1ZFRAME(3)                         CZMQ Manual                        ZFRAME(3)
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NAME

6       zframe - Class for working with single message frames
7

SYNOPSIS

9       //  This is a stable class, and may not change except for emergencies. It
10       //  is provided in stable builds.
11       //  This class has draft methods, which may change over time. They are not
12       //  in stable releases, by default. Use --enable-drafts to enable.
13       #define ZFRAME_MORE 1                       //
14       #define ZFRAME_REUSE 2                      //
15       #define ZFRAME_DONTWAIT 4                   //
16
17       //  Create a new frame. If size is not null, allocates the frame data
18       //  to the specified size. If additionally, data is not null, copies
19       //  size octets from the specified data into the frame body.
20       CZMQ_EXPORT zframe_t *
21           zframe_new (const void *data, size_t size);
22
23       //  Create an empty (zero-sized) frame
24       CZMQ_EXPORT zframe_t *
25           zframe_new_empty (void);
26
27       //  Create a frame with a specified string content.
28       CZMQ_EXPORT zframe_t *
29           zframe_from (const char *string);
30
31       //  Receive frame from socket, returns zframe_t object or NULL if the recv
32       //  was interrupted. Does a blocking recv, if you want to not block then use
33       //  zpoller or zloop.
34       CZMQ_EXPORT zframe_t *
35           zframe_recv (void *source);
36
37       //  Destroy a frame
38       CZMQ_EXPORT void
39           zframe_destroy (zframe_t **self_p);
40
41       //  Send a frame to a socket, destroy frame after sending.
42       //  Return -1 on error, 0 on success.
43       CZMQ_EXPORT int
44           zframe_send (zframe_t **self_p, void *dest, int flags);
45
46       //  Return number of bytes in frame data
47       CZMQ_EXPORT size_t
48           zframe_size (zframe_t *self);
49
50       //  Return address of frame data
51       CZMQ_EXPORT byte *
52           zframe_data (zframe_t *self);
53
54       //  Return meta data property for frame
55       //  The caller shall not modify or free the returned value, which shall be
56       //  owned by the message.
57       CZMQ_EXPORT const char *
58           zframe_meta (zframe_t *self, const char *property);
59
60       //  Create a new frame that duplicates an existing frame. If frame is null,
61       //  or memory was exhausted, returns null.
62       //  Caller owns return value and must destroy it when done.
63       CZMQ_EXPORT zframe_t *
64           zframe_dup (zframe_t *self);
65
66       //  Return frame data encoded as printable hex string, useful for 0MQ UUIDs.
67       //  Caller must free string when finished with it.
68       //  Caller owns return value and must destroy it when done.
69       CZMQ_EXPORT char *
70           zframe_strhex (zframe_t *self);
71
72       //  Return frame data copied into freshly allocated string
73       //  Caller must free string when finished with it.
74       //  Caller owns return value and must destroy it when done.
75       CZMQ_EXPORT char *
76           zframe_strdup (zframe_t *self);
77
78       //  Return TRUE if frame body is equal to string, excluding terminator
79       CZMQ_EXPORT bool
80           zframe_streq (zframe_t *self, const char *string);
81
82       //  Return frame MORE indicator (1 or 0), set when reading frame from socket
83       //  or by the zframe_set_more() method
84       CZMQ_EXPORT int
85           zframe_more (zframe_t *self);
86
87       //  Set frame MORE indicator (1 or 0). Note this is NOT used when sending
88       //  frame to socket, you have to specify flag explicitly.
89       CZMQ_EXPORT void
90           zframe_set_more (zframe_t *self, int more);
91
92       //  Return TRUE if two frames have identical size and data
93       //  If either frame is NULL, equality is always false.
94       CZMQ_EXPORT bool
95           zframe_eq (zframe_t *self, zframe_t *other);
96
97       //  Set new contents for frame
98       CZMQ_EXPORT void
99           zframe_reset (zframe_t *self, const void *data, size_t size);
100
101       //  Send message to zsys log sink (may be stdout, or system facility as
102       //  configured by zsys_set_logstream). Prefix shows before frame, if not null.
103       CZMQ_EXPORT void
104           zframe_print (zframe_t *self, const char *prefix);
105
106       //  Probe the supplied object, and report if it looks like a zframe_t.
107       CZMQ_EXPORT bool
108           zframe_is (void *self);
109
110       //  Self test of this class.
111       CZMQ_EXPORT void
112           zframe_test (bool verbose);
113
114       #ifdef CZMQ_BUILD_DRAFT_API
115       //  *** Draft method, for development use, may change without warning ***
116       //  Return frame routing ID, if the frame came from a ZMQ_SERVER socket.
117       //  Else returns zero.
118       CZMQ_EXPORT uint32_t
119           zframe_routing_id (zframe_t *self);
120
121       //  *** Draft method, for development use, may change without warning ***
122       //  Set routing ID on frame. This is used if/when the frame is sent to a
123       //  ZMQ_SERVER socket.
124       CZMQ_EXPORT void
125           zframe_set_routing_id (zframe_t *self, uint32_t routing_id);
126
127       //  *** Draft method, for development use, may change without warning ***
128       //  Return frame group of radio-dish pattern.
129       CZMQ_EXPORT const char *
130           zframe_group (zframe_t *self);
131
132       //  *** Draft method, for development use, may change without warning ***
133       //  Set group on frame. This is used if/when the frame is sent to a
134       //  ZMQ_RADIO socket.
135       //  Return -1 on error, 0 on success.
136       CZMQ_EXPORT int
137           zframe_set_group (zframe_t *self, const char *group);
138
139       #endif // CZMQ_BUILD_DRAFT_API
140       Please add '@interface' section in './../src/zframe.c'.
141

