Welcome!

Eclipse Authors: Pat Romanski, Elizabeth White, Liz McMillan, David H Deans, JP Morgenthal

Related Topics: Eclipse

Eclipse: Article

Creating Web Applications with the Eclipse Web Tools Project

Using open source to develop Web applications, EJBs, and Web services

Creating Servlets and JSPs
The Model-View-Controller (MVC) paradigm requires the implementation of three loosely coupled tiers in the application:

  • Model: Business logic and domain objects of the application
  • View: Presentation, user interface
  • Controller: Something that sits between the model and view, allowing them to interact in a loosely coupled manner, meaning that the model does not have to be aware of the view, and a different view could possibly be used with the same model.

So far we have implemented only Model - domain objects and command classes. Controller will be implemented as a servlet and View will be implemented as JSPs.

Web Tools provides comprehensive wizards and editors for creating servlets and JSPs. We'll start by creating a package called "servlet" in our Eclipse project where all our servlets will reside. Next, we'll launch the wizard for creating a CreateCustomerServlet by selecting File-New-Other, and then Web-Servlet (see Figure 4).

On the screen in Figure 4, we can specify the Web Project and package where servlet should reside, and the next screen will look like Figure 5.

On this one, we can specify the optional description for the servlet, initialization parameters (that can be retrieved by the servlet in the init() method from its ServletConfig object), and URL mapping. Figure 6 shows the final screen for defining servlet.

At this point, we are presented with the capability to specify the interfaces that this servlet will implement (by default, all the servlets implement the javax.servlet.Servlet interface), and the methods that should be automatically generated when the servlet is created.

Just click on Finish and the servlet is generated. This also creates the following entry in the web.xml file:


<servlet>
<description>Create Customers
Servlet</description>
<display-name>ListCustomers</display-name>
<servlet-name>ListCustomers</servlet-name>
<servlet-class>servlet.ListCustomersServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>ListCustomers</servlet-name>
<url-pattern>/ListCustomers</url-pat-tern>
</servlet-mapping>

Another thing that must be added to web.xml is the resource reference to the datasource that has been configured in DBTest.xml:


<resource-ref>
<description>DB Connection</description>
<res-ref-name>jdbc/TestDB</res-ref-name>
<res-type>javax.sql.DataSource</res-type>
<res-auth>Container</res-auth>
</resource-ref>

This XML is necessary for the CommandExecutor datasource lookup code to work properly.

In the init() method of ListCustomers-Servlet, we will get the instance of the CommandExecutor (see Listing 8), which will retrieve the data source and cache it for future use to supply database connections. It's a good practice to cache a reference to JNDI data source, because retrieving it is a time-consuming operation.

In the doGet() method (see Listing 9), we will execute the database command and forward the list of registered customers to the JSP to display them.

In this doGet method, request attribute "customers" is set to the generic ArrayList and then RequestDispatcher object is used to forward a response to customers.jsp (see Listing 10).

Using some of the new features of J2SE 5.0 such as generics and enhanced "for" loop improves the JSP code by reducing the amount of Java code in it. Creating and editing JSP using WTP is simple. Select the Web content folder of your Web project, right-click, and select New - Other from the menu. From the dialog that appears, select Web - JSP, then specify the name of the JSP you want to create. WTP also allows you to select an existing template for your JSP to be based on. Three built-in templates are provided based on HTML, XHTML, and XML.

In a similar way, we can create other servlets and JSP pages in our application (see the source code), which is easy to import into Eclipse by using its File-Import menu. Figure 7 shows the Web site map of our simple Web application. As you can see, users initially get to index.html page from which they can perform all the other tasks, such as creating customers and orders, and listing existing customers and their orders.

Debugging Application in Eclipse with WPT
The debugging application in Tomcat involves launching the server in the debug mode. To do this, simply right-click on the Tomcat server and select "Debug." To debug some particular line of code, insert a breakpoint at the line shown in Figure 8.

The server currently running in the debug mode will be automatically selected. After a couple of clicks, the embedded browser page should appear. From now on you can debug the Web application the same way as a regular Java program.

Deploying the Application to Tomcat
Once the application has been tested, it may be ready to deploy. To deploy a Web application, first export it as a WAR file. Simply select File - Export - WAR file.

