Service Oriented Architectureand

Web services

Mohammed Luqman Shareef

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COM, DCOM Microsoft specific

EJB, RMI Java Specific

CORBA Platform and Language Independent

2010-02-08

Popular Distributed Application Frameworks/Technologies

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A software system is divided into highly flexible and re-usable components called services.

SOA is just an architecture blue print It is NOT a technical standard It is NOT a technology

2010-02-08

What is SOA?• SOA is an architectural

style of building software applications that promotes loose coupling between components for their reuse.

Coarse

grainedPlatform independent

Loosely coupledStandard Interface

4

Self-contained module that perform a predetermined task

Software component that have published contracts/interfaces

Black-box to the consumers

Platform-Independent

Interoperable

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What is Service ?

Systems today are bigger than ever before

Complexity increases exponentially with size

Systems need to be interconnected

OO solved the problems of small-medium sized systems

CO (Component Orientation) solved problems of medium-large systems

Neither OO nor CO could cope with the problems of very large systems, systems of systems, or integration between systems

Why SOA?

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Why SOA?

Order Manageme

nt

Provisioning

Inventory

Credit Manageme

nt

End Customer Portal Operator Portal Partner Portal

InvoicingNetwork Manageme

nt

Customer

Profiles

SalesManageme

ntBilling

Customer Info

Management

ServiceCatalog

Lets take a telecom enterprise system

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Why SOA?

Order Manageme

ntProvisionin

g

Inventory

Credit Manageme

nt

End Customer Portal Operator Portal Partner Portal

Invoicing

Network Manageme

ntCustome

r Profiles

SalesManageme

nt

Billing

Customer Info

Management

ServiceCatalog

Services

Towards Service-Oriented Architecture

Function oriented Build to last Prolonged

development cycles Application silos Tightly coupled Object oriented Known

implementation

Coordination oriented

Build to change Incrementally built

and deployed Enterprise solutions Loosely coupled Message oriented Abstraction

Managing services Service governance Performance Reliability security SLAs Interoperability of services

Challenges

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Loose couplingMinimize dependencies.

Service contractServices adhere to a communications agreement.

Service abstraction Hide the service execution logic from the outside world.

Service reusabilityLogic is divided into services for reuse.

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SOA: Architectural Principles

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Service composabilityServices can be assembled to form composite service.

Service autonomyServices have control over the logic they encapsulate.

Service discoverabilityServices can be found and assessed via available discovery mechanisms.

Service relevanceService presented at a granularity recognized by user a meaningful service.

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SOA: Architectural Principles

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SOA can be implemented using any service based technology such as CORBA, but the SOAP based web services standard implementation has gained wide industry acceptance, because these standards provide greater interoperability.

Key differences between CORBA and web service are

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SOA Implementation

CORBA Web serviceData model Object Oriented SOAP message exchangeClient Server coupling Tightly coupled Loosely coupledTransfer Syntax CDR (binary) XML (UTF)Type System IDL XML SchemasState Stateful StatelessService Discovery CORBA Naming service UDDI

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Realizing SOA with

Web Services

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Web service is a standard way of integrating Web-based applications using the XML, SOAP, WSDL and UDDI open standards over an Internet protocol backbone.

XML is used to tag the data, SOAP is used to transfer the data, WSDL is used for describing the services available and UDDI is used for listing what services are available.

Web services are loosely coupled computing services that can reduce the complexity of building business applications, save costs, and enable new business models. Services running on an arbitrary machine can be accessed in a platform- and language-independent fashion.

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What is web service ?

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Lookup for the tomato sellersYellow Pages: contain companies that are

selling tomatoes, their location, and contact information.

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How to buy tomatoes ?

Find the service offered according to my needs

Where, when and how can I buy tomatoes?

Buy the tomatoesDo the transaction

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Lookup for the Service ProviderRegistry: contain providers that are selling services, their location, and

contact information.

Find the service offered according to my needsWhere, when and how can I get the service?

Access the servicedo the transaction

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How to access a service?

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XML (eXtensible Markup Language)A uniform data representation and exchange mechanism

SOAP (Simple Object Access Protocol)Lightweight (XML-based) protocol for exchange of information in a decentralized, distributed environment

WSDL (Web Service Description Language)XML format that describes the web service

UDDI (Universal Description Discovery and Integration)Like yellow pages of Web services

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Components of a web service

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3 roles of service

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Service Vs. Consumer

Service

describes

End Point Exposes

Messages Sends/Receives

Contracts

Binds to

Service Consumer implements

Policy governed by

Sends/Receives

Adheres to

Understands

Serves

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1. Define the service implementation and compile it.

