JsonServices

This is a simple library for message-based services running on top of the
WebSockets or ZeroMQ connection and based on JSON-RPC 2.0 Specification:

https://www.jsonrpc.org/specification

The project consists of C# server, C# client and TypeScript client.
Note that TypeScript client supports only web socket connections.

Message-based RPC

The communication is based on message names, not service and/or method names
like normal RPC. The idea is inspired by ServiceStack architecture.

C# server code example:

// request message
public class GetUser : IReturn<GetUserResponse>
{
  public long? UserId { get; set; }
  public string UserName { get; set; }
}

// response message
public class GetUserResponse
{
  public long UserId { get; set; }
  public string UserName { get; set; }
  public string Email { get; set; }
}

// service handler
public class GetUserService: IService<GetUser>
{
  public GetUserResponse Execute(GetUser request)
  {
    if (request.UserId.HasValue)
    {
      return GetUserById(request.UserId.Value);
    }

    return GetUserByName(request.UserName);
  }
	...
}

TypeScript client code example:

// request message
public class GetUser implements IReturn<GetUserResponse> {
  public userId?: number;
  public userName?: string;

  public createResponse() {
    return new GetUserResponse();
  }
}

// response message
public class GetUserResponse {
  userId: number;
  userName: string;
  email: string;
}

// client code
const client = new JsonClient("ws://localhost:8765/");

const getUser = new GetUser();
getUser.userId = 7;

const result = await client.call(getUser);

JSON-RPC messages for the above example

Normal method execution:

→ { "jsonrpc": "2.0", "method": "GetUser", "params": { "UserID": 1 }, "id": 1 }
← { "jsonrpc": "2.0", "result": { "UserID": 1, "UserName": "root", "Email": "[email protected]" }, "id": 1 }

Server reply when the method is not found:

← { "jsonrpc": "2.0", "error": { "code": -32601, "message": "Method not found"}, "id": "1" }

Event subscription (one-way call):

→ { "jsonrpc": "2.0", "method": "rpc.subscribe", "params": [ "FeedUpdated", "MessageSent" ] }

Event unsubscription (one-way call):

→ { "jsonrpc": "2.0", "method": "rpc.unsubscribe", "params": [ "MessageSent" ] }

Server-side notification:

← { "jsonrpc": "2.0", "method": "MessageSent", params: { "text": "Hello world!" } }

Transport-specific notes

WebSockets (via WebSocketSharp)

• Implements both client and server
• Supports both IP addresses and host names, i.e. ws://localhost:8765
• .NET 4.5 only
• Chrome browser's WebSocket implementation connects to WebSocketSharp server
• Node.js ws module seem to have troubles connecting to WebSocketSharp server

WebSockets (via Fleck)

• Implements only server (WebSocketSharp client can connect to Flex server)
• Supports only IP addresses, i.e. ws://127.0.0.1:8765
• .NET 4.5 and .NET Standard 2.0
• Chrome browser's WebSocket implementation connects to Fleck server
• Node.js ws module also connects to Fleck server

ZeroMQ (via NetMQ)

• Implements both client and server
• Supports only tcp protocol
• .NET 4.5 and .NET Standard 2.0
• Browsers are unable to connect to ZeroMQ endpoints
• Node.js in theory should be able to connect using zeromq.js npm (not tested)

SDK versioning

The project uses Nerdbank.GitVersioning tool to manage versions.
Each library build can be traced back to the original git commit.

Preparing and publishing a new release

1. Make sure that nbgv dotnet CLI tool is installed and is up to date
2. Run nbgv prepare-release to create a stable branch for the upcoming release, i.e. release/v1.0
3. Switch to the release branch: git checkout release/v1.0
4. Execute unit tests, update the README, etc. Commit and push your changes.
5. Run dotnet pack -c Release and check that it builds Nuget packages with the right version number.
6. Run nbgv tag release/v1.0 to tag the last commit on the release branch with your current version number, i.e. v1.0.7.
7. Push tags as suggested by nbgv tool: git push origin v1.0.7
8. Go to github project page and create a release out of the last tag v1.0.7.
9. Verify that github workflow for publishing the nuget package has completed.