From what I understand, "recordPacking" was trying to carry information
of what Z39.50 OIDs did in 1.2.840.10003.5.109.x
http://www.loc.gov/z3950/agency/defns/oids.html

But today, is there any SRU service which is not working over HTTP (I
do not mean Z39.50 over SRU)?

There is the MIME type application/sru+xml
https://tools.ietf.org/html/rfc6207 which is also meant for use in
the HTTP header "Accept" for content negotation.

I think it's time for SRU / SearchRetrieve to fully embrace HTTP
content negotiation, and REST - I mean, most importantly, the HTTP
status codes. Therefore, I would welcome deprecating the parameter
"recordPacking", and also "recordSchema". 

If content negotiation is not sufficient, it could be an option to use
HTTP headers for additional hinting, for XML schemas, bibliographic
field formats etc. HTTP headers could also carry Z39.50 OIDs in their
full extent, by preceding the header name with something like
"X-Z3950-...", or optional SRU parameters, in "X-SRU-..."

Here's my proposal. This is an SRU request for XML

GET /sru/...
Host: localhost
Accept: application/sru+xml
->
HTTP/1.1 200 OK
Content-Type: application/sru+xml

and this is for JSON

GET /sru/...
Host: localhost
Accept: application/sru+json
->
HTTP/1.1 200 OK
Content-Type: application/sru+json

or even, with HTTP content negotiation, both are possible:

GET /sru/...
Host: localhost
Accept: application/sru+xml,application/sru+json
->
HTTP/1.1 200 OK
Content-Type: application/sru+xml

And also something for RDF serializations, because Bibframe is coming
close.

I have only JSON-LD, so over the SRU endpoint, I would also like to
perform RESTful actions on RDF graphs, like

GET /sru/...
Host: localhost
Accept: application/ld+json
->
HTTP/1.1 200 OK
Content-Type: application/ld+json

Such requests lack any information about "recordSchema",
"recordPacking", OIDs, Z39.50, simply because there is none such
information. If it was, it's all encoded in the JSON-LD.

HTTP GET requests are stateless. So I'd like to drop SRU parameter
"resultSetTTL". Was this ever used, clients enforcing servers to keep
result sets, for days or weeks, or even longer? If so, it could be
replaced by URL- or cookie-based session life times, under control of
the server.

Best,

Jörg


>>> "LeVan,Ralph" <[log in to unmask]> schrieb am 17.02.2014 um 21.27 Uhr
in Nachricht
<[log in to unmask]>:
> I'm playing around with JSON and SRU.  My server has pretty decent
support 
> for content negotiation and I've started explaining to it how to
handle 
> requests for JSON.
> 
>
http://rdap02pxdu.dev.oclc.org:8080/viaf/search?query=local.names+all+%22ral
> ph%20levan%22&httpAccept=application/json
> 
> That's a simple name search, with a request that the response be in
JSON.  
> You'll notice that the recordPacking is "xml", which is appropriate,
because 
> the records are returned as XML.  But, as far as JSON is concerned,
what I 
> returned was a string.  (The value of recordData in JSON is of type
string.)  
> What happens if I want to return JSON records?  How do I even ask for
JSON 
> records?
> 
> Right now, to return JSON records I have to say that the
recordPacking is 
> "string" (because it sure isn't "xml") and pick a recordSchema of
JSON 
> (because there's no other place to say you want JSON.
>
http://rdap02pxdu.dev.oclc.org:8080/viaf/search?query=local.names+all+%22ral
>
ph%20levan%22&recordPacking=string&recordSchema=JSON&httpAccept=application/json
> 
> 
> I think the recordPacking was intended to be the mimeType of the
record, as 
> opposed to the httpAccept, which is the mimeType of the response.  I
think 
> the recordSchema was intended to talk about the logical content of
the 
> record, not the physical format.  In my particular case, I already
have 
> multiple schemas that I want to return my data in (LinkedData,
Marc21, 
> VIAFCluster), regardless of the mimeType that the record is returned
in.
> 
> My suggestion is that we expand the meaning of recordPacking to mean

> mimeType of the recordData and grandfather in the special values of
"string" 
> to mean "text/plain" and "xml" to mean "text/xml".  If you return
text/plain 
> records in a text/xml response, it is up to the application to make
the 
> records safe in the XML (meaning escaping the appropriate characters
in the 
> string.)  That same would be expected in JSON (where the string would
just 
> get quotes around it.)
> 
> Does this seem sensible?  Is anyone else doing anything like this?
> 
> Thanks!
> 
> Ralph




-- 
Jörg Prante
hbz, Gruppe Portale
- Digitale Bibliothek und Online-Fernleihe -
Postfach 270451, 50510 Köln, Deutschland
Telefon +49-221-40075-156, Fax +49-221-40075-190
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