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Re: inelegant but working pipeline seeks elegance

From: Conal Tuohy <conal.tuohy@versi.edu.au>
Date: Mon, 12 Mar 2012 17:42:50 +1100
Message-ID: <4F5D9AEA.9080508@versi.edu.au>
To: XProc Dev <xproc-dev@w3.org>
Embarrassing isn't it, when you ask for help and then immediately see a 
better alternative yourself?

I managed to remove the p:choose[@name='whether-to-save-record'] within 
the p:viewport moving the conditional into a predicate in the 
p:viewport's select statement (see below).

I guess I could also convert the resumptionToken handling to use a 
p:viewport rather than a p:choose. The sub-pipeline of the p:viewport 
would run either once (if there were a resumptionToken) or not at all.

Perhaps the rule of thumb I'm looking for is:

To implement a simple "if", always use a p:viewport rather than a 
p:choose (because the  p:otherwise would be a pain).

> <?xml version="1.0"?>
> <p:declare-step
>     version="1.0"
>     xmlns:p="http://www.w3.org/ns/xproc"
>     xmlns:fn="http://www.w3.org/2005/xpath-functions"
>     xmlns:harvester="tag:conal.tuohy@versi.edu.au,2012:oai-pmh"
>     xmlns:oai="http://www.openarchives.org/OAI/2.0/"
>     xmlns:tdar="http://www.tdar.org/namespace"
> >
>
> <harvester:list-records
>         name="harvest"
>         base-uri="http://ahad.edu.au/oai-pmh/oai"
>         base-storage-uri="/tmp/harvest/"
>         metadata-prefix="tdar"/>
>
> <p:declare-step type="harvester:list-records" name="list-records">
> <p:option name="base-uri" required="true"/>
> <p:option name="base-storage-uri" required="true"/>
> <p:option name="metadata-prefix"/>
> <p:option name="resumption-token"/>
> <p:variable name="uri" select="concat($base-uri, 
> '?verb=ListRecords&amp;')"/>
> <!-- query the OAI-PMH server -->
> <p:choose name="resumption-token-or-metadata-prefix">
> <p:when test="p:value-available('resumption-token')">
> <p:load name="query-with-resumption-token">
> <p:with-option name="href" select="concat($uri, 'resumptionToken=', 
> $resumption-token)"/>
> </p:load>
> </p:when>
> <p:otherwise>
> <p:load name="query-with-metadata-prefix">
> <p:with-option name="href" select="concat($uri, 'metadataPrefix=', 
> $metadata-prefix)"/>
> </p:load>
> </p:otherwise>
> </p:choose>
> <p:identity name="query-results"/>
> <p:viewport name="record" 
> match="oai:OAI-PMH/oai:ListRecords/oai:record[oai:metadata[tdar:dataset | 
> tdar:project | tdar:person | tdar:institution | tdar:image | 
> tdar:sensoryData]]">
> <!-- double-encode the record identifier so as to produce URI-encoded 
> file name -->
> <p:variable name="file-name" 
> select="concat(fn:encode-for-uri(fn:encode-for-uri(/oai:record/oai:header/oai:identifier)), 
> '.xml')"/>
> <!-- save the record -->
> <p:store name="save-record" indent="true">
> <p:input port="source" select="oai:record/oai:metadata/*"/>
> <p:with-option name="href" select="concat($base-storage-uri, 
> $file-name)"/>
> </p:store>
> <p:identity>
> <p:input port="source">
> <p:pipe step="save-record" port="result"/>
> </p:input>
> </p:identity>
> </p:viewport>
>
> <!-- query again (recursively) if a resumptionToken was returned in 
> the query results -->
> <p:choose name="whether-to-resume-query">
> <p:variable name="resumption-token-returned" 
> select="/oai:OAI-PMH/oai:ListRecords/oai:resumptionToken"/>
> <p:when test="normalize-space($resumption-token-returned)">
> <harvester:list-records>
> <p:with-option name="base-uri" select="$base-uri"/>
> <p:with-option name="base-storage-uri" select="$base-storage-uri"/>
> <p:with-option name="resumption-token" 
> select="$resumption-token-returned"/>
> </harvester:list-records>
> </p:when>
> <p:otherwise>
> <!-- no resumption token (or empty resumption token) returned; nothing 
> to do -->
> <p:identity name="dummy1"/>
> <p:sink name="dummy2"/>
> </p:otherwise>
> </p:choose>
>
> </p:declare-step>
>
> </p:declare-step>



-- 
Conal Tuohy
eResearch Business Analyst
Victorian eResearch Strategic Initiative
+61-466324297
Received on Monday, 12 March 2012 06:43:26 GMT

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