NEW TRENDS IN WEB TECHNOLOGY by Casteyó

Advices for JSP – Java Server Pages

casteyo — Fri, 29 Jun 2007 17:43:14 +0000

First of all, I should explain what is the JSP technology and how JSP pages work.The JSP technology is an open, freely available specification developed by Sun Microsystems as an alternative to Microsoft’s Active Server Pages (ASP) technology, and a key component of the Java 2 Enterprise Edition (J2EE) specification. Many of the commercially available application servers support JSP technology.

How Do JSP Pages Work?

A JSP page is basically a web page with traditional HTML and bits of Java code. The file extension of a JSP page is .jsp rather than .html or .htm, which tells the server that this page requires special handling that will be accomplished by a server extension or a plug-in.

When a JSP page is called, it will be compiled (by the JSP engine) into a Java servlet. At this point the servlet is handled by the servlet engine, just like any other servlet. The servlet engine then loads the servlet class (using a class loader) and executes it to create dynamic HTML to be sent to the browser, as shown in next figure. The servlet creates any necessary object, and writes any object as a string to an output stream to the browser.

The next time the page is requested, the JSP engine executes the already-loaded servlet unless the JSP page has changed, in which case it is automatically recompiled into a servlet and executed.

In order to do good practices you should follow these advices:

Don’t overuse Java code in HTML pages
Don’t mix business logic with presentation
Use custom tags
Do not reinvent the wheel
Use the JSTL Expression Language
Use filters if necessary
Use a portable security model
Use a database for persistent information
Cache content
Use connection pooling
Cache results of database queries
Adopt the new JSP XML syntax if necessary

Example:

<%@ page language="java" contentType="text/html" %>

 
    
    The current time at the server is:
    
      Date: 
      
Month: 
      
Year: 
      
Hours: 
     
Minutes:

How to do a Circular Menu with CSS

casteyo — Wed, 20 Jun 2007 11:11:12 +0000

Look this peculiar menu fully developed in XHTML and CSS. It’s good to know the wonders that somebody can do with CSS and a little of imagination. At the moment, people agree in which one of the best ways to make flexible menus and of little weight, is to use CSS. This one is a very powerful tool and it has a great characteristic as it is to separate the code of the appearance.

At the time of approaching a design, it is important to consider certain factors like the accessibility, the facility of update, the speed of load and the compatibility. There are a lot of advantages in order to develop a menu with lists and css. Cascading Style Sheets (CSS) is a stylesheet language used to describe the presentation of a document written in a markup language. The CSS specifications are maintained by the World Wide Web Consortium (W3C).

CODE
DEMO

Configuration of Hibernate, MySQL & Eclipse

casteyo — Wed, 06 Jun 2007 21:12:04 +0000

Hi!

I’m gonna tell you how you could configure these 3 tools. Together, they provide great facilities to us to construct and to manipulate web applications. This configuration will be based on:

First of all, you have to create a new project of type Dynamic Web Project with the Eclipse environment; we are going to call it “test“. In the field “Target Runtime” we must indicate which server we are gonna use. In our case, we will use the Tomcat Apache 5.5. With the created project and a good database in the MySQL, now, we must import all the Hibernate libs into /WebContent/WEB-INF/lib folder. There is another way: you must put all the Hibernate libs into /tomcat/common/lib folder. This last one it’s better if you have to export the project in a “*.war” file.

We are ready to establish connection and mapping between the database and our project.

We are going to create the Hibernate Configuration File. This one, will contain the information to access to the database.

ROUTE: File –> New –> Other –> Hibernate –> Hibernate Configuration File

(I have to say that this configuration is right for all of the available databases. If you don’t use MySQL, you must select the correct “database dialect” and “driver class”..)

Now, we are going to create the Hibernate Console Configuration file.

ROUTE: File –> New –> Other –> Hibernate –> Hibernate Console Configuration

In addition, we are going to create the Hibernate Reverse Engineering file. This one, will allow to us to generate the source code of VO and DAO layers (VO = Value Object; DAO = Data Access Object).

ROUTE: File –> New –> Other –> Hibernate –> Hibernate Reverse Engineering

We must select the console that we had created and then clicking on the “Refresh” button, we have to be able to see the database structure. Finalize.

That’s all! Now it is everything ready to generate the source code.

ROUTE: Run –> Hibernate Code Generation –> Hibernate Code Generation

Main: We must select the console, to specify the output directory, to mark the “Reverse Engineer From JDBC connection” option and select the path of the Hibernate Reverse Engineering file in “reveng.xml”.
Exporters: we must choose to work with Java 5 and to mark:
- Domain Code
- Hibernate XML mappings
- DAO code
- Hibernate XML configuration
Run and.. source code created!

I hope this little manual of the Hibernate configuration be useful. If someone has any question, please post it.

See ya!!

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casteyo — Tue, 05 Jun 2007 18:16:52 +0000

Hello World!!

Having been inspired by many excellent blogs on the internet, I have decided to start my own blog. I will report about new trends in web technology. Some tutorials, some articles and some cheats about these new technologies which are being developed constantly.

it begins!