\WS>javac -d . HelloImpl.java

2. Use wsgen to generate the artifacts required to deploy the service.

\WS>wsgen -wsdl server.HelloImpl

3. Package the files into a WAR file and deploy it .

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Steps to develop a web serviceusing JAX-WS

package server;

import javax.jws.WebService;

@WebServicepublic class HelloImpl {

/** * @param name * @return Say hello to the person. */ public String sayHello(String name) { return "Hello, " + name + "!"; }}

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HelloImplService.wsdl

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HelloImplService.wsdl contd…

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HelloImplService_schema1.xsd

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4. Implement Client Code

5. Use wsimport to generate and compile the web service artifacts needed to connect to the service.

\WS>wsimport HelloImplService.wsdlparsing WSDL...

generating code...

compiling code...

6. Run the client.

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Steps to develop a web service contd…

package myClient;

import helloservice.endpoint.HelloService;import helloservice.endpoint.Hello;

public class HelloClient {

public static void main(String[] args) { try { HelloService service = new HelloService(); Hello port = service.getHelloPort();

String response = port.sayHello(“Luqman"); System.out.println(response); } catch (Exception e) { e.printStackTrace(); } }}

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WSDL is a contract between service provider and the consumer

A WSDL document describes◦ What the service can do◦ Where it resides◦ How to invoke it

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WSDL

Types

Message

Operation

Port Type

Binding

Port

Service

WSDL

WSDL elements

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TypesData type definition used in exchanging messages

MessageDescribes the logical content of data being communicated

OperationAn Abstract description of an action supported by the service

Port TypeA set of operations and messages involved with the service

BindingA concrete protocol and data format specification for a port type

PortA single end point defined as a combination of a binding and a network address

ServiceIdentifies which ports to group together

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WSDL elements

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SOAP is a lightweight (XML-based) protocol for exchange of information in a decentralized, distributed environment.

SOAP is a format for sending messages SOAP is independent of transport

protocol

A SOAP message is an ordinary XML document containing the following elements:◦ Envelope - identifies the XML document

as a SOAP message◦ Header - contains application specific info

like authentication etc.◦ Body - contains the message in request

and response◦ Fault - contains errors and status

information

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SOAPSOAP EnvelopeSOAP Header

Header Block

Message Body

SOAP Body

Fault Handlers

SOAP message structure

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<?xml version="1.0"?><soap:Envelopexmlns:soap="http://www.w3.org/2001/12/soap-envelope"soap:encodingStyle="http://www.w3.org/2001/12/soap-encoding">

<soap:Body xmlns:m="http://www.example.org/Hello">  <m:sayHello>    <m:name>Luqman</m:name>  </m:sayHello></soap:Body>

</soap:Envelope>

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SOAP Example

<?xml version="1.0"?><soap:Envelopexmlns:soap="http://www.w3.org/2001/12/soap-envelope"soap:encodingStyle="http://www.w3.org/2001/12/soap-encoding">

<soap:Body xmlns:m="http://www.example.org/stock">  <m:sayHelloResponse>    <m:return>Hello Luqman</m:return>  </m:sayHelloResponse></soap:Body>

</soap:Envelope>

Request

Response

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SOAP errors are handled using a specialised envelope known as a Fault Envelope

A SOAP Fault is a special element which must appear as an immediate child of the body element

<faultcode> and <faultstring> are required.

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SOAP Fault

Printing SOAP MessageWite a new Class MySOAPHandlerImplement handleMessage

public class MySOAPHandler implements SOAPHandler<SOAPMessageContext>{ public boolean handleMessage(SOAPMessageContext context) { try { SOAPMessage message = context.getMessage(); if ((Boolean)context.get(MessageContext.MESSAGE_OUTBOUND_PROPERTY) == true){ System.out.println("Request Message: "); }else{ System.out.println("Response Message: "); } message.writeTo(System.out); } catch (Exception ex) { ex.printStackTrace(); } return true; }

public Set<QName> getHeaders() { return null; }

public boolean handleFault(SOAPMessageContext context) { return true; }

public void close(MessageContext context) { }}

Printing SOAP Message contd...Wite a new Class MyHandlerResolverImplement

getHandleChain

public class MyMessageHandlerResolver implements HandlerResolver { public List<Handler> getHandlerChain(PortInfo portInfo) { List<Handler> handlerChain = new ArrayList<Handler>(); MySOAPHandler hh = new MySOAPHandler(); handlerChain.add(hh); return handlerChain; }}

Set the Handler Resolver in Client

Invoke the web methodRun the client

service.setHandlerResolver(new MyMessageHandlerResolver());

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UDDI is a set of specifications that is used to publish information for describing and discovering web services, finding businesses, building registries.

UDDI is a directory for storing information about web services.

UDDI communicates via SOAP.

