working with multipart messages Create a new empty message object Destroy a message object and all frames it contains Receive message from socket, returns zmsg_t object or NULL if the recv was interrupted. Does a blocking recv. If you want to not block then use the zloop class or zmsg_recv_nowait or zmq_poll to check for socket input before receiving. Send message to destination socket, and destroy the message after sending it successfully. If the message has no frames, sends nothing but destroys the message anyhow. Nullifies the caller's reference to the message (as it is a destructor). Send message to destination socket as part of a multipart sequence, and destroy the message after sending it successfully. Note that after a zmsg_sendm, you must call zmsg_send or another method that sends a final message part. If the message has no frames, sends nothing but destroys the message anyhow. Nullifies the caller's reference to the message (as it is a destructor). Return size of message, i.e. number of frames (0 or more). Return total size of all frames in message. Return message routing ID, if the message came from a ZMQ_SERVER socket. Else returns zero. Set routing ID on message. This is used if/when the message is sent to a ZMQ_SERVER socket. Push frame to the front of the message, i.e. before all other frames. Message takes ownership of frame, will destroy it when message is sent. Returns 0 on success, -1 on error. Deprecates zmsg_push, which did not nullify the caller's frame reference. Add frame to the end of the message, i.e. after all other frames. Message takes ownership of frame, will destroy it when message is sent. Returns 0 on success. Deprecates zmsg_add, which did not nullify the caller's frame reference. Remove first frame from message, if any. Returns frame, or NULL. Push block of memory to front of message, as a new frame. Returns 0 on success, -1 on error. Add block of memory to the end of the message, as a new frame. Returns 0 on success, -1 on error. Push string as new frame to front of message. Returns 0 on success, -1 on error. Push string as new frame to end of message. Returns 0 on success, -1 on error. Push formatted string as new frame to front of message. Returns 0 on success, -1 on error. Push formatted string as new frame to end of message. Returns 0 on success, -1 on error. Pop frame off front of message, return as fresh string. If there were no more frames in the message, returns NULL. Push encoded message as a new frame. Message takes ownership of submessage, so the original is destroyed in this call. Returns 0 on success, -1 on error. Remove first submessage from message, if any. Returns zmsg_t, or NULL if decoding was not successful. Remove specified frame from list, if present. Does not destroy frame. Set cursor to first frame in message. Returns frame, or NULL, if the message is empty. Use this to navigate the frames as a list. Return the next frame. If there are no more frames, returns NULL. To move to the first frame call zmsg_first(). Advances the cursor. Return the last frame. If there are no frames, returns NULL. Save message to an open file, return 0 if OK, else -1. The message is saved as a series of frames, each with length and data. Note that the file is NOT guaranteed to be portable between operating systems, not versions of CZMQ. The file format is at present undocumented and liable to arbitrary change. Load/append an open file into new message, return the message. Returns NULL if the message could not be loaded. Serialize multipart message to a single message frame. Use this method to send structured messages across transports that do not support multipart data. Allocates and returns a new frame containing the serialized message. To decode a serialized message frame, use zmsg_decode (). Decodes a serialized message frame created by zmsg_encode () and returns a new zmsg_t object. Returns NULL if the frame was badly formatted or there was insufficient memory to work. Create copy of message, as new message object. Returns a fresh zmsg_t object. If message is null, or memory was exhausted, returns null. Send message to zsys log sink (may be stdout, or system facility as configured by zsys_set_logstream). Return true if the two messages have the same number of frames and each frame in the first message is identical to the corresponding frame in the other message. As with zframe_eq, return false if either message is NULL. Generate a signal message encoding the given status. A signal is a short message carrying a 1-byte success/failure code (by convention, 0 means OK). Signals are encoded to be distinguishable from "normal" messages. Return signal value, 0 or greater, if message is a signal, -1 if not. Probe the supplied object, and report if it looks like a zmsg_t.