powershell script to harvest all DC metadata from OAI server. returns xml and csv files

gistfile1.ps1

# define the oai server and base request string
$baseurl = "http://digitalrepository.smu.edu/cgi/oai2.cgi/OAI-script?"
$payload = "verb=ListRecords&metadataPrefix=oai_dc"

# set up the webclient to grab the xml. some servers reject oai-pmh requests with no user-agent specified
$wc = New-Object System.Net.WebClient
$wc.Encoding = [Text.Encoding]::UTF8
$wc.Headers.add("User-Agent", "PowerShell Script")

# set the first request and load the xml into variable. note: this assumes server response is xml
$url = $baseurl + $payload
[xml]$oaicont = $wc.downloadstring($url)

# define the node containing all records. we'll append records from additional pages to this node
$apnode = $oaicont.selectsinglenode("/*/*[local-name()=`"ListRecords`"]")

#find the resumptionToken
$rt = $oaicont.selectsinglenode("/*/*[local-name()=`"ListRecords`"]/*[local-name()=`"resumptionToken`"]")

# do this while found pages have resumptionTokens
while ($rt.haschildnodes -eq $true)
{
    # add a timeout so the OAI server doesn't get mad
    Start-Sleep -s 10

    # set new URL request based on rt, load xml, and get new resumptionToken
    $url = $baseurl + "verb=ListRecords&resumptionToken=" + $rt.innertext
    $wc.Headers.add("User-Agent", "PowerShell Script")
    [xml]$oainext = $wc.downloadstring($url)
    $rt = $oainext.selectsinglenode("/*/*[local-name()=`"ListRecords`"]/*[local-name()=`"resumptionToken`"]")

    # get all additional records and append them to the apnode
    $innerel = $oainext.selectnodes("/*/*[local-name()=`"ListRecords`"]/*")
    foreach ($inone in $innerel) 
    {
        $inone = $oaicont.importnode($inone, $true)
        $apnode.appendchild($inone)
    }
}

# build a pretty printing xml writer
$xws = new-object system.xml.XmlWriterSettings
$xws.Indent = $true
$xws.indentchars = "`t"
$xtw = [system.xml.XmlWriter]::create("path to output xml", $xws)
$oaicont.WriteContentTo($xtw)
$xtw.flush()
$xtw.dispose()

# transform this xml file to csv using the 
$xslt = New-Object System.Xml.Xsl.XslCompiledTransform
$xslt.load( "path to stylesheet, e.g., oai2csv.xsl", [System.Xml.Xsl.XsltSettings]::TrustedXslt, (New-Object System.Xml.XmlUrlResolver) )
$xslt.Transform( "path to output xml", "path to output csv" )