Hi Steve,
when
you refer to "lots of services", how many services are you thinking of?
Likewise, what do you consider to be a low number of services? Can you give
some examples or service ratios that you think would be "too much" and "just
right".
Regards
Theo
From: Jones, Steve G
[mailto:]
Sent: Monday, October 31, 2005
07:30
To: Beack, Theo; Davies Marc; Ken Laskey; Miko
Matsumura
Cc:
Subject:
RE: [soa-blueprints] Anti-Blueprints
Given the maturity of
most SOA elements (Ovum had a great report recently on the “missing M and silent
A”) the number of services is, for me, a bell weather on how a company is
approaching SOA. Lots of services has, so far, always meant a technically
driven approach with “right click” integration styles, organisations with
services in the low numbers have normally planned their first set of
services.
Once the world is more
mature in SOA then it will be less appropriate to use size as a guide, but right
now its extremely unlikely that an organisation has an established architecture
that has resulted in several hundred services being created from
it.
Steve
From: Beack, Theo
[mailto:]
Sent: 28 October 2005 00:46
To: Davies Marc; Jones, Steve G; Ken
Laskey; Miko Matsumura
Cc:
Subject: RE: [soa-blueprints]
Anti-Blueprints
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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825118
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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
T +44 870 906 7026| 700 7026| www.capgemini.com
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txt: +44 (0) 7891157026
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