Subject: Message Bus vs libraries

From: Anders Kristensen <[email-masked]>
Date: Wed, 14 Oct 1998 17:29:06 +0100

>From <draft-ietf-mmusic-mbus-transport-00.txt>:

   In the Mbone community a model has arisen whereby a set of loosely
   coupled tools are used to participate in a conference.  A typical
   scenario is that audio, video and shared workspace functionality is
   provided by three separate tools (although some combined tools
   exist).

This may traditionally have been true for the Mbone but it isn't the
case for any popular, mainstream platform that I know of. Arguably the
two most important platforms today are Windows and Java, both of which
adopt a completely different approach to enabling independently
developed components to work together.

Basically the approach taken by these architectures is to hide the
implementation of a particular "media engine" behind an SPI (Service
Provider Interface), and have the application program to some generic
(provider-independent) API. The provider is typically packaged as a
library, eg a dll or a jar file in the case of Java. Another example of
this sort of approach is the DOM defined by the W3C. I think JMF, the
Java Media Framework, addresses much the same set of problems as the
MBus proposal, and it seems to me to be the way you'd want to compose
applications on that particular platform at least.

The idea of defining a platform on top of the OS which is much more than
basic OS services never seemed to catch on for Unix so maybe something
like the MBus is more natural for Unix than it is for PCs, say. But I
don't think it's very likely that the message bus school of thought will
ever become popular on these other platforms. Maybe it would be an idea
for the MMUSIC WG to get involved in the standardization of MM APIs,
although this would probably be stepping on teh toes of the likes of
Micro- and JavaSoft.

Just a thought.

Anders
-- 
Anders Kristensen <[email-masked]>,
http://www-uk.hpl.hp.com/people/ak/
Hewlett-Packard Labs, Bristol, UK

---

From: "Henry Sinnreich" <[email-masked]>
Date: Wed, 14 Oct 1998 14:24:55 -0500

Anders wrote:

>Maybe it would be an idea

1. Agree: "Standardizing" on an OS controlled by a company is not a good
option on the Internet.
2. The network requires protocols to make it work: Addressing, security,
delay, packet loss, etc.
     It's not a backplane or LAN.

Henry

> -----Original Message-----
> From: [email-masked] [mailto:[email-masked]]On Behalf Of
> Anders Kristensen
> Sent: Wednesday, October 14, 1998 11:29 AM
> To: [email-masked]
> Subject: Message Bus vs libraries
>
>