apache axis: open source web services...

All Contents © 2003 Burton Group. All rights reserved.

Apache Axis: Open Source Web Services Platform

Chris HaddadSenior Consultant

chaddad@burtongroup.comwww.burtongroup.com

February 26, 2004

2Apache Axis: Web Services Platform

We are

here

3

Thesis• Demanding business environment

• Support the virtual enterprise• Access actionable information in real-time• Integrate with 2nd and 3rd tier partners

• Web Service Platform opportunity• Automatic generation of communication bridge• Heterogeneous interoperability

• Platform of choice = Axis• Flexible, extendible, component model• Advanced tooling

Apache Axis: Web Services Platform

4

Agenda• Web Services Review• Web Services Platform • Axis Architecture• Axis Advanced• Building Axis clients and services• Get Rolling!

Apache Axis: Web Services Platform

5Web Services Review: Technical Definition

A Web Service:• An application that exposes its functionality through a

“Web API”• Built using the Web Services Framework

Web Services Framework:• A new type of middleware technology • For application-to-application communication• Based on XML, SOAP, WSDL, UDDI

6Web Services Review: Business Definition

Integration technology• Heterogeneous interoperability• For internal and external applications• Relies on pervasive Internet technology

Supports a Service-Oriented Architecture• Reusability • Consistency• Flexibility• Centralized control• Multi-user/multi-constituency support

7

ServiceProvider

ServiceContract

Service

ServiceConsumer

Client

ServiceBroker

RegisterFind

Bind

Web Services Review: Service-Oriented ComputingWeb Services Review: Service-Oriented Computing

8Web Services Review: Service-Oriented Computing

9

Web Services Framework: XML, SOAP, WSDL, UDDI

Web Services Review: Core Technologies

UDDIRegistry

WSDL

WebService

SOAPClient

Points to description

Points to serviceDescribesServiceFinds

Service

Communicates withXML Messages

10Web Services Platform

Web services management extensions

Web services platform (tools)• Development• Deployment • Management

What is a Web Services Platform?• Tools

• Generate WSDL and proxies• Administer services• Monitor traffic

• Run-time• SOAP Message processing• Service agent invocation

• Management Extensions• Monitoring• Service Provisioning• Security

Web services platform (runtime)

11Web Services Platform: Runtime

Client

Corporate applicationDesktop application

Wireless deviceWeb portal

etc.

Java Application Server

WSDL

SOAPProxy

Web Services Runtime Server

Web services runtime server

Code generated by WS tools

SOAPMessageProcessor

WebService

The application that implements

the service

WS Container

SOAP and WSDL

processing

Application code

DB

Legacy

DeploymentDescriptor(WSDD)

12Axis Architecture: Web Services Runtime

13

Service Dispatcher

Axis Architecture: Web Services Platforms

Message ProcessingPipeline Service Agent

(Web Service)

Transport

SOAP Message Processor

Web Services Runtime Server

Web Service Container

Serialization Framework

AdministrationServices

ConfigurationRepository

Tools

Axis Components overview

SecurityFramework

14Axis Architecture

Axis Components – Detail View

Administration

Service Dispatch

MSG

Message processing

Handlers

SecurityManagement

Transform

SerializationFramework

DeserializerSerializer

Java Object Configuration Repository

Type Mapping

Flows

FaultResponse

Request

ServiceConfiguration

Transport

HTTP

Web Service

SMTP

BEEP

JMS

ToolsAdminClient

Java2WSDL

WSDL2Java

SOAPMonitor

COMEJBRPC

Security

15Axis Architecture

Extension Points

16Axis Architecture

Transport Responsibilities• Interface to network protocol• Accept SOAP requests• Create Message Context• Send SOAP Response

SOAP Request

SOAP Response

MessageContext

TransportListener(http)

17

Axis Engine

SOAP Request

SOAP Response

MessageContext

TransportListener(http)

Axis Architecture

Message Processing Responsibilities• Identification of SOAP node’s role and initialize blocks• Map SOAP message to Java objects • Invoke interceptors (chains and handlers)• Process SOAP header directives• Hand-off to service dispatcher

Chain (request)

Handler Handler

Chain (response)

Handler

18Axis Architecture

SOAP Response

SOAP Request

Request flow

Response flow

Fault Flow

Pivot Handler(provider)

TransportListener(http)

Message Flows• Assignment of processing blocks for SOAP request

separated from SOAP response• Exception processing channel defined by Fault Flow

Axis Architecture

19Axis Architecture

SOAP Request

SOAP Response

Request flow

Response flow

Fault Flow

Transport Chains

Global Configuration

Chains

LocalService Chains

TransportListener(http) Pivot Handler

(provider)

Processing Scope• Localize execution of handlers and chains• Header fault check (MU) Identification of SOAP node

Axis Architecture

20

Axis Engine

Chain (request)

Handler Handler

Axis ArchitectureSerialization Framework Capabilities• Mapping Java types to/from XML determined by

• literal schema or section 5 encoding style. Document and rpc conventions.• JAX-RPC compliant

• Typical mappings• primitive data types (int, char, float, etc.) • Generic arrays and Java beans• custom serialization

Chain (response)

