Custom WIT example

This example shows how to combine the wasmCloud Component SDK with your custom interfaces. You can find the custom interface in wit/world.wit. It should look something like this:

wit

interface invoker {
  call: func() -> string;
}

Dependencies

Before starting, ensure that you have the following installed in addition to the Go toolchain:

• The [TinyGo toolchain][tinygo]
• [wash, the WAsmcloud SHell][wash] installed.
• wasm-tools for Go bindings

Running the example

For this example, we will be building and deploying manually rather than using wash dev since we will be demonstrating wash call which requires a stable identity to call. As you gain experience with wasmCloud, you will likely want to use wash dev to automate your development process.

First, build the component:

bash

wash build

Then you can start the host:

bash

wash up -d

Next, deploy the component:

bash

wash app deploy wadm.yaml

You should then be able to call the component:

bash

wash call invoke_example-invoker example:invoker/invoker.call
Hello from the invoker!

To clean up, run:

bash

wash app delete wadm.yaml
wash down

Bonus: Calling when running with wash dev

When running with wash dev, it uses a generated ID for the component. If you have jq installed, you can run the following command to call the component:

bash

wash call "$(wash get inventory -o json | jq -r '.inventories[0].components[0].id')" example:invoker/invoker.call
Hello from the invoker!