Parcels: A fast and feature-rich binary deployment technology

While development of a software system is important, it is also very important to have suitable mechanisms for actually deploying code. Current state-of-the-art deployment approaches force the developer to structure the code in such a way that deployment is possible, thereby severely inhibiting reuse and comprehensibility of the system. This paper presents parcels, an atomic deployment mechanism for objects and source code that supports shape changing of classes, method addition, method replacement, and partial loading. The key to making this deployment mechanism feasible and fast is a pickling algorithm that allows the unpickling to be done iteratively instead of with a recursive descent parser. Parcels were developed for VisualWorks Smalltalk, and have been the default deployment mechanism the past years for thousands of customers.