PP_CompletionCallback callback);
+
+  /**
+   * Close() closes the specified WebSocket connection by specifying
+   * <code>code</code> and <code>reason</code>.
+   *
+   * @param[in] web_socket A <code>PP_Resource</code> corresponding to a
+   * WebSocket.
+   *
+   * @param[in] code The WebSocket close code. Ignored if it is 0.
+   *
+   * @param[in] reason A <code>PP_Var</code> which represents the WebSocket
+   * close reason. Ignored if it is <code>PP_VARTYPE_UNDEFINED</code>.
+   * Otherwise, its <code>PP_VarType</code> must be
+   * <code>PP_VARTYPE_STRING</code>.
+   *
+   * @param[in] callback A <code>PP_CompletionCallback</code> which is called
+   * when the connection is closed or an error occurs in closing connection.
+   *
+   * @return In case of immediate failure, returns an error code as follows.
+   * Returns <code>PP_ERROR_BADARGUMENT</code> corresponding to JavaScript
+   * SyntaxError and <code>PP_ERROR_NOACCESS</code> corresponding to JavaScript
+   * InvalidAccessError. Otherwise, returns
+   * <code>PP_OK_COMPLETIONPENDING</code> and invokes <code>callback</code>
+   * later.
+   */
+  int32_t Close([in] PP_Resource web_socket,
+                [in] uint16_t code,
+                [in] PP_Var reason,
+                [in] PP_CompletionCallback callback);
+
+  /**
+   * ReceiveMessage() receives a message from the WebSocket server.
+   * This interface only returns bytes of a single message. That is, this
+   * interface must be called at least N times to receive N messages, no matter
+   * how small each message is.
+   *
+   * @param[in] web_socket A <code>PP_Resource</code> corresponding to a
+   * WebSocket.
+   *
+   * @param[out] message The received message is copied to provided
+   * <code>message</code>.
+   *
+   * @param[in] callback A <code>PP_CompletionCallback</code> which is called
+   * when the receiving message is completed. It is ignored when the function
+   * return <code>PP_OK</code>.
+   *
+   * @return In case of immediate failure, returns
+   * <code>PP_ERROR_FAILED</code>. If a message is currently available, returns
+   * <code>PP_OK</code>. Otherwise, returns <PP_OK_COMPLETIONPENDING</code>
+   * and invokes <code>callback</code> later. At that case, if GetReadyState()
+   * returns <code>PP_WEBSOCKETREADYSTATE_OPEN</code>, the received
+   * message is also copied to procided <code>message</code>. Otherwise,
+   * the connection is closed and ReceiveMessage() failed to receive a message.
+   */
+  int32_t ReceiveMessage([in] PP_Resource web_socket,
+                         [out] PP_Var message,
+                         [in] PP_CompletionCallback callback);

[dmichael (off chromium), 2011/11/10 17:32:33]

I mentioned before that I was a little worried about the performance of doing
the ReceiveMessage this way. Because you have to ask for the next message (over
IPC) after you've received a frame, you're guaranteeing that you have to wait
for an IPC round-trip between frames. With a PPP interface, you could always
push to the plugin without forcing that overhead between frames. I guess the
positive side to the API as-written is that the browser gets a better idea of
whether the plugin is keeping up.

I was hoping Darin would comment, since he has a lot of experience with
networking stuff :-/

I guess there's nothing in the API preventing the proxy from pushing data and
having it ready right away when ReceiveMessage is called, so maybe my concern
isn't really valid.

[Takashi Toyoshima, 2011/11/10 18:40:45]

Receiving data could be automatically transmitted via proxy/ipc to the pepper's
in-process buffer using the WebSocketChannelClient interface and so on. So I
think IPC round-trip could not happens usually.
If data is available, it returns the buffered data immediately without IPC,
otherwise the callback is invoked by half round-trip ipc and the next method
call can return the received data immediately.
If data is not available yet, the callback tell that

