Planet ObjectWeb

Orbeon: Keeping your session alive

Tue, 29 Jan 2008 15:36:46 +0000

A couple of weeks ago I attempted to order prints from Flickr. I added a few photos to my cart and was redirected to a service called QOOP. This has a neat interface that allows you organize photos for printing in a book format. I played a bit with the interface and then was caught by other tasks. When I came back to my browser window and attempted to preview the photo album, I got a wonderful error message about a session having expired. The result: my album was lost. I gave up.

My adventure with expired sessions is quite common and I can bet you have had this kind of issues in the past. The least that can be said about this is that it is not user-friendly!

To address this kind of issues, we recently introduced a new feature in Orbeon Forms called the “session heartbeat”. The idea is that if you happen to leave a browser window open on your computer, chances are that you will get back to that window and keep using the application. The last thing you want to happen when you come back is lose your session and therefore your data, as happened to me.

This is not always a correct guess of course: you may just happen to leave a window or tab open without planning to use it again. Conversely you may have a page which is not actually visible, for example in your browser history, yet you will come back to it. This approach wouldn’t be good for banking applications either. Still, in many situations, such as filling-out large forms, it sounds like a good idea to keep your session alive for open pages.

To achieve this goal you could make all server sessions longer. However this is harder to configure for the application developer, and this won’t discriminate between pages that are actually open on a client and the ones that are not. And while it may be ideal to have infinitely long sessions, unfortunately many applications are not ready for this kind of approach.

So we turned to the idea of implementing a “session heartbeat”. Here is how this works:

When this feature is enabled, an open XForms page regularly pings the server through Ajax to keep the current session alive.
The ping delay is automatically computed based on the server’s session timeout. The client pings the server at 80% of the session expiration time after the last interaction with the server.
We are careful not to hit the XForms engine too much, in fact we do a very limited amount of work on the server for each ping, so they should run fast.
XForms state information for pages hit with the heartbeat just migrates to the disk store over time if RAM is used by other pages, so keeping even large numbers of pages open should not have any negative impact on server RAM.
When a user gets back to using the page, state information migrates back from disk to RAM, and the page will be live again.
Sessions do eventually expire as nobody keeps a browser open forever.

Note that whenever an application keeps sessions alive for a long time, it is a good idea to keep as little data as possible in the session. The Orbeon Forms XForms engine itself uses a global state store and does not use session objects for storage, but do remember to keep your sessions small!

Hopefully, this will help prevent many occurrences of the infamous “session expired” error message. The beauty of it is that as an Orbeon Forms application developer you don’t have to worry about anything: the session heartbeat is enabled by default (but it can be turned off globally in properties.xml or individually for each page).

Christophe Hamerling: Too many open files IOException with large number of Axis2 Servic

Sun, 27 Jan 2008 23:50:23 +0000

This is a problem we met in the PEtALS SOAP Binding Component with large number of Axis2 Service Clients.
In this case, this error happens when too many sockets are open ant are waiting to be closed. Even if I have found some JIRAs about this problem and possible solutions, the only one which work for us is to cleanup the connection after each service call.
It is done like this :

...

ServiceClient client = new ServiceClient(null, service);

Options options = new Options();

...

options.setCallTransportCleanup(true);

client.setOptions(options);

OMElement outBodyElement = null;

try {

outBodyElement = serviceClient.sendReceive(soapAction, inBodyElement);

} catch (AxisFault e) {

throw e;

}

After 10 minutes test with 200 threads creating 'one shot ' ServiceClient and almost 275000 service calls, all worked fine.

Christophe Hamerling: Going to JavaPolis 07

Sun, 27 Jan 2008 23:50:23 +0000

See you next week JavaPolis '07 on the OW2 Consortium booth to talk about and make some 'demos' of the PEtALS Enterprise Service Bus project.

Christophe Hamerling: PEtALS Standalone 1.4.3

Sun, 27 Jan 2008 23:50:23 +0000

PEtALS Standalone platform 1.4.3 is out. This is a maintenance release.
Look at the release notes for more details.

Christophe Hamerling: CIMERO2 Editor for PEtALS ESB

Sun, 27 Jan 2008 23:50:23 +0000

The CIMERO2 editor is an Eclipse plugin originally developed by Bull. This plugin provides features to create a visual representation of your Enterprise Service Bus based architecture. After the design step, the plugin offers the possibility to generate the JBI artifacts (Service Assemblies), and the Ant deployment scripts which will be used to deploy the configuration on the ESB.

We, at eBM WebSourcing, are currently working on better integration of the PEtALS JBI components. You can find a Flash demonstration on how we you can use this plugin on the PEtALS project website demonstration page.

Finally, it is good to notice that this plugin is currently under integration into the Eclipse SOA Tools Platform project (Eclipse STP).

Christophe Hamerling: Installing SVN Client on Mac OSX

Sun, 27 Jan 2008 23:50:23 +0000

I am happy to see that Fink (http://finkproject.org/) is no more needed to easily install a Subversion client on Mac OSX. A client has been packaged by this guy Martin Ott (http://homepage.mac.com/martinott/).

Installation done by clicking on the package...

