SOA anti-patterns

A lot of emphasis has been placed on implementing Service Oriented
Software according to best practices and principles. But how about the
worst practices? In this article, Steve Jones from CapGemini goes over
some of the most egregious and thorny antipatterns based on his
experiences in the industry and discussions with other SOA thought
leaders.

The purpose of patterns is to define how systems should be built in
repeatable ways; the purpose of anti-patterns is to help you see when
that hasn’t been done.

Format

Each anti-pattern presented in this article will follow the following format:

  • Description – What it is?
  • Effect – What you see?
  • Cause – What behaviours led to that effect?
  • Resolution – What can be done to solve the problem?

Antipattern: The Shiny Nickel

Also know as the "Magpie"

Description

Used to incorporate the latest technology buzz within your SOA for
the sake of telling people about it. For example, introducing an ESB
for 2 services that have no translation or routing requirements.

Effect

SOA projects are characterised by their use of new technologies and
their product procurement cycle more than the actual solution being
delivered. Projects are talked about as being the "BizTalk", "WebSphere
Process Server", "SAP Netweaver", "Oracle Fusion" etc project rather
than the functionality the project aims to deliver. They are also
characterised by the sheer volume of technology and a massive turnover
in technologies being used. Technologies are rarely re-used from one
project to the next as IT delivery moves to the next shiny nickel. Each
project lays down another technology stratum that increases the cost
and complexity of support and creates an integration challenge for
future projects. This pattern sometimes evolves into the Technology
Altar when allowed to.

Sometimes Shiny Nickel creates project paralysis as the project is
continually delayed waiting for the "next" technology which will solve
everything.

Cause

The Shiny Nickel anti-pattern is often caused by lax procurement
rules and by a lack of common strategy in IT. Often driven by
"golf-course" product selection from business and IT, these products go
hunting for a solution. Often product procurement takes place
independently from projects, which leads to technology decisions on
projects being driven by a desire to minimise shelfware. Pet projects
and pet technologies go hand in hand with both feeding off the other,
projects are created because the technology can solve them, and the
technology is used to deliver a pet project.

Shiny Nickel is also caused by technologists reading websites and
going to vendor presentations and not investigating the detail of the
solution before the actual project.

Resolution

Fixing the shiny nickel is about knowing where you want to get to.
It means defining what you want your architecture and enterprise to
look like in a few years, and understanding the steps, standards and
therefore technologies that will take you there. It also means getting
a grip on IT procurement so decisions are ratified against the roadmap.

Antipattern: The Technology Altar

Description

IT sacrifices business focus on the technology altar; all focus is
on technical purity and a single IT "truth" for the enterprise.

Effect

This anti-pattern takes the form of a series of strategic IT
projects that are not well understood by business users and deliver
limited noticeable benefit. Business objectives are relegated to second
place and business projects are de-prioritised while IT creates its
strategic backbone, bus or SOA infrastructure. IT program is eventually
cancelled before completion and never delivers the benefits promised.
Single Canonical form, Enterprise Wide data models and infrastructure
and a "single" solution to all business problems are all proposed as
sensible solutions.

Cause

Sometimes linked to the Shiny Nickel anti-pattern this anti-pattern
occurs when IT has become clearly disjoint from its business and is
able to dictate both budget and focus for IT investment. The IT
organisation focuses on "strategic" IT projects which tend to be
focused on delivering a step-change in the organisation after several
years of investment and the creation of a solid base. By trying to
create an infrastructure in a single big-bang the IT organisation
becomes separated from the actual requirements and tends to sacrifice
sensible solutions is favour of technical perfection, it is this belief
in the primacy of IT that leads to things like single canonical form
and single EAI or ESB solutions being proposed without recognising that
the world may actually change.

Resolution

IT has demonstrated an inability to manage its own budget
effectively; the IT budget should be separated between Operations and
Investment, with Operations covering only "business as usual" costs. IT
Investment should be given to the business to spend on IT projects that
it wants to see; IT must then look across these areas and "sell" common
strategy elements across the business.

Antipattern: Percolating Process

Description

Organisations start with a detailed Process map and then attempt to
"fit" this into a Service Oriented Architecture; this refactoring leads
to process becoming the dominant feature and leads to a Process
Oriented Architecture (POA) rather than SOA.

