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Dominic Tarr committed on 10/3/2016, 11:24:03 AM

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LICENSEadded
README.mdadded
index.jsadded
package.jsonadded
test/index.jsadded
LICENSEView
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1 …+Copyright (c) 2016 'Dominic Tarr'
2 …+
3 …+Permission is hereby granted, free of charge,
4 …+to any person obtaining a copy of this software and
5 …+associated documentation files (the "Software"), to
6 …+deal in the Software without restriction, including
7 …+without limitation the rights to use, copy, modify,
8 …+merge, publish, distribute, sublicense, and/or sell
9 …+copies of the Software, and to permit persons to whom
10 …+the Software is furnished to do so,
11 …+subject to the following conditions:
12 …+
13 …+The above copyright notice and this permission notice
14 …+shall be included in all copies or substantial portions of the Software.
15 …+
16 …+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
17 …+EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
18 …+OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
19 …+IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR
20 …+ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
21 …+TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
22 …+SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
README.mdView
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1 …+# status-swarm
2 …+
3 …+A very simple (secure) replication protocol.
4 …+
5 …+`status-swarm` replicates a single value per node,
6 …+where the node's public key is the id, and the value
7 …+may be updated, but new values always win.
8 …+`status-swarm` is intended for relatively long lived connections.
9 …+
10 …+When reconnecting to a node, overhead is small,
11 …+you only send the last time stamp from that peer.
12 …+
13 …+However, you may receive the same message multiple times if connected to
14 …+more than one peer, and upon connecting to a new peer for the first time,
15 …+you may re-receive messages you have already seen.
16 …+
17 …+``` js
18 …+
19 …+
20 …+```
21 …+
22 …+
23 …+## API
24 …+
25 …+### swarm = Swarm(keys)
26 …+
27 …+create a new instance with a given ssb-keys keypair.
28 …+
29 …+### swarm.update(value)
30 …+
31 …+update your status. the value will be wrapped and signed:
32 …+
33 …+``` js
34 …+{
35 …+ id: <your_id>,
36 …+ ts: <localtimestamp>,
37 …+ data: <value>,
38 …+ signature: <sig>
39 …+}
40 …+```
41 …+
42 …+### swarm.get(id)
43 …+
44 …+return the current value for this `id` (or `undefined`)
45 …+
46 …+### swarm.last(id)
47 …+
48 …+get the timestamp that you last received something from a given node.
49 …+This is _their_ local time, which may be skewed from yours,
50 …+but you need to know their time, because you will use this to
51 …+request they have received since this time.
52 …+
53 …+### swarm.send(since), swarm.recv(id)
54 …+
55 …+Set up replication between two peers. note that it's _not_ implemented as a duplex stream,
56 …+but as a separate source and a sink. This method makes for a more symmetrical protocol.
57 …+on connecting, each peer requests the remote's `swarm.send(ts||0)` over [rpc](https://github.com/ssbc/muxrpc)
58 …+
59 …+`send` can be exposed over muxrpc, but `recv` can be a private api.
60 …+your code might look something like this:
61 …+
62 …+``` js
63 …+//this code should exist on both ends.
64 …+sbot.on('rpc:connect', function (rpc) {
65 …+ var id = rpc.id
66 …+ pull(rpc.send(swarm.last(id)), swarm.recv(id))
67 …+})
68 …+
69 …+//advertise your network location, for example.
70 …+rpc.update({host: HOST, port: PORT})
71 …+```
72 …+
73 …+## TODO
74 …+
75 …+To stop the replication data growing too large, implement filtering (say, filter ids you don't care about)
76 …+expire messages that are too old (say, to represent only peers that are online, say within the last few hours)
77 …+
78 …+## License
79 …+
80 …+MIT
81 …+
index.jsView
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1 …+var pull = require('pull-stream')
2 …+var Notify = require('pull-notify')
3 …+var ssbKeys = require('ssb-keys')
4 …+var Cat = require('pull-cat')
5 …+var timestamp = require('monotonic-timestamp')
6 …+
7 …+module.exports = function (keys) {
8 …+
9 …+ var notify = Notify()
10 …+ var data = {} //key->value
11 …+ var local = {} //our local time we received a given message.
12 …+ var remote = {} //each remote's localtime
13 …+ var listeners = []
14 …+
15 …+ function broadcast(val, localtime) {
16 …+ notify(val)
17 …+ notify(localtime)
18 …+ listeners.forEach(function (l) {
19 …+ l(val, localtime)
20 …+ })
21 …+ }
22 …+
23 …+ function _update (value, id) {
24 …+ if('number' === typeof value) {
25 …+ remote[id] = Math.max(remote[id] || 0, value)
26 …+ return
27 …+ }
28 …+
29 …+ if(data[value.id]) {
30 …+ if(data[value.id].ts >= value.ts) return 'seen'//no change
31 …+ }
32 …+
33 …+ if(!ssbKeys.verifyObj({public: value.id}, value))
34 …+ return 'invalid' //signature invalid
35 …+
36 …+ data[value.id] = value
37 …+ var ts = local[value.id] = timestamp()
38 …+
39 …+ broadcast(value, ts)
40 …+ }
41 …+
42 …+ return {
43 …+ get: function (id) {
44 …+ return data[id]
45 …+ },
46 …+ last: function (id) {
47 …+ return (id === keys.id ? local[id] : remote[id]) || 0
48 …+ },
49 …+ update: function (value) {
50 …+ var localtime = timestamp()
51 …+ var val = data[keys.id] = ssbKeys.signObj(keys, {
52 …+ id: keys.id,
53 …+ //statuses for same id with smaller timestamps are ignored.
