STRING DIGEST

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.

Examples

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>