Identifiers
Identifiers can refer to the values of message headers and properties, but not to the message body. Identifiers are case-sensitive.
- Basic Syntax
An identifier is a sequence of letters and digits, of any length, that begins with a letter. As in Java, the set of letters includes _ (underscore) and $ (dollar).
- Illegal
Certain names are exceptions, which cannot be used as identifiers. In particular,
NULL
,TRUE
,FALSE
,NOT
,AND
,OR
,BETWEEN
,LIKE
,IN
,IS
, andESCAPE
are defined to have special meaning in message selector syntax. - Value
Identifiers refer either to message header names or property names. The type of an identifier in a message selector corresponds to the type of the header or property value. If an identifier refers to a header or property that does not exist in a message, its value is
NULL
.