HttpSource ScriptLookupStrategy - multiple http sources in single Cantaloupe?

[stephenmcconnachie]

Hi everyone,

We are running an instance of Cantaloupe using HttpSource to fetch images from a restful API, but we have multiple APIs from different systems so I'm wondering if we might be able to target multiple HttpSource endpoints in a single Cantaloupe, or do we have to run multiple Cantaloupe instances, one per endpoint.

I had a look through the documentation for HttpSource https://cantaloupe-project.github.io/manual/5.0/sources.html#HttpSource and in particular the ScriptLookupStrategy. It seems that this method is used to lookup filepath / identifiers within a single HttpSource, but not to lookup which one of multiple http sources to use, based for example on identifier syntax.

So I don't think it is possible to have one Cantaloupe that targets multiple API endpoints, and routes the request via that ScriptLookupStrategy. But maybe I'm wrong?

All the best,
Stephen

[adolski]

"HttpSource" is the name of a component inside Cantaloupe. It doesn't refer to "an HTTP source." The same HttpSource can access any number of HTTP sources/servers. There are two ways to make that work:

1. Using BasicLookupStrategy, set HttpSource.BasicLookupStrategy.url_prefix to nothing and provide the encoded full source URL as the image identifier, for example: http://my-cantaloupe-server/iiif/2/http%3A%2F%2Fmy-images.org%2Fimage.jpg/info.json

2. Using ScriptLookupStrategy, analyze the identifier in the httpsource_resource_info() method of your delegates.rb file. It can return any URL including different hosts for different identifiers.

[stephenmcconnachie]

Thank you! I hadn't quite considered the idea of no prefix, so passing the full source URL - very neat solution for my use case - cheers.

[stephenmcconnachie]

I added a block in the delegates.rb to look for identifier substring and pass a fetch source conditionally. Works perfectly! What a great image server cantaloupe is. Thanks again.

[adolski]

Good to hear @stephenmcconnachie, thanks.