Virtual hosts

A virtual host is a configuration enabling a single host machine to resemble multiple host machines. Resources associated with one virtual host cannot share data with resources associated with another virtual host, even if the virtual hosts share the same physical machine.

Each virtual host has a logical name and a list of one or more DNS aliases by which it is known. A DNS alias is the TCP/IP host name and port number used to request the servlet, for example yourHostName:80. When no port number is specified, 80 is assumed.

When a servlet request is made, the server name and port number entered into the browser are compared to a list of all known aliases in an effort to locate the correct virtual host and serve the servlet. If no match is found, an error is returned to the browser. Use unique name as described in Warning: no string named [ccws_vhost_alias] found..

If more than one match is found and the matches are not for the same Application Server, an error is returned if the application is not on the Application Server with the first matching entry.

An Application Server provides a default virtual host with some common aliases, such as the machine IP address, short host name, and fully qualified host name. The alias comprises the first part of the path for accessing a resource such as a servlet. For example, it is localhost:80 in the request http://localhost:80/myServlet.

A virtual host is not associated with a particular node (machine). It is a configuration, rather than a "live object," explaining why you can create it, but cannot start or stop it. For many users, creating virtual hosts is unnecessary because the default_host is provided.

Adding a local host to the virtual hosts adds the host name and IP address of the local host machine to the alias table. This allows a remote user to access the administrative console.


Related concepts
Why and when to use virtual hosting
The default virtual host (default_host)
How requests map to virtual host aliases
Related tasks
Configuring virtual hosts



Searchable topic ID:   crun_vhost
Last updated: Jun 21, 2007 4:55:42 PM CDT    WebSphere Application Server Network Deployment, Version 5.0.2
http://publib.boulder.ibm.com/infocenter/wasinfo/index.jsp?topic=/com.ibm.websphere.nd.doc/info/ae/ae/ccws_vhost.html

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