Multiway dataflow constraint systems (MDCS) is a programming model where statements are not executed in a predetermined order. Rather, individual methods are selected from specific method sets and then executed to achieve a desired global state. The selection is done by a planner, which typically bases the choice of methods on the history of updates to the global state. MDCS is well suited for describing user interface logic where choosing what code to execute depends in complicated ways on the history of user interactions and on data availability. User interfaces are the domain of examples in this paper.

Much of the research into MDCS has been on planning algorithms and their efficiency. Here we investigate a semantic setting for MDCS, introducing dataflow constraints as modules with explicit goals and related method sets. MDCS is defined in a similar manner, with an explicit goal and a set of supporting dataflow constraints. This enables verification and testing of methods and dataflow constraints against the goals. The exposition is based on abstract syntax for an idealised programming language with global variables. On top of this we define a modular reuse mechanism for dataflow constraints based on Goguen-Burstall institution theory. We show how this setup enables reuse in user interfaces; traditionally code that defines user interface logic is almost invariably non-reusable.

多路数据流约束系统（MDCS）是一种编程模型，其中的语句未按预定顺序执行。而是，从特定方法集中选择单个方法，然后执行以实现所需的全局状态。选择是由计划者完成的，该计划者通常根据对全局状态的更新历史来选择方法。MDCS非常适合描述用户界面逻辑，其中选择要执行的代码以复杂的方式取决于用户交互的历史记录和数据可用性。用户界面是本文示例的领域。

MDCS的许多研究都涉及计划算法及其效率。在这里，我们研究MDCS的语义设置，将数据流约束作为具有明确目标和相关方法集的模块引入。MDCS以类似的方式定义，具有明确的目标和一组支持的数据流约束。这样就可以根据目标对方法和数据流约束进行验证和测试。博览会基于具有全局变量的理想化编程语言的抽象语法。在此之上，我们基于Goguen-Burstall制度理论定义了一种用于数据流约束的模块化重用机制。我们将展示此设置如何实现用户界面中的重用。传统上，定义用户界面逻辑的代码几乎总是不可重用的。