I don't consider the number of services to be an accurate indication of either a
good or bad approach. I think that one has to be more precise in measuring the
relative maturity of the services that exist. Factors that can help one
determine the "maturity index" of the SOA
implementation might include:
- level of reuse,
- scope of the services,
- service
granularity,
- adherence to architectural
blueprints,
- compliance
with standards, etc.
This is not a comprehensive list and one can
take different views on how to measure the maturity of the services
implementation, but the point I'm trying to illustrate is that one has to look at this from different angles in order
to determine whether the approach which has been followed is a good or "bad"
one.
The
statement “We’ve got hundreds of web services and it hasn’t helped us
at all” is only a symptom of a potentially larger (or
real) problem. The lack of reuse can be caused by factors such
as:
-
developers might find it difficult to find the
appropriate services,
- several conflicting services might exist that
provides similar functionality,
-
instability or lack of performance of services & infrastructure might cause
developers to abandon the use of
services,
- it
might even be a cultural barrier; developers might think using
services is a waste of time and prefer to integrate their apps in another
way
In my experience many
organizations create services without doing any planning. Many tools allow them
to do this in a very easy manner and developers could easily created a large
collection of services, without any planning. Following a good services design approach might be an
important step to create truly reusable services. Determining the purpose of the
service, who the primary consumers will be, usage patterns, interfaces required
for the various consumers, service security, documentation, proper metadata,
etc. all of these aspects of a service should be considered and might play an
important part in making it a usefull and widely used service.
Regards
Theo
From: Jones, Steve G
[mailto:]
Sent: Tuesday, October 25, 2005
17:12
To: Ken Laskey; Miko Matsumura
Cc:
Subject: RE: [soa-blueprints]
Anti-Blueprints
In other words has
someone just “right-clicked” on a JavaBean (or C# object) and selected “Create
Web Service” from the menu, or was there actually planning and intent?
I’ve actually seen organisations where just this sort of exercise has been
undertaken creating the thousands of web services problem.
Number is part of the
issue, its indicative of a bad approach when organisations create thousands of
DISTINCT (as opposed to instances) of web services. But the Service should
have a qualitative impact on the “real-world” or provide a useful function (e.g.
mathematical calculation) this stuff is in the SOA-RM as being the basis of
service.
In terms of numbers I’d
say that volume is an important
indicator of bad practice, not a definitive guide but its getting a more and
more common statement “We’ve got hundreds of web services and it hasn’t helped
us at all”. Clearly its possible to have lots of top quality services, in
the same way as in theory its possible for people to write decent multi-threaded
code but in practice both are normally indicators of problems.
Steve
From: Ken Laskey
[mailto:]
Sent: 25 October 2005 21:47
To: Miko Matsumura
Cc:
Subject: Re: [soa-blueprints]
Anti-Blueprints
The question is less one of number than independence.
Does the original interface (method call) provide a capability that is useful
beyond the object with which it is connected and can it be used without being
part of a sequence with other methods from the same object?
Ken
On Oct 25, 2005, at 4:10 PM, Miko Matsumura wrote:
Good feedback
Duane.
This is a good topic,
thanks for introducing it, Steve.
The number of
services *is* a quantitative measure, but perhaps not a very helpful one?
=)
I'm pretty sure
there's an antipattern here, and I think perhaps there could be some kind of
way to assess this. I think another variable in this mix is the extent to
which the registry repository in question can help with respect to discovery
and classification as well as governance. The thing that worries me is when I
see people assuming that fine grained (object level) services will be reused,
when the reality is that OO didnt generate that much reuse from even the guy
in the next cubicle, let alone across the company or across the
planet.
I think this is less
of a gross number of services antipattern so much as a coarse-grained vs
fine-grained antipattern...
Best,
Miko
From: Duane
Nickull [mailto:]
Sent:
Tuesday, October 25, 2005 12:57 PM
To:
Subject: RE:
[soa-blueprints] Anti-Blueprints
I disagree with this
anti-pattern.
