© 2010 IBM Corporation
FI MU:
SCA and SDO
Tomáš Müller – IT Architekt
tomas_muller@cz.ibm.com
22/11/2010
© 2010 IBM Corporation
Building a smarter planet
2
Agenda
A brief history of SOA
Why SCA makes life simpler
Composing and assembling SCA applications
Code and other details
Customer scenarios
Service Data Objects
Resources
© 2010 IBM Corporation
Building a smarter planet
3
Agenda
A brief history of SOA
Why SCA makes life simpler
Composing and assembling SCA applications
Code and other details
Customer scenarios
Service Data Objects
Resources
© 2010 IBM Corporation
Building a smarter planet
4
A brief history of SOA
When we started with Web services (SOAP over HTTP), we used XML to
move data the idea was to send XML to a URL, invoking a service
synchronously.
Things have gotten more complicated since then:
– Protocols other than HTTP
– Document-style SOAP services instead of RPC
– Asynchronous invocation with JMS
– Encryption, conversations, reliable messaging, WS-*
– Etc.
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A component
When dealing with a component (in an SOA or not),
there are three important pieces of information:
–The interface of the component
–The implementation of the component
–The access method to invoke the component
We’ll consider how we use this information to invoke
components.
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The bad old days
Originally, most components were hardwired into an application:
– The application knew the details of the component’s interface at build time.
– The application accessed the component’s implementation at build time.
– The application knew the details of the component’s access method at build
time.
This worked (and still does), but the application is relatively brittle.
– If the implementation or access method changes, we have to modify our code,
rebuild it, retest it and redeploy it.
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The early days of Web services
SOAP introduced a way to invoke a remote service with an XML envelope.
The SOAP infrastructure built the envelope and sent it to a particular URL;
the SOAP service’s host invoked a service and sent XML back to us.
– The application knew the details of the component’s interface at build time.
– The application did not access the component’s implementation at build
time; the component is invoked at run time by the SOAP infrastructure.
– The application knew the details of the component’s access method at build
time (usually SOAP/HTTP).
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Building a smarter planet
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Next-generation SOA with SCA
An SCA application is even more dynamic:
–The application knows the details of the component’s interface at build
time.
–The application does not access the component’s implementation
at build time; the component is invoked by the SCA invocation
framework.
–The application does not know the details of the component’s
access method at build time; this is also handled by the SCA
invocation framework.
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Building a smarter planet
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osoa.org
SCA and SDO were developed by the Open Service Oriented Architecture group
(osoa.org):
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The specifications work of osoa.org has been turned over to OASIS.
The Open Composite Services Architecture group is being formed now.
– See oasis-opencsa.org for more details.
– Yes, the SCA work has moved to a group named CSA.
– http://www.osoa.org/display/Main/Service+Component+Architecture+Specifications
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A Brief History of SCA
20082007200620052004
consortiaApacheIBM
Apache Tuscany
enters incubation
Apache Tuscany
graduates
OSOA
Founded
Open SCA
submitted to OASIS
Open SCA
collaboration begins
Open
SCA 0.9
V6.1 SOA
FeP Beta
V7.0 SCA
FeP Beta
V7.0 SCA
FeP GA
RAD 7.5.2
SCA GA
2009
RAD 7.5.1
SCA Beta
V6.0
RAD Open SCA
WAS Open SCA
WPS / WID Classic SCA
V6.1 V6.2
V7.0 SCA
v1.0.1
FeP GA
V7.0
RAD 7.5.5
SCA GA
First Public
OASIS Drafts
© 2010 IBM Corporation
Building a smarter planet
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Agenda
A brief history of SOA
Why SCA makes life simpler
Composing and assembling SCA applications
Code and other details
Customer scenarios
Service Data Objects
Resources
© 2010 IBM Corporation
Building a smarter planet
13
Why SCA matters
SCA gives your developers a single programming model for using
services.
As your SOA gets more complicated, your developers have to learn more
and more interfaces.
