Types of Collaboration: Introduction

When we started XTWIP, we had a simple vision: allowing people to change the same content at the same time. We strongly believe that this can help getting more work done together, without losing time with emails, phone calls and (worst of all) meetings.

However, we soon realized that from a technical stand-point there are three fundamental ways of implementing real time collaboration. To the end-user this probably has no impact whatsoever. But for the developer who makes his/her application collaborative, it is of great importance to choose the best mix of these models:

• Event based collaboration – actions are sent over the network. The XTWIP server has the logic to execute application specific operations on its own data model.

• Object based – XML-formatted object structures are sent over the network, depending on the part that changes. The XTWIP server requires no logic to execute application specific operations.

• Data based collaboration – actions are sent over the network. The XTWIP server has no logic to execute application specific operations and it periodically polls client-sided applications for the latest data model. The server stores the data model, serves it to new clients, but it doesn’t understand the data, nor does it have the logic to change it.

• Operational Transforms (OT) based collaboration (this is the stuff Google Wave uses). The collaboration server has logic to execute general purpose editing operations (insert, delete, skip) and also the logic to “merge” these operations together. For instance, if two users send concurrent actions (almost) simultaneously, those specific actions are modified by OT when they reach their destination so that they make sense in the new context. The server stores and periodically updates the data model. However, OT is very CPU intensive and the results it produces are usually more than what most application developers need.

In the following posts, we’ll explain the differences between these types of collaboration and how you should pick the one the suits best your use case/business case.