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The Blockstore proposals are fairly long, so this doc tries to summarize some of the principle differences.

Collections

• All proposals center ownership, permissions, and licensing around the concept of a Collection.
• Each piece of content belongs to exactly one Collection.
• Examples:
  • single course (possibly multiple runs)
  • problem bank
  • library of videos created by a video team

Differences: Collection Versioning

Original and Database Proposals

• Collections point to versioned content, and are also versioned as a whole.

File Proposal

• Collections point to versioned content, but the Collection itself is not versioned.

Content Primitives

• Identified by UUID.
• Versioned numerically (1, 2, 3, etc.)
• Tagging metadata is stored outside of the core Blockstore.

Content Primitives

• Identified by UUID.
• Versioned numerically (1, 2, 3, etc.)
• Tagging metadata is stored outside of the core Blockstore.

Differences: Granularity and Versioning

Original Proposal and Database Proposal

• Files/Assets are tracked individually.
• Units are tracked individually.

Original Proposal

• In addition to per-Unit and per-File tracking, ContentSets (a group of Links) are also versioned.

File Proposal

• ContentBundles are versioned as a whole, not individual assets inside them.
• Depending on the intended usage, a ContentBundle could be a single video, a Unit, or an entire Sequence.

Differences: OLX vs. Assets

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• All content is stored in Content Bundles, which is like a small directory of files.
• The OLX for a Unit would go into an XML file in a ContentBundle.
• All Bundle content is stored in an S3-like object store.
• Metadata about what content constitutes a particular version is in the object store, not the database.
• Assets used by the Unit would go into the same ContentBundle.
• Advantages
  • Units are more self contained.
  • Easier to adapt for use cases outside of Open edX, since ContentBundles don't assume an OLX/Assets divide.
  • Easier to associate bundles of related Assets, like a Video's various encodings, subtitles, thumbnails, etc.
  • Cheaper storage.

Differences:

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Original Proposal and Database Proposal

• Files/Assets are tracked individually.
• Units are tracked individually.

Original Proposal

• In addition to per-Unit and per-File tracking, ContentSets (a group of Links) are also versioned.

File Proposal

• ContentBundles are versioned as a whole, not individual assets inside them.
• Depending on the intended usage, a ContentBundle could be a single video, a Unit, or an entire Sequence.

Differences: Modeling Sequences and Courses

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None of the proposals really addresses this, but all of them assume that there will be an external system (either a plugin or separate service) that uses ElasticSearch as a backend.

Collections

• All proposals center ownership, permissions, and licensing around the concept of a Collection.
• Each piece of content belongs to exactly one Collection.
• Examples:
  • single course (possibly multiple runs)
  • problem bank
  • library of videos created by a video team

Differences: Collection Versioning

Original and Database Proposals

• Collections point to versioned content, and are also versioned as a whole.

File Proposal

• Collections point to versioned content, but the Collection itself is not versioned.

Neither of these stances is fundamental to the designs.

Questions for Discussion

1. What are the use cases for Collection-level versioning?
   1. Licensing version ranges for the Collection.