Towards safe distributed application development

Distributed application development is overly tedious, as the dynamic composition of distributed components is hard to combine with static safety with respect to types (type safety) and data (encapsulation). Achieving such safety usually goes through specific compilation to generate the glue between components, or making use of a single programming language for all individual components with a hardwired abstraction for the distributed interaction. In this paper, we investigate general-purpose programming language features for supporting third-party implementations of programming abstractions for distributed interaction among components. We report from our experiences in developing a stock market application based on type-based publish/subscribe (TPS) implemented (1) as a library in standard Java as well as with (2) a homegrown extension of the Java language augmented with specific primitives for TPS, motivated by the lacks of former implementation. We then revisit the library approach, investigating the impact of genericity, reflective features, and the type system, on the implementation of a satisfactory TPS library. We then discuss the impact of these features also on other distributed programming abstractions, and hence on the engineering of distributed applications in general, pointing out lacks of mainstream programming environments such as Java as well as .NET.