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Seminar on Service Oriented Architecture. Composite Services Architecture (CSA). Sources: www.osoa.org “SOA for the Business Developer” by Margolis “Introducing SCA” by Chappell. Composite Services Architecture (CSA). - PowerPoint PPT Presentation
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1SOA Seminar
Seminar on Service Oriented Architecture
Composite Services Architecture (CSA)Sources:
www.osoa.org“SOA for the Business Developer” by Margolis“Introducing SCA” by Chappell
2SOA Seminar
Composite Services Architecture (CSA)
• In March 2007, Composite Services Architecture (CSA) is passed on to OASIS by the Open Service Oriented Architecture collaboration.
• CSA is supported by BEA, IBM, Oracle, Sun, Tibco, Red Hat and others.
• CSA Consists of SCA (Service Component Architecture) and SDO (Service Data Objects).
• Implemented by IBM WebSphere, Oracle, Red Hat, Tibco, and the open source Apache Tuscany.
• Describes how to compose and deploy applications supporting SOA.
• Decouple business logic from details associated with the call on that logic.
• Introduces The Service Component Definition Language (“skiddle”) to describe composites.
3SOA Seminar
SCA Specifications (1)
• Assembly model defining composites, components, references and wires
• Policy Framework allowing analysts to define constraints, capabilities and qualities of service expectations
• Bindings allowing heterogeneous transports (SOAP, JMS, IIOP,etc.)
• Java annotations, API’s and component implementation (@Remotable)
• C++, BPEL, PHP, EJB and Spring for SCA
4SOA Seminar
SCA Specifications (2)
• The Assembly model defines composites, components, references and wires.
The assembly model defines how components are combined into composites and are packaged and deployed as services. We specify such details as encryption, authentication and
queuing outside of the business service.
5SOA Seminar 5Master of Information System Management
SCA Specifications (3)
• The Policy Framework allows analysts to define constraints, capabilities and qualities of service expectations.
WSDL does not support the description of policies.The SCA Policy Framework uses WS-Policy and WS-PolicyFramework to describe policies for service users.
From www.osoa.org:Business value: The ability to define policies outside the services themselves lets administrators set and change the policies without changing code. It also means administrators know their policies are implemented globally.
6SOA Seminar 6Master of Information System Management
SCA Specifications (4)
• Bindings allow heterogeneous transports (SOAP, JMS, IIOP,etc.) to be used.
Bindings specify the mechanisms to access particular kinds of components. Applications built with SCA can use Web services, JMS, JCA and EJBs. (More bindings are on the way from osoa.org.) As you would expect, the bindings can be defined outside the code itself.Business value: The bindings provided in SCA allow developers to use a wide variety of services without knowing the details of how those services are accessed. With the bindings external to the code, the bindings can be changed without changing the code.
From www.osoa.org:
7SOA Seminar
SCA Components (1)
Implemented in BPEL, Java, C++, etc.
This may also be a composite.
services
properties
references
<component> <implementation> <service> <binding>… <property> <reference> <binding>…</component>
8SOA Seminar
SCA Components (2)
Implemented in BPEL, Java, C++, etc.
This may also be a composite.
services
properties
references
<component> has a name and list of policy intents <implementation> has a name and an implementation type <service> has an interface and a binding <property> names and values to be passed in <reference> includes a binding</component>
9SOA Seminar
SCA Components (3)
Business logic Implementation
services
references
Property values passed in at runtime.
Operationsavailable toclients.
Other services this client depends on.
Dependency injection: The SCA runtime performs a lookup for thereference. The business logic need not be concerned with how theother service is accessed.Nor is the business logic developer concerned with how this componentis accessed. That detail is specified as a binding - outside of the businesslogic.
10SOA Seminar
SCA Components (4)<composite>
<service> <property> <reference> <wire> <component> <implementation> <service> <property> <reference> </component>
<more components > :</composite>
A component is the atom of an SCA application. It lives within a composite.
A component is a configured implementation.
SCA is language agnostic.
SCDL defines how the componentinteracts with the outside world.
A component might talk to othercomponents within its own domain oroutside of its own domain.
An SCA runtime knows what to do withthis.
11SOA Seminar
SCA Components Quiz (1)<component name=“Component1”> <implementation.java class=“services.examples.Calc”> <service name=“AS”> <binding.ws uri=http://www.myserve.com/service/> </service> <property name=“initValue”>0</property> <reference name=“MonitorService”> <binding.ws uri=http://www.etc.com/service/> </reference> </component>
What can we say about the component beingdefined?
12SOA Seminar
SCA Components Quiz (2)<component name=“Component2”> <implementation.bpel process=“CalcProcess”> <service name=“AS”> <binding.ws uri=http://www.myserve.com/service/> </service> <property name=“initValue”>0</property> <reference name=“MonitorService”> <binding.ws uri=http://www.etc.com/service/> </reference> </component>
And this one?
Other bindings include binding.jms and binding.ejb.
