Xscan

Processes streaming XML data based on input path expressions and returns a relation consisting of attribute-value bindings.

Usage

xscan (paths, xmldata : bindings)

Details

Returns all attribute-value bindings found in an XML data stream. Attributes are derived from paths, both relative and absolute, passed as input to the operator. Output attribute names are extracted from the attribute name of its corresponding paths expression.

Notes

Paths is a relation where each tuple consists of a path expression, either relative or absolute.
XMLdata must be a valid XML document passed in through a relation made up of one tuple consisting of one column.

Known Bugs

None

Example

Using the input:

      RELATION x: path char
      //lab/name
      //location

      RELATION y: xml char
      <db>
        <lab ID="baselab" manager="smith1">
          <name>Seattle Bio Lab</name>
            <location>
              <city>Seattle</city>
              <country>USA</country>
           </location>
      	</lab>
      	<lab ID="lab2">
           <name>PMBL</name>
           <city>Philadelphia</city>
           <country>USA</country>
      	</lab>
         <paper ID="Smith991231" source="baselab" biologist="smith1">
           <title>Autocatalysis of Spectral...</title>
         </paper>
         <biologist ID="smith1">
           <lastname>Smith</lastname>
         </biologist>
      </db>

when executing the plan:

      PLAN c
      {
        INPUT: stream x,stream y
        OUTPUT: stream z

        BODY
        {
      	xscan(x,y:z)
        }
      }

will generate the following output:

 	----------------------------------------------
	RELATION: scan_z
		    attrs: name, location
	----------------------------------------------
	Seattle Bio Lab|<city>Seattle</city><country>USA</country>
	PMBL|
	----------------------------------------------