stream 8 - soa in focus © 2007 ibm corporation © 2008 ibm corporation service data objects (sdo):...

STREAM 8 - SOA IN FOCUS

© 2007 IBM Corporation

© 2008 IBM Corporation

Service Data Objects (SDO): Handling Data Consistently in a SOA Environment

Kelvin Goodson, IBM UK – [email protected] EngineerOpen Source SOA, Apache Tuscany

SDO Session

© 2008 IBM Corporation2

SDO 2.1 Spec Introduction

SDO Session

© 2008 IBM Corporation3 Page

What are Service Data Objects?

Service Data Objects (SDO) provide:

– Uniform access to data from heterogeneous sources

• XML, RDB, EJB, LDAP, SOAP etc...

– Has both static (strongly typed) and dynamic programming models

– Disconnected “data graph” capable of tracking changes

– Meta-data for easy introspection of data types

– Relationship integrity enforcement

– Language neutral APIs with implementations in Java, C++ and PHP

SDO Session


SDO for COBOL

SDO Session


Instance and Model

SDO Session


How do I store and retrieve SDOs ?

XML Documents

– SDO specification describes serialisation to and de-serialisation from XML documents.

SDO specification discusses a Data Access Service (DAS)

– DAS is a mediator between data sources and SDO applications

– Apache Tuscany currently implements an RDB DAS, and some work done on an LDAP DAS

SDO Session


Combining SDO and DAS

SDO Client

ChangeSummary

Data GraphDataObject

: EJB: InvoiceEJB: Customer

JDBC

XPath / XQuery

Local

XML/HTTP

CCI / Proprietary

Data Access Service

RDB

XML DB

Web service

JCA

SDO Session


Combining SDO with SCA

SCA is the component model Components may be wired together SDO DataObjects are data passed between and manipulated by Components DAS is a SCA component with a special implementation type (implementation:das)

Component

AccountServiceComponent

Component

AccountDataServiceComponent

Service

AccountService

Reference

StockQuoteService

Composite AccountComposite

WebServer

.NetWeb

Service

SCA

SCASCA

SDO

SDO

SDO

RDB

SDO Session


SDO Components and Key Features

Generated data API: POJO beans

Dynamic data API: DataObject

Change summary API: ChangeSummary

Introspection API: Type and Property

Sequence API where instanceorder is preserved

Relationship Integrity

XML and XSD Integration– XPath Navigation through Graphs of Data

XML-based serialization for transferring data sets on the wire– Can conform to pre-defined XML Schema

– Can generate XML Schema

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SDO Session


The Strongly Typed SDOs also Implement the Dynamic API

SDO Session


Static (Generated) Data API

POJO interfaces/classes

Strong-typed accessors

public interface Person {

String getName();

void setName(String name);

Address getAddress();

void setAddress(Address address);

}

Person p = (Person) dataFactory.create(Person.class);

p.setName("John");

Address a = (Address) dataFactory.create(Address.class);

p.setAddress(a);

<complexType name="Person"> <attribute name="name" type="string"/> <element name=“address" type=“Address"/></complexType><complexType name=“Address”> …

SDO Session


Dynamic Data API (commonj.sdo.DataObject)

The Dynamic SDO API provides a reflective way to introspect and manipulate data– Recall: Static SDO can be cast to DataObject

Customer c = CustomerFactory.createCustomer();

((DataObject)c).setString("name", "John"); // Set name

<complexType name="Person"> <attribute name="name" type="string"/> <element name=“address" type=“Address"/></complexType><complexType name=“Address”> …

SDO Session


Example 1 – Accessing DataObjects

// use SDO API to find the employee, at index 1 in the list. List departments = company.getList("departments");

DataObject department = (DataObject) departments.get(0); List employees = department.getList("employees");

DataObject employeeFromList = (DataObject) employees.get(1);

DataObject employee = company.getDataObject

("departments[1]/employees[2]");

// Get an employee using an SDO xpath expression DataObject employee = company.getDataObject (“departments[number=123]/employees[SN=0002]”);

SDO Session


// create a new employee DataObject newEmployee = department.createDataObject("employees"); newEmployee.set("name", "Al Smith"); newEmployee.set("SN", "0004"); newEmployee.setBoolean("manager", true);

