Version:
v8.0
[release notes]

# About Chi

#### Chi language

The Chi language is a modeling language for describing and analyzing the performance of discrete event systems by means of simulation. The language design is based on decades of successful analyses of various (industrial) systems, aiming to be powerful for advanced users, and easy to use for non-experts.

The language uses a process-based view. A system (and its control) is modeled as a collection of parallel running processes, communicating with each other using point-to-point communication channels. Processes do not share data with other processes, and channels are synchronous (sending and receiving is always done together at the same time), making reasoning about process behavior easier. Processes and channels are dynamic, new processes can be created as needed, and communication channels can be created or rerouted, making for a powerful specification language.

The language is designed to be formal and easily extensible. Models are written as an imperative program, with an intuitive syntax, making it easy to read and write models. A small generic set of statements can be used to describe algorithms, including assignments, if, while and for statements. This set is relatively easy to explain to non-experts, allowing them to understand the model, and participate in the discussions.

The data of the system can be modeled using both basic data types, such as booleans and integer and real numbers, as well as high level structured collections of data like lists, sets and dictionaries. If desired, processes and channels can also be part of that data. Furthermore, timers and (quasi-)random number generation distributions are available for modeling timed and stochastic systems. Features to easily specify repeated experiments, e.g. for stochastic simulation, or simulation for various inputs obtained from files, exist to support large simulation experiments.

Tutorials and manuals demonstrate the use of the language for effective modeling of system processes. More detailed modeling of the processes and e.g performance indicators, or custom tailoring them to the real situation, has no inherent limits.

For more information, see the tutorial and language reference manual.

#### Chi main application area

While the language is generic, the main application area is modeling of the operation of (manufacturing) systems. During the design process, engineers can make use of analytical models, to get answers about the operation of the system. Simulation studies can provide insights into e.g. the throughput of the system, the effect of set-up time in a machine, or how the batch size of an order will influence the flow time of the product-items.

For more information, see the Chi documentation.

#### Chi tools

The Chi toolset allows verification of properties of the actual system by means of simulation, e.g. to optimize the supervisory (logic) control of the system. To easy experimentation, the Chi language and simulator support easy specification of simulation experiments. Chi aims to make the process of verifying properties for large systems effortless.

For more information, see the tool manual.

#### Part of Eclipse ESCET

The Chi language and tools are being developed as part of the Eclipse ESCET open-source project. The Chi tools are part of the Eclipse ESCET toolkit.

For more information, see the Eclipse ESCET project website.