– In Java alone, you might have EJBs, RMI, JCA, JAX-WS or JAX-RPC.
Similarly, SDO gives your developers a single programming model for
using data sources.
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You're committed to SOA, butYou're committed to SOA, but…… SCA solves these problems:SCA solves these problems:
It's not convenient to convert everything to
a Web service.
You can integrate many kinds of components, not
just Web services.
You want to minimize the learning curve
for your developers.
Your developers don't have to learn the details of
each component, they just connect them without
learning a new API.
As you have more components and data
sources, you'll want to rewire your
applications more often.
When you integrate an SCA component or an SDO
data source, you can replace the component/data
source without changing your code.
Your developers don't understand how to
exploit the power of an SOA.
Your developers focus on reusable business logic.
SCA provides the SOA model and hides the
middleware complexity from them.
Why SCA matters
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Building a smarter planet
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What SCA is
An executable model for assembling services
A simplified component programming model for implementing services
– Write ‘em as BPEL processes, Java POJOs, EJBs, COBOL apps, PHP scripts,
C++ apps…
We won’t focus on this today, but an SCA composite definition includes all
of the services that our composite depends upon.
– Dependency management is much simpler.
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What SCA isn’t
A workflow model
–Use BPEL for that
Web services
–Many SCA implementations will use Web services, but you can create
SCA solutions with no Web services content
Tied to a specific programming language, protocol,
technology, runtime, etc.
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Building a smarter planet
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The SCA specs
There are four parts to the specs:
–The Assembly Model
How to define composite applications
–The Client and Implementation specifications
Java, C++, BPEL
–Binding specifications
How to use access methods – Web services, JMS, RMI-IIOP,
REST…
–Policy Framework
How to add security, transactions, conversations, reliable
messaging, etc. declaratively
© 2010 IBM Corporation
Building a smarter planet
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Agenda
A brief history of SOA
Why SCA makes life simpler
Composing and assembling SCA applications
Code and other details
Customer scenarios
Service Data Objects
Resources
© 2010 IBM Corporation
Building a smarter planet
19
Composition and assembly
How do you package a service so it can be integrated with
other services?
SCA has a consistent model:
–A simple service in SCA is called a componentcomponent.
–Components can be grouped into compositescomposites.
–Components and composites are hooked together with wireswires.
We’ll use SCA diagrams to illustrate these concepts.
All of the definitions and configuration are done in XML.
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Symbols in SCA assembly diagrams
Here are the symbols used in SCA assembly diagrams:
– A green chevron represents a service. This is an entry point to the SCA
component or composite.
– A purple chevron represents a reference. This points to a service
provided by something else.
– A yellow rectangle represents a property. This is a value you can set
when you invoke the component or composite.
– A line represents a wire. This is the connection between a
service reference and the service itself.
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SCA symbols
More symbols:
A rounded rectangle represents a
component. A component can have
services, references and properties.
A large rounded rectangle represents a composite. A composite contains
one or more components. Like a component, it can have services, references
and properties. A composite can also contain a composite.
Component
Composite C
Component
A
Component
B
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Building a smarter planet
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Services and references
A service or a reference has an
interface and a binding.
The interface might be a Java
interface, a WSDL port type, a BPEL
partner link, a C++ class, etc.
The binding defines the access
method. It might be SOAP/HTTP,
JMS, JSON, RMI-IIOP, SCA, etc.
serviceservice
interface
binding
referencereference
interface
binding
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Building a smarter planet
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Properties and implementations
A property has a type and a value.
A component has an implementation;
that’s the code that actually provides
the service.
The implementation might be BPEL,
Java, C++, Spring, etc.
