SCA: Flexible and Agile Composition of Distributed SOA Applications

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SCA Flexible and Agile Composition of
Distributed SOA Applications
www.oasis-open.org
Mike Edwards - IBM Hursley Lab, England
Simplicity, Consumability, Agility
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Agenda

• Customer scenario
• SCA overview
• SCA details
• Web 2.0 SCA

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Customer scenario

• A bank implemented a pilot project using SCA and
  SDO
• Growing presence in multiple countries
• Wide variety of technologies in use
• Unix Mid Range, AS400, Mainframe, WebSphere /
  WebLogic, Java / .NET, Kitchen Sink
• The group that sponsored the project is
  responsible for Retail Banking Channel
  Presentation and Service Tier
• Rollout of "Official" SOA strategy
• Set the standards for future initiatives within
  the Bank

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Problem Lack of an enterprise-wide SOA framework

• Proliferation of standards and frameworks
• WS-
• Apache SOAP
• Apache AXIS
• XFire
• IBM Web Services Runtime
• Open source frameworks
• Custom built frameworks
• Never ending cycle of migration and reinventing
  the wheel
• Hurting time to market
• Extra costs to maintain
• Need to simplify service development
• Allow service developers to focus on business
  logic
• Make it easy to reuse services

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Key features of the customers infrastructure

• Service Platform WS-I Basic compliant,
  Java-based client invocation and service endpoint
  framework
• Expose services using different interfaces,
  multiple invocation mechanisms (local,
  WSDL/schema, JMS...)
• Service Lifecycle Events Logging, Caching,
  Business Validation, Error Handling...
• Enable POJO programming model for developing
  services
• Requirements, design, development, operational
  and other processes to support SOA approach

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Key features of the customers infrastructure

• Enterprise adoption
• Development, Deployment, Operational, Governance
  Capabilities
• Service development training material
• Collaborative, shared ownership
• All process, technical and other documentation
  placed in a Wiki, open to contributions
• Improvements took place using an "open source"
  model, allowing any resource to contribute to
  code base, with select group controlling commits

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Thin Client Browser / AJAX
Rich Client UI
IVR
Mobile
Web User Interface Components
Service Platform
Different Heterogeneous Backend Systems
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Layers in the infrastructure

• Access layer
• Spring Framework (AOP, IOC) for applications,
• IFX (Interactive Financial Exchange) for schemas
  and interfaces
• SCA/SDO to access services data sources
• Middle tier
• WebSphere, Spring, JMS
• Services built with SCA assembly model
• IFX data packaged with SDO
• Back end
• The usual suspects (transaction servers,
  mainframes, relational databases, packaged apps)

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Infrastructure based on three open standards

• SCA/SDO
• Becoming widely recognized as a standard
• Support for multiple bindings configurable at
  runtime
• Configuration based assembly of components using
  dependency injection
• Components can be implemented using many
  languages/technologies
• Multiple implementations to choose from

• Interactive Financial Exchange (IFX)
• Standards-based data exchange format for business
  banking
• Spring
• AOP for lifecycle events (Logging, Caching, Error
  Handling, etc.)
• Finer grained dependency injection

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Selling SCA

• SCA, SDO enabled business to build service
  platform with low barriers to adoption
• POJO components
• Evolutionary SOA adoption
• Open communities
• Some original applications used POJOs. To moving
  to an SOA, applications changed to use SCA
  services
• For now, the SCA services are just POJOs. When
  they need to use other kinds of (SCA) services,
  they dont have to make any changes

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The future

• Future enhancements to infrastructure will take
  advantage of wider features of SCA and SDO
• WS-Policy/WS-Security
• Other implementations (COBOL)
• Asynchronous invocation (JMS)
• Presentation layer (AJAX, JSONRPC)
• BPEL orchestration
• Using these features will require very few
  changes (if any) to their applications

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Agenda

• Customer scenario
• SCA overview
• SCA details
• Web 2.0 SCA

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What SCA is

• executable model for assembling services
• composites provide language to compose and
  configure service components
• handles service dependencies
• Simplified component programming model for
  implementing services
• BPEL processes, Java POJOs, EJBs, COBOL, PHP
  scripts, C apps, JavaScript AJAX, XSLT
• Late binding of policy and communication methods,
  with distributed deployment model

