Section 2: Start a project

Language

We provide a template so that you don’t need to create the shopping cart project structure along with configuration and build files. The instructions below describe how to run the template and open the resulting project in IntelliJ. If you are using a different IDE, substitute as necessary.

1. Download the empty template

The starting template is available as downloadable zip file with Java or Scala sources. Select your preferred language (Java/Scala):

Java: Download Java sources.
Scala: Download Scala sources.

Unzip the file and you should have 3 directories:

shopping-analytics-service
shopping-cart-service
shopping-order-service

In the first part of the tutorial we will work with the shopping-cart-service and we will use the others in later steps of the tutorial.

Change to the new shopping-cart-service project directory and try to build it with:

Java

mvn compile

Scala

sbt compile

2. Open the project in IntelliJ

If you are using IntelliJ, follow these steps to open the project:

From the File > Open menu, select shopping-cart-service/build.sbt shopping-cart-service/pom.xml.
Select Open as project.

3. Run Docker and Docker Compose

Follow these steps to prepare for running shopping cart:

From the root project directory, run the following command:
```
docker compose up -d
```
This command will build and run the containers. The -d flag starts the containers in detached mode. Containers started in detached mode exit when the root process used to run the container exits
Create the PostgreSQL tables from the SQL script located inside the ddl-scripts at the root of the project:
```
docker exec -i postgres-db psql -U shopping-cart -t < ddl-scripts/create_tables.sql
```
It creates all tables needed for Akka Persistence as well as the offset store table for Akka Projection.

Configuration for local development

The template contains configuration files for local development. We will be using them in the procedures that follow, but this section provides an overview.

By default, when using sbt run mvn exec:exec the Main class will start an ActorSystem with application.conf which is the configuration intended to be used in production. When running multiple nodes of a Microservice on the same machine, each process (i.e. node) must use unique Akka port numbers.

To simplify the process of running multiple nodes locally, we’ve provided three configuration files named local1.conf, local2.conf, and local3.conf with the port values shown below. All the local configuration files include application.conf.

You can override the configuration by passing one of the provided local configuration files to the build tool using a -D option.

For example, once a piece of functionality is complete, you can run one Akka Cluster node with local1.conf as follows:

# make sure to compile before running exec:exec
mvn compile exec:exec -DAPP_CONFIG=local1.conf

sbt -Dconfig.resource=local1.conf run

Then, on separate terminal windows, you can start two additional nodes with local2.conf and local3.conf:

# On a second terminal run:
#   (make sure to compile before running exec:exec)
mvn compile exec:exec -DAPP_CONFIG=local2.conf

# On a third terminal run:
mvn compile exec:exec -DAPP_CONFIG=local3.conf

# On a second terminal run:
sbt -Dconfig.resource=local2.conf run


# On a third terminal run:
sbt -Dconfig.resource=local3.conf run

The local configuration files set the following ports for each of the example services:

Table 1. shopping-cart-service ports
Node	Akka Cluster	Akka Management HTTP	Akka gRPC
local1.conf	2551	9101	8101
local2.conf	2552	9102	8102
local3.conf	2553	9103	8103

Table 2. shopping-analytics-service ports
Node	Akka Cluster	Akka Management HTTP	Akka gRPC
local1.conf	3551	9201	-
local2.conf	3552	9202	-
local3.conf	3553	9203	-

Table 3. shopping-order-service ports
Node	Akka Cluster	Akka Management HTTP	Akka gRPC
local1.conf	4551	9301	8301
local2.conf	4552	9302	8302
local3.conf	4553	9303	8303