Hi Francisco
Andres is correct: you do need to get your SCJP cerification before you can do the SCJD.
SCJP is the prerequisite for SCJD, SCBCD, and SCWCD.
My interpretation of the certifications:
SCJP will
test your knowledge of the basic syntax of Java, and the major classes that you are likely to use every day in your programming work. A person who only has SCJP is likely good to do simple programming jobs, probably working from detailed design specifications given to them by a more senior developer in the company.
SCJD assumes you are that more senior developer. It is an assignment you must submit which tests your ability to develop an entire solution for a client based on loose specifications provided by the client. To succeed you will have to write a simple database application, create a multi user server application to access the database, and create a client GUI application to work with the data. It should be noted that the specifications the client provided are a lot more high level than what could normally be given to a junior programmer in a company.
SCWCD is for those programmers who are working primarily with
Servlets and/or
JSP. Like the SCJP exam, this is an exam, not an assignment. It covers the APIs and deployment information you will need in order to work with Servlets and JSPs.
SCBCD is for those programmers who are working primarily with EJBs. Like the SCJP exam, this is an exam, not an assignment. It covers the APIs and deployment information you will need in order to work with EJBs.
SCEA is for architechts who will be working with J2EE solutions. This is another step up from the level of knowledge required for SCJD. Normally an architecht will have quite a few years of experience with different solutions for different industries so that they have a broad depth of knowledge. This certificate has both examinations and assignments to deliver. The assignment deliverable is predominanently UML diagrams (that's how high level it is). Since there is no programming requirement, you do not need the SCJP before going for it.
As for which one to go for ... that depends on your experience and what sort of job you have or are looking for. For example if you really want to work exclusively in web design then servlets and JSP is probably your best option, and you might want to concentrate on SCWCD. If you want to show potential employers that you can write complete applications (instead of just memorizing APIs) the SCJD is probably the best bet.
If you are fresh out of university, or are looking for an entry level programming position, then you probably don't want the SCEA qualification. You may find having that will make you overqualified for programming positions, while not having enough experience to go for architecht or senior positions.
The
Sun Certified Programmer & Developer for Java 2 Study Guide (Exam 310-035 & 310-027) is an excellent book for studying for the SCJP.
Regards, Andrew