54 …+ ts: localtime,
55 …+ data: value
56 …+ })
57 …+ //special case, for us
58 …+ local[keys.id] = localtime
59 …+ broadcast(val, localtime)
60 …+ return val
61 …+ },
62 …+ send: function (since) {
63 …+ var d = []
64 …+ for(var k in data) if(local[k] > since) d.push(data[k])
65 …+ if(d.length)
66 …+ d.push(timestamp()) //also send the localtime.
67 …+ return Cat([pull.values(d), notify.listen()])
68 …+ },
69 …+ recv: function (id) {
70 …+ return pull.drain(function (value) {
71 …+ _update(value, id)
72 …+ })
73 …+ },
74 …+ changes: function (onChange) {
75 …+ listeners.push(onChange)
76 …+ return function () {
77 …+ var i = listeners.indexOf(onChange)
78 …+ if(~i) listeners.splice(i, 1)
79 …+ }
80 …+ }
81 …+ }
82 …+}
83 …+
84 …+
package.jsonView
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1 …+{
2 …+ "name": "status-swarm",
3 …+ "description": "",
4 …+ "version": "0.0.0",
5 …+ "homepage": "https://github.com/dominictarr/status-swarm",
6 …+ "repository": {
7 …+ "type": "git",
8 …+ "url": "git://github.com/dominictarr/status-swarm.git"
9 …+ },
10 …+ "dependencies": {
11 …+ "monotonic-timestamp": "0.0.9",
12 …+ "pull-cat": "^1.1.11",
13 …+ "pull-notify": "^0.1.1",
14 …+ "pull-stream": "^3.4.5",
15 …+ "ssb-keys": "^6.1.2"
16 …+ },
17 …+ "devDependencies": {
18 …+ "tape": "^4.6.0"
19 …+ },
20 …+ "scripts": {
21 …+ "test": "set -e; for t in test/*.js; do node $t; done"
22 …+ },
23 …+ "author": "'Dominic Tarr' <dominic.tarr@gmail.com> (dominictarr.com)",
24 …+ "license": "MIT"
25 …+}
test/index.jsView
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1 …+var pull = require('pull-stream')
2 …+
3 …+var Swarm = require('../')
4 …+var ssbKeys = require('ssb-keys')
5 …+
6 …+var tape = require('tape')
7 …+
8 …+var ak = ssbKeys.generate()
9 …+var bk = ssbKeys.generate()
10 …+var ck = ssbKeys.generate()
11 …+var alice = Swarm(ak)
12 …+var bob = Swarm(bk)
13 …+var carol = Swarm(bk)
14 …+
15 …+//because everything in this module is sync,
16 …+//testing is quite straightforward.
17 …+
18 …+tape('simple', function (t) {
19 …+
20 …+ var start = Date.now()
21 …+
22 …+ alice.update({foo: true, address: 'here'})
23 …+
24 …+ bob.update({bar: true, address: 'there'})
25 …+
26 …+ console.log(alice.get(ak.id))
27 …+
28 …+ var ary = []
29 …+ pull(alice.send(0), pull.drain(function (data) {
30 …+ ary.push(data)
31 …+ }))
32 …+
33 …+ var ts = ary.pop()
34 …+ t.deepEqual(ary, [alice.get(ak.id)])
35 …+ t.ok(ts >= start)
36 …+ t.end()
37 …+
38 …+})
39 …+
40 …+tape('replicate', function (t) {
41 …+
42 …+
43 …+ pull(bob.send(0), alice.recv(bk.id))
44 …+
45 …+ t.deepEqual(alice.get(bk.id), bob.get(bk.id))
46 …+
47 …+ bob.update({bar: false, address: 'yonder'})
48 …+
49 …+ t.deepEqual(alice.get(bk.id), bob.get(bk.id))
50 …+
51 …+ t.equal(alice.last(bk.id), bob.last(bk.id))
52 …+
53 …+ //connect bob -> alice -> carol
54 …+ pull(alice.send(Date.now()), carol.recv(bk.id))
55 …+
56 …+ t.deepEqual(carol.get(bk.id), undefined)
57 …+
58 …+ bob.update({bar: 1, address: 'thar'})
59 …+
60 …+ t.deepEqual(carol.get(bk.id), bob.get(bk.id))
61 …+ t.deepEqual(alice.get(bk.id), bob.get(bk.id))
62 …+
63 …+
64 …+ t.end()
65 …+
66 …+})
67 …+

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