On the popup window you can check "Export source files" and "Overwrite existing file" if you wish to have your source contained within your WAR file (it may not be a good idea in production) and want to suppress a warning if the file with the same name (perhaps a previously exported version) already exists in the directory and you want to simply overwrite it.

Once the WAR file is exported, deploying it to Tomcat can be done through the Tomcat 5.0 administrative console, which in our case is located at http://localhost:8080/manager/html.

The console displays currently deployed applications and allows you to deploy new, undeploy, and reload existing applications.

Once deployed, we need to make sure that our DBTest.xml file is still there under $TOMCAT\conf\catalina\localhost with all the correct datasource definitions. If it's not, replace it with the correct one that have been saved by you before.

Now, our application is ready to run, so point your browser at http://localhost:8080/DBTest/.

Figure 9 shows what the list of orders for a registered customer will look like.

Summary
I've discussed the development, debugging, and deployment of the Web-based database application using J2SE 5.0, Eclipse Web Tools, the Tomcat application server, and the MySQL database. WTP is still in its beta release, so some of its wizards and capabilities may pose problems; however, we were able to successfully debug and deploy the Web application.

More Stories By Boris Minkin

Boris Minkin is a Senior Technical Architect of a major financial corporation. He has more than 15 years of experience working in various areas of information technology and financial services. Boris is currently pursuing his Masters degree at Stevens Institute of Technology, New Jersey. His professional interests are in the Internet technology, service-oriented architecture, enterprise application architecture, multi-platform distributed applications, and relational database design. You can contact Boris at [email protected]

Comments (15) View Comments

Share your thoughts on this story.

Add your comment
You must be signed in to add a comment. Sign-in | Register

In accordance with our Comment Policy, we encourage comments that are on topic, relevant and to-the-point. We will remove comments that include profanity, personal attacks, racial slurs, threats of violence, or other inappropriate material that violates our Terms and Conditions, and will block users who make repeated violations. We ask all readers to expect diversity of opinion and to treat one another with dignity and respect.


Most Recent Comments
Mintara 12/26/07 04:11:21 PM EST

Hello Sir,
Could you please elaborate (for e.g the classes ..I could not find the source code)what you have explained.
Thank you.

Serge Cambour 09/25/07 06:38:15 AM EDT

It would be really a very good article or a tutorial if the author had tested it himself before posting it. I don't even talk of missing details, classes, code mistakes, ets. that make you loose any wish to continue.

Keith Freeman 07/15/06 10:32:01 PM EDT

Well, this seems like a fantastic tutorial, until suddenly the "CreateCustomerServlet" description morphs into a "ListCustomersServlet". We're left to figure out how to finish the servlets ourselves (still in progress for me), since as others point out here a bunch of code is missing from the zip file download. VERY disappointing after such a strong start.

David Paules 05/24/06 04:04:22 PM EDT

Good introduction article. Unfortunately, it's not clear where the database connection file DBTest.xml should reside when running Tomcat under Eclipse. Where does this file or it's content go in the Dynamic Web project tree? Because of this, I get an error message at debug time:

javax.servlet.ServletException: Cannot create JDBC driver of class '' for connect URL 'null'

Chuck Ferrick 05/20/06 09:24:58 PM EDT

I was very interesting article, but most of the listings where not posted. I was hoping to gain some insight on how you configure Hibernate. Your article stated to look at listing 9, but listing 9 was know where to be found. I was also frustrated when I could not find the DBTest.war file on java.sys-con web site.

Good furture article and maybe next time JDJ will include all of the necesasry file listings.

Achille Komla 02/05/06 10:57:41 PM EST

Very well done. It will be good to see how the application works with hibernate.

Daniel Hillebrand 12/15/05 04:35:56 AM EST

Hi Boris,

thank you for your great tutorial! Maybe you could add a note to your article regarding running Tomcat in eclipse:

You have to put the content of DBTest.xml in the (new) file context.xml in "WebContent/META-INF". The path strings are not needed, except the "path" string.

regards, Daniel

Bill Gercken 12/09/05 09:02:38 AM EST

Soource code: For those who did not find it: the link to the source is at the top of listing 1. View link: http://res.sys-con.com/story/nov05/152270/source.html

km 12/07/05 03:41:46 PM EST

could you provide the link for the source code

Paul Mischler 12/05/05 04:39:16 PM EST

Did anyone notice that listings 3-10 aren't included in the dead-tree edition?