// Set employeeOfTheMonth company.set("employeeOfTheMonth", newEmployee);

Example 2 – Updating DataObjects

company.setString(“companyName", "ACME");

<company name="ACME" employeeOfTheMonth="0004"> <departments name="Advanced Technologies" location="NY" number="123"> <employees name="John Jones" SN="0001"/> <employees name="Jane Doe" SN="0003"/> <employees name="Al Smith" SN="0004" manager="true"/> </departments> </company>

SDO Session


SDO Meta-Model

SDO provides a simple, universal meta-model

– Used across JavaBeans, XML, or any data source

– Useful for tools and IDE’s (Model in MVC)

Meta-data Classes

– Type

• Has name, URI, instance class, and properties

– Property

• Has name, type, default value, etc.

DataObject obj = …;Type type = obj.getType();Collection c = type.getProperties();Iterator i = c.iterator();while (i.hasNext()) {

Property prop = (Property) i.next();System.out.println(prop.getName());

}

SDO Java XSD

Type Class Type

Property Field Element

Attribute

SDO Session


Type System Scopes

HelperContext

– Agent of scoping for Types

– provides access to

• TypeHelper• DataFactory• XSDHelper• XMLHelper• EqualityHelper• CopyHelper• DataHelper

– HelperProvider.getDefaultContext()

– Application can create new HelperContexts

SDO Session


XML/XSD integration

Key interfaces: XMLHelper and XSDHelper

Direct correspondence between XML and DataObjects

– commonj.sdo.XMLHelper

• Load and save DataObjects to XML streams

XSD mapping to and from SDO

– commonj.sdo.XSDHelper

• Get XML Schema specific information:

– isElement, isMixed, local name, appinfo

– Define Types and Properties from XSDs

• Annotations or XSLT for mapping control

– Generate XSDs from Types and Properties

SDO Session


Create SDO types from an XML schema

XSD model can be directly used to define SDO types

XSDHelper xsdHelper = …;

TypeHelper typeHelper = …;

// Populate the SDO types from the XSD

URL url = XMLSample.class.getResource(“/stockquote.xsd”);

InputStream inputStream = url.openStream();

xsdHelper.define(inputStream, url.toString());

inputStream.close();

// Look up the SDO Type

Type type = typeHelper.getType(“http://stock”, “Quote”);

// Get the XSD namespace URI for a SDO type

String ns = xsdHelper.getNamespaceURI(type);

SDO Session


Registering Type-System for SDO Runtime

Register types dynamically from XSD

Register types statically (strongly typed)

Instance is still of type Employee

→ Data Object instantiation:DataObject employee = dataFactory.create(NAMESPACE, “Employee”);

→ Data Object instantiation:Employee empl = (Employee)dataFactory.create(Employee.class);OrDataObject empl = dataFactory.create(NAMESPACE, “Employee”);

SDO Session


CreateCompany Example

SDO Session


SDO API for Programatic Type Creation

Uses DataObject API

Build data graph describig Typs system – then compile

Type TypeHelper.define(DataObject)

List<Type> TypeHelper.define(List<DataObject>)– Permits circular references in metadata (Properties of Type as yet not “defined”)

DataObject cType = scope.getDataFactory().create("commonj.sdo", "Type"); cType.set("uri", "http://example.com/customer"); cType.set("name", "Customer");

Type intType = typeHelper().getType("commonj.sdo", "Int"); DataObject cNumProperty = customerType.createDataObject("property"); cNumProperty.set("name", "custNum"); cNumProperty.set("type", intType); …… Type registeredType = typeHelper.define(cType);

SDO Session


Load/Save XML documents

XMLHelper can load SDO from XML or save SDO to XMLDataObject quote = …;

XMLHelper xmlHelper = …;

ByteArrayOutputStream baos = new ByteArrayOutputStream();

// Save the data object as an XML document

xmlHelper.save(quote, "http://www.example.com/simple", "stockQuote", baos);

byte[] xml = baos.toByteArray();

// Load the XML bytes as an XMLDocument

XMLDocument document = xmlHelper.load(new ByteArrayInputStream(xml));

// Get the root DataObject

quote = document.getRootObject();

SDO Session


XML

<purchaseOrder orderDate="1999-10-20">

<shipTo country="US">

<name>Alice Smith</name>

<street>123 Maple Street</street>

<city>Mill Valley</city>

<state>PA</state>

<zip>90952</zip>

</shipTo>

...

