[n2-dev] Finding the URI for a newly created blank node

[Rupert Redington]

Hi All,

As I understand it (which may well be imperfectly), when I post rdf
representing a blank node to a store I can expect (if all goes well)
an HTTP 201 or 202 response which will include a 'Location' header
giving the URI for the newly created node.

However, when I post the following rdf to my store the response is a
204 'No Content'. What have I failed to understand here?

Thanks in advance,

Rupert
NeonTribe

sample.rdf
<?xml version="1.0" encoding="UTF-8"?>
<rdf:RDF
xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
xmlns:rev="http://purl.org/stuff/rev#"
xmlns:rdfs="http://www.w3.org/TR/rdf-schema/"
xmlns:pb="http://plingback.plings.net/ontologies/plingback#"
>
<rdf:Description>
<rdfs:type rdf:resource="http://purl.org/stuff/rev#Review"/>
<pb:plingBackType rdf:resource="http://plingback.plings.net/
applications/fastfeedback"/>
<rev:rating rdf:datatype="http://www.w3.org/2001/
XMLSchema#integer">5</rev:rating>
</rdf:Description>
</rdf:RDF>

curl command (account details redacted):
curl -v --digest -u"***:***" -d @sample.rdf -H content-
type:application/rdf+xml http://api.talis.com/stores/plings-dev2/meta


curl results:
* About to connect() to api.talis.com port 80 (#0)
* Trying 82.147.9.16... connected
* Connected to api.talis.com (82.147.9.16) port 80 (#0)
* Server auth using Digest with user '***'
> POST /stores/plings-dev2/meta HTTP/1.1
> User-Agent: curl/7.19.5 (i486-pc-linux-gnu) libcurl/7.19.5 OpenSSL/0.9.8g zlib/1.2.3.3 libidn/1.15
> Host: api.talis.com
> Accept: */*
> content-type:application/rdf+xml
> Content-Length: 0
>
< HTTP/1.1 401 Unauthorized
< WWW-Authenticate: Digest realm="bigfoot", domain="null",
nonce="********", algorithm=MD5, qop="auth"
< Content-Type: text/plain
< Content-Length: 12
<
* Ignoring the response-body
* Connection #0 to host api.talis.com left intact
* Issue another request to this URL: 'http://api.talis.com/stores/
plings-dev2/meta'
* Re-using existing connection! (#0) with host api.talis.com
* Connected to api.talis.com (82.147.9.16) port 80 (#0)
* Server auth using Digest with user '****'
> POST /stores/plings-dev2/meta HTTP/1.1
> Authorization: Digest username="***", realm="bigfoot", nonce="****", uri="/stores/plings-dev2/meta", cnonce="MDcyODQ0", nc=00000001, qop="auth", response="639ac387f4b70957a758c874f310b2dd", algorithm="MD5"
> User-Agent: curl/7.19.5 (i486-pc-linux-gnu) libcurl/7.19.5 OpenSSL/0.9.8g zlib/1.2.3.3 libidn/1.15
> Host: api.talis.com
> Accept: */*
> content-type:application/rdf+xml
> Content-Length: 556
>
< HTTP/1.1 204 No Content
< Cache-Control: max-age=7200, must-revalidate
< server: Bigfoot/35.1396.60748
<
* Connection #0 to host api.talis.com left intact
* Closing connection #0

--
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Mailing List : http://groups.google.com/group/n2-dev
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[Sam Tunnicliffe]

Hi Rupert,

Successfully posting RDF documents (containing bnodes or not) to a Store via the  /meta uri will always return a 204 response, and the Platform doesn't return any further information about the content of the update. 

The Location header is returned when posting a single changeset, and only when recording that changeset (not just applying the delta it describes), which is done by  POSTing it to /meta/changesets.

In that scenario, the Location header is used to communicate the URI that the Store assigns to the Changeset itself. 

There are further details about this part of the api here: http://n2.talis.com/wiki/Metabox

HTH

Sam

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--
Sam Tunnicliffe
Head of Development, Platform Division
Talis Systems Ltd
http://www.talis.com

[Rupert Redington]

Thanks Sam,

That does clear up my misunderstanding, but leaves me a little
stumped.

It seems there's no way for me to identify the parts of the graph
which were modified by my request if the data doesn't contain any
unique values. I guess the primary key pattern (http://n2.talis.com/
wiki/Primary_Key_Pattern) is my best bet for a solution.

I'm a bit wary of it because of the overhead in requests it imposes,
but also because it seems a duplication of effort, since the nodes
just added to the store have usable identifiers which are guaranteed
to be unique - if only I could find out what they were...

Does anyone have a tip for me?

Rupert

> > type:application/rdf+xmlhttp://api.talis.com/stores/plings-dev2/meta

> > Find out more about Talis athttp://www.talis.com/

> > shared innovation™
>
> > Any views or personal opinions expressed within this email may not be those
> > of Talis Information Ltd or its employees. The content of this email message
> > and any files that may be attached are confidential, and for the usage of
> > the intended recipient only. If you are not the intended recipient, then
> > please return this message to the sender and delete it. Any use of this
> > e-mail by an unauthorised recipient is prohibited.
>
> > Talis Information Ltd is a member of the Talis Group of companies and is
> > registered in England No 3638278 with its registered office at Knights
> > Court, Solihull Parkway, Birmingham Business Park, B37 7YB.
>
> --
> Sam Tunnicliffe
> Head of Development, Platform Division

> Talis Systems Ltdhttp://www.talis.com

>
> --
> ----
> n-squared : Talis Platform Developers
> Mailing List :http://groups.google.com/group/n2-dev
> Wiki :http://n2.talis.com