Briefcases

Briefcases are local copies of iModel that users can acquire to work with the iModel. Users can make changes to their copy of iModel and then push them as a single Changeset file into iModelHub.

Changesets

Briefcases synchronize their changes through changesets. Changesets form a linear timeline of iModel changes. To do this, changesets have to be in a strict order and must be based on a single parent changeSet.

ChangesetId

A ChangesetId is a 40 value that is used to validate changesets. A ChangesetId is generated from the ChangesetId of its parent as well as a hash of its contents. Since ChangesetIds are essentially random strings of numbers, they are not useful for determining changeset sequences.

ChangesetIndex

Once a changeset is pushed to iModelHub it is stored on a timeline

BriefcaseId

Each Briefcase has a unique 24 bit integer id. BriefcaseId is stored in a briefcase file after download, and is used to identify where changes have occurred.

• Every ElementId contains the BriefcaseId from which it was created.
• Every Changeset has the BriefcaseId of the Briefcase that pushed it.
• Locks are associated with BriefcaseIds on the server.

Since BriefcaseIds are limited, it is recommended to reuse briefcases instead of acquiring new ones. There are limits how many Briefcases a single user can acquire per minute/total to prevent users accidentally acquiring too many Briefcases.

Working with briefcases

To work with Briefcases, BriefcaseDb methods should be used instead of calling iModelHub API directly:

• Acquiring and opening a briefcase
• Pulling changes
• Creating and pushing changes