Sagittarius Users' Reference

(rpc json) - JSON RPC library

Library (rpc json)

This library provides procedures handling JSON RPC 2.0.

This library doesn't provide transport layer. To send request and receive response, use Http transport.

This library uses JSON parser library and its JSON representation.

Following piece of code describes how to use;

(import (rnrs) (rpc json) (rpc transport http))

(define (json-rpc-send&request url method param)
  (let ((request (make-json-request method :param param)))
    (let-values (((status header response) (rpc-http-request url request)))
      ;; rpc-http-request unmarshalls only when HTTP status starts with "2"
      ;; for this example we don't check it.
      (json-response-result response))))

(json-rpc-send&request "http://localhost/json-rpc" "sample" "parameter")
;; -> result of method execution

Class <json-request>

Class <json-response>

These classes represents JSON RPC request and response respectively.

The class instance should be created by make-json-request, json-string->json-request or json-string->json-response. Users should not create an instance directly using make.

Predicates

Function json-request? object

Function json-response? object

Returns #t if the given object is an instance of <json-request> and <json-response> respectively.

Constructors

Function make-json-request method :key (params '()) id

Creates a JSON RPC request.

method must be a symbol or string represents method name to be invoked.

The keyword argument params is the params field of the JSON RPC protocol.

The keyword argument id is the id field of the JSON RPC protocol. If this is not specified then a value generated by UUID v4 will be used.

Function json-string->json-request json

Function json-string->json-response json

Creates JSON RPC request and response from given JSON string json.

Accessors

Function json-request-method json-request

Function json-request-params json-request

Function json-request-id json-request

Retrieves JSON RPC request's method, params and id respectively from given json request object json-request.

Function json-response-result json-response

Function json-response-id json-response

Retrieves JSON RPC response's result and id respectively from given json response object json-response.

Converters

Function json-request->json-string json-request

Function json-response->json-string json-response

Converts given json-request and json-response to JSON string.

Implemented methods

Following methods are currently used only in (rpc http transport). When we support other transport, this implementation may change.

Message methods

Method rpc-marshall-message (message )

Converts to given JSON RPC request object to UTF8 bytes.

Method rpc-unmarshall-message (type (eql 'json)) body

Converts to given UTF8 bytes to JSON RPC response object.

Transport methods

Method rpc-http-content-type (message )

Returns application/json content type header value

Method rpc-http-response-type (message )

Returns json symbol.