Re: [Fwd: Re: Mainframe not a good architecture for interactive wasRe: What is the future of COBOL? Answer: Irrelevant???]]

From: Michael Wojcik (mwojcik_at_newsguy.com)
Date: 01/28/04 

Date: 28 Jan 2004 21:23:17 GMT

In article <RwwRb.120657$6y6.2389843@bgtnsc05-news.ops.worldnet.att.net>, "Hugh Candlin" <no@spam.com> writes:
>
> John S. Giltner, Jr. <giltjr@earthlink.net> wrote in message news:zTlRb.146$zG1.71@newsread3.news.atl.earthlink.net...
> >
> > Yes, HTTP as a defined protocol can create as many connection as allowed
> > However, most modern web browser limit the number of connections created
> > to render a single web page to 5.

> Microsoft Knowledge Base Article - 183110
> INFO: WinInet Limits Connections Per Server
> http://support.microsoft.com/default.aspx?scid=kb;en-us;183110

We're off-topic (as usual), but here are a couple of brief comments
about that article:

1. It's out of date. RFC 2068 is no longer the HTTP/1.1 specification;
RFC 2616 superceded it. However, the relevant material in this case
appears to be unchanged.

2. It's misleading if read over-broadly. It's about WinInet, not HTTP
clients in general. RFC 2616 says:

   Clients that use persistent connections SHOULD limit the number of
   simultaneous connections that they maintain to a given server. A
   single-user client SHOULD NOT maintain more than 2 connections with
   any server or proxy. (8.1.4)

Points to note:

- This is a SHOULD requirement. It's mandatory for full compliance,
but not for conditional compliance.

- It applies only to clients that use persistent connections. That's
probably not the case in the example John gave, since persistent
connections are generally combined with pipelining, and a pipelining
client doesn't want to open multiple connections to the same server.

- It applies only to single-user clients.

- There are other recommendations for proxies. If your HTTP server is
serving a fully-compliant HTTP/1.1 proxy, it might well have more than
2, or 5, connections.

HTTP/1.1 is a fairly complex protocol - it's not LU6.2, but it's not
SMTP either. It's often not the best choice for an example because
it's hard to remember everything in the spec, existing practice is
frequently non-compliant, and many people are confused about what the
spec actually requires. 

-- 
Michael Wojcik                  michael.wojcik@microfocus.com
HTML is as readable as C.  You can take this either way.  -- Charlie Gibbs

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