I am also happy to see that there is a Subversion GUI client for OSX. Working with terminal is cool but sometimes clicking on the mouse is not so bad...

You can found this client on 'La chose interactive' website (http://www.lachoseinteractive.net/fr/communaute/subversion/).

Configuration seems very intuitive... Going to test it for PEtALS project...

Christophe Hamerling: PEtALS PACK 2.0

Sun, 27 Jan 2008 23:50:23 +0000

Friday (evening) September 28th 2007

PEtALS ESB 2.0 is finally out!
It is released at the same time as a 'pack' including all new/compatible modules which have been developed since months.
These modules are :

The PEtALS kernel 2.0
A new Web Console for monitoring and administration
The Component Development Kit 3.0 : Library and tools for easily and rapidly create JBI compliant components.
A collection of JBI compliant components (including new ones like XMPP, HTTP binding components, EIP, RMI Service Engines)
An Eclipse plugin for JBI artifacts development and administration
Docbook based documentation
Brand new website & logo

Complete release note will be available on the PEtALS Website.

Christophe Hamerling: PEtALS last week releases

Sun, 27 Jan 2008 23:50:23 +0000

We have done some releases last week :

1. petals-standalone 1.4 :
    - Integration of a faster message transporter (Dream based)
    - Load balancing
    - Robustness
    - and of course several bug fixes and code optimization

2. petals-component-framework 2.0 :
    - This framework replaces the Component Development Kit (also known as CDK). It allows developers to quickly create powerful JBI components.

3. petals-bc-soap 2.0 :
    - Based on the petals-component-framework.
    - WS security
    - WS notification

Zip archives and documentation are available for download on the PEtALS downloads page.

Christophe Hamerling: Road to PEtALS 2.0

Sun, 27 Jan 2008 23:50:23 +0000

PEtALS 2.0 is on the way. The beta version will be out in few weeks with cool features :

Eclipse plugin for development, test and integration
Multi-transporter with Dream for synchronous communication and Joram for asynchronous communication
RMI client for direct access to the bus API
UDDI registry Service Engine
EIP Service Engine
Enhanced SOAP Binding Component
Component Development Kit 2.0
JBOSS integration
Failure management / load balancing
Large deployment with Fractal Deployment Framework
Performance optimisations
Enhancements in monitoring tool
New docbook documentation

Christophe Hamerling: PEtALS Azalee Pack

Sun, 27 Jan 2008 23:50:23 +0000

The PEtALS Azalée Pack is finally out. It includes all the latest stable versions of project artefacts.
You can download it here and get release note here.

Technorati Tags open,source,petals,jbi,soa,esb,webservices

Christophe Hamerling: PEtALS community news - May

Sun, 27 Jan 2008 23:50:23 +0000

PEtALS news #1, 2007 May 16th

The PEtALS community is growing. Thanks to everyone for the interest you give to the project. Here is the first newsletter dedicated to this great project...

Releases and more

Core release 1.3 has been delayed and is now planned by the end of the month. Finally, we will release what we call a PEtALS Pack. This pack includes all the latest stable versions of PEtALS modules.
We have especially worked on :

New fractal (A component framework) architecture

Add static JNDI configuration : You can now define you PEtALS network topology
Lot of refactoring
Stability and bug fixes

A new component is available on the objectweb forge : The FTP binding component.
CDK 1.3 has been released on April the 25th 2007. It includes new configuration features through JMX during component installation.

More information on the future release note...

Main developments

Marie Sauvage (eBM WebSourcing) is working on the next version of the web administration tool. It will include lot of features to manage and administrate all the platform through a nice interface.
Nicolas Salatge (eBM WebSourcing) who has joined the developers team since a couple of months, has just completed the new PEtALS 'Fractalization'. Most of PEtALS modules are now Fractal components.
Dong Zhao has developped an OSGI version of PEtALS. This will allow to run PEtALS on any OSGI implementation (JOnAS5 and more...)
An eclipse plugin is under validation process. It will be available soon.
We are improving the CDK features again and again
Guillaume Decarnin (Openwide) is working on csv, xquare and forward components. These components will be soon based on the new CDK.

Documentation

Each module will soon have its own mini site (maven generated) in replacement of the wiki pages which are a little boring...
We are also working on a new user guide based on DocBook tools.

Others

A flash version of the travel agency demo of available here.
Artefacts are now available to the maven community on the objectweb maven repository http://maven.objectweb.org

Please do not hesitate to send your comments, ideas, and more...

Technorati Tags news,petals

Christophe Hamerling: Creating fully compatible JBI components

Sun, 27 Jan 2008 23:50:23 +0000

As JBI container developers (PEtALS), we have created a framework which allows developers to easily create JBI components.

This Component Development Kit (also called PEtALS CDK) is based on the JBI specification and allows to create components which are 100% compatible with the JBI specification. In other words, you can use the CDK to create components that can be installed on all JBI implementations.

Note that most of the PEtALS components (Service Engines and Binding Components) are based on this CDK.
An online documentation is available on the projet wiki here and you can download the CDK here.

