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Q: A Solution for Multi-Identity Multi-Home HTTP Servers ?

From: David Blustein <David.Blustein@csn.net>
Date: Fri, 29 Sep 1995 15:32:52 +0000
Message-Id: <199509292131.PAA01889@lynx.csn.net>
To: HTTP-WG Mailing List <http-wg%cuckoo.hpl.hp.com@hplb.hpl.hp.com>
I've browsed the web pages at www.w3.org. searching for the answer
to this question, but found no definitive answer.  If this has already
been solved, please let me know and drop this message in the bit 
bucket :)


A Solution for Multi-Identity Multi-Home HTTP Servers ?

A single HTTP server can currently process HTTP requests for multiple
FQDNs by aliasing them to the same IP via DNS.  Unfortunately, the HTTP
server doesn't know which request belongs to which FQDN.  However,using
multiple IP addresses, one for each DNS alias, does allow the server to
match requests to the corresponding FQDN.  Why can't a small addition 
to HTTP allow a simpler way of processing multiple FQDNs on a single 
HTTP server?

For example:

HTTP clients could send the complete URL request with the request 
data (i.e., include the FQDN used in forming the oringinal URL).

HTTP servers could then take the FQDN and in conjunction with a flat 
table lookup go to an arbitrary starting directory based on the FQDN.

In the DNS on a single host running a single HTTP server we have:

www.my.com.     A
www.other.com.  CNAME      www.my.com.
www.your.com.   CNAME      www.my.com.

In a flat file we have:

www.my.com.      /var/pub/www/
www.other.com.   ~othercom/webpages/
www.your.com.    ~yc/public_html/

Where www.my.com. is the base identity of the host in question and 
all directories given follow existing security restrictions for the host.

A request can then be handled as follows:

A HTTP client get a request for the

The HTTP client resolves the FQDN www.other.com. as IP address

The HTTP client connect to the HTTP server at that IP address.

In the data portion of the request the HTTP client send the FQDN 
given in the URL.

The HTTP server receives the FQDN and performs a flat table lookup 
for www.other.com. and finds the home directory for that name.

The HTTP server goes to directory ~othercom/webpages/announcements 
and processes the remainder of the request as usual.

Some Advantages:

We can use a single IP address for multiple identities instead of one
for every identity we want to support on a given host.

To create a new identity we need only add a CNAME record to the DNS
and a one-line entry in a flat file for performing lookups.

A separate home directory can be defined for each separate identity.

We add functionaly to HTTP at a small price.


We have to update HTTP servers and HTTP clients in that order.

Please send comments to:
David T. Blustein
Network Integration Design, Inc.

E-Mail: <dtb@NID.COM.>
WWW: <http://www.csn.net./~dtb/>
Received on Friday, 29 September 1995 14:34:05 UTC

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