Simon's Tech Blog

Accessing a Restful service is actually no big deal, but it took me quite a while to figure out some details. So here’s a short description of it.

First of all, we build a small Zend Rest Service with two ping methods and save it as MyRestService.php.

<?php

class MyRestService {
 /**
 * @param string $name
 * @return string
 */
 public function ping($name) {
 return 'Hello ' . $name;
 }
}

require 'Zend/Rest/Server.php';

$server = new Zend_Rest_Server ( );
$server->setClass ( 'MyRestService' );
$server->handle();

require 'Zend/Rest/Server.php';

$server = new Zend_Rest_Server ( );
$server->setClass ( 'MyRestService' );
$server->handle();

We can now allready access our service with the browser by entering the URL http://localhost/MyRestService.php?method=ping&name=Simon. The service returns the answer as XML.

<MyRestService generator="zend" version="1.0">
 <ping>
 <response>Hello Simon</response>
 <status>success</status>
 </ping>
</MyRestService>

As you can see the call as well as the answer are really straightforward and easy to unserstand. We’re going now to access our service from C#.

public void CallRest() {
 string methodName = "ping";
 string name = "Simon";

 // Build the URL with the parameters
 StringBuilder sb = new StringBuilder();
 sb.Append("http://localhost/MyRestService.php");
 sb.Append(string.Format("?method={0}", HttpUtility.UrlEncode(methodName)));
 sb.Append(string.Format("&name={0}", HttpUtility.UrlEncode(name)));

 // Download the service answer as string
 Uri address = new Uri(sb.ToString());
 WebClient serviceClient = new WebClient();
 serviceClient.DownloadStringCompleted += new DownloadStringCompletedEventHandler(serviceClient_DownloadStringCompleted);
 serviceClient.DownloadStringAsync(address);
}

private void serviceClient_DownloadStringCompleted(object sender, DownloadStringCompletedEventArgs e) {
 try {
 // Check for service error
 if (e.Error != null)
 throw e.Error;

 // Load the result as XML for easy Linq access
 XElement elem = XElement.Parse(e.Result);

 // Check the return status
 string status = (string)(from el in elem.Descendants("status") select el).First();

 if ("success".Equals(status)) {
 // Get the response
 string resp = (string)(from el in elem.Descendants("response") select el).First();
 MessageBox.Show(resp, "The Restservice says...", MessageBoxButton.OK);

 } else if ("failed".Equals(status)) {
 // Get the error message
 string errmsg = (string)(from el in elem.Descendants("message") select el).First();
 throw new Exception(errmsg);

 } else {
 throw new Exception(string.Format("Unknown Rest status: {0}", status));
 }
 } catch (Exception exp) {
 MessageBox.Show(exp.ToString(), "Error", MessageBoxButton.OK);
 }
}

When we run the code a MessageBox with the service response should pop up.

So, this was the part I figured out quite fast. But what happens if you change the service function so somewhat like this:

/**
* @param array $names
* @return string
*/
public function ping($names){
 return $names['p2'];
}

It took me some time to figure out that the answer is quite easy. Let’s change the C# function to fit the array parameter.

public void CallRest() {
 string methodName = "ping";
 string[] names = { "Simon", "John", "Bill" };

 // Build the URL with the parameters
 StringBuilder sb = new StringBuilder();
 sb.Append("http://localhost/MyRestService.php");
 sb.Append(string.Format("?method={0}", HttpUtility.UrlEncode(methodName)));

 for (int i = 0; i < names.Length; i++)
 sb.Append(string.Format("&names[p{0}]={1}", i, HttpUtility.UrlEncode(names[i])));

 // Download the service answer as string
 Uri address = new Uri(sb.ToString());
 WebClient serviceClient = new WebClient();
 serviceClient.DownloadStringCompleted += new
 DownloadStringCompletedEventHandler(serviceClient_DownloadStringCompleted);
 serviceClient.DownloadStringAsync(address);
}

As you can see I just add the parameter as everybody would access an array. And once again, you can also access the service direct with your browser unter the URL http://localhost/MyRestService.php?method=ping&names[p0]=Simon&names[p1]=John&names[p2]=Bill