Technorati Tags petals,jbi

Christophe Hamerling: Implementing the DynamicMBean interface

Sun, 27 Jan 2008 23:50:23 +0000

Implementing DynamicMBean interface

Introduction

Using JMX (Java Management eXtensions) to manage part of your application is a great java feature. The standard Mbeans mechanisms which consist of creating a class which implements an MBean interface is quite simple and already allows to manage most of your application.
In this article, I will describe how can we implements the DynamicMBean interface to do more 'complex' things. Especially, we will look on how we can we expose and modify a set of properties, and how can we expose methods by specifiing their names (The java code will be more clear than my poor english).

The following examples are taken from the work I have done on the PEtALS CDK (Component Development Kit) in order to expose a set of JBI extensions and bootstrap methods for management.

How to expose a set of properties?

The standards MBeans automatically expose the setters and getters methods as MBean attributes. Imagine that you have a set of properties (a HashMap/Properties...). How can you manage this object, how can you change a value in the set? Simply by creating an implementation of the DynamicMBean interface.

The following code snippet shows how we can do such a thing.

    /*
     * (non-Javadoc)
     * 
     * @see javax.management.DynamicMBean#getAttribute(java.lang.String)
     */
    public synchronized Object getAttribute(String attribute)
        throws AttributeNotFoundException, MBeanException, ReflectionException {

        String value = managedBootstrap.getComponentPropertiesManager()
            .getProperties().getProperty(attribute);
        if (value != null
            && !value
                .startsWith(ComponentPropertiesManager.MANAGED_METHOD_PREFIX)) {
            return value;
        } else {
            throw new AttributeNotFoundException("Attribute '" + attribute
                + "' does not exists");
        }
    }

    /*
     * (non-Javadoc)
     * 
     * @see javax.management.DynamicMBean#getAttributes(java.lang.String[])
     */
    public synchronized AttributeList getAttributes(String[] attributes) {
        AttributeList list = new AttributeList();
        for (String name : attributes) {
            String value = managedBootstrap.getComponentPropertiesManager()
                .getProperties().getProperty(name);
            if (value != null
                && !value
                    .startsWith(ComponentPropertiesManager.MANAGED_METHOD_PREFIX))
                list.add(new Attribute(name, value));
        }
        return list;
    }

    /*
     * (non-Javadoc)
     * 
     * @see javax.management.DynamicMBean#setAttribute(javax.management.Attribute)
     */
    public synchronized void setAttribute(Attribute attribute)
        throws AttributeNotFoundException, InvalidAttributeValueException,
        MBeanException, ReflectionException {
        String name = attribute.getName();
        if (managedBootstrap.getComponentPropertiesManager().getProperties()
            .getProperty(name) == null) {
            throw new AttributeNotFoundException(name);
        }

        Object value = attribute.getValue();
        if (!(value instanceof String)) {
            throw new InvalidAttributeValueException(
                "Attribute value not a string: " + value);
        }

        // set the property and save the properties file
        managedBootstrap.getComponentPropertiesManager().getProperties()
            .setProperty(name, (String) value);
        try {
            save();
        } catch (IOException e) {
            throw new MBeanException(e);
        }
    }

    /*
     * (non-Javadoc)
     * 
     * @see javax.management.DynamicMBean#setAttributes(javax.management.AttributeList)
     */
    public synchronized AttributeList setAttributes(AttributeList list) {
        AttributeList result = new AttributeList();

        for (Object object : list) {
            Attribute attr = (Attribute) object;
            String name = attr.getName();
            Object value = attr.getValue();
            if (managedBootstrap.getComponentPropertiesManager()
                .getProperties().getProperty(name) != null
                && value instanceof String) {
                managedBootstrap.getComponentPropertiesManager()
                    .getProperties().setProperty(name, (String) value);
                result.add(new Attribute(name, value));
            }
        }

        try {
            save();
        } catch (IOException e) {
            return new AttributeList();
        }
        return result;
    }

The previous methods are the ones which are called by the JMX implementation for management. In our case it is quite simple since a property entry is directly mapped into an attribute...

Note 1 : The managedBootstrap attribute is a class which contains a Properties object.
Note 2 : We persist the properties in a file each time a property is modified.

In order to expose these attributes, we will see later that we need to create a set of MBeanAttributeInfo that will be used by the getMBeanInfo method to create the information object used by JMX to expose all of this.

    /**
     * Dynamically get attributes for the MBean. The attributes are the ones
     * from the properties file.
     * 
     * @return
     */
    protected MBeanAttributeInfo[] getAttributesInfos() {
        // get the attributes names as sorted strings
        Set<String> attributeKeys = managedBootstrap
            .getComponentPropertiesManager().getExposedAttributeKeys();

        // build the MBeanAttributeInfo
        MBeanAttributeInfo[] attrs = new MBeanAttributeInfo[attributeKeys
            .size()];
        Iterator<String> it = attributeKeys.iterator();
        for (int i = 0; i < attrs.length; i++) {
            String name = it.next();
            attrs[i] = new MBeanAttributeInfo(name, "java.lang.String",
                "Property " + name, true, true, false);
        }
        return attrs;
    }

How to expose a set of methods?

