Apparently, listserv problems, and Tony asked me to forward this.


From: Hammond, Tony [mailto:[log in to unmask]]
Sent: Wednesday, February 19, 2014 12:34 PM
To: Denenberg, Ray
Subject: Fwd: SRU recordPacking and JSON


Hi Ray:


I don't know if I'm failing to post to the list. Can't see it listed there. Would it be possible for you to forward if it doesn't show up?






Begin forwarded message:

From: "Hammond, Tony" <[log in to unmask]>
Date: 19 February 2014 16:50:59 GMT
To: "SRU (Search and Retrieve Via URL) Implementors" <[log in to unmask]>
Cc: Ray Denenberg <[log in to unmask]>
Subject: Re: SRU recordPacking and JSON

Hi Ray:


Thanks for summarizing. Have been scratching my head too to remember what this was all about. But it's all in the archive. T:)


This message is perhaps appropriate - not least because the links still work after 4 years - and because our service is still working (albeit performance may be an issue):


The basic idea was that this parameter had been misnamed earlier and that it could help us with a problem in which data was too deeply nested in a structured instance because of the (standards-based) schema we were attempting to follow.  We suggested that it could serve as a "hint" to the server to unpack a deeply nested structure which would make more sense in lightweight serializations such as RSS, JSON, etc.


The previous SRU 1.2 purpose of this parameter was targeted at differentiating between XML and text representations, I believe - a functionality which was superseded by SRU 2.0's support for generalized content negotiation.





From: Ray Denenberg <[log in to unmask]>
Reply-To: "SRU (Search and Retrieve Via URL) Implementors" <[log in to unmask]>
Date: Wednesday, 19 February 2014 15:17
To: "[log in to unmask]" <[log in to unmask]>
Subject: Re: SRU recordPacking and JSON


Hi John - I'll try to summarize the thinking behind this. As soon as I have some time I'll go to the archive and re-read the discussion and then give a fuller explanation.   


At the time that the packing parameter was discussed there were seven or eight members on the committee. One member felt very strongly about the issue and was able to convince the rest of the members.  (That was Tony Hammond of, whose contribution to the standard was significant.) 


Tony  argued for the case where records normally consist of structure and payload (not the norm for bibliographic data,  more normal for  there will be cases where a server has content that it is willing and able to provide but is either not willing or not able to supply the syntactic infrastructure …or…   the server is willing to supply the data according to the requested schema, but is also willing to supply it "unpacked" (Tony's term), and that alternative would be cheaper and quicker.   So, the client says,  I want the data supplied according to schema XYZ, however supply it unpacked, if you can, or if you cannot supply it according to XYZ. (This of course presumes that the client is able to extract the payload from the unpacked data, or at least try to, and how that happens is not addressed.)


I completely agree that this is not adequately described in the standard.  I think we can add an explanation to "Implementer Notes" (which we haven't started yet, but will).





From: SRU (Search and Retrieve Via URL) Implementors [mailto:[log in to unmask]] On Behalf Of John Harrison
Sent: Wednesday, February 19, 2014 4:16 AM
To: [log in to unmask]
Subject: Re: SRU recordPacking and JSON



On 18 Feb 2014, at 18:40, Ray Denenberg <[log in to unmask]> wrote:

The recordPacking parameter in 2.0 has completely different meaning than in 1.2.    (See 13.2 copied below.) In short, it tells the server whether or not to take seriously the parameter recordSchema: if it is omitted or its value is 'packed' then the server MUST supply records according to the requested schema.  If it is supplied with the value 'unpacked' then the server is free to choose an alternative schema.


Wow, this is confusing. I could understand repurposing an existing parameter if the new purpose was accurately summarised by the existing parameter name, but that doesn't seem to be the case here. I mean that the name 'recordPacking' does not intuitively suggest that the purpose is to say whether the server MUST return in the requested schema (or presumably return a diagnostic). Can someone explain the logic behind this choice?






John Harrison

University of Liverpool

t: 0151 7943921




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