J2EE without EJB feature lists

Tomcat - Application Server
Spring 2.0 - J2EE framework
Hibernate/iBatis - ORM
JSF/Spring/WebWork - Multi-Action Web Framework
JSP - View Template
Dojo, YUI/Extension, Rico, Prototype - Rich Client Widgets
Acegi - Authentication and authorization.
SiteMesh - Web page layout and decoration framework.
Quartz - Enterprise job scheduler.
Log4j - Logging Tool
OSCache - Simple Cache and Web Cache solution
Jasper Report - Report Engine
Lucene - Search engine
ExtremeTable - JSP Table Tag Libraries.
Junit - unit test

AOP and OOP

AOP - Aspect Oriented Programming provides us the ability to interpose customer behavor before/after invocations on any object. This enable us to address crosscutting enterprise concerns that apply to multiple object.

OOP works well in general, AOP is a complementing rather than competing with OOP. For example, if we have to apply the same transactional behavior to multiple objects and methods, we need cut/paste the same code into each method. AOP give us a better way to pack such concerns into ASPECTS.

How to bind and validate in MultiActionController

In Spring framework, it provides several controller in MVC model. Personaly, I like the MultiActionController best. And I do not like SimpleFormController because it only one "onSubmit" method. For WEB page, I do not think any page just have one button, i.e: "Save" or "Update". However, SimpleFormController have strong validator ability. But I still hate lots of configure in SimpleFormController.

In Spring MultiActionController, it already provides bind method, however, this method just throws Exception when it find the invalidate error message. To catch this error, we need write a new method to override it.

The goal is to use both MultiActionController and SimpleFormController

Solution: bind and validate in MultiActionController.

In XML, you can write your MultiActionController as normal define.



Now we need bind the form and validator it.

I will use a save action as example:

First create a bindObject method in your BaseContoller (extends MultiActionController)

protected BindException bindObject(HttpServletRequest request,
   Object command, Validator validator) throws Exception {
    preBind(request, command);
    ServletRequestDataBinder binder = createBinder(request, command);
    binder.bind(request);

    BindException errors = new BindException(command,
    getCommandName(command));
    if (validator.supports(command.getClass())) {
       ValidationUtils.invokeValidator(validator, command, errors);
    }

    return errors;
}

Now in the save action, you can use this method as normal.

public ModelAndView save(HttpServletRequest request,
   HttpServletResponse response, PhoneInfo command) throws Exception {
  ModelAndView addPhoneView = new ModelAndView(LIST_VIEW, "phones",
    phones);
  addPhoneView.addObject("phoneInfo", command);

  // add validator and call bindobject to get the result
  BindException errors = super.bindObject(request, command, new PhoneInfoValidator());
  if (errors.hasErrors()) {
   addPhoneView.addAllObjects(errors.getModel());
   return addPhoneView;
  }

  // otherwise --- save this object...
  return addPhoneView;
 }

In this way, I can easy to fix my problem when I use MultiActionController. I can bind and validate any object as I like.

Hibernate ?

Hibernate is a good ORM tool. However, there also have some issue in here:

1: Criteria API, QueryObject are not as strong as sql language.

2: Lazy load or not... only define one time in XML

3: POJO ? too much use ?

RIM Blackberry and J2ME

Programming the BlackBerry With J2ME

Google Ajax

http://code.google.com/webtoolkit/

Some good tool for Ajax

prototype.js is a JavaScript library written by Sam Stephenson. This amazingly well thought and well written piece of standards-compliant code takes a lot of the burden associated with creating rich, highly interactive web pages that characterize the Web 2.0 off your back.

Spring lightweight?

Today, indeed Spring cannot be considered as “lightweight” when comparing it to other light solutions out there. this is mainly due to the vast amount of solutions it provides in almost all aspects of enterprise development. I guess “lightweight”, when taking it by its literal meaning, is somewhat inappropriate nowadays… perhaps “simple and comprehensive” is more suitable to describe Spring. But this term (I think) is not interpreted by its literal meaning. I think it’s still associated with its original meaning when it was compared with the heavy EJB containers.

Jasper and Open Reports

In the end we compared Crystal reports with Jasper Reports, and Jasper was picked. Jasper is not only free, but also is proven in the Java world, and has a lot of users. It is customizable, since its Java and open source, and has support for using Collections or Lists of Business Objects, such as those populated via Hibernate.

Once Jasper was chosen, I tested several GUI’s to help build the reports instead of editing them strictly in their native XML. JasperAssistant was found to be the best of all of them, and integrates seamlessly with Eclipse. If you are an Eclipse fan as I am, then you’ll love using JasperAssistant. It even allows you to preview the report against your database right in Eclipse.