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UDDI

To query companies with their names and attributes

To query businesses with their categories

Contains technical info on how to interact with the services

3 levels of information in UDDI

White Pages

Yellow Pages

Green Pages

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UDDI Structure

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Registry APIs (SOAP Messages)

• Inquiry API• Find things

• find_business• find_service• find_binding• find_tModel

• Get Details about things• get_businessDetail• get_serviceDetail• get_bindingDetail• get_tModelDetail

• Publishers API• Save things

• save_business• save_service• save_binding• save_tModel

• Delete things• delete_business• delete_service• delete_binding• delete_tModel

• security…• get_authToken• discard_authToken

Write the implementation and interface Generate WSDL file>java org.apache.axis.wsdl.Java2WSDL -o AdderWSDL.wsdl -l

http://localhost:8080/axis/services/Adder luqman.AdderInterface Generate server side and client side classes>java org.apache.axis.wsdl.WSDL2Java -o . -p luqman.generated -s AdderWSDL.wsdl Bind web service with functionality provider Bundle required classesjar cfv adderServerSide.jar luqman\*.class luqman\generated\*.classCopy the jar in the server’s axis/WEB-INF/lib folder>jar cfv adderClientSide.jar luqman\generated\AdderInterface.class luqman\generated\

AdderInterfaceService.class luqman\generated\AdderInterfaceServiceLocator.class luqman\generated\AdderSoapBindingStub.class

Register web services with Axisjava org.apache.axis.client.AdminClient luqman\generated\deploy.wsdd Write Web service client

Developing a web service using Axis

Printing SOAP Message in AXIS

String requestMessage = _call.getMessageContext().getRequestMessage().getSOAPEnvelope().toString();

String responseMessage = _call.getMessageContext().getResponseMessage().getSOAPEnvelope().toString();

System.out.println(“Request SOAP Message” + requestMessage);System.out.println(“Request SOAP Message” + responseMessage);

Edit the generated code in AdderSoapBindingStub.class - In the corresponding method of the Stub class add the following lines of code after the _call.invoke(...) statement

Adding attachments to SOAP Message in AXIS

CalculatorService service = new CalculatorServiceLocator();Calculator calc = service.getcalculator();

Stub stub = (Stub) calc;FileDataSource fs = new FileDataSource(new File("E:/Code/testA.txt") );DataHandler dh = new DataHandler(fs);stub.addAttachment(dh);

Client Side Code

MessageContext message = _call.getMessageContext(); //.getRequestMessage(); Iterator it = message.getRequestMessage().getAttachments();while (it.hasNext()) { AttachmentPart part = (AttachmentPart) it.next(); try { System.out.println("File Name : " + part.getDataHandler().getDataSource().getName()); InputStream is = part.getDataHandler().getInputStream(); while (is.available() > 0) { System.out.print((char) is.read()); } } catch (Exception ex) { ex.printStackTrace(); }

Display the Attachment in StubEdit the generated code in AdderSoapBindingStub.class - In the corresponding method of the Stub class add the following lines of code after the _call.invoke(...) statement

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REST

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Each unique URL is a representation of some objectEx : http://www.mycompany.com/india/hyd/employees

http://www. mycompany.com/india/hyd/employees/1234

HTTP GET Method operates on the resource.

Object state is transferred and stored at client.

Representation of the resource state in XML, JSON etc.

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RESTful web servicesREpresentational State Transfer

Every object has its own unique methods Methods can be remotely invoked over

the Internet A single URI represents the end-point,

and that's the only contact with the Web Data hidden behind method calls and

parameters Data is unavailable to Web applications

RPC vs REST

Every useful data object has an address Resources themselves are the targets for

method calls The list of methods is fixed for all

resources

RPC

REST

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RESTful web services contd…

Client side> Easy to experiment in browser> Broad programming language support> Choice of data formats> bookmarkable

Server side> Uniform Interface> Cacheable> Scalable> Easy failover

Benefits

> Resource identification through URI> Uniform interface

GET/PUT/POST/DELETE> Self-descriptive messages> Stateful interactions through hyperlinks

Principles

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ExampleRequestGET /india/hyd/employees/1234 HTTP/1.1Host: mycompany.comAccept: application/xml

ResponseHTTP/1.1 200 OKDate: Tue, 09 Feb 2010 11:41:20 GMTServer: Apache/1.3.6Content-Type: application/xml; charset=UTF-8

<?xml version="1.0"?><Employees xmlns="…"> <Employee name=“ABC”> … </Employee></Employees>

Method Resource

Representation

Statetransfer

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Developing a RESTful web service using JAX-WS

package com.sun.jersey.samples.helloworld.resources;

import javax.ws.rs.GET;import javax.ws.rs.Produces;import javax.ws.rs.Path;

@Path("/employees/{empid}")public class Employee{ @GET @Produces("text/xml") public String getEmployee(@PathParam(“empid") String empId) { ... … }}

Annotation

Description

@Path The @Path annotation's value is a relative URI path indicating where the Java class will be hosted, for example, /helloworld. You can also embed variables in the URIs to make a URI path template. For example, you could ask for the name of a user, and pass it to the application as a variable in the URI, like this, /helloworld/{username}.