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Why SCA makes life simpler

• One way to look at SCA is that it takes details
  of
• access methods and endpoints
• implementations and configuration
• policy such as encryption, authentication
• and moves them into middleware layer
• Application developers write business logic code
  that actually builds value for your organization
• details of using services are handled by SCA
• late binding as details change, applications
  (and developers who wrote them) arent affected
• "no plumbing in the code"

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Why SCA makes life simpler

• SCA gives developers a single programming model
  for using servicesfor all aspects of service
  lifecycle
• Construction
• Assembly
• Deployment
• As your SOA gets more complex, developers have to
  learn more and more interfaces
• In Java alone EJBs, RMI, JCA, JAX-WS, JMS
• Similarly, SDO gives developers a single
  programming model for using data sources

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SCA is not

• tied to a specific programming language,
  protocol, technology, runtime
• a workflow model
• Use BPEL for that
• Web services
• SCA can access local objects, avoiding the
  overhead of Web services
• of course, many SCA applications will use Web
  services
• an ESB
• to program an ESB from scratch, SCA fits
  perfectly
• but SCA is more than an ESB

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SCA assembly
RMI/IIOP
AccountsComposite
External Banking Reference
Payments Component

Payment Service

OrderProcessing Component


Order Processing Service

Java EE

Accounts Ledger Component

BPEL
SOAP/HTTP
Multi-level composition
WarehouseComposite
External Warehouse Reference
Warehouse Broker Component

Mixed - technologies - app locations
Warehouse Component
Warehouse Service





JMS
Shipping Reference
C
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Agenda

• Customer scenario
• SCA overview
• SCA details
• Web 2.0 SCA

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Simple Example
bigbank.accountcomposite
Reference
StockQuote
Service
AccountService
Service
Service
Component
AccountService
AccountService
AccountData
AccountData
Service
Service
Component
Component
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ltcomposite xmlns"http//www.osoa.org/xmlns/sca/1.
0" name"bigbank.accountcomposite"
gt ltcompositegt
ltservice name"AccountService"
promote"AccountServiceComponent"gt
ltinterface.java interface"services.account.Accoun
tService"/gt ltbinding.ws
port"http//www.example.org/AccountService
wsdl.endpoint(AccountService/AccountServiceSO
AP)"/gt lt/servicegt
ltcomponent name"AccountServiceComponent"gt
ltimplementation.java class"services.account.
AccountServiceImpl"/gt ltreference
name"StockQuoteService"/gt ltreference
name"AccountDataService"
target"AccountDataServiceComponent/AccountDataSer
vice"/gt ltproperty name"currency"gtEUROlt/pr
opertygt lt/componentgt
bigbank.accountcomposite
StockQuote
Reference
Reference
StockQuote
StockQuote
Service
Service
ltcomponent name"AccountDataServiceComponent"gt
ltimplementation.bpel processQName"/gt
ltservice name"AccountDataService"gt
ltinterface.java interface"services.accountdat
a.AccountDataService"/gt lt/servicegt
lt/componentgt
AccountService
Service
Component
AccountService
AccountData
Service
Component
ltreference nameStockQuoteService"
promote"AccountServiceComponent/StockQuoteService
"gt ltinterface.java interface"services.sto
ckquote.StockQuoteService"/gt ltbinding.ws
port"http//example.org/StockQuoteService
wsdl.endpoint(StockQuoteService/StockQuoteServ
iceSOAP)"/gt lt/referencegt
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Java Implementation Example Service Interface
Interface is callable remotely eg. as a Web
service
package org.example.services.account _at_Remotable
public interface AccountService public
AccountReport getAccountReport(String
customerID)
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Java Implementation Example (1)
package org.example.services.account import
org.osoa.sca.annotations. _at_Service(interfaces
AccountService.class) public class
AccountServiceImpl implements AccountService
private String currency "USD" private
AccountDataService accountDataService
private StockQuoteService stockQuoteService
public AccountServiceImpl(
_at_Property("currency") String currency,
_at_Reference("accountDataService")
AccountDataService dataService,
_at_Reference("stockQuoteService") StockQuoteService
stockService) this.currency
currency this.accountDataService
dataService this.stockQuoteService
stockService
Annotation for the service offered by this class
Constructor with annotations for injected
property and references
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Java Implementation Example (2)
public AccountReport
getAccountReport(int customerID)
throws AccountDataUnavailableException
AccountReport accountReport
accountDataService.getAccountReport(customerID)
ListltStockgt stocks
accountReport.getStocks()
ListltStockValuesgt stockValues
stockQuoteService.getValues( stocks, currency
) accountReport.setStockValues(
stockValues ) return
accountReport // end class
Get the basic account report using the account
data service
Obtain up to date stock values using the stock
quote service
Update the account report with the latest stock
values
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Associating Policies with SCA Components

