Yjs is a framework for optimistic concurrency control and automatic conflict resolution on arbitrary data types. The framework implements a new OT-like concurrency algorithm and provides similar functionality as [ShareJs] and [OpenCoweb]. Yjs was designed to take away the pain from concurrently editing complex data types like Text, Json, and XML. You can find some applications for this framework [here](https://dadamonad.github.io/yjs/examples/).
Yjs is a framework for optimistic concurrency control and automatic conflict resolution on shared data types. The framework implements a new OT-like concurrency algorithm and provides similar functionality as [ShareJs] and [OpenCoweb]. Yjs was designed to handle concurrent actions on arbitrary complex data types like Text, Json, and XML. We provide a tutorial and some applications for this framework on our [homepage](http://y-js.org/).
In the future, we want to enable users to implement their own collaborative types. Currently we provide data types for
* Text
* Json
* XML
You can create you own shared types easily. Therefore, you can take matters into your own hand by defining the meaning of the shared types and ensure that it is valid, while Yjs ensures data consistency (everyone will eventually end up with the same data). We already provide data types for
y-object | Add, update, and remove properties of an object. Circular references are supported. Included in Yjs
[y-list](https://github.com/y-js/y-list) | A shared linked list implementation. Circular references are supported
[y-selections](https://github.com/y-js/y-selections) | Manages selections on types that use linear structures (e.g. the y-list type). You can select a range of elements and assign meaning to them.
[y-xml](https://github.com/y-js/y-xml) | An implementation of the DOM. You can create a two way binding to Browser DOM objects
[y-text](https://github.com/y-js/y-text) | Collaborate on text. You can create a two way binding to textareas, input elements, or HTML elements (e.g. *h1*, or *p*)
[y-richtext](https://github.com/y-js/y-richtext) | Collaborate on rich text. You can create a two way binding to several editors
Unlike other frameworks, Yjs supports P2P message propagation and is not bound to a specific communication protocol. Therefore, Yjs is extremely scalable and can be used in a wide range of application scenarios.
We support several communication protocols as so called *Connectors*. You find a bunch of Connectors in the [y-connectors](https://github.com/rwth-acis/y-connectors) repository. Currently supported communication protocols:
* [XMPP-Connector](http://xmpp.org) - Propagates updates in a XMPP multi-user-chat room
* [WebRTC-Connector](http://peerjs.com/) - Propagate updates directly with WebRTC
* [IWC-Connector](http://dbis.rwth-aachen.de/cms/projects/the-xmpp-experience#interwidget-communication) - Inter-widget Communication
We support several communication protocols as so called *Connectors*. You can create your own connector too - read [this wiki page](https://github.com/y-js/yjs/wiki/Custom-Connectors). Currently, we support the following communication protocols:
You can use Yjs client-, and server- side. You can get it as via npm, and bower. We even provide a polymer element for Yjs!
[y-xmpp](https://github.com/y-js/y-xmpp) | Propagate updates in a XMPP multi-user-chat room ([XEP-0045](http://xmpp.org/extensions/xep-0045.html))
[y-webrtc](https://github.com/y-js/y-webrtc) | Propagate updates Browser2Browser via WebRTC
[y-test](https://github.com/y-js/y-test) | A Connector for testing purposes. It is designed to simulate delays that happen in worst case scenarios
The theoretical advantages over similar frameworks are support for
You can use Yjs client-, and server- side. You can get it as via npm, and bower. We even provide polymer elements for Yjs!
The advantages over similar frameworks are support for
* .. P2P message propagation and arbitrary communication protocols
* .. arbitrary complex data types
* .. offline editing: Only relevant changes are propagated on rejoin (unimplemented)
* .. AnyUndo: Undo *any* action that was executed in constant time (unimplemented)
* .. Intention Preservation: When working on Text, the intention of your changes are preserved. This is particularily important when working offline.
* .. offline editing: Changes are stored persistently and only relevant changes are propagated on rejoin
* .. AnyUndo: Undo *any* action that was executed in constant time (coming..)
* .. Intention Preservation: When working on Text, the intention of your changes are preserved. This is particularily important when working offline. Every type has a notion on how we define Intention Preservation on it.
## Use it!
You find a tutorial, examples, and documentation on the [website](https://dadamonad.github.io/yjs/).
You can find a tutorial, and examples on the [website](http://y-js.org). Furthermore, the [github wiki](https://github.com/y-js/yjs/wiki) offers more information about how you can use Yjs in your application.