Component
propertyproperty
type
value
implementationimplementation
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Building a smarter planet
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A component
This diagram is a component with
services, references and properties.
servicesservices
referencesreferences
propertiesproperties
type
value
type
value
interface
binding
interface
binding
interface
binding
interface
binding
Component
A
…
…
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Component
A
Component
B
Wiring
wirewire
…
…
Here are two components wired together:
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Component
A
services
references
properties
Component
B
A composite
wire
Composite C…
…
Here are two components grouped together in a composite:
© 2010 IBM Corporation
Building a smarter planet
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Component
A
services
references
properties
Component
B
compositecomposite
referencereference
compositecomposite
serviceservice
Promotion
compositecomposite
propertyproperty
promotedpromoted
referencereference
wirepromotedpromoted
serviceservice
interface
binding
interface
binding
type
value
Composite C…
…
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A
B
Component
D
C
ImplementationImplementation
–– compositecomposite
A composite implementation
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A
B
Component
D
Component
E
C
A composite using another component
…
…
ImplementationImplementation
–– compositecomposite
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Building a smarter planet
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A
…
…
B
Component
D
Component
E
C
Composite F
A composite that includes a composite
ImplementationImplementation
–– compositecomposite
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Building a smarter planet
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Synchronous / Asynchronous Model
SCA provides the ability for services to be called synchronously or asynchronously
Synchronous Model
– Blocking
Client waits for a response
invokeAsync()
Client Service
further
processing
Asynchronous Model
invoke ()
Client Service
further
processing
Synchronous Model
Asynchronous Model
– Non-Blocking
Client doesn’t wait for a response
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Building a smarter planet
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Asynchronous Model
There 3 types of asynchronous invocation models
invokeAsync()
Client Service
further
processing
One Way
invokeAsync()
Client Service
invokeResponse()
further
processing
Deferred Response
invokeAsync()
Client Service
onInvokeResponse()
Request with Callback
further
processing
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Building a smarter planet
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Asynchronous Model
Synchronous vs. Pseudo Synchronous
Synchronous Model
– Blocking
Client waits for a response
invoke ()
Client Service
further
processing
Synchronous Model
invokeAsync()
Client Service
invokeResponse()
further
processing
Deferred Response
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SCA Summary
Implementation
ComponentService Reference
• Java
• Spring
• BPEL
• Composite
…
• C
• C++
• COBOL
…
PropertyInterface
• WSDL
• Java
…
Binding
Interface
• WSDL
• Java
…
Binding
• SCA
• WS
• EJB
• JMS
• JCA
• (JSON-RPC)
• (AJAX)
…
• SCA
• WS
• EJB
• JMS
• JCA
• (JSON-RPC)
• (AJAX)
…
**
*
Policy Set
*
PolicyIntent
*
© 2010 IBM Corporation
Building a smarter planet
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Agenda
A brief history of SOA
Why SCA makes life simpler
Composing and assembling SCA applications
Code and other details
Customer scenarios
Service Data Objects
Resources
© 2010 IBM Corporation
Building a smarter planet
36
An SCA client
Here’s an SCA client that uses SOAP/HTTPSOAP/HTTP:
public class CalculatorClient {
public static void main… {
SCADomain scaDomain =
SCADomain.newInstance("calc.composite");
CalculatorService calcServ =
scaDomain.getService(CalculatorService.class,
"CalculatorServiceComponent");
System…println(calcServ.add(3,2));
scaDomain.close();
}
}
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Building a smarter planet
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An SCA client
Here’s an SCA client that uses RMIRMI:
public class CalculatorClient {
public static void main… {
SCADomain scaDomain =
SCADomain.newInstance("calc.composite");
CalculatorService calcServ =
scaDomain.getService(CalculatorService.class,
"CalculatorServiceComponent");
System…println(calcServ.add(3,2));
scaDomain.close();
}
}
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SCA Annotated Java
package service;
@Remotable
public interface HelloService
{
String hello ( String message );
}
package service;
@Service ( HelloService.class )
public class HelloServiceImpl implements HelloService
{
@Reference public AnotherService anotherService;
String hello ( String message ) {
return anotherService.howdy(message);
}
}
HelloComposite
HelloService
Component
another
Service
Hello
Service
locale
HelloServiceImpl
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SCA Composite XML
<?xml version="1.0" encoding="ASCII"?>
<composite name=“HelloComposite"
xmlns="http://www.osoa.org/xmlns/sca/1.0"
targetNamespace="http://foo.com">
<component name=“HelloServiceComponent">
<property name=“locale">
...
