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jsp pages compilation and JSP engine question.  RSS feed

 
Kayla Richard
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Hi to all. I am new to the technologies of servlets and JSP. All the terminology seems to confuse me. I know that JSP pages get compiler to servlets and that JSP and servlets have the same lifecycle. What I don't understand is where the JSP engine comes in place? Is there such a thing as a servlet engine? What compiles JSP pages and servlets?
 
Cory Wilkerson
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Because JSPs are in the long run just compiled into Servlets -- you're always dealing with a Servlet -- thus, by default, you kinda have to have a Servlet engine.
Various vendors/developers provide these engines (also known as application servers) to the development community (some cost, some don't) and in doing so, promise to provide expected functionality as defined in the Java Servlet Specification.
That said...it's usually the responsibility of the application server to compile your JSP into a Servlet but there is no contract between the specification and the implementation regarding *what* compiles your JSP. It could be javac, it could be jikes, it could be any java compiler.
Hope this helps,
Cory
[ January 20, 2003: Message edited by: Cory Wilkerson ]
 
Kayla Richard
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Hi Cory.
Thank you for the explanation! I have heard of just Tomcat, but like some people here, I am confused about Tomcat and Java Web Start.
 
Cory Wilkerson
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Kayla,
Tomcat and Java Web Start are on completely opposite ends of the spectrum. Java Web Start is largely used for pushing *applications* to a clients desktop where an *application server* is responsible for servicing client requests (via a browser perhaps) to jsps and servlets.
The terminology is a bit confusing but think of an *application server* (Tomcat is one) as a piece of technolgoy that deploys web-based applications, not client applications in the traditional senese (MS Word, Excel, Eudora, etc.).
Make sense?
Cory
 
Cory Wilkerson
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It would be negligible of me not to point out that there are two distinct specifications...one for JSP and one for Servlets (both of which are usually supported by app servers). Often times application servers will say, "we're JSP 1.2 and Servlet 2.3 compliant".
Go here: http://www.jcp.org/aboutJava/communityprocess/final/jsr053/ and have a look at the JSP specification. Specifically section 8.1 which disucsses JSPs being compiled into servlets.
[ January 21, 2003: Message edited by: Cory Wilkerson ]
 
Kayla Richard
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Hi Cory.
Thank you so much for clarifying! It makes so much more sense now, yes, the terminology is very confusing from day to day there seems to be a few more acronyms to know! Thanks again, I really appreciate it.
 
It is sorta covered in the JavaRanch Style Guide.
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