Corrections to the article:

For the code to work "out of the box", the Customer and Order classes need to be created in a package called "domain"

Figure 2 shows "cust_id" as a member of the Order class. However, the image of Figure 3 (and the CreateOrder class sample code) utilize "custId".

A helpful reminder that a user with permissions to access the database tables would have been helpful.

CS Cassell 12/02/05 10:01:30 AM EST

Several of the links are broken. This could be a really good article but ones needs the various links to work correctly.

José D´Andrade 12/01/05 09:11:56 AM EST

Please, think Linux. Think about Linux users when writing articles about developing whatever using:

Eclipse
Apache
Tomcat
MySQL

It is confusing to read about things that perhaps only apply to MS Windows (¨be sure to launch C:\Mysql\winmysqladmin.exe ¨) when the tools are mostly used by Linux people. And, this is not religion.

At least, write referencing both OSs.

José D´Andrade 12/01/05 09:10:40 AM EST

Please, think Linux. Think about Linux users when writing articles about developing whatever using:

Eclipse
Apache
Tomcat
MySQL

It is confusing to read about things that perhaps only apply to MS Windows (¨be sure to launch C:\Mysql\winmysqladmin.exe ¨) when the tools are mostly used by Linux people. And, this is not religion.

At least, write referencing both OSs.

Bill Dornbush 11/29/05 03:16:26 PM EST

Where is the source code for the article? I can't find any for this issue of the magazine at java.sys-con.com