Effect

An organisation’s "Services" come in two basic types, firstly
end-to-end processes that co-ordinate lots of individual steps, and
secondly a large set of fine grained services that represent individual
steps. Any hierarchy or structure is solely from the basis of process.
The fine grained services proliferate and become difficult to manage
while the large business process elements become difficult or
impossible to change. The systems slowly, or quickly, stagnate and lead
to solutions being built on top of the existing solution and the
general treating of the process oriented system as a legacy application.

Cause

The organisation has decided to map the processes and end to end and
in detail; the work has created a series of grand "end to end" process
models that are categorised by their large number of steps and the lack
of sub-processes that they use. Once this exercise has been done to a
great level of detail it is decided to make it SOA. The problem is that
the valid business services have not been identified and thus the
process maps have been created without a proper service structure. This
makes identifying valid services a tricky process particularly when
looking for cross-functional or horizontal services.

The challenge here is that the organisation has not started with
clarity on its services and hence has created a Process Oriented
Architecture. Retrofitting services into such an environment creates a
sub-optimal system that is liable to have all the issues of other
process based systems, such as COBOL.

Resolution

The first resolution is to independently of the process map create
your services architecture. This will provide the structure for
breaking down the processes and creating a clear hierarchy of use.
Next, this service architecture should be over-laid onto the process
map to understand where the cuts should be made. The current solutions
can then be refactored to create a more service oriented solution by
attacking the major inflexibilities in the system and then looking
towards incremental change of the current systems.

Antipattern: Point to Point Web Services

Description

Web Service point to point is STILL point to point; doing a bad practice in XML doesn’t make it better.

Effect

An organisation believes that they are creating a next generation
loosely coupled architecture just because they are using Web Services.
Web Service calls are invoked directly, using a URI which is hard-coded
into the WSDL. After a period of time the multiple web service calls
and dependencies lead to the Spaghetti infrastructure that EAI aimed to
solve. Having a highly disorganised and interdependent systems model
leads to increased cost of change and a high degree of fragility of the
enterprise. When one service is changed a number of other services
either fail or behave in unpredictable ways. There is a lack of clarity
as to how one service depends on another and what the impact of change
is across these services. Consumers then start demanding multiple
versions of services, and these add further to the spaghetti in the
enterprise.

Resolution

The first step is to indirect all of the calls and this can be done
in a number of ways; the least invasive is to "proxy" all web-service
requests via some form of mediation. So while the host application is
still calling webservice.mycompany.com, this is proxied so mediation
and routing can be applied if required. The next stage is to understand
the different dependencies and identify those which are valid and those
which should have been done in a more managed way. A clear governance
plan then needs to be created to identify and manage dependencies and
versions and to help manage the Web Service infrastructure.

Once this level of management has been created it is time to start
considering what the enterprise Service model should be, that requires
the creation of the business service architecture and then overtime
evolving the current infrastructure to better represent the business
that pays for it.

Antipattern: Splitting Hairs

Description

Splitting into two separate tiers of Service and Process, with separate rules and governance results in divergent solutions.

Effect

Applications and the enterprise are considered in distinct layers
with those layers having different governance models, different
technologies, and often at the enterprise level distinct project
teams.This layering results in competition between "Service" and
"Process" teams as to who should build new functionality; if the hairs
are split further it results in Data, Security and other elements all
being considered independently of each other and having different
approaches to interaction and management. The IT estate begins to
solidify around technology layers, rather than along business lines.
Work is created to "keep teams busy" or misallocated to different parts
of the architecture because one side or the other shouts the loudest.
It becomes simple to call Process from Process, or Data from Data etc,
but becomes difficult to call Process from Service and Data from
Service as teams create their own special ways of working. The rate of
change in the IT estate slows first in one layer and then in another.
There is a lack of standardisation across the enterprise and the layers
start being considered as a number of discreet, and now legacy, systems.

Resolution

The first step is to break the teams away from being centred around
technologies and layers and becoming centred around the business
services that you are trying to deliver. While the technologies for
services that contain higher level orchestrations and those which
deliver core logic will be different this should only be apparent
inside the services, externally there must be a common mechanism and
standard for how services are discovered and consumed.

