Component Assemblies and Component Runtimes

We propose a component programming language that supports an integrated notion of both compile-time and runtime component. The centerpiece of this paper is the static, compile time notion of assembly, complementing our previous work on the dynamic, runtime notion of cell. An assembly is a declarative, stateless piece of code that facilitates code combination. It offers explicit typed interfaces to outsiders, called linkers, which can be used to link smaller assemblies into bigger, compound assemblies. Each assembly may in turn be loaded at run-time, producing a cell in the runtime environment. A cell is a dynamic, stateful component that interacts with other cells via explicit runtime interfaces. Thus, the static assemblies and the dynamic cells are fully integrated. Assemblies may also be dynamically linked into a running cell, thereby expanding its code base on runtime. We present the model and the concepts, and then go on to define a toy language supporting assemblies and cells. We precisely define the langauge via a formal operational semantics and a set of typing rules.