+
+  /**
+   * SendMessage() sends a message to the WebSocket server.
+   *
+   * @param[in] web_socket A <code>PP_Resource</code> corresponding to a
+   * WebSocket.
+   *
+   * @param[in] message A message to send. The message is copied to internal
+   * buffer. So caller can free <code>message</code> safely after returning
+   * from the function.
+   *
+   * @return In case of immediate failure, returns an error code as follows.
+   * Returns <code>PP_ERROR_FAILED</code> corresponding to JavaScript
+   * InvalidStateError and <code>PP_ERROR_BADARGUMENT</code> corresponding to
+   * JavaScript SyntaxError. Otherwise, return <code>PP_OK</code>.
+   * <code>PP_OK</code> doesn't necessarily mean that the server received the
+   * message.
+   */
+  int32_t SendMessage([in] PP_Resource web_socket,
+                      [in] PP_Var message);
+
+  /**
+   * GetBufferedAmount() returns the number of bytes of text and binary
+   * messages that have been queued for the WebSocket connection to send but
+   * have not been transmitted to the network yet.
+   *
+   * Note: This interface might not be able to return exact bytes in the first
+   * release. Current WebSocket implementation can not estimate exact protocol
+   * frame overheads.
+   *
+   * @param[in] web_socket A <code>PP_Resource</code> corresponding to a
+   * WebSocket.
+   *
+   * @return Returns the number of bytes.
+   */
+  uint64_t GetBufferedAmount([in] PP_Resource web_socket);
+
+  /**
+   * GetCloseCode() returns the connection close code for the WebSocket
+   * connection.
+   *
+   * @param[in] web_socket A <code>PP_Resource</code> corresponding to a
+   * WebSocket.
+   *
+   * @return Returns 0 if called before the close code is set.
+   */
+  uint16_t GetCloseCode([in] PP_Resource web_socket);
+
+  /**
+   * GetCloseReason() returns the connection close reason for the WebSocket
+   * connection.
+   *
+   * @param[in] web_socket A <code>PP_Resource</code> corresponding to a
+   * WebSocket.
+   *
+   * @return Returns a <code>PP_VARTYPE_NULL</code> var if called before the
+   * close reason is set, or <code>PP_VARTYPE_UNDEFINED</code> if called on an
+   * invalid resource.
+   */
+  PP_Var GetCloseReason([in] PP_Resource web_socket);
+
+  /**
+   * GetCloseWasClean() returns if the connection was closed cleanly for the
+   * specified WebSocket connection.
+   *
+   * @param[in] web_socket A <code>PP_Resource</code> corresponding to a
+   * WebSocket.
+   *
+   * @return Returns <code>PP_FALSE</code> if called before the connection is
+   * closed. Otherwise, returns <code>PP_TRUE</code> if the connection was
+   * closed cleanly and returns <code>PP_FALSE</code> if the connection was
+   * closed by abnormal reasons.
+   */
+  PP_Bool GetCloseWasClean([in] PP_Resource web_socket);
+
+  /**
+   * GetExtensions() returns the extensions selected by the server for the
+   * specified WebSocket connection.
+   *
+   * @param[in] web_socket A <code>PP_Resource</code> corresponding to a
+   * WebSocket.
+   *
+   * @return Returns a <code>PP_VARTYPE_STRING</code> var. If called before the
+   * connection is established or called on an invalid resource, its data is
+   * empty string.
+   * Currently its data is always empty string.
+   */
+  PP_Var GetExtensions([in] PP_Resource web_socket);
+
+  /**
+   * GetProtocol() returns the sub-protocol chosen by the server for the
+   * specified WebSocket connection.
+   *
+   * @param[in] web_socket A <code>PP_Resource</code> corresponding to a
+   * WebSocket.
+   *
+   * @return Returns a <code>PP_VARTYPE_STRING</code> var. If called before the
+   * connection is established, or called on an invalid resource, its data is
+   * empty string.
+   */
+  PP_Var GetProtocol([in] PP_Resource web_socket);
+
+  /**
+   * GetReadyState() returns the ready state of the specified WebSocket
+   * connection.
+   *
+   * @param[in] web_socket A <code>PP_Resource</code> corresponding to a
+   * WebSocket.
+   *
+   * @return Returns <code>PP_WEBSOCKETREADYSTATE_CONNECTING</code> if called
+   * before the connection is established.
+   */
+  PP_WebSocketReadyState_Dev GetReadyState([in] PP_Resource web_socket);
+
+  /**
+   * GetURL() returns the URL associated with specified WebSocket connection.
+   *
+   * @param[in] web_socket A <code>PP_Resource</code> corresponding to a
+   * WebSocket.
+   *
+   * @return Returns a <code>PP_VARTYPE_STRING</code> var. If called before the
+   * connection is established, or called on an invalid resource, its data is
+   * empty string.
+   */
+  PP_Var GetURL([in] PP_Resource web_socket);
+};