JSON-RPC: Difference between revisions

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{{Short description|JSON-based wire protocol for remote procedure calls}}

'''JSON-RPC''' ('''JavaScript Object Notation-Remote Procedure Call''') is a [[remote procedure callJSON]]-based [[Protocolwire (computing)|protocol]] encoded infor [[JSONremote procedure call]]s (RPC). It is similar to the [[XML-RPC]] protocol, defining only a few data types and commands. JSON-RPC allows for notifications (data sent to the server that does not require a response) and for multiple calls to be sent to the server which may be answered asynchronously.

The JSON-RPC protocol is transport-independent and can be carried over many different data transport protocols, including [[file descriptor]] I/O, [[HTTP]] and [[TCP]]. It does not directly provide any support for authentication or authorization.

== History ==

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|-

| 1.0

| [https://webwww.archivejsonrpc.org/web/20080517011921/http://json-rpc.org/wiki/specificationspecification_v1 Original version]

| 2005

|-

| 1.1 WD

| [https://web.archivejsonrpc.org/web/20100718181845/http:/historical/json-rpc.org/wd/JSON-RPC-1-1-WD-20060807wd.html Working draft]. Adds named parameters, adds specific error codes, and adds introspection functions.

| 2006-08-07

|-

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JSON-RPC works by sending a request to a server implementing this protocol. The client in that case is typically software intending to call a single method of a remote system. Multiple input parameters can be passed to the remote method as an array or object, whereas the method itself can return multiple output data as well. (This depends on the implemented version.)

All transfer types are single objects, serialized using JSON.<ref name="json-rpc1">{{Cite web |url=http://json-rpc.org/wiki/specification |title=specification - JSON-RPC - Trac<!-- Bot generated title --> |access-date=2008-05-14 |archive-url=https://web.archive.org/web/20080517011921/http://json-rpc.org/wiki/specification |archive-date=2008-05-17 |url-status=dead }}</ref> A request is a call to a specific method provided by a remote system. It mustcan contain three certain propertiesmembers:

* <code>method</code> - A Stringstring with the name of the method to be invoked. Method names that begin with "rpc." are reserved for rpc-internal methods.

* <code>params</code> - An Objectobject or Arrayarray of values to be passed as parameters to the defined method. This member may be omitted.

* <code>id</code> - A string or non-fractional number used to match the response with the request that it is replying to.<ref>{{cite web|url=https://www.jsonrpc.org/specification|title=JSON-RPC 2.0 Specification|quote=id: An identifier established by the Client that MUST contain a String, Number, or NULL value if included. If it is not included it is assumed to be a notification. The value SHOULD normally not be Null and Numbers SHOULD NOT contain fractional parts}}</ref> This member may be omitted if no response should be returned.<ref>{{cite web|url=https://www.jsonrpc.org/specification|title=JSON-RPC 2.0 Specification|quote=A Notification is a Request object without an "id" member. A Request object that is a Notification signifies the Client's lack of interest in the corresponding Response object, and as such no Response object needs to be returned to the client. The Server MUST NOT reply to a Notification, including those that are within a batch request. Notifications are not confirmable by definition, since they do not have a Response object to be returned. As such, the Client would not be aware of any errors (like e.g. "Invalid params", "Internal error").}}</ref>

The receiver of the request must reply with a valid response to all received requests. A response mustcan contain the propertiesmembers mentioned below.

* <code>result</code> - The data returned by the invoked method. This element is formatted as a JSON-stat object. If an error occurred while invoking the method, this member must not exist.<ref>{{cite web|url=https://www.jsonrpc.org/specification|title=JSON-RPC 2.0 Specification|quote=result: This member is REQUIRED on success. This member MUST NOT exist if there was an error invoking the method. The value of this member is determined by the method invoked on the Server.

}}</ref>

* <code>error</code> - A specified error code if there was an error invoking the method, otherwise this member must not exist.<ref>{{cite web|url=https://www.jsonrpc.org/specification|title=JSON-RPC 2.0 Specification|quote=error: This member is REQUIRED on error. This member MUST NOT exist if there was no error triggered during invocation. The value for this member MUST be an Object as defined in section 5.1.

}}</ref>

* <code>error</code> - A specifiedAn error codeobject if there was an error invoking the method, otherwise this member must not exist.<ref>{{cite web|url=https://www.jsonrpc.org/specification|title=JSON-RPC 2.0 Specification|quote=error: This member is REQUIRED on error. This member MUST NOT exist if there was no error triggered during invocation. The value for this member MUST be an Object as defined in section 5.1.

}}</ref> The object must contain members ''code'' (integer) and ''message'' (string).<ref>{{cite web|url=https://www.jsonrpc.org/specification|title=JSON-RPC 2.0 Specification|quote=Error object: When a rpc call encounters an error, the Response Object MUST contain the error member with a value that is a Object with the following members: (code) - A Number that indicates the error type that occurred. This MUST be an integer. (message) - A String providing a short description of the error. The message SHOULD be limited to a concise single sentence. (data) - A Primitive or Structured value that contains additional information about the error. This may be omitted. The value of this member is defined by the Server (e.g. detailed error information, nested errors etc.).}}</ref> An optional ''data'' member can contain further server-specific data. There are pre-defined error codes which follow those defined for XML-RPC.

* <code>id</code> - The id of the request it is responding to.

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=== Version 2.0 ===

Request and response:

<syntaxhighlight lang="javascriptjson">

--> {"jsonrpc": "2.0", "method": "subtract", "params": {"minuend": 42, "subtrahend": 23}, "id": 3}

<-- {"jsonrpc": "2.0", "result": 19, "id": 3}

</syntaxhighlight>

Notification (no response):

<syntaxhighlight lang="javascriptjson">

--> {"jsonrpc": "2.0", "method": "update", "params": [1,2,3,4,5]}

</syntaxhighlight>

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=== Version 1.1 (Working Draft) ===

Request and response:

<syntaxhighlight lang="javascriptjson">

--> {"version": "1.1", "method": "confirmFruitPurchase", "params": [["apple", "orange", "mangoes"], 1.123], "id": "194521489"}

<-- {"version": "1.1", "result": "done", "error": null, "id": "194521489"}

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=== Version 1.0 ===

Request and response:

<syntaxhighlight lang="javascriptjson">

--> {"method": "echo", "params": ["Hello JSON-RPC"], "id": 1}

<-- {"result": "Hello JSON-RPC", "error": null, "id": 1}

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== See also ==

* [[gRPC]] - cross-platform binary RPC protocol

* [[Remote procedure call]] (RPC)

* [[SOAP]] - a messaging protocol

* [[XML-RPC]]

* [[JSON-WSP]] - a JSON-RPC inspired protocol with a service description specification.

* [[gRPC]]

* [[SOAPjr]] - a hybrid of SOAP and JSON-RPC

* [[JSON-WSP]] - a JSON-RPC inspired protocol with a service description specification.

* [https://github.com/omniti-labs/jsend JSend] - a similar specification which defines only format of response

== References ==

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* [http://www.simple-is-better.org/json-rpc/transport_http.html HTTP transport] description for JSON-RPC-2

* [https://open-rpc.org OpenRPC Specification] Service description format for JSON-RPC. (open-api, but for json rpc)

* [https://github.com/omniti-labs/jsend JSend] - a similar specification which defines only format of response

{{DEFAULTSORT:Json-Rpc}}