Handler

MessageContext

SOAP Request

SOAP Response

TransportListener(http)

SerializationFramework

Best Practice Tips:•Use doc/literal•Avoid collections•Use MSG-style to bypass body serialization

21

Axis Engine

ServiceEndpoint

ServiceProvider

(rpc)

SerializationFramework

Axis Architecture

Service Dispatching Responsibilities• Load web service agent• Format endpoint call• Execute business logic• Serialize return value as SOAP message

MessageContext

SOAP Request

SOAP Response

TransportListener(http)

Chain (request)

Handler Handler

Chain (response)

Handler

22Axis ArchitectureAxis Registry Deployment Descriptor (WSDD) Key Elements

• Service Descriptor• SOAP URI• Dispatcher type• Service Java class• WSDL File• Type mappings and handlers

• Handler Descriptor• Logical name• Handler Java class• Configuration parameters

• Type Mapping• XML QName• Java serialization class• Factories

<deployment><handler>

<parameters></handler><service>

<typemapping/></service>

</deployment>

23Axis Advanced

Advanced Tools• Development

• WSDL2Java• Java2WSDL

• Deployment• AdminClient

• Management• Tcpmon• SOAPMonitor

24

Advanced Interoperability through Java Web Service Standards

JAX-RPC: RMI-style API• Application interacts via native Java objects• Standard Java to/from XML mappings• Proxy automatically generates SOAP messages• WSDL-aware

SAAJ: Low-level API• Application works with SOAP envelope• Attachments

JWSDL: WSDL API• Used by SOAP runtime and tools (WSDL compiler and generators)• Used with DII

J2EE Integration• JMS• EJB

Axis Advanced

25Axis Advanced

Client API Choices• Compiled Stub

• Compile time binding• Service interface and proxy specifics defined at compile time

• Dynamic Proxy• Runtime binding• Service interface and protocol specifics defined at compile time

• Dynamic Invocation Interface (DII)• Runtime discovery• Service interface and protocol specifics determined at runtime

26Building Axis clients and services

Practical design• Building a Web Service

• Infrastructure handlers• Security• Session Management• Transformation

• Mapping Types• WSDL Generation

• Building a Client• Proxy code generation from WSDL or DII• Supporting complex types

27

Building a Web Service• Build a new service

• Start with code• Follow procedure for an existing application

• Start or follow-up with WSDL• WSDL compiler generates application skeleton• Fill in appropriate application code

• Best Practices• How to encapsulate an application

• Expose it directly• Build a façade, adapter, or wrapper

• Decision criteria:• Does it have an existing API?• What’s the interface granularity?

• Methods• Data Objects

Interoperability Tips

Don’t expose Java-centric objects to SOAP clients

(i.e. turn maps into arrays)

Polymorphism and inheritance can be

dangerous

Building Axis clients and services

28Building Axis clients and services

Web Service Components

29Building Axis clients and services

Building a Web Service Client• Find WSDL file• Generate client interface• Write the client code

• Use the interface to invoke operations on the remote service

30

Compiling a Client Proxy

Building Axis clients and services

Order ServiceSubmit OrderGet Order StatusList BackordersGet Customer HistoryGet Order History

Operation: Submit OrderInput message: OrderOutput message: ConfirmationUse: SOAP over HTTPLocation: http://my.org/orders

WSDL

GenerateCode

GenerateWSDL

ClientSubmitOrder

SOAPClientProxy

SOAP message<Order>

SOAP message<Confirmation>

31Axis: Open source web services platform

Features Recap• Component architecture

• Flexible configuration options• Multiple extension points (transport, message processing, encoding)

• Advanced tools and utilities• WSDL and proxy code generation• Service administration• Server-side and Client-side Infrastructure

• Interoperability• Automatic serialization of complex types• Major Web Service and Java standards supported

32

J2SE platforms• Apache Axis *• Apache SOAP *• U Indiana XSOAP *

J2EE platforms• Borland Enterprise Server ^• IBM WebSphere ^• JBoss .NET ^• Macromedia JRun ^• Oracle 9i ^• Pramati ^

^ Based on Apache Axis/SOAP* Open Source

Web Services Vendors• Infravio ^• Grand Central ^• FlamencoNetworks ^• Collaxa ^• SoapKnox ^

Axis momentum……• Version 1.1 ready to support the enterprise• Axis used by major J2EE and Web Service vendors

Axis: Open source web services platform

33

Interested in more information?• Axis Specific

• Home http://ws.apache.org/axis• Wiki http://nagoya.apache.org/wiki/apachewiki.cgi?AxisProjectPages• Mailing lists http://ws.apache.org/axis/mail.html

• Interoperability• White Mesa http://www.whitemesa.net• Microsoft SOAP interop http://www.mssoapinterop.org

• Web Services Framework• SOAP1.1 http://www.w3.org/TR/SOAP/• WSDL 1.1 http://www.w3.org/TR/wsdl• XML Schema http://www.w3.org/TR/xmlschema-0/

• Java Web Services• JAX-RPC http://java.sun.com/xml/jaxrpc/• SAAJ http://java.sun.com/xml/saaj/• JWSDL http://www.jcp.org/en/jsr/detail?id=110

Axis: Open source web services platform