Simple service with JSON API using Hibernate/Spring/SpringMVC without frontend.

Voting system for deciding where to have lunch.

System description:

• 2 types of users: admin and regular users
• Admin can input a restaurant and it's lunch menu of the day (2-5 items usually, just a dish name and price)
• Users can vote on which restaurant they want to have lunch at
• Only one vote counted per user
• If user votes again the same day:
  • If it is before 11:00 we assume that he changed his mind.
  • If it is after 11:00 then it is too late, vote can't be changed
• Each restaurant provides new menu each day.

Explanation of technology choice:

1. Build system
   • Alternatives: Maven, Gradle, ANT, SBT
   • Selected: Gradle
   • Reason: Gradle is declarative build system for Java project, that designed to build not only Java projects, and have many possibilities for change behavior of build process
2. Embedded servlet container
   • Alternatives: Tomcat embedded, Jetty
   • Selected: Jetty
   • Reason: Jetty has less footprint (~ 1.4 MiB, ~ 1.6 MiB with websocket implementation) than Tomcat (~ 2.9 MiB, 3.1 MiB with websocket implementation)
3. JSON library
   • Variants: Jackson, GSON, JSON.simple, JSONP
   • Selected: GSON
   • Reason: In some tests (see 1 and 2) GSON have less or comparable performance than Jackson, but its have very small footprint (~ 200 KiB) than Jackson (1.4 MiB). I decide use Jackson for correctly marshall entity objects with cycles.
4. Database (select only from in-memory pure Java database)
   • Variants: H2, HSQLDB, Apache Derby
   • Selected: H2
   • Reason: H2 database is more active project (HSQLDB released 4 version in last 2 years, Derby released 5 versions in last 2 years, H2 released more than 15 versions in last year) and it have less footprint than Derby.
5. Database migration tool
   • Variants: Flyway, Liquibase
   • Selected: Flyway
   • Reason: Flyway support SQL and Java migrations, that allow to realise any migration what can be needed. Liquibase generate SQL from XML form, but this form very complex. SQL migration is simple and good decision.

Useful gradle commands

1. Run project from console: ./gradlew bootRun
2. Build executable jar: ./gradlew build
3. Make code coverage report: ./gradlew clean build jacocoTestReport

CURL commands example

System after start have some build-in users:

1. login: admin, password: admin, role: admin
2. login: user_1, password: password one, role: user
3. login: user_2, password: password two, role: user

Some good things

1. Query first page of restaurants (default size: 20):

curl -i \
  -H "Accept: application/json" \
  -u "user_1:password one" \
  http://localhost:8080/api/restaurant

1. Query second page of restaurants (size: 1):

curl -i \
  -H "Accept: application/json" \
  -u "user_1:password one" \
  'http://localhost:8080/api/restaurant?size=1&page=1'

1. Query first page of restaurants with filter by name (size: 1):

curl -i \
  -H "Accept: application/json" \
  -u "user_1:password one" \
  'http://localhost:8080/api/restaurant?filter=name;~;heLL'

1. Query first page of restaurants with two filters by name (size: 1):

curl -i \
  -H "Accept: application/json" \
  -u "user_1:password one" \
  'http://localhost:8080/api/restaurant?filter=name;~;heLL&filter=name;~;bar'

1. Query first page of restaurants with complex filter by name:

curl -i \
  -H "Accept: application/json" \
  -u "user_1:password one" \
  -X GET \
  -d '{
    "or": [
      {"field": "name", "operation": "~", "value": "heLL"},
      {"field": "name", "operation": "~", "value": "bar"}
    ]
  }' http://localhost:8080/api/restaurant

1. Get information about one Restaurant by id:

curl -i \
  -H "Accept: application/json" \
  -u "user_1:password one" \
  http://localhost:8080/api/restaurant/78a9353f-7e08-40a6-ad70-af2664a37a36 

1. Create new restaurant with some dishes:

curl -i \
  -H "Content-Type: application/json" \
  -u "admin:admin" \
  -X PUT \
  -d '{"name": "Created from CURL",
    "dishes": [
      {"name": "Curl dish 1", "price": 1}, 
      {"name": "Curl dish 2", "price": 2.5}
    ]
  }' http://localhost:8080/api/restaurant

1. Update restaurant: change only name

curl -i \
  -H "Content-Type: application/json" \
  -u "admin:admin" \
  -X PATCH \
  -d '{"name": "Updated from curl"}' \
  http://localhost:8080/api/restaurant/60d4f411-4cff-4f60-b392-46bed14c5f86
curl -i \
  -H "Accept: application/json" \
  -u "user_1:password one" \
  http://localhost:8080/api/restaurant/60d4f411-4cff-4f60-b392-46bed14c5f86

1. Update restaurant: change one dish price

curl -i \
  -H "Content-Type: application/json" \
  -u "admin:admin" \
  -X PATCH \
  -d '{
    "dishes": [
      {"id": "6b2edfa5-0894-4fca-aed0-511171f650f5", "price": 500}
    ]
  }' \
  http://localhost:8080/api/restaurant/60d4f411-4cff-4f60-b392-46bed14c5f86
curl -i \
  -H "Accept: application/json" \
  -u "user_1:password one" \
  http://localhost:8080/api/restaurant/60d4f411-4cff-4f60-b392-46bed14c5f86

1. Update restaurant: add new dish

curl -i \
  -H "Content-Type: application/json" \
  -u "admin:admin" \
  -X PATCH \
  -d '{
    "dishes": [
      {"name": "New dish", "price": 600}
    ]
  }' \
  http://localhost:8080/api/restaurant/60d4f411-4cff-4f60-b392-46bed14c5f86
curl -i \
  -H "Accept: application/json" \
  -u "user_1:password one" \
  http://localhost:8080/api/restaurant/60d4f411-4cff-4f60-b392-46bed14c5f86

1. Get vote score for current date:

curl -i \
  -H "Accept: application/json" \
  -u "user_1:password one" \
  http://localhost:8080/api/restaurant/vote

1. Get vote score for selected date:

curl -i \
  -H "Accept: application/json" \
  -u "user_1:password one" \
  http://localhost:8080/api/restaurant/vote?date=2015-10-31

1. Vote for restaurant:

curl -i \
  -H "Accept: application/json" \
  -u "user_1:password one" \
  -X POST \
  http://localhost:8080/api/restaurant/60d4f411-4cff-4f60-b392-46bed14c5f86/vote

1. Vote for restaurant at specified dateTime (for test purpose):

curl -i -g \
  -H "Accept: application/json" \
  -u "user_1:password one" \
  -X POST \
  http://localhost:8080/api/restaurant/60d4f411-4cff-4f60-b392-46bed14c5f86/vote?datetime=2015-10-21T10:30:21.000Z[GMT]
curl -i \
  -H "Accept: application/json" \
  -u "user_1:password one" \
  http://localhost:8080/api/restaurant/vote?date=2015-10-21

Some evil things

1. Create restaurant with empty name

curl -i \
  -H "Content-Type: application/json" \
  -u "admin:admin" \
  -X PUT \
  -d '{"name": "",
    "dishes": [
    ]
  }' http://localhost:8080/api/restaurant

1. Add new dish without price to exists restaurant

curl -i \
  -H "Content-Type: application/json" \
  -u "admin:admin" \
  -X PATCH \
  -d '{
    "dishes": [
      {"name": "New dish"}
    ]
  }' \
  http://localhost:8080/api/restaurant/60d4f411-4cff-4f60-b392-46bed14c5f86