Building the MBeanInfo

In the previous chapter, I have introduced how we can dynamically expose properties. Now we will focus on how we can choose the methods to expose through JMX. There are several methods to do this. Here I have choosen to expose only the public methods that are programatically defined in a list. I have choosen this simple way to allow the component developer to simply define the methods he wants to expose by returning a list of methods names... Simple and efficient!

    /**
     * Dynamically get the operations for the MBean. The operations are defined
     * in the properties manager with a special prefix.
     * 
     * @return
     */
    protected MBeanOperationInfo[] getOperationsInfos() {
        List<String> methods = managedBootstrap.getComponentPropertiesManager()
            .getExposedMethodNames();
        MBeanOperationInfo[] result = null;

        List<MBeanOperationInfo> operations = new ArrayList<MBeanOperationInfo>();
        Method methodList[] = managedBootstrap.getClass().getMethods();

        for (int i = 0; i < methodList.length; i++) {
            Method method = methodList[i];
            String name = method.getName();

            // add method if it has been defined by the user
            if (methods.contains(name)) {
                MBeanOperationInfo oper = new MBeanOperationInfo(
                    "Operation description", method);
                operations.add(oper);
            }
        }

        result = new MBeanOperationInfo[operations.size()];
        operations.toArray(result);

        return result;
    }

This time again, we are are creating a set of MBeanOperationInfo from a list methods names. We retrieve the methods from the class we want to manage from the managedBootstrap class by reflection.

This method will be then used to create the MBeanInfo that is returned by the method getMBeanInfo:

    /*
     * (non-Javadoc)
     * 
     * @see javax.management.DynamicMBean#getMBeanInfo()
     */
    public synchronized MBeanInfo getMBeanInfo() {
        // get the attributes
        MBeanAttributeInfo[] attrs = getAttributesInfos();
        // get the operations
        MBeanOperationInfo[] opps = getOperationsInfos();

        // create MBeanInfo with no constructors and no notifications
        return new MBeanInfo(this.getClass().getName(),
            "Property Manager MBean", attrs, null, opps, null);
    }

Invoking a method

Doing java reflection is out of this article scope. Have a look on the implementation to see how it is done.

Complete implementation

/**
 * PETALS - PETALS Services Platform.
 * Copyright (c) 2007 EBM Websourcing, http://www.ebmwebsourcing.com/
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 *
 * -------------------------------------------------------------------------
 * $Id$
 * -------------------------------------------------------------------------
 */
package org.objectweb.petals.component.common;

import java.io.IOException;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.util.ArrayList;
import java.util.Hashtable;
import java.util.Iterator;
import java.util.List;
import java.util.Set;

import javax.management.Attribute;
import javax.management.AttributeList;
import javax.management.AttributeNotFoundException;
import javax.management.DynamicMBean;
import javax.management.InvalidAttributeValueException;
import javax.management.MBeanAttributeInfo;
import javax.management.MBeanException;
import javax.management.MBeanInfo;
import javax.management.MBeanOperationInfo;
import javax.management.ReflectionException;
import javax.management.RuntimeOperationsException;

/**
 * The MBean used to expose component attributes and operations via JMX.
 * 
 * @author Christophe HAMERLING - eBMWebSourcing
 * 
 */
public class ExtensionMBean implements DynamicMBean {

    private ManagedBootstrap managedBootstrap;

    private final static Hashtable<String, Class<?>> primitiveClasses = new Hashtable<String, Class<?>>(
        8);
    {
        primitiveClasses.put(Boolean.TYPE.toString(), Boolean.TYPE);
        primitiveClasses.put(Character.TYPE.toString(), Character.TYPE);
        primitiveClasses.put(Byte.TYPE.toString(), Byte.TYPE);
        primitiveClasses.put(Short.TYPE.toString(), Short.TYPE);
        primitiveClasses.put(Integer.TYPE.toString(), Integer.TYPE);
        primitiveClasses.put(Long.TYPE.toString(), Long.TYPE);
        primitiveClasses.put(Float.TYPE.toString(), Float.TYPE);
        primitiveClasses.put(Double.TYPE.toString(), Double.TYPE);
    }

    /**
     * Creates a new instance of {@link ExtensionMBean}
     * 
     * @param bootstrap
     */
    public ExtensionMBean(ManagedBootstrap bootstrap) {
        this.managedBootstrap = bootstrap;
    }

    /*
     * (non-Javadoc)
     * 
     * @see javax.management.DynamicMBean#getAttribute(java.lang.String)
     */
    public synchronized Object getAttribute(String attribute)
        throws AttributeNotFoundException, MBeanException, ReflectionException {

        String value = managedBootstrap.getComponentPropertiesManager()
            .getProperties().getProperty(attribute);
        if (value != null
            && !value
                .startsWith(ComponentPropertiesManager.MANAGED_METHOD_PREFIX)) {
            return value;
        } else {
            throw new AttributeNotFoundException("Attribute '" + attribute
                + "' does not exists");
        }
    }

    /*
     * (non-Javadoc)
     * 
     * @see javax.management.DynamicMBean#getAttributes(java.lang.String[])
     */
    public synchronized AttributeList getAttributes(String[] attributes) {
        AttributeList list = new AttributeList();
        for (String name : attributes) {
            String value = managedBootstrap.getComponentPropertiesManager()
                .getProperties().getProperty(name);
            if (value != null
                && !value
                    .startsWith(ComponentPropertiesManager.MANAGED_METHOD_PREFIX))
                list.add(new Attribute(name, value));
        }
        return list;
    }

