Help with remote xmlrpc server

[Mark Nelson]

Hi All,

I am very new to Robot Framework, so please excuse if this is a stupid question, but I have searched all over the internet and cannot find an answer.

I am trying to write a remote server using Apache xmlrpc.  I have a simple test case right now to see how it works.

Here is my remote server class:

package com.mark;

public class Robot {
 
  public String[] get_keyword_names() {
    return new String[] { "ping" };
  }

  public String ping(String input) {
    return "pong " + input;
  }

}

And I have an XmlRpcServer.properties which says:

Robot=com.mark.Robot

I have this deployed on an app server, and it is at http://server:port/myRobot/xmlrpc

I wrote a python client to test it and that works fine:

import xmlrpclib

# Create an object to represent our server.
server_url = 'http://server:port/myRobot/xmlrpc';
server = xmlrpclib.Server(server_url);

# Call the server and get our result.
result = server.Robot.get_keyword_names()
print result

# test ping
result = server.Robot.ping('frank')
print result

It outputs:

['ping']
pong frank

So it seems the server is working from a purely xmlrpc point of view.

Now I have a test like this:

*** Settings ***
Library  Remote  http://server:port/myRobot/xmlrpc  WITH NAME  Robot

*** Test Cases ***

Ping Test
   ${pong} =                 Robot.ping     bob
   Strings Should Be Equal   ${pong}        pong bob

But this is giving me an error that it can't find get_keyword_names:

==============================================================================
Acceptance                                                                   
==============================================================================

[ ERROR ] Unexpected error: Connecting remote server at http://server:port/myRobot/xmlrpc failed: <Fault 0: 'No such handler: get_keyword_names'>
Traceback (most recent call last):
  File "/home/hudson/.m2/repository/org/robotframework/robotframework/2.7.7/robotframework-2.7.7.jar/Lib/robot/libraries/Remote$py.class", line 43, in get_keyword_names


I have tried various alternatives:
- removing the WITH NAME Robot
- putting /Robot on the end of the URL
- using ping instead of Robot.ping

But I just cant seem to get it to work, and I can't really find an example that shows both sides - they all show only the server or the client/test, but don't put it all together.

Would really appreciate any help or advice.

Thanks in advance,
Mark Nelson

[Kevin O.]

The problem is that the remote library API protocol requires the handlers to have no prefix and you are using prefix "Robot". IOTW Remote library is trying to invoke get_keyword_names and you have Robot.get_keyword_names.

Out of the box, Apache XMLRPC server does not have a way to add a handler without a prefix (also known as a default handler).

I solved this by extending AbstractReflectiveHandlerMapping and providing a method to remove all the prefixes (e.g. move from /foo.runKeyword to /runKeyword) when designing jrobotremoteserver.

In RemoteApplications, this was solved by implementing a full custom XmlRpcHandler.

Another solution would be to use existing code.

jrobotremoteserver is servlet based and you should be able to add it to your app/web server using org.robotframework.remoteserver.servlet.RemoteServerServlet.

So your test code should like like this:

result = server.get_keyword_names() 

instead of:

result = server.Robot.get_keyword_names() 

Kevin

[David]

That's insightful info Kevin, thanks. I never had to use (and thus not really tested) remote libraries with aliasing/prefixing library keywords. So my Perl and .NET/C# remote servers may have this problem as well, I'll have to look into them sometime.

[Mark Nelson]

Thanks a lot for your help Kevin.  I got my library working.

In case anyone else has a similar interest, here is what I did:

my test:

*** Settings ***
Library  Remote  http://server:port/myRobot/xmlrpc 

*** Test Cases ***

Ping Test

   ${pong} =                    ping           bob
   Should Be Equal as Strings   ${pong}        pong bob

The web.xml for the web app:

<?xml version="1.0" encoding="UTF-8"?>
<web-app version="3.0"
         xmlns="http://java.sun.com/xml/ns/javaee"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd" >

  <session-config>
    <session-timeout>30</session-timeout>
  </session-config>
  <welcome-file-list>
    <welcome-file>index.html</welcome-file>
  </welcome-file-list>
  <servlet>
    <servlet-name>XmlRpcServlet</servlet-name>
    <servlet-class>com.mark.MyXmlRpcServlet</servlet-class>
    <init-param>
      <param-name>enabledForExtensions</param-name>
      <param-value>true</param-value>
    </init-param>
  </servlet>
  <servlet-mapping>
    <servlet-name>XmlRpcServlet</servlet-name>
    <url-pattern>/xmlrpc</url-pattern>
  </servlet-mapping>
</web-app>

My remote library class:

package com.mark;

import java.util.Map;
import java.util.HashMap;

public class Robot {
 
  public String ping(String input) {
    System.out.println("[MARK] Robot.ping()");
    return "pong " + input;
  }

