1.1 The XForms Core Module
The XForms Core Module defines the major structural elements of XForms, intended for inclusion in a containing document. The elements and attributes included in this module are:
| Element | Attributes | Minimal Content Model |
|---|
| model | Common, functions (QNameList), schema (list of xsd:anyURI), version (xforms:versionList) , src (xsd:anyURI), resource (xsd:anyURI) | (instance|xs:schema| submission|bind|Action|import)* |
| instance | Common, src (xsd:anyURI), resource (xsd:anyURI) | (ANY) |
| submission |
Common
ref (binding-expression)
bind (xsd:IDREF)
resource (xsd:anyURI)
action (xsd:anyURI) [deprecated]
mode ("asynchronous"|"synchronous")
method ("post"|"get"|"put"|"delete"|"multipart-post"|"form-data-post"|"urlencoded-post"|Any other NCName|QNameButNotNCName)
validate (xsd:boolean)
relevant (xsd:boolean)
serialization ("application/xml"|"application/x-www-form-urlencoded"|"multipart/related"|"multipart/form-data"|"none")
version (xsd:NMTOKEN)
indent (xsd:boolean)
mediatype (xsd:string)
encoding (xsd:string)
omit-xml-declaration (xsd:boolean)
standalone (xsd:boolean)
cdata-section-elements (QNameList)
replace ("all"|"instance"|"text"|"none" | QNameButNotNCName)
instance (xsd:IDREF)
targetref (nodeset XPath Expression)
separator (';' | '&')
includenamespaceprefixes (xsd:NMTOKENS)
| (resource | method | header)*, Action* |
| bind | Common, Model Item Properties, nodeset (model-binding-expression) | (bind)* |
| import | src (xsd:anyURI), resource (xsd:anyURI) | EMPTY |
Elements defined in the XForms Actions module, when that module is included, are also allowed in the content model of model and submission, as shown above.
Within the containing document, these structural elements are typically not rendered.
The XForms Processor must ignore any foreign-namespaced attributes that are unrecognized.
Note that the presence of foreign namespaced elements is subject to the definition of the containing or compound document profile.
1.1.1 The model Element
This element represents a form definition and is used as a container for elements that define the XForms Model.
No restriction is placed on how many model elements may exist within a containing document.
Common Attributes: Common
Special Attributes:
- functions
Author-optional space-separated list of XPath extension functions (represented by QNames) required by this XForms Model. Guidance on the use of this attribute is at ???.
- schema
Author-optional list of xsd:anyURI links to XML Schema documents outside this model element. The XForms Processor must process all Schemas listed in this attribute.
Within each XForms Model, there is a limit of one Schema per namespace declaration, including inline and linked Schemas.
The schema definitions for a namespace are determined to be applicable to instance nodes based on an instance schema validation episode initialized to lax processing. When an element lacks a schema declaration, the XML Schema specification defines the recursive checking of children and attributes as optional. For this specification, this recursive checking is required. Schema processing for a node with matching schema declarations is governed by its content processing definition, which is strict by default.
Note:
The schema list may include URI fragments referring to elements located outside the current model elsewhere in the
containing document; e.g. "#myschema". xs:schema elements located inside the current model need not be listed.
- version
Author-optional attribute with a default value of empty string and legal values defined by the datatype xforms:versionList. Examples are "1.0" and "1.0 1.1". If one or more versions are indicated by this attribute on the default model, then an XForms Processor must support at least one of the listed language versions of XForms. Otherwise, the XForms Processor must terminate processing after dispatching the event xforms-version-exception to the default model. If the XForms Processor supports more than one language version indicated by the version setting on the default model or if the version setting on the default model is empty string (whether specified or by default), then the XForms Processor may execute the XForms content using any language conformance level available to it. If any non-default model has a version setting that is incompatible with the language version selected by the XForms Processor, then the XForms Processor must terminate processing after dispatching the event xforms-version-exception to the default model.
- src
Author-optional link to externally defined model definition. If the link traversal fails, it is treated as an exception (???).
- resource
Author-optional link to externally defined model definition. If the link is traversed and the traversal fails, it is treated as an exception (???).
If the src attribute is given, then it takes precedence over inline content and the resource attribute, and the model content is obtained from the link. If the src attribute is omitted, then the model content is obtained from inline content if it is given or the resource attribute otherwise. If both the resource attribute and inline content are provided, the inline content takes precedence.
Editorial note: Meaning of resource on model | |
Do we intend to save only running instance data when doing save/restore for remotely access models? Other model content,
such as bind, submission etc are static and so do not need save/restore function. A different policy for
processing resource on model and import seems to be required. |
If the model content is given by a link (from src or resource), then the model is formed by consuming the linked resource as follows. The root of the linked resource must be
an XForms model element. Model attributes are transferred to the referencing model element and
processed as though originally authored there. Note that src and resource attributes are allowed on external
model definitions provided they do not result in cyclical references.
The content model for externally referenced models is identical to that of local content. Foreign namespaced elements and attributes are not supported
by the core structure of XForms but may be defined by extension processors.
Child content of external model elements is imported into the referencing model and processed as though originally authored there.