• Intents and/or policySets can be associated with
  any SCA component
• At deployment time intents map to Policies
  contained in policySets
• Examples attaching intents

Confidentiality applied to any use of the service
ltservice name"AccountService promoteAccountSer
viceComponent requires"scaconfidentiality"gt
ltinterface.java interface"services.account.Acc
ountService"/gt ltbinding.ws port"http//www.big
bank.com/AccountService wsdl.endpoint(Accou
ntService/AccountServiceSOAP)"/gt lt/servicegt ltrefer
ence name"StockQuoteService
promoteAccountServiceComponent/
stockQuoteServicegt ltinterface.java
interface"services.stockquote.StockQuoteService"/
gt ltbinding.ws port"http//www.quickstockquote.
com/StockQuoteService wsdl.endpoint(StockQu
oteService/StockQuoteServiceSOAP)
requiresscaconfidentiality/gt lt/referencegt
Confidentiality applied to Web service binding
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Policy Sets

• Policy Sets contain concrete Policies

ltpolicySet name"scauserNameTokenHashPassword"
provides"scaauthentication"
appliesTo"scabinding.ws"gt ltwspPolicygt
ltspSupportingTokengt ltwspPolicygt
ltspUserNameTokengt ltwspPolicygt
ltspHashPasswordgt lt/wspPolicygt
lt/spUserNameTokengt lt/wspPolicygt
lt/spSupportingTokengt lt/wspPolicygt lt/policySetgt
defines intents provided
what this policy applies to
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Agenda

• Customer scenario
• SCA overview
• SCA details
• Web 2.0 SCA

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Web 2.0 Composite Applications
Web Server
implementation.widget
HTML JS
Services
implementation.widget- HTML Javascript with
SCA reference wiring- Access services from
scripts with async
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Web 2.0 Gadgets meet SCA
Web Server
implementation.widget
Gadget HTML JS
Services
implementation.widget- HTML Gadgets with SCA
reference wiring- Access services from scripts
with async - Link to other on-screen gadgets
other Widgets
can be any gadget supporting mashup technology
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HTML JS SCA Implementation

• Store Implementation
• lthtmlgt
• ltheadgt
• lttitlegtStorelt/titlegt
• ltscript type"text/javascript" src"store.js"gtlt/sc
  riptgt
• ltscript language"JavaScript"gt
• //_at_Reference
• var catalog new Reference("catalog")
• //_at_Reference
• var shoppingCart new Reference("shoppingCart")
  
• //_at_Reference
• var shoppingTotal new Reference("shoppingTotal"
  )
• function catalog_getResponse(items)

Defines references to services
Call reference operations
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HTML JS Component Configuration

• Store Configuration
• ltcomposite name"store" gt
• ltcomponent name"Store"gt
• lttimplementation.widget location"uiservices/st
  ore.html"/gt
• ltservice name"Widget"gt
• lttbinding.http uri"/ui"/gt
• lt/servicegt
• ltreference name"catalog" target"Catalog"gt
• lttbinding.jsonrpc/gt
• lt/referencegt
• ltreference name"shoppingCart"
  target"ShoppingCart/Cart"gt
• lttbinding.atom/gt
• lt/referencegt
• ltreference name"shoppingTotal"
  target"ShoppingCart/Total"gt
• lttbinding.jsonrpc/gt
• lt/referencegt
• lt/componentgt

HTML JS implementation
HTTP binding address
Catalog service via JSONRPC
Wire
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Summary

• OASIS SCA is a great way to build distributed
  services applications
• Compose services
• Develop service components
• Apply policies and bindings
• Agile and Flexible systems

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Useful links

• Articles about SCA
• http//www.infoq.com/articles/setting-out-for-sca
• http//www.osoa.org/display/Main/SCAResources
• Open Source implementation of SCA
• http//cwiki.apache.org/TUSCANY/
• SCA Specifications in OASIS
• http//www.oasis-opencsa.org/
• Email address
• mike_edwards_at_uk.ibm.com