Pascal JSON-RPC lite 2

Parse and Serialize JSON-RPC2 messages in free-pascal or Delphi application. Git Repository: https://github.com/r3code/pascal-jsonrpc-lite-2

This is an enhanced version of https://github.com/r3code/pascal-jsonrpc-lite

Inspired by https://github.com/teambition/jsonrpc-lite.

An implementation of JSON-RPC 2.0 specifications

Dependencies

SuperObject JSON parsing library https://github.com/hgourvest/superobject

Install

1. Download.
2. Extract.
3. Add ujsonrpc2.pas to your project or add path to ujsonrpc2.pas to Lib Path.

uses ujsonrpc2;

API

Interface: IJsonRpcMessage

Method: IJsonRpcMessage.AsJsonObject

Returns object as ISuperObject.

Method: IJsonRpcMessage.AsJSon(indent: boolean = false; escape: boolean = true): string;

Returns a JSON string object representation.

Params:

• indent: {boolean} indent resulting JSON
• escape: {boolean} escape special chars

Class: TJsonRpcMessage

Class Method: TJsonRpcMessage.Request(id, method, params)

Creates a JSON-RPC 2.0 request object, return IJsonRpcMessage object. Realizes IJsonRpcMessage. Returns {IJsonRpcError}.

Params:

• id: {String}
• method: {String}
• params: {ISuperObject}

Example:

var requestObj: TJsonRpcMessage; 
requestObj := TJsonRpcMessage.Request('123', 'update', SO('{list: [1, 2, 3]}'));
writeln(requestObj.asString);
// {
//   jsonrpc: '2.0',
//   id: '123',
//   method: 'update',
//   params: {list: [1, 2, 3]}
// }

Class Method: TJsonRpcMessage.Notification(method, params)

Creates a JSON-RPC 2.0 notification object, returns {IJsonRpcMessage}.

Params:

• method: {String}
• params: {ISuperObject}

Example:

var notificationObj: TJsonRpcMessage;
notificationObj := TJsonRpcMessage.notification('update', SO('{list: [1, 2, 3]}'));
writeln(notificationObj.asString);
// {
//   jsonrpc: '2.0',
//   method: 'update',
//   params: {list: [1, 2, 3]}
// }

Class Method: TJsonRpcMessage.Success(id, result)

Creates a JSON-RPC 2.0 success response object, returns {IJsonRpcMessage}.

Params:

• id: {String}
• result: {ISuperObject}

Example:

var msg: TJsonRpcMessage;
msg := TJsonRpcMessage.success('123', 'OK');
writeln(msg.asString);
// {
//   jsonrpc: '2.0',
//   id: '123',
//   result: 'OK',
// }

Class Method: TJsonRpcMessage.Error(id, error)

Creates a JSON-RPC 2.0 error response object, returns {IJsonRpcMessage}.

Params:

• id: {String}
• error: {IJsonRpcError} use TJsonRpcError or it's siblings

Example:

var msg: TJsonRpcMessage;
msg := TJsonRpcMessage.Error('123', TJsonRpcError.Create(-32000, 'some error', 'blabla'));
writeln(msg.asString);
// {
//   jsonrpc: '2.0',
//   id: '123',
//   error: {code: -32000, 'message': 'some error', data: 'blabla'},
// }

Class Method: TJsonRpcMessage.Parse(s, err)

Takes a JSON-RPC 2.0 payload (string) and tries to parse it into a JSON. If successful, determine what object is it (response, notification, success, error, or invalid), and return it's type and properly formatted object. In case of error see details in err value.

Params:

• s: {String}
• err: {IJsonRpcError}

Returns one of {IJsonRpcParsedMessage} realizations if OK, else nil and err set to one of {IJsonRpcError} realizations (e.g. TJsonRpcError).

Enum: TJsonRpcObjectType

Shows the type of message detected during Parse. Types: jotInvalid, jotRequest, jotNotification, jotSuccess, jotError.

Interface: IJsonRpcParsedMessage

Method: IJsonRpcParsedMessage.GetMessageType

Returns one of {TJsonRpcObjectType}.

