Poplar: A Java Extension for Evolvable Component Integration

TL;DR

Poplar is a Java extension that simplifies component integration by using declarative queries and generated linking code, enabling evolvable, static, and automatic component composition.

Contribution

It introduces a novel Java extension with declarative dependencies, planning-based code generation, and a minimal specification language to improve component evolution and integration.

Findings

Enables fully automatic component integration.

Reduces breaking changes in component evolution.

Simplifies object-oriented software development.

Abstract

The Java programming language contains many features that aid component-based software development (CBSD), such as interfaces, visibility levels, and strong support for encapsulation. However, component evolution often causes so-called breaking changes, largely because of the rigidity of component interconnections in the form of explicit method calls and field accesses. We present a Java extension, Poplar, which we are currently developing. In Poplar, inter-component dependencies are expressed using declarative queries; concrete linking code, generated using a planning algorithm, replaces these at compile time. Poplar includes a minimal specification language based on typestate-like protocols and labels, and a lightweight effect system, which ensures the absence of unwanted interference between hand-written code and generated code. We give several examples of fully automatic component integration using Poplar, and demonstrate its potential to simplify object-oriented software development greatly through evolvable and statically checkable integration links.