  //
  // methods required by the robotframework remote library protocol follow
  //
  public String[] get_keyword_names() {
    //System.out.println("[MARK] Robot.get_keyword_names()");
    return new String[] { "ping" };
  }

  public Map<String, Object> run_keyword(String keyword, Object[] args) {
    //System.out.println("[MARK] Robot.run_keyword()");
    HashMap<String, Object> kr = new HashMap<String, Object>();
    try {
      kr.put("status", "PASS");
      kr.put("error", "");
      kr.put("traceback", "");
      Object retObj = "";
      // run the right method
      if (keyword.equalsIgnoreCase("ping")) {
        retObj = ping((String)args[0]);
      } else {
        kr.put("status", "FAIL");
        kr.put("return", "");
        kr.put("error", "");
        kr.put("traceback", "");
      }
      kr.put("return", retObj);
    } catch (Throwable e) {
      e.printStackTrace(System.out);
    }
    return kr;
  }

}


my custom handler:

/*
 * Adapted from https://github.com/ombre42/jrobotremoteserver/blob/master/src/main/java/org/robotframework/remoteserver/xmlrpc/ReflectiveHandlerMapping.java
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package com.mark;

import java.util.HashMap;
import java.util.Map;
import java.util.Map.Entry;
import java.util.Set;

import org.apache.xmlrpc.XmlRpcException;
import org.apache.xmlrpc.server.AbstractReflectiveHandlerMapping;

public class HandlerMapping extends AbstractReflectiveHandlerMapping {

    /**
     * Removes the prefixes from all keys in this handler mapping assuming a
     * String was used as the key and period was
     * used as a separator. Example: Robot.getInvoice -> getInvoice
     */
    @SuppressWarnings("unchecked")
    public void removePrefixes() {
      //System.out.println("[MARK] entering HandlerMapping.removePrefixes()");
      Map<String, Object> newHandlerMap = new HashMap<String, Object>();
      for (Entry<String, Object> entry : (Set<Entry<String, Object>>) this.handlerMap.entrySet()) {
        String newKey = (String) entry.getKey();
        if (entry.getKey() instanceof String) {
          String key = (String) entry.getKey();
          if (key.contains(".")) {
            newKey = key.substring(key.lastIndexOf(".") + 1);
          }
        }
        newHandlerMap.put(newKey, entry.getValue());
      }
      this.handlerMap = newHandlerMap;
    }

my custom servlet:

    /**
     * Adds handlers for the given object to the mapping. The handlers are build by invoking
     * {@link #registerPublicMethods(String, Class)}.
     *
     * @param pKey
     *            The class key, which is passed to {@link #registerPublicMethods(String, Class)}.
     * @param pClass
     *            Class, which is responsible for handling the request.
     */
    public void addHandler(String pKey, Class<?> pClass) throws XmlRpcException {
      //System.out.println("[MARK] entering HandlerMapping.addHandler()");
      registerPublicMethods(pKey, pClass);
    }
}

package com.mark;

import org.apache.xmlrpc.XmlRpcException;
import org.apache.xmlrpc.server.XmlRpcHandlerMapping;
import org.apache.xmlrpc.webserver.XmlRpcServlet;

public class MyXmlRpcServlet extends XmlRpcServlet  {

  @Override
  protected XmlRpcHandlerMapping newXmlRpcHandlerMapping() throws XmlRpcException {
    //System.out.println("[MARK] entering MyXmlRpcServlet.newXmlRpcHandlerMapping()");
    HandlerMapping mapping = new HandlerMapping();
    mapping.addHandler(com.mark.Robot.class.getName(), com.mark.Robot.class);
    mapping.removePrefixes();
    return mapping;
  }

}


Out of interest, I did not want to run the server and fire up a new listener/thread on another port.  I wanted to have the servlet run just in the normal container.  This way, i can take advantage of the container/app server's tuning, thread and workload management, which I need to do in this particular exercise.

Thanks again for your help.

Best Regards,

Mark Nelson

[David]

Also, just curious if this handler prefix issue applied to the Python and Ruby remote servers and if so, how it was addressed for them.

On Thursday, May 16, 2013 5:33:18 AM UTC-7, Kevin O. wrote:

[Kevin O.]

Glad to hear you got it working and thanks for sharing.

When I enhanced the Java server to support multiple libraries, I did not realize you could use a URL with a path, so I used different ports instead.

This was pretty dumb and big mistakes can happen when you are the solo developer.

In the next release I will remove all the multiple port functionality and switch to multiple paths.

I have also put in an enhancement to make the servlet more portable for situations like yours.

@David

Neither the C# or Perl servers appear to have this issue.

Maybe you are thinking of the fact that the Perl server binds to path /RPC2 instead of /.

That is a different issue.

The method prefix issue has to do with how the contents of the methodCall/methodName element inside the request body/XML are mapped to a method.

As usual the Java folks made it complicated and the Python/Ruby folks made something that "just works" :P

Even the Redstone server required prefixes until recent versions.