perfSONAR_PS::DB::File - A module that provides methods for adding 'database like' functions to files that contain XML markup.


This purpose of this module is to ease the burden for someone who simply wishes to use a flat file as an XML database. It should be known that this is not recommended as performance will no doubt suffer, but the ability to do so can be valuable. The module is to be treated as an object, where each instance of the object represents a direct connection to a file. Each method may then be invoked on the object for the specific database.

new($package, { file })

The only argument is a string representing the file to be opened.

setFile($self, { file })

(Re-)Sets the name of the file to be used.

openDB($self, { error })

Opens the database, will return status of operation.

closeDB($self, { error })

Close the database, will return status of operation.

query($self, { query, error } )

Given a query, returns the results or nothing.

querySet($self, { query error } )

Given a query, returns the results (as a nodeset) or nothing.

count($self, { query error } )

Counts the results of a query.

getDOM($self, { error } )

Returns the internal XML::LibXML DOM object. Will return "" on error.

setDOM($self, { dom, error } )

Sets the DOM object.


    use perfSONAR_PS::DB::File;
    my $file = new perfSONAR_PS::DB::File(

    # or also:
    # my $file = new perfSONAR_PS::DB::File;
    # $file->setFile("./store.xml");  
    my $parameters->{error} = "";

    print "There are " , $file->count("//nmwg:metadata", $parameters->{error}) , " elements in the file.\n";

    my @results = $file->query("//nmwg:metadata", $parameters->{error});
    foreach my $r (@results) {
      print $r , "\n";

    # If a DOM already exists...
    my $dom = XML::LibXML::Document->new("1.0", "UTF-8");
    $file->setDOM($dom, $parameters->{error});
    # or getting back the DOM...
    my $dom2 = $file->getDOM($parameters->{error});


XML::LibXML, Log::Log4perl, Params::Validate, perfSONAR_PS::Common

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The perfSONAR-PS subversion repository is located at: 

Questions and comments can be directed to the author, or the mailing list. Bugs, feature requests, and improvements can be directed here:




Jason Zurawski,


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