    /*
     * (non-Javadoc)
     * 
     * @see javax.management.DynamicMBean#setAttribute(javax.management.Attribute)
     */
    public synchronized void setAttribute(Attribute attribute)
        throws AttributeNotFoundException, InvalidAttributeValueException,
        MBeanException, ReflectionException {
        String name = attribute.getName();
        if (managedBootstrap.getComponentPropertiesManager().getProperties()
            .getProperty(name) == null) {
            throw new AttributeNotFoundException(name);
        }

        Object value = attribute.getValue();
        if (!(value instanceof String)) {
            throw new InvalidAttributeValueException(
                "Attribute value not a string: " + value);
        }

        // set the property and save the properties file
        managedBootstrap.getComponentPropertiesManager().getProperties()
            .setProperty(name, (String) value);
        try {
            save();
        } catch (IOException e) {
            throw new MBeanException(e);
        }
    }

    /*
     * (non-Javadoc)
     * 
     * @see javax.management.DynamicMBean#setAttributes(javax.management.AttributeList)
     */
    public synchronized AttributeList setAttributes(AttributeList list) {
        AttributeList result = new AttributeList();

        for (Object object : list) {
            Attribute attr = (Attribute) object;
            String name = attr.getName();
            Object value = attr.getValue();
            if (managedBootstrap.getComponentPropertiesManager()
                .getProperties().getProperty(name) != null
                && value instanceof String) {
                managedBootstrap.getComponentPropertiesManager()
                    .getProperties().setProperty(name, (String) value);
                result.add(new Attribute(name, value));
            }
        }

        try {
            save();
        } catch (IOException e) {
            return new AttributeList();
        }
        return result;
    }

    /*
     * (non-Javadoc)
     * 
     * @see javax.management.DynamicMBean#getMBeanInfo()
     */
    public synchronized MBeanInfo getMBeanInfo() {
        // get the attributes
        MBeanAttributeInfo[] attrs = getAttributesInfos();
        // get the operations
        MBeanOperationInfo[] opps = getOperationsInfos();

        // create MBeanInfo with no constructors and no notifications
        return new MBeanInfo(this.getClass().getName(),
            "Property Manager MBean", attrs, null, opps, null);
    }

    /**
     * Dynamically get the operations for the MBean. The operations are defined
     * in the properties manager with a special prefix.
     * 
     * @return
     */
    protected MBeanOperationInfo[] getOperationsInfos() {
        List<String> methods = managedBootstrap.getComponentPropertiesManager()
            .getExposedMethodNames();
        MBeanOperationInfo[] result = null;

        List<MBeanOperationInfo> operations = new ArrayList<MBeanOperationInfo>();
        Method methodList[] = managedBootstrap.getClass().getMethods();

        for (int i = 0; i < methodList.length; i++) {
            Method method = methodList[i];
            String name = method.getName();

            // add method if it has been defined by the user
            if (methods.contains(name)) {
                MBeanOperationInfo oper = new MBeanOperationInfo(
                    "Operation description", method);
                operations.add(oper);
            }
        }

        result = new MBeanOperationInfo[operations.size()];
        operations.toArray(result);

        return result;
    }

    /**
     * Dynamically get attributes for the MBean. The attributes are the ones
     * from the properties file.
     * 
     * @return
     */
    protected MBeanAttributeInfo[] getAttributesInfos() {
        // get the attributes names as sorted strings
        Set<String> attributeKeys = managedBootstrap
            .getComponentPropertiesManager().getExposedAttributeKeys();

        // build the MBeanAttributeInfo
        MBeanAttributeInfo[] attrs = new MBeanAttributeInfo[attributeKeys
            .size()];
        Iterator<String> it = attributeKeys.iterator();
        for (int i = 0; i < attrs.length; i++) {
            String name = it.next();
            attrs[i] = new MBeanAttributeInfo(name, "java.lang.String",
                "Property " + name, true, true, false);
        }
        return attrs;
    }

    /*
     * (non-Javadoc)
     * 
     * @see javax.management.DynamicMBean#invoke(java.lang.String,
     *      java.lang.Object[], java.lang.String[])
     */
    public Object invoke(String actionName, Object[] params, String[] signature)
        throws MBeanException, ReflectionException {
        Object result = null;

        final Class objClass = managedBootstrap.getClass();
        final ClassLoader loader = objClass.getClassLoader();
        final Class[] parameters = ((signature == null) ? null
            : findSignatureClasses(signature, loader));

