SOA Anti Patterns

7/27/2019 SOA Anti Patterns

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Copyright IBM Corporation 2006

SOA Anti-Patterns

Paul Ashley and Tony CarratoEnterprise Integration SolutionsIBM Software Group

[email protected],[email protected]


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Presentation Agenda

Objectives

What are patterns

And, thus, what are anti-patterns

Why patterns & anti-patterns are important

SOA Anti-patterns for SOA

The project Im working on about anti-patterns

And how you can contribute Where to learn more


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Objectives

Identify common obstacles facing SOA from adoption torealization

Describe the obstacles and provide suggestions for solutions

Solicit input to add to the discovered AntiPatterns

Publish the findings for the benefit of the practitionercommunity


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A Pattern is a "generalized, named problem to solutionmapping

A Pattern captures a successful solution to a repeatingproblem in a particular context

In general, a Pattern is documented using the following:

Name: A name used for identification

Problem: A repeating problem that occurs in a

domain

Solution: Best practice solution to that problem

Consequences: Advantages and disadvantages of therecommended solution

Examples: A few examples where therecommended solution has already been applied

Christopher Alexanders research on buildings and town

design is often considered the pioneering work on Pattern-based thinking.


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Provide a mechanism to capture knowledge and experience

Provide a common vocabulary among architects anddesigners

Facilitate reuse of approaches that have been successfulelsewhere and, thus, contribute towards the following

aspects of a project :

Reducing risk

Increasing quality

Improving delivery time

Why Patterns are important?


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Several Levels of Patterns

Business patterns that identify the interaction between users,businesses, and data.

Integration patterns that tie multiple Business patterns togetherwhen a solution cannot be provided based on a single Businesspattern.

Composite patterns that represent commonly occurringcombinations of Business patterns and Integration patterns.

Runtime patterns that define the logical middleware structuresupporting an Application pattern. Runtime patterns depict themajor middleware nodes, their roles, and the interfaces betweenthese nodes.

* Source: IBM Redbook: Patterns: Applying Pattern Approaches V2, May 2004


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Several Levels of Patterns

Product mappings that identify proven and tested softwareimplementations for each Runtime pattern.

Best-practice guidelines for design, development, deployment, andmanagement of e-business applications

Will have:

A name

The problem solved (goal) & forces which apply

A description of how the pattern works

Usually with a diagram (architects love diagrams)

An implementation section, e.g. a UML model

Examples of use

Source: IBM Redbook: Patterns: Applying Pattern Approaches V2, May 2004 http://www.redbooks.ibm.com


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AntiPatterns what went wrong

A frequently used, but largely ineffective solution to aproblem

The term was originally used to refer to a design pattern gonewrong

Document commonly recurring solutions that havecounterproductive effect

Typically capture refactored solution description, showinghow to change the AntiPattern into a healthier solution

Described by template or language and include identifying:

symptoms,

consequences root causes, and

potential solutions


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A Tool to Prevent Problems

Helps to identify a problem before it becomesa problem

Provides knowledge to prevent or recoverfrom problems

Documents what does not work

Provides a common vocabulary

Provides detailed remedyProvides awareness of situation and alternative

solutions

Todays hot solution can be tomorrowsAntiPattern

Why AntiPatterns are Important?


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An anti-pattern is a known-not-to-worksolution to a problem

Like patterns, anti-patterns come at various levels:

ModellingProject Management & Methodology

Architecture/Design

Assembly/Development

Performance ManagementTesting/QA

Deployment

System Management

Problem determination

Why AntiPatterns are Important?


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Greater flexibility is required from the business

models and the supporting IT Architecture

Flexible Business

TransformationBusiness Process Outsourcing

Mergers, Acquisitions & Divestitures

Flexible IT

Cost ContainmentGreater ROI for IT dollars

Better Use if IT Assets

Improved Quality of Deployed Systems

Requires

On Demand Operating Environment

Development Infrastructure Management

Service Oriented Architecture (SOA)

SoftwareDevelopment Integration

InfrastructureManagement

Composable

Services(SOA)

ComposableProcesses

(IBMComponent

Business Modeling)

Servic

e-

Oriented

Modeling


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SOA in context

a set of services that a business wants to expose to their customers

and partners, or other portions of the organization

an architectural style which requires a service provider, requestor anda service description

a set of architectural principles, patterns and criteria which addresscharacteristics such as modularity, encapsulation, loose coupling,separation of concerns, reuse, composability and singleimplementation

a programming model complete with standards, tools andtechnologies such as Web Services

Business

Architecture

Implementation

What is Service-Oriented Architecture?


