XML and Web Services Delphi 2005 Win32

1. XML and Web ServicesDelphi 2005 Win32

2. Disclaimer • <?xml version=“1.0”?> • Occasionally omitted for clarity • Too short a session • to cover XSLT, XPath or XMLSchema in any depth • to explore a non-trivial web service • Too short a session to cover discovery, specification and classification of web services • No UDDI (Universal Description, Discovery and Integration ) • No WSDL (Web Service Description Language) • Not a SOAP session! • SOAP is an “XML protocol”, we’ll use it over HTTP Delphi 2005 Refactoring

3. Agenda • Motivation • Prerequisites • Working with XML documents • XML using Delphi 2005 • .net • VCL using System.XML • Win32 • Web Services in Delphi 2005 • ASP.net • Win32 • Summary Delphi 2005 Refactoring

4. Prerequisites • XML Syntax • XML’s raison d’être • platform-independence; interoperability • human readable & self-describing, on the whole • extensibility • parser availability <?xml version=“1.0”?> <!-- this is a comment --> <employees> <employee no=“1”> <name>Frank Butcher</name> <car reg=“R872 BFS” model=“Vectra” /> </employee> </employees> Delphi 2005 Refactoring

5. Motivation • To look at XML and web service support in Delphi 2005 • “Rightly or wrongly, XML is everywhere” • We need platform-independent data exchange mechanisms • Strong-typing is crucial • for validation • for verification • New to XML? • Demonstration of common [XML] idioms • Loading XML documents • Creating XML documents • Traversing XML documents • Locating XML elements • Validating XML documents • Transformation Delphi 2005 Refactoring

6. Motivation • Loosely coupled architectures • disconnected vs connected models • language neutral data access • Five years ago: XML was emerging as a universal data format • Over the last two/three years: XML is a universal data format • XML is a core part of the .net Framework Delphi 2005 Refactoring

7. Working with XML documents • Two distinct methods: • Document Object Model (DOM) • Simple API for XML (SAX) Delphi 2005 Refactoring

8. Working with XML documentsDocument Object Model • entire XML document is loaded into memory • not very memory efficient • rapid access • random access to any part of the document • implemented in MSXML 2 onwards • OpenXML • The CLR Delphi 2005 Refactoring

9. W3C Document Object Model (DOM) • DOM is a standard set of “interfaces” • the DOM is a specification • there is no implied code • consistent object hierarchy • Vendors build “DOM implementations” • “code that implements the interfaces” • e.g. MSXML3, MSXML4 • e.g. Xerces • e.g. OpenXML Delphi 2005 Refactoring

10. Working with XML documentsSimple API for XML (SAX) • event-driven • access to a document is incremental • forward-only access • access speed limited by media latency, etc. • very memory efficient • ideal for processing large XML documents • implemented in MSXML3 onwards Delphi 2005 Refactoring

11. No SAX in .net • SAX • Forward-only, read-only access to an XML document • Ability to skip elements that are not required • Implemented in .net’s XMLReader class: • XMLTextReader • no validation against DTD or schema • XMLNodeReader • no validation, returns instances of XmlNode • XMLValidatingReader • full validation against DTD or multiple schemas Delphi 2005 Refactoring

12. demo Using XML in Delphi 2005 Delphi 2005 Refactoring

13. Web Services in Delphi 2005 • Prior to Delphi 6, web services were: • Built using raw TCP/IP and SOAP; requests/responses built manually; possibly used Indy • Not type-safe • Error-prone • Delphi 6 changed all that, web services are now: • Still built using SOAP, but managed by tool support • Type-safe, both on the client and server • Because of tool support, repeatable, very much less error prone Delphi 2005 Refactoring

14. demo Web Services in Delphi 2005 Delphi 2005 Refactoring

15. Design Considerations • Use .net classes with care • System.Xml is available for: • Windows 98, Windows NT 4.0, Windows Millennium Edition, Windows 2000, Windows XP Home Edition, Windows XP Professional, Windows .NET Server family, .NET Compact Framework - Windows CE .NET Delphi 2005 Refactoring

16. Summary • The [XML] DOM is portable between platforms • learn it once, use it often • often extended for persistency (load/save) • Building Web Services • Target multiple platforms: Win32, .net and even mobile devices • Consider resilience, don’t put all your eggs in one basket • Try to purchase the web service (and source!) to deploy on your infrastructure • Watch out for changing interfaces! Delphi 2005 Refactoring

17. Resources (web-sites) • O’Reilly’s resources: • XML.COM: http://www.xml.com/ • WebServices.xml.com: http://webservices.xml.com/ • What is Service-Oriented Architecture (SOA)? • http://webservices.xml.com/pub/a/ws/2003/09/30/soa.html • Web Service Repositories/Brokerages: • http://www.salcentral.com • http://www.xmethods.com • Taking a step back from the power and abstractions: • http://www.craigmurphy.com/SOAP/SimpleSOAPClient.htm Delphi 2005 Refactoring

18. Resources (Books) Web Services Essentials Etham Cerami Addison-Wesley, 2002 ISBN 0-596-00224-6 (avoid books “WSDL heavy”) _____________________________ XML in a Nutshell (3rd Edition) Elliotte Rusty Harold, W.Scott Means Addison-Wesley, 2004 ISBN 0-596-00764-7 Delphi 2005 Refactoring

19. Contact and Update Information Craig Murphy Updated slides, notes and source code: http://www.CraigMurphy.com Delphi 2005 Refactoring

20. Questions? Delphi 2005 Refactoring

21. Delphi 2005 Refactoring