Re: [service-orientated-architecture] SOA and ESBs

[Anne Thomas Manes]

Stu,

You are making an argument for medaition systems. I'm just pointing out that ESBs aren't the only type of mediation system out there. I can do all these functions with an XML gateway or a SOA management system. Plus I get more robust management and security than with an ESB.

Anne

On 6/27/06, Stuart Charlton <[EMAIL PROTECTED]> wrote:

The way I view it:

- an ESB is an optional decentralized proxy service
- it can monitor or enhance a service's capabilities
without requiring modification to a downstream service
- ESBs might also help to manage dependencies and
interface evolution
- the major benefit is that it should be more
productive than building these things in a framework
of your own
- lock-in is a fact of life, even if you build
something yourself -- those people could leave, and
you've lost your braintrust

The reason it's useful is because service contracts
are constantly evolving. New breeds of consumers
evolve, with different requirements. New classes of
QoS are required... etc. You can evolve the source,
or use an intermediary as lubricant. Either approach
has its appropriate context.

For example, if one creates a bunch of SOAP/RPC
time-series data services, wouldn't it be useful to be
able to overlay an RSS or Atom feed on top of them, so
a new class of consumers could access those services?
Sure, you could build such an overlay.... or you
could modify the source service and add another
endpoint / content type... or you could use an ESB.
Which would be more productive? It depends on your
context...

Anyway, to me an ESB is similar to the concept I've
heard of a "SOAP Router" 3 or 4 years ago, though
ideally should allow a variety of protocols. Not
mandatory, but useful.

Of course, the marketplace is pretty confusing about
what is/is-not an ESB, and how much priorietaryness
is/should-not be there, etc., so the risks are high
enough to be cautious.

Cheers
Stu

--- Dennis Sosnoski <[EMAIL PROTECTED]> wrote:

> Hi all,
>
> I'd like to find out how list members view the use
> of ESBs in SOA. Based
> on what I've read and discussions I've had off list,
> I suspect a fair
> number of people view an ESB as an essential
> component of a SOA.
>
> In my own talks on the topic I tell people that ESBs
> are especially good
> for bridging legacy applications to a SOA. Beyond
> this, they can
> certainly add a lot of value in the monitoring and
> control area.
> However, I think there's been way too much marketing
> hype from the
> vendors that conflates ESBs with SOA. Especially now
> that WS-Addressing,
> WS-ReliableMessaging, and WS-AtomicTransactions are
> becoming standard
> components of the SOAP stacks (and WS-Eventing is
> getting closer), the
> value added to Web services by an ESB seems to me to
> be minimal for all
> but the largest enterprises.
>
> The main drawback I see to using an ESB is that
> you're building your
> enterprise around proprietary software. Even the
> open source ESBs all
> have their own unique ways of configuring and
> managing services. The net
> effect is that you're locked into a particular
> service bus and will find
> it increasingly difficult to break free over time.
>
> How do other people feel about this?
>
> - Dennis
>
> --
> Dennis M. Sosnoski
> SOA, Web Services, and XML
> Training and Consulting
> http://www.sosnoski.com - http://www.sosnoski.co.nz
> Seattle, WA +1-425-296-6194 - Wellington, NZ
> +64-4-298-6117
>
>
>
>

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