Coming from Arena

The block vocabulary here is close to Arena's flowchart modules, and the expression functions keep the SIMAN names. The difference is the medium: a model is a JSON file you run from a command line or from Python. This repository has no editor and no animation.

Modules and blocks

Arena	Here
Create, Dispose	CREATE, DISPOSE
Process (Seize Delay Release, Delay, ...)	PROCESS with the same action values
Seize, Delay, Release	SEIZE, DELAY, RELEASE
Decide (by chance, by condition, N-way)	DECIDE, modes "Chance" and "Condition"
Assign	ASSIGN; attributes are entity.<name>, variables are variables
Record, tallies and counters	RECORD; its statistics are in the user_summary frame
Batch, Separate	BATCH, SEPARATE; DUPLICATE for copies
Hold (wait for signal, scan for condition, infinite)	HOLD, modes "Signal", "Condition", "Infinite"
Signal	SIGNAL
Match	MATCH
Station, Route, Sequence	STATION, ROUTE and sequences
Transporter, Request, Transport, Free	TRANSPORT with fleets on a path network
Conveyor, Access, Convey, Exit	CONVEYOR
Resource, Set, Schedule, Failure	resources, resource_sets, schedules, failures
Submodel	SUBMODEL, with parameters
Run Setup: replications, warm-up, length	simulation.replications, warmup, time_limit
Input Analyzer	naga fit
Process Analyzer	naga scenarios (common random numbers, paired comparison)
OptQuest	naga optimize (a pattern search, or Optuna when installed), naga doe

All block parameters are in the block reference.

Expressions

TNOW, NQ(name), NR(name), MR(name), EXPO(mean), UNIF(low, high), NORM(mean, sd), TRIA(low, mode, high) and DISC(...) exist under those names (expression reference). Two things differ:

• DISC takes value and probability pairs whose probabilities sum to 1, not cumulative probabilities.
• Queues are named by the resource or the store they wait for (NQ("Server")), not by a queue of their own.

Schedules and failures

A capacity schedule or a failure never interrupts a job in service: the unit goes off when the job ends. That is Arena's Wait rule. The Ignore and Preempt schedule rules are not offered; preemption exists between jobs, by priority, on a PROCESS block.

What is missing here

• An editor, animation and a run controller with a picture. naga run --player writes an HTML file that replays one replication; nothing more.
• A reader for .doe files. A model is rebuilt, by hand or through the agent tools.
• VBA and user-coded SIMAN. The nearest thing is a LOGIC block, a Python class you write.
• OptQuest's search methods. naga optimize is a simpler search with a replication budget.

What you gain

Model files you can diff and merge (naga diff, naga merge), assertions that run in CI (naga check), stocks and flows and agents in the same model, and a model an LLM agent can build and run through tools.

A good first file to read is nagasim/models/job_shop_routed.json: stations, routes and sequences (gallery).