        // Query the metadata service to get the right method
        //
        Method method = null;
        try {
            method = objClass.getMethod(actionName, parameters);
        } catch (Exception e) {
        }

        if (method == null) {
            throw new ReflectionException(
                new NoSuchMethodException(actionName),
                "The operation with name " + actionName + " could not be found");
        }

        try {
            // invoke method
            result = method.invoke(managedBootstrap, params);
        } catch (IllegalAccessException e) {
            throw new ReflectionException(e, "IllegalAccessException"
                + " occured trying to invoke operation " + actionName);
        } catch (RuntimeException e) {
            throw new RuntimeOperationsException(e, "RuntimeException"
                + " occured trying to invoke operation " + actionName);
        } catch (InvocationTargetException e) {
            throw new MBeanException(e, "Exception thrown in operation "
                + actionName);
        }
        return result;
    }

    /**
     * Find the classes of the signature
     * 
     * @param signature
     * @param loader
     * @return
     * @throws ReflectionException
     */
    private Class[] findSignatureClasses(String signature[], ClassLoader loader)
        throws ReflectionException {
        if (signature == null)
            return null;

        final int length = signature.length;
        final Class tab[] = new Class[length];

        if (length == 0)
            return tab;

        try {
            for (int i = 0; i < length; i++) {

                // try to get the primitive class
                final Class primCla = (Class) primitiveClasses
                    .get(signature[i]);
                if (primCla != null) {
                    tab[i] = primCla;
                } else {
                    // try to get the class if not primitive one
                    tab[i] = Class.forName(signature[i], false, loader);
                }
            }
        } catch (ClassNotFoundException e) {
            throw new ReflectionException(e,
                "The parameter class could not be found");
        } catch (RuntimeException e) {
            throw e;
        }
        return tab;
    }

    /**
     * Save the properties to a file
     * 
     * @throws IOException
     */
    private void save() throws IOException {
        managedBootstrap.getComponentPropertiesManager().save();
    }

About

I am a software engineer and community manager on the open source PEtALS ESB project at eBM WebSourcing.
You can get this article as PDF file on my scribd space or on my work blog.

Christophe Hamerling: PEtALS 1.2 and Axis2BC new features

Sun, 27 Jan 2008 23:50:23 +0000

PEtALS 1.2 is finally out (http://petals.objectweb.org ).
This new release introduces lot of new features and improvements like:

The MessageExchanges delivering mode has been improved and corrects a fault in the persistance of pending messages.
The NormalizedMessageRouter features new routing rules : a message is firstly addressed to local a ServiceEndpoint, secondly to a distant ServiceEndpoint, and finally to a ServiceEndpoint hosted on a stopped container.
The path of the repository where components and service assemblies are stored can be set.
The PEtALS platform is also available as a Web Application and can be deployed on standard WebServer or J2EE Server.
The petals-webadmin monitoring console features graphics that show instant message-traffic in a container.
Bugs in Ant tasks have been corrected.
...

As I have worked again on the Axis2 binding component (Axis2BC), here are some new improvements on this component:

List of available services available on URL/axis2/services
SOAP attachments support
and some bug fixes...

How does SOAP attachment works?
As simple as:

For incoming messages, all the SOAP attachments are placed as JBI ones
For outgoing messages, all the JBI attachments are placed as SOAP ones

With Axis2, two types of attachments are possible, MTOM(Message Transmission Optimization Mechanism) and SWA (SOAP With Attachments).
Both of them allows to handle large amounts of binary data. More explanations are available on the Web...
In the Axis2BC we use the MTOM approach.

Adding SOAP attachments is as simple as (code snippet from org.objectweb.petals.binding.axis2.listener.jbi.JBIListener class):

    protected OMElement createSOAPMessage(NormalizedMessage nm,
        ServiceClient client) throws XMLStreamException,
        FactoryConfigurationError, PEtALSComponentSDKException {

        // create the root element
        OMFactory fac = OMAbstractFactory.getOMFactory();
        Source body = nm.getContent();
        String content = SourceHelper.createString(body);
        XMLStreamReader parser = XMLInputFactory.newInstance()
            .createXMLStreamReader(new StringReader(content));
        StAXOMBuilder builder = new StAXOMBuilder(parser);

        OMElement document = builder.getDocumentElement();

        // add attachments if any
        if (nm.getAttachmentNames().size() > 0) {
            // enable MTOM
            client.getOptions().setProperty(
                Constants.Configuration.ENABLE_MTOM, Constants.VALUE_TRUE);

            // Add JBI attachments to the document element
            Set names = nm.getAttachmentNames();
            for (Object key : names) {
                String name = (String) key;
                DataHandler attachment = nm.getAttachment(name);
                OMText attach = fac.createOMText(attachment, true);
                document.addChild(attach);
            }
        }

        return document;
    }

And getting SOAP attachments from SOAP message (code snippet from org.objectweb.petals.binding.axis2.listener.soap.PetalsReceiver class) :

    private void copySOAPAttachmentsToJBI(MessageContext messageContext,
        NormalizedMessage nm) throws MessagingException {

        if (nm != null && messageContext != null) {
            Attachments attachments = messageContext.getAttachmentMap();
            if (attachments != null) {
                Set set = attachments.getContentIDSet();
                for (Object object : set) {
                    String id = (String) object;
                    DataHandler dh = attachments.getDataHandler(id);
                    nm.addAttachment(id, dh);
                }
            }
        }
    }

A simple test scenario
A simple scenario to test the SOAP attachments with PEtALS is described below. We use the PEtALS sample client to send data to a service that will write it into a directory. In order to use the Axis2 binding component, it is placed between the client and the targeted endpoint. The 'workflow' is:

Send data and attachments to Axis2BC provided endpoint. This endpoint provides access to an external web service.
The Axis2BC takes all the data from the incoming JBI message and put it into the SOAP message
The Axis2BC sends the SOAP message to the external web service
Axis2BC is also configured to handle external on the address previously invoked. It consumes an endpoint provided by the File Transfer binding component (FTBC)
Axis2BC handle the incoming SOAP message and put all the data (and attachments) into a new JBI message
The JBI message is sent to the FTBC endpoint
The FTBC endpoint receives the JBI message and write all the data to files
Response is sent to client...

