'The Late Adopter's Guide' is a short composition to help developers who are busy supporting legacy (e.g. JDK 1.4, EJB 2.1, Struts 1.x, JSP) Java technologies (like me!) that they have little time to try out newer stuff or there were technical limitations trying to introduce newer stuff into existing systems. But now you are itching to learn that one technology you've been craving all along.
This post will focus on JSF (Java Server Faces).
JSF isn't a new technology but was saddled with limited functionality in its early iterations. If it were not a part of the Java EE standard, it wouldn't have survived till today. Now at version 2.1, JSF is mature and now's a good time to pick it up.
There were lots of stuff happening since version 1 till 2.1. This guide will allow you to skip the noise and brings you to the goodness of 2.1 without getting bogged down by legacy issues e.g. adding Facelets support to JSF 1.x.
My recommendation of certain APIs over others is based on personal experience, so feel free to try out others if you are compelled to do so.
So, here are the pointers to smooth JSF-ing:
1) Use JSF 2.1 (and above)
Do not use a lower version of JSF. This will save you lots of heartache. If your system does not meet the minimal requirements for JSF 2.1, then it's better to stick with existing frameworks you're currently using (if it gets the job done, why not?).
JSF 2.1 requires Java 1.5 or later, JSP 2.1, JSTL 1.2 and a Java Servlet 2.5 implementation. Tomcat 6 or 7 is recommended.
Use the latest JSF 2.1 with all its new features i.e. Facelets, parameterized methods in EL
2) Use the Mojarra JSF distribution
It's the RI (reference implementation) and stable. You can try Apache MyFaces but the real gem of JSF is not really the framework, but the component libraries.
3) Use Facelets
Forget about JSPs, even though you'll be tempted to leverage on your existing JSP skills and tools e.g. JSTL, taglibs. Facelets are just XHTML pages which is quite similar to JSPs, except that it won't allow you to embed Java code using scriptlet tags (<% %>), and you'll have to learn the new EL (expression language) syntax which is not JSTL but is almost functionally the same. However, if you have JSTL or OGNL background, then EL will be a piece of cake for you.
Facelets also has in-build support for page templating, so there's no need for 3rd-party page templating libraries like SiteMesh.
4) Don't worry about JBoss EL
There was a buzz about JBoss EL, where it lets you pass parameters to a managed bean's methods (Why was it not included in earlier JSF version? I have no idea). These feature has been incorporated into JSF 2.1
5) Manage JSF Managed Beans via Spring
If you are an ardent Spring user, then it's recommended to use Spring to manage JSF's managed beans' dependencies. JSF's dependency injection framework is decent but you'll definitely miss Spring's more powerful and sophisticated features.
Or you can go CDI if you want to go standard Java EE.
6) Use a component library
The best thing about JSF is there are so many component libraries to choose from. RichFaces, OpenFaces, IceFaces, you name it.
But if you want to skip R&D and dive right into the action, I recommend to start with PrimeFaces. But chances are that if you are comfortable with a particular library, you won't be inclined to switch. Caveat emptor?
If you don't want to use a component library, you'll be missing most of the goodness that JSF has to offer.
You can use multiple component libraries in a single web application, but it would be messy and incur unnecessary overhead in memory.
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