If the link cannot be traversed, then processing halts after dispatching an xforms-link-exception with a resource-uri of the link that failed.
Examples:
This example shows a simple usage of model, with the XForms namespace defaulted:
<model id="Person" schema="MySchema.xsd">
<instance resource="http://example.com/cgi-bin/get-instance" />
...
</model>
Handler for xforms-version-exception
<model>
<message level="modal" ev:event="xforms-version-exception">
<output value="event('errorinformation')"/>
</message>
...
</model>
...
<model id="m2" version="1.1">
...
</model>
Since the version attribute is not specified on the model, the XForms Processor may choose any language conformance level, which may be incompatible with the version setting of the second model. Therefore, the message action occurs during initialization of the second model due to its version incompatibility with the default model.
An Example of Differing but Compatible Version Settings
<model version="1.0 1.1">
...
</model>
...
<model id="m2">
...
</model>
Since the version attribute is not specified on the second model, it is compatible with any choice made based on the version setting on the default model.
This example shows a usage of remote model content:
<model id="Person" src="http://www.example.com/person_model.xml"/>
where person_model.xml contains:
<model schema="MySchema.xsd">
<instance>
...
</instance>
</model>
This example shows a usage of remote model content accessed through the import element:
<model id="Person">
<import src="http://www.example.com/person_model.xml">
...other inline model content or import statements
</model>
where person_model.xml is as shown above.
| Editorial note: Treatment of IDs in imported model content | |
WG minutes discuss use of name vs id for bind elements but what should be the treatment
for instance as shown above? |
1.1.2 The bind Element
Element bind selects a node-set from the instance data with either
a model binding expression in the nodeset attribute or the
default of the in-scope evaluation context node. Other attributes on element bind encode
model item properties to be applied to each node in the
node-set. When bind has an attribute of type xsd:ID, the bind then associates
that identifier with the selected node-set.
Common Attributes: Common, Model Item Properties (author-optional)
Special Attributes:
- nodeset
An author-optional attribute containing a model binding expression that selects the set of nodes on which this bind operates.
If the attribute is omitted, the default is the in-scope evaluation context node.
See ??? for details on model item properties.
See ??? for details on how the evaluation context is determined for each attribute of the bind element.
1.1.3 The import Element
The import element allows model content to be reused from external resources and included in a parent referencing model along with
other imports and inline model content. Multiple imports may be used to build up models from a collection of reusable model definitions.
Note that imported model content forms a single coherent model from a behaviorial perspective with extenal model elements
behaving as though direct child elements of the referencing model. In other words, no submodel structure is created by the import
mechanism.
Implementations may choose to merge imported content into a single model infoset or maintain separate
infosets provided the behavior of the resulting overall model is as described above.
import references are resolved during the model-construct phase of initialization.
Special Attributes:
- src
Author-optional link to externally defined model definition. If the link traversal fails, it is treated as an exception (???).
- resource
Author-optional link to externally defined model definition. If the link is traversed and the traversal fails, it is treated as an exception (???).
If the src attribute is given, then it takes precedence over inline content and the resource attribute, and the model content is obtained from the link.
If the src attribute is omitted, then resource is required and the model content is obtained from inline content if it is given or the resource attribute otherwise.
If both the resource attribute and inline content are provided, the inline content takes precedence.
The only valid inline content for import is the instance element. The use case for inline import content is
to allow for save and restore of long-running forms where instance content is originally obtained following resource links
but then to be restored from locally saved inline data. Processors should construct instance content inline within import
elements when saving such forms for later continuation.
| Editorial note: Saving recursively imported instance data | |
| When imported model content contains nested imports, where should processors save instance data for later restore?
Options could include at the root model level regardless of import nesting, in separate documents (ugly), or within the root
importing element (not clear this is better than just at the root document level). |
When importing model content by a link (from src or resource), then the model is extended by consuming the linked resource as follows. The root of the linked resource must be
an XForms model element. Imported attributes from external model elements are transferred to the referencing model element and
processed as though originally authored there. Note that src and resource attributes are allowed on external
model definitions provided they do not result in cyclical references.
As in the use of src and resource on model elements, the content model for externally referenced models is identical to that of local content. Foreign namespaced elements and attributes are not supported
by the core structure of XForms but may be defined by extension processors.
Child content of external model elements is imported into the referencing model and processed as though originally authored there.
The containing import element does not imply any scoping or other behaviorial difference with respect to model content
obtained from external resources.
| Editorial note: Position of saved imported instance data | |
When saving model instance data for subsequent reloading according to the resource processing rules above, instance declarations
and current instance data may be written as direct children of the root model, regardless of the original the import nesting structure.
Since all imported content behaves as authored at the root level, on reload subsequent src or resource attributes
will override content as indicated relative to the corresponding instance content as found at the root level.
Note that the override of saved instance content by reloading imported content with src implies also that multiple imports
referencing the same instance id, or mixed inline and external instances with the same id, will result in overridden content as well.
|
If the link cannot be traversed, then processing halts after dispatching an xforms-link-exception with a resource-uri of the link that failed.