ByteRange API for the BlobStore

Context

Nuxeo BlobStore allow to access a stream but only as a whole object: there is no exposed API to access to a range of the stream.

Several use cases may require such an API:

• media playback
  • we support range inside the http download request, but still need to fetch tha full stream from the BlobStore backend.
• AFP preview
  • a common use case is to preview a few pages inside a large AFP stream that can be several GB

Most backend technically support byte range access:

• Filesystem obviously supports it
• S3 API supports a setRange API
• Azure has also a range attribute in their get-blob API
• GCP Storage also has a concept of range

Prototype

A prototype was created in order to validate that it can work with AFP 2 PDF conversion: nuxeo-core-binarymanager-byterange:

• expose a High level service to access byterange in a Blob
• storage adapter for each BlobStore
• S3 and FS implementation of the storage adapter

The current code was just a POC to validate the concepts:

• we probably want this to be part of the the BlobStore API at least on master
• I suspect we want to remove usage of BinaryManager

Design questions

• Make the Range API a first class citizen of BlobStore vs having a dedicated interface ?
• How do we make that new API available on 10.10