Presentation 8: SOAP in a distributed object framework, Application Servers & AXIS SOAP.

Presentation 8:SOAP in a distributed object framework,

Application Servers & AXIS SOAP

Ingeniørhøjskolen i ÅrhusSlide 2 af 14

Outline

• SOAP and Web Services in relation to Distributed Objects

• The AXIS Project – Open Source Java SOAP Server– Introduction to the Apache Tomcat Application Server– Introduction to the AXIS Project– How to install

SOAP & Web Services in relation to Distributed Objects


SOAP and Distributed Objects

• SOAP in it self has nothing to do with objects• There probably is SOAP API’s for C and COBOL• The trick is the supporting API’s converting

objects to WSDL and SOAP for serialization across the network

• Using the Proxy Pattern for decoupling – perhaps with the Façade Pattern for larger granularity– Emmerich: Accessing distributed objects is expensive– Use larger granularity

• More on Architecture later in the course


Proxy Pattern (GoF version)

WatchClient

RealWatchProxyWatch TestWatch

setTime()

setTime() setTime() setTime()

Objects of RealWatch class are locateed on a different machinethan the Client object.This is an example of Remote Proxy – which is anArchitectural Pattern. from GoF

abstract

GoF: Gang Of Four (Design Pattern bog af Gamma m.fl.)


Proxy Pattern (B. Douglas version)

ClientObject

SOAPProxy

Serverobject

BD.s212

Client component

Server component

Proxy Pattern Client

Server Proxy

Proxy (= en stedfortræder)

By encapsulatingThe SOAP communicationin a Proxy,we have decoupled theClient Object fromneeding to knowthat it calls overThe Internet. Thus making it easyto implementdifferent Middlewareand use the Serverobject locallyWe could do the same for

The Server object


Façade Pattern (also GoF)

Used for encapsulation and decouplingUsed for encapsulation and decoupling

The entire Client Subsystem is decoupled from the serverand a Client Proxy hides the SOAP implementation (also Server Proxy)

This is known as Client Stubs & Server Skeletons

The entire Client Subsystem is decoupled from the serverand a Client Proxy hides the SOAP implementation (also Server Proxy)

This is known as Client Stubs & Server Skeletons

Frameworks for Webservices &The AXIS Project – Open Source

Java SOAP Server


How to make a Webservice with SOAP

• You need an application or API capable of supporting:– Communication over the Internet (HTTP)– Security (SSL)– XML Parsing capabilities– …

• Two examples of this:– Apache Tomcat Application Server with AXIS– Microsoft Internet Information Server

• We will use them both – though starting with the Apache Tomcat Application Server and the AXIS project – this will be introduced here


Apache Tomcat Application Server

• Apache Project is a open source project – widely supported by Sun & IBM (but not Microsoft)– Including a huge amount of free coding effort from both

• It consist of a long range of projects including:– Apache Web Server

• The most used web server in the world (and its free!)• The most secure, with SSL cap., and NT, Linux & UNIX support• Huge amount of ”plug-in” modules• One of theese being the Apache Tomcat AS

– Apache Tomcat Application Server• Capable of running JAVA applications• JSP/Servlets• And projects embedded into this –

– The AXIS Project• The former Apache SOAP Server• Runs embedded in Tomcat


Apache Tomcat AS• Works on:

– Windows, UNIX, LINUX, Mac– Can be compiled to any platform (with some work)

• Can be found at:– http://jakarta.apache.org/tomcat/index.html

• Server listening for events: – HTTP on port 8080 (optionel)– Executes Servlets/JSP and JAVA applications– AXIS is an embedded project within the Tomcat environment

SOAP ClientJava, C++, C#,

Delphi, VB Application

SOAP ClientJava, C++, C#,

Delphi, VB Application

SOAP over HTTPSOAP over HTTP

Web ServerApache /MS IIS

Web ServerApache /MS IIS

AS/SOAPServer

(Tomcat with

AXIS)

AS/SOAPServer

(Tomcat with

AXIS)

JSP/ServletJSP/

Servlet

WebService

WebService

ObjectObject

ObjectObject

Common code base!Common code base!

http://jakarta.apache.org/tomcat/index.html







AXIS Project

• Provides us with a suitable framework• Runs embedded in Apache Tomcat – just download

– http://xml.apache.org/axis/

• But can run on ANY Application Server– BEA, WebSphere,

• Supports full WSDL• Supports SOAP communication via:

– HTTP, SMTP, FTP and open for extension

• Build in security, log, error and fault handling (some are still “under construction”)

• Tools for WSDL Stub & Skeleton creation:– WSDL2Java &– Java2WSDL

• Flexible deployment system

http://xml.apache.org/axis/





The AXIS Project – How to Install


How to Install

• We do not need the Apache Web Server– As Tomcat has its own HTTP capabilities

• Start with Apache Tomcat Application Server– http://jakarta.apache.org/tomcat/index.html

• Test installation is OK• Then Install the AXIS Project

– http://xml.apache.org/axis/

• I have prepared a brief installation help document to be found at the course web site

Presentation 8: SOAP in a distributed object framework, Application Servers & AXIS SOAP.

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