13SOA Seminar
SCA Composites (1)
services
properties
references
wire wire
14SOA Seminar
SCA Composites (2)
services
properties
references
wire wire
Components
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SCA Composites (3)
services
properties
references
wire wire
Perhaps implementedin BPEL.
Perhaps implementedin Java.
16SOA Seminar
SCA Composites (4)
services
properties
references
wire wire
How this communicationis done may be left up to the SCA runtime.
These may run on different machines.
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SCA Composites (5)
services
properties
references
wire wire
reference
service
A wire is an abstract representationof the relationship between a reference and some service thatmeets the needs of that reference.
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SCA Composites in “Skiddle”
<composite>
<service> <property> <reference> <wire> <component> <implementation> <service> <property> <reference> </component>
<more components > :</composite>
Contains binding information.
Contains binding information.A wire connects components.Components may live in differentprocesses or on different machines.
A composite solves a business problem.
Components might be written in Java,BPEL or some other language.
A composite may be used as a componentin a higher-level assembly.
A composite does not cross domain boundaries.
19SOA Seminar
SCA Domains
• Contain one or more composites.• May cross machine and process
boundaries.• Are each managed by a single
group of people.• Run on a single vendor’s SCA
runtime.• Place no restrictions on how
internal communication is done.
20SOA Seminar
SCA Bindings
• Bindings specify how one component communicates with another.
• A single component may have multiple bindings.
• The use of bindings separate what a component does from how we communicate with it.
21SOA Seminar
SCA Services, References & Properties
• Components expose one or more services.• How the services are described depends
on the technology.• Descriptions for clients in other domains
would typically use interoperable WSDL.• A service provides some number of
operations.• If a component uses other services then
these are described with references.• Properties are values taken from the SCDL
and describe the world to the component.
SCA Summary• From www.osoa.org:
• As your SOA becomes more complex, you'll need the simplicity and flexibility of SCA. The Service Component Architecture helps you:
• Save time and money - A simpler API means a shorter learning curve with fewer errors.
• Enable and encourage reuse - Developers can create composites that perform useful functions. SCA makes it easy to use and reuse them.
• Manage your system - Because policies can be defined outside the code that performs the service, you can change the policies without changing the code.
22SOA Seminar
23SOA Seminar
Service Data Objects (SDO)
• A specification to unify data programming across heterogeneous data sources.
• May be used by SCA to interact with data sources.
• Several competing approaches exist in the Java persistence API space.
• SDO is more mature and general than Java’s Persistence API (JPA).
• SDO is not Java specific, e.g., has support in PHP.
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Service Data Objects (SDO)
• Typical data sources include: JDBC Entity EJB’s Web Services XML sources JMS messages Enterprise Information Systems through J2EE Connector Architecture
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Goals of SDO
• To simplify the life of the application developer.• To provide new opportunities for tools
and frameworks to work with a wide variety of data sources.
• Thus, we see support for both static (account.getBalance()) and dynamic (resultSet.getFloat(“BALANCE”)) data API’s. One for programmers the other for tools.
26SOA Seminar
SDO Architecture (1)
• Based on disconnected data graphs and optimistic concurrency (OC).
clientData Access Service (DAS)
Data Source
OC: If any change occurs on the backend while the client is makingchanges, a subsequent attempt toupdate must be rejected. The clientwould then need to take appropriate action. Pessimistic concurrency locks resources. OC is preferred if concurrentaccess is rare.
One DAS maywork withRDBMS and another maywork withXML etc.
The DAS creates the graph of dataobjects.
27SOA Seminar
SDO Architecture(2)• Data Objects hold the data and metadata.• Data Objects have rich relationship support.• The Data Graph logs every change to the data.
clientData Access Service (DAS)
Data Source
• Xpath is used to dynamically
select data objects from the data graph.
28SOA Seminar
SDO Architecture(3)• Data Access Services come in various forms:
client
Relational Data
AccessService
EJB Data Access Service
XML Data Access Service
SCA and JBI• See article by Mike Edwards (IBM) at http://www.osoa.org/display/Main/Relationship+of+SCA+and+JBI
• How does SCA differ from JBI?• JBI stands for Java Business Integration• JBI defines a set of of Service Provider Interfaces for
middleware providers to implement if they want to install new service engines (SCA implementation types) or binding components (SCA bindings).
• SCA is for developers, assemblers and deployers of business services. SCA says nothing about how new implementation types or new bindings might be introduced.
• JBI is for middleware vendors. SCA is for business developers.
29SOA Seminar
SCA and JBI Bottom Line• See article by Mike Edwards (IBM) at http://www.osoa.org/display/Main/Relationship+of+SCA+and+JBI
“JBI should be considered a Java technology that potentially helps middleware vendors to implement SCA. JBI and SCA do not compete or conflict with each other.”
“SCA, on the other hand, allows multiple technologies to be used to implement services( e.g. Java, BPEL, C++) and multiple bindings to communicate with services (e.g. web services, JMS).”
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