JSON-RPC 2.0 Fundamentals

JSON-RPC 2.0 is a small protocol for representing remote procedure calls (RPC) as JSON documents. A remote procedure call simply means invoking an operation on another application or service in a similar way to calling a local method. JSON-RPC does not define the business model of the application. It only defines the envelope used to call a method and receive a result or error.

JSON-RPC 2.0 defines only a small number of standard fields used by requests and responses:

• jsonrpc - must be the string 2.0.
• method - the name of the remote method to call.
• params - optional method parameters, either by object or array.
• id - correlation value used to match response to request.
• result - operation result returned by a successful response.
• error - error information returned when request processing fails.

RPC Request Example

{
  "jsonrpc": "2.0",
  "method": "Shipment.Search",
  "params": {
        "trackingNumber": "TRK-123"
  },
  "id": "2"
}

Successful Response Example

{
  "jsonrpc": "2.0",
  "result": {
        "trackingNumber": "TRK-123",
        "status": "In Transit"
  },
  "id": "2"
}

Error Response Example

{
  "jsonrpc": "2.0",
  "error": {
        "code": -32601,
        "message": "Method not found"
  },
  "id": "2"
}

The important design lesson is separation of concerns. JSON-RPC describes how the call is packaged. Your application decides what the method names mean and what the parameter and result payloads contain (highlighted in gray color in the examples above).

Standard Versus Application-Specific Fields

Applications may introduce additional custom fields when necessary, for example for tracing, diagnostics, routing, or multi-tenant support, but those fields are often discouraged unless truly needed because:

• they reduce interoperability
• they complicate clients
• metadata is often better transported through HTTP headers instead

 

Table of Content Operation-Oriented APIs and AI Tools Previous: From REST APIs to Operation-Oriented APIs Next: Single Endpoint Architecture

 

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Business Process Programming in .Net
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