delta-stream

Emit deltas in change over a stream

Data protocol

[key, value, sourceIdentifier, timestamp]

A delta-stream emits an array, where the first value is the key that has changed and the second value is the new value. This represents the delta in change on the object.

The third value is a source identifier. It's used to identify who created this delta

The fourth value is a time stamp which can be used for clever synchronization.

Example

Create deltas that handle changes in state. Then create stream reprensentations of deltas

var Delta = require("delta-stream")

var delta1 = Delta()
    , delta2 = Delta()

var stream1 = delta1.createStream()
    , stream2 = delta2.createStream()

delta1.on("change:delta1", function (value) {
    console.log("[CHANGE:DELTA1]", value)
})

delta2.on("change:delta2", function (value) {
    console.log("[CHANGE:DELTA2]", value)
})

stream1.pipe(stream2).pipe(stream1)

delta1.set("delta2", "hello")
delta2.set("delta1", "world")

Almost Compatible modules [NEED TO BE REFACTORED]

• text-node
• arrow-keys
• attribute
• form-stream

Docs

delta.set

delta.set sets a key value pair on a delta

var delta = Delta()

delta.set("foo", "bar")

assert.equal(delta.get("foo"), "bar")

If you set a value to undefined it will be deleted from the internal state object.

delta.get

delta.get get's a value by it's key

var delta = Delta()

delta.set("foo", "bar")

assert.equal(delta.get("foo"), "bar")

delta.has

delta.has returns true or false based on whether the the key is set

var delta = Delta()

assert.equal(delta.has("foo"), false)

delta.delete

delta.delete deletes the value attached to a key. Internally this is the same as setting a value to undefined.

var delta = Delta()

delta.set("foo", "bar")
delta.delete("foo")

assert.equal(delta.has("foo"), false)

delta.toJSON

Returns the entire internal state as an object

delta.createStream

Create a scuttlebutt stream of the delta. See scuttlebutt

Installation

npm install delta-stream

Contributors

• Raynos

MIT Licenced