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10 ============================================================================================
14 ============================================================================================
18 --------------------------------------------------------------------------------------------
20 RMr -- Ric Message Router Library
23 --------------------------------------------------------------------------------------------
25 RMr is a library which provides a user application with the
26 ability to send and receive messages to/from other RMr based
27 applications without having to understand the underlying
28 messaging transport environment (e.g. Nanomsg) and without
29 needing to know which other endpoint applications are
30 currently available and accepting messages. To do this, RMr
31 depends on a routing table generated by an external source.
32 This table is used to determine the destination endpoint of
33 each message sent by mapping the message type T (supplied by
34 the user application) to an endpoint entry. Once determined,
35 the message is sent directly to the endpoint. The user
36 application is unaware of which endpoint actually receives
37 the message, and in some cases whether that message was sent
38 to multiple applications.
40 RMr functions do provide for the ability to respond to the
41 specific source instance of a message allowing for either a
42 request response, or call response relationship when needed.
45 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
47 The library must be given a route table which maps message
48 numbers to endpoint groups such that each time a message of
49 type T is sent, the message is delivered to one member of
50 each group associated with T. For example, message type 2
51 might route to two different groups where group A consists of
52 worker1 and worker2, while group B consists only of logger1.
54 It is the responsibility of the route table generator to know
55 which endpoints belong to which groups, and which groups
56 accept which message types. Once understood, the route table
57 generator publishes a table that is ingested by RMr and used
58 for mapping messages to end points.
60 The following is a simple route table which causes message
61 types 0 through 9 to be routed to specific applications:
67 mse|1|-1|app10:4560,app11:4560
80 The special endpoint "%meid" indicates that the message type
81 (0 in this case) is to be routed to the endpoint which has
82 been listed as the "owner" for the meid appearing in the
83 message. MEID ownership is communicated to RMR using the same
84 Route Table Manager interface and by supplying a "table" such
90 mme_ar | control1 | meid000 meid001 meid002 meid003 meid004 meid005
91 mme_ar | control2 | meid100 meid101 meid102 meid103
95 This table indicates that the application (endpoint)
96 *control1* "owns" 6 MEIDs and *control2* owns 4. When message
97 type 0 is sent, the MEID in the message will be used to
98 select the endpoint via this table.
100 The MEID table will update the existing owner relationships,
101 and add new ones; it is necessary to send only the changes
102 with the add/replace (mme_ar) entries in the table. When
103 necessary, MEIDs can be deleted by adding an mme_del record
104 to the table. The following example illustrates how this
110 mme_ar | control1 | meid000 meid001 meid002 meid003 meid004 meid005
111 mme_ar | control2 | meid100 meid101 meid102 meid103
112 mme_del| meid200 meid401
118 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
120 The following illustrates the syntax for both the route
127 mse | <message-type>[,<sender-endpoint>] | <sub-id> <roud-robin-grp>[;<round-robin-grp>]...
132 A round robin group is one or more endpoints from which one
133 will be selected to receive the message. When multiple
134 endpoints are given in a group, they must be separated with a
135 comma. An endpoint is the IP address and port (e.g.
136 192.158.4.30:8219) or DNS name and port of the application
137 that should receive the message type. If multiple round-robin
138 groups are given, they must be separated by a semicolon, and
141 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
143 The MEID map is similar to the route table. Entries are used
144 to add or replace the ownership of one or more MEIDs (mme_ar)
145 or to delete one or more MEIDs (mme_del). The following is
146 the syntax for the MEID map.
152 mme_ar | <owner-endpoint> | <meid> [<meid>...]
153 mme_del | <meid> [<meid>...]
154 meid_map | end | <count>
158 The <count> on the end record indicates the number of mme_ar
159 and mme_del records which were sent; if the count does not
160 match the whole map is refused and dropped. The
161 <owner-endpoint> is the endpoint which should receive the
162 message when a message is routed based on the MEID it
163 contains. A MEID may be "owned" by only one endpoint, and if
164 supplied multiple times, the last observed relationship is
165 used. Each of the lists of MEIDs are blank separated.
168 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
170 To enable configuration of the library behaviour outside of
171 direct user application control, RMr supports a number of
172 environment variables which provide information to the
173 library. The following is a list of the various environment
174 variables, what they control and the defaults which RMr uses
181 Allows the asynch connection mode to be turned off (by
182 setting the value to 0. When set to 1, or missing from the
183 environment, RMR will invoke the connection interface in
184 the transport mechanism using the non-blocking (asynch)
185 mode. This will likely result in many "soft failures"
186 (retry) until the connection is established, but allows
187 the application to continue unimpeeded should the
188 connection be slow to set up.
192 This provides the interface that RMr will bind listen
193 ports to allowing for a single interface to be used rather
194 than listening across all interfaces. This should be the
195 IP address assigned to the interface that RMr should
196 listen on, and if not defined RMr will listen on all
201 RMr opens a TCP listen socket using the port defined by
202 this environment variable and expects that the route table
203 generator process will connect to this port. If not
204 supplied the port 4561 is used.
208 Is set to 1 if the route table generator is sending
209 "plain" messages (not using RMr to send messages, 0 if the
210 rtg is using RMr to send. The default is 1 as we don't
211 expect the rtg to use RMr.
215 This is used to supply a static route table which can be
216 used for debugging, testing, or if no route table
217 generator process is being used to supply the route table.
218 If not defined, no static table is used and RMr will not
219 report *ready* until a table is received. The static route
220 table may contain both the route table (between newrt
221 start and end records), and the MEID map (between meid_map
222 start and end records)
226 This is either the name or IP address which is placed into
227 outbound messages as the message source. This will used
228 when an RMR based application uses the rmr_rts_msg()
229 function to return a response to the sender. If not
230 supplied RMR will use the hostname which in some container
231 environments might not be routable.
235 This supplies the name of a verbosity control file. The
236 core RMR functions do not produce messages unless there is
237 a critical failure. However, the route table collection
238 thread, not a part of the main message processing
239 component, can write additional messages to standard
240 error. If this variable is set, RMR will extract the
241 verbosity level for these messages (0 is silent) from the
242 first line of the file. Changes to the file are detected
243 and thus the level can be changed dynamically, however RMR
244 will only suss out this variable during initialisation, so
245 it is impossible to enable verbosity after startup.
249 If set to 1, RMR will write some warnings which are
250 non-performance impacting. If the variable is not defined,
251 or set to 0, RMR will not write these additional warnings.
255 --------------------------------------------------------------------------------------------
257 rmr_alloc_msg(3), rmr_tralloc_msg(3), rmr_call(3),
258 rmr_free_msg(3), rmr_init(3), rmr_init_trace(3),
259 rmr_get_meid(3), rmr_get_src(3), rmr_get_srcip(3),
260 rmr_get_trace(3), rmr_get_trlen(3), rmr_get_xact(3),
261 rmr_payload_size(3), rmr_rcv_msg(3), rmr_rcv_specific(3),
262 rmr_rts_msg(3), rmr_ready(3), rmr_fib(3), rmr_has_str(3),
263 rmr_tokenise(3), rmr_mk_ring(3), rmr_realloc_payload(3),
264 rmr_ring_free(3), rmr_set_trace(3), rmr_torcv_msg(3),
265 rmr_wh_open(3), rmr_wh_send_msg(3)