Distributed Minimalistic SRTC System¶

The provided Putting Everything Together for a Minimalistic SRTC System example can run as it is just on a single machine. This tutorial will explain how what changes are needed to run the example on multiple distributed machines. In particular running the example on two machines.

The example is based on the Putting Everything Together for a Minimalistic SRTC System example, and this tutorial concentrates only on the parts that need to be modified.

Prerequisites¶

Two network connected machines with same ELT Development Environment installation.
As Service Discovery/deployment is in this version of RTC toolkit based on the file system we need to share these information between the machines. The easiest way to do this is to share the INTROOT area using a distributed file system like NFS.
In addition the DDS (multicast) communication between the machines has to be configured correctly
ssh is installed and setup so that is possible to remotely execute commands without entering the password.

Setup¶

The example needs two machines to run:

Node	Description
Simple SRTC	Machine where supervisor, telemetry subscriber and data task run.
Simple HRTC Gateway	Machine where telemetry republishing and MUDPI source run.

The Example Components and deployment¶

The same components as in the Putting Everything Together for a Minimalistic SRTC System case are used:

On Simple HRTC gateway node run:

Executable	Instance (component) name
rtctkMudpiPublisher
rtctkTelRepub	tel_repub_1

On Simple SRTC node run:

Executable	Instance (component) name
rtctkExampleTelSub	tel_sub_1
rtctkExampleDataTask	data_task_1
rtctkRtcSupervisor	rtc_sup

Modifications¶

The baseline Putting Everything Together for a Minimalistic SRTC System code example for modification can be found in:

_examples/exampleEndToEnd

To run the system distributed over two nodes we need to change the configuration and the script used to run the example.

Configuration¶

Let’s assume that the two machines have the following IP addresses:

Node	IP
Simple SRTC	134.171.2.88
Simple HRTC Gateway	134.171.2.78

Depending on which machines particular component are run we need to set proper IP addresses for:

req_rep_endpoint

pub_sub_endpoint

in config/resource/config/rtctk/rtctkRefImpl/service_disc.yaml as follow:

common:

    ...

rtc_sup:
    req_rep_endpoint:
        type: RtcString
        value: zpb.rr://134.171.2.88:12081/
    pub_sub_endpoint:
        type: RtcString
        value: zpb.ps://134.171.2.88:12082/
tel_repub_1:
    req_rep_endpoint:
        type: RtcString
        value: zpb.rr://134.171.2.78:12083/
    pub_sub_endpoint:
        type: RtcString
        value: zpb.ps://134.171.2.78:12084/
tel_sub_1:
    req_rep_endpoint:
        type: RtcString
        value: zpb.rr://134.171.2.88:12085/
    pub_sub_endpoint:
        type: RtcString
        value: zpb.ps://134.171.2.88:12086/
data_task_1:
    req_rep_endpoint:
        type: RtcString
        value: zpb.rr://134.171.2.88:12087/
    pub_sub_endpoint:
        type: RtcString
        value: zpb.ps://134.171.2.88:12088/

Script¶

The script rtctkExampleEndToEnd.sh located in : scripts/src/rtctkRefImpl.sh which among other things starts the executables has to be be run on the Simple SRTC node, but before it is run some modifications are needed.

Parts where telemetry republisher is started/stopped using ssh to remotely execute/stop the processes.

function do_start () {
    ...
    ssh 134.171.2.78 rtctkTelRepub tel_repub_1 "$SVC_DISC_ENDPOINT" &> rtctkTelRepub.tel_repub_1.log &
    ...

function do_stop () {
    ...
    ssh 134.171.2.78 killall rtctkTelRepub
    ...

Parts where MUDPI publisher is started/stopped using ssh to remotely execute/stop the processes.

function do_start_data () {
    ...
    ssh 134.171.2.78 rtctkMudpiPublisher -d "$DELAY" -s 36928 localhost "$PORT" "$TOPIC" &> rtctkMudpiPublisher.log  &
   ...

function do_stop () {
    ...
    ssh 134.171.2.78 killall --quiet --wait -SIGTERM rtctkMudpiPublisher
    .....

Running the Example¶

After the modification and installation (waf install) the example should be run on machine Simple SRTC as Putting Everything Together for a Minimalistic SRTC System example. The output of telemetry republisher and MUDPI publisher can be retrieved from rtctkTelRepub.tel_repub_1.log and rtctkMudpiPublisher.log respectively.