I am not sure that
the number of services is really a quantitative measure of SOA. A grid
computing cluster administrator may be able to rationalize such behavior,
although it may seem absurd in other areas such as Amazon deploying a service
for each book it carries vs. deploying one service that allows the consumer to
parameterize the book title.
Perhaps a better
measure would be the development of some test criteria to ascertain whether a
contemplated service is a good candidate for repurposing beyond a small number
of consumers. This should be based on alignment with LOB and presumably
different implementers will have different criteria for quantifying
such.
Duane
From: Miko Matsumura
[mailto:]
Sent: Tuesday, October 25, 2005 12:41
PM
To: ;
;
Subject: RE: [soa-blueprints]
Anti-Blueprints
I just added a
"microservice" antipattern where programmers put 10000000 WSDLs into a
registry just because their IDE lets them do so.
Miko
From:
[mailto:]
Sent: Tuesday, October 25, 2005 11:54
AM
To: ;
Subject: RE: [soa-blueprints]
Anti-Blueprints
Steve,
Good idea. I put up
the first drafts of them at: http://blueprints.jot.com/WikiHome/SOA+Anti-Patterns/SOA%20Anti-Patterns
Let me know if I
correctly eloborated and named them for you.
Thanks,
Dan
-----Original
Message-----
From: Jones, Steve G
[mailto:]
Sent: Tuesday, October 25, 2005
11:21 AM
To:
Subject: [soa-blueprints]
Anti-Blueprints
The SOA Blueprints will lay down
a “best practice” set of guidelines and templates for delivering SOA.
This will definitely be a positive thing and help expand and firm up
people’s understanding of SOA. One thing that the group states that it
will do is define standards and guidelines, does this mean that allied to
our blueprints we must also consider the “anti-blueprints” (analogous to
anti-patterns) that must be avoided. So for instance focusing on
process over service (bad), only thinking of web services (bad) etc
etc. Defining the blueprints give guidance towards success criteria,
but should we also give guidance on failure criteria for acceptance of a
system as being “SOA”.
Not sure whether this should be
in the TC as its laying down best practice, and not to increase the already
large workload… but it needs to be somewhere.
My top 5 are
1)
If you’ve started with an
enterprise “best practice” process map you are NEVER going to be SOA and 90%
probability your system will be inflexible or fail.
2)
Web Service point to point is
STILL point to point, doing a bad practice in XML doesn’t make it
better
3)
Splitting into two separate
tiers of Service and Process with separate rules and governance results in
divergent solutions
4)
Creating “business” services
based on the belief that IT understands the business results in services
that meet neither IT nor business goals
5)
Building your own proprietary
XML-RPC stack to give yourself “control“
The last could still be SOA from
one perspective, but I’ve yet to see it done well when the driver was a
belief that its better done in house than using standards. When we get
the official Wiki it could be something to document via that
route.
Steve
___________________________________________________________
Steve Jones | Capgemini
CTO, Application Development Transformation
T +44 870 906 7026| 700 7026| www.capgemini.com
m:
txt: +44 (0) 7891157026
Join the Collaborative
Experience
___________________________________________________________
This message contains information that may be
privileged or confidential and is the property of the Capgemini Group. It is
intended only for the person to whom it is addressed. If you are not the
intended recipient, you are not authorized to read, print, retain, copy,
disseminate, distribute, or use this message or any part thereof. If you
receive this message in error, please notify the sender immediately and
delete all copies of this message.
------------------------------------------------------------------------------------------
Ken Laskey
MITRE Corporation, M/S H305 phone: 703-983-7934
7515 Colshire Drive fax: 703-983-1379
McLean VA 22102-7508
This message contains information
that may be privileged or confidential and is the property of the
Capgemini Group. It is intended only for the person to whom it is
addressed. If you are not the intended recipient, you are not authorized
to read, print, retain, copy, disseminate, distribute, or use this message
or any part thereof. If you receive this message in error, please notify
the sender immediately and delete all copies of this
message.