Method: IJsonRpcParsedMessage.GetMessagePayload

Returns stored ref to {IJsonRpcMessage}.

Class: TJsonRpcParsedMessage

Realizes interface {IJsonRpcParsedMessage}.

Constructor: TJsonRpcParsedMessage.Create(objType, payload)

Create an instance.

Params:

• objType: {TJsonRpcObjectType} message format type
• payload: {IJsonRpcMessage} message body

Interface: IJsonRpcError

Method: IJsonRpcError.GetCode

Returns error code as {Integer}.

Method: IJsonRpcError.GetMessage

Returns error message as {String}.

Method: IJsonRpcError.GetData

Returns error Data as {ISuperObject}.

Method: IJsonRpcError.AsJsonObject

Returns object as {ISuperObject}.

Class: TJsonRpcError

Describes JSON-RPC 2.0 Error object. Realizes interface {IJsonRpcMessage}.

Constructor: TJsonRpcError.Create(code,message[,data])

Creates an instance.

Params:

• code: {Integer}
• message: {String}
• data: {ISuperObject} optional

Examples:

var error: TJsonRpcError;
error =  TJsonRpcError.Create(-32651, 'some error', 'some data');

or

var error: TJsonRpcError;
error =  TJsonRpcError.Create(-32651, 'some error', SO('{ a: 1, extra: "some data"}'));

Class Method: TJsonRpcError.InvalidRequest(data)

Create {TJsonRpcError} object with error code -32600.

Params:

• data: {ISuperObject|nil} - extra data

Class Method: TJsonRpcError.MethodNotFound(data)

Create {TJsonRpcError} object with error code -32601.

Params:

• data: {ISuperObject|nil} - extra data

Class Method: TJsonRpcError.InvalidParams(data)

Create {TJsonRpcError} object with error code -32602.

Params:

• data: {ISuperObject|nil} - extra data

Class Method: TJsonRpcError.InternalError(data)

Create {TJsonRpcError} object with error code -32603.

Params:

• data: {ISuperObject|nil} - extra data

Class Method: TJsonRpcError.ParseError(data)

Create {TJsonRpcError} object with error code -32700.

Params:

• data: {String} - error text

Class: TJsonRpcNotificationObject

Describes JSON-RPC 2.0 Notification object. Realizes interface {IJsonRpcMessage}.

Constructor: TJsonRpcNotificationObject.Create(method[,params])

Creates an instance.

Params:

• method: {String}
• params: {TSuperArray|ISuperObject} optional

For TSuperArray use SA() or SO([array, items]).

Class Method: TJsonRpcNotificationObject.AsJsonObject

Returns object as {ISuperObject}

Class: TJsonRpcRequestObject

Describes JSON-RPC 2.0 Request object. Realizes interface {IJsonRpcMessage}.

Constructor: TJsonRpcRequestObject.Create(id, method[,params])

Creates an instance.

Params:

• id: {String}
• method: {String}
• params: {TSuperArray|ISuperObject} optional

For TSuperArray use SA() or SO([array, items]).

Class Method: TJsonRpcRequestObject.AsJsonObject

Returns object as {ISuperObject}

Class: TJsonRpcSuccessObject

Describes JSON-RPC 2.0 Success object. Realizes interface {IJsonRpcMessage}.

Constructor: TJsonRpcSuccessObject.Create(id, result)

Create a {TJsonRpcSuccessObject} instance.

Params:

• id: {String}
• result: {ISuperObject}

To place scalar value as result use superobject as wrapper: SO('string value'); SO(921)

Class Method: TJsonRpcSuccessObject.AsJsonObject

Returns object as {ISuperObject}

Class: TJsonRpcErrorObject

Describes JSON-RPC 2.0 Error object. Realizes interface {IJsonRpcMessage}.

Constructor: TJsonRpcErrorObject.Create(id, method[,params])

Creates an instance.

Params:

• id: {String}
• result: {ISuperObject}

To place scalar value as result use superobject as wrapper: SO('string value'); SO(921)

Class Method: TJsonRpcErrorObject.AsJsonObject

Returns object as {ISuperObject}