建立连接

在介绍通信协议的时候，实际上服务侧对socket或者name_pipe的监听基本上也概括到了。

接下来客户侧连接上unix domain socket或者name_pipe，一个通信通道就建立完成了。

int searpc_named_pipe_client_connect(SearpcNamedPipeClient *client)
{
#if !defined(WIN32)
    client->pipe_fd = socket(AF_UNIX, SOCK_STREAM, 0);
    struct sockaddr_un servaddr;
    servaddr.sun_family = AF_UNIX;

    g_strlcpy (servaddr.sun_path, client->path, sizeof(servaddr.sun_path));
    if (connect(client->pipe_fd, (struct sockaddr *)&servaddr, (socklen_t)sizeof(servaddr)) < 0) {
        g_warning ("pipe client failed to connect to server: %s\n", strerror(errno));
        return -1;
    }

#else // !defined(WIN32)
    SearpcNamedPipe pipe_fd;
    pipe_fd = CreateFile(
        client->path,           // pipe name
        GENERIC_READ |          // read and write access
        GENERIC_WRITE,
        0,                      // no sharing
        NULL,                   // default security attributes
        OPEN_EXISTING,          // opens existing pipe
        0,                      // default attributes
        NULL);                  // no template file

    if (pipe_fd == INVALID_HANDLE_VALUE) {
        G_WARNING_WITH_LAST_ERROR("Failed to connect to named pipe");
        return -1;
    }

    DWORD mode = PIPE_READMODE_MESSAGE;
    if (!SetNamedPipeHandleState(pipe_fd, &mode, NULL, NULL)) {
        G_WARNING_WITH_LAST_ERROR("Failed to set named pipe mode");
        return -1;
    }

    client->pipe_fd = pipe_fd;

#endif // !defined(WIN32)

    /* g_debug ("pipe client connected to server\n"); */
    return 0;
}

class NamedPipeTransport(SearpcTransport):
    """
    This transport uses named pipes on windows and unix domain socket
    on linux/mac.

    It's compatible with the c implementation of named pipe transport.
    in lib/searpc-named-pipe-transport.[ch] files.

    The protocol is:
    - request: <32b length header><json request>
    - response: <32b length header><json response>
    """

    def __init__(self, socket_path):
        self.socket_path = socket_path
        self.pipe = None

    def connect(self):
        self.pipe = socket.socket(socket.AF_UNIX)
        self.pipe.connect(self.socket_path)

    def stop(self):
        if self.pipe:
            self.pipe.close()
            self.pipe = None

通道已建立完毕，接下来的就是在通道上进行数据的往来了。

seafile的web客户端就是通过python客户端与seafile-server的c服务端建立通道，进行消息通讯的。