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

Getting Started

Clone the repo (Or better still, fork then clone, so you can work on it too)

To run the holochain portion

cd dna-src
hc run --package

To run the frontend

Open a new separate terminal (So the backend stays running in the other one)

Install the http-server utility npm install -g http-server (or use another lightweight http-server)

Then

cd ui
http-server

Open your web browser and upload and download some files

Current Status

File storage zome - There is currently scaffolding. It needs coding, validation and testing Client library - There is a es6 module that returns mocked data. Sample UI - This is running and using the lib. Application holochain data (where the list of files is storage) is currently mocked in the frontend.

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