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A SOA is composed of processes, services and

components. At the heart of the SOA is the Service Modelthat defines services and components that realize them.

serv

icemodeling

serv

icemodeling

Composite service

Atomic service

QoS,Security,Management&

MonitoringInfrastructureService)

Data

Architecture

&BusinessIntelligen

ce

IntegrationArchitecture

(Enterpris

eService

Bus)

OperationalExisting Application Resources

PackageCustom

Application

Services

Business Processes

Components

Process Choreography

Atomic and Composite Services

4

3

2

1

6 7

Enterprise Components

Custom

Application Package

S

erviceConsumer

ServiceProvider

Consumers

85

JService Portlet WSRP B2B

QoS,Security,Management&

MonitoringInfrastructureService)

Data

Architecture

&BusinessIntelligen

ce


(Enterpris

eService

Bus)


PackageCustom

Application

Services

Business Processes

Components



4

3

2

1

6 7


Custom

Application Package

S

erviceConsumer

ServiceProvider

Consumers

85



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Example: A pattern for successful transition to SOA

Build internal agreement for the investigation

Start with something useful but manageable

Business and IT need to agree on an area of focus

Plan for governance and skills development

Plan to deliver success early and control costs

A useful approach is:

An initial exercise to scope the work and the 1st project

Followed by, concurrently

Governance development

Competency development

An initial, manageable project

In other words patterns arent alwaysalwaystechnical


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Some SOA Anti-Patterns or ways wealready know to get it wrong!

Don't do any performance engineering (Perf)

Do Web Services point to point connectionswithout an ESB (Arch)

Use the data model of an underlyingproduct, rather than the data model thatsupports the business (Arch)

Try to build an SOA with back-level softwareversions (Assemble)

Don't train your team on proper use of thetools and middleware (PM)

Don't inspect the code (PM)

Don't follow modern design practices, e.g.don't use Use Case, express architecture aspatterns, etc (PM)

Plan to deliver the project in a big bang,rather than incrementally (PM)

Don't stress-test the system (Test)

Don't do proper business changemanagement (PM)

Don't understand the number of

interfaces/data formats/user types/.... you'llhave to deal with (Arch)

Don't incorporate performance testing,prototyping during application design (Test)

Don't model business processes (Model)

Don't model in a formal way, i.e. usePowerPoint or Visio instead of a tool thatproduces UML & BPEL (Model)

Don't model the services i.e. don't use SOMAtechniques. (Model)

Don't model the software implementation(Arch)

Write Code from scratch instead ofassembling (Assemble)

Don't have tooling training & support

including both development tools &middleware (PM)

Don't plan testing early; don't include testersearly in the development process (Test)

Dont do performance testing and memoryanalysis for both footprint analysis andmemory leak analysis (Perf)

Don't plan for SOA-style (rapid, frequentlyupdated) deployment and model thedeployment infrastructure (Deploy)

Don't plan to use tooling for deployment(Deploy)

Don't plan/architect for manageability (SysMgt)

Don't involve IT operations early (applies to"deploy" too) (Sys Mgt)

Don't plan for problem determination in acomplex environment, including log analysis& correlation (as does this one) (PD)

Dont plan for light weight monitoring tomonitor system in production (Sys Mgt)

Dont allow for enough development & testinginfrastucture (PM)


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Problem

Equating SOA with Web Services

Symptoms

Replacing existing APIs with Web Services withoutproper architecture

Services are not business aligned

Consequences

Proliferation of Web Services

It is likely those existing systems will not have interfaces that reflect therequirements of the service requestor

Root Cause

Haste: I can take short-cuts and do this SOA stuff quickly and cheaply

Ignorance

Solution

Develop a viable SOA transition plan with defined SOA value proposition Education on SOA vs. Web Services

Apply good Service Modeling (e.g, SOMA)

AntiPattern Name: Web Service = SOA

(also known as Service Proliferation Syndrome)I1


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Web Services can be a part of the answer ...

Service-Oriented Architecture (SOA) is another part

The two are not the same thing:

Most of today's production Web Services systems aren't serviceoriented architectures - they're simple remote procedure calls or point-to-point messaging via SOAP or well structured integration

architectures.

Most of today's production service oriented architectures don'tprimarily use Web Services - they use ftp, batch files, asynchronousmessaging etc. - mature technologies.

Achieving the promoted benefits of SOA and Web Services,requires both

Solution: Education on SOA vs. Web Services

Are Web services the answer?

I1


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Solution: Apply good service modeling method like IBMs SOMA

Ultimately, the goal of SOMA* is to build a SOA.

QoS,Security,M

anagement&

MonitoringInfrastr

uctureService)

Data

Architecture&B

usinessIntelligence


(EnterpriseSe

rvice

Bus)


PackageCustom

Application

Services

Business Processes

Components



4

3

2

1

6 7


CustomApplication

Package

ServiceConsumer

ServiceProvider

Consumers

85


QoS,Security,M

anagement&

MonitoringInfrastr

uctureService)

Data

Architecture&B

usinessIntelligence


(EnterpriseSe

rvice

Bus)


PackageCustom

Application

Services

Business Processes

Components



4

3

2

1

6 7


CustomApplication

Package

ServiceConsumer

ServiceProvider

Consumers

85


>

RealizationDecisions

Specificationof Services, Components, Flows

Identificationof candidateServices, Components, Flows

>

At the heart of SOMA is the identification and specification of services.

