NB: This is an out of date zome, please see the holochain-open-dev/file-storage repo

file-storage-zome

A zome that can be mixed in to any DNA to provide basic file storage capabilities.

This aims to be a community maintained project and will receive support but minimal contributions from the dev team

Requirements

There are several considerations for an efficient implementation of file/blob storage:

• There is a limit of 4GB of WASM memory that can be used at any time
• Files must be chunked to provide uniform data distribution in the DHT
• There must be a way to validate that the file you receive is as expected

Specification

Files should be chunked outside the zome itself. A javascript reference implementation should be included in this repo which performs the chunking and restructuring operations

A manifest should describe a single file and how to retrieve all of the chunks. The hash of the manifest therefore becomes the address for retrieving the file. The manifest must contain:

• An ordered list of the hashes/addresses of the chunks
• Any additional metadata (e.g. description, file type etc)

validation logic must ensure that a manifest can only be stored in the DHT once all of the chunks are also stored

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The zome should expose the following interface:

• store_chunk(data: RawString) -> ZomeApiResult<Address>
• store_manifest(manifest: Manifest) -> ZomeApiResult<Address>
• get_chunk(address: Address) -> ZomeApiResult<RawString>
• get_manifest(address: Address) -> ZomeApiResult<Manifest>

The javascript interface should expose higher level functions to the end user such as :

• storeFile(bytes: UInt8Array): string | Error - returns the address of the manifest as a string
• getFile(address: string): UInt8Array | Error - given the manifest address returns the restructured chunks

Contributing

We follow the "fork-and-pull" Git workflow.

Fork the repo on GitHub
Clone the project to your own machine
Commit changes to your own branch
Push your work back up to your fork
Submit a Pull request so that we can review your changes

NOTE: Be sure to merge the latest from "upstream" before making a pull request