The relevant source code is in the Dream2 folder.

We initially need to assign a name to the current host Host1.

Consts.hostName = "Host1";

Now on Host1 we can define a Var myVar that is visible remotely. The var myVar constains a string, it is advertised with the name exVar and it is initialized to the value AAA. Later on the value is changed to BBB.

Var<String> myVar = new Var<String>("exVar", "AAA");
myVar.set("BBB");

On a different host, Host2 we can read the var defined on Host1 whose name is exVar. We can also define a signal that builds a computation on top of it.

RemoteVar<String> rv = new RemoteVar<String>("Host1", "exVar");

Signal<String> s = new Signal<String>>("s", () -> {
			return rv.get() + "XXX";	
		}, rv);

If rv is not available yet, ... More examples:

Var<Integer> a = new Var<>("a", Integer.valueOf(1));
	  
Var<Integer> b = new Var<>("b", Integer.valueOf(2));
	  
Signal<Integer> c =
    new Signal<>("c", () -> a.get() + b.get(), a, b);

Another example:

Var<List<Integer>> lst = new Var<>("lst", new ArrayList<Integer>());
	  
Signal<Integer> n =
    new Signal<>("n", () -> lst.get().size(), lst);
	  
    lst.modify(self -> {
        self.add(1);
	self.add(2);
	self.add(3);
    });

When using Atomic_Consistency it is required to lock a Var before reading its value.

	LockToken lock = DreamClient.instance.readLock(new HashSet<>("exVar@Host1"));
	String value = rv.get();
	DreamClient.instance.unlock(lock);

In the dream.examples.util-package you can find the class Client which does all the needed setup for Dream. It starts the DreamServer if it is not already running, sets the Client Name and connects to the Dependency Graph. It also provides some additional utilities.

public class MyClass extends Client {

	public MyClass() {
		super("ClientName");
		
		// Here you can add you Vars/Signals
		Var<String> myVar = new Var<>("myVar", "value");
	}
}

It can also wait for defined Vars to be available:

public class OtherClass extends Client {

	public OtherClass() {
		super("OtherName");
		// The super class blocks until myVar@ClientName is available
		RemoteVar<String> theirVar = new RemoteVar<>("ClientName", "myVar");
	}
	
	@Override
	protected List<String> waitForVars() {
		return Arrays.asList("myVar@ClientName");
	}
	
	@Override
	protected void init() {
		// The code here is executed before the the super class blocks
	}
}

Alessandro Margara

Tobias Becker

Kim Berninger and Michael Raulf - IMPL Project