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Purls vs handles

Building on yesterday’s post on Critical GPO systems and the FDLP cloud, I’ve done a little digging into GPO’s proposed migration from [w:Purl]s to the use of “handles.” According to RFP 3650 “Handle system overview,”

The Handle System includes an open protocol, a namespace, and a reference implementation of the protocol. The protocol enables a distributed computer system to store names, or handles, of digital resources and resolve those handles into the information necessary to locate, access, and otherwise make use of the resources. These associated values can be changed as needed to reflect the current state of the identified resource without changing the handle. This allows the name of the item to persist over changes of location and other current state information. Each handle may have its own administrator(s) and administration can be done in a distributed environment (my emphasis). The Handle System supports secured handle resolution. Security services such as data confidentiality, data integrity, and non-repudiation are provided upon client request.

Purls and handles do roughly the same thing: they’re link resolvers. But, as Larry Stone’s 2000 article for MIT’s Persistent Naming discovery project, “Competitive Evaluation of PURLs” points out, there are differences that make handles a better choice for long-term operation and persistence. Without getting too technical, handles are not connected to any protocol (i.e., [w:HTTP]) or domain (i.e., .gov) and can therefore work regardless of the network design or protocol used. This is extremely important for scalability and persistence over the long term. In addition, handles can do more than resolve to URLs. “The Handle System design allows for various other types of resolution objects, metadata, and extensible addtions to each Handle object record.”

In short, handles are more persistent, more scaleable, and can do more. But most importantly in my mind, handle administration, “can be done in a distributed environment.” This makes handles perfect for the FDLP cloud because the work of resolving links can be done in a distributed environment. So I say, kudos to GPO for moving to the handle system.

Oh, hold that applause for a moment. My search also turned up the following document from Fall 2007 Depository Library Council meeting entitled, “Handles Council Briefing Topic” (PDF). This briefing document basically describes what I’ve just said above and describes a gradual transition/migration from purls to handles with an anticipated timeline to, “coincide with Release 1-C of FDsys in 2008.” There’s a March, 6 2008 report, “Report on the handles beta test” that calls the handles beta test “satisfactory.” But no information is available after that report. So what happened?

I know the building of FDsys has been no easy task and that GPO staff have worked really hard to keep to their published release schedule; but I’d like to know why the handles migration didn’t occur in 2008. If more testing is involved, I’m sure there are libraries that would be willing to be beta-beta testers for handles. Perhaps this is an opportune time to finally implement the migration to the handles system.

–that is all.

CC BY-NC-SA 4.0 This work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License.


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