tahoe-lafs/roadmap.txt

['*' means complete]

Connection Management:
*v1: foolscap, no relay, live=connected-to-queen, broadcast updates, full mesh
 v2: live != connected-to-queen, connect on demand
 v3: relay?

File Encoding:
*v1: single-segment, no merkle trees
*v2: multiple-segment (LFE)
 v3: merkle tree to verify each share
 v4: merkle tree to verify each segment

Share Encoding:
*v1: fake it (replication)
*v2: PyRS
*v2.5: ICodec-based codecs, but still using replication
*v3: C-based Reed-Solomon

URI:
*v1: really big
 v2: derive more information from version and filesize, to remove codec_name,
     codec_params, tail_codec_params, needed_shares, total_shares, segment_size

Upload Peer Selection:
*v1: permuted peer list, consistent hash
*v2: permute peers by verifierid and arrange around ring, intermixed with
     shareids on the same range, each share goes to the
     next-clockwise-available peer
 v3: reliability/goodness-point counting?
 v4: denver airport (chord)?

Download Peer Selection:
*v1: ask all peers
 v2: permute peers and shareids as in upload, ask next-clockwise peers first
     (the "A" list), if necessary ask the ones after them, etc.
 v3: denver airport?

Filetable Maintenance:
*v1: queen-based tree of MutableDirectoryNodes, persisted to queen's disk
     no accounts
 v2: move tree to client side, serialize to a file, upload,
     queen.set_filetable_uri (still no accounts, just one global tree)
 v3: break world up into accounts, separate mutable spaces. Maybe
     implement SSKs
 v4: filetree

Checker/Repairer:
*v1: none
 v2: centralized checker, repair agent
 v3: nodes also check their own files

Storage:
*v1: no deletion, one directory per verifierid, one owner per share,
     leases never expire
*v2: multiple shares per verifierid [zooko]
 v3: deletion
 v4: leases expire, delete expired data on demand, multiple owners per share

UI:
*v1: readonly webish (nevow, URLs are filepaths)
*v2: read/write webish, mkdir, del (files)
 v2.5: del (directories)
 v3: PB+CLI tool.
 v3.5: XUIL?
 v4: FUSE

Operations/Deployment:
 v1: doc how to set up a network (introducer, vdrive server, nodes)
 v2: Windows port and testing
 v3: Trac instance

back pocket ideas:
 when nodes are unable to reach storage servers, make a note of it, inform
 queen eventually. queen then puts server under observation or otherwise
 looks for differences between their self-reported availability and the
 experiences of others

 store filetable URI in the first 10 peers that appear after your own nodeid
 each entry has a sequence number, maybe a timestamp
 on recovery, find the newest

 multiple categories of leases:
  1: committed leases -- we will not delete these in any case, but will instead
     tell an uploader that we are full
   1a: active leases
   1b: in-progress leases (partially filled, not closed, pb connection is
       currently open)
  2: uncommitted leases -- we will delete these in order to make room for new
     lease requests
   2a: interrupted leases (partially filled, not closed, pb connection is
       currently not open, but they might come back)
   2b: expired leases

  (I'm not sure about the precedence of these last two. Probably deleting
  expired leases instead of deleting interrupted leases would be okay.)

big questions:
 convergence?
 peer list maintenance: lots of entries