</purchaseOrder>

country= USname= Alice Smithstreet= 123 Maple Streetcity= Mill Valleystate= PAzip= 90952

XML / SDO Mapping

Values

Properties

orderDate=1999-10-20

shipTo

SDOPurchaseOrder Type

USAddress Type

SDO Session


Use SDO to invoke a Web Service

Load the SOAP Envelope model from the XSD

// Create the helperContext

HelperContext helperContext = SDOUtil.createHelperContext();

// Load the soap envelope XSD

XSDHelper xsdHelper = helperContext.getXSDHelper();

URL xsd = SoapEnvelope.class.getClassLoader().getResource("soap-envelope.xsd");

InputStream xsdStream = xsd.openStream();

xsdHelper.define(xsdStream, null);

xsdStream.close();

// Load the WSDL model

URL wsdl = SoapEnvelope.class.getClassLoader().getResource("stockquote.wsdl");

InputStream wsdlStream = wsdl.openStream();

xsdHelper.define(wsdlStream, null);

wsdlStream.close();

SDO Session


Open Types

SDO “Open” Types

– Type.isOpen()

– Presence of <xsd:any/> implies Type.isOpen() = true

– TypeHelper.defineOpenContentProperty(String, DataObject);

– TypeHelper.getOpenContentProperty(“namespace”, “name”);

– XSDHelper.getGlobalProperty(“namespace”, “name”)

Property p = typeHelper.getOpenContentProperty( “myExtraInfoUri”, “usefulData”);DataObject usefulExtraInfo = dataFactory.create(p.getType);…openDataObject.getList(p).add(usefulExtraInfo);assert usefulExtraInfo.getInstanceProperties().size() == usefulExtraInfo.getType().getProperties().size() +1;

SDO Session


Create and populate the SOAP message

Construct the SOAP Envelope as a DataObject

DataFactory dataFactory = helperContext.getDataFactory();

DataObject envelope = dataFactory.create("http://www.w3.org/2003/05/soap-envelope", "Envelope");

DataObject header = envelope.createDataObject("Header");

DataObject body = envelope.createDataObject("Body");

Property prop = xsdHelper.getGlobalProperty("http://example.com/stockquote.xsd", "getLastTradePrice", true); // is element

DataObject request = dataFactory.create(prop.getType());

request.setString("tickerSymbol", "IBM");

body.getList(prop).add(request);

SDO Session


Producing the XML for the SOAP message

StringWriter writer = new StringWriter();

XMLHelper xmlHelper = helperContext.getXMLHelper();

XMLDocument doc = xmlHelper.createDocument(envelope, "http://www.w3.org/2003/05/soap-envelope", "Envelope");

xmlHelper.save(doc, writer, null);

// We can write to an HTTP output stream to invoke the Web Service

<?xml version="1.0" encoding="ASCII"?><tns:Envelope xmlns="http://ns1" xmlns:tns="http://www.w3.org/2003/05/soap-envelope" xmlns:xsd1="http://example.com/stockquote.xsd"> <tns:Header> <myHeader>001</myHeader> </tns:Header> <tns:Body> <xsd1:getLastTradePrice> <tickerSymbol>IBM</tickerSymbol> </xsd1:getLastTradePrice> </tns:Body></tns:Envelope>

SDO Session


Relationship Integrity

Containment

– By default Properties represent containment relationships

DataObject root = …DataObject originalChild = root.getDataObject(“child1”);DataObject parent = originalChild.getContainer();

assert parent == root;

DataObject newChild = dataFactory.create(ChildType.class);root.set(“child1”, newChild);

assert originalChild.getContainer() == null;assert newChild.getContainer() == root

SDO Session


Other Relationships

Non-containment

– Properties can be made to represent Non-containment relationships

• xsd:ID and xsd:IDREF in Schema translate to non-containment

– Without non-containment all data graphs would be single rooted hierarchies

Opposite

– Bidirectional relationships (other than parent-child)

– Requires non-containment (Property type = xsd:ID, xsd:IDREFS or anyURI)

