Create Browser gateway

[vasco-santos]

More information will be availble from the OKRs

[linonetwo]

I've implemented a naive one https://github.com/linonetwo/ipfs-browser-gateway, but I'm not familiar with ipfs' DAG traversal, so I stopped there.

Can you give me some advice, so I can make PR here?

[daviddias]

@linonetwo that's super cool! What we want is to mimic the IPFS HTTP Gateway that one gets when spawning a daemon but through a service worker http proxy.

Why did you need DAG Traversal? The HTTP Gateway only operates over Files. Could you give me an example?

[linonetwo]

Besides adding a single file, people would serve the website and add folders too.
For example, https://ipfs.io/ipfs/QmeYxwj4CwCeGVhwi3xLrmBZUUFQdftshSiGLrTdTnWEVV is a folder. I thought they were added by ipfs-unixfs, thus properly reading them needs traversal of DAG.

When I node.files.get this hash, I got an array of object that has depth, but I was not clear whether this is related to DAG.
https://github.com/linonetwo/ipfs-browser-gateway/blob/master/public/serviceWorker.js#L67-L76

https://ipfs.io/ipfs/QmRoYXgYMfcP7YQR4sCuSeJy9afgA5XDJ78JzWntpRhmcu seems to be another kind of folder. And use node.files.get on it will get huge data. ipfs.io gateway seems to deal with these two kinds of folders differently.

@diasdavid Maybe I need to read the code in the ipfs daemon?

[daviddias]

@linonetwo check the http gateway code at https://github.com/ipfs/js-ipfs/tree/master/src/http/gateway

[linonetwo]

Thanks, I know how it works now.

I can reuse /src/http/gateway/resolver.js and copy some core parts of /src/http/gateway/resources/gateway.js if ipfs/src/http/gateway/resolver is exported and browserifyed.

But I didn't find a way to properly import ipfs/http/gateway/resolver.js into service worker now, so I have just copied them.

Most depended npm package was replaced by importScripts( CDN URL ). But some of them use exports internally, so I import them in following ways:

1. some packages can use this hack to import, but packages with const xxx = require can't
2. I use https://wzrd.in/standalone/xxxpackage to browserify const xxx = require on the fly, this may be slow since it's not a professional CDN

And I'm still learning how to return a stream from service worker, so still WIP.

[linonetwo]

It's mostly finished, but:

1. loading dependencies by importScripts synchronously is slow (10s)
2. it's not returning a Response, there is a bug, but I'm too sleepy to figure out, it's too late

Hope somebody can review it, it's mostly the same as https://github.com/ipfs/js-ipfs/tree/master/src/http/gateway

[vasco-santos]

@linonetwo I have already been working on this issue, so thanks for your contribution. I will analyse your implementation asap

[daviddias]

Repo for the service-worker-gateway project.

[linonetwo]

@vasco-santos Thank you too. I'm eager to discuss with you.