The following operations and components are using this information:
SOAP Adapter and SOAP Services exchanging document style/literal encoded messages.
- Blob operation:
xmlToClass()
- String operation:
xmlToClass()
- Any type operation:
classToXML()
Controlling the Mapping by Stereotypes
Stereotypes control how UML class properties (attributes and association ends) are serialized to an XML Document. If no stereotype is assigned, the following default rules apply for mapping XML to UML classes (xmlToClass()
):
- XML attributes are mapped to class attributes.
- XML elements are mapped to class associations ends.
- The XML root element is named according to the definitions in the service composite, tagged value Class To XML Default Root Name.
The following stereotypes are available:
Stereotype | Description | Tagged Values (Description see below) |
---|---|---|
<<XML>> | Set this basic stereotype on class level to be able to apply the stereotypes listed below to the attributes. | xmlNamespace xmlElementName isMixed isOrdered |
<<XMLElement>> | UML properties are mapped to XML elements. | xmlNamespace xmlForm xmlFormat isNillable |
<<XMLAttribute>> | UML properties having a simple type are mapped to XML attributes. | xmlNamespace xmlForm xmlFormat |
<<E2EAttribute>> | This stereotype can be used to specify an order for the generation of XML elements. | order |
<<XMLNamespace>> | UML properties having a simple type are mapped to XML namespaces. The prefix of the namespace is given by the property name. If the same namespace is declared more than once, the runtime will suppress namespaces further down the XML hierarchy, if prefix and namespace are identical. If not, the xUML Runtime will throw an exception. | |
<<XMLCharacters>> | UML properties having a simple type are serialized as a character stream. | xmlFormat |
Tagged Values
Tagged Value | Level | Description | Allowed Values | |
---|---|---|---|---|
classToXMLDefaultRootName | Composite | Bridge 7 Specify which name to assign to the XML root element upon serializing. This setting can be overridden by using XML composer options as described on classToXML() Operation. | Default | Try to use name and namespace defined on the class by the <<XML>> stereotype. Fallback to Variable Name if not provided (default). |
Type Name | Use static name and namespace of the class as name of XML root element. | |||
Variable Name | Use the name of the reference (object/variable) as name of XML root element. | |||
xmlNamespace | Class | Specify the XML namespace. | a valid namespace | |
xmlElementName | Class | Specify the name of the XML root element. | a valid element name | |
isMixed | Class | Specify whether the XML contains mixed (static and variable) content. For more information on mixed content, refer to Mixed Content. | true | XML contains mixed content. |
false | XML does not contain mixed content (default). | |||
isOrdered | Class | Specify whether the class attributes should be serialized to XML using the order tag that has been specified on the attributes. | true | Serialize in order of order tags from the attributes. |
false | Serialize in order of attributes on class. | |||
xmlNamespace | Attribute | Each XML attribute and element may have its own namespace. If the tagged value contains an URI, the runtime will automatically generate a unique prefix. For example: A tagged value xmlNamespace = "http://e2e.ch" on the UML property anElement will result in the XML document<ns0:anElement xmlns:ns0="http://e2e.ch"> .However, it is possible to define the prefix by using the following syntax: 'xmlns:' <prefix name> '=' <namespace uri> . For example, the tagged value xmlNamespace = 'xmlns:typens="http://e2e.ch"' of the UML property anElement will lead to the following XML fragment: <typens:anElement xmlns:typens="http://e2e.ch"> . | an URI | |
a valid xlmns syntax | ||||
xmlForm | Attribute | Depending on this tagged value, XML elements or attributes may not be qualified by a namespace prefix even if they have one. | qualified | The element or attribute must always be qualified by a namespace prefix. Default for XML elements. |
unqualified | No namespace prefixes are allowed (for details see http://www.w3.org/TR/xmlschema-0/#NS). Default for XML attributes. | |||
xmlFormat | Attribute | If numbers and date/time types are parsed or composed, the XML parser respectively composer expects simple date types following the XML schema specification. However, legacy XML documents may contain different number and date/time formats. In this case, the tagged value xmlFormat may hold a format string. If numbers are parsed or composed use the format strings defined in section Number Formatting. If date/time expressions must be parsed or composed, use the format strings defined in Date and Time Formatting. Use xmlFormat = "CDATA" together with stereotype <<XMLElement>> to compose strings as CDATA with
classToXML() . Parse CDATA elements works out of the box, you do not need to set xmlFormat. | a valid format string (see Number Formatting or Date and Time Formatting) | |
CDATA | compose string as CDATA | |||
isNillable | Attribute | By default, UML properties that are NULL are not serialized into XML documents. However, if it is necessary to do so, isNillable must be set to true. In this case, the UML properties being NULL will look like: | true | serialize NULL properties |
false (default) | do not serialize NULL properties | |||
order | Attribute | Use this tagged value of <<E2EAttribute>> to specify the order in which the XML elements will be generated to the XML document. | a valid float |
XML Serialization
The behavior of XML serialization is not always self-explanatory but a consequence of the definition of arrays in XML schema.
