fixed dependency

composer.json

@@ -13,7 +13,7 @@
     ],
     "require": {
         "php": ">=5.5.0",
-        "guzzlehttp/guzzle": "^6.0",
+        "guzzlehttp/guzzle": "^5.0|^6.0",
         "symfony/serializer": "^2.0|^3.0"
     },
     "require-dev": {

src/Josser/Client/Transport/Guzzle5Transport.php

@@ -0,0 +1,69 @@
+<?php
+
+/*
+ * This file is part of the Josser package.
+ *
+ * (C) Alan Gabriel Bem <[email protected]>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Josser\Client\Transport;
+
+use GuzzleHttp\Client;
+use Josser\Exception\TransportFailureException;
+
+/**
+ * JSON-RPC http transport with Guzzle 5.
+ *
+ * @author Alan Gabriel Bem <[email protected]>
+ */
+class Guzzle5Transport implements TransportInterface
+{
+    /**
+     * Guzzle http client.
+     *
+     * @var Client
+     */
+    private $guzzle;
+
+    /**
+     * @param Client $guzzle
+     */
+    public function __construct(Client $guzzle)
+    {
+        $this->guzzle = $guzzle;
+    }
+
+    /**
+     * @return Client
+     */
+    public function getGuzzle()
+    {
+        return $this->guzzle;
+    }
+
+    /**
+     * Send data to remote JSON-RPC service over HTTP.
+     *
+     * @throws \Josser\Exception\TransportFailureException
+     * @param mixed $data
+     * @return string
+     */
+    public function send($data)
+    {
+        try {
+            $response = $this->guzzle->post(null, [
+                'body' => $data,
+                'headers' => [
+                    'Content-Type' => 'application/json',
+                ]
+            ]);
+            return $response->getBody()->getContents();
+        } catch (\Exception $e) {
+            $error = sprintf('JSON-RPC http connection failed. Remote service at "%s" is not responding.', $this->guzzle->getBaseUrl());
+            throw new TransportFailureException($error, null, $e);
+        }
+    }
+}

src/Josser/Client/Transport/HttpTransport.php → src/Josser/Client/Transport/Guzzle6Transport.php

@@ -15,11 +15,11 @@
 use Josser\Exception\TransportFailureException;
 
 /**
- * JSON-RPC http transport.
+ * JSON-RPC http transport with Guzzle 6.
  *
  * @author Alan Gabriel Bem <[email protected]>
  */
-class HttpTransport implements TransportInterface
+class Guzzle6Transport implements TransportInterface
 {
     /**
      * Guzzle http client.