XForms is an XML application that represents the next generation of forms for the Web. This document specifies the requirements for XForms 1.1.
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XForms 1.1 will build upon the solid foundation set forth by XForms 1.0 - the Next Generation of Web Forms. This version makes incremental improvements over version 1.0 to provide expanded behaviors for the existing and established XForms Model-View-Controller Framework and by embracing SOAP. This version also makes adjustments to XForms to facilitate its adoption in other host languages.
Requirement: Support SOAP as a new method of submission.
In XForms 1.0, the
submission element allows sending part of
any instance to the server, but there is no reciprocal functionality for
handling the returned data. In particular, there is no ability to pass
partial instance data back and forth between client and server based on
conditions expressed via XForms model properties and/or triggered by user
Requirement: Allow the
submission element to specify
that the returned data can go in any instance, not just the instance from
which the submitted data was drawn.
Requirement: Allow the
submission element to specify
that the returned data can be used to replace a node in the instance data. A
use case would be submitting an element containing a UK postal code and
having the returned data replace an instance subtree containing an
In XForms 1.0, a
repeat element creates the user interface
elements in its content once for each node in the collection indicated by its
nodeset attribute. If the
results in an empty collection, then no user interface elements are
To dynamically add user interface elements as more data becomes available,
insert is used to add another node to the collection to which
repeat nodeset is bound. However, the
element in XForms 1.0 requires that the collection contain a prototypical
node in the initial instance data that is to be duplicated in the
Due to this architecture, it is not possible to use
repeat collection that is initially empty. The use case for an
initially empty collection is a shopping cart application, where the user
expects to start with an empty shopping cart.
Secondly, it is also more difficult to express forms in which the data
content is derived not from the prototypical instance but from other instance
data obtained after initialization. Each leaf node in the subtree rooted by
the new node in the
repeat collection must currently be filled
with a separate invocation of
setvalue even if the desired
subtree structure exists elsewhere in instance data.
Requirement: Allow a method for copying a subtree of instance data (identified by a single apex element node) and pasting the subtree copy into an identified instance element node. The method must provide a facility for indicating where to put the subtree copy in the children of the target node (e.g. first, last, after a given child).
The XForms 1.0 Schema currently allows
bind elements to be
nested. One capability of nested binds is that an outer
provide the XPath nodeset against which an inner
to provide various model item properties.
In XForms 1.0, user interface elements can indicate an XPath node or
nodeset. Alternately, a
bind attribute can be used to indicate by IDREF a
bind element whose whose XPath nodeset is to be used with the
user interface element.
Other than the possible issue of referring to a bind in another model, a
bind element should be able to reference another
bind element to provide a starting XPath nodeset with the same
effect as if the former
bind had been nested within the
bind element to use a
bind attribute to obtain its starting XPath nodeset from another
A use case for this requirement is to allow forms processing systems to separate business rules (the 'inner' binds that specify computed model item properties) from database rules (the 'outer' binds that specify data locations within the instance). Forms management systems could then construct forms more easily since the business rules could simply be concatenated to the database rules if the former referred to the latter by ID reference rather than having to be nested within them.
Requirement: Let email address be a primitive (recognized) XForms datatype for schema data validation.
XForms expresses a processing model and user interface for the
modification of data expressed in XML. Currently, the XML can be obtained
from within the document or from a server. It would be useful to allow XForms
processors to edit XML obtained from the local computer, and to return the
edited XML to the local computer. To avoid security issues, this cannot be
done by simply using a
file scheme in the
attribute of the XForms
Requirement: Allow an XForms processor to provide an XML editing capability.
Applications that require mathematical exponentiation (raising X to the power Y) are not possible in XForms 1.0, such as the compounded interest calculation for a periodic loan payment.
Requirement: Allow the ability to calculate XY in XForms computational expressions.
The ability to reuse the XPath node-set referenced by a
has proven to be a valuable and powerful capability. For example, the XPath
node-set referenced by a
bind can be used by another
bind or by a user interface element. It is useful to extend this
referencing capability to XPath expressions.
Requirement: Allow the ability to obtain the XPath node-set
associated with an identified
bind from within an XPath
In some forms, it is necessary to perform a simple table lookup based on
user input. For example, suppose a form contains an element
conversionTable that provides conversion rates for various
currencies to the user's local currency. Based on the conversion selected by
the user, the appropriate exchange rate would be used in a calculation.
XPath provides the ability to perform this type of search using
predicates. To continue the above example, suppose each child of
conversionTable is a
rate element with the exchange
rate as content and a
currency attribute. Further, let a
separate instance element called
currency provide the storage
for the currency selected by the user, and let
the amount to convert. The converted amount could then be obtained using the
The problem with this approach is that it uses absolute referencing to obtain the currency value selected by the user. If the converted amount, amount, and currency elements were moved to a deeper point in the instance data, then the XPath would have to be rewritten.
Requirement: Allow an XPath expression to perform a table search using a key whose value is referenced relative to the initial context node of the XPath expression.
To increase widespread adoption of XForms in web applications, it is necessary to reduce the difficulty of authoring XForms in XHTML, which is currently hindered by the incessant need to flip between the host language namespace and the XForms namespace when authoring the user interface component of a form.
Requirement: Simplify Authoring XForms in XHTML2.
To facilitate the adoption of XForms in other XML tag sets, which is stated as a key goal in the XForms 1.0 requirements, implementation support for the XForms model will be a conformance level formally recognized by a distinct namespace from the XForms user interface related elements and attributes.
Requirement: Let the XForms 1.1 namespace be applied to the XForms 1.1 model, and let the XForms user interface related elements and attributes be defined abstractly so they can appear in a separate namespace or in the namespace of each host language.
This document was produced with the participation of current XForms Working Group participants: