Namespace Pollution Mechanism

    causaltrack

    0.4.1 • Public • Published

    CausalTrack

    Keywords: Causality tracking, version vectors, interval version vectors, version vector with exceptions

    This project provides structures for causality tracking. The first one is the well-known version vector (VV) which allows to characterise on-the-fly causality between events.

    The second one is the interval version vector (IVV) [1] which provides a tracking of semantically dependent events. Therefore, independent events are non-blocking to each other.

    The next one is a version vector with exceptions (VVwE) [2] which provides the same features than the IVV. Nevertheless, it does not use the same underlying structure.

    We provide another version of the VVwE called perishing version vector with exceptions (PVVwE) where exceptions disappear over time by design. Such vector is useful in practice since messages are expected to arrive within defined range of time. Also, the site identifiers that are not used anymore tend to disappear.

    Installation

    $ npm install causaltrack
    

    Usage

    The module has been browserified and uglified. To include CausalTrack within your browser, put the following line in your html:

    <script src="./causaltrack.bundle.js"></script>

    Then, whether you use the browserified version or nodejs:

    var VV = require('causaltrack').VV;   // version vector
    var IVV = require('causaltrack').IVV; // interval version vector
    var VVwE = require('causaltrack').VVwE; // version vector with exceptions
    var PVVwE = require('causaltrack').PVVwE; // perishing VVwE
     
    // #1 Initialize the causality tracking structure with the unique site
    // identifier 42
    var vv = new VV(42);
    var ivv = new IVV(42);
    var vvwe = new VVwE(42);
    var pvvwe = new PVVwE(42);
     
    // #2 Update the local entry of the local vector. Return a pair
    // {_e:entry, _c:counter} of the sender which uniquely identifies the operation
    var ecVV = vv.increment();
    var ecIVV = ivv.increment();
    var ecVVwE = vvwe.increment();
    var ecPVVwE = pvvwe.increment();
     
    // #3 Check if the operation has already been integrated
    vv.isLower(ecVV);
    ivv.isLower(ecIVV);
    vvwe.isLower(ecVVwE);
    pvvwe.isLower(ecPVVwE);
     
    // #4 Check if the operation is ready to be integrated
    vv.isRdy(rvv); // rvv instance of VV
    ivv.isRdy(ecIVV); // ecIVV the entry clock specifying a dependency to an o
    vvwe.isRdy(ecVVwE); // ecVVwE the entry clock specifying a dependency to an op
    pvvwe.isRdy(ecPVVwE);
     
    // #5 Increment the local vector with the entry clock of the received
    // operation supposedly ready
    vv.incrementFrom(ecVV);
    ivv.incrementFrom(ecIVV);
    vvwe.incrementFrom(ecVVwE);
    pvvwe.incrementFrom(ecPVVwE);

    References

    [1] Optimized OR-Sets without Ordering Constraints

    [2] Concise version vectors in WinFS

    Install

    npm i causaltrack

    DownloadsWeekly Downloads

    3

    Version

    0.4.1

    License

    MIT

    Last publish

    Collaborators

    • chat-wane