Template project

Introduction

This is intended as an introductory walkthrough to Lagom in scala. We will learn:

• How to define an API
• How to implement a service using event sourcing
• How to test a lagom service
• How to stream events asynchronously between services

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Prerequisites

This introduction to Lagom is best suited to developers with some prior experience with Scala.

You will need to have the following installed in order to use this material:

1. JDK 1.8 or higher
2. Intellij Community Edition 2016.3
3. Git
4. SBT
5. The intellij scala plugin
6. A unix compatible shell

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Make Yourself Familiar with Sbt

• Read the first chapters of the Getting Started Guide
• Starting sbt takes you to a interactive session
• Take a look at build.sbt and the other .sbt files for this course
• Change directory to the demo-lagom-checkout directory and start sbt as follows:

$ sbt
man [e] > lagom-checkout-demo > initial-state >

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man

The man command, short for manual, displays the setup instructions (what you are reading now) for the courseware. To view the instructions for the current exercise, use the e option. If you are using an IDE, you can also open up the setup instructions (README.md) file or the current exercises instructions (src/test/resources/README.md) file in your workspace.

// display the setup instructions
man [e] > lagom-checkout-demo > initial-state > man

// display the instructions for the current exercise
man [e] > lagom-checkout-demo > initial-state > man e

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course navigation and testing

Navigation through the courseware is possibile with a few sbt commands. Also, tests are provided to confirm our solution is accurate. It is important to note that the tests make some assumptions about the code, in particular, naming and scope; please adjust your source accordingly. Following are the available navigation commands:

// show the current exercise
man [e] > lagom-checkout-demo > initial-state > showExerciseId
[INFO] Currently at exercise_000_initial_state

// move to the next exercise
man [e] > lagom-checkout-demo > initial-state > nextExercise
[INFO] Moved to exercise_001_basket_service

// move to the previous exercise
man [e] > lagom-checkout-demo > basket_service > prevExercise
[INFO] Moved to exercise_000_initial_state

// Get the answers to the exercise
man [e] > lagom-checkout-demo > basket_service > pullSolution
[INFO] Solution for exercise exercise_010_basket_service pulled successfully

// save the current state of an exercise for later retrieval and study
man [e] > lagom-checkout-demo > initial-state > saveState
[INFO] State for exercise exercise_000_initial_state saved successfully

// List previously saved states
man [e] > lagom-checkout-demo > initial-state > savedStates
[INFO] Saved exercise states are available for the following exercise(s):
        exercise_000_initial_state

// Restore a previously saved exercise state
man [e] > lagom-checkout-demo > initial-state > restoreState exercise_000_initial_state
[INFO] Exercise exercise_000_initial_state restored

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clean

To clean your current exercise, use the clean command from your sbt session. Clean deletes all generated files in the target directory.

man [e] > lagom-checkout-demo > initial-state > clean

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compile

To compile your current exercise, use the compile command from your sbt session. This command compiles the source in the src/main/scala directory.

man [e] > lagom-checkout-demo > initial-state > compile

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reload

To reload sbt, use the reload command from your sbt session. This command reloads the build definitions, build.sbt, project/.scala and project/.sbt files. Reloading is a requirement if you change the build definition files.

man [e] > lagom-checkout-demo > initial-state > reload

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test

To test your current exercise, use the test command from your sbt session. Test compiles and runs all tests for the current exercise. Automated tests are your safeguard and validate whether or not you have completed the exercise successfully and are ready to move on.

man [e] > lagom-checkout-demo > initial-state > test

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