No form parameters are passed when submitting a form

The problem once identified was so stupid and obvious that for while I felt bad. I should have found it very quickly. Anyway, so what was happening is, I created a login for my new web application and after integrating with Spring security I was not able to login. I changed the log level of Spring security package to TRACE and then found that username and password are passed as empty strings.
Then I checked the request sent from browser and noticed that browser is not sending the params with the request.
Below is my html code of the login form:



I spent some time to figure out what is happening but it was already past midnight so I left it like that and slept.
In morning I looked into the code again and very quickly noticed that the input elements in the html does not have "name" attribute. Ooops !!! Very stupid mistake done by someone who has created many web applications.

But it shows that sometimes simple mistakes like this are hard to find.

~Manish

Enable Conversation using Session attributes in Spring

In a Spring framework project we use form objects saved as session attributes to achieve a conversational style of creating and editing business objects.
But recently I realized that this functionality does not work if you have more than one tab open in the same browser. Reason is simple, if you are editing an object in first tab and start editing another object in second tab then the session attributes gets replaced by the second object. And now if you save first object then actually the second object will be updated with the information of first object.

This happens because spring saves the objects into session with same attribute name, so the object saved later will replace any other object. And when POST request is made from already loaded UI then it will always update the object which was saved later.

There is a very easy solution to the above issue. We can extend the class "DefaultSessionAttributeStore" and override just one method,  which is "getAttributeNameInSession(WebRequest request, String attributeName)", as shown below:

  
@Override
  protected String getAttributeNameInSession(WebRequest request, String attributeName) {
    String cid = request.getParameter(attributeName + "_cid") == null ? ""
        + request.getAttribute(attributeName + "_cid", WebRequest.SCOPE_REQUEST) : request.getParameter(attributeName
        + "_cid");
    if (cid != null || !"".equals(cid)) {
      return super.getAttributeNameInSession(request, attributeName + "_" + cid);
    }
    return super.getAttributeNameInSession(request, attributeName);
  }

This class should also implement interface "InitializingBean" and override method "afterPropertiesSet()" as shown below:

  @Override
  public void afterPropertiesSet() throws Exception {
    annotationMethodHandlerAdapter.setSessionAttributeStore(this);
  }

This will make sure that this custom session attribute store is added to the annotation handler adaptor.

Now when ever you save the form into model map, make sure that you add another attribute with name "{your form name}_cid" and value as the unique id for the form.
And from the JSP add a hidden input which will be sent along with the POST request.

<input name="{your form name}_cid" type="hidden" value="<c:out value='${your form unique id}'/>" />

Thats it! You can now edit different entities in different tabs under same browser session.

Please add comment if you have any question.

Thanks,
Manish

Resolving "Could not resolve view with name ... in servlet with name ..."

I was creating a web application using Spring with Apache Tiles, and my application did not work after I enabled the TilesView and TilesConfigurer. My configuration was as shown below:



I was getting below error.
SEVERE: Servlet.service() for servlet [onecode] in context with path [/onecode] threw exception [Could not resolve view with name 'search' in servlet with name 'onecode'] with root cause
javax.servlet.ServletException: Could not resolve view with name 'search' in servlet with name 'onecode'
    at org.springframework.web.servlet.DispatcherServlet.render(DispatcherServlet.java:1200)
    at org.springframework.web.servlet.DispatcherServlet.processDispatchResult(DispatcherServlet.java:1005)
    at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:952)
    at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:870)
    at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:961)
    at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:852)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:621)
    at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:837)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:728)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:305)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:222)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:123)
    at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:472)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:171)
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:99)
    at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:936)
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:407)
    at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1004)
    at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:589)
    at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:310)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
    at java.lang.Thread.run(Thread.java:744)

From the error it seems the control is not even reached to Tiles because I did not see any Tiles class in the stack trace. I checked all the configuration files multiple times and everything looked just fine.
After spending some time struggling to find the issue, I noticed that I had a typo in the "tiles-def.xml" file. One of the definition was extending a base definition and there I typed the incorrect name of the extended definition. The issue got resolved as soon as I corrected the base definition.

~Manish

Incorrect position of form object in spring controller

Today I wasted some time to find out why my spring controller method errors out even before entering into the method.
My failing method is:


But I knew I am doing things right. I debugged  the application and then searched on net but could find why it is failing. Suddenly I thought is it the position of the "User" model attribute which is causing the issue. Then I changed the method as below:


Notice that I moved the method argument "@ModelAttribute @Valid User user" from first to second last. And Voila!! it worked.

FYI: I am using Spring 3.2.

Learning MongoDB

I spent sometime to learn some basic stuff about MongoDB. I started searching internet and found some very helpful links.
Try the MongoDB online (interactive tutorial): http://try.mongodb.org/
Little MongoDB book (PDF) : http://openmymind.net/mongodb.pdf

After going through above links I got some confidence and I downloaded the MongoDB from http://www.mongodb.org/downloads .  Installing the db was very simple and within minutes I was having mongo up and running on my Macbook.

Then I thought of creating a sample spring application to learn spring integration with mongo. I followed the documentation at http://docs.spring.io/autorepo/docs/spring-data-mongodb/1.4.3.RELEASE/reference/html/index.html.

I created an application which fetches all users from the database. The code for the sample application is available at https://github.com/itsmanishagarwal/SpringMongoDb.

Anybody can download the code and use as per their need.

~Manish

How to quickly setup ActiveMQ broker, publisher and subscriber

Last week I was working on an issue related to ActiveMQ messaging. During my debugging the most painful part was to start the entire application and then execute the test scenario just to test some functionality or feature in ActiveMQ. After spending some time I realized that to speed up my debugging and anaysis I have to create a separate application/program which I can start and stop quickly after making changes. So, I created two programs:
ActiveMQPublisherTest: This program start the ActiveMQ broker and then push messages into a queue.
ActiveMQSubscriberTest: This program listens to the ActiveMQ broker started by "ActiveMQPublisherTest" and receives the event published by it.

I have published the entire source code on GitHub at: https://github.com/itsmanishagarwal/ActiveMQTest

To use these programs you just need to change the XML files to point to your database.

Any suggestions or feedback is welcome.

~Manish

Override the properties in wro.properties

Sometimes there is a need to override some properties on local environment to facilitate faster development. If you have implemented the wro4j using spring then it is very easy to override any property in wro.properties file.

Just replace the  wroProperties bean in the applicationContext.xml with below code and spring will look for the property file from other locations.

    <bean id="wroProperties"
        class="org.springframework.beans.factory.config.PropertiesFactoryBean">
        <property name="ignoreResourceNotFound" value="true"></property>
        <property name="locations">
            <list>
                <value>file:${catalina.home}/conf/wro.properties</value>
                <value>file:${catalina.home}/wro.properties</value>
                <value>file:${user.home}/wro.properties</value>
            </list>
        </property>
    </bean>

Property "<property name="ignoreResourceNotFound" value="true"></property>" ensures that bean creation will not fail even if the wro.properties file is missing. And property file at location mentioned latter overrides the property file before it. Means, if there is a property file at user home then it will override all the property file at other locations.

In my development setup I have placed a wro.properties i user home and set the managerfactoryclassname property to my custom class which disables the minimization. 
(To disable minimization check my blog at: http://msquare-tech.blogspot.in/2012/10/disable-minimizing-resources-when-using.html)

~Manish