1. © IBM Corp, 2010.
Graham Charters | IBM
SOA Flexibility with OSGi
Remote Services and the
Service Component
Architecture

2. © IBM Corp, 2010.
SOA Flexibility with OSGi Remote Services
and the Service Component Architecture
...including a demo...or two

3. © IBM Corp, 2010.
SOA Design Principles
• Service-based for simple interaction patterns
• Loose Coupling so components need not know
implementation details and can be bound late
• Separation of Concerns so developers can focus on
immediate task
• Composition and re-composition of assets
• Heterogeneity to re-use what we already have

4. © IBM Corp, 2010.
Flexibility
• What might we want to be flexible?
• Choice of Service Provider?
• Choice of Binding?
• Qualities of Service?
• All of the above

5. © IBM Corp, 2010.
Framework Framework
Remote Services
Service
Provider
Bundle
Service
Provider
Bundle
Service
Consumer
Bundle
Service
Consumer
Bundle
Pass-by-value
Latency
Unreliable
Pass-by-value
Latency
Unreliable
NetworkNetwork

6. © IBM Corp, 2010.
Framework Framework
Distribution Provider
Service
Provider
Bundle
Service
Provider
Bundle
Service
Consumer
Bundle
Service
Consumer
Bundle
Distribution
Provider
Distribution
Provider
Distribution
Provider
Distribution
Provider
Remote Services
Provider Configuration
Remote Services
Provider Configuration
endpoint
Remote Services
Client Configuration
Remote Services
Client Configuration
NetworkNetwork
to endpoint
Pass-by-value
Latency
Unreliable
Pass-by-value
Latency
Unreliable

7. © IBM Corp, 2010.
Services Properties
Framework Framework
Service
Provider
Bundle
Service
Provider
Bundle
Service
Consumer
Bundle
Service
Consumer
Bundle
service.exported.interfaces
service.intents
service.exported.intents
service.exported.intents.extra
service.exported.configs
<other service properties>
service.exported.interfaces
service.intents
service.exported.intents
service.exported.intents.extra
service.exported.configs
<other service properties>
objectClass
service.intents
service.imported.configs
service.imported
<other service properties>
objectClass
service.intents
service.imported.configs
service.imported
<other service properties>
endpoint
NetworkNetwork
to endpoint

8. © IBM Corp, 2010.
Intents
• Describe an abstract requirement or capability
– Separation of concerns – requirement/capability
independent of implementation
– Implementation is a deployment choice
• Three properties
service.intents – provided by the service (local and remote)
service.exported.intents – statically configured for remote
service.exported.intents.extra – admin configured for remote
• Inspired by SCA intents, examples include
– confidentiality, integrity, atLeastOnce, atMostOnce, SOAP.v1_1,
etc.

9. © IBM Corp, 2010.
Configuration Types
• Identifies a type of Distribution Provider specific
configuration
• Use reverse domain name scheme to avoid conflict
• Property naming convention used for extra config
service.exported.configs = com.acme.config
com.acme.config.host = …
com.acme.config.port = ...

10. © IBM Corp, 2010.
OSGi Remote Service Summary
• Standardizes basic metadata for distribution
– Remote interfaces
– Default invocation semantics
– Place to hang QoS requirements (intents)
– Place to hang distribution provider configuration
• However...
– Distribution configuration details left to distribution
provider
• Encryption, signing, protocols, ...
– Full configuration not portable
– No standard way to configure for interoperability

11. © IBM Corp, 2010.
…enter the SCA Configuration Type
• Standardizes detailed distribution provider
configuration
– Leveraging SCA Bindings, Policy specifications
• Fully Portable
• Interoperable through interoperable bindings
and policy (e.g. WS-*)

12. © IBM Corp, 2010.
Service Configuration
• Remote Service properties unchanged
service.exported.interfaces = ...
service.exported.intents = …
etc...
• Defines a configuration type following
Remote Services spec
service.exported.configs = org.osgi.sca
org.osgi.sca.bindings = <bindings to use>

13. © IBM Corp, 2010.
SCA Bindings
• Configuration for protocols and technologies
• Standard bindings (OASIS)
– Web services, JMS, JCA
• Extensible (e.g. Apache Tuscany)
– JSON, JSON-RPC, Atom, RMI, EJB, ...
<binding.ws name="OrderServiceBinding"
uri="http://localhost:8086/OrderService" />
<binding.ws name="OrderServiceBinding"
uri="http://localhost:8086/OrderService" />

14. © IBM Corp, 2010.
SCA Policy
• Intents: an abstract
requirement or capability
(sound familiar?)
• PolicySet: an implementation
of an intent (using a policy
language e.g. WS-Policy)
• Ideally the distribution provider
is pre-configured so you never
need to specify the details
PolicySetPolicySet
IntentIntent
<sca:policySet name="Encrypted"
provides="acme:protection"
appliesTo="sca:binding.ws"
xmlns:wsp="..." xmlns:sp="...">
<wsp:Policy>
<wsp:ExactlyOne>
<sp:Basic256Rsa15 />
<sp:TripleDesRsa15 />
</wsp:ExactlyOne>
</wsp:Policy>
</sca:policySet>
<sca:policySet name="Encrypted"
provides="acme:protection"
appliesTo="sca:binding.ws"
xmlns:wsp="..." xmlns:sp="...">
<wsp:Policy>
<wsp:ExactlyOne>
<sp:Basic256Rsa15 />
<sp:TripleDesRsa15 />
</wsp:ExactlyOne>
</wsp:Policy>
</sca:policySet>

15. © IBM Corp, 2010.
<sca-config ...>
<binding.ws name="OrderServiceBinding"
uri="http://localhost:8086/OrderService" />
...
</sca-config>
<sca-config ...>
<binding.ws name="OrderServiceBinding"
uri="http://localhost:8086/OrderService" />
...
</sca-config>
Configuration Bundle
Framework
Service
Provider
Bundle
Service
Provider
Bundle
service.exported.configs = org.osgi.sca
org.osgi.sca.bindings = OrderServiceBinding
service.exported.configs = org.osgi.sca
org.osgi.sca.bindings = OrderServiceBinding
Configuration BundleConfiguration Bundle
Distribution
Provider
Distribution
Provider
Extends
Bindings, Policy, Intents
endpoint
SCA-Configuration: ...

