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21 Abstract The manual page for the whole RMR library
22 Author E. Scott Daniels
27 .im &{lib}/man/setup.im
33 RMR -- Ric Message Router Library
36 RMR is a library which provides a user application with the ability
37 to send and receive messages to/from other RMR based applications
38 without having to understand the underlying messaging transport environment (e.g., SI95)
39 and without needing to know which other endpoint applications are currently
40 available and accepting messages.
41 To do this, RMR depends on a routing table generated by an external source.
42 This table is used to determine the destination endpoint of each message sent by mapping the
43 message type T (supplied by the user application) to an endpoint entry.
44 Once determined, the message is sent directly to the endpoint.
45 The user application is unaware of which endpoint actually receives the
46 message, and in some cases whether that message was sent to multiple
50 RMR functions do provide for the ability to respond to the specific source
51 instance of a message allowing for either a request response, or call
52 response relationship when needed.
56 The library must be given a route table which maps message numbers to
57 endpoint groups such that each time a message of type T is sent, the message
58 is delivered to one member of each group associated with T.
59 For example, message type 2 might route to two different groups where
60 group A consists of worker1 and worker2, while group B consists only of
64 It is the responsibility of the route table generator to know which endpoints
65 belong to which groups, and which groups accept which message types.
66 Once understood, the route table generator publishes a table that is ingested
67 by RMR and used for mapping messages to end points.
70 The following is a simple route table which causes message types 0 through 9 to
71 be routed to specific applications:
76 mse|1|-1|app10:4560,app11:4560
88 The special endpoint "%meid" indicates that the message type (0 in this case) is
89 to be routed to the endpoint which has been listed as the "owner" for the meid
90 appearing in the message.
91 MEID ownership is communicated to RMR using the same Route Table Manager interface
92 and by supplying a "table" such as the one below:
96 mme_ar | control1 | meid000 meid001 meid002 meid003 meid004 meid005
97 mme_ar | control2 | meid100 meid101 meid102 meid103
101 This table indicates that the application (endpoint) &ital(control1) "owns" 6 MEIDs
102 and &ital(control2) owns 4.
103 When message type 0 is sent, the MEID in the message will be used to select the
104 endpoint via this table.
107 The MEID table will update the existing owner relationships, and add new ones; it
108 is necessary to send only the changes with the add/replace (mme_ar) entries in
110 When necessary, MEIDs can be deleted by adding an &cw(mme_del) record to the table.
111 The following example illustrates how this might look:
115 mme_ar | control1 | meid000 meid001 meid002 meid003 meid004 meid005
116 mme_ar | control2 | meid100 meid101 meid102 meid103
117 mme_del| meid200 meid401
121 &h3(Route Table Syntax)
122 The following illustrates the syntax for both the route table.
127 mse | <message-type>[,<sender-endpoint>] | <sub-id> <roud-robin-grp>[;<round-robin-grp>]...
131 A round robin group is one or more endpoints from which one will be selected to receive
133 When multiple endpoints are given in a group, they must be separated with a comma.
134 An endpoint is the IP address and port (e.g. 192.158.4.30:8219) or DNS name and port of the
135 application that should receive the message type.
136 If multiple round-robin groups are given, they must be separated by a semicolon, and
139 The MEID map is similar to the route table.
140 Entries are used to add or replace the ownership of one or more MEIDs (mme_ar) or to
141 delete one or more MEIDs (mme_del).
142 The following is the syntax for the MEID map.
147 mme_ar | <owner-endpoint> | <meid> [<meid>...]
148 mme_del | <meid> [<meid>...]
149 meid_map | end | <count> [| <md5sum>
153 The <count> on the end record indicates the number of mme_ar and mme_del records
154 which were sent; if the count does not match the whole map is refused and dropped.
155 The <owner-endpoint> is the endpoint which should receive the message when a message
156 is routed based on the MEID it contains.
157 A MEID may be "owned" by only one endpoint, and if supplied multiple times, the last
158 observed relationship is used.
159 Each of the lists of MEIDs are blank separated.
162 The optional <md5sum> on the &ital(end) record should be the computed MD5 hash for all
163 records which appear between the start and and records.
164 This allows for a tighter verification that all data was received exactly as the
165 route manager transmitted them.
169 To enable configuration of the library behaviour outside of direct user application
170 control, RMR supports a number of environment variables which provide information
172 The following is a list of the various environment variables, what they control
173 and the defaults which RMR uses if undefined.
176 .** the list of environment vars supported
177 .im &{lib}/man/env_var_list.im
203 rmr_realloc_payload(3),