Connecting Apache's Web Server to Multiple Instances of Tomcat

Connecting Apache's Web Server to Multiple Instances of Tomcat

http://www.linuxjournal.com/node/8561/print

Quick Reference Card

http://www.digilife.be/quickreferences/quickrefs.htm

Voice Application with J2EE

I'm convinced that J2EE lightweight container architecture is the right way to go for the majority of voice applications. However, there needs to be some tweaks in the way the UI tier utilizes it, compared to what we're used to seeing with HTML-based applications.

The standard platform architecture for Voice Application is to have 100 or so browser instances sitting on a server. The browser is not located on the client, because the client is a POT (Plain Old Telephone). The caller dials up a computer with a Dialogic or NMS card, or a SIP gateway, and the call is routed to one of the browser instances running on a server. This may be the same server that's running the app server, or it may just be on the same LAN.

So now the browser cache becomes much, much more important. If I have a few thousand phone calls coming in every hour to those 100 browsers, and they're all running the same application, the absolute worst thing I can do is a lot of dynamic page rendering. That would involve parsing the JSP into VoiceXML, and parsing the VoiceXML into runnable code, on every request.

So, component libraries like Tapestry or JSF are out. MVC frameworks like struts could be okay, as long as they're redirecting to static VoiceXML pages, instead of forwarding to JSPs.

Reusable Dialog Component (RDC) for voice application

A Reusable Dialog Component (RDC) is basically a JSP 2.0 tag, which generates VoiceXML at runtime. RDCs are part of the RDC Tag Library open source Jakarta project. Version 1.0 of the RDC Taglib was released in July 2005. The RDC Taglib projects implifies the development of server-side code in order to generate Voice XML. The RDC Taglib project includes a set of RDCs, which are a collection of JSP 2.0 tags that assist in the development of Voice applications. The RDC tags generate VoiceXML at runtime, which can execute on any VoiceXML 2.0 compliant platform. The RDC Taglib also provides a framework for implementing additional RDCs. The framework helps in orchestrating each individual RDC making sure the user data is collected, verified, and canonicalized. The collection of RDCs included in the Taglib project is made up of both, atomic and composite RDCs. Atomic RDCs collect a single piece of information from the user. For example, date, time, or zipCode are atomic RDCs. Composite RDCs collect multiple pieces of information from a user. These are usually done by using atomic RDCs or aggregating a composite with other atomic RDCs.

File transfer between .NET and J2EE

Web service seems a good solution for file transfer between .NET and J2EE platform. However, .NET environment is only support DIME format for attachment.

Direct Internet Message Encapsulation (DIME) is a new specification for sending and receiving SOAP messages along with additional attachments, like binary files, XML fragments, and even other SOAP messages, using standard transport protocols like HTTP.

Session and sessionContext

In the 2.0 version of the Servlet API, you could get hold of a HttpSessionContext object by calling getSessionContext() off an HttpSession. For example:

HttpSessionContext sessionContext = theSession.getSessionContext();

Although HttpSessionContext seems like a useful class for getting easy access to all client sessions, it appears Sun thought access to such private data was too easy. In version 2.1 of the Servlet API the HttpSessionContext class was deprecated for security reasons by Sun, with no plans for a replacement. In short, steer clear of HttpSessionContext!

print.google.com

Come here to view any book. You will be happy.

Lucene - text search engine

Apache Lucene is a high-performance, full-featured text search engine Information Retrieval (IR) library written entirely in Java. It is a technology suitable for nearly any application that requires full-text search, especially cross-platform. It lets you add indexing and searching capabilities to your applications.

Farm Pickup

Quick Solution for Existing Web Application Security

Web applications are becoming more popular software for the customer. As web application go online, security parts need to be pay attention to. Problems arise when the application can not distinguish between legitimate and illegitimate requests coming from a browser.

Through a Web browser, I touch my account information. I also touch your account information. Web application server need to validate whether I have permission to touch your account information. However, server side form date validation is really time consuming and sometimes it is nearly impossible, especially for existing web application system.

In this paper, an DES two-ways encryption/decryption are introduced in the form data validate in the web application.

Using GET/POST, some sensitive data are display in the user HTML forms or URL. For example:

http://www.yourdomain.com/accounts/editAccount.do?aId=5

Anyone can easily change the aId value and submit the changed URL to the server. One solution for this is check this user permission on the server side. Another way, we also can check whether client changed the aId, I means the aId I passed and the aId I receive.

