Ambient-Oriented programming is a paradigm geared towards mobile computing. Mobile hardware (such as cell phones) is mostly equipped with wireless networking, allowing it to collaborate with nearby devices in its environment. However, because wireless network links are volatile (basically: when devices move out of wireless range, the connection drops), network failures occur much more frequently than in traditional networks. The basic assumption of the Ambient-Oriented Programming paradigm is that languages should incorporate network failures at the heart of their programming model, and not treat them as “exceptions”.

Our own experimental language, AmbientTalk, differs from most traditional languages because:

• It employs a purely event-driven concurrency framework, founded on actors.
• It abandons the RPC abstraction in favor of asynchronous, non-blocking message passing. Because the system automatically buffers such messages while the receiver of the message is disconnected, the programmer can make abstraction from temporary network failures by default.
• It has built-in programming language constructs for objects to discover one another in the local ad hoc network. Peer-to-peer service discovery is built into the language.
• It features a dynamic OO kernel language built upon the principles of prototype-based programming (based on Scheme, Self and Smalltalk). The kernel language supports reflection using mirrors, which provide access to an extensive metaobject protocol, making the language extensible from within itself.
• The language syntax derives primarily from the ‘curly brace’ family of languages, but it mixes in the keyworded messaging syntax from Smalltalk as well. This, together with AmbientTalk’s lightweight block syntax, enables you to easily build your own control structures. Like many other dynamic and functional languages, AmbientTalk embraces the use of blocks to express higher-order, functional patterns.
• The current implementation of AmbientTalk embraces the JVM as a platform. It’s easy for AmbientTalk programs to use Java libraries, and it’s easy for Java objects to use !AmbientTalk as an embedded scripting language. This interaction is safe: even when AmbientTalk objects are “exposed” to the JVM, JVM threads cannot violate the concurrency constraints of AmbientTalk’s actor model.

Check out the introduction to AmbientTalk for a hands-on example showing you the benefits in actual code. Alternatively, glance at the key expressions in the language to get a 60-second overview of the language’s design and intents.

The screencast below shows how to implement a simple echo server for mobile ad hoc networks. It introduces AmbientTalk’s support for peer-to-peer service discovery, asynchronous messages, futures and how remote object references are resilient to network failures by default:

AmbientTalk is not our only research artifact. We have ported the ideas of Ambient-oriented Programming to Scheme, leading to the iScheme language. There is also CRIME, a data-driven programming language which explores the logic programming paradigm to tackle similar coordination issues in mobile ad hoc networks

AmbientTalk’s mirages have inspired the development of proxies in ECMAScript harmony.