Reactive programming has recently gained popularity as a paradigm that is well-suited for developing event-driven and interactive applications. It facilitates the development of such applications by providing abstractions to express time-varying values and automatically managing dependencies between such values. A number of approaches have been recently proposed embedded in various languages such as Haskell, Scheme, JavaScript, Java, .NET, etc. This survey describes and provides a taxonomy of existing reactive programming approaches along six axes: representation of time-varying values, evaluation model, lifting operations, multidirectionality, glitch avoidance, and support for distribution. From this taxonomy, we observe that there are still open challenges in the field of reactive programming. For instance, multidirectionality is supported only by a small number of languages, which do not automatically track dependencies between time-varying values. Similarly, glitch avoidance, which is subtle in reactive programs, cannot be ensured in distributed reactive programs using the current techniques. INTRODUCTIONToday's applications are increasingly becoming highly interactive, driven by all sorts of events originating from within the applications and their outside environment. Such event-driven applications maintain continuous interaction with their environment, processing events and performing corresponding tasks such as updating the application state and displaying data [Pucella 1998]. The most interactive part of such appli- Author's addresses: Software Languages Lab, Vrije Universiteit Brussel, Pleinlaan 2, 1050 Elsene, Brussels, Belgium; email: ebainomu@vub.ac.be Permission to make digital or hard copies of part or all of this work for personal or classroom use is granted without fee provided that copies are not made or distributed for profit or commercial advantage and that copies show this notice on the first page or initial screen of a display along with the full citation. Copyrights for components of this work owned by others than ACM must be honored. Abstracting with credit is permitted. To copy otherwise, to republish, to post on servers, to redistribute to lists, or to use any component of this work in other works requires prior specific permission and/or a fee. Permissions may be requested from Publications Dept., ACM, Inc., 2 Penn Plaza, Suite 701, New York, NY 10121-0701 USA, fax +1 (212) 869-0481, or permissions@acm.org. cations is usually the GUI, which typically needs to react to and coordinate multiple events (e.g., mouse clicks, keyboard button presses, multi-touch gestures, etc.).These applications are difficult to program using conventional sequential programming approaches, because it is impossible to predict or control the order of arrival of external events and as such control jumps around event handlers as the outside environment changes unexpectedly (inverted control, i.e., the control flow of a program is driven by external events and not by an order specified by the programmer). Moreo...

The rise of mobile computing platforms has given rise to a new class of applications: mobile applications that interact with peer applications running on neighbouring phones. Developing such applications is challenging because of problems inherent to concurrent and distributed programming, and because of problems inherent to mobile networks, such as the fact that wireless network connectivity is often intermittent, and the lack of centralized infrastructure to coordinate the peers.We present AmbientTalk, a distributed programming language designed specifically to develop mobile peer-to-peer applications. AmbientTalk aims to make it easy to develop mobile applications that are resilient to network failures by design. We describe the language's concurrency and distribution model in detail, as it lies at the heart of AmbientTalk's support for responsive, resilient application development. The model is based on communicating event loops, itself a descendant of the actor model. We contribute a small-step operational semantics for this model and use it to establish data race and deadlock freedom.

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International audienceBecause of the dynamic nature of mobile ad hoc networks and the applications running on top of them, these applications have to be conceived as event-driven architectures. Such architectures are hard to program because coordination between concurrent and distributed mobile components has to be expressed by means of event handlers or callbacks. Applications consisting of disjoint event handlers that are independently triggered (possibly by their environment) exhibit a very implicit control flow that is hard to grasp. This paper presents a visual dataflow language tailored towards mobile applications to express the interaction between mobile components that operate on data streams. By using a visual dataflow language as a separate coordination language, the coarse grained control flow of a mobile application can be specified visually and separately from the fine grained control flow. In its turn, this allows a very explicit view on the control flow of the entire mobile application

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