openmodule 9.0.0rc19

Libraries for developing the arivo openmodule

OpenModule V2

Some additional documentation:

• Openmodule Core
• RPC Server / Client

Changes

Breaking changes are annotated here.

To quickly check if your service is susceptible to a known issue have a look here.

Coding Standard

For ARIVO developers we have defined a simple coding standard here

Features

The openmodule package provides a lot of features:

Settings

The openmodule package uses a global lazy configuration openmodule.config.settings. This setting includes some standard parameters defined in openmodule.config.GlobalSettings and parameters from a customizable module. To specify the module you can call settings.configure(module) or you can set the environment variable SETTINGS_MODULE. Per default settings looks for the config module (it also looks for the tests/config module first for test cases)

Models

Inherit from OpenModuleModel or in case of ZMQ messages from ZMQMessage. Models use pydantic (docs), check openmodule.models.* for some examples (e.g. PresenceBaseMessage for alias)

Core

The base of the new openmodule, every package should have exactly one. The core handles various things:

• sentry
• logging
• dsvgo
• messaging
• health
• alerting
• database

core = init_openmodule(config, **kwargs)
shutdown_openmodule()

Messaging

Receiving messages

The core handles message distribution with a dispatcher. You only need to register your callback.

• register_schema: Automatically create a schema for your message handler and its models -> Beware that you need to document your handler method

core.messages.register_handler(b"topic", MessageClass, callback, filter={type = "demo"}, register_schema = True)

It may also be used together with an event listener to provide further functionality

event_listener = EventListener(log=logger)
core.messages.register_handler(b"topic", MessageClass, event_listener, filter={type = "demo"})
...
event_listener.append(some_function)

Sending messages

It is even easier to send messages

message = ZMQMessage(name=core.config.NAME, type="demo")
core.publish(message, b"topic")

Health

Due to the new convention, the health message should only represent if the service is still alive. This is done automatically by the core. If you need to specify some meta data or errors you can pass your handler to the core or set it later

def healthy() -> HealthResult:
    if error:
        return health_error("we have an error", meta=dict(error="error"))
    return health_ok(meta=dict(this="is_easy"))


core = init_openmodule(config, health_handler=healthy)
# or
core.health.health_hanlder = healthy

Alerting

The new core also includes an alert handler.

core.alerts.send(...)
alert_id = core.alerts.get_or_add_alert_id(...)
core.alerts.send_with_alert_id(alert_id, ...)

Database

The openmodule package now also feature a simple database which can be also specified during the template creation. If you missed it there, just copy the directory src/database from the template. For more infos see here

RPCs

A new RPC server/client was implemented. It works like before and also includes better filtering:

• if a channel is provided for a filter, only rpcs of that channel will be subject to that filter
• if a type is provided for a filter, only rpcs of that type will be subject to that filter
• register_schema: Automatically create a schema for your rpc and its models -> Beware that you need to document your handler method

def handler(request: AccessRequest):
    """
    awesome description
    """


rpc = RPCServer(config=core.config, context=core.context)
rpc_server.add_filter(self._backend_filter, "backend", "auth")
rpc_server.register_handler("backend", "auth", request_class=AccessRequest,
                            response_class=AccessResponse, handler=handler, register_schema=True)
rpc.run()

Utils

Api

We implemented a very basic Api class you can use for http request and that handles errors and authentication. Either inherit it or create a class.

api = Api(**kwargs)
try:
    res = api.post("some_url", payload=stuff)
except ApiException as e:
    if e.retry:  # <- makes sense to try again - timeouts or server not available ...
        ...

Backend

There is also a basic implementation of a backend that provides registration and message passing.

class MyBackend(Backend):
    def check_access(self, request: AccessRequest) -> List[Access]:
        ...

    def check_in(self, message: CountMessage):
        ...

    def check_out(self, message: CountMessage):
        ...

Charset

Useful functions for character manipulation

Connection Status

Helper class that checks the connection status of ogclient to our server:

connection_status = ConnectionStatusListener(core.messages)
connection_status.on_connect.append(some_function)
connection_status.on_disconnect.append(some_function)

Matching

Useful functions for license plate matching

Presence

Helper class for listening to presence messages.

presence_listener = PresenceListener(core.messages)
presence_listener.on_enter.append(some_function)

Documentation

Openmodule >= 3.0.5 features automatic generation of Rpc and Message Schemas including their models. The generation uses data that is generated during the test runs to create an OpenApi Schema. Your RPCs and Message handlers are automatically documented if:

• You use the message dispatcher of the core (OpenModuleCoreTestMixin)
• You use the RPCServer of Openmodule

You can also register models yourself if you want them documented, but you may need to save the Schema in this case:

from openmodule.utils.schema import Schema

Schema.save_model(Model)
Schema.save_rpc(channel, type, request, reqponse, handler)
Schema.save_message(topic, message_class, handler, filter)

Schema.to_file()

With default parameters, you need to document your handler functions with a doc string, that is then included as a description.

Testing

A separate package for testing openmodule packages exists within openmodule - openmodule-test. For more infos see here