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wishlist: metalink (automating file verification, queues)
1/22/2008 12:56:26 PM
by twanj
I'd like to see metalink support. It's a simple XML file that can be used to add a bunch of files to a download queue. You can list multiple mirrors for each file too. It can also include MD5, SHA-1, & other checksums, so if you can support that you can verify that a file downloaded correctly. You can also include chunk checksums for large files, which allow downloads to be repaired. About 30 apps from download managers to FTP & P2P clients, and web browsers support it.

Here's an example of what a single file metalink looks like. 
 
   
     
     
       example-md5-hash
       example-sha1-hash
     
     
       ftp://ftp.example.com/example.ext
       ftp://ftp.example.net/example.ext
       http://example.com/example.ext 
       http://example.net/example.ext

1/22/2008 3:48:28 PM
by ALTools
Hello,

I've just added that to the ALFTP Wish List and will send this to the ALFTP PM.

From the quick look that I had at Metalink, it looks very good. Of course we'll need to have a deeper look into it, but it doesn't sound like supporting it would be very difficult. (XML is drop dead simple to work with.)

I'm also going to take this over to the ALToolbar PM as well. That's a more natural place for us to start for Metalink. (We're releasing ALToolbar very shortly, so check back and you'll see what I mean there then.)

Regards,

Ryan
1/22/2008 6:15:53 PM
by twanj
Sounds good!

Having a client & server you could do some interesting things. Some P2P apps use metalinks to share their library with other users. For instance, say you have a set of files your friend wants. You select them, create a metalink, & post it somewhere or email it. The metalink contains links to all the files you're sharing, but also checksum info so the files can be downloaded from other users as well.

You could also create a metalink for uploading, then if there was an error in the upload you could just retransfer the error portion (determined from chunk checksums) instead of the whole file. That'd be really nice for large files like ISOs.

The XML didn't come out, but you can see how simple it is on the wikipedia page.