Language element reference

This reference describes the details of the language elements in the XML schema for the Active Correlation Technology rule language. The language elements are listed in alphabetical order, and the attributes that are available for each element are described within the topic for that element.

In XML, and in other markup languages such as SGML and HTML, an element is a basic unit that consists of a start tag, end tag, associated attributes and their values, and any text that is contained between the start and end tags. An attribute is a name-value pair that is coded on an element to define a certain characteristic of the element. An attribute has a data type that identifies the kind of information that is provided in its value (for example, numerical, textual, or boolean information).

In XML, a namespace is a uniform resource identifier (URI) that provides a unique name to associate with the elements and type definitions in a schema. The URI indicates which XML schema contains the definition of an element. A namespace is specified with a prefix string followed by a colon. The Active Correlation Technology rule language schema is defined in three different files and uses the following three namespaces:
xsd:
This namespace indicates that the language element is defined in the standard XML schema, which is described at http://www.w3.org.
br:
This namespace indicates that the language element is defined in the Active Correlation Technology base rule set schema, which is in the ACTparser.jar file in the com/ibm/correlation/ruleparser/xml/RuleSetBase.xsd subdirectory. For example, br:ruleSet refers to the ruleSet element that is defined in the RuleSetBase.xsd file.
act:
This namespace indicates that the language element is defined in the Active Correlation Technology language schema, which is in the ACTparser.jar file in the com/ibm/correlation/ruleparser/xml/ACTL.xsd subdirectory. For example, act:ruleSet refers to the ruleSet element that is defined in the ACTL.xsd file.
In the rule language schema, language elements are defined as either elements or complex types, for example:
<xsd:element name="symbol" minOccurs="1" maxOccurs="unbounded"></element>
<xsd:complexType name="symbol"></complexType>

In the schema, the minOccurs and maxOccurs attributes define the minimum and maximum number of occurrences, respectively, for a language element. Table 1 describes the meaning of different values for the minOccurs and maxOccurs attributes.

Table 1. Attributes in the schema that define the number of occurrences for a language element
Attribute Attribute value Meaning
minOccurs 0 The language element is optional.
minOccurs 1 The language element must occur at least once. 1 is the default value for the minOccurs attribute.
minOccurs 2 The language element must occur at least twice.
maxOccurs 1 The language element cannot occur more than once. 1 is the default value for the maxOccurs attribute.
maxOccurs unbounded The language element can occur any number of times.