Troubleshooting
Problem
web.xml description and functionality
Symptom
PART: Distributed Order Management 7.3 Platform
DATABASE: Oracle -
9.2.0.4
WEB SERVER: WebLogic - 8.1 SP3
WEB BROWSER: Internet Explorer -
6.0 sp1
Problem
Description:
--------------------------------
This solution is
created to describe the components, functionality and impact of web.xml on
Yantra.
Cause
Resolving The Problem
Brief overview of Web
Application:
-------------------------------------------------------
A
Web Application contains an application's resources, such as servlets,
JavaServer Pages (JSP), JSP tag libraries, and static resources such as HTML
pages and image files. A Web Application can also define links to resources
outside of the application such as Enterprise JavaBeans (EJBs).
In this
case, web application is Yantra (73HF14) and application server is Weblogic 8.1
SP3
What is web.xml?
-----------------------------
Web.xml is
a standard J2EE deployment descriptor that is used to deploy a web application
on an application server. In this we register servlets, define servlet
initialization parameters, register JSP tag libraries, define security
constraints, and define other Web Application parameters.
Components of
web.xml:
---------------------------------------
<context-param> -
This element declares servlet context initialization parameters for a Web
Application. These are parameters that you define and are available throughout
your Web application.
<listener> - This element defines an application
listener. A listener class responds to the web application
events.
<servlet> - This element defines servlet used in the
application. If a jsp-file is specified and the <load-on-startup> element is
present, then the JSP is precompiled and loaded when WebLogic Server starts in
the order of value given in <load-on-startup>.
<servlet-mapping> - After
all the servlets are defined, they need to be mapped to the URL pattern. The
portion of the URL after the http://host:port + WebAppName is compared to the
<url-pattern> by WebLogic Server. If the patterns match, the servlet mapped in
this element will be called.
<session-config> - The number of minutes
after which sessions in this Web Application expire. The value set in this
element overrides the value set in the TimeoutSecs parameter of the
<session-descriptor> element in the WebLogic-specific deployment descriptor
weblogic.xml
<mime-mapping> - Defines a mapping between an extension and
a mime type. (MIME = Multipurpose Internet Mail
Extensions)
<welcome-file-list> - This element contains an ordered list
of welcome-file.
elements.
Functionality:
----------------------
Once all
the components are defined, the application is deployed on to the server. The
configuration is taken up from the descriptor files, web.xml and weblogic.xml.
For rest of the configuration that are not defined in the descriptor files
default values are used.
Impact on the
system:
---------------------------------
The definitions provided in
web.xml directly impact the web application. For example, if we miss out any
servlet name then that servlet is not loaded when it is called.
Ex: If
we remove WMSPackStrategyAPI servlet from web.xml and deploy Yantra on Weblogic
server, FileNotFound Exception will appear in the configurator when we try to
view Pack Planning details. (Applications -> Warehouse Management -> Packing ->
Pack Planning)
General
findings:
---------------------------
-- To apply any changes done in
web.xml, we have to redeploy Yantra on the Weblogic server.
-- When we apply
the changes done from the Weblogic Console, Yantra is automatically redeployed
and the changes are reflected back to the descriptor files.
-- Weblogic
picks up the descriptors files placed under <YFS_HOME>/webpages/WEB-INF folder.
Historical Number
PRI49601
Product Synonym
[<p><b>]Fact[</b><p>];
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Document Information
Modified date:
16 June 2018
UID
swg21546568