</property>
<service name=“HelloService“>
...
</service>
<reference name=“anotherService“>
...
</reference>
<implementation.java class="services.HelloServiceImpl"/>
</component>
</composite>
HelloComposite
HelloService
Component
another
Service
Hello
Service
locale
HelloServiceImpl
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Building a smarter planet
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Qualities of Service – Intents and Policies
Policies
Composite
<component name=“Component”>
<implementation.java class=“...”/>
<service name=“MyService”>
<interface.java interface=“...”/>
<binding.ws
requires=“authentication” .../>
</service>
</component>
Component
WebService
Binding
Policy
Policy
WS-Policy
Policy Set
requires="authentication"
requires="authentication"
Lookup
Interaction
Intent
Implementation
Intent
Interaction
Intent
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Building a smarter planet
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Bindings
In SCA, a bindingbinding specifies how to access a service.
– Current bindings include WSDL, JMS, JCA and EJBs.
– More bindings are coming all the time at osoa.org.
– Like all of SCA, the binding specification is open, so you can create your own.
Add asynchronous support, conversational support, etc. declaratively:
– <interface.java interface="..."
callbackInterface="...InvoiceCallback"/>
– sca:requires="conversational"
– sca:endsConversation="true"
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Policies
Previous standards efforts, WSDL in particular, didn’t include
how to define general policiespolicies for services.
–Nowadays is situation better due to WS-Policy, WS-PolicyAttachment
SCA gives you a single declarative way to establish policies.
–“This component must provide this level of QoS.”
–“All traffic on this wire must be digitally signed.”
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What’s in the WSDL file?
The data structures
– Defined with XML Schema
The interface
– There’s a method called getStockQuote, it takes a string as input and returns a string
as output
The binding(s)
– SOAP over HTTP
The endpoint(s)
– http://xyz.com:8080/myService
Ideally the bindings and endpoints are in a separate file.
– Unfortunately, that doesn’t always happen.
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What can I do with the WSDL file?
Send a SOAP envelope to a particular service over a particular protocol.
– That’s it.
A Service-Oriented Architecture needs a far more sophisticated way of working
with services.
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Doing more sophisticated things
“Everyone using this service must be authenticated.”
– The WSDL file won’t tell you that.
“Every request sent to this service must be digitally signed.”
– The WSDL file won’t tell you that.
“Any message sent to this service is guaranteed to be delivered.”
– The WSDL file won’t tell you that.
“Particular service ensures specific QoS.”
– The WSDL file won’t tell you that.
“Every message sent to this service must be encrypted.”
– The WSDL file won’t tell you that.
“Every request to this service …”
– SCA tells you everything you need to know.
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The problem with the missing stuff
Without this information, nothing works.
– That’s a big problem.
SCA solves this problem in an elegant way.SCA solves this problem in an elegant way.
– The details we just mentioned are handled by the SCA runtime.
– Those details can be changed without any changes to the client application or the
service.
© 2010 IBM Corporation
Building a smarter planet
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Agenda
A brief history of SOA
Why SCA makes life simpler
Composing and assembling SCA applications
Code and other details
Service Data Objects
Resources
© 2010 IBM Corporation
Building a smarter planet
48
Service Data Objects
SDO gives you a single API to a wide variety of data sources.
You and I as developers focus on CRUD operations, we don’t know or
care what the data source actually is.
– Relational database
– XML database or XML file
– EJB
– Web service
– JCA
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A disconnected interface to many kinds of data sources
Client
Data Access
Service
RDB
XML
DB
EJB
Web
service
JCA
Data object
Data graph
Change summary
JDBC
XPath/
XQuery
Local
XML/HTTP
CCI/
Proprietary
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Accessing data in SDO
I have some data.
