Language tutorial

This tutorial introduces the CIF language. It explains the general idea behind the concepts of the language, and shows how to use them, all by means of examples. The tutorial is focused on giving a short introduction to CIF, and does not cover all details. It is recommended reading for all CIF users.

Introduction

CIF is primarily used to create models of physical systems and their controllers, describing their behavior. However, CIF is a general-purpose modeling language, and can be used to model practically anything, ranging from physical real-world systems to abstract mathematical entities.

CIF supports discrete event models, that are mostly concerned with what happens, and in which order. CIF also supports timed systems, where timing plays an explicit role, and hybrid systems, which combine the discrete events with timing. This makes CIF suitable for modeling of all kinds of systems.

The CIF tooling puts a particular focus on supporting the entire development process of controllers. However, just as the CIF language, the CIF tooling can be applied much more generally. The tooling allows among others specification, supervisory controller synthesis, simulation-based validation and visualization, verification, real-time testing, and code generation.

CIF originally stood for Compositional Interchange Format for hybrid systems. As the language has since evolved beyond its original purpose, the name 'CIF' is nowadays only used in its abbreviated form.

Lessons

Several lessons are available, grouped into the following categories:

Basics
Data
Types and values
Scalable solutions and reuse (1/2)
Time
Channel communication
Functions
Scalable solutions and reuse (2/2)
Stochastics
SVG visualization and interaction
Text
Language extensions

The lessons introduce new concepts, one by one, and are meant to be read in the given order.

Basics

Automata: Explains automata, locations, events, edges, transitions, and more.
Synchronizing events: Explains event synchronization, enabledness, traces, and state spaces.
Non-determinism: Explains multiple causes of non-determinism.
Alphabet: Explains alphabets for both individual automata and entire specifications.
Event declaration placement: Explains the placement of event declarations.
Shorter notations: Explains several shorter notations, including self loops, declaring multiple events with a single declaration, multiple events on an edge, and nameless locations.

Data

Discrete variables: Explains discrete variables, guards, and updates.
Discrete variable value changes: Explains how and when discrete variables can change value.
Location/variable duality (1/2): Explains the duality between locations and variables using a model of a counter.
Location/variable duality (2/2): Explains the duality between locations and variables using a model of a lamp.
Global read, local write: Explains the concepts of global read and local write.
Monitoring: Explains monitoring, self loops, and monitor automata.
Old and new values in assignments: Explains old and new values of variables in assignments, multiple assignments, and the order of assignments.
The tau event: Explains the tau event.
Initial values of discrete variables: Explains initialization of discrete variables, including the use of default values and multiple potential initial values.
Initialization predicates: Explains initialization in general, and initialization predicates in particular.
Using locations as variables: Explains the use of locations as variables.
State (exclusion) invariants: Explains state (exclusion) invariants.
State/event exclusion invariants: Explains state/event exclusion invariants.

Types and values

Types, values, and expressions: Explains the concepts of types, values, and expressions, as an introduction for the other lessons in this category.
Values overview: Provides an overview of the available values, and divides them into categories.
Integers: Explains integer types, values, and commonly used expressions.
Ranged integers: Explains ranged integers.
Reals: Explains real types, values, and commonly used expressions.
Booleans: Explains boolean types, values, and commonly used expressions.
Strings: Explains string types, values, and commonly used expressions.
Enumerations: Explains enumeration types, values, and commonly used expressions.
Tuples: Explains tuple types, values, and commonly used expressions.
Lists: Explains list types, values, and commonly used expressions.
Bounded lists and arrays: Explains bounded lists, arrays, and their relations with regular lists.
Sets: Explains set types, values, and commonly used expressions.
Dictionaries: Explains dictionary types, values, and commonly used expressions.
Combining values: Explains how to combine values of different types.
If and switch expressions: Explains if and switch expressions.

Scalable solutions and reuse (1/2)

Constants: Explains the use of constants.
Algebraic variables: Explains the use of algebraic variables.
Algebraic variables and equations: Explains the use of equations to specify values of algebraic variables.
Type declarations: Explains the use of type declarations.

