JSimul

Java implementation of a SimPy-style discrete-event simulation core. Built with Java 21 and Maven.

Modules

• sim: simulation core (events, processes, conditions) plus collections/resources (Resource, Store, Container, Priority/PreemptiveResource) and examples.
• basic, plat: other project modules (not covered here).

Build & Test

• Prerequisite: JDK 21, Maven 3.9+.
• Build core module: cd sim && mvn -q package
• Run tests: cd sim && mvn test

Quick Start

Key primitives live in com.jsimul.core:

• Environment: schedules events and runs simulations (env.run(...), env.timeout(...), env.process(...)).
• Event / Timeout: awaitable events with callbacks; Timeout triggers after a delay.
• Process: user logic running in a task; uses ProcessContext.await(Event) to block on events.
• Condition (AnyOf / AllOf): compose events.

Resources live in com.jsimul.collections:

• Resource, PriorityResource, PreemptiveResource: capacity-constrained shared resources with request/release.
• Store, FilterStore, PriorityStore: item queues with optional filtering/priority.
• Container: continuous quantity put/get.

Examples

Examples are under sim/src/main/java/com/jsimul/examples and use logging to show steps:

• BasicUsageExample: two processes waiting on timeouts.
• ResourceUsageExample: queued jobs requesting/releasing a single machine.
• ConditionExample: demonstrates AnyOf/AllOf composition.
• FlowLineScenario: full flow-line (A->F) with vehicles moving parts; sweeps vehicle count to meet a daily target.

Run an example (from project root after build):

cd sim
mvn -q -DskipTests package
java -cp target/classes com.jsimul.examples.BasicUsageExample

Replace class with any example to explore.

Logging

Examples use java.util.logging to emit INFO-level milestones. Adjust the global logging config (e.g., -Djava.util.logging.config.file=...) to control verbosity when running examples. Developers can add similar logging to processes and callbacks to aid troubleshooting.