Programming Languages for Mobile Code Tommy Thorn

Sun's announcement of the programming language Java more than anything popularized the notion of mobile code, that is, programs travelling on a heterogeneous network and automatically executes upon arrival at the destination. We describe several classes of mobile code and we extract their common characteristics, where security proves to be one of the major concerns. With these characteristics as reference points, we examine six representative languages proposed for mobile code. The conclusion of this study leads to our recommendations for future work, illustrated by examples of ongoing research. Les langages de programmation pour le code mobile R esum e : L'annonce du langage de programmation Java de Sun a contribu e fortement a populariser la notion de code mobile, c'est-a-dire de programmes transmis a travers un r eseau h et erog ene et ex ecut e \\ a la vol ee". Nous d ecrivons plusieurs classes de code mobile et nous extrayons leurs caract eristiques communes. La s ecurit e (au sens de conndentialit e et d'int egrit e notamment) est une des pr eoccupations majeures pour cette classe de lan-gages. Avec ces caract eristiques comme points de r ef erence, nous examinons six langages repr esentatifs propos es pour le code mobile. La conclusion de cette etude nous am ene a des recommandations pour des pistes de recherche futures, illustr ees par des examples de travaux en cours. Programming languages for mobile code 3 1 Why mobile code The expression`mobile code' is used with various diierent meanings in the literature. Just to take three examples, let us cite: The term mobile code describes any program that can be shipped unchanged to a heterogeneous collection of processors and executed with identical semantics on each processor ATLLW96].. .. mobile code, an approach where programs are considered as documents, and should therefore be accessible, transmitted and displayed (i.e., evaluated) as any other document Rou96b]. Mobile agents are code-containing objects that may be transimitted between communicating participants in a distributed system Kna96]. In this survey we will refer to mobile code as software that travels on a heterogeneous network, crossing protection domains, and is automatically executed upon arrival at the destination. Protection domains can be as big as a corporate network and as small as a personal hand held digital assistant. We believe that this characterization is general enough to encompass most usages and precise enough to exhibit the distinctive features of this …