I1

* See http://www-128.ibm.com/developerworks/webservices/library/ws-soa-design1/formore information on SOMA


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AntiPattern Name: Chatty Services

Problem

Realize a service by implementing a number of Web Services whereeach communicate a tiny piece of data

Symptoms

Implementation of a large number of services

Consequences

Degradation in performance

Costly development

Burden the consumer with the task of aggregating these services to

realize any benefit Root Cause

Mimic API implementation

Excitement: everythingbecomes a BPEL-defined business service,with no benefit and excessive cost

Solution

Refactor design to combine individual pieces of data in one document

Education on difference between API & service; granularity

Apply Litmus test

Map services back to business goals

R1


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Solution: Refactor Design to combine pieces of data in one document

Do Not Use Fine-Grained Calls

SOAP Engine

Generated SOAPstub

EJB

(controller/model)

Swing

(view/controller)

Java Application

SOAP

over

HTTP

WebSphereApplication Server

Presentation

Layer

Business

Layer

SOAP Engine

Web Service

Examples of badServices

getFirstNamegetLastName

getOfficePhone

Bad: Using WSbetween WASapplication servers(no firewall issues,

fine grainedinteraction)

Source: SOA/WS bootcamp

R1


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Solution: Apply Litmus Test

Support only those that pass the Litmus Tests

SLT1: BusinessAlignment

Services to beExposed

SLT2:Composability

SLT3:

ExternalizedService

Description

Service Model:candidate services

SLT4: RedundancyElimination

S0

S1

S2

S3

Business Goals Candidate Services

SLT 1-1 : Does the service provide arequired unit of business functionality that

supports business processes and goals?

each composed of multiple criteria

From all candidate services,which should we expose?

R1


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Problem

Replacing middleware with point to point web services as an integration approach

Symptoms

Using XML or SOAP over HTTP between Applications

Consequences

Point-to-point integration emerges as the defacto integration pattern

Root Cause

Excitement about using services everywhere

A lack of consideration for the long-term maintenance and evolution of the overallsystem

Solution

Use an intelligent connector such as a Service Bus

Known Exceptions When quick, short-lived integration is required to solve immediate business

problems, but tend to be in production for a long time

Name: Point-to-Point Services

R2


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Solution: Use an intelligent connector such as a Service Bus

Service Bus enables applications to work togethersimply and efficiently to support business needs

AA BB

HH

DD

FF

CC

EE

GG

AA BB

HH

DD

FF

CC

EE

GG

ESBESB

ApplicationsApplications

Tight coupling and complex - Each

application has to be aware of the details ofother applications it has to collaborate with.

Loose coupling and simpler - The service bus

shields each application from the details ofother applications it has to collaborate with.

R2


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Out SOA anti-patterns project

Working with an IBM team to:

Identify SOA anti-patterns

Catalogue them for future reference

Develop education on anti-patterns

And plan to publish our results on IBM DeveloperWorks(http://www.ibm.com/developerworks)


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Wed like to hear from you about SOA anti-patterns

Were very interested in anti-patterns you

observe

Ideally, they will be from real projects

With some sense of the impact of the anti-pattern

If you discover some, send a note to Tony or Paul


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Where to learn more

AntiPatterns: Refactoring Software, Architectures, and Projects inCrisis by William J. Brown, Raphael C. Malveau, Hays W. "Skip"McCormick, and Thomas J. Mowbray (Paperback - Mar 20, 1998)

Service-Oriented Architecture (SOA) Compass : Business Value,Planning, and Enterprise Roadmap (Developerworks) (Hardcover)Norbert Bieberstein, Sanjay Bose, Marc Fiammante, Keith Jones, Rawn

Shah IBM Press

Perspectives on Web Services : Applying SOAP, WSDL and UDDI toReal-World Projects (Springer Professional Computing) (Hardcover) byOlaf Zimmermann, Mark R. Tomlinson, Stefan Peuser ISBN 3540009140

SOA Anti-Patterns article by Steve Jones, CGI

http://www.infoq.com/articles/SOA-anti-patterns

Also check out Steves Blog @ http://service-architecture.blogspot.com/ Search for anti-patterns or patterns


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Where to learn more

AntiPatterns.com www.antipatterns.com

Has a nice briefing on anti-patterns

Rational Software Architect or Rational Application Developer

Check the help file both can support searching for anti-patterns

DeveloperWorks SOA Anti-Patterns page:ww.ibm.com/developerworks/webservices/library/ws-antipatterns/

And many others; search foranti-patterns

IBM Redbooks

http://www.redbooks.ibm.com


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