Many a times I have come across my friends who get this error and are clueless because this error is not something related to the programming logic neither to the server which shows this error either on accessing a servlet or a service. You have to know that this error comes when a class compiled on a newer version is being tried to run on an older JVM i.e. If you try to run a JDK 1.5 compiled class in an environment having JRE 1.4 the JRE will give you the error,
Unsupported major.minor version 49.0
This error is given because the new features introduced in the newer version of Java are not present in the older version. So you have to be careful for using such class files on older environments. For resolving this error you have to follow some simple tips as follows:
- Check you java version by running the command java - version
- Check your environment variable JAVA_HOME and the path associated with it
- Check your server installation if it was installed on an older version
- Check which path exists in the environment entries
These are the quick tips you would need to do in order to get rid of the error. Sometimes Read the rest of this entry »
Setting up SSL on Tomcat is easy and you don’t have to do much for converting your web application to work with the Https protocol. But however, the problem you would find to set up SSL is the documentation available over the web. The documentation source is available on the Apache site but it starts off good and ends with a lot of confusion. Especially I was confused on the OpenSSL part where it says to use OpenSSL.
It might be good in a production environment to use OpenSSL but if you just want to test out SSL with Tomcat alone then it is more than enough to just have your JDK and Tomcat setups. So I would make you walk through the same steps which I did while getting SSL up and running and building a secured web app within a matter of minutes.
The things which I have used to setup SSL consists of:
Even though I have used the latest version I don’t see any problems which you might face in carrying out the same set of steps for JDK 1.5 which I am about to explain. JDK comes shipped with a keytool executable which is required to generate a keystore. The keytool can be found in the earlier version of JDK too. The 3 steps which would make you to get started with setting up SSL are:
- Generating the Keystore file
- Configuring Tomcat for using the Keystore file
- Configuring your web application to work with SSL
Let’s get this party started now. Read the rest of this entry »
I had raised my concerns over using Eclipse Europa in my earlier article in which I had mentioned my discomfort in the use of Eclipse for doing a Java EE web application. For my post I got many comments from various people, some who empathized with me, some who were with me in using NetBeans, some who advised me to use ItelliJ IDEA and some who told me that I was being short sighted. All these comments are precious to me and will definitely help me in seeing in the proper direction.
But these advices will only be useful when I would reach to a proper conclusion as why people flock to a particular IDE. Furthermore, having such wonderful and varied IDE’s in the Java World it sometimes is exhausting to reach to a proper conclusion. So I believe that choosing an IDE especially for a beginner involves the main aspects like”
- GUI which is first and foremost Impression
- Ease of use in development in a RAD project
- Hot Deployment and Version Control
My first impression for an IDE involves the above 3 which are crucial. I would like to make one thing clear in my way of choosing an IDE is that, I choose IDE for RAD activities. This means that I am not fascinated by those IDE’s which involve a learning curve nor the ones which make me looking here and there baffled as to what to do next. If it would have the case for a research project then my tools definitely would have been Edit Plus and Ant.
As an average user, my intentions in using an IDE are simple. It means Read the rest of this entry »
I had created a web service client from an online web service while learning it for the first time and then had written a tutorial on creating a client with JAX-WS and JAXP. At that time I had JDK 1.5 and JWSDP 2.0 pack for web services.
I tried today working in JDK 1.6 and to my surprise I found out that it comes shipped in with web services utilities which include JAX-WS 2.0, JAXB 2.0, JAXP2.0. This means a lot of ease in the development of web services for the developer. The benefits are:
- There is no need to separately download the JWSDP 2.0 as I had mentioned in my tutorial
- There is no need to remember all the different set of libraries which are required to be included in the classpath before your program has to run.
- It eases out the development and saves your time.
Does that mean there are no Issues?
There are some. Read the rest of this entry »
Java EE (JEE) has changed its face entirely from the past. The new look of JEE is exciting and simpler. With the rise of Web 2.0 and usage of simpler and lighter mechanisms for enterprise application, JEE has come a long way, to provide the latest and the best features in the market. For the new beginner in the world of Java EE it becomes essential to know the new and exciting things which JEE provides. This article makes a brief attempt to bring forth the facts which currently ride the waves in JEE with some comparison with the earlier counterparts.
The Musketeers of Java EE
If you know Java and want to sprint in the world of Java EE (JEE), you have to face a lot of hurdles in wanting to know which kind of technologies you have learn. If you look at the most used technologies which form a standard part the JEE are: Read the rest of this entry »
Will they take a J2EE professional or a JEE professional now is the thing I am worrying about. It is obvious for a technical person to know that J2EE and JEE are one and the same except for the HR persons! How do we go about convincing them? Many people including me, still are confused about the version and the mysterious number attached to the “Java” word. Let’s try to explore what actually goes on behind these mysteries. Check this out!
The product confusion
If you are still thinking that Java 2 meant version 2 of Java then you are being duped. Java 2 means version 1.4 of Java. I am still dumbfounded as to where Java 3 and Java 4 disappeared but I guess with the success of Java 5 they were buried in debris even before they born!
I was still in bewilderment until the web started to roar about Java 6. It took me a lot of time to actually sink in the fact whether Java 5 referred to version 1.5 of Java and Java 6 referred to version 1.6 of Java. This confusion was due to the use of Java 5.0 in some places. Are Java 5.0 and version 1.5 of Java one and the same?
The fact is that Sun makes use of dual naming convention for the same thing. One naming convention if for the product and one is for the developer. The official documents mentions Read the rest of this entry »
The Servlet 3.0 specification is doing rounds of the web these days. Although people have loved to use Servlets for various purposes such as implementing business logic in case of small web applications to using it as a controller in MVC architectures, we are yet to see what power will the new specification unleash to the world of web application development.
On a brief note the Servlet 3.0 specification has been approved in the form of JSR 315 is going to be a part of Java EE 6 as mentioned by SUN:
The JCP has approved JSR 315 (ballot) starting the process that will develop Servlet 3.0. Servlet 3.0 is intended to be part of Java EE 6 together with approved JSRs like JSF 2.1 and JAX-RS 1.0 and several more yet to be launched.
The new specification suggests to bring in the feature of asynchronicity to Servlets. We still can leverage the asynchronous nature in a JEE application with the use of Ajax. Experts think that the Ajax model has a problem in its Read the rest of this entry »