DESCRIPTION

143       The zframe class provides methods to send and receive single message
144       frames across 0MQ sockets. A frame corresponds to one zmq_msg_t. When
145       you read a frame from a socket, the zframe_more() method indicates if
146       the frame is part of an unfinished multipart message. The zframe_send
147       method normally destroys the frame, but with the ZFRAME_REUSE flag, you
148       can send the same frame many times. Frames are binary, and this class
149       has no special support for text data.
150
151       Please add @discuss section in ./../src/zframe.c.
152

EXAMPLE

154       From zframe_test method.
155
156           //  Create two PAIR sockets and connect over inproc
157           zsock_t *output = zsock_new (ZMQ_PAIR);
158           assert (output);
159           int port = zsock_bind (output, "tcp://127.0.0.1:*");
160           assert (port != -1);
161           zsock_t *input = zsock_new (ZMQ_PAIR);
162           assert (input);
163           rc = zsock_connect (input, "tcp://127.0.0.1:%d", port);
164           assert (rc != -1);
165
166           //  Send five different frames, test ZFRAME_MORE
167           int frame_nbr;
168           for (frame_nbr = 0; frame_nbr < 5; frame_nbr++) {
169               frame = zframe_new ("Hello", 5);
170               assert (frame);
171               rc = zframe_send (&frame, output, ZFRAME_MORE);
172               assert (rc == 0);
173           }
174           //  Send same frame five times, test ZFRAME_REUSE
175           frame = zframe_new ("Hello", 5);
176           assert (frame);
177           for (frame_nbr = 0; frame_nbr < 5; frame_nbr++) {
178               rc = zframe_send (&frame, output, ZFRAME_MORE + ZFRAME_REUSE);
179               assert (rc == 0);
180           }
181           assert (frame);
182           zframe_t *copy = zframe_dup (frame);
183           assert (zframe_eq (frame, copy));
184           zframe_destroy (&frame);
185           assert (!zframe_eq (frame, copy));
186           assert (zframe_size (copy) == 5);
187           zframe_destroy (&copy);
188           assert (!zframe_eq (frame, copy));
189
190           //  Test zframe_new_empty
191           frame = zframe_new_empty ();
192           assert (frame);
193           assert (zframe_size (frame) == 0);
194           zframe_destroy (&frame);
195
196           //  Send END frame
197           frame = zframe_new ("NOT", 3);
198           assert (frame);
199           zframe_reset (frame, "END", 3);
200           char *string = zframe_strhex (frame);
201           assert (streq (string, "454E44"));
202           freen (string);
203           string = zframe_strdup (frame);
204           assert (streq (string, "END"));
205           freen (string);
206           rc = zframe_send (&frame, output, 0);
207           assert (rc == 0);
208
209           //  Read and count until we receive END
210           frame_nbr = 0;
211           for (frame_nbr = 0;; frame_nbr++) {
212               zframe_t *frame = zframe_recv (input);
213               if (zframe_streq (frame, "END")) {
214                   zframe_destroy (&frame);
215                   break;
216               }
217               assert (zframe_more (frame));
218               zframe_set_more (frame, 0);
219               assert (zframe_more (frame) == 0);
220               zframe_destroy (&frame);
221           }
222           assert (frame_nbr == 10);
223
224           #if (ZMQ_VERSION >= ZMQ_MAKE_VERSION (4, 1, 0))
225           // Test zframe_meta
226           frame = zframe_new ("Hello", 5);
227           assert (frame);
228           rc = zframe_send (&frame, output, 0);
229           assert (rc == 0);
230           frame = zframe_recv (input);
231           const char *meta = zframe_meta (frame, "Socket-Type");
232           assert (meta != NULL);
233           assert (streq (meta, "PAIR"));
234           assert (zframe_meta (frame, "nonexistent") == NULL);
235           zframe_destroy (&frame);
236           #endif
237
238           zsock_destroy (&input);
239           zsock_destroy (&output);
240
241           #if defined (ZMQ_SERVER)
