.if false ================================================================================== Copyright (c) 2019-2020 Nokia Copyright (c) 2018-2020 AT&T Intellectual Property. Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at http://www.apache.org/licenses/LICENSE-2.0 Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License. ================================================================================== .fi .if false Mnemonic: user.xfm Abstract: This is the main module for the base RMR user documentation. Date: 30 July 2019 Author: E. Scott Daniels .fi .dv textfont Helvetica .dv textsize 10p .gv e XFM_PASS pass .** vars picked up by front_junk or gen_title as it's a generic module .dv doc_title RIC Message Router -- RMR .dv doc_subtitle User's Guide .dv orig_date 30 July 2019 .** must reverse titles when generating rst to disambiguate in the doc list .dv reverse_titles 1 .** setup will do the right thing with the index configuration .dv toc_file user.toc .dv index_snare_file index_snatch.im .im ./setup.im .dv mtsid message type and subscription ID .dv Mtsid Message type and subscription ID .dv mt message type .dv Mt Message type .dv mts message types .** -------------------------------------------------------------------------------------- &line_len( &line_size ) &h1(Overview) The RIC Message Router (RMR) is a library for peer-to-peer communication. Applications use the library to send and receive messages where the message routing and endpoint selection is based on the message type rather than DNS host name-IP port combinations. The library provides the following major features: &half_space &indent &beg_list(&lic1) &li Routing and endpoint selection is based on &ital(message type.) &half_space &li Application is insulated from the underlying transport mechanism and/or protocols. &half_space &li Message distribution (round robin or fanout) is selectable by message type. &half_space &li Route management updates are received and processed asynchronously and without overt application involvement. &end_list &uindent &space &h2(Purpose) RMR's main purpose is to provide an application with the ability to send and receive messages to/from other peer applications with minimal effort on the application's part. To achieve this, RMR manages all endpoint information, connections, and routing information necessary to establish and maintain communication. From the application's point of view, all that is required to send a message is to allocate (via RMR) a message buffer, add the payload data, and set the message type. To receive a message, the application needs only to invoke the receive function; when a message arrives a message buffer will be returned as the function result. &h2(Message Routing) Applications are required to place a message type into a message before sending, and may optionally add a subscription ID when appropriate. The combination of message type, and subscription ID are refered to as the &ital(message key,) and is used to match an entry in a routing table which provides the possible endpoints expecting to receive messages with the matching key. &h3(Round Robin Delivery) An endpoint from RMR's perspective is an application to which RMR may establish a connection, and expect to send messages with one or more defined message keys. Each entry in the route table consists of one or more endpoint groups, called round robin groups. When a message matches a specific entry, the entry's groups are used to select the destination of the message. A message is sent once to each group, with messages being &ital(balanced) across the endpoints of a group via round robin selection. Care should be taken when defining multiple groups for a message type as there is extra overhead required and thus the overall message latency is somewhat increased. &h3(Routing Table Updates) Route table information is made available to RMR a static file (loaded once), or by updates sent from a separate route manager application. If a static table is provided, it is loaded during RMR initialization and will remain in use until an external process connects and delivers a route table update (often referred to as a dynamic update). Dynamic updates are listened for in a separate process thread and applied automatically; the application does not need to allow for, or trigger, updates. &h2(Latency And Throughput) While providing insulation from the underlying message transport mechanics, RMR must also do so in such a manner that message latency and throughput are not impacted. In general, the RMR induced overhead, incurred due to the process of selecting an endpoint for each message, is minimal and should not impact the overall latency or throughput of the application. This impact has been measured with test applications running on the same physical host and the average latency through RMR for a message was on the order of 0.02 milliseconds. &space As an application's throughput increases, it becomes easy for the application to overrun the underlying transport mechanism (e.g. NNG), consume all available TCP transmit buffers, or otherwise find itself in a situation where a send might not immediately complete. RMR offers different &ital(modes) which allow the application to manage these states based on the overall needs of the application. These modes are discussed in the &ital(Configuration) section of this document. .** snarf in the major sections (to avoid one huge source document and maybe to promote reuse) .im general_use.im .im advanced_use.im .im failures.im .im config.im .if tfm .** show all column/foot notes &h1(Notes) .cn showend &mult_space( 3 ) .fi .dv qr_appendix A .pa .if "&ot" "rst" = &h1(Appendix &qr_appendix -- Quick Reference) Please refer to the RMR manual pages on the Read the Docs site &space https://docs.o-ran-sc.org/projects/o-ran-sc-ric-plt-lib-rmr/en/latest/index.html .ei .im api_qref.im .fi .dv mbuf_appendix B .pa .im mbuf.im .dv gloss_appendix C .pa .im glossary.im .dv code_appendix D .pa .im code_appendix.im .** if pfm and index was setup, include it now .if index_here .st 8p &index_here .st &textsize .fi .pa .** capture all interesting variables to be used as forward references during pass 2 .ca expand start p1var_setup.ca .** pass 1 variable settings -- do NOT commit to repo .dv qr_appendix &qr_appendix .dv mbuf_appendix &mbuf_appendix .dv gloss_appendix &gloss_appendix .dv code_appendix &code_appendix .ca end .qu glossary: context endpoint mt/sid NNG push back route table