All the needed service units are available on the PEtALS use cases section here.

This blog entry is also available at http://docs.google.com/Doc?id=dcrqrprg_27hnpbfk

Christophe Hamerling: Install configure and use a corporate maven repository and a maven proxy

Sun, 27 Jan 2008 23:50:23 +0000

Maven proxy is a nice tool but documentation available on the web is not...
This blog entry describes how to install, configure and use the maven-proxy. It also defines how to create a corporate maven repository.

Maven2 installation

Binary installation

Download the latest binary version of maven (http://maven.apache.org ) and as root:
cd /usr/share
tar zxvf maven-x.y.z-bin.tar.gz
ln -s maven-x.y.z maven2

Configuration

Add environment variables to the /etc/profile file (or in your .bashrc if you want)
M2_HOME=/usr/share/maven2
MAVEN_OPTS=-Xmx256M
PATH=$PATH:$M2_HOME/bin
export M2_HOME
export MAVEN_OPTS
export PATH

Create a deployer user

This user will be used to deploy new artifacts in maven repositories.
mkdir /home/maven
useradd -g buildauto -d /home/maven maven
passwd maven
chown -R maven:buildauto /home/maven

Create Maven2 corporate repositories

We create two repositories, one for the the artifacts that can not be installed for licence reasons and the other for the artifacts snapshots that will only be accessible directly. You have to install apache first(out of scope of this blog entry, tell your system admin to install it or ask google how to do it if you don't know how).

Directories

As root:
mkdir /var/lib/m2-repo
mkdir /var/lib/m2-repo-snapshots
chown -R maven:buildauto /var/lib/m2-repo /var/lib/m2-repo-snapshots

Create symbolic links to be abble to access these repositories with http. If apache handle directories in /var/www, simply create the links:
ln -s /var/lib/m2-repo /var/www/maven2
ln -s /var/lib/m2-repo-snapshots /var/www/maven2-snapshots

Repositories are now accessible at addresses http://repo_host/maven2 and http://repo_host/maven2_snapshots.

How to install artifacts

To install an artifact in the repository, use maven2 command:
mvn deploy:deploy-file
      -Durl=scp://repo_host:/var/lib/m2-repo
      -DrepositoryId=corpo-maven-repository
      -Dpackaging=<packaging>
      -DgroupId=<groupId>
      -DartifactId=<artifactId>
      -Dversion=<version>
      -Dfile=<file>

or this one if you already have the pom of the artifact:
mvn deploy:deploy-file
    -Durl=scp://repo_host:/var/lib/m2-repo
    -DrepositoryId=corpo-maven-repository
    -DpomFile=<pomfile>
    -Dfile=<jarfile>

You can specify the repositoryId in your maven2 configuration file to avoid entering user name and password each time (in $M2_HOME/conf/settings.xml):
<server>
   <id>corpo-maven-repository</id>
   <username>maven</username>
   <password>xxx</password>
</server>

Maven proxy installation

Download the maven-proxy standalone : http://maven-proxy.codehaus.org

Connect your maven server as root and enter these commands:
cd /usr/share
tar zxvf maven-proxy-standalone-x.y.z.tar.gz
mkdir maven-proxy
cd maven-proxy
ln -s ../maven-proxy-x.y.z/maven-proxy-standalone-x.y.z-app.jar maven-proxy-standalone-app.jar

Next we need to create the cache directory (the proxy will download the required files here)
mkdir /var/cache/maven-proxy

Copy the maven properties file in /etc/maven/maven-proxy.properties. You can download a sample of this file from the maven-proxy website.
In this file, you are going to specify the repositories you want to access through the proxy. For example:

################ GLOBAL SETTINGS
# This is where maven-proxy stores files it has downloaded
repo.local.store=/var/cache/maven-proxy
...
################ SNAPSHOT HANDLING
#If you want the proxy to look for newer snapshots, set to true
snapshot.update=false
...
################# REPOSITORIES
#This is not just a hack, it specifies the order repositories should be checked
#Note that the proxy adds a "/" which is why the urls aren't suffixed with a "/"
repo.list=local-repo,www-ibiblio-org
repo.local-repo.url=file:////var/lib/m2-repo
repo.local-repo.description=My corpo - Maven2 Repository
repo.local-repo.copy=false
repo.local-repo.hardfail=true
repo.local-repo.cache.period=0
#www.ibiblio.org
repo.www-ibiblio-org.url=http://www.ibiblio.org/maven2
repo.www-ibiblio-org.description=www.ibiblio.org
repo.www-ibiblio-org.hardfail=true
repo.www-ibiblio-org.cache.period=3600
repo.www-ibiblio-org.cache.failures=true
#other repo
...