242           //  Create server and client sockets and connect over inproc
243           zsock_t *server = zsock_new_server ("inproc://zframe-test-routing");
244           assert (server);
245           zsock_t *client = zsock_new_client ("inproc://zframe-test-routing");
246           assert (client);
247
248           //  Send request from client to server
249           zframe_t *request = zframe_new ("Hello", 5);
250           assert (request);
251           rc = zframe_send (&request, client, 0);
252           assert (rc == 0);
253           assert (!request);
254
255           //  Read request and send reply
256           request = zframe_recv (server);
257           assert (request);
258           assert (zframe_streq (request, "Hello"));
259           assert (zframe_routing_id (request));
260
261           zframe_t *reply = zframe_new ("World", 5);
262           assert (reply);
263           zframe_set_routing_id (reply, zframe_routing_id (request));
264           rc = zframe_send (&reply, server, 0);
265           assert (rc == 0);
266           zframe_destroy (&request);
267
268           //  Read reply
269           reply = zframe_recv (client);
270           assert (zframe_streq (reply, "World"));
271           assert (zframe_routing_id (reply) == 0);
272           zframe_destroy (&reply);
273
274           //  Client and server disallow multipart
275           frame = zframe_new ("Hello", 5);
276           rc = zframe_send (&frame, client, ZFRAME_MORE);
277           assert (rc == -1);
278           rc = zframe_send (&frame, server, ZFRAME_MORE);
279           assert (rc == -1);
280           zframe_destroy (&frame);
281
282           zsock_destroy (&client);
283           zsock_destroy (&server);
284           #endif
285
286           #ifdef ZMQ_RADIO
287           //  Create radio and dish sockets and connect over inproc
288           zsock_t *radio = zsock_new_radio ("inproc://zframe-test-radio");
289           assert (radio);
290           zsock_t *dish = zsock_new_dish ("inproc://zframe-test-radio");
291           assert (dish);
292
293           //  Join the group
294           rc = zsock_join (dish, "World");
295           assert (rc == 0);
296
297           //  Publish message from radio
298           zframe_t *message = zframe_new ("Hello", 5);
299           assert (message);
300           rc = zframe_set_group (message, "World");
301           assert (rc == 0);
302           rc = zframe_send (&message, radio, 0);
303           assert (rc == 0);
304           assert (!message);
305
306           //  Receive the message from dish
307           message = zframe_recv (dish);
308           assert (message);
309           assert (zframe_streq (message, "Hello"));
310           assert (strcmp("World", zframe_group (message)) == 0);
311           zframe_destroy (&message);
312
313           zsock_destroy (&dish);
314           zsock_destroy (&radio);
315           #else
316           frame = zframe_new ("Hello", 5);
317           rc = zframe_set_group (frame, "World");
318           assert(rc == -1);
319           assert(errno == ENOTSUP);
320           zframe_destroy (&frame);
321           #endif
322
323           #if defined (__WINDOWS__)
324           zsys_shutdown();
325           #endif
326
327

AUTHORS

329       The czmq manual was written by the authors in the AUTHORS file.
330

RESOURCES

332       Main web site:
333
334       Report bugs to the email <zeromq-dev@lists.zeromq.org[1]>
335
337       Copyright (c) the Contributors as noted in the AUTHORS file. This file
338       is part of CZMQ, the high-level C binding for 0MQ:
339       http://czmq.zeromq.org. This Source Code Form is subject to the terms
340       of the Mozilla Public License, v. 2.0. If a copy of the MPL was not
341       distributed with this file, You can obtain one at
342       http://mozilla.org/MPL/2.0/. LICENSE included with the czmq
343       distribution.
344

NOTES

346        1. zeromq-dev@lists.zeromq.org
347           mailto:zeromq-dev@lists.zeromq.org
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351CZMQ 4.1.1                        07/24/2019                         ZFRAME(3)
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