CodeLab

Poem API exchange

Codelab

This CodeLab exercise is designed to help you practice RESTful API concepts. We will also practice pair programming and exchanging API endpoints with another team.

So today we will work in pairs of 2 and then exchange our APIs with another team of programmers. This means that you should not create pull-requests to the same repository as you usually do. Instead, each team will have their own repository and then exchange the API endpoints with another team later.

1. The assignment

You are going to build a brilliant API for exchanging poems. The API should be able to handle CRUD operations for poems. Just to get our feet wet with REST APIs and Javalin.

Haiku classic

2. Gather a team of 2 and find another team of 2 to exchange APIs with (later)

Create a team of 3-5 people to work on this exercise. Remember to sign up on Moodle for this exercise. This is mainly for the teachers to be able to check attendance, and for you to get study points.

Pick your favourite style: Haiku, Limerick, Senryu, Tanka, Sonnet, Villanelle, Acrostic, Elegy, Ode, Ghazal, Sestina, Pantoum, Terza Rima, Triolet, Rondel, Rondeau, Villanelle, Ballad, Epic, Free verse, Lyric, Narrative, Prose, Rhymed verse, Blank verse, Concrete, Found, Light, Visual, etc.

5. Get the data ready

Collect 5-10 smashing poems in your favourite style and save them in a text file for later

6. Set up the development environment / start code and Git (one per team)

7. Connect a database and create an Entity + DTO for the poems

Each member should create a database in your docker environment with postgres called poems.
Set up the HibernateConfig file to connect to the database.
Create a Poem entity. You decide which fields you want to have in the Poem entity.
Create a PoemDTO class. The PoemDTO class should have a constructor that takes a Poem entity as a parameter and creates a PoemDTO object from it.

8. Let’s get started

Each team will create a RESTful API for poems. The poems should be stored in a database. Ideally, the API should be able to handle all CRUD operations for poems. But we begin simple with the /poems endpoint. The API should be able to handle the following routes representing a poem resource:

Method	Endpoint	Comment
GET	/poem	Returns all poems from the database
GET	/poem/{id}	Returns a specific poem based on the id
POST	/poem	Creates a new poem
PUT	/poem/{id}	Updates an existing poem
DELETE	/poem/{id}	Deletes an existing poem

When the first endpoint poems (get all poems) is ready, you will try to create a .http file to test the endpoint. The http file should be able to test the endpoint and return the result in a json format.

Exchanging poems with your friends

Now, let’s log into the cphbus hotspot and and find your local IP address. Hand this IP address to your friends ( another team) so they can test your API. We need to be on the same network and subnet to be able to test the API. That’s why we need to log into the same hotspot. So if the other team has IP address 10.132.12.13, Jetty Port 7071, and they have the endpoint /poems, you should be able to test their API by typing http://10.132.12.13:7071/poems in your browser - or from a .http file. NB! If the cphbus hotspot is not available, you may need to use a different network (a phone etc).

9. Build a joint API

The idea is now to share poems with your friends and collect their poems and add them with yours in a new endpoint called /poems/friends. This endpoint should return all poems from your friends’ API and your API together. This will take some fetching, DTO conversion and merging of the two APIs in a joint DTO.

10. Implement all the CRUD operations

Make sure that all CRUD operations are working as expected. You should be able to create, read, update and delete poems from your own API.