Optimisation Service Client

A Java client for Optimatika's optimisation service. Build an LP, QP or MIP model in code, submit it to a remote solver, and get the result back — all with plain Java and zero dependencies.

The optimisation service does not require this – this client simply tries to make things simpler for users of that service. The optimisation server is a paid for service available at AWS, Azure and GCP. Without access to a server instance, this client code is of no use.

Design

• No dependencies. The entire client is plain Java using only the standard library. No JSON library, no HTTP framework, no build plugins beyond the compiler.
• Simple types. The API uses BigDecimal, String, List, Map, and Future. No custom exception hierarchies, no generic type parameters, no framework annotations.
• Minimal code. Eight source files, under 1400 lines total. The model builder, HTTP client, and result types are all in a single package.
• Java 11+. Not required to be on the latest Java version.

Usage

// Connect to the service
OptClientV01 client = OptClientV01.newInstance("https://your-service-host");

// Build a model
OptModel model = client.newModel();

OptVariable x = model.newRealVariable("x").lower(0);
OptVariable y = model.newRealVariable("y").lower(0);

model.newConstraint("budget").set(x, 1).set(y, 1).upper(10);

model.objective().set(x, 3).set(y, 5);

// Solve remotely (asynchronous)
OptResult result = model.maximise().get();

System.out.println("Optimal: " + result.isOptimal());
System.out.println("Value:   " + result.getValue());
System.out.println("x = " + x.doubleValue());
System.out.println("y = " + y.doubleValue());

Classes

Class	Role
OptClientV01	HTTP client — submits models and polls for results
OptModel	Model builder — variables, constraints, objective, serialisation
OptVariable	Decision variable (real, integer, or binary)
OptConstraint	Linear/quadratic constraint with bounds
OptObjective	Objective function (linear/quadratic)
OptExpression	Base for constraints and objective — holds coefficients
OptResult	Immutable result — feasible/optimal status, objective value, solution vector

Two layers

The client is split into two distinct layers:

• OptClientV01 is a thin HTTP client wrapper. It knows how to submit bytes to the server and parse the JSON response, but knows nothing about what a model looks like. You can use it standalone to submit MPS files or any other format the server supports.
• OptModel is a model builder. It provides the fluent API for variables, constraints, and objectives, handles serialisation, and manages the poll loop and result mapping. It delegates all HTTP communication to an OptClientV01 instance passed to its constructor.

This separation means you can use the HTTP client directly without the model builder, or replace the model builder without touching the HTTP layer.

The putOnQueue and pollResult method signatures match ojAlgo's Optimisation.ModelSubmitter and Optimisation.ResultPoller functional interfaces, so they can be passed directly as method references.

How it works

1. You build a model using OptModel and its fluent API.
2. Calling maximise() or minimise() serialises the model and POSTs it to the server.
3. The client polls the server until the solver finishes.
4. The result is parsed, solution values are written back to the variables, and the Future<OptResult> completes.

Models can also be submitted directly as MPS files via OptClientV01.putOnQueue().

Use with ojAlgo

If you use ojAlgo, you can wire this client into ExpressionsBasedModel so that calling submit() solves remotely:

OptClientV01 client = OptClientV01.newInstance("https://your-service-host");

Optimisation.Environment environment = Optimisation.newEnvironment();
environment.setRemoteSolver(client::putOnQueue, client::pollResult);

ExpressionsBasedModel model = environment.newModel();
// ... build your model ...

Future<Optimisation.Result> future = model.submit(Optimisation.Sense.MIN);
Optimisation.Result result = future.get();

Building

mvn package

License

This software is released into the public domain — see UNLICENSE.