Either clone this git repository, install it with [bower](http://bower.io/), or install it with [npm](https://www.npmjs.org/package/yjs).
### Bower
```
bower install rwth-acis/yjs
bower install y-js/yjs
```
Then you include the libraries directly from the installation folder.
```
@@ -51,28 +61,85 @@ And use it like this with *npm*:
Y = require("yjs");
```
## Status
Yjs is still in an early development phase. Don't expect that everything is working fine.
But I would become really motivated if you gave me some feedback :) ([github](https://github.com/rwth-acis/yjs/issues)).
# Y()
In order to create an instance of Y, you need to have a connection object (instance of a Connector). Then, you can create a shared data type like this:
```
var y = new Y(connector);
```
### Current Issues
* The History Buffer should be able to store operations in a database
* Documentation
* Reimplement support for XML as a data type
* Custom data types
## Support
Please report _any_ issues to the [Github issue page](https://github.com/rwth-acis/yjs/issues)!
I would appreciate if developers give me feedback on how _convenient_ the framework is, and if it is easy to use. Particularly the XML-support may not support every DOM-methods - if you encounter a method that does not cause any change on other peers, please state function name, and sample parameters. However, there are browser-specific features, that Y won't support.
# Y.Map
Yjs includes only one type by default - the Y.Map type. It mimics the behaviour of a javascript Object. You can create, update, and remove properies on the Y.Map type. Furthermore, you can observe changes on this type as you can observe changes on Javascript Objects with [Object.observe](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/observe) - an ECMAScript 7 proposal which is likely to become accepted by the committee. Until then, we have our own implementation.
##### Reference
* Create
```
var map = y.set("new_map", Y.Map).then(function(map){
map // is my map type
});
```
* Every instance of Y is an Y.Map
```
var y = new Y(options);
```
* .get(name)
* Retrieve the value of a property. If the value is a type, `.get(name)` returns a promise
* .set(name, value)
* Set/update a property. `value` may be a primitive type, or a custom type definition (e.g. `Y.Map`)
* .delete(name)
* Delete a property
* .observe(observer)
* The `observer` is called whenever something on this object changes. Throws *add*, *update*, and *delete* events
* .observePath(path, observer)
*`path` is an array of property names. `observer` is called when the property under `path` is set, deleted, or updated
* .unobserve(f)
* Delete an observer
# A note on intention preservation
When users create/update/delete the same property concurrently, only one change will prevail. Changes on different properties do not conflict with each other.
# A note on time complexities
* .get(name)
* O(1)
* .set(name, value)
* O(1)
* .delete(name)
* O(1)
* Apply a delete operation from another user
* O(1)
* Apply an update operation from another user (set/update a property)
* Yjs does not transform against operations that do not conflict with each other.
* An operation conflicts with another operation if it changes the same property.
* Overall worst case complexety: O(|conflicts|!)
# Status
Yjs is a work in progress. Different versions of the *y-* repositories may not work together. Just drop me a line if you run into troubles.
## Get help
There are some friendly people on [](https://gitter.im/y-js/yjs?utm_source=badge&utm_medium=badge&utm_campaign=pr-badge) who may help you with your problem, and answer your questions.
Please report _any_ issues to the [Github issue page](https://github.com/y-js/yjs/issues)! I try to fix them very soon, if possible.
## Changelog
##### 1.0
This is a complete rewrite of the 0.5 version of Yjs. Since Yjs 1.0 it is possible to work asynchronously on a persistent database, which enables offline support.
* Switched to semver versioning
* Requires a promise implementation in environment (es6 promises suffice, included in all the major browsers). Otherwise you have to include a polyfill
* Y.Object has been renamed to Y.Map
* Y.Map exchanges `.val(name [, value])` in favor of `.set(name, value)` and `.get(name)`
* Y.Map `.get(name)` returns a promise, if the value is a custom type
* The Connector definition slightly changed (I'll update the wiki)
* The Type definitions completely changed, so you have to rewrite them (I'll rewrite the article in the wiki)
* Support for several packaging systems
## Contribution
I created this framework during my bachelor thesis at the chair of computer science 5 [(i5)](http://dbis.rwth-aachen.de/cms), RWTH University. Since December 2014 I'm working on Yjs as a part of my student worker job at the i5.
## License
Yjs is licensed under the [MIT License](./LICENSE.txt).