doc/src/man/rmr.7.xfm

.if false
==================================================================================
	Copyright (c) 2019 Nokia
	Copyright (c) 2018-2019 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	rmr.7.xfm
	Abstract	The manual page for the whole RMr library
	Author		E. Scott Daniels
	Date		29 January 2019
.fi

.** if formatting with tfm, the roff.im will cause roff output to be generated
.** and rst.im will cause rst to be generated depending on OUTPUT_TYPE env
.** var.
.** if formatting with pfm, then pretty postscript will be generated

.gv e LIB lib
.if pfm
	.im &{lib}/generic_ps.im
.ei
	.gv e OUTPUT_RST use_rst
	.if .ev &use_rst 1 =
		.im &{lib}/rst.im
	.ei
		.im &{lib}/roff.im
	.fi
.fi

&line_len(6i)

&h1(RMr Library)
&h2(NAME)
	RMr -- Ric Message Router Library

&h2(DESCRIPTION)
RMr is a library which provides  a user application with the ability
to send and receive messages to/from  other RMr based applications
without having to understand the underlying messaging transport environment (e.g. Nanomsg)
and without needing to know which other endpoint applications are currently
available and accepting messages.
To do this, RMr depends on a routing table generated by an external source.
This table is used to determine the destination endpoint of each message sent by mapping the
message type T (supplied by the user application) to an endpoint entry.
Once determined, the message is sent directly to the endpoint.
The user application is unaware of which endpoint actually receives the
message, and in some cases whether that message was sent to multiple
applications.

&space
RMr functions do provide for the ability to respond to the specific source
instance of a message allowing for either a request response, or call
response relationship when needed. 


&h3(The Route Table)
The library is supplied with a route table which maps message numbers to
endpoint groups such that each time a message of type T is sent, the message
is delivered to one member of each group associated with T.
For example, message type 2 might route to two different groups where
group A consists of worker1 and worker2, while group B consists only of
logger1.

&space
It is the responsibility of the route table generator to know which endpoints
belong to which groups, and which groups accept which message types.
Once understood, the route table generator publishes a table that is ingested
by RMr and used for mapping messages to end points.

&h3(Environment)
To enable configuration of the library behaviour outside of direct user application
control, RMr supports a number of environment variables which provide information
to the library. 
The following is a list of the various environment variables, what they control
and the defaults which RMr uses if undefined.

&beg_dlist(.75i : ^&bold_font )
&di(RMR_BIND_IF) This provides the interface that RMr will bind listen ports to allowing
	for a single interface to be used rather than listening across all interfaces.
	This should be the IP address assigned to the interface that RMr should listen
	on, and if not defined RMr will listen on all interfaces.

&di(RMR_RTG_SVC) RMr opens a TCP listen socket using the port defined by this
	environment variable and expects that the route table generator process
	will connect to this port.
	If not supplied the port 4561 is used.

&di(RMR_RTG_ISRAW) Is set to 1 if the route table generator is sending "plain" messages
	(not using RMr to send messages, 0 if the rtg is using RMr to send. The default
	is 1 as we don't expect the rtg to use RMr.

&di(RMR_SEED_RT) This is used to supply a static route table which can be used for
	debugging, testing, or if no route table generator process is being used to
	supply the route table. 
	If not defined, no static table is used and RMr will not report &ital(ready)
	until a table is received.
&end_dlist


&h2(SEE ALSO )
.ju off
rmr_alloc_msg(3),
rmr_tralloc_msg(3),
rmr_call(3),
rmr_free_msg(3),
rmr_init(3),
rmr_init_trace(3),
rmr_get_src(3),
rmr_get_srcip(3),
rmr_get_trace(3),
rmr_get_trlen(3),
rmr_payload_size(3),
rmr_rcv_msg(3),
rmr_rcv_specific(3),
rmr_rts_msg(3),
rmr_ready(3),
rmr_fib(3),
rmr_has_str(3),
rmr_tokenise(3),
rmr_mk_ring(3),
rmr_ring_free(3),
rmr_set_trace(3),
rmr_torcv_msg(3),
rmr_wh_open(3),
rmr_wh_send_msg(3)
.ju on


.qu