16. © IBM Corp, 2010.
Demo (Application Bundles)
OSGi Framework
FGDBank.webFGDBank.web FGDBank.bizFGDBank.biz
FGCBank.apiFGCBank.api
FGDBank.
chequingAccount
FGDBank.
chequingAccount
FGDBank.
lineOfCreditAccount
FGDBank.
lineOfCreditAccount
OSGi Framework
FGDBank.creditCheckFGDBank.creditCheck

17. © IBM Corp, 2010.
Demo (adding Config Bundles)
OSGi Framework
FGDBank.webFGDBank.web FGDBank.bizFGDBank.biz
FGCBank.apiFGCBank.api
FGDBank.
chequingAccount
FGDBank.
chequingAccount
FGDBank.
lineOfCreditAccount
FGDBank.
lineOfCreditAccount
OSGi Framework
FGDBank.creditCheckFGDBank.creditCheck
FGDBank.chequing
AccountBindings
FGDBank.chequing
AccountBindings
FGDBank.IineOfCredit
AccountBindings
FGDBank.IineOfCredit
AccountBindings
FGDBank.creditCheck
Bindings
FGDBank.creditCheck
Bindings

18. © IBM Corp, 2010.
Demo runtime – EquiTuscAries
• Head of Apache Aries + Head of
Apache Tuscany on Eclipse Equinox
• Fingers cross this will work...

19. © IBM Corp, 2010.
SCA Configuration Type Summary
• Standardizes fully-portable distribution
provider configuration
• Based on SCA Bindings and SCA Policy
• Configuration for interoperability through
interoperable binding

20. © IBM Corp, 2010.
So where's the Flexibility?
• Configuration Bundle lifecycle determines
– Endpoint availability
– Protocol/technology choice
– Quality of Service configuration
• Service properties determine
– Quality of Service choice
– Binding choice
• All configurable without changing the service
client or provider code

21. © IBM Corp, 2010.
But there's more to SCA than
bindings and policy...

22. © IBM Corp, 2010.
What is SCA?
• Heterogeneous component assembly
• Synchronous, asynchronous, event processing
• Pluggable communications protocols
• Think Blueprint Service or Spring Framework
only with bigger components implemented using
different stuff and able to talk to other different
stuff...

23. © IBM Corp, 2010.
SCA Overview
Composite A
Component
AService
Binding
Web Service
SCA
JCA
JMS
EJB
…
Binding
Web Service
SCA
JCA
JMS
EJB
…
Component
B
Service
- Java interface
- WSDL PortType
Reference
- Java interface
- WSDL PortType
Wire
PromotePromote
Reference
Implementation
- Java
- BPEL
- JEE
- Spring
- Composite
…

24. © IBM Corp, 2010.
Where does OSGi fit?
• Apache Aries and WebSphere Application Server define an
OSGi Application Concept
• OSGi Applications fit well as an SCA Component
implementation
• Re-use OSGi Remote Services metadata or have SCA provide
configuration externally for even greater flexibility
– SCA looks like a Distribution Provider to OSGi
BundleBundle
BundleBundle
BundleBundle
Component
Application
Customer
Component
(Widget) Warehouse
Component
(JEE)

25. © IBM Corp, 2010.
Demo (OSGi Application View)
FGDBankApp
FGDBank.webFGDBank.web FGDBank.bizFGDBank.biz
FGCBank.apiFGCBank.api
FGDBank.
chequingAccountApp
FGDBank.
chequingAccount
FGDBank.
chequingAccount
FGDBank.
lineOfCreditAccountApp
FGDBank.
lineOfCreditAccount
FGDBank.
lineOfCreditAccount
“shared” bundle
FGDBank.
creditCheckApp
FGDBank.creditCheckFGDBank.creditCheck

26. © IBM Corp, 2010.
Demo (SCA Assembly View)
FGDBankAppSCA
FGDBankApp
FGDBank.chequingAccoutAppSCA
FGDBank.
chequingAccountApp
FGDBank.creditCheckAppSCA
FGDBank.creditCheckApp
FGDBank.lineOfCreditAccountAppSCA
FGDBank.
lineOfCreditAccountApp

27. © IBM Corp, 2010.
Summary
• OSGi Remote Services provides basic metadata for Distributing
OSGi services
• SCA Configuration Type provides detailed portable distribution
configuration
• SCA leverages OSGi Remote Service metadata to integrate
OSGi applications
– SCA acts as an OSGi Distribution Provider
• Distribution is non-invasive to client and service provider code
and therefore enables flexible assembly and re-use

28. © IBM Corp, 2010.
Useful Links
• Enterprise OSGi R4 V4.2 Specification
– http://www.osgi.org/Download/Release4V42
• Apache Aries
– http://incubator.apache.org/aries/
• Apache Tuscany
– http://tuscany.apache.org/
• WebSphere Application Server OSGi Applications
– http://www-01.ibm.com/software/webservers/appserv/was/featurepacks/osgi/