JSON-RPC 2.0 Implementation for PHP

Features

• JSON-RPC 2.0 specification compliant
• Support for single requests, batch requests and notifications
• Server implementation with PSR-11 container integration
• Client implementation with pluggable transport layer
• Clean exception-based error handling
• Immutable value objects for requests, responses, and errors

Requirements

• PHP 8.4 or higher
• Composer
• PSR-11 compatible container (e.g., PHP-DI, Symfony DependencyInjection)

Installation

composer req ellinaut/json-rpc

Quick Start

Server Usage

1. Implement a Remote Procedure

<?php

use Ellinaut\JsonRpc\Server\RemoteProcedure;
use Ellinaut\JsonRpc\Exception\InvalidParamsException;

class MathAddProcedure implements RemoteProcedure
{
    public function validate(array $params): void
    {
        if (!isset($params['a'], $params['b'])) {
            throw new InvalidParamsException('Missing required parameters: a, b');
        }
        
        if (!is_numeric($params['a']) || !is_numeric($params['b'])) {
            throw new InvalidParamsException('Parameters must be numeric');
        }
    }
    
    public function execute(array $params, string|int|float|null $id): mixed
    {
        return $params['a'] + $params['b'];
    }
}

2. Set Up the Server

<?php

use Ellinaut\JsonRpc\Server\JsonRpcServer;
use Psr\Container\ContainerInterface;

// Assuming you have a PSR-11 container
$container = new YourContainer();
$container->set('math.add', new MathAddProcedure());

$server = new JsonRpcServer($container);

// Handle incoming request
$jsonInput = file_get_contents('php://input');
$response = $server->handle($jsonInput);

header('Content-Type: application/json');
echo $response;

3. Make Requests

curl -X POST http://your-server/endpoint \
  -H "Content-Type: application/json" \
  -d '{
    "jsonrpc": "2.0",
    "method": "math.add",
    "params": {"a": 5, "b": 3},
    "id": 1
  }'

4. Parameter Validation

The server automatically validates parameters before executing procedures:

// Valid request - passes validation
{"jsonrpc": "2.0", "method": "math.add", "params": {"a": 5, "b": 3}, "id": 1}
// Response: {"jsonrpc": "2.0", "result": 8, "id": 1}

// Invalid request - fails validation
{"jsonrpc": "2.0", "method": "math.add", "params": {"a": "invalid"}, "id": 1}
// Response: {"jsonrpc": "2.0", "error": {"code": -32602, "message": "Parameters must be numeric"}, "id": 1}

Validation Features:

• Pre-execution validation: validate() method is called before execute()
• Exception-based: Throw InvalidParamsException for validation errors
• Automatic error responses: Validation failures return proper JSON-RPC error responses
• Batch support: Each request in a batch is validated independently
• Notification handling: Validation errors in notifications still return error responses

Client Usage

1. Implement a Transport

<?php

use Ellinaut\JsonRpc\Client\TransportInterface;

class HttpTransport implements TransportInterface
{
    public function __construct(private string $endpoint) {}
    
    public function send(string $json): ?string
    {
        $context = stream_context_create([
            'http' => [
                'method' => 'POST',
                'header' => 'Content-Type: application/json',
                'content' => $json
            ]
        ]);
        
        return file_get_contents($this->endpoint, false, $context) ?: null;
    }
}

2. Use the Client

<?php

use Ellinaut\JsonRpc\Client\JsonRpcClient;
use Ellinaut\JsonRpc\Model\Value\Request;

$transport = new HttpTransport('http://your-server/endpoint');
$client = new JsonRpcClient($transport);

// Single request
$request = new Request('math.add', ['a' => 5, 'b' => 3], 1);
$response = $client->send($request);

if ($response) {
    echo "Result: " . $response->data . "\n";
}

// Batch requests
$requests = [
    new Request('math.add', ['a' => 1, 'b' => 2], 1),
    new Request('math.multiply', ['a' => 3, 'b' => 4], 2),
    new Request('notification', ['message' => 'hello'], null) // Notification
];

$responses = $client->sendBatch($requests);
foreach ($responses as $response) {
    echo "Response ID {$response->id}: {$response->data}\n";
}

Development

Using Docker

Start the development environment:

docker-compose up

Access the PHP container:

docker-compose exec php bash

Running Tests

# Local
vendor/bin/phpunit

# With coverage (requires Xdebug)
vendor/bin/phpunit --coverage-html coverage/

# In Docker
docker-compose run --rm php vendor/bin/phpunit

# With coverage in Docker
docker-compose run --rm php vendor/bin/phpunit --coverage-html coverage/

Architecture

Core Components

Server Components

• JsonRpcServer: Main server handling requests, parameter validation, and routing to procedures
• RemoteProcedure: Interface for implementing RPC methods with validation and execution

Client Components

• JsonRpcClient: Client for making JSON-RPC requests with Generator-based batch support
• TransportInterface: Pluggable transport layer for different communication methods

Shared Components

• Value Objects: Immutable Request, Response, and Error objects
• Exceptions: Specialized JSON-RPC error exceptions

Error Handling

The library provides specific exceptions for different JSON-RPC error scenarios:

• InvalidJsonException: Malformed JSON
• InvalidRequestException: Invalid request structure
• InvalidMethodException: Method not found
• InvalidParamsException: Invalid method parameters
• InternalErrorException: Internal server errors

All exceptions extend JsonRcpException and are automatically converted to proper JSON-RPC error responses.

Key Features

Generator-based Batch Processing

The client uses PHP Generators for memory-efficient batch request processing:

$responses = $client->sendBatch($requests); // Returns Generator<Response>
foreach ($responses as $response) {
    // Process each response as it's yielded
    echo $response->data;
}

Transport Abstraction

The client supports different transport mechanisms through the TransportInterface:

• HTTP Transport: For REST API communication
• Socket Transport: For direct TCP communication
• Mock Transport: For testing
• Custom Transports: Implement your own transport layer

Parameter Validation

The server provides built-in parameter validation:

• Two-phase execution: validate() called before execute() for each procedure
• Early validation: Parameters are validated before any business logic execution
• Consistent error handling: Validation exceptions automatically converted to JSON-RPC error responses
• Batch validation: Each request in a batch is validated independently

Error Handling

Both client and server provide comprehensive error handling:

• Server: Catches exceptions and converts them to JSON-RPC error responses
• Client: Wraps transport errors in JsonRcpException for consistent error handling
• Validation errors: InvalidParamsException thrown from validate() method returns proper error responses