Whats the big deal about Seam

Recently we had this discussion about whats the big deal about Seam. If one looks at the cricket game the seam on the ball decides a lot about the game - particularly in bowler friendly conditions. However the seam that we were discussing was not related to cricket. It was related to the web framework called Seam (http://www.seamframework.org/). Its a relatively new framework on the horizon. This blog is about whats the big deal about this Seam!

To understand whats the big deal one needs to have a background about some of the related J2EE technologies particularly Java Server Faces (JSF) and Enterprise Java Beans 3.0 (EJBs). These two are mature technologies now and enough developers have tried them out in various contexts. There are a few drawbacks of JSF that have been reported so far.

• The most important one is that JSF requires an XML configuration file to manage beans in the backend and the navigation rules. The integration with the EJBs in the backend is not very smooth.
• People consider JSF "less" object oriented and more of XML tags. The string expressions here are not type safe.
• JSF makes it hard to unit test, debug by stepping through. Further more the generated HTML is very verbose.
• Templates and Custom components are hard to use.

Over all the general consensus was that for JSF is hard for the average developer to use with the EJBs (version 3) in the backend. Even though these frameworks are complementary they are built independent of the other. One has to do too much of a glue code. Seam was introduced with these problems in mind - the missing framework in between.

So lets see whats the big deal about Seam...

• Seam is annotations based as opposed to using XML for configuration. What this means is that the developer can put the meta data related to a particular class right next to it instead of in a configuration file else where.
• Further annotated objects become the standard way for a developer to write all code - simpilfies the application.
• A more important concept Seam brings to the table is that of a context for every object (called conversations). In the earlier world the developer had to fend for herself when it comes to storing and retrieving information related to sessions. In the Seam world, one can annotate an object about the scope of its life and the framework takes care of storing and making the object available as needed. The framework understands that applications are stateful and helps to automatically manage that.
• Seam achieves the contextual information movement using dependency bijection. This makes it possible for you to use two different tabs on the same browser instance to buy a CD and a book at the same time on your favourite website. Now that sounds powerful.
• Under the hood Seam brings in a new way of looking at web applications. It shakes up the conditioning that we developers have been subjected to in terms of HTTP sessions.
• Another good thing that Seam has done is that it has brought about the best of breed libraries (for example iText for PDF document generation) for various aspects.

Overall Seam tries to bring in Rails kind of developer productivity to Java while still providing the raw power. Its not there yet, but its trying! Are there any disadvantages to Seam - well its a bit early to say but here are a couple of thoughts I have.

• At first because its a different programming model, one needs to unlearn some of the stuff from the past and that is hard. So it feels that the learning curve for Seam is high.
• Secondly since Seam is more annotations, one needs to get the configurations right early on. Any change in configurations means a re-compile (whereas in the XML world it might have been an application reload).

As we discuss this, tons of developers are trying out Seam. Lets hope that we come to hear more short comings of Seam and the community fixes them. Eventually the roadmap is that Seam is being proposed as Web Beans (JSR 299) specification in the next version of Java Enterprise Edition. One would wait and watch.