The following table shows the behavior of XML serialization for the example:
{ "aClass" : { "anArray" : ["A1", "A2", "A3"] }; }
Description | XML result |
---|---|
All values are present. | <aClass> <anArray>A1</anArray> <anArray>A2</anArray> <anArray>A3</anArray> </aClass> |
The second value (A2) is NULL and isNillable=false. | <aClass> <anArray>A1</anArray> <anArray>A3</anArray> </aClass> |
The second value (A2) is NULL and isNillable=true | <aClass xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"> <anArray>A1</anArray> <anArray xsi:nil="true"/> <anArray>A3</anArray> </aClass> |
The array is NULL. | <aClass> </aClass> |
The array is empty. | <aClass> </aClass> |
All elements are NULL and isNillable=false. | <aClass> </aClass> |
All elements are NULL and isNillable=true. | <aClass xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"> <anArray xsi:nil="true"/> <anArray xsi:nil="true"/> <anArray xsi:nil="true"/> </aClass> |
classToXMLDefaultRootName="Default" and xmlElementName="anotherClass". | <anotherClass> <anArray>A1</anArray> <anArray>A2</anArray> <anArray>A3</anArray> </anotherClass> |
classToXMLDefaultRootName="Type Name" and xmlElementName="anotherClass". | <AClassType> <anArray>A1</anArray> <anArray>A2</anArray> <anArray>A3</anArray> </AClassType> |
classToXMLDefaultRootName="Variable Name" and xmlElementName="anotherClass". | <aClass> <anArray>A1</anArray> <anArray>A2</anArray> <anArray>A3</anArray> </aClass> |
Examples
Suppose an XML data structure contains elements with attribute values (in the example below these are street and city), and you want to convert them to an UML class.
<address id="myAddress"> <street id="234">Lautengartenstr. 12</street> <city id="34">Basel</city> </address>
The class diagram below illustrates how to map the content of the XML element street ("Lautengartenstr. 12") and the value of its attribute id ("234") to the UML association end street:
Figure: Mapping XML Data Structures to UML Classes
The street element from the above XML example is mapped to the association end street. The association end name must be the same as the name of the XML element. The associated class StreetElement is only a container for the street element. The name of the class is not relevant for the mapping. The XML attribute id of the element street is mapped to the class attribute id of the UML class StreetElement. The content of the XML element street is mapped to the class attribute text_value, which has the stereotype <<XMLCharacters>>.
If the XML element contains attributes, which should not be mapped to UML class attributes, an association to a base type can be used. The following example shows this for the element city. The content of the element ("Basel") will be available in city (accessible as attribute of the instantiated class Address2Example1). As the id attribute cannot be mapped, it will be discarded when executing the operation xmlToClass()
.
Figure: Preventing the Mapping of XML Attributes
Below, find the complete class diagram used for mapping the XML document address.xml.
Figure: Example when Using Operation xmlToClass()
If an object of class Address2Example1 were serialized back in a SOAP response, the SOAP message would read:
<address2Example1 xmlns:ns1="urn:Services.URLService.URLPort.DataItems" xsi:type="ns1:Address2Example1"> <id xsi:type="xsd:string">34</id> <street xsi:type="ns1:StreetElement"> <id xsi:type="xsd:string">234</id> <text_value xsi:type="xsd:string">Lautengartenstr. 12 </text_value> </street> <city xsi:type="xsd:string">Basel</city> </address2Example1>
The same result could be obtained with the following class diagram.
Figure: Class Diagram with XML Stereotypes
With the three XML stereotypes, one has the flexibility to map XML structures in different ways. You can define very compact class diagrams for simple XML structures, but you have also the possibility to map complex XML data structures graphically.