Active C# Compiler

Active C# is a variant of Microsoft’s C# that enhances the basic language with a direct support for concurrency and a new model for object communication. The C# compiler of the Shared Sources Common Language Infrastructure (SSCLI) served as a basis to extend the compiler. Modifications mainly concern the enhancement of C# with an active object concept and a novel communication paradigm based on formal dialogs.

Please send bug reports to Raphael Guentensperger (guentensperger at inf.ethz.ch)

Active C# [pdf] - Conference Paper, .NET Technologies’2004, Plzen
Active C# [ppt] - Conference Talk, .NET Technologies'2004, Plzen

Compiler & Library:

Running binaries (07.09.2004)
Dialog Library (binary) (Version 0.1.9.0)
Dialog Library (source) [ html | cs ] (Version 0.1.9.0)
Dialog Library documentation (07.09.2004)
Compiler source code (Directory: \sscli\clr\src\csharp) (07.09.2004)
SSCLI 1.0 - 11/01/2002

Installation instructions:

Download and unpack the compiler binaries.
Download the Dialog Library and store it at the place where your executable will run.
Compile your Active C# source file and run it...

Active C# Sample programs:
- Santa Claus ++
  - Source Code (html)
  - Source Code (.cs file)
- Robot Walk - remote dialogs with graphical frontends
  - Source Code (html) - dialog declaration
  - Source Code (.cs file) - dialog declaration
  - Source Code (html) - server part
  - Source Code (.cs file) - server part
  - Source Code (html) - client part
  - Source Code (.cs file) - client part
- The Next Common Meeting Time
  This is an exercise that I learnt from Jay Misra. A secretary needs to arrange a meeting for a group of managers at the next possible time. Each manager provides an agenda service that takes a proposal (earliest possible day) and returns the next possible meeting day for this manager.
  We declare two classes Manager and Coordinator (secretary). The basic idea of the program is now this: Each manager is an active object that creates a dialog with the coordinator and then continuously accepts proposals from the coordinator and returns the next possible availability. In turn, the coordinator stores the maximum of the returned availabilities and continues querying the managers until a fix point is reached. In particular note that multiple instances of one and the same dialog AllocMeetinng run concurrently.
  - Source Code (html)
  - Source Code (.cs file)
- The Monkey Rock Problem
  This is a folklore exercise that comes in different versions. The northern monkeys live on the northern rock that provides water but no food. Conversely, the southern monkeys live on the southern rock that provides food but no water. However, both the northern and southern monkeys have to eat and to drink! There is a small rope between the two rocks. The rope can carry up to MaxOnRope monkeys. Concurrent crossing in both direction is not possible.
  Each monkey is modelled as an active object that creates and maintains a permanent dialog with a coordinator who coordinates the rope. This example shows a two-phase dialog: the logics for crossing the rope from north to south and from south to north are textually separate. This releases the monkey objects from capturing their current location.
  - Source Code (html)
  - Source Code (.cs file)
- Frisbee
  I found this exercise on the Internet site of the Binghamton University. Two or more people are playing a game of frisbee with two or more frisbees. Initially, the frisbees are given to different people and the numbers of people and frisbees are known. The players stand around in a circle, and the frisbees are thrown clockwise along the circle. Each person receives a frisbee and throws it to the next person over. Unfortunately, if a frisbee is thrown at a person when he already has another, he will drop it – we do not want that case to happen.
  Here, we need to model a ring consisting of active player objects that communicate with their clockwise neighbor. Note that within each player two activities run concurrently: a) his own behavior and b) the dialog with his counterclockwise neighbor. Both activities within each player operate on the shared variable nofFrisbees (0 or 1).
  - Source Code (html)
  - Source Code (.cs file)
- Parking Lot
  In this example there is a parking lot administrator that handles the assignment of parking lots to cars requesting them. Cars can ask for a list of free parking lots and make their decission for one of them. The administrator finally tells them if their decission is still valid. If it is, the car parks in the appropriate lot until it sends the Leave command which marks the end of the dialog and sets the parking lot free again
- Rental Service
  This is a more generalized example of the Parking Lot example but implemented with local dialogs.
  - RentalService Code (html)
  - RentalService Code (.cs file)

Microsoft Shared Source License

News:

Compiler & Sources available now. (28.05.2004)
A new Version will be available by the end of July. (30.06.2004)
A new Version uploaded. (30.07.2004)
Small Language Change:
- Keyword keyword is not part of the language anymore
- Keywords of a dialog are of the type declared through the dialog declaration.
  Example: Declaration: dialog D { k1, k2 }; Use: D kw = D.k;
- To specify the dialog type itself, the dialog name has to be preceded by dialog.
  Example: dialog D myDialog = new C.DImpl; // instantiates a dialog of Type D implemented as DImpl in class C and assigns it to myDialog
Update of compiler & library (small bugfix) / library documentation added (07.09.2004)
Parking Lot example added / library source code added (13.10.2004)