Abstract
The Hierarchical Timing Language (HTL) is a real-time coordination language for distributed control systems. HTL programs must be checked for well-formedness, race freedom, transmission safety (schedulability of inter-host communication), and time safety (schedulability of host computation). We present a modular abstract syntax and semantics for HTL, modular checks of well-formedness, race freedom, and transmission safety, and modular code distribution. Our contributions here complement previous results on HTL time safety and modular code generation. Modularity in HTL can be utilized in easy program composition as well as fast program analysis and code generation, but also in so-called runtime patching, where program components may be modified at runtime.

Abstract
This paper presents the Inter-Module Communication (IMC) protocol, a message-oriented protocol designed and implemented in the Underwater Systems and Technology Laboratory (LSTS) to build interconnected systems of vehicles, sensors and human operators that are able to pursue common goals cooperatively by exchanging real-time information about the environment and updated objectives. IMC abstracts hardware and communication heterogeniety by providing a shared set of messages that can be serialized and transferred over different means. The described protocol contrasts with other existing application level protocols by not imposing or assuming a specific software architecture for client applications. Native support can be automatically generated for different programming languages and/or computer architectures resulting in optimized code which can be used both for networked nodes and also for inter-process and inter-thread communication. The protocol has already been tested throughout various experiments led by LSTS where it has taken care of communications between vehicles, sensors and operator consoles. We are now developing the protocol in the direction of having multi-vehicle cooperation using live data from environmental sensors and mixed-initiative user interaction.

Abstract
Seaware is a publish-subscribe middleware used in multi-vehicle networked systems composed of autonomous and semi-autonomous vehicles and systems. Seaware provides a high level interface to network communications and may be deployed with a combination of heterogeneous components within a dynamic network. Seaware supports the RTPS (Real Time Publish Subscribe) protocol, underwater acoustic modems and other forms of network transport. This paper gives an overview of Seaware's implementation and its application to multi-vehicle networked systems.

Abstract
Underwater acoustic networks can be quite effective to establish communication links between autonomous underwater vehicles (AUVs) and other vehicles or control units, enabling complex vehicle applications and control scenarios. A communications and control framework to support the use of underwater acoustic networks and sample application scenarios are described for single and multi-AUV operation.

Abstract
The design and development of the Swordfish Autonomous Surface Vehicle (ASV) system is discussed. Swordfish is an ocean capable 4.5m long catamaran designed for network centric operations (with ocean and air going vehicles and human operators). In the basic configuration, Swordfish is both a survey vehicle and a communications node with gateways for broadband, Wi-Fi and GSM transports and underwater acoustic modems. In another configuration, Swordfish mounts a docking station for the autonomous underwater vehicle Isurus from Porto University. Swordfish has an advanced control architecture for multi-vehicle operations with mixed initiative interactions (human operators are allowed to interact with the control loops).

Abstract
We consider a methodology for flexible software design, runtime programming, defined by recurrent, incremental software modifications to a program at runtime, called runtime patches. The principles we consider for runtime programming are model preservation and scalability. Model preservation means that a runtime patch preserves the programming model in place for programs - in terms of syntax, semantics, and correctness properties - as opposed to an "ad-hoc", disruptive operation, or one that requires an extra level of abstraction. Scalability means that, for practicality and performance, the effort in program compilation required by a runtime patch should ideally scale in proportion to the change induced by it. We formulate runtime programming over an abstract model for component-based concurrent programs, defined by a modular relation between the syntax and semantics of programs, plus built-in notions of initialization and quiescence. The notion of a runtime patch is defined over these assumptions, as a model-preserving transition between two programs and respective states. Additionally, we propose an incremental compilation framework for scalability in patch compilation. The formulation is put in perspective through a case-study instantiation over a language for distributed hard real-time systems, the Hierarchical Timing Language (HTL). © 2011 IEEE.