G O B E Y O N D C O N V E N T I O N WORF: Developing DB2 UDB based Web Services on a Websphere...

G O B E Y O N D C O N V E N T I O N

WORF: Developing DB2 UDB based Web Services on a Websphere Application Server

Kris Van Thillo,ABIS Training & Consulting

©2003 BMC SoftwareApril 18, 20232

Agenda

J2EE and Web Services• Introduction

›About Web Services

›About Stored Procedures• Architecting Web Services

›Understand application requirements

›The server component model - the client invocation model

›WSDL, SOAP and UDDI constructs• DB2 Stored Procedures and Web Services

›WORF

›DB2 XML Extender

›Web Services


IntroductionWeb Services and Stored Procedures


Web Services - Definition

Web Services are

“Software applications identified by a URI, whose interfaces and bindings are are capable of being defined, described and discovered by XML artifacts, supporting direct interactions with other software applications using XML based messages via internet-based protocols.”

...


Web Services - Standards

andbased on open standards

• XML - eXtensible Markup Language• SOAP - Simple Object Access Protocol• WSDL - Web Services Description Language• UDDI - Universal Description, Discovery and Integration


Webservices - Execution


Web Services - Execution

Step 1: Define and build Web Service (method signature)• function/operation(s), parameters• return value, errors/exceptions

Step 2: Deploy Web Service• to SOAP router• deployment descriptor

Step 3: Create client application• Java calls SOAP API

Step 4: Execute the client application


Web Services - Why?

Advantages:• loosely coupled and coarse-grained service granularity• programming language independent, interoperable• transport independent• mutiple invocation styles: static or dynamic• multiple communication styles: synchronous or asynchronous• open, extensible, standards based: based on XML• composable


About Stored Procedures ...

Stored Procedures


Advantages of Stored Procedures

• Faster execution

• Reduced network traffic

• Modular programming

• Increased security


Writing Stored Procedures

• Languages: Java, C,…

• Generation with GUI:

›Stored Procedure Builder (v7)

›Development Center (v8)

• SQL/PL

DB2 UDB v8 supports the dynamic CALL statement


Architecting Web Services


Common Web Service Architectures

Request /Response

SOAP request sent to receiverReceiver processesSOAP response sent back to sender

Non component basedapplicationsSimple Java

RPC SOAP request send to haveoperation executed on remote objOperation executed on the objectResult returned as a SOAP response

Component basedapplications, eg.Stateless session beans

Fire and Forget Sender sends SOAP request toreceiver(s)Sender does not block

Messaging


Server component model Client invocation model

• Server component model

›Request-Response and RPC paradigms: use solutions with basic synchronous blocking behavioure.g. Java classes, EJBs, stored procedures

›Fire and Forget: JMS architecture and MDBeans for asynchronous behaviour

• Client invocation model

›Static Proxy, static proxy generated, based on WSDL

›Dynamic Proxy

›Dynamic Invocation Interface


WSDL, SOAP, UDDI Constructs

SOAP provides a myriad of constructs!Consider:• usage styles

› SOAP ‘RPC’ style

› SOAP Document style• encoding styles

› encoded

› literal


Stored Procedures and Web Services


WORF - Basic Architecture

WORF: a piece of software plugged in the Websphere application server used by all DB2 Web Service enterprise applications.


The DB2 XML Extender

Offers …

› Stored Procedures

› Triggers

› User Defined Functions (UDF)

› User Defined Datatypes (UDT)

› Supporting tables

… to extend DB2 functionality!


Two methods (i)

XColumnColumn data = XML documents

DB2 used as XML document repository

Validation of XML docsStoring XML docs

Search through XML docs


Two methods (ii)

XCollectionDB2 used as database (no XML in

DB2)XML is transport language

Validation of XML docsDecompose XML docs into data

Compose XML docs from data


DADs

XML document› Validate

› DTD-id

› Method

› Detailed description of data mapping: DB2 vs. XML


DB2 Web Services

WORF: software plugged in the WebSphere application server used by all DB2 Web Service enterprise applications.


Web Service Object Runtime Framework (WORF)

Provides for:

›Resource-based deployment and invocation, i.e.

DADX based

optionally other resources that help define the web

service

›Automatic service redeployment

›Automatic WSDL and XSD generation

›Automatic documentation

›Automatic test page generation


WORF configuration files

description of deployed service

servlet mapping

service specificconfig

database specs

engine


DADX Document Access Definition eXtension

›XML document

›a DADX

for each Web Service

›Web Service meths:

DADX operations

›Web Service

documentation

›Query Description

<DADX xmlns="http://schemas…">

<operation name="listPersons">

<query>

<SQL_query>SELECT pfname, plname FROM

db2.persons</SQL_query>

</query>

</operation>

<operation name="InsertPerson">

<call>

<SQL_call>call db2.InPers(:lname, :com) </SQL_call>

<parameter name="lname" type="xsd:string"/>

<parameter name="com" type="xsd:string” kind="out"/>

</call>

</operation>

</DADX>


Possible DADX operations / DB2 manipulations

› select

› insert

› update

› delete

› call

› retrieveXML

› storeXML

SQL based queries XML based queries


SOAP request processing by WORF

Processing sequence:

› loads the DADX

› optionally loads a DAD file

› replaces query parameters

› connects to DB2

› runs the SQL statement

› commits the database transaction

› formats the result into XML

› returns the response in a SOAP envelope


DB2 Web Services

WORF: software plugged in the WebSphere application server used by all DB2 Web Service enterprise applications.


Why will Web Services Succeed?

Because:

› Implementation de-coupled from interface any language

open standard transport ‘distributed’ technology

› Optimized for Internet standard based

› ‘No’ assumptions about technology at either side of the chain

› Backed by key software vendors: IBM, Oracle, MS, etc.

G O B E Y O N D C O N V E N T I O N WORF: Developing DB2 UDB based Web Services on a Websphere...

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