WAR (file format) - Wikipedia_djvu.txt

WIKIPEDIA 


WAR (file format) 


In software engineering, a WAR file (Web 


Application Resource!!! or Web application 
ARchivel2!) is a file used to distribute a 
collection of JAR-files, JavaServer Pages, 


Java Servlets, Java classes, XML files, tag 


libraries, static web pages (HTML and 
related files) and other resources that 


together constitute a web application. 


Content and Web ARchive 


structure Filename  .war 
extension 
Internet applicat 
A WAR file may be media type archive 
the same way as a number (standard Z 
JAR file in order to file) 
allow others to Developed by Sun 
Micro 
determine where the 
Container for JSP 
source code came aia 
from. Servle 
Extended from JAR 


There are special 
files and directories within a WAR file: 


e The /WEB-INF directory in the WAR file 
contains a file named web.xml which 
defines the structure of the web 
application. If the web application is 
only serving JSP files, the web.xml file is 
not strictly necessary. If the web 
application uses servlets, then the 
servlet container uses web.xml to 
ascertain to which servlet a URL request 
will be routed. The web.xml file is also 
used to define context variables which 
can be referenced within the servlets 
and it is used to define environmental 
dependencies which the deployer is 
expected to set up. An example of this is 
a dependency on a mail session used to 


send email. The servlet container is 
responsible for providing this service. 


Advantages of WAR files 


e Easy testing and deployment of web 
applications 

e Easy identification of the version of the 
deployed application 

e All Java EE containers support WAR 
files 

e MVC structure supports WAR files. 

Assuming production environments do not 


promote a fix without sufficient testing 
prior to deployment, a WAR file has a 


distinct advantage when properties files 
are used to identify environment specific 
variables. For example, an LDAP server in 
a testing environment may be something 
like 

ldaps://testauth.example.com:6 
36 . The LDAP server in a production 
environment is 

ldaps://auth.example.com: 636 . 
An external properties file would define the 
link with some thing like: 


LINKED_PAGE=l1daps://testaut 


h.example.com: 636 


The source code reads the property file to 
determine the target LDAP server. In this 
way, developers can be certain that the 
WAR file tested and verified is exactly the 
same as that which is being promoted to 
production. 


Disadvantages of WAR files 


Some consider web deployment using 
WAR files to be disadvantageous when 
minor changes to source code are required 
for dynamic environments. Each change to 
source code must be repackaged and 
deployed in development.!2! This does not 


require stopping the web server if 
configured for runtime deployment.!4! 


Example 


The following sample web.xmI! file 
demonstrates the declaration and 


association of a servlet: 


“(xi wersion=” 10° 
enoodiang="UlE=o" 7S 
<!DOCTYPE web-app 

PUBLIC: “*=77/5un 
Microsystems, Inc.//DID Web 
ADDIICatLioOn 2.4/7 il” 


 Dttes J /lave<eum.com/ |26e,; ca 
LOSs/web=a2pp.4-4.0La" > 


<web-app> 
<servlet> 

<servliet- 
name>HelloServlet</servlet- 
name> 

<servliet- 
class>mypackage.HelloServle 
t</servlet-class> 


</servlet> 


<servlet-mapping> 
<serviet- 


name>HelloServlet</servlet- 


name> 

<url- 
pattern>/HelloServlet</url- 
pattern> 


</servlet-mapping> 


<resource-ref> 
<description> 
Resource 
reference to a factory for 
jJavax.mail.Session 
instances that 
may be used for sending 
electronic mail messages, 
preconfigured 


to connect to the 


appropriate oOMTP server. 

</description> 

<res-ref- 
name>mail/Session</res-ref- 
name> 

<res- 
type>javax.mail.Session</re 
s-type> 

<res- 
auth>Container</res-auth> 

</resource-ref> 


</web-app> 


The /WEB-INF/classes_ directory is 


on the ClassLoader's classpath. (The 


classpath consists of a list of locations 


from which .class_ files can be loaded 
and executed by the JVM.) The /WEB- 
INF/classes_ directory contains the 
classes associated with the web 
application itself. 


Any JAR files placed inthe /WEB- 
INF/1ib directory will also be placed on 


the ClassLoader'ss classpath. 


See also 


e EAR (file format) 
e JAR (file format) 


References 


1. Crossley, Allistair. ‘Apache Tomcat 8 
(8.0.44) - Tomcat Web Application 
Deployment" (https://tomcat.apache.org/to 
mcat-8.0-doc/deployer-howto.html) . 
Apache Software Foundation. Retrieved 
2017-06-27. 


2. Hunter, Jason (1999-10-15). "What's New in 
Java Servlet API 2.2?" (https://www.infowor 
Id.com/article/2076518/what-s-new-in-java 
-servlet-api-2-2-.html) . JavaWorld. 
Retrieved 2020-11-08. 

3. "Web Application Lifecycle" (https://docs.or 


acle.com/javaee/6/tutorial/doc/bnadu.htm 
|) . The Java EE 6 Tutorial. Oracle. 


4. "Deploying on a running Tomcat server" (htt 
ps://tomcat.apache.org/tomcat-6.0-doc/de 
ployer-howto.html#Deploying_on_a_running 
_Tomcat_server) . Apache Software 


Foundation. 


External links 


e Packaging Web Archives (https://eclipse 
-ee4j.github.io/jakartaee-tutorial/packag 
ing003.htmlI#BCGHAHGD) Archived (htt 
ps://web.archive.org/web/20201 106084 
953/https://eclipse-ee4j.github.io/jakart 
aee-tutorial/packaging003.htmlI#BCGHA 
HGD) 2020-11-06 at the Wayback 
Machine (The Jakarta EE 8 Tutorial) 


e JSR 154: JavalM Servlet 2.4 
Specification (https://jcp.org/en/jsr/det 
ail?id=154) 


Retrieved from 


title=WAR_(file_format)&oldid=1176103995" 


WIKIPEDIA 
This page was last edited on 19 September 2023, 


at 14:08 (UTC). = 
Content is available under CC BY-SA 4.0 unless 
otherwise noted.