XFORMS in minutes Chris Bailey. Presentation overview Introduction –What & Why How XFORM works...
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XFORMS in minutes Chris Bailey
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Transcript of XFORMS in minutes Chris Bailey. Presentation overview Introduction –What & Why How XFORM works...
XFORMS in minutes
Chris Bailey
Presentation overview• Introduction
– What & Why
• How XFORM works– Code examples– Specific features
• Problems & Issues
• References
<FORM> is dead – all hail the <XFORM>!
• XForms offers a higher level approach to writing traditional XHTML form-based input.
• Became a W3C recommendation in 2003
• Second edition of the spec released in Sept 2006
• XForms WG currently working on 1.1
Why use Xforms?• Clearer design
– Implements separation of concerns via a MVC approach– data model independent from presentation– ‘logic’ easier to code
• Less code– No javascript! <script/>
• Works with existing technologies…– Designed with AJAX in mind
Underpinning technologies
• XML• XML Schema• XPath
• DHTML• HTTP• Javascript• Ajax…
What you (as the developer) need to know
What the xform handling code uses
How to do I produce XFORMS?• XFORMS are all written in XML
• When executedXFORMS (D)HTML+Javascript
– Pre-compile source code
– Dynamic compilation on server
– Dynamic compilation on client (browser)
XFORM implementations• Pre-compilation
– AJAXForms– XFormation
• Server support– Orbeon– IBM Workplace Forms
• Browser support– X-Smiles
• Browser addons/extensions– Mozilla XForms– MozzIE– FormsPlayer– FormFaces
Quotes• “XForms is the most-implemented W3C
specification ever at this stage in its life-cycle.” [W3C XForms FAQ]
• British Government's e-government interoperability framework current guidance is to use the XForms standards as defined by W3C
XFORMS MVC Approach
<patient>
<title/>
<sex/>
<dob/>
<children/>
</patient>
Model: Define the format of the data
Controller: Specify constraints and relationships
View: Simply reference parts of the model
XFORMS MVC Approach
<patient>
<title/>
<sex/>
<dob/>
<children/>
</patient>
No empty nodes allowed
String, max length 50 chars
Enumeration (Male|Female)
Date value
Integer range{0 < x < 10}
Model: Define the format of the data
Controller: Specify constraints and relationships
View: Simply reference parts of the model
XFORMS MVC Approach
<patient>
<title/>
<sex/>
<dob/>
<children/>
</patient>
No empty nodes allowed
String, max length 50 chars
Enumeration (Male|Female)
Date value
Integer range{0 < x < 10}
Model: Define the format of the data
Controller: Specify constraints and relationships
View: Simply reference parts of the model
Show me some XFORMs!<html>
<head>
<xforms:model>
<xforms:instance>
<person>
<name/>
</person>
</xforms:instance>
<xforms:bind nodeset="/person/name" type="xs:string"
constraint=“string-length(.) < 50"/>
</xforms:model>
</head>
<body>
<p>Hello world. Please enter your name here:
<xforms:input ref="/person/name“/></p>
<body>
</html>
Data model
Control binding
View
Show me some XFORMs!<html>
<head>
<xforms:model>
<xforms:instance>
<person>
<name/>
</person>
</xforms:instance>
<xforms:bind nodeset="/person/name" type="xs:string"
constraint=“string-length(.) < 50"/>
</xforms:model>
</head>
<body>
<p>Hello world. Please enter your name here:
<xforms:input ref="/person/name“/></p>
<body>
</html>
Data model
Control binding
View
Referencing data with XPATH• View and controllers reference data model with
XPATH expressions
e.g.
<xforms:bind nodeset="…" required="true" />/credit-card/number
/credit-card/*[position() = 1]
/credit-card/*[starts-with(local-name(),’expiration’)]
/credit-card/*
Binding attributes (validation)
• type<xforms:bind nodeset="/credit-card/expiration-month" type="xs:integer" />
• constraint<xforms:bind nodeset="/credit-card/expiration-month"
constraint=". >= 1 and 12 >= ."/>
• required<xforms:bind nodeset="/credit-card/expiration-month" required="true" />
Binding attributes (cont)
• calculate<xforms:bind nodeset="/person/age" calculate="year-from-date (current-date()) - year-from-date(../dob)" />
• readonly<xforms:bind nodeset="/person/age"
readonly="if (../dob == ‘’) then ‘false’ else ‘true’" />
• relevant<xforms:bind nodeset="/person/password" relevant="false" />
View attributes<xforms:select1 ref="/moving-details/my-delivery-company" appearance="…">
<xforms:itemset nodeset="/companies/delivery"><xforms:label ref="label"/><xforms:value ref="@value"/>
</xforms:itemset></xforms:select1>
appearance="full" appearance="compact" appearance="minimal"
Disadvantages of XFORMS• Enhanced accessibility
– The abstraction that xforms offers means that you need not worry so much about the presentation issues
• Reduced accessibility – At the mercy of the xforms handler– Can AJAX ever be made accessible?
Did I mention it’s all XML?
• OH MY GOSH IT’S ALL XML!!!!!!
• Not for the faint hearted (or people without a CS degree!)
• Editors should make this easier when they arrive – OpenOffice.org 2.0 already here
References• XForms 1.0 (Second Edition) W3C
Recommendation 14 March 2006– http://www.w3.org/TR/xforms/
• XForms 1.1 W3C Working Draft – http://www.w3.org/TR/xforms11/
• Orbeon Forms– http://www.orbeon.com/
