GSOC : Add JSON serialization support for Python Dubbo

[aditya0yadav]

What is the purpose of the change

ISSUE: #issue_number

Brief changelog

Verifying this change

Checklist

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[aditya0yadav]

Hi @cnzakii,
Aditya here 👋

This is an exemplary pull request to demonstrate JSON serialization support in the Python Dubbo framework.

Purpose

The goal of this PR is to add JSON serialization capabilities using Pydantic, by building a modular structure around DubboCodec and the codec registry. This helps streamline how JSON is handled and decoded between services in a clean and extensible manner.

Highlights

• Introduced modular codec handling using DubboCodec
• JSON serialization with Pydantic models for both request and response

Example

Client:

self.unary = client.unary(
    method_name="unary",
    codec_type="json",
    request_model=UserListResponse,
    response_model=UserRequest
)

Server:

method_handler = RpcMethodHandler.unary(
    UserServiceHandler().list_users,
    method_name="unary",
    codec_type="json",
    request_model=UserRequest,
    response_model=UserListResponse
)

Notes

• Variable naming has been done thoughtfully, but open to suggestions if any part feels unclear.
• Please review and let me know if any adjustments are needed.
• I can also provide the full client/server examples if required.

Thanks for reviewing this! Let me know your thoughts.

[cnzakii]

@aditya0yadav
Hi, I'll review the code as soon as possible.
In addition, to improve communication efficiency, it would be better to use an instant messaging tool since email can be a bit slow.
Do you use DingTalk, WeChat, or any other messaging app? Or is there a communication tool you prefer?

[aditya0yadav]

@cnzakii
Sorry, I forgot to add the license header in the file
I just added that

[aditya0yadav]

@cnzakii @AlbumenJ Just wanted to check — is the design suitable for JSON serialization? If yes, I’ll go ahead and start working on Protobuf

[cnzakii]

@aditya0yadav

Code Review Report and Suggestions

1. All .DS_Store files should be excluded from the repository (e.g., via .gitignore).
2. The current CodecRegistry implementation should be replaced with Dubbo's ExtensionLoader mechanism to ensure that all extensions are centrally managed and follow a unified strategy.
3. Dependencies on libraries such as orjson and pydantic should be made optional. These modules should be structured as optional extensions, only imported when explicitly enabled by the user.
4. The current implementation of JsonCodec lacks generality. At a minimum, it should support Python’s basic data types as well as dataclass and namedtuple.
5. Although the JsonCodec class supports serializing multiple types, it only supports deserializing from bytes into a single type. This design is arguably suboptimal, as it forces users to implement a separate CustomJsonCodec for each type. This goes against the principle of ease-of-use and reusability.

Due to the limited amount of code submitted, the review is brief but focused. I hope these suggestions are helpful to your development process.

[aditya0yadav]

@cnzakii Thanks for the suggestion.
I will use the suggested approach and re-PR after checking thoroughly.