This paper presents ALBA, a generic library dedicated to the commissioning of mobile agents written in Prolog. This library offers a handful of mechanisms for autonomous agent creation, execution, communication and mobility, whose implementation strongly respects the principles of robustness, decentralization of data, flexibility and genericity. In this perspective, the following paper mainly focuses on ALBA architecture and implementation with an emphasis on the technical choices which were made to provide these essential features. It therefore presents an innovative migration protocol, a research algorithm of agents solely identified by their names. It exposes some considerations about communication handling in a fully decentralized environment and some ideas towards a distributed modularity of systems. It also highlights an agent model, called Reasoning Threads, that is being used on top of ALBA to program cognitive agents.