This is a binding for ZMQ. Tested with Delphi7, BDS2006, and FPC 2.6.0. (Just in Windows for now).

The package contains a wrapper (zmq.pas) for the dll, and a higher level api (zmqapi.pas). It should work with ZMQ 2.2.0, and with 3.2.0 rc1 (experimental). To use the v3.2 dll, in zmq.inc define zmq3 (($define zmq3}). The dll's come from the official distro

You should use the higher level api, which'll save you a lot of time, and incidentally the code'll be easier to read.

First, you need to create a context

context := TZMQContext.Create; 

There are various socket types, see the Guide, each has a constant. To create for example a REP socket, just write this:

socket := context.Socket( stRep );

// binding the socket
socket.bind( 'tcp://*:5555' );

// connecting the socket
socket.connect( 'tcp://localhost:5555' );

To send messages the api has several methods. You can send single, or Multipart messages, in blocking or nonblocking (in the v3 it's called dontwait) mode.

// sending a string in blocking mode(default) is just as easy as this:
socket.send( 'Hello' );

// or in non-blocking mode
socket.send( 'Hello', [rsfNoBlock] );
// in this case if the message cannot be queued an EZMQException is raised,
// with a value EAGAIN.

// sending data from a stream (don't forget to set the position of the stream, to read to)
socket.send( stream, size );

// sending multipart messages.
// strings:
socket.send( ['Hello','World'] );

//this is equivalent to:
socket.send( 'Hello', [rsfSndMore] );
socket.send( 'World' );

// or use TStrings.
tsl := TStringList.Create;
tsl.Add( 'Hello' );
tsl.Add( 'World' );
socket.send( tsl );
tsl.Free;

Receiving messages is as easy as

msize := socket.recv( msg );
// the new message is in the msg, and msize holds the length of the message

// to a Stream
msize := socket.recv( stream );

// read multipart message
tsl := TStringList.Create;
mcount := socket.recv( tsl );
// this will add message parts to the stringlist, and returns
// the count of the messages received.

Monitoring Sockets ( just available in v3.2)

// define a callback like this.
procedure TMyClass.MonitorCallback( event: TZMQEvent );
begin
  // do something.
end;

// Register the callback
socket.RegisterMonitor( MonitorCallback, cZMQMonitorEventsAll );

// The `MonitorCallback` is called from a separate thread, created by `RegisterMonitor`

// you can deregister the monitoring with calling.
socket.DeRegisterMonitor; 

in the examples directory there are some examples translated from the guide.

• poll function of TZMQPoller has a new optional parameter "pollCount".

• Upgrade dll-s to v3.2.2 RC2

• New monitoring logic implemented.

• Default ZMQ version for the binding is now 3.2 ( can switch back to 2.2 by not defining zmq3 in the zmq.inc file )

• if poll returns ETERM the socket with the terminated context should be removed from the poll, and closed;
• zmq_stopwatch_stop returns the correct value, but on program exit there's an exception.
• if recv(string) recieves not a valid string ,but a binary data convert it to Hex.(not trivial, because String definition changes through delphi versions) (the identity.dpr is a test case)
• Decide the need of the zhelpers.h
• beter CTRL+C handling
• improve lruqueue2.dpr ( in client task CTRL+C handling)

The following people have contributed to the project:

Balazs Varga [email protected] Stathis Gkotsis [email protected] Stephane Carre [email protected]

Free use of this software is granted under the terms of the GNU Lesser General Public License (LGPL). For details see the files COPYING.LESSER included with the distribution.