This anti-pattern tends to occur when organisations become fixated
on the technologies they are using to deliver rather than on the
capabilities they are attempting to deliver with it. Keeping people
focused on the function over the technology helps prevent this layering
solidifying. It is important to clearly identify the right technology
in which to implement a given set of capabilities, and then to make
that set of capabilities exposed and accessed in a common way.

Antipattern: IT2B

Also known as "The people’s republic of IT".

Description

Creating "business" services based on the belief that IT understands
the business results in services that meet neither IT nor business
goals.

Effects

IT decides to do SOA and then presents the results to the business.
They create a services structure without consulting the business based
on a best-guess using previous project learnings. IT then creates
specific orchestrations through these services which represent their
view on the "optimal" business processes. This is often done using a
packaged solution and IT fails to take into account the cost and impact
of change, which dooms the exercise. The service architecture created
is then used as the basis of future IT project planning decisions, but
as this does not match the business view it fails to deliver the
expected benefits and becomes extremely strained as IT struggles to
manage change within an invalid architecture. The IT estate becomes
more complex and unmanageable with a large amount of fragility as the
dependencies between services increase.

Resolution

Similar to the technology altar, the first stage is to clearly align
the business with IT. It’s possible that the reasons IT undertook this
approach was because they did not receive clear long term direction
from the business. The first stage must clearly identify what the
services should be and then work on identifying how current services
can be broken down and re-assembled along the correct lines. There
should be clear business aligned governance within IT to make sure that
future decisions are based around business drivers rather than ad-hoc
best efforts decisions.

Antipattern: DIY Transport

Description

An organisation decides to build its own proprietary XML-RPC stack or other technology in order to have more "control".

Effect

To allow your service implementation team to start to develop
their own concept of a protocol, transport or any service delivery
mechanism. For instance, SOA over < ahref="http://www.ietf.org/rfc/rfc1149.txt?number=1149">RFC
1149 for interconnential service providers is probably not needed. This
is often done in the mistaken belief that a companies’ requirements are
"unique", or because the technical team is planning for future possible
requirements. The solution becomes more and more complex as the
in-house team has to turn into a product development group, integration
with other solutions becomes harder due to the lack of standards
support and upgrades to new COTS and non-COTS solutions are delayed
while the in house product is created.

Resolution

Rip out the proprietary solution and replace with a standard based
Open Source or COTS product. The earlier this is done, the more money
it will save in the long run.

Antipattern: Nobody Home

(credit goes to Dan Marchant)

Description

Used to allow a service implementation team to define services
without a glimmer of hope for a client to actually use the service.

Effect

Services are created based on perceived rather than actual needs;
these result in a proliferation of services without any consumers.
However these services still require management and deployment.
Services are exposed by developers from IDEs because it is "possible"
rather than because it needs to be done.

Resolution

Create a company "register" of services and have a regular policy of
removing services that have no consumers. Also educate people on your
enterprise SOA so they know the sorts of services that are required.

Antipattern: Too many Cooks in the SOA

Also known as "A maze of twisty services, all alike".

Description

Multiple services with the same functional behavior are added to the
registry without each group checking for service functionality
beforehand. It is the proliferation of services that are identical to
each other but are supported by different teams or within the same team
in the enterprise.

Effects

Projects are more interested in building services than in re-using
them; the numbers of services proliferates while the amount of
functionality increases slowly. A culture of build and expose becomes
endemic and the enterprise becomes a mess of services all attempting to
do the same thing. Projects do not benefit from re-use, so costs are
not reduced in development and the proliferation of services makes
management of services more difficult. Change is in particular much
harder as it must be applied in several different places.

Resolution

The reason that projects create lots of services is that they are
allowed to. Governance and tracking needs to be put in place to enforce
re-use. A simple recommendation is to fund service development
differently from project specific functionality, thus re-using service
functionality from elsewhere frees up additional budget for the project
functionality, and the creation of genuinely re-usable services results
in additional investment in the project to help create those services.

This needs to be combined with a simple search facility that enables people to quickly find the services that already exist.

Antipattern: UBER service

Description

The anti-pattern of creating a very limited set of services, or even
just one, to try and provide all functionality within the enterprise
SOA, related to Singleton SOA Anti-Pattern. This causes the
functionality and operations being added to a service, to be mushed
into a group of functionality that may or may not be related, creating
tight coupling between them.

