Coordinate is a standalone server process and client library for multiple-system coordination and synchronization capabilities. It manages work specifications and work units, weighted scheduling, priority scheduling, and dependency graph.
In a global yakonfig config.yaml configuration file, add coordinate at the top level:
coordinate:
server:
host: 0.0.0.0
port: 5932
namespace: *namespace
registry_addresses: ['10.0.1.x:5932']
Run coordinated with this configuration, or manually specify --host and --port. The default configuration is to only listen on the localhost interface on port 5932.
The main interface is through the TaskMaster object. This implementation makes RPC calls to the coordinated server.
The server is pluggable and additional functionality can be through other server objects similar to the JobQueue class.
Coordinated uses a simple RPC system based on CBOR messages. Client processes initiate a TCP connection as indicated in the configuration and send CBOR messages like (JSON syntax):
{"id": 1,
"method": "lock",
"params": [...]}
where id is a sequential number per client object, starting at 1. There is one TCP connection per client object, but this connection is held open until explicitly closed.
The responses look like:
{"id": 1,
"result": "value"}
Or:
{"id": 2,
"error": {"message": "No such method"}}
If the server-side call raised an exception, the formatted traceback is included as the error message.
The server supports a CBOR list of request messages, and will return a CBOR list of responses.
Client classes subclass coordinated._cbor_rpc_client.CborRpcClient and call _rpc() to perform a call. This method blocks on the connection and response. If the server returned the error form, this is raised as an exception.
The server is run with a proxy object, presently coordinated.lockd.MultiBackendProxyObject, and calls the requested methods on that object with the requested parameters.