PMC e-mail id: 4113
>From: "Gregg Williams" <GREGGW @
real3 .
realtime .
co .
za>
>Date: Wed, 15 Nov 1995 08:07:21 GMT+2
>Subject: Thats How Netscape does it!
>
>Hi All,
>
>When your web browser connects to home.netscape.com, you actually
>get home1.netscape.com or home2.netscape.com or home3...
I was also intrigued to learn that netscape uses 5 or 6 ftp servers to
load-balance the heavy access.
Anyway, regarding the http access, my guess is as follows.
Set up a machine as home.netscape.com.
Now, prepare other machines as backup.
When a user client accesses home.netscape.com's home page, issue a
response saying that the server has moved at the HTTP level. There is
this feature in HTTP spec for telling the client that the server has
moved. This, as I understand, is handled more or less transparently
by modern web clients. (Certainly by netscape's browser, I think.)
Then, the browser automatically accesses the new host and obtains the
home page from there. [Well, after writing up to this point. I wonder
what happens if there is a cycle of reference. Can this be a cause of
denial of service attack!?!?]
The front end machine is hit for every new client access, but this
host tells the client that the server has moved to a new location, and
the subsequent accesses from the same client will be done to one of
the chosen hosts. Here is the relevant excerpt from the HTTP spec.
=== quote ====
6.3.2 Redirection 3xx
This class of status codes indicates that further action needs to
be taken by the client in order to fulfill the request. The action
required can normally be carried out by the client without
interaction with the user, but it is strongly recommended that this
only takes place if the method used in the request is either GET or
HEAD.
301 Moved Permanently
o Following: GET, HEAD, POST, PUT
o Required metainformation: URI-header, Location
The object requested has been assigned a new permanent URI, and any
future references to this object must be done using the returned
URI. Clients with link editing capabilities are encouraged to
automatically relink references to the URI requested to the new
reference returned by the server, where possible.
Note: It is possible for the server to send back this status
code in response to a request using the PUT and POST
methods. However, as this might change the conditions under
which the request was issued, the user agent should not
automatically redirect the request unless it can be
confirmed by the user.
==== end quote =====
I haven't tried this, though. I will be delighted to see if this works for you.
--
Chiaki Ishikawa ishikawa @
personal-media .
co .
jp
Personal Media Corp.
Shinagawa, Tokyo, Japan 141
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