Prevent Collaboration Conflicts with Fine Grained Pessimistic Locking.

There are two main strategies to support the collaboration of software team members working concurrently on the same source code: pessimistic locking and optimistic locking. Optimistic locking is used far more often because a pessimistic lock on the smallest unit stored in the Software Configuration Management (SCM), which is a usually a file, often causes conflict situations, where a developer wants to change the already locked code. Optimistic locking can cause direct and indirect merge conflicts which are costly to resolve and affect productivity. The novelty of our approach is to define a meta-model for the source code (Abstract Syntax Tree) and use pessimistic locking on model artefacts and therefore allow parallel editing of the same class or even method but still preventing direct and indirect merge conflicts. Thereby the developer keeps an isolated workspace and the developer decides when to commit the finished source code. This paper introduces a concept for this solution and a prototype based on Eclipse.