@ThingsExpo Stories
Explosive growth in connected devices. Enormous amounts of data for collection and analysis. Critical use of data for split-second decision making and actionable information. All three are factors in making the Internet of Things a reality. Yet, any one factor would have an IT organization pondering its infrastructure strategy. How should your organization enhance its IT framework to enable an Internet of Things implementation? In his session at @ThingsExpo, James Kirkland, Red Hat's Chief Archi...
In his general session at 19th Cloud Expo, Manish Dixit, VP of Product and Engineering at Dice, discussed how Dice leverages data insights and tools to help both tech professionals and recruiters better understand how skills relate to each other and which skills are in high demand using interactive visualizations and salary indicator tools to maximize earning potential. Manish Dixit is VP of Product and Engineering at Dice. As the leader of the Product, Engineering and Data Sciences team at D...
Personalization has long been the holy grail of marketing. Simply stated, communicate the most relevant offer to the right person and you will increase sales. To achieve this, you must understand the individual. Consequently, digital marketers developed many ways to gather and leverage customer information to deliver targeted experiences. In his session at @ThingsExpo, Lou Casal, Founder and Principal Consultant at Practicala, discussed how the Internet of Things (IoT) has accelerated our abilit...
Organizations planning enterprise data center consolidation and modernization projects are faced with a challenging, costly reality. Requirements to deploy modern, cloud-native applications simultaneously with traditional client/server applications are almost impossible to achieve with hardware-centric enterprise infrastructure. Compute and network infrastructure are fast moving down a software-defined path, but storage has been a laggard. Until now.
Digital Transformation is much more than a buzzword. The radical shift to digital mechanisms for almost every process is evident across all industries and verticals. This is often especially true in financial services, where the legacy environment is many times unable to keep up with the rapidly shifting demands of the consumer. The constant pressure to provide complete, omnichannel delivery of customer-facing solutions to meet both regulatory and customer demands is putting enormous pressure on...
The best way to leverage your CloudEXPO | DXWorldEXPO presence as a sponsor and exhibitor is to plan your news announcements around our events. The press covering CloudEXPO | DXWorldEXPO will have access to these releases and will amplify your news announcements. More than two dozen Cloud companies either set deals at our shows or have announced their mergers and acquisitions at CloudEXPO. Product announcements during our show provide your company with the most reach through our targeted audienc...
JETRO showcased Japan Digital Transformation Pavilion at SYS-CON's 21st International Cloud Expo® at the Santa Clara Convention Center in Santa Clara, CA. The Japan External Trade Organization (JETRO) is a non-profit organization that provides business support services to companies expanding to Japan. With the support of JETRO's dedicated staff, clients can incorporate their business; receive visa, immigration, and HR support; find dedicated office space; identify local government subsidies; get...
DXWorldEXPO LLC announced today that ICC-USA, a computer systems integrator and server manufacturing company focused on developing products and product appliances, will exhibit at the 22nd International CloudEXPO | DXWorldEXPO. DXWordEXPO New York 2018, colocated with CloudEXPO New York 2018 will be held November 11-13, 2018, in New York City. ICC is a computer systems integrator and server manufacturing company focused on developing products and product appliances to meet a wide range of ...
@DevOpsSummit at Cloud Expo, taking place November 12-13 in New York City, NY, is co-located with 22nd international CloudEXPO | first international DXWorldEXPO and will feature technical sessions from a rock star conference faculty and the leading industry players in the world.
DXWorldEXPO LLC announced today that the upcoming DXWorldEXPO | CloudEXPO New York event will feature 10 companies from Poland to participate at the "Poland Digital Transformation Pavilion" on November 12-13, 2018.
22nd International Cloud Expo, taking place June 5-7, 2018, at the Javits Center in New York City, NY, and co-located with the 1st DXWorld Expo will feature technical sessions from a rock star conference faculty and the leading industry players in the world. Cloud computing is now being embraced by a majority of enterprises of all sizes. Yesterday's debate about public vs. private has transformed into the reality of hybrid cloud: a recent survey shows that 74% of enterprises have a hybrid cloud ...
In his keynote at 19th Cloud Expo, Sheng Liang, co-founder and CEO of Rancher Labs, discussed the technological advances and new business opportunities created by the rapid adoption of containers. With the success of Amazon Web Services (AWS) and various open source technologies used to build private clouds, cloud computing has become an essential component of IT strategy. However, users continue to face challenges in implementing clouds, as older technologies evolve and newer ones like Docker c...
Business professionals no longer wonder if they'll migrate to the cloud; it's now a matter of when. The cloud environment has proved to be a major force in transitioning to an agile business model that enables quick decisions and fast implementation that solidify customer relationships. And when the cloud is combined with the power of cognitive computing, it drives innovation and transformation that achieves astounding competitive advantage.
Cloud-enabled transformation has evolved from cost saving measure to business innovation strategy -- one that combines the cloud with cognitive capabilities to drive market disruption. Learn how you can achieve the insight and agility you need to gain a competitive advantage. Industry-acclaimed CTO and cloud expert, Shankar Kalyana presents. Only the most exceptional IBMers are appointed with the rare distinction of IBM Fellow, the highest technical honor in the company. Shankar has also receive...
Michael Maximilien, better known as max or Dr. Max, is a computer scientist with IBM. At IBM Research Triangle Park, he was a principal engineer for the worldwide industry point-of-sale standard: JavaPOS. At IBM Research, some highlights include pioneering research on semantic Web services, mashups, and cloud computing, and platform-as-a-service. He joined the IBM Cloud Labs in 2014 and works closely with Pivotal Inc., to help make the Cloud Found the best PaaS.
In his Opening Keynote at 21st Cloud Expo, John Considine, General Manager of IBM Cloud Infrastructure, led attendees through the exciting evolution of the cloud. He looked at this major disruption from the perspective of technology, business models, and what this means for enterprises of all sizes. John Considine is General Manager of Cloud Infrastructure Services at IBM. In that role he is responsible for leading IBM’s public cloud infrastructure including strategy, development, and offering m...
DXWorldEXPO LLC announced today that All in Mobile, a mobile app development company from Poland, will exhibit at the 22nd International CloudEXPO | DXWorldEXPO. All In Mobile is a mobile app development company from Poland. Since 2014, they maintain passion for developing mobile applications for enterprises and startups worldwide.
We are seeing a major migration of enterprises applications to the cloud. As cloud and business use of real time applications accelerate, legacy networks are no longer able to architecturally support cloud adoption and deliver the performance and security required by highly distributed enterprises. These outdated solutions have become more costly and complicated to implement, install, manage, and maintain.SD-WAN offers unlimited capabilities for accessing the benefits of the cloud and Internet. ...
Headquartered in Plainsboro, NJ, Synametrics Technologies has provided IT professionals and computer systems developers since 1997. Based on the success of their initial product offerings (WinSQL and DeltaCopy), the company continues to create and hone innovative products that help its customers get more from their computer applications, databases and infrastructure. To date, over one million users around the world have chosen Synametrics solutions to help power their accelerated business or per...
Dion Hinchcliffe is an internationally recognized digital expert, bestselling book author, frequent keynote speaker, analyst, futurist, and transformation expert based in Washington, DC. He is currently Chief Strategy Officer at the industry-leading digital strategy and online community solutions firm, 7Summits.