Software Development

Simple Meddler scripts for faking web service responses

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I recently discovered Meddler which is an HTTP generator based on JScript. Since there were not many samples to find and Google wasn’t really of much help here, I figured I could share the scripts I write here. Maybe it helps someone out, and even more likely, I will probably have to look back at this at some time since I will forget 😛

To use these, simply load up the script in Meddler, hit compile and you can talk to it through http://localhost:8088/.

Map path to file

This script responds with an XML file corresponding to whatever the first chunk of the request path was. For example if you tried to get http://localhost:8088/foobar, it would try to return foobar.xml from whatever directory your script is located.

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import Meddler;
import System;
import System.IO;
import System.Text.RegularExpressions;

class Handlers
{
  static function OnConnection(session: Session)
  {
    var headers: ResponseHeaders = new ResponseHeaders();
   
    try
    {
      if( ! session.ReadRequest())
        return;
     
      if(session.requestHeaders.Path == "/favicon.ico")
        return;    
     
      var filename:String = Path.GetDirectoryName(MeddlerObject.RunningScript)
        + Path.DirectorySeparatorChar
        + Regex.Match(session.requestHeaders.Path, "\\w+").Value
        + ".xml";
      var response:byte[] = Utilities.FileToByteArray(filename, false);
     
      headers.Status = "200 OK";
      headers["Connection"] = "close";
      headers["Content-Type"] = "text/xml; charset=utf-8";
      session.WriteString(headers);
      session.WriteBytes(response);
     
      MeddlerObject.Log.LogString(session.requestHeaders.Path
        + "\t" + filename);
    }
    catch(e)
    {
      MeddlerObject.Log.LogString(e);
     
      headers.Status = "500 Internal Server Error";
      headers["Connection"] = "close";
      headers["Content-Type"] = "text/plain; charset=utf-8";
      session.WriteString(headers);
      session.WriteLine(e);
    }
    finally
    {
      session.CloseSocket();
    }
  }
}

Alternating responses

This script alternates between serving two different XML files. One containing a regular response, and one with an error. The files are expected to be in the same directory as the script itself. I used this to test an ESB process to make sure it handled both good and bad responses properly.

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import Meddler;
import System;
import System.Net.Sockets;
import System.IO;

class Handlers
{
  static const responses:String[] = [
    "response.xml",
    "error.xml",
    ];
   
  static var n:int;
     
  static function OnConnection(session: Session)
  {
    var headers: ResponseHeaders = new ResponseHeaders();
 
    try
    {
      if( ! session.ReadRequest())
        return;
     
      if(session.requestHeaders.Path == "/favicon.ico")
        return;
     
      var filename:String = Path.GetDirectoryName(MeddlerObject.RunningScript)
        + Path.DirectorySeparatorChar
        + responses[n % responses.Length];
      var response:byte[] = Utilities.FileToByteArray(filename, false);
     
      headers.Status = "200 OK";
      headers["Connection"] = "close";
      headers["Content-Type"] = "text/xml; charset=utf-8";
      session.WriteString(headers);
      session.WriteBytes(response);
     
      MeddlerObject.Log.LogString(n
        + "\t" + session.requestHeaders.Path
        + "\t" + filename);
      n++;
    }
    catch(e)
    {
      MeddlerObject.Log.LogString(e);
     
      headers.Status = "500 Internal Server Error";
      headers["Connection"] = "close";
      headers["Content-Type"] = "text/plain; charset=utf-8";
      session.WriteString(headers);
      session.WriteLine(e);
    }
    finally
    {
      session.CloseSocket();
    }
  }
}