I use the data wherever and however it’s stored (RDBMS, XML file, LDAP,
etc.)
I use the most convenient language for CRUD operations on the data
(SQL, XQuery, modified XPath, etc.)
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Service Message Object
ServiceMessageObject
headers context body
SMOHeader
JMSHeader
SOAPHeader correlation transient shared
Mediation primitives process messages as SMOs
The SMO is an extension of the Business Object (BO) structure
It contains: context, message headers, fault details, an array of properties and payload
information
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Service Message Object API
Accessible by API (com.ibm.websphere.sibx.smo.*)
ServiceMessageObject
headers context body
SMOHeader
JMSHeader
SOAPHeader correlation transient shared
ServiceMessageObject
context
transient
ServiceMessageObject smo = (ServiceMessageObject)a_type;
DataObject context = smo.getContext()
DataObject transient = context.getTransientContext();
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SMO – some Java APIs
import com.ibm.websphere.sibx.smobo.ContextType;
import com.ibm.websphere.sibx.smobo.HeadersType;
import commonj.sdo.DataObject;
public DataObject execute(DataObject a_type) {
ContextType context = (ContextType) a_type.get("/context");
HeadersType headers = (HeadersType) a_type.get("/headers");
DataObject body = (DataObject) a_type.get("/body");
return a_type;
}
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Building a smarter planet
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Open Service Component Architecture (Open SCA)
An open, emerging standard programming model
for assembling flexible SOA business solutions
from diverse, reusable service enabled IT assets
RAD 7.5.2+
SCA Tools
WAS 7 SCA
Feature Pack
Develop interfaces
and implementations.
Compose and Wire.
Bindings and Intents.
Define, install and run
contributions on
WebSphere
Application Server.
© 2010 IBM Corporation
Building a smarter planet
55
Agenda
A brief history of SOA
Why SCA makes life simpler
Composing and assembling SCA applications
Code and other details
Service Data Objects
Resources
© 2010 IBM Corporation
Building a smarter planet
56
Resources
The home of everything related to SCA and SDO is osoa.org.
– From here you can find the specs, white papers and tutorials.
The OSOA’s work is moving to OASIS. For more information on the Open CSA project, visit
oasis-opencsa.org.
If you’d like to get involved in the standardization effort, a call for participation has recently
been issued.
The oasis-opencsa.org/specifications page is another great way to find the
specifications and other technical resources.
© 2010 IBM Corporation
Building a smarter planet
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Books
Get Ben Margolis’ book SOA for the
Business Developer: Concepts, BPEL
and SCA.
As of August 2007, this is the best book on
SCA. It covers both the architecture and
the technical details.
Many of the best minds in the SCA world
had a hand in this book.
ISBN 1-58347-065-4
© 2010 IBM Corporation
Building a smarter planet
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developerWorks articles
An overview of Service Component Architecture (2 parts):
– ibm.com/developerworks/webservices/library/ ws-soa-scadev1/ and .../ws-soa-
scadev2/
Building SOA solutions with SCA (4 parts):
– ibm.com/developerworks/websphere/techjournal/0510_brent/0510_brent.html
Java SCA invocation styles:
– ibm.com/developerworks/webservices/library/ ws-soa-scajava/
Using PHP’s SCA and SDO extensions:
– ibm.com/developerworks/webservices/library/ ws-soa-scasdo/
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developerWorks articles
Introduction to Service Data Objects:
– ibm.com/developerworks/java/library/j-sdo/
Build a Web service client with JSF and SDO (Flash demo):
– ibm.com/developerworks/offers/lp/demos/ summary/jsfsdo.html/
SDO 2.0: Create and read an XML document based on an XML Schema:
– ibm.com/developerworks/webservices/library/ ws-sdoxmlschema/
More articles on SCA and SDO are coming all the time.