We have a lovely buffet of operational transform types. Each type has many fine features, including thorough testing, browser support and documentation. Each type has its own project in this github organization.
These types have been finely aged in ShareJS's type labs, and now they're ready to enter the world and be used by everyone. We are rather proud of them.
Each type defines a set of standard methods for programatic use. You should be able to define a type using the spec then plug it directly into ShareJS (or other compatible collaborative editing systems) and use it immediately. The type defines how operations and documents are stored and manipulated, while a system like sharejs can decide where the data should be stored on disk, network protocols and all that jazz.
This repository contained three OT types. They were split to separate repositories:
This is the type you should use for normal plain-text editing. It can tranform operation with complexity N against operation with complexity M in O(N+M) time. This makes it much faster than ot-text-tp2 implementation.
This implementation features Transform Property 2 which makes it a good suit for peer-to-peer communication. Unfortunately the extra (unnecessary) complexity kills v8's optimizer and as a result ot-text-tp2 goes about 20x slower than the ot-text type. If you're using client-server library like ShareJS, you don't need TP2 property, so you should use simpler ot-text implementation,
This implementation is capable of transforming not only text but also JSON structures. It supports arbitrary inserts, deletes, and reparenting through the tree of a JSON object.
This is an OT implementation for collaboratively editing rich text documents. It was designed alongside QuillJS for editing those documents.
Each OT type exposes a single object with the following properties. Note that only name, create, apply and transform are strictly required, though most types should also include url and compose.
If you're publishing your library in npm (and you should!), the module should expose an object with a
.typeproperty (containing your type). So for example,
require('ot-text').type.namecontains the text type's name.
JSON.stringifyor you must specify serialize and deserialize functions (described below).
'right'. It exists to break ties, for example if two operations insert at the same position in a string. Both op1 and op2 must not be modified by transform. Transform must conform to Transform Property 1. That is, apply(apply(snapshot, op1), transform(op2, op1, 'left')) == apply(apply(snapshot, op2), transform(op1, op2, 'right')).
Do I need serialize and deserialize? Maybe JSON.stringify is sufficiently customizable..?
If your OT type supports transform property 2, set the tp2 property to true and define a prune function.
Transform property 2 is an additional requirement on your transform function. Specifically, transform(op3, compose(op1, transform(op2, op1)) == transform(op3, compose(op2, transform(op1, op2)).
Technically, CRDT types are a subset of OT types. Which is to say, they are OT types that don't need a transform function. As a result, anything that can handle these OT types should also be able to consume CRDTs. But I haven't tested it. If anyone wants to work with me to add CRDT support here, email me.
All code contributed to this repository is licensed under the standard MIT license:
Copyright 2011 ottypes library contributors
Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following condition:
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.