Hi
Marc,
I
wrote that email quite early in the morning, so I was not as precise in my
wording as I would have liked. Anyway, I would like to further qualify my
statement with regards to the number of services.
I
don't consider the number of services to be an
accurate indication of either a good or bad approach, *if taken at face
value*.
You
need the appropriate context around the numbers to make sense of them. Let me
use an example to illustrate. When city planners are working on a new city master plan, how
do they determine whether a city or
certain borough within that city might be
overpopulated? How do they determine
whether there is sufficient infrastructure and resources available to support
the existing population? How do they determine whether the existing
infrastructure can support future growth? Do they only look at
the number of people in the city and then make a judgement call whether it is
overpopulated or not and whether it can support
future growth?
I
would venture to say that their calculations and models would be far more
complex and incorporate a large number of different factors, in order to
accurately determine the appropriate population size.
As an example, if a certain city had a
population of 3 million, would that be an indication that the city if
overpopulated? It is difficult to say. If one knew that the city is Hamilton, MT one would be
safe to assume that Hamilton would be wildly overpopulated. If the
city on the other hand, was the borough of Manhattan one would be quite safe in
assuming that the city is not overpopulated, due to the fact that it has
adequate housing, transport infrastructure, utilities, water supplies, etc. . .
.
I
think some of same principles apply to SOA implementations. Organizations vary
in size; their IT environments also vary in size and complexity. A small company
of around $100M - $200M with an IT department of around 100 people and 10-20
different systems would most likely not require hundreds of services. If you
told me that they had 400-500 services, then I would most likely question the
appropriateness of this number of services.
If
the organization in question is a large multi-national corporation with revenues
of several billion $, one can be certain that it will have a much larger IT
infrastructure to support the business. The application ecosystem will be large,
with a lot of complexity and integration requirements. If the number of services
deployed is also within the 400-500 range, it would still be difficult for us to
tell whether there are too many services and whether they are making good reuse
of all these services. I think it would be prudent, in both cases, to
investigate and do a proper analysis to determine whether good SOA design
principles have been followed.
So
in summary; I agree that the number of services should be one of the factors
that one need to incorporate into the analysis, while factoring in the context
of what you know about the overall application infrastructure, complexity,
integration requirements, etc.
Regards
Theo
From: Davies Marc
[mailto:]
Sent: Thursday, October 27, 2005
06:52
To: Beack, Theo; Jones, Steve G; Ken Laskey; Miko
Matsumura
Cc:
Subject:
RE: [soa-blueprints] Anti-Blueprints
Sorry Theo but, I think
Steve is on to something with anti-patterns and I *do* consider the number of services to give
an indication of approach. In
particular your comment:
- 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
…Implicitly indicates
to me that (in that example) this is not an SOA environment. An SOA journey
must have strong centralised (architectural) control ensuring developers do not
just ‘do it’ how they think is the best way forward for “their” application
(which in reality of course, isn’t their application – it’s the business’
application, a fault many of us have suffered from at some point in our careers,
I’m sure :o)
SOA is not WS (IMHO),
SOA does mean strong Governance and adherence to standards, and this may
frequently upset Developers!
M.
Marc
Davies
Fujitsu
Business Unit
Chief Technology Officer
Architecture
& Design Group
Core
Services
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From: Beack, Theo
[mailto:]
Sent: 27 October 2005 05:15
To: Jones, Steve G; Ken Laskey; Miko
Matsumura
Cc:
Subject: RE: [soa-blueprints]
Anti-Blueprints
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
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