Getting Started with DAML¶
Disclaimer: This guide is being actively developed. Expect major changes to the tutorial text and minor changes to the template application.
The goal of this tutorial is to get you up and running with full-stack DAML development. We do this through the example of a simple social networking application, showing you three things:
We do not aim to be comprehensive in all DAML concepts and tools (covered in Writing DAML) or in all deployment options (see Deploying). The goal is that by the end of this tutorial, you’ll have a good idea of the following:
- What DAML contracts and ledgers are
- How a user interface (UI) interacts with a DAML ledger
- How DAML helps you build a real-life application fast.
With that, let’s get started!
If you haven’t already, see Installing the SDK for the DAML SDK and VSCode development environment.
You will also need some common software tools to build and interact with the template project.
Running the app¶
We’ll start by getting the app up and running, and then explain the different components which we will later extend.
First off, open a terminal, clone the template project and move to the project folder:
git clone https://github.com/digital-asset/create-daml-app.git cd create-daml-app
Next we need to compile the DAML code to a DAR file:
Any commands starting with
daml are using the DAML Assistant, a command line tool in the DAML SDK for building and running DAML apps.
In order to connect the UI code to this DAML, we need to run a code generation step:
daml codegen ts .daml/dist/create-daml-app-0.1.0.dar -o daml-ts/src
Now, use Yarn to install the project dependencies and build the app:
yarn install yarn workspaces run build
You should see
Compiled successfully. in the output if everything worked as expected.
We can now run the app in two steps.
You’ll need two terminal windows running for this.
In one terminal, at the root of the
create-daml-app directory, run the script:
This script is just shorthand for
daml start with some arguments, which does a few things:
We’ll leave these processes running to serve requests from our UI.
In a second terminal, navigate to the
create-daml-app/ui folder and run the application:
cd ui yarn start
This starts the web UI connected to the running Sandbox and JSON API server. The command should automatically open a window in your default browser at http://localhost:3000. If it doesn’t, just open that link in a web browser. (Depending on your firewall settings, you may be asked whether to allow the app to receive network connections. It is safe to accept.)
You should now see the login page for the social network. For simplicity of this app, there is no password or sign-up required. To learn how to handle proper authentication, see this blog post about DAML and Auth0 or the full documentation.
First enter your name and click Log in. You should see the main screen with two panels for your friends and the entire network. Initially these are both empty as you don’t have friends yet! Go ahead and add some using the text box and Add Friend button in the top panel.
You’ll notice that the newly added friends appear in the Friends panel. However they do not yet appear in the Network panel. This is because 1. they have not signed up and are not parties on the ledger, and 2. they have not yet added you as a friend. In our social network, friendships can go in a single direction. By adding a friend, say Alice, you make yourself visible to her but not vice versa. We will see how we encode this in DAML in the next section.
To make your friendships reciprocal, open a new browser window at http://localhost:3000. (Having separate windows allows you to see both you and your friend’s screens at the same time.) Once you log in as your friend Alice, you’ll notice your name in her network. In fact, Alice can see your entire friend list in the Network panel. This is because your friend list is part of the user data that became visible when you added her as a friend.
When Alice finally adds you back as a friend, you can see her in your network as well. Just switch to the window where you are logged in as yourself - the network should update automatically.
Play around more with the app at your leisure: create new users and add more friends. Observe when a user becomes visible to others - this will be important to understanding DAML’s privacy model later. When you’re ready, let’s move on to the architecture of our app.