└── readme.txt


/readme.txt:
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 1 | 
 2 |     What is scuttlebutt?
 3 | 
 4 | Status of this memo
 5 | 
 6 |   draft spec
 7 | 
 8 | Abstract
 9 | 
10 |   The goal of this document is to specify what it means to say you have
11 |   implemented "scuttlebutt". Because scuttlebutt is intended as an living,
12 |   changing protocol, this is necessarily in terms of other implementations.
13 |   That is, you have implemented scuttlebutt if you can communicate with other scuttlebutt
14 |   implementations.
15 | 
16 | Definition of terms
17 | 
18 |   1. Protocol Layer.
19 |     Signing format.
20 |     Transport format.
21 | 
22 |   2. Platform Layer.
23 |     Content format.
24 | 
25 |   3. Application Layer.
26 | 
27 | 
28 | Defining interoperability.
29 | 
30 |   To say that Alice and Bob both speak scuttlebutt, it MUST be true that
31 |   a message created in one implementation can be transferred to, validated,
32 |   and rendered (in the application layer of) another implementation. This MUST
33 |   apply in both directions.
34 | 
35 |   Although both implementations may store the message, it is not required
36 |   that their database formats be mutually intelligible.
37 | 
38 |   If we consider 3 implementations, the situation is more complicated.
39 |   If Carol implements a new transport format, and Bob also supports it,
40 |   Bob is doing scuttlebutt because he can mutually exchange messages with Alice,
41 |   who is defined as the source of scuttlebutt. If Carol supports the old format
42 |   but chooses to use the new transport format when communicating with bob, that is still
43 |   scuttlebutt. If Carol discontinues the old format, she can still receive Alice's
44 |   messages via Bob, so that is still scuttlebutt. If Bob also discontinues the old format,
45 |   then they have broken scuttlebutt because they cannot receive Alice's messages.
46 |   However if Alice also supports the new transport format, then scuttlebutt is still happening.
47 | 
48 |   If Carol introduces a new signing format there is a greater risk of breaking scuttlebutt.
49 |   For that signing format to be considered scuttlebutt, it must be accepted by other
50 |   scuttlebutt peers. As long as there is one format that all peers can mutually produce
51 |   and consume, then scuttlebutt is still happening.
52 | 
53 |   A particular format may be consumed but not produced by other peers. It's not required
54 |   that Alice and Bob can both produce the same type of messages, just that Alice and Bob
55 |   can consume each other's messages.
56 | 
57 |   There is also the possibility of transports that can only move old messages, such as by
58 |   the message hash. Of course, there needs to exist some other transport that can move new messages.
59 |   The main transport protocol does this by requesting new messages signed by a particular public key.
60 |   If Bob supports the new signing format, he can create new format messages that reference
61 |   old format messages, from Alice. And then Carol can request Alice's old-format messages by hash
62 |   references in Bob's messages. If Alice upgrades to the new signing format and stops producing
63 |   old format messages, then it's still scuttlebutt even if the peers no longer have the ability
64 |   to replicate or produce new old-format messages. As long as there is some way to still aquire
65 |   and understand the old messages.
66 | 
67 |   For example, due to many quirks in the old format, it's not desirable to force new implementors
68 |   to implement it. But to minimally support it, they may transport it in a few format, store
69 |   it in a new format, and convert it into the old format for signing and hashing. The new format
70 |   must just retain sufficient context for it to be possible to convert to the old signing format.
71 | 
72 |   Alice and Bob's scuttlebutt implementations must be sufficiently compatibile, but
73 |   this does not mean they need to be identicle. Alice may store her messages in a different
74 |   database format to Bob. Database formats MAY be mutually intelligible, but it is not required.
75 | 


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