Why I hate(the hype about) SOA

What is the SOA business case?

SOA

$$$$

Prelude – what is wrong with this code?

public Collection findByPattern(String namePattern) throws SQLException {

Connection conn = DriverManager.getConnection(this.url, this.username, this.password);

Statement stmt = conn.createStatement(); ResultSet rs = stmt.executeQuery(

"SELECT name FROM name_table WHERE name like '" + namePattern + "'");

Collection result = new ArrayList(); while (rs.next()) { result.add(rs.getString(1)); } conn.close(); return result;}

Summary!

• Use connection pooling!• Avoid SQL injection!• Don’t leak the bloody

connections!

Every time you leak a connection…God kills a kitten.

Please: Think of the kitten!

Correct code!

public Collection findByPattern(String namePattern) {

String query = "SELECT name FROM name_table WHERE name like ?";

Object[] params = new Object[] { namePattern };

return jdbcTemplate.query(query, params, new RowMapper() {

public Object mapRow(ResultSet rs, int rowNum) throws SQLException {

return rs.getString(1); } });}

Now: To the agenda of the day!

• The Promise• The Perception• The Failure• BBS architecture• Lessons learned

Is SOA important?

1. “Gartner projects:‘by 2008, more than 75 percent of then-current application

packages either will be natively SOA or will expose SOA interfaces through a wrapping layer of interfaces.’” [InformationWeek]

2. The next (current?) gold rush is in B2B

The incredible shape-changing SOA

Every time you look, it look different!

What is SOA?

• SOA is ”A collection of Services that communicate with each other” [Cryer.com]

• ”[SOA] is an integrated software infrastructure and design approach, leveraging Web computing standards, for delivering business functions as shared and reusable services.” [sun]

• ”SOA is web services” [unattributed]• ”blah, blah,blah, SOA is described, asynchronous,

remote, loosly coupled, orchistrated, standard-based...” [someone fairly smart]

• “Loose coupling”

Fowler on SOA

“I've heard people say the nice thing about SOA isthat it separates data from process, that it combines data and process, that it uses web standards, that it's independent of web standards, that it's asynchronous, that it's synchronous, that the synchronicity doesn't matter.... “

http://martinfowler.com/bliki/ServiceOrientedAmbiguity.html

Three doors marked SOA

Why SOA?

• Business strategy:– Focus on service delivery (agile?)

• Technical strategy:– Focus on integration: New applications quickly, reuse old

applications

– and orchestration: Modelling the business (”even a business person can do it!”)

• Market strategy– Everything that’s good -> everything we sell (this is the SOA trap)

– Consulting services (”non-technical architects”)

– ”Gartner architecture”

The SOA stack

Orchestration

Access Layer

Exposed

Source system

Validate fileSend message

to user[failed]

Wait for duedate

Check credit

[no credit]

Processpayment

Described

The vendor stack (marchitecture)

BPEL, BPMN

JBI

SOAP

Source system

WSDL

A service in the SOA world seems to contain the usual layer upon layer of gunk. At the lowest level we have our meat, the bit that actually does Stuff. This can be EJB or whatnot. Next up we have BPEL (I dozed off briefly so I really don't remember how the two tie together), then above that we have that old dead horse, web services.

- The BileBlog

A service in the SOA world seems to contain the usual layer upon layer of gunk. At the lowest level we have our meat, the bit that actually does Stuff. This can be EJB or whatnot. Next up we have BPEL (I dozed off briefly so I really don't remember how the two tie together), then above that we have that old dead horse, web services.

- The BileBlog

SOA: Understanding your Business

The business of SOA is the business of your business

Your essential business processesYour conceptual information model

Your value proposition

Business-Focus is an Alibi

“We have to find the core value of the business... And we selected Axis as our SOA provider and WebSphere as

our application server.” - J Random SOA Architect

“Huh?!?”- Me

SOA doesn't help!

What does SOA tell me about information modeling? Process modeling? For the enterprise?!

What does SOA tell me to do about this information?

Nothing!

Absurdity of Stateless Microapplications

How much of your application deals with integration with external systems?

The Dangers of Reuse

Building New Legacy on Top of Old Legacy

The Object-Service Impedence Mismatch

Don't transparently expose your domain modelMan-years have been spent on “SOA integration layers”

Orchestration: Example

Validate fileSend message

to user[failed]

Wait for duedate

Check credit

[no credit]

Processpayment

Orchestration: The 21st century CASE tool?

Johannes' Golden Truths about Software Diagrams:

– Understandable diagrams can’t be used to generate

code.

– Diagrams generated from code are mostly useless.

The Complexity and Inadequacy of the “Simple” Object Access Protocol (SOAP)

”The worst possible way of implementing SOA is by using web services”

- Kaare Nilsen, SOA expert, ObjectWare

WS-Adressing, WS-Security, WS-Reliability, WS-ReliableMessaging, WS-Transactions,WS-I-think-I'm-gonna-be-sick

SOA's Failed Potensial: Integration

How can I integrate:• Standards-based

• Reasonably reliably• Inter-enterprise

• Bidirectional• Asynchronously

Final fallacy: Firewalls

• Why do we have firewalls?• Are SOA applications secure?

• So… do we need “SOA firewalls”?

<WEB SERVICES>

Conclusion

• SOA has a fairly substantial cost• Don’t use it if you don’t need it!• You probably don’t need it

• When do you need it?– If you are Amazon, ebay, or google– If your customers are paying you for it

BBS architecture

Slides not to be published

BBS architecture

• Background: Replacing mainframe batch applications written in COBOL with Java

• Requirements– Robustness– Security– Scability (roughly quantified)– Operatability (quanitified)– Maintainability (quantified)

At a glance

Mottak ProcessingTriggered

actionRequest

Processing chain

Response Distribution

billingaccess control

domain modelrepositoryentityRepository

Database

external domain repository

Processing

otherdependency

Persistence

receipt

Service-Repository

WebController

View

onlinebilling

access control

Workflow: Asynchronous Entity Service

Response Processingqueue

Database

queue

Database

Response Processing

Dependency Injection

Incoming File Channel

File Adapter(infrastructure)

Icky file management stuff(ick! Ick!)

Claim check queue

FileDatabase

Adapter

File destination

Service Framework

Application service

File destination

Report service

Adapter

Integration queu

e

Print and distribution

Outgoing file adapter

External subsystem

Icky fileprotocols

Filedestination

How do we get the SOA benefits?

• Integration– Standardized protocols (Bankens Standardiseringskontor,

cirka 1990…)

• Orchestration– Remove temporal coupling– Simple, static workflow– Driven by single, simple events

• Reuse– Code and design reuse (patterns)– Primarily in-process – Rocket science: method invocations…

The SOA doors

SOA is everything that is good

SOA is everything we sell

SOA is integration

Conclusion

• Your most pressing architectural risks are not solved by SOA

• SOA’s vision is not new• The SOA stack may not be your best bet• The vision can be archived by old technology with a new twist

for real benefits

• Build simple, robust, and for today!

• SOA might not be wrong for you, but I recommend ignoring it until you know you need it.