– sdo:oppositePropertyType required

SDO Session


Sequenced Types

Type.isSequenced() for instance ordered DataObjects

Triggered by

– xsd:mixed=“true”

– repeating choice

– sdo:sequenced=“true”

– …

DataObjet.getSequence()

– Iterate over Lists of Property Value pairs

– Sequence.getProperty(int), Sequence.getValue(int)

SDO Session


Sequenced Example

SDO Session


Tracking changes for disconnected data

Service data is often disconnected from the source in SOA Service data can be changed in the flow of business processes

// Create an empty data graph and add a root object, an instance of type Quote

DataGraph dataGraph = SDOUtil.createDataGraph();

DataObject quote = dataGraph.createRootObject("http://www.example.com/simple", "Quote");

// Begin logging changes: usually DAS responsibility

ChangeSummary changeSummary = dataGraph.getChangeSummary();

changeSummary.beginLogging();

// Modify the data graph: client code

quote.setString("symbol", "fbnt");

…

quote.setDouble("change1", 1000);

changeSummary.endLogging(); // DAS code

ByteArrayOutputStream baos = new ByteArrayOutputStream();

// Serialize with change summary data

SDOUtil.saveDataGraph(dataGraph, baos, null);

SDO Session


Data Access Services - DAS

Data Access Services (DAS) provides the data access solution with two fundamental capabilities:

– Results of a data source query execution returned as a graph of Data Objects

– Graph modifications reflected back to data source as a series of Creates/Updates/Deletes

SDO Client

ChangeSummary

Data GraphDataObject

: EJB: InvoiceEJB:

JDBC

XPath / XQuery

XML/HTTP

CCI / Proprietary

Data Access Service

RDB

XML DB

Web service

JCA

SDO Session


DAS High Level Architecture

SCA component with DAS impl. type

SDO Session


Apply changes back to the data store

Change-aware DAS can retrieve the data and update the data by applying the deltaDAS das = DAS.FACTORY.createDAS(getConnection());

// Read customer

Command select = das.createCommand("Select * from CUSTOMER");

// ChangeSummary is enabled by DAS

DataObject root = select.executeQuery();

DataObject customer = (DataObject) root.get("CUSTOMER[1]");

// Modify customer

customer.set("LASTNAME", "Pavick");

// Build apply changes command

das.applyChanges(root);

SDO Session


DAS example

SDO Session


SDO Implementations

Open Source implementations of in context of SDO– The Tuscany project (incubating at Apache) for SCA, SDO and DAS– The Eclipse SOA Tools Platform Project– The SOA for PHP project

Commercial SDO Implementations– XIC from Xcalia– HydraSDO from Rogue Wave Software– FireStorm/SDO from CodeFutures Software– AquaLogic Data Services Platform 2.0 from BEA– Virtual XML Garden from IBM– IBM WebSphere Process Server V6.0.x– IBM WebSphere Application Server V6.1– IBM WebSphere Application Server V6.1 Feature Pack for SOA (beta)– SAP NetWeaver Application Server, Java(TM) EE 5 Edition

SDO Session


WID has a “Bo-Editor” to define XSD/SDO

SDO Session


WAS v6 EJB – RSA Tooling

SDO Session


WAS v6 JDBC DAS – RSA Tooling

SDO Session


Summary Unified data access to heterogeneous data sources

– Unified programming model for business data– DAS layers to take care of different data sources and format conversions on the edges

Unified support for both static and dynamic data APIs– Generated POJO interfaces/classes for strongly-typed APIs– Dynamic APIs: DataObject/Type/Property– Static SDOs can be mixed with Dynamic SDOs

Support for disconnected programming models– ChangeSummary to track changes– Change-aware DAS update– DAS specification mentioned in the SDO 3 objectives document

Multiple language support– Java– C++– PHP– …

SDO Session


Ready to try?

Finalised specs -- OSOA collaboration

– http://www.osoa.org

Articles etc.

– http://www.osoa.org/display/Main/SDO+Resources

– http://java.sys-con.com/read/313547.htm

– http://java.sys-con.com/read/358059.htm

– http://incubator.apache.org/tuscany/das-overview.html

Open Source

– Apache Tuscany Project

• http://incubator.apache.org/tuscany– PHP & PECL

• http://www.php.net/• http://pecl.php.net/package/SCA_SDO

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