If you want to add logs, you can modify the log4j properties file in the proxy jar file to add logs (extract and jar it again):
# Set root logger level to DEBUG
log4j.rootLogger=DEBUG,CONSOLE,R
# ConsoleAppender.
log4j.appender.CONSOLE=org.apache.log4j.ConsoleAppender
# Console PatternLayout.
log4j.appender.CONSOLE.layout=org.apache.log4j.PatternLayout
log4j.appender.CONSOLE.layout.ConversionPattern=%d [%-5p] %-20c{3} %x - %m%n
log4j.logger.org.mortbay=WARN
log4j.logger.httpclient.wire=INFO
log4j.logger.org.apache.commons.httpclient=INFO
log4j.logger.org.apache.jasper=INFO
# File appender
log4j.appender.R=org.apache.log4j.RollingFileAppender
log4j.appender.R.File=/var/log/maven-proxy.log
log4j.appender.R.MaxFileSize=100KB
# Keep one backup file
log4j.appender.R.MaxBackupIndex=1
log4j.appender.R.layout=org.apache.log4j.PatternLayout
log4j.appender.R.layout.ConversionPattern=%p %t %c - %m%n

Proxy daemon

Installing the proxy as daemon in /etc/init.d/maven-proxy
#! /bin/sh
set -e
PATH=/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin
DESC="Maven Proxy"
NAME=maven-proxy
JAVA_HOME=/home/dev/bin/java
DAEMON=$JAVA_HOME/bin/java
PIDFILE=/var/run/$NAME.pid
SCRIPTNAME=/etc/init.d/$NAME
MAVENPROXY_HOME=/usr/share/$NAME
MAVENPROXY_JAR=$MAVENPROXY_HOME/maven-proxy-standalone-app.jar
# Gracefully exit if the package has been removed.
test -r $MAVENPROXY_JAR || exit 0
# Function that starts the daemon/service.
d_start() {
# We change dir to /var/log, because Velocimacro logfile is created in the current directory
   start-stop-daemon --chdir /var/log --start --background --quiet \
                     --pidfile $PIDFILE --make-pidfile --exec $DAEMON -- -jar $MAVENPROXY_JAR \
                                                        /etc/maven-proxy/maven-proxy.properties
}
# Function that stops the daemon/service.
d_stop() {
   start-stop-daemon --stop --quiet --pidfile $PIDFILE --signal TERM
}
# Function that sends a SIGHUP to the daemon/service.
d_reload() {
   start-stop-daemon --stop --quiet --pidfile $PIDFILE --signal 1
}
case "$1" in
start)
   echo -n "Starting $DESC: $NAME"
   d_start
   echo "."
   ;;
stop)
   echo -n "Stopping $DESC: $NAME"
   d_stop
   echo "."
   ;;
restart|force-reload)
   #
   # If the "reload" option is implemented, move the "force-reload"
   # option to the "reload" entry above. If not, "force-reload" is
   # just the same as "restart".
   #
   echo -n "Restarting $DESC: $NAME"
   d_stop
   sleep 1
   d_start
   echo "."
   ;;
*)
   echo "Usage: $SCRIPTNAME {start|stop|restart|force-reload}" >&2
   exit 1
   ;;
esac
exit 0

Create the links for host startup:
ln -s ../init.d/maven-proxy /etc/rc3.d/S22maven-proxy
ln -s ../init.d/maven-proxy /etc/rc4.d/S22maven-proxy
ln -s ../init.d/maven-proxy /etc/rc5.d/S22maven-proxy

And start the proxy as root like this
/etc/init.d/maven-proxy start

Use the proxy

Now that the environment has been setted up, you can use it for your developments.

Configuration file

You have to tell maven that you want it uses the proxy. To do this, you must add the settings.xml file to your local repository (in $HOME/.m2/).
<settings>
        <profiles>
                <profile>
                        <id>default-profile</id>
                        <activation>
                                <activeByDefault>TRUE</activeByDefault>
                        </activation>
                        <repositories>
                                <repository>
                                        <id>myproject-repository-repohost</id>
                                        <name>repohost Repo</name>
                                        <url>http://192.168.1.230:9999/repository/</url>
                                        <snapshots>
                                                <enabled>TRUE</enabled>
                                        </snapshots>
                                        <releases>
                                                <enabled>TRUE</enabled>
                                        </releases>
                                </repository>
                        </repositories>
                        <pluginRepositories>
                                <pluginRepository>
                                        <id>myproject-repository-repohost</id>
                                        <name>repohost Repo</name>
                                        <url>http://192.168.1.230:9999/repository/</url>
                                        <snapshots>
                                                <enabled>TRUE</enabled>
                                        </snapshots>
                                        <releases>
                                                <enabled>TRUE</enabled>
                                        </releases>
                                </pluginRepository>
                        </pluginRepositories>
                </profile>
        </profiles>
</settings>

Now you can remove all the repositories from your pom files and let maven get artifacts from the proxy.