Time

Timing: Introduces the concept of timing.
Continuous variables: Explains the use of continuous variables.
Continuous variables and equations: Explains the use of equations to specify values of continuous variables.
Equations: Show the use of equations for both continuous and algebraic variables, by means of an example of a non-linear system.
Variables overview: Provides an overview of the different kinds of variables in CIF, and their main differences.
Urgency: Explains the concept of urgency, as well as the different forms of urgency.
Deadlock and livelock: Explains the concepts of deadlock and livelock.

Channel communication

Channels: Explains point-to-point channels and data communication.
Dataless channels: Explains void channels that do not communicate any data.
Combining channel communication with event synchronization: Explains how channel communication can be combined with event synchronization, further restricting the communication.

Functions

Functions: Introduces functions, and explains the different kind of functions.
Internal user-defined functions: Explains internal user-defined functions.
Function statements: Explains the different statements that can be used in internal user-defined functions.
Functions as values: Explains using functions as values, allowing functions to be passed around.

Scalable solutions and reuse (2/2)

Automaton definition/instantiation: Explains using automaton definition and instantiation for reuse.
Parametrized automaton definitions: Explains parametrized automaton definitions.
Automaton definition parameters: Explains the different kinds of parameters of automaton definitions.
Groups: Explains hierarchical structuring using groups.
Group definitions: Explains groups definitions and parametrized group definitions.
Imports: Explains splitting CIF specifications over multiple files using imports.
Imports and libraries: Explains how to create libraries that can be used by multiple CIF specifications using imports, as well as how to use imports to include CIF specifications from other directories.
Imports and groups: Explains how imports and groups interact.
Namespaces: Explains namespaces, and how they can be used together with imports.
Input variables: Explains input variables, how they can be used for coupling with other models and systems, and their relation to imports.

Stochastics

Stochastics: Introduction to stochastic distributions, which allow for sampling, making it possible to produce random values.
Discrete, continuous, and constant distributions: Explains the different categories of stochastic distributions: discrete, continuous, and constant distributions.
Pseudo-randomness: Explains how computers implement stochastics using pseudo-random number generators, and how this affects the use of stochastics in CIF.

SVG visualization and interaction

SVG visualization: Introduction to SVG visualization, which allows to connect an image to a CIF model and update the image based on the state of the model.
First example: A first simple example of SVG visualization.
Inkscape: Explains how to use the Inkscape drawing program to edit SVG images.
Sun/moon example: An example of using groups of SVG objects, as well as controlling the visibility of objects based on the current locations of automata.
Walk example: An example of of using groups of SVG objects, positioning them, and changing their position using an output mapping, as well as using the scale standard library function, text formatting, multiple values in an output mapping, and multiple format specifiers in a format pattern.
Rate example: An example of using literal values in output mappings, as well using simple solution to solve visualization problems.
Workstation example: An example of fixed-value and clock-based object widths, changing the fill color of objects, updating multiple attributes of an SVG object, specifying colors in SVG, and improving scalability by reusing mappings.
Tank example: An example of using the scale standard library function, as well as how inverting the y-axis can reduce the number of output mappings.
Lamps example: An example of hierarchical scalability of SVG images by reusing mappings, as well as copying elements and moving them to the desired position.
Buffers/products example: Another example of hierarchical scalability of SVG images by reusing mappings, as well as copying (copied) elements and moving them to the desired position.
SVG interaction: Explains how to extend a model to couple it to an image for interaction via a visualization.

Text

Print output: Introduces print output by means of print declarations, which allows to print custom text from the model at runtime, either to the console or to a file.
Print output examples: Explains print output by means of examples.
Text formatting: Explains text formatting by means of examples.

Language extensions

Supervisory controller synthesis: Explains how to extend a model to make it suitable for supervisory controller synthesis.
Annotations: Explains how to annotate elements of the specification with extra information.