Effect

The desire to not create more services becomes a consuming passion
for the organisation and services gain larger and larger interfaces
representing more and more diverse functionality. Updating services
begins to take longer as the conflicting requirements of these
different pieces of functionality make change harder to implement.
Behind these large service boundaries a separate layer of services
often develop which are then aggregated behind the "uber" service
interface. These lower level services become directly used via covert
means within the enterprise, meaning that visions of centralised
management become lost.

Often this approach occurs in connection with a DIY approach to
security and management, the reduced number of services making the
custom development simpler. Unfortunately this re-inventing of the
wheel leads to a lack of standardisation making future package and
service purchase decisions more complicated and it is very brittle to
future change.

Resolution

Firstly determine what the true enterprise services, then go out and
buy products that make this easier to manage. Then start breaking down,
or even just removing, the uber-services. Implement the centralised
governance using a proper governance solution and manage interactions
between the services using a proper mediation engine.

Antipattern: A Million Services all in a row

Description

Standard anti-pattern where organisations go "Service Crazy" with a
massive number of services created to result in a quantity rather than
a quality of service.

Effect

Organisations approach SOA as a race to expose as many services as
possible, to enable as much re-use as possible in a period of time as
short as possible. This tends to be driven by technologists using IDE
tools to "right-click" and expose elements as a web-service.

The organisation developers taking pride in the "number" rather than
the quality of services is a prime symptom. This is all done with a
total lack of a "big picture" as to what the organisational services
should be. These efforts tend to be driven out of IT organisations that
are often disconnected with the business and are focused purely on Web
Services. These approaches are driven by a desire to directly expose
technical code. No mediation or grouping occurs and even non-functional
elements are exposed in the desire to create as many services as
possible.

This results in a large number of normally fine grained services
with a very close binding of Web Services to implementation. There is a
total lack of structure with no business alignment. Added to this there
becomes a large amount of point to point calls being made that help to
create the start of the "rats nest" problem. The basic root cause of
this is that the technologists mistake SOA for Web Services and as a
result try to create as many as possible to look cool.

Resolution

The first step is the cleansing and categorisation of services for
deletion or refactoring, mostly deletion. This should include the
complete removal of created artifacts, if they haven’t been used yet.
The IT organisation then needs to start to understand how the business
operates and focus on creating services for the business rather than
engaging in a web services arms race. This means the creation of the
over-arching "big picture" and migration plan for the existing services
to the "To-be", generally involves simply asking the business what they
want!

Antipattern: Architectural Stovepipe

Description

An enterprise architecture that levels too many expectations on
present and future applications. One example occurred during the MOM
era, where in order to conform to requirements from the enterprise
architecture contained applications suffered unnecessary complexity.

Effects

An Enterprise Architecture group seeks to establish a "grand plan"
with a big and bold vision for the future. This architecture has been
created separately from implementation teams and seeks to address large
strategic challenges of the business. Unfortunately it becomes a tenant
of faith that all of the architecture should be implemented as it is,
which leads to excessive complexities on even the simplest project. The
Enterprise Architecture group holds a compliance position over projects
and isn’t burdened by technical or project realities; this begins to
create a clear separation between the enterprise vision and the
projects, as a culture of avoidance is created. The Enterprise
Architecture often fails to be modified as business objectives change,
or is modified in a yet more complicated and "visionary" way.

The Enterprise Architects become disconnected from the business and
are seen like White Robed philosophers coming down from Mount Olympus
preaching wisdom and visions of the future; this is beginning to be
seen more an entertainment than an enlightenment.

Finally the Enterprise Architecture is abandoned and the resultant
projects and infrastructure become yet another stratum of the
enterprise infrastructure.

Resolution

Firstly the Enterprise Architecture must be "kept real"; this means
both in terms of its vision for the business and the practical
realities of delivery. Having a visionary architecture that is created
first and only then mapped to technology doesn’t result in the best
architectural vision; it must be tightly bound by what can be done, as
well as what should be done in future.

The Enterprise Architecture must have a clear practicality and
implementation roadmap; it must say what the steps towards the final
vision are and must present the costs that justify each of these steps.
The vision should be that of the business rather than of an
architectural "purity" that exists only for its own aims.

Generally the architecture team should be led by someone who understands implementation problems and challenges.

