Blog OpenSearch: A Structured Search Service


thammond – 2009 October 05

In Search

(Click panels in figure to read related posts.) Following up on my earlier posts here about the structured search technologies OpenSearch and SRU, I wanted to reference three recent posts on our web publishing blog Nascent which discuss our new OpenSearch service: 1. Service Describes the new OpenSearch service which provides a structured resource discovery facility for content hosted on 2. Clients Points to a small gallery of demo web clients for nature.

Please join us for the 2009 Crossref Technical Meeting.

Anna Tolwinska

Anna Tolwinska – 2009 September 08

In News Release

Crossref Technical Meeting* The Charles Hotel, Cambridge, MA Monday, November 9th, 2009 2:00 pm - 5:00 pm Please register today! We also encourage you to register for our 10th Anniversary Celebration Dinner, which will take place Monday, November 9th, 2009 at 6:30 pm following the Crossref Technical Meeting at the Museum of Science in Boston, MA. Transportation from the Charles Hotel to the Museum of Science will be provided. Our 2009 Annual Meeting will take place on Tuesday, November 10th at 9:00 am in the Charles Hotel in Cambridge, MA and we urge you to register soon (if you haven’t already done so)

PRC Report and “iPub” revisited

Geoffrey Bilder

Geoffrey Bilder – 2009 September 07

In Ipub

OK, so this has nothing to do with any Crossref projects- but there is an interesting new PRC report out by Mark Ware in which he explores how SMEs (small/medium-sized enterprises) make use of scholarly articles and whether the scholarly publishing industry is doing anything to make their lives easier. This is a topic that is close to my heart. For the past few years I’ve been saying (most recently at SSP09) that I think scholarly publishers are much too quick to dismiss the possibility of creating an iTunes-like service for scholarly publications (aka “iPub”).

Crossref is hiring an R&D Developer in Oxford

Geoffrey Bilder

Geoffrey Bilder – 2009 August 20

In News Release

We are looking to hire an R&D Developer in our Oxford offices. We are look for somebody who: Is passionate about creating tools for online scholarly communication. Relishes working with metadata. Has experience delivering web-based applications using agile methodologies. Wants to learn new skills and work with a variety of programming languages. Enjoys working with a small, geographically dispersed team. Groks mixed-content model XML. Groks RDF. Groks REST. Has explored MapReduce-based database systems.

Strategic Reading

Geoffrey Bilder

Geoffrey Bilder – 2009 August 14

In Publishing

Allen Renear and Carole Palmer have just published an article titled “Strategic Reading, Ontologies, and the Future of Scientific Publishing” in the current issue of Science ( I’m particularly happy to see this paper published because I actually got to witness the genesis of these ideas in my living room back in 2006. Since then, Allen and Carole’s ideas have profoundly influenced my thinking on the application of technology to scholarly communication.

OpenSearch Formats for Review


thammond – 2009 July 23

In Search

In an earlier post I talked about using the PAM (PRISM Aggregator Message) schema for an SRU result set. I have also noted in another post that a Search Web Service could support both SRU and OpenSearch interfaces. This does then beg the question of what a corresponding OpenSearch result set might look like for such a record. Based on the OpenSearch spec and also on a new Atom extension for SRU, I have contrived to show how a PAM record might be returned in a coomon OpenSearch format.

OASIS Drafts of SRU 2.0 and CQL 2.0


thammond – 2009 July 22

In Search

As posted here on the SRU Implementors list, the OASIS Search Web Services Technical Committee has announced the release of drafts of SRU and CQL version 2.0: sru-2-0-draft.doc cql-2-0-draft.doc The Committee is soliciting feedback on these two documents. Comments should be posted to the SRU list by August 13.

Crossref OpenURL resolver

Chuck Koscher

Chuck Koscher – 2009 July 07

In Openurl

A new version of our OpenURL resolver was deployed July 2 which should handle higher traffic (e.g. we have re-enable the LibX plug-in ) Unfortunately there were a few hick ups with the new version which I believe are now corrected (a character encoding bug and a XML structure translation problem). Sorry for any inconvenience.

XMP Primer


thammond – 2009 June 10


There’s a new XMP Primer (PDF) by Ron Roskiewicz (ed. Dianne Kennedy) available from XMP-Open. This is copyrighted 2008 but I only just saw this now. This is a 43 page document which provides a very gentle introduction to metadata and labelling of media and then introduces XMP into the content lifecycle and talks to the business case for using XMP. The primer covers the following areas: Introduction to Metadata Introduction to XMP XMP and the Content Lifecycle XMP in Action; Use Cases Additional XMP Resources One small gripe would be that this seems to have been prepared for US letter-sized pages and although is printable on A4 there is the slightest of clippings on the right-hand margin with no real loss of information but it does confer a sense of “incompleteness”.

Aligning OpenSearch and SRU


thammond – 2009 June 05

In Search

[Update - 2009.06.07: As pointed out by Todd Carpenter of NISO (see comments below) the phrase “SRU by contrast is an initiative to update Z39.50 for the Web” is inaccurate. I should have said “By contrast SRU is an initiative recognized by ZING (Z39.50 International Next Generation) to bring Z39.50 functionality into the mainstream Web“.]

[Update - 2009.06.08: Bizarrely I find in mentioning query languages below that I omitted to mention SQL. I don’t know what that means. Probably just that there’s no Web-based API. And that again it’s tied to a particular technology - RDBMS.]


(Click image to enlarge.)

There are two well-known public search APIs for generic Web-based search: OpenSearch and SRU. (Note that the key term here is “generic”, so neither Solr/Lucene nor XQuery really qualify for that slot. Also, I am concentrating here on “classic” query languages rather than on semantic query languages such as SPARQL.)

OpenSearch was created by Amazon’s and is a cheap and cheerful means to interface to a search service by declaring a template URL and returning a structured XML format. It therefore allows for structured result sets while placing no constraints on the query string. As outlined in my earlier post Search Web Service, there is support for search operation control parameters (pagination, encoding, etc.), but no inroads are made into the query string itself which is regarded as opaque.

SRU by contrast is an initiative to update Z39.50 for the Web and is firmly focussed on structured queries and responses. Specifically a query can be expressed in the high-level query language CQL which is independent of any underlying implementation. Result records are returned using any declared W3C XML Schema format and are transported within a defined XML wrapper format for SRU. (Note that the SRU 2.0 draft provides support for arbitrary result formats based on media type.)

One can summarize the respective OpenSearch and SRU functionalities as in this table:

Structure OpenSearch SRU
query no yes
results yes yes
control yes yes
diagnostics no yes

What I wanted to discuss here was the OpenSearch and SRU interfaces to a Search Web Service such as outlined in my previous post. The diagram at top of this post shows query forms for OpenSearch and SRU and associated result types. The Search Web Service is taken to be exposing an SRU interface. It might be simplest to walk through each of the cases.

(Continues below.)

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