Tuesday, June 26, 2007

J2EE-self-study

Multi Tiered J2ee architecture

1.client tier

2.webtier

3.business tier

4.EIS tier (enterprise information system) like DB ,ERP., etc.,


The client tier comprosises of programs executed on the client side.

The html pages, xml pages,applets etc are executed on the cleint browser..

web clients(html xml etc) are generally markup language based pages.

application clients are applets( small application clients embedded
in a markup page like html ) and other GUI based..

The application clients directly communicate withthe business tieror
via web tier(http connections)

coming to web clients and applets,
who gives the browser the required programs?

none other than web tier components..

web components are jsp,servlets .. (J2ee specification defines these as
j2ee components)

But the components executed in the client side
are given by the web components..s
so the webcomponents' code has embedded code for giving the client
the required client components like html ,applet etc.,

the embedded client components are not treated as j2ee components..

eg:
You open a website home page from your browser,
the displayed html page or applet is actually delivered by a web component
and executed by the browser..,


application client:

eg: Toad is a tool which requires oracle client..,
and the tool is meant to directly connect with EIS and
manipulate the data bases..
which means the application cleints are basically used
by the application developers or testers or mainteners..

the web clients are generally used by the end-user (customer)..

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