To see whether client changes the sensitive data, the DES encrypting algorithm is used in the system. The example code is list at the end of this paper[1]:

For the above URL, I encrypted the sensitive data with the DES algorithm before passing it to the remote client. Now the client browser get the following URL:

http://www.yourdomain.com/accounts/editAccount.do?aId=SMsDoJFsmlc=5

As above example, the encrypt result is “SMsDoJFsmlc=”, the original value is “5”. When the client submit this URL to the server side, I get the encrypted aId from the request, call the decrypt(String) and get the original value.

Now suppose we change the aId as something else, this will make the decrypt result and original data value does not match. We know the client changed the value and just reject the client request.

Securing the application with SecurityFilter

Enterprise-level business applications need rigorous security regulations with varying roles; each role also requires its own set of access control lists. These roles become more important in Web-based applications, which are accessible to a wider audience. In most cases, application security must control access to each attribute that's visible on the screen.

When access to web applications needs to be restricted to certain users and groups, Tomcat provides its realm implementations. A realm groups a collection of web resources together and puts a protection mechanism around them that requires users who wish to access them to authenticate themselves, and for Tomcat to check their authorization. However, tomcat does not did enough for real application. Here comes SecurityFilter which built on the top of tomcat.

SecurityFilter is a Java Servlet Filter that mimics container managed security. It provides robust security and automatic authentication services for web applications.

Unit Testing with JUnit

JUnit provides the following features:

It provides an API that allows us to create a repeatable unit test with a clear pass/fail result.

It includes tools for running our tests and presenting the results.

It allows multiple tests to be grouped together to run in a batch.

It is very lightweight and simple to use. It takes little time to learn how it works.

It is extensible. It's the de facto unit testing framework for Java. There is a large community pf developers using it. Many free extensions are available to help us use it in specific situation. Plus, countless articles and books on the subject are avaibale.

Page Decorate with SiteMesh

SiteMesh is a web-page layout and decoration framework and web- application integration framework to aid in creating large sites consisting of many pages for which a consistent look/feel, navigation and layout scheme is required.

SiteMesh intercepts requests to any static or dynamically generated HTML page requested through the web-server, parses the page, obtains properties and data from the content and generates an appropriate final page with modifications to the original. This is based upon the well-known GangOfFour Decorator design pattern.

SiteMesh can also include entire HTML pages as a Panel within another page. This is similar to a Server-Side Include, except that the HTML document will be modified to create a visual window (using the document's Meta-data as an aid) within a page. Using this feature, Portal type web sites can be built very quickly and effectively. This is based upon the well-known GangOfFour Composite design pattern.

SiteMesh is built using Java 2 with Servlet, JSP and XML technologies. This makes it ideal for use with J2EE applications, however it can be integrated with server-side web architectures that are not Java based such as CGI (Perl/Python/C/C++/etc), PHP, Cold Fusion, etc...

SiteMesh is very extensible and is designed in a way in which it is easy to extend for custom needs.

http://www.opensymphony.com/sitemesh/

Web Application Framework Compare

Apache Struts framework

Pros:
The “Standard” - lots of Struts jobs
Lots of information and examples
HTML tag library is one of the best

Cons:
ActionForms - they’re a pain
Can’t unit test - StrutsTestCase only does integration
Project has been rumored as “dead”

Spring MVC

Pros:
Lifecyle for overriding binding, validation, etc.
Integrates with many view options seamlessly: JSP/JSTL, Tiles, Velocity, FreeMarker, Excel, XSL, PDF
Inversion of Control makes it easy to test

Cons:
Configuration intensive - lots of XML
Requires writing lots of code in JSPs
Almost too flexible - no common parent Controller

WebWork

Pros:
Simple architecture - easy to extend
Tag Library is easy to customize - backed by Velocity
Interceptors are pretty slick

Cons:
Small Community
Documentation only recently written, few examples
Client-side validation immature

Java Server Faces

Pros:
J2EE Standard - lots of demand and jobs
Fast and easy to develop with
Rich Navigation framework

Cons:
Tag soup for JSPs
Immature technology - doesn’t come with everything
No single source for implementation

Why use Hibernate?

One of the most complicated and time-consuming tasks of developing an enterprise application is writing the code to store and load data from a database at the appropriate times. Hibernate is the right tool to remedy this.

Hibernate is a powerful, ultra-high performance object/relational persistence and query service for Java. Hibernate lets you develop persistent classes following common Java idiom - including association, inheritance, polymorphism, composition, and the Java collections framework. Hibernate allows you to express queries in its own portable SQL extension (HQL), as well as in native SQL, or with Java-based Criteria and Example objects.

Hibernate allows us mapping an object model to a relational schema, keeping object model and database schema in sync. It also makes us easy persisting and retrieving an object from database.

www.hibernate.org