A Formal Model of Object Mobility in Resource-Restricted Deployment Scenarios ⋆ Einar Broch Johnsen, Rudolf Schlatte, and S. Lizeth Tapia Tarifa Department of Informatics, University of Oslo, Norway {einarj,rudi,sltarifa}@ifi.uio.no Abstract. Software today is often developed for deployment on differ- ent architectures, ranging from sequential machines via multicore and distributed architectures to the cloud. In order to apply formal methods, models of such systems must be able to capture different deployment scenarios. For this purpose, it is desirable to express aspects of low-level deployment at the abstraction level of the modeling language. This paper considers formal executable models of concurrent objects executing with user-defined cost models. Their execution is restricted by deployment components which reflect the execution capacity of groups of objects be- tween observable points in time. We model strategies for object reloca- tion between components. A running example demonstrates how activity on deployment components causes congestion and how object relocation can alleviate this congestion. We analyze the average behavior of models which vary in the execution capacity of deployment components and in object relocation strategies by means of Monte Carlo simulations. 1 Introduction Software is increasingly often developed as a range of systems. Different versions of a software may provide different functionality and advanced features, depend- ing on target users. In addition to such functional variability, software systems need to adapt to different deployment scenarios. For example, operating systems adapt to specific hardware and even to different numbers of available cores; vir- tualized applications are deployed on a varying number of (virtual) servers; and services on the cloud may need to adapt dynamically to the underlying cloud in- frastructure. This kind of adaptability raises new challenges for the modeling and analysis of component-based applications [33]. To apply formal methods to such applications, it is interesting to lift aspects of low-level deployment concerns to the abstraction level of the modeling language. In this paper we propose abstract performance analysis for formal object-oriented models, in which objects may migrate between deployment components that are parametric in the amount of concurrent processing resources they provide to their objects. The work presented in this paper is based on ABS [20], a modeling lan- guage for distributed concurrent objects which communicate by asynchronous ⋆ Partly funded by the EU project FP7-231620 HATS: Highly Adaptable and Trust- worthy Software using Formal Models (http://www.hats-project.eu).