The RIC Message Router (RMR) is a thin library which allows applications to send messages to other applications. RMR provides insulation from the actual message transport system (e.g. Nanomsg or NNG), as well as providing endpoint selection based on message type. This page serves as an anchor point for RMR related pages.
WARNING: 15 April 2020
An potential bug has been discovered in the Linux TCP stack and has the potential to affect an xAPP which is trying to connect to another xapp. The bug can be avoided by using ONLY ODD PORT NUMBERS (e.g. 43085). The bug is related to randomly selected port numbers by the connect() system call which seem to always be even values.
Announcements
The following are announcements related to RMR during the past 30 days; newest announcements first.
2020 April 20
Version 3.8.2 pushed. This applies a CRITICAL FIX to the SI95 portion of the library. A bug introduced in the 3.7.2 patch was causing RMR to fail to request a dynamic update from the Route Manager. If any 3.7 version of RMR, or 3.8.0 version, was applied it must be replaced with 3.8.2 or later to avoid route table issues.
Version 3.8.1 pushed. This change is only to push a better user guide into the RTD site and no code changes were made. Thus, there won't be a package pushed to package cloud.
2020 April 17
Version 3.8.0 pushed. This change adds a "safe connect" to the SI95 code in order to avoid the potential of a connect attempt connecting back to the same process because of the Linux connect() even port bug. This change also fixes a potential core dump in the route table collection code when debugging is enabled.
2020 April 9
Version 3.7.1 pushed. This change removes the receive buffer maximum limit when running on top of SI95.
2020 April 7
Version 3.7.0 pushed. This change renames the healthcheck support application included in the RMR runtime package to rmr_probe. The command line is the same, and for a small amount of time the old name (health_ck) will be valid.
2020 April 3
Version 3.6.5 pushed. This corrects a potential segmentation fault when evaluating the interfaces which can be used to listen for connections.
2020 March 23
Version 3.6.2 was pushed. This fixes a bug in the initialisation process when a message is reclaimed from the buffer pool. The flag values are properly initialised. This is considered an important fix and should be picked up by all applications relying on RMR.
Current Version
Release B development (master branch) version tag 3.8.2 (20 Apr 2020)
Release A frozen: 1.11.1 (Amber branch) 6 November 2019
Trial branch (r2-temp): 1.10.2 Fall 2019
For a detailed description of API changes, and their related commits, please consult the CHANGES file at the top level of the RMR repo:
https://gerrit.o-ran-sc.org/r/admin/repos/ric-plt/lib/rmr
Changes to the API will be announced via this wiki page, so it is assumed that anybody interested in being notified about API changes will place a watch on this page.
Supported Transport Mechanisms
A transport mechanism is a "mid-layer" protocol which makes use of TCP/UDP and provides features such as automatic connection reestablishment and connection acceptance. RMR was originally built using the Nanomsg transport library, and was extended to use NNG (Nanomsg next generation) as NNG provides several enhancements, and Nanomsg has been all but abandoned from a maintenance perspective. While the underlying "wire" protocol of both NNG and Nanomsg are the same, the APIs are different; RMR has supported both mechanisms by supplying two sets of libraries (librmr and librmr_nng). At this point in time, NNG is stable, and as the support for Nanomsg is reduced, thus RMR will drop support for Nanomsg. In other words, beginning with version 1.0.45 (initally announced as happening in 1.0.44, but has been pushed by one) only librmr_nng will be included. This change should not have any impact on applications using RMR as the RMR API is not changing. The only change would be that applications using librmr will need to alter their build process to change the underlying RMR library to librmr_nng.
Developer Information
The following links are generally useful for developers writing applications (xAPPs) which make use of RMR.
- Frequently Asked Questions
- User's Guide
- Message Conventions
- Prebuilt Binary Packages
- Building From Source
- Using RMR
- RMR Route Tables (includes information on routing based on MEID)
- Subscription ID
- Manual (man) Pages
External Systems
The following links are likely useful for developers which must communicate with RMR based applications (e.g. route manager applications).
RMR Development
The following pages hold information that should be useful to anybody modifying and/or testing RMR itself.
RMR Packages
Several frameworks (wrappers/bindings) are being developed which provide a more simplistic interface to the xAPP developer. Installation of the framework will likely require that the RMR runtime package be installed. RMR packages (debian and RPM) are currently published on the html site https://packagecloud.io.
The generic URL below can be used to obtain a list of available packages (current version listed at the top of this page).
https://packagecloud.io/app/o-ran-sc/staging/search?q=rmr&filter=all&filter=all&dist=
Links on these pages redirect to a generalised information HTML page; the actual wget command needed to pull the package is on the right side of these pages near the bottom.
As an example, the following can be added to a Docker file to install the RMR runtime package:
# Install RMr (runtime and dev) from debian package cached on packagecloud.io
ARG RMR_VER=3.3.0
RUN wget -nv --content-disposition https://packagecloud.io/o-ran-sc/staging/packages/debian/stretch/rmr_${RMR_VER}_amd64.deb/download.deb
RUN dpkg -i rmr_${RMR_VER}_amd64.deb
Performance
The following pages discuss RMR and NNG performance.
Support Software
When the RMR runtime package is installed, there may be one or more support binaries which are included. These are installed (by default) into /usr/local/bin. The links below describe each.
Tutorials
The following are links to short tutorials covering some aspects of RMR usage