en workshop impl platform adapter

Implementing a Message Platform Adapter

This article will use the aiocqhttp adapter as an example to explain how to implement a new message platform adapter for LangBot, in order to integrate new message platform protocols such as WhatsApp and Discord.

Registration

Add a new message platform adapter, for example: integrate WhatsApp, Discord, etc.

- Base class: `pkg.platform.adapter.MessageSourceAdapter`
- Decorator: `pkg.platform.adapter.adapter_class(name: str)`
- Reference implementation: `pkg.platform.sources/`

To implement a message platform adapter, we essentially need to implement a class that inherits from the base class and register it using the decorator. Finally, it will be available for users to select and use during runtime.

Contributing to the Main Repository

Create a new file aiocqhttp.py in the pkg/platform/sources/ directory:

from .. import adapter

@adapter.adapter_class("aiocqhttp")
class AiocqhttpAdapter(adapter.MessageSourceAdapter):
    pass

Also import this module in pkg/platform/manager.py at line 40:

        from .sources import nakuru, aiocqhttp, qqbotpy

Finally, write your own manifest file by referring to other adapters' manifest files.

Event and Message Converters

The main work of a message platform adapter is to receive events from the message platform protocol, convert them into LangBot's format, pass them to the core components, and after LangBot's core components process them, pass the content that needs to be replied to the message platform adapter, which then converts the content into the platform protocol format and sends it to the message platform.

The following diagram shows the processing patterns for two scenarios: message platform protocol without SDK and with mature SDK. In the first case, we need to implement connection management and network format data conversion to LB message Python objects according to the message platform protocol documentation. In the second case, the message platform has a mature SDK, we only need to create connections according to the SDK documentation, register event listeners, and implement message converters.

In the pkg.platform.sources.aiocqhttp file, we can see not only AiocqhttpAdapter, but also class AiocqhttpMessageConverter(adapter.MessageConverter): and class AiocqhttpEventConverter(adapter.EventConverter):.

• MessageConverter is used for converting between LangBot messages and platform messages.
• EventConverter is used for converting between LangBot events and platform events.

TBC...