@GET The @GET annotation is a request method designator and corresponds to the similarly named HTTP method. The Java method annotated with this request method designator will process HTTP GET requests. The behavior of a resource is determined by the HTTP method to which the resource is responding.

@POST The @POST annotation is a request method designator and corresponds to the similarly named HTTP method. The Java method annotated with this request method designator will process HTTP POST requests. The behavior of a resource is determined by the HTTP method to which the resource is responding.

@PUT The @PUT annotation is a request method designator and corresponds to the similarly named HTTP method. The Java method annotated with this request method designator will process HTTP PUT requests. The behavior of a resource is determined by the HTTP method to which the resource is responding.

@DELETE

The @DELETE annotation is a request method designator and corresponds to the similarly named HTTP method. The Java method annotated with this request method designator will process HTTPDELETE requests. The behavior of a resource is determined by the HTTP method to which the resource is responding.

REST Annotations

Annotation Description

@HEAD The @HEAD annotation is a request method designator and corresponds to the similarly named HTTP method. The Java method annotated with this request method designator will process HTTP HEAD requests. The behavior of a resource is determined by the HTTP method to which the resource is responding.

@PathParam The @PathParam annotation is a type of parameter that you can extract for use in your resource class. URI path parameters are extracted from the request URI, and the parameter names correspond to the URI path template variable names specified in the @Path class-level annotation.

@QueryParam The @QueryParam annotation is a type of parameter that you can extract for use in your resource class. Query parameters are extracted from the request URI query parameters.

@Consumes The @Consumes annotation is used to specify the MIME media types of representations a resource can consume that were sent by the client.

@Produces The @Produces annotation is used to specify the MIME media types of representations a resource can produce and send back to the client, for example, "text/plain".

REST Annotations

Authentication ( Identity check ) Authorization ( Access Control ) Confidentiality ( Encryption ) Integrity ( Signature Support ) Non-repudiation ( Ability to prove that a particular transaction is performed) Accessibility ( Ensuring that the service is not impacted by

attacks)

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Securing web servicesSSL is not enough

SSL provides point to point security

SSL provides security at transport level

SSL doesn’t support non-repudiation

WS needs end to end security

WS needs security at message level

Non-repudiation is critical for business WS

Web service security requirements

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XML digital signature ( IETF and W3C) XML Encryption ( W3C) SAML (Secure Assertion Markup Language) ( OASIS) WS-Security (Web Services Security) (OASIS)

◦ WS-SecureConversation◦ WS-Federation◦ WS-Policy◦ WS-Trust◦ WS-Privacy

XACML (Extensible Access Control Markup Language) (OASIS)

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Web service security standards

“BPEL is an XML language for defining the composition of web services into new services”

BPEL would require that every process ◦ Either has a “center” of execution◦ A process is composed of a large set of orchestration

definitions interacting with each other

BPEL assumes that business processes can be fully captured in a single definition, including all possible exception paths◦ Not sure this is the right assumption

BPEL

Identify the partners in the process

Declare the Partners in the Process

Design the workflow of the process

Define up the workflow process

Declare the Process Using BPEL Activity Constructs

Add Business Logic Using BPELConstructs

BPEL Steps

Open source specification project from the Object Management Group (OMG), describing a UML profile and metamodel for the modeling and design of services within a service-oriented architecture.

SoaML (SOA Modeling Language)

Dealer Network Architecture

The dealer network is defined as a community “collaboration” involving three primary roles for participants in this community: the dealer, manufacturer, and shipper. The following diagram illustrates these roles and services in the dealer network architecture.

SOAML Example

The enterprise service bus (ESB) is a software infrastructure that facilitates application integration.

An ESB does not itself implement SOA but provides the features with which SOA can be implemented.

Examples◦ Glassfish ESB (Sun)◦ Websphere ESB (IBM)◦ Biztalk Server (Microsoft)◦ JBOSS ESB

ESB

Invocation

Routing

Mediation

Message Processing

Service Orchestration

Complex Event Processing

Management

Common ESB Characteristics

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◦ SOAP - http://www.w3c.org/TR/soap

◦ WSDL - http://www.w3c.org/TR/wsdl

◦ UDDI - http://www.uddi.xml.org

◦ SAML - http://saml.xml.org

◦ ebXML - http://www.ebxml.org

◦ CORBA Vs. Web services - http://www2002.og/CDROM/alternate/395

◦ SoaML - http://www.omg.org/spec/SoaML

◦ BPEL - www.oasis-open.org/committees/wsbpel

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For more information

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Questions?

56

Thank You

2010-02-08