In this tutorial you’ll learn how to build a stateful serverless Node.js application and deploy it to Akka Serverless

Akka Serverless provides an execution environment for your Cloudstate services. Cloudstate enables you to write stateful serverless applications to avoid the need to fetch data for every new request your application needs to handle. In this tutorial you’ll learn how to build and deploy a stateful serverless Node.js application.

You will create the new project using&nbsp;<code>npm</code>. Cloudstate projects rely on gRPC and Protobuf to communicate with other services. You will add gRPC, Protobuf, and Cloudstate dependencies to the&nbsp;<code><code class="inline-code">package.json</code></code>&nbsp;file and scripts to compile the Protobuf files and start the gRPC server. Finally, you will create a&nbsp;<code><code class="inline-code">.js</code></code>&nbsp;file as an entry point to the application.<br>

Cloudstate projects rely on gRPC and Protobuf to communicate with other services. The dependencies&nbsp;<code><code class="inline-code">@grpc/proto-loader</code></code>,&nbsp;<code><code class="inline-code">google-protobuf</code></code>, and&nbsp;<code><code class="inline-code">grpc</code></code>&nbsp;make sure your project works with those formats. The&nbsp;<code><code class="inline-code">cloudstate</code>&nbsp;</code>dependency is a language library that makes building Cloudstate projects more straightforward.

shoppingcart

You define message types in a&nbsp;<code><code class="inline-code">.proto</code></code>&nbsp;file along with a service that specifies the remote procedure calls.

The messages you define in&nbsp;<code><code class="inline-code">cart.proto</code></code>&nbsp;are received by your service as requests and are sent back as responses. Message definitions are aggregates that contain a set of typed fields. Each Cloudstate Entity requires a key, which is defined by the annotation&nbsp;<code><code class="inline-code">[(.cloudstate.entity_key) = true]</code></code>. Cloudstate uses the entity key to know which instance of an entity a command is for.

To use the messages with the entity implementation, add a&nbsp;<code>ShoppingCart</code>service, which will define the remote procedure calls for the messages.&nbsp;

Next, create your&nbsp;<code><code class="inline-code">.js</code></code>&nbsp;file to implement the shopping cart.<br>

Add functions for the remote procedure calls

An entry point tells the Node engine where to find the Entity implementation. Use&nbsp;<code><code class="inline-code">index.js</code></code>&nbsp;as the entry point to start the shopping cart:

It is good practice to add unit tests as you go along. Follow the procedures below to create tests and run them.

The functions to manage the cart correspond to the Protofuf definitions and the remote procedure calls you implemented.

You will add a&nbsp;<code><code class="inline-code">before</code></code>&nbsp;function that starts a new instance of the Shopping Cart server and connects to it using a gRPC connection. Since it’s on your local machine, where you do not have ssl certificates, it creates an insecure connection. The&nbsp;<code><code class="inline-code">after</code></code>&nbsp;function stops the gRPC server when all tests are completed.

After testing, you are ready to package your application and deploy to Akka Serverless.

Akka Serverless Shopping Cart

Leon Stigter

Introduction

Before you begin