Synchronization protocol for multi-premises hosting of digital content items

One or more non-transitory computer-readable media storing instructions which, when executed by one or more processors, cause the one or more processors to perform functions comprising:

• receiving a first commit request from a computing device, the first commit request including a first set of one or more identifiers of one or more first content item blocks, the one or more first content item blocks making up a content item stored at the computing device;
• based at least in part on the first commit request, determining a second set of one or more identifiers that includes one or more identifiers of the first set of one or more identifiers not yet stored at a content item block server;
• sending, to the computing device, the second set of one or more identifiers;
• receiving a second commit request from the computing device, the second commit request including the first set of one or more identifiers of the one or more first content item blocks, and an identifier of the content item block server;
• based at least in part on the second commit request, determining that no content item block from the one or more first content item blocks is missing at the content item block server;
• based at least in part on determining that no content item block from the one or more first content item blocks is missing at the content item block server, committing the content item to the content item block server.

A system, comprising:

• one or more processors configured to execute instructions to perform functions comprising:
• receiving a first commit request from a computing device, the first commit request including a first set of one or more identifiers of one or more first content item blocks, the one or more first content item blocks making up a content item stored at the computing device;
• based at least in part on the first commit request, determining a second set of one or more identifiers that includes one or more identifiers of the first set of one or more identifiers not yet stored at a content item block server;
• sending, to the computing device, the second set of one or more identifiers;
• receiving a second commit request from the computing device, the second commit request including the first set of one or more identifiers of the one or more first content item blocks, and an identifier of the content item block server;
• based at least in part on the second commit request, determining that no content item block from the one or more first content item blocks is missing at the content item block server;
• based at least in part on determining that no content item block from the one or more first content item blocks is missing at the content item block server, committing the content item to the content item block server.