Linking

Store and Instantiating Multiple Modules

A Store is an intermediate-level abstraction that collects Wasm function, global, memory, and table instances as named entities.

It simplifies creating instances when there are a lot of interdependencies, by collecting all the

In the simplest case, it allows to register single host functions, globals, memories and tables:

import com.dylibso.chicory.runtime.Store;

// instantiate the store
var store = new Store();
// registers `console.log` in the store (see the previous section for the definition of `func`)
store.addFunction(func);

However, the store also automatically exposes the exports of a module to the other instances that are registered.

// registers the `instance` created earlier (see the previous section) with the name `logger`
store.register("logger", instance);
// now the exported function `logIt` can be imported by other modules as `logger.logIt`

There is also a shorthand method to instantiate a module and register the resulting instance:

var logger2 = store.instantiate("logger2", Parser.parse(new File("./logger.wasm")));

This is equivalent to:

var external = store.toImportValues();
var m = Parser.parse(new File("./logger.wasm"));
var instance = Instance.builder(m).withImportValues(external).build();
store.register("logger2", instance);

Notice that registering two instances with the same name results in overwriting the functions, globals, memories, tables with matching names. In this case, the new logger2.logIt function overwrote the old logger2.logIt function.

The current Store is a mutable object, not meant to be shared (it is not thread-safe).

A Store does not resolve interdependencies between modules in itself: if your set of modules have interdependencies, you will have to instantiate and register them in the right order.