STRING expressions return text strings. They are
used to manipulate non-numeric data. The
STRING DIGEST expression creates a property identifier
that is a digest of a specified
PROP_NAME expression node.
STRING DIGEST generates Message Digest 5 (MD5) digest
strings, also called MD5 hashes and message digests. A
STRING DIGEST expression requires a
PROP_NAME expression node. Typically, a file name is
generated using a
STRING DIGEST of the
Endeca.Identifier property.
See the
EXPRESSION element for DTD and attribute information.
This example creates a digest identifier based on the
Endeca.Identifier property.
<EXPRESSION TYPE="STRING" NAME="DIGEST">
<EXPRESSION TYPE="PROPERTY" NAME="IDENTITY">
<EXPRNODE NAME="PROP_NAME" VALUE="Endeca.Identifier"/>
</EXPRESSION>
</EXPRESSION>
This example shows how to use a
STRING DIGEST expression as a sub-expression of the
VOID RETRIEVE_URL expression, which is used to
retrieve a document from its URL and store it in a file on disk.
<EXPRESSION LABEL="" NAME="RETRIEVE_URL" TYPE="VOID" URL="">
<COMMENT>Retrieve the document and store it as a temporary
file in the state directory, named with the digest (MD5 hash)
of its URL.
</COMMENT>
<EXPRESSION LABEL="" NAME="CONCAT" TYPE="STRING" URL="">
<EXPRESSION LABEL="" NAME="CONST" TYPE="STRING" URL="">
<EXPRNODE NAME="VALUE" VALUE="../partition0/state/"/>
</EXPRESSION>
<EXPRESSION TYPE="STRING" NAME="DIGEST">
<EXPRESSION TYPE="PROPERTY" NAME="IDENTITY">
<EXPRNODE NAME="PROP_NAME" VALUE="Endeca.Identifier"/>
</EXPRESSION>
</EXPRESSION>
</EXPRESSION>
</EXPRESSION>
