[gcs-pcs-list] (possible) issue: what to do for redirects?

[Daniel Chudnov]

I'm not sure if this is an unAPI issue or not.

In OPA, requests for things like images in binary formats can be
simply redirected to another site.  See the flickr links here for
examples:

  http://onebiglibrary.net/project/opa/opa-0.2-release-with-json-wrapper

If you follow, for example, the flickr jpeg_Original format link, OPA
will respond with 302 Found with the flickr URL in the Location: header,
and clients (browsers, wget) will follow the Location header URL.  e.g.:

    [dlc33 at sildin tmp]$ wget "http://opa.onebiglibrary.net/?uri=http://flickr.com/photos/dchud/100544935/&format=jpeg_Original"
    --12:30:45--  http://opa.onebiglibrary.net/?uri=http://flickr.com/photos/dchud/100544935/&format=jpeg_Original
               => `index.html?uri=http:%2F%2Fflickr.com%2Fphotos%2Fdchud%2F100544935%2F&format=jpeg_Original'
    Resolving opa.onebiglibrary.net... 207.210.245.105
    Connecting to opa.onebiglibrary.net|207.210.245.105|:80... connected.
    HTTP request sent, awaiting response... 302 Found
    Location: http://static.flickr.com/32/100544935_ac537ae9e5_o.jpg [following]
    --12:30:50--  http://static.flickr.com/32/100544935_ac537ae9e5_o.jpg
               => `100544935_ac537ae9e5_o.jpg'
    Resolving static.flickr.com... 68.142.213.135
    Connecting to static.flickr.com|68.142.213.135|:80... connected.
    HTTP request sent, awaiting response... 200 OK
    Length: 1,357,967 (1.3M) [image/jpeg]

    100%[====================================>] 1,357,967    453.28K/s

    12:30:53 (451.83 KB/s) - `100544935_ac537ae9e5_o.jpg' saved [1357967/1357967]

    [dlc33 at sildin tmp]$ file 100544935_ac537ae9e5_o.jpg
    100544935_ac537ae9e5_o.jpg: JPEG image data, EXIF standard 2.2


At first, OPA was returning 301 Moved Permanently but that didn't
seem right as it hadn't "moved" at all.  302 Found seemed better.

Admittedly, OPA is a weird application, seeing as it's a proxy, but
it still raises the questions:

 - Is the redirection response within the scope of unAPI?
   - If so, should we standardize the suggested HTTP status code(s)?
     - If so, is 302 Found correct?

 - Is it wrong for OPA to use a redirect here?  i.e. would it be more
   appropriate for OPA (as an unAPI service) to fetch the remote data
   itself, and return *that* to the user directly, with the correct
   content-type and a 200 code?

This one is hurting my brain, I have no idea what the answers are.

  -Dan


-- 
Daniel Chudnov
Yale Center for Medical Informatics
(203) 737-5789