No, its not necessary to use IHS with WAS. You can have IIS or APACHE configured to do the same things. But if you do not want any webserver at all , then you better be having a standalone JVM and not a cluster JVM.
Secondly , I see that the that you have given context uri as -
http://localhost/desktop/contextmap.jsp which is incorrect, this may work when you are trying to directly access it on your desktop.
But in JVM you need to give relative path and not the absolute path.
E.g
<context-param>
<param-name>javax.faces.CONFIG_FILES</param-name>
<param-value>/WEB-INF/faces-config.xml</param-value>
</context-param>
So, if you app is installed and file is located as -
C:\IBM\SDP\runtimes\base_v7\profiles\AppSrv01\installedApps\RRNode01Cell\Test.ear\Test.war\WEB-INF\contextmap.jsp
web.xml should be --- <param-value>/WEB-INF/contextmap.jsp</param-value>
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Again I might be in-accurate as not a developer , but I hope you get what I wanted to convey.
Regards,
Harneet