Antipattern: Defensive SOA

(credit to Miko Matsumura)

Also known as "Optimistic SOA".

Description

The default answer produced by your Information Technology group
whenever asked is "we already ARE doing SOA". Certainly there is
nothing wrong with this response if it were true. But beware
"definitions" of SOA that do not meet the organizational requirements.
This is a SOA Governance problem, in the sense that SOA for your
organization needs to be defined to the extent that the benefits are
clearly articulated, measured and audited. Traditional software
development is filled with extremely bright people. The significant
challenges faced by organizations grappling with the large list of
external changes and the difficult processes all seem to invite
developer focused solutions. But in many cases you can’t solve the
problem in the mindset you used to create the problem.

Effects

A number of change management mechanisms have emerged as a way to
deal with changes. All of the technologies listed here are virtuous and
powerful. Seeing the presence of these techniques in and of themselves
does NOT denote an anti-pattern.

The concern is that the use of band-aid solutions to solve
short-term pain forestalls the advancement of solutions to the chronic
problem of fundamentally inflexible IT.

The use of the following solutions UNDERNEATH the service interface
can be cause for alarm-because agility in SOA is defined in policies
and metadata constructs (like BPEL) which sits ABOVE the service
interfaces. Once again, there is absolutely nothing inherently wrong
with any of the following technologies, save for when their use
precludes and obstructs the advance of network centric SOA.

1) Aspect Oriented Programming

A powerful system which enables transformation of software systems
through "join points", "code weaving", "point cuts" and "cross cuts".
AOP is primarily a design time programming model, thus subject to all
of the complex lifecycle processes involved in testing and deploying
new software projects in the Enterprise. Using AOP to do things which
could better be done by a policy enforcement point is a warning sign.

2) JRS175 Metadata within Java Code

This capability allows metadata tagging to be subsumed within Java
code. This has many uses but can also be abused as a way of injecting
declarative policy sets within Java code. This has the disadvantage of
being configurable only by Java programmers.

3) Spring and other frameworks

Another powerful system for managing change involves the use of
powerful programming frameworks. Spring, for example, has a variety of
features, but most noteworthy are the Inversion of Control features
which enable dependency injection. These features can be used to manage
highly changeable software environments.

4) Test first development

By building a robust use case based test harness before implementing
code, a virtual "contract" is built. The semantics of that contract are
all of the test conditions for the service. This seems to be a strong
approach to change management, as it provides a solid way of assessing
if changes would impact use cases. Unfortunately, the test cases are
hard to verify in a way that captures all possible changes and
externalities.

5) Source Code Reuse "Repositories"

Leveraging source code repositories for reuse is not SOA. Reusing a
deployed service is transacting against a live Enterprise asset.
Reusing source code does not save the organization from the complete
application development, testing, provisioning, deployment, approval
and other application development lifecycle requirements.

None of these mechanisms intrinsically enables the alignment of
business and IT constituencies because the complexity and control of
policy and of the model gets stuck squarely in the development
organization.

As implementation techniques for services, these are well and good,
but if your entire architecture can sit inside of a single virtual
machine, you may have a problem.

Cause

In 90% of cases, when business people go to conferences and come
back with a buzzword, they are wrong and need to be appeased.
Therefore, when developers see business people coming back from SOA
conferences, they react in this defensive way. Unfortunately, SOA is
within the 10% of the time where the business user actually has it
right. Flexible IT, Business Agility, Business IT alignment are all
sorely lacking in tightly coupled land, and SOA can actually help.

Resolution

This requires business people to actually try to understand what IT
are doing. It also requires IT people to understand what business
people are trying to do. Mechanisms like service interfaces, BPEL
diagrams and other abstractions can help smooth the conversation.

Warren Buffet has a saying "If you can’t understand it, don’t invest
in it." This applies strongly to SOA. If a business person is sold a
very complex UML diagram or a mind boggling looking development
process, it’s incumbent upon them to ask for a clearer articulation-and
it’s incumbent on the IT people to provide that. If the SOA
implementation plans coming out of IT are filled with extremely
Byzantine gobbledygook, you need to send IT back to the drawing board.

What aligns business users and techies in SOA is that it should be
operating at a level of abstraction that is easily understandable to
both sides. If that’s not the case, it’s time to get worried.

Reference:

http://service-architecture.blogspot.com

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