XMLStructure

The simple property XMLStructure identifies the potential structure of the XML elements that are represented by fields in a Record part. In this topic, we show examples that describe what happens when you transfer record data to an XML string. However, the relationships also apply in the opposite direction, when the EGL Runtime validates the transfer of an XML string to an input record.

The supported values for XMLStructure are as follows:

sequence (the default)

On output, the XML string must include every field in the Record part, in the order in which the Record fields are listed. The following Record part and XML string are related:

Record Employee {XMLStructure = XMLStructureKind.sequence}
   EmpNo INT;
   LastName STRING;
end

<Employee>
   <EmpNo>10</EmpNo>
   <LastName>Smith</LastName> 
</Employee>

choice

On output, the XML string must include one and only one subordinate element that corresponds to a record field. For example, consider the following Record part:

Record Employee{XMLStructure = XMLStructureKind.choice}
   ImmigrationStatus STRING?; 
   YearsOfCitizenship INT?;
end

Either of the following XML strings is valid:

<Employee>
   <ImmigrationStatus>A1</ImmigrationStatus>
</Employee>

<Employee>
   <YearsOfCitizenship>20</YearsOfCitizenship>
</Employee>

In this case, the XML string cannot include both kinds of elements.

If a record has the XMLStructure value "choice", each field must be nullable, as is indicated by the question marks in our example. Furthermore, the value of one field must be non-null, and the value of only one field can be non-null. The function XMLLib.convertToXML issues a RuntimeException if all fields in the input record are null or if more than one field is non-null.

simpleContent

On output, the simple content transferred to an XML string is the value of a field in a superior record, along with a set of attributes. For example, the following boldface Record part and XML content are related:

Record Employee{XMLStructure = XMLStructureKind.sequence}
   EmpNo EmpNumber;
   LastName STRING;
end

Record EmpNumber {XMLStructure = XMLStructureKind.simpleContent}
  	department STRING {@XMLAttribute{}};
  	value INT; // any field name is acceptable here
end
<Employee>
   <EmpNo department="Sales">10</EmpNo>
   <LastName>Smith</LastName> 
</Employee>

The subordinate record (here, EmpNumber) may include zero to many fields that are of type STRING and that have the property @XMLAttribute. The property indicates that a given field represents an attribute. The same subordinate record may have a field that lacks the property @XMLAttribute; and that non-attribute field, if any, holds the value of the related element. The non-attribute field may have any name.

unordered

The XML string includes the specified elements in any order. The following Record part describes either of the subsequent XML strings:

Record Employee {XMLStructure = XMLStructureKind.unordered}
   EmpNo INT;
   LastName STRING;
end

<Employee>
   <LastName>Jones</LastName> 
   <EmpNo>20</EmpNo>
</Employee>

<Employee>
   <EmpNo>20</EmpNo>
   <LastName>Jones</LastName> 
</Employee>

Those values constitute the enumeration xmlStructureKind.