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Lesson 5

Lesson 5. Database Interactivity and WDDX Simeon Simeonov and Dick Steflik. Agenda. The need for Web distributed data exchange The crisis of web applications The need for XML middleware Web Distributed Data Exchange (WDDX) WDDX scenarios Demos Call to action.

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Lesson 5

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  1. Lesson 5 Database Interactivity and WDDX Simeon Simeonov and Dick Steflik

  2. Agenda • The need for Web distributed data exchange • The crisis of web applications • The need for XML middleware • Web Distributed Data Exchange (WDDX) • WDDX scenarios • Demos • Call to action

  3. Metcalf’s Law of Connectivity • Metcalf’s Law of Connectivity • The value of a network is a function of the number of nodes connected to that network; value grows exponentially with each node • The Web is the new computing platform • The number of nodes on the Net is huge, and growing at an ever increasing rate, so...

  4. Have we Achieved World Peace? • One big assumption does not hold true • Network nodes leverage peers’ data and services • A Web system must be a data and service portal, not just an outward facing end-user application • Web applications are not so designed • Most view web applications as having a fixed end-user base working through web browsers • The combination of HTML + script provides no separation of data and processing

  5. Case: FedEx Package Tracking • Individuals track packages via browsers, but... • FedEx’s real customers are corporations • They want to integrate their order tracking systems with FedEx’s package tracking system • They cannot do this using the existing system • Redesign requires “public data interfaces” • Requires exchange of structured data between browsers and servers and in between servers

  6. The Crisis of Web Applications • Structured data exchange is not happening • HTTP is a flat text-based protocol • Browsers are data-starved; despite ever increasing processing capabilities, they do little more than user-interface related work • Servers are separated by the walls imposed by under-powered data exchange • Solution • Break these walls down; let web applications execute on the entire network • We know XML can help! But, how?

  7. Native XML Approach • DTD design • XML data generation • XML parsing and processing • SAX, DOM, … • XML transformation • CSS, DSSSL, XSL, …

  8. Sounds Great, But… • Native XML processing is still not very easy • XML is a young field • The standards landscape is in flux • Many tools are immature and/or expensive • Mass developer community lacks expertise • How can the Web take advantage of the benefits of XML in this environment?

  9. The Need For XML Middleware • Solution • A mechanism for exchanging structured data that hides the details of XML processing • What is required? • The Web is simple, pragmatic, and ubiquitous • Page-based web applications that run on web application servers (Perl scripts, Active Server Pages, ColdFusion) rule the field

  10. How should it be done? • Work directly with application data • Developers never see XML, but they benefit from it • Cross platform • Different OSs: Windows, Mac, Unix • Different languages: ColdFusion Markup Language (CFML), VBScript, JavaScript, Java, C/C++, COM, CORBA, Frontier, Perl, PHP, Python • Open and flexible • Easy to contribute to • Can track evolving W3C standards • Free!

  11. Application Data Serialization The Net Deserialization Application Data How should it work? Platform X Platform Y

  12. Web Distributed Data Exchange • WDDX DTD • Language and platform neutral representation of common application data structures: strings, numbers, booleans, date-time values, arrays, associative arrays, and recordsets • WDDX platform modules • Serialization/deserialization modules for CFML, COM (C/C++, ASP, and all Windows apps), JavaScript (browser), Perl, and Java • WDDX datatypes • Common API uses native datatypes when possible

  13. Technology Comparisons • XML DTDs • WDDX abstracts the process of DTD creation, XML generation, and XML parsing for app data • DOM • WDDX is an API built on top of DOM • SOAP and WebBroker • WDDX is about data, not object method requests • WIDL • WDDX has no notion of a service or an interface • RDF and DCD • WDDX is not about meta-data

  14. WDDX Evolution • WDDX DTD is versionable • Multiple versions of WDDX can interoperate • WDDX can track evolving W3C standards • Source code is open • Encourages involvement and participation • Lowers the cost of WDDX-enabling a platform • Allaire is working together with third parties • It’s free! • The more nodes speak WDDX, the better

  15. When Should One Use WDDX? • Point-to-point data exchange • No pre-existing XML/SGML content • Application-level data is ‘produced’ • Applications ‘consume’ the data • Only one use for the XML data representation • Multiple ad hoc data exchanges • Little or no benefit from custom vocabularies • Example: per page browser-server data exchange

  16. The Net XML WDDX WDDX Scenarios WDDX ColdFusion Server XML CF Server Windows/Java Client ASP Server JavaScript Browser

  17. Web Technology Adoption Path • XMLless Web • Structure, where art thou? • XML middleware • Browsers and servers exchange structured data • Developers can benefit from WDDX now • Proof of XML benefits to the enterprise • XML-enabled Web • A better place for all

  18. Call to Action • Want to see WDDX in action? • Download ColdFusion: www.macromedia.com • Visit the WDDX site: www.openwddx.org • Want to try WDDX out? • download Software Development Kit (SDK) from www.openwddx.com • Send email to beta@allaire.com. It’s free!

