develop an image manager service that works with GeoServer

[tschaub]

So, AtomPub is an attractive option for managing images in GeoServer. However, browsers can't implement the proposed multipart media creation  proposal for AtomPub (for multipart data, we are stuck with multipart/form-data and cannot set headers when posting data from the client filesystem).

So, we can use regular old multipart/form-data for creating new resources (posting a file from the client filesystem). The design proposal suggests that a url can be submitted to create a new resource. We could do Atom here, but it seems silly to mix content types. So, we agree on parameter names and use form-encoding (unless someone else has a different proposal).

In terms of getting information about image resources, Atom would make a good transport format. Of course JSON will always be easier to handle when the client is a browser.

Anyway, interaction would look something like this:

Request

GET /geoserver/images/

Response (in whatever content type, json below)

{
    images: [
        {
            id: "1",
            title: "Railroad Station",
            categories: ["transportation"],
            links: [
                {
                    rel: "self",
                    type: "image/png",
                    href: "http://example.org/geoserver/images/1.png"
                }, {
                    rel: "alternate",
                    type: "application/json",
                    href: "http://example.org/geoserver/images/1.json"
                }
            ]
        }
    ]
}

If the client posts an image from their filesystem, the request might look like the following:

POST /geoserver/images/
Content-Type: multipart/form-data; boundary=AaB03x

--AaB03x
Content-Disposition: form-data; name="title"

Major City
--AaB03x
Content-Disposition: form-data; name="categories"

political
--AaB03x
Content-Disposition: form-data; name="categories"

demographic
--AaB03x
Content-Disposition: form-data; name="image"; filename="big_city.png"
Content-Type: image/png
Content-Transfer-Encoding: binary

... contents of big_city.png ...
--AaB03x--

And the response would be a 201 with some representation of the new resource (perhaps like the json above).

The design documents show the user being able to create a new resource by submitting a url for an image already online. I'd suggest that this is not completely necessary. If implemented, it would keep things simpler to have GeoServer fetch the image and store a copy - so we don't have to deal with two image types (local and remote) when requesting a list of resources. If not implemented, then the user downloads the image first before posting.