Fission is working on defining a Fission File System spec (very work in progress in our whitepaper) that adds some convenience features on top of IPFS, along with support for our encrypted files implementation.
Here’s a neat trick that we came up with while working on metadata:
https://ipfs.runfission.com/ipfs/QmaxBR8djuHiQ5DcDH92rsVAjaeLFNnT8awcLKiGE5SiEx
If you follow that link, you should see this image loaded:
However, we’ve also attached a link within that IPFS entry (which is the same boris.fission.name directory that we use as our default example public content):
https://ipfs.runfission.com/ipfs/QmaxBR8djuHiQ5DcDH92rsVAjaeLFNnT8awcLKiGE5SiEx/embedded
How does this work? CIDs for images are actually DAG Nodes pointing to a bunch of chunks of data that make up the image. We put an extra link in there to point to more data:
{
"data":"CAIY65c8IICAECCAgBAggIAQIOuXDA==",
"links": [
{"Cid":{"/":"QmYDARDj3A4sTVMkSC8wf7KjXo6MhzwLwHvoHnKzKVTAP6"},"Name":"","Size":262158},
{"Cid":{"/":"QmeG8Rw9YEZx8zw93wTyC5NgRemjufaT9HaWQvvp27cThf"},"Name":"","Size":262158},
{"Cid":{"/":"QmdrQ5FNZN6DbMuC7yMnH5iWpk667eW99sHEQWFkzVHTXz"},"Name":"","Size":262158},
{"Cid":{"/":"QmS51h7vQPvRxH1hQjMKhREXX22DaqgYPNZAi3jJvVqXL5"},"Name":"","Size":199673},
{"Cid":{"/":"QmWKst5WVNTPfMsSFCQEJYBJLEsUZfghqrKXJBVU4EuA76"},"Name":"embedded","Size":1234}
]
}
The image still loads fine. This is a technique we’re looking at to store metadata alongside files broadly – with some specific interesting things to be done with images, like storing multiple different sizes along with the original image.
Problem 1: Doesn’t work for files smaller than the chunk size (32K)
Say we have very short content, like hello world, which by itself looks like this:
https://ipfs.runfission.com/ipfs/QmT78zSuBmuS4z925WZfrqQ1qHaJ56DQaTfyMUF7F8ff5o
And then add the same /embedded link:
{
"data":"CAISDGhlbGxvIHdvcmxkChgM",
"links":
[
{"Cid":{"/":"QmWKst5WVNTPfMsSFCQEJYBJLEsUZfghqrKXJBVU4EuA76"},"Name":"embedded","Size":1234}
]
}
It doesn’t work / display correctly:
https://ipfs.runfission.com/ipfs/QmZMgruHmTJv6MQSvq5RZhrskfcKwFooqmDpet78jdQcst
The /embedded path does still work though:
https://ipfs.runfission.com/ipfs/QmZMgruHmTJv6MQSvq5RZhrskfcKwFooqmDpet78jdQcst/embedded
Screenshot of that path:
IPFS / Gateway Issue
What we’ve identified is that if the IPFS gateway sees links in a node (what would otherwise be a single, non-chunked data node like a short piece of text or data), then it doesn’t interpret it as a content node.
Is this a bug? We think so, since it would be consistent to work in both cases.