  19. the WDDX SDK • What is in the SDK • COM / ActiveX Implementation • Java Implementation • JavaScript Implementation • Perl Implementation • PHP Implementation • ColdFusion Implementation • "A2Z" Example Database

  20. COM/ActiveX Implementation • set of DLLs (that must be registered) that implement the required XML parser and WDDX components • Server-side ActiveX • Plugs into IIS for ASP use

  21. Java Implementation • The Java implementation is distributed as a .jar archive of compiled .class files, and as source .java files. You will use these files with whatever Java development tool (or JDK) that you are using

  22. JavaScript Implementation • The JavaScript implementation is distributed as three JavaScript (.js) files. The "core" file is wddx.js, which defines the WddxRecordset and WddxSerializer objects. • Additionally, the archive includes wddxDes.js, which defines the WddxDeserializer object, and wddxRsEx.js, which provides additional functionality for recordset objects.

  23. Perl Implementation • A brand-new WDDX.pm module for Perl has been graciously contributed to the SDK by Scott Guelich. The module provides the same kind of support as the other implementations, including serialization, deserialization, and the new binary support

  24. PHP Implementation • The support is not distributed as part of the SDK at this time. • to find out more you can find out more about the PHP/WDDX functionality, including reference documentation, at http://www.php.net/manual/ref.wddx.php3

  25. Cold Fusion Implementation • The Cold Fusion implementation is included in Cold Fusion 4.0 and later versions • Currently, JavaScript support for WDDX does not provide a way to deserialize a WDDX packet. The server will deserialize it into Javascript and deliver it to the requesting browser

  26. WDDX to Javascript • to deserialize a WDDX packet to Javascript at the browser some additional scripts are required: • wddxDes.js - Nate Weiss • xparse.js - Jeramie Miller • search the web for the file names, they are in a number of places

  27. Basic concepts Take a native object; serialize it into a WDDX packet Send it across the network Deserialize it back into a native object Serializing the native objects into WDDX packets gives us al way of of moving environment specific (Java, CF,Perl…) objects around the network and delivering them to the same environment or another other environment

  28. example select FirstName,LastName,Email from Employees produces a ColdFusion record set, serialixing the recordset produces a WDDX packet <wddxPacket version='0.9'> <header></header> <data> <recordset rowCount='5' fieldNames='FIRSTNAME,LASTNAME,EMAIL'> <field name='FIRSTNAME'> <string>Carolynn</string> <string>Dave</string> <string>Linda</string> <string>Aaron</string> <string>Peter</string> </field> <field name='LASTNAME'> <string>Peterson</string> <string>Heartsdale</string> <string>Stewart</string> <string>Smith</string> <string>Barken</string> </field> <field name='EMAIL'> <string>CPETERSON</string> <string>FHEARTSDALE</string> <string>LSTEWART</string> <string>ASMITH</string> <string>PBARKEN</string> </field> </recordset>

  29. deserialized into Javascript EmployeeData=new WddxRecordset();_t2=newArray();_t2[0]="Carolynn";_t2[1]="Dave";_t2[2]="Linda"; _t2[3]="Aaron";_t2[4]="Peter";EmployeeData.firstname=_t2;_t2=newArray();_t2[0]="Peterson"; _t2[1]="Heartsdale";_t2[2]="Stewart";_t2[3]="Smith";_t2[4]="Barken";EmployeeData.lastname=_t2; _t2=newArray();_t2[0]="CPETERSON";_t2[1]="FHEARTSDALE";_t2[2]="LSTEWART";_t2[3]="ASMITH"; _t2[4]="PBARKEN";EmployeeData.email=_t2;_t0=null;_t1=null;_t2=null; Note that because of the serialization and deserialization that the object that started out as a ColdFusion recordset has ended up as a set of Javascript arrays

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