SHERPA Communication Mediator

This folder contains the SHERPA Proxy implementation.

Dependencies

• C libraries and gcc compiler
• zmq: https://github.com/zeromq/libzmq
• czmq: https://github.com/zeromq/czmq
• zyre: https://github.com/zeromq/zyre
• jansson JSON library: https://jansson.readthedocs.org/en/latest/gettingstarted.html

For more information see the Dependencies file.

Installation

• clone the project and move into this directory:

git clone https://github.com/maccradar/sherpa-com-mediator.git
cd sherpa-com-mediator

• Build the project

~/sherpa-com-mediator$ make
~/sherpa-com-mediator$ mkdir build
~/sherpa-com-mediator$ cd build
~/sherpa-com-mediator/build$ cmake ..
~/sherpa-com-mediator/build$ make
~/sherpa-com-mediator/build$ cd ..

• Open start the mediator and provide it with a config file

~/sherpa-com-mediator/$ ./bin/sherpa_comm_mediator examples/configs/donkey.json

Examples:

Find examples and their explanation in the corresponding subfolders. There is an example for each, C and Python code. The C example shows how to query for a list of connected robots and their configuration. The Python example still needs to be done :-)

Example 1: Query for list of connected nodes

In this exaple we launch several instances of mediators (i.e. robots). Then we start a local component that queries for a list of all available robots. It will send the query and then wait for the reply, print the list of robots with their header/configuration data and exit.

Build the example

Run the makefile in the folder.

Run the example

Open three terminals. Start the mediator of the first agent that will connect to our local compoenent in the first terminal.

~/sherpa-com-mediator/$ ./bin/sherpa_comm_mediator examples/configs/donkey.json

Start a second agent in the second terminal.

~/sherpa-com-mediator/$ ./bin/sherpa_comm_mediator examples/configs/wasp1.json

Start the local component that will query for the peer list in the third terminal.

~/sherpa-com-mediator/$ cd examples/request_peers/
~/sherpa-com-mediator/examples/request_peers/$ ./request_peers_example

For code explanations see the comments in the code. If specific questions remain, ask the authors.

Example 2: Send message and handle replies

Build the example

Run the makefile in the folder.

Run the example

Open three terminals. Start the mediator of the first agent that will connect to our local compoenent in the first terminal.

~/sherpa-proxy/$ ./bin/sherpa_comm_mediator examples/configs/donkey.json

Start a second agent in the second terminal.

~/sherpa-proxy/$ ./bin/sherpa_comm_mediator examples/configs/wasp1.json

Start the local component in the third terminal.

~/sherpa-proxy/$ cd examples/messaging/
~/sherpa-proxy/examples/request_peers/$ ./messaging_example

For code explanations see the comments in the code. If specific questions remain, ask the authors.

Missing features:

• Subscribe to network changes (e.g. node becomes (un-)available) -> if somebody needs that, please contact us

TODOs:

• Refactor example code
• Make features composable
• Port gossip protocol to pyre and provide python example