3-Tier Architecture

[Cris]

Read this article from IBM see if it is helpful
ftp://www6.software.ibm.com/software/developer/library/j-struts.pdf

I'm relatively new to Java, having spent most of my time working with
MS technologies. My company recently bought into J2EE/Unix (which we
are all very excited about), and wants to begin the process of
migrating our existing ASP/COM+ based web applications over to Java.
* Web Server: ASP pages and COM+ proxy components
* App Server: Core COM+ components containing business and DB logic
* Database Server
My question: Are EJBs the only way to duplicate this type of 3-tier
environment when you're dealing with disparate servers like this? I've
read that EJBs often tend to be overkill; however, I don't see how you
can mimic this type of architecture with just JSPs, Servlets and
standard Beans. Is there a proxy mechanism with Java, similar to COM+,
where JSPs and Servlets running on the web server can remotely call
beans on the app server?
Any help is greatly appreciated.

Thanks, both articles were very helpful; however, my question is more
related to our existing server architecture and how Java might fit.

My premature assumption on the subject is that there would be a
servlet container running on the web server to service JSP and Servlet
requests, and an EJB container running on the application server to
service business and database logic component requests from the web
server. Am I way off here? Is there an alternative to EJBs for
remotely accessing business logic components from the web server?

Forgive my ignorance; I'm fairly new to the Java world.

[bm]

You've got the big picture right. To do architectural design,
I believe you need to do a bit more studying. The three
technologies that you'd be using are EJB, JSP and servlets.
These books are very good.

EJB Design Patterns, Wiely, Feb 2002, by Floyd Marinescu, ISBN:
0-471-20831-0
Server-Based Java Programming, Manning, July 2000, by Ted Neward
- take a look at chapters 13 and 15
EJB & JSP Java on the Edge, Wiely, Oct 2001, by Lou Marco, ISBN:
0-764-54802-6

good luck

Post by Cris

Read this article from IBM see if it is helpful
ftp://www6.software.ibm.com/software/developer/library/j-struts.pdf

I'm relatively new to Java, having spent most of my time working with
MS technologies. My company recently bought into J2EE/Unix (which we
are all very excited about), and wants to begin the process of
migrating our existing ASP/COM+ based web applications over to Java.
* Web Server: ASP pages and COM+ proxy components
* App Server: Core COM+ components containing business and DB logic
* Database Server
My question: Are EJBs the only way to duplicate this type of 3-tier
environment when you're dealing with disparate servers like this? I've
read that EJBs often tend to be overkill; however, I don't see how you
can mimic this type of architecture with just JSPs, Servlets and
standard Beans. Is there a proxy mechanism with Java, similar to COM+,
where JSPs and Servlets running on the web server can remotely call
beans on the app server?
Any help is greatly appreciated.

Thanks, both articles were very helpful; however, my question is more
related to our existing server architecture and how Java might fit.
My premature assumption on the subject is that there would be a
servlet container running on the web server to service JSP and Servlet
requests, and an EJB container running on the application server to
service business and database logic component requests from the web
server. Am I way off here? Is there an alternative to EJBs for
remotely accessing business logic components from the web server?
Forgive my ignorance; I'm fairly new to the Java world.

[Michael Borgwardt]

Post by Cris
My premature assumption on the subject is that there would be a
servlet container running on the web server to service JSP and Servlet
requests, and an EJB container running on the application server to
service business and database logic component requests from the web
server. Am I way off here?

No, that's exactly the "traditional" J2EE three-tier architecture.

Post by Cris
Is there an alternative to EJBs for
remotely accessing business logic components from the web server?

There are certainly alternatives; you could simply run a custom
Java application and have the web components contact it through RMI.
It all depends on whether you think the abstractions and services
provided by the EJB framework are worth the additional complexity.