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Zeromq package: Difference between revisions
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>> pkg load zeromq | >> pkg load zeromq | ||
Look at the quick reference for the package: | |||
>> help zeromq | |||
[[Category:Octave | == Differences between C and Octave bindings == | ||
The Octave binding is a subset of the C binding of the ZeroMQ library. | |||
Major differences are: | |||
1. The octave binding creates a single zeromq context that is used for all zeromq sockets. In the C bindings, the programmer must create a context and use it during socket creation. | |||
2. only limited zmq_getsockopt and zmq_setsockopt is currently implemented. | |||
3. functions mostly return true or false for whether they succeeded or failed. In the C binding, 0 signified success. | |||
== The functions == | |||
zmq_bind | |||
Bind a zeromq socket to a endpoint. | |||
zmq_close | |||
Close a zeromq socket. | |||
zmq_connect | |||
Connect a zeromq socket to a endpoint | |||
zmq_errno | |||
Get system errno value. | |||
zmq_getsockopt | |||
Get current value of a zeromq socket option. | |||
zmq_poll | |||
Poll a socket or sockets for a timeout or incoming data | |||
available. | |||
zmq_recv | |||
Attempt to read data from a zeromq socket. | |||
zmq_send | |||
Attempt to send data from a zeromq socket. | |||
zmq_setsockopt | |||
Set a zeromq socket option. | |||
zmq_strerror | |||
Get the last zmq error string. | |||
zmq_unbind | |||
Unbind a previously bound zeromq socket. | |||
zmq_version | |||
Get the zeromq library version numbers. | |||
= Examples = | |||
The zeromq package comes with a number of examples included in it. They can be opened in octave using: | |||
>> edit examples/zmq_example1.m | |||
== basic request/reply pattern == | |||
Example based on client/server example from [http://zguide.zeromq.org/page:all#Ask-and-Ye-Shall-Receive http://zguide.zeromq.org/page:all#Ask-and-Ye-Shall-Receive] | |||
The client sends a "Hello" to the server which responds back "World". No error checking or data validation is done in the example. | |||
{{Code|Server code|<syntaxhighlight lang="octave" style="font-size:13px"> | |||
% zeromq package must be installed and loaded to work | |||
pkg load zeromq | |||
% dont buffer output | |||
more off | |||
printf ("Creating hello world server...\n"); | |||
% create reply socket, and bind it to port 5555 | |||
sock = zmq_socket (ZMQ_REP); | |||
zmq_bind (sock, "tcp://*:5555"); | |||
printf ("Waiting for clients ...\n"); | |||
% loop forever, waiting for client requests and responding back | |||
while (true) | |||
recievedata = zmq_recv (sock, 10, 0); | |||
printf ("Received Hello\n"); | |||
zmq_send (sock, "World", 5, 0); | |||
endwhile | |||
</syntaxhighlight>}} | |||
{{Code|Client code|<syntaxhighlight lang="octave" style="font-size:13px"> | |||
% zeromq package must be installed and loaded to work | |||
pkg load zeromq | |||
% dont buffer output | |||
more off | |||
printf ("Connecting to hello world server...\n"); | |||
% Create socket and connect to server | |||
sock = zmq_socket (ZMQ_REQ); | |||
zmq_connect (sock, "tcp://localhost:5555"); | |||
for request_nbr = [1:10] | |||
printf ("Sending Hello %d...\n", request_nbr); | |||
zmq_send (sock, uint8("Hello"), 5, 0); | |||
% try to read up to 10 bytes of reply data. | |||
printf ("Waiting for server response %d... (Ctrl-C to exit)\n", request_nbr); | |||
recieved = zmq_recv (sock, 10, 0); | |||
printf ("Received World %d\n", request_nbr); | |||
endfor | |||
zmq_close (sock); | |||
</syntaxhighlight>}} | |||
== basic publish/subscribe pattern == | |||
Example based on client/server example from [http://zguide.zeromq.org/page:all#Getting-the-Message-Out http://zguide.zeromq.org/page:all#Getting-the-Message-Out] | |||
The server pushes 'weather updates' for random zipcodes. The client subscribes to the server just for zipcode 10001. | |||
{{Code|Server code|<syntaxhighlight lang="octave" style="font-size:13px"> | |||
% zeromq package must be installed and loaded to work | |||
pkg load zeromq | |||
% dont buffer output | |||
more off | |||
publisher = zmq_socket (ZMQ_PUB); | |||
rc = zmq_bind (publisher, "tcp://*:5556"); | |||
assert (rc); | |||
while (true) | |||
% Get values that will fool the boss | |||
zipcode = 10000 + randi (20); | |||
temperature = randi (215) - 80; | |||
relhumidity = randi (50) + 10; | |||
% Send message to all subscribers | |||
update = sprintf ("%05d %d %d", zipcode, temperature, relhumidity); | |||
zmq_send (publisher, update); | |||
endwhile | |||
zmq_close (publisher); | |||
</syntaxhighlight>}} | |||
{{Code|Client code|<syntaxhighlight lang="octave" style="font-size:13px"> | |||
% zeromq package must be installed and loaded to work | |||
pkg load zeromq | |||
% dont buffer output | |||
more off | |||
subscriber = zmq_socket (ZMQ_SUB); | |||
rc = zmq_connect (subscriber, "tcp://localhost:5556"); | |||
assert (rc); | |||
% Subscribe to zipcode, default is NYC, 10001 | |||
zipfilter = "10001 "; | |||
rc = zmq_setsockopt (subscriber, ZMQ_SUBSCRIBE, zipfilter); | |||
assert (rc); | |||
% Process 100 updates | |||
update_nbr = 0; | |||
total_temp = 0; | |||
for update_nbr = 1:100 | |||
string = char( zmq_recv(subscriber, 128) ); | |||
[zipcode, temperature, relhumidity, count, errmsg] = sscanf (string, "%d %d %d", "C"); | |||
fprintf ("recieved a temp for zipcode '%s' of %dF\n", ... | |||
zipfilter, temperature); | |||
total_temp += temperature; | |||
endfor | |||
fprintf ("Average temperature for zipcode '%s' was %dF\n", ... | |||
zipfilter, (total_temp / update_nbr)); | |||
zmq_close (subscriber); | |||
</syntaxhighlight>}} | |||
[[Category:Octave Forge]] | |||