Lunch Place Voting System

A system helping in finding a consensus for choosing a place to have lunch in.

Runs in Kalix and scales horizontally.

Each entity instance (area, voter and occasion) can run on a separate hardware so in theory the solution's scalability is unlimited.

Secured by JWT.

Solution is Addressing the Following Problems

• Lunch occasion participants don't have a tool to find consensus while finding a lunch place
• Lunch occasion participants can't remember all lunch place options
• Different personalities may make the verbal at-time-voting unequal

Ubiquitous Language

Prerequisite

• Docker & Docker Compose
• Java 11 or later
• sbt
• grpcui (nice to have)

See more: https://docs.kalix.io/java/index.html#_prerequisites

Run

Open three terminals and run each command in project root in own tabs in given order.

docker-compose up
sbt run
grpcui -plaintext localhost:9000

JWT

JWT as a Bearer token is required:

• User Authorization header in request metadata with JWT token as a value with Bearer -prefix.

Required claims:

• username (admin has admin rights by default)
• organization (each organization is a tenant)

Example:

gRPC UI:

jwt.io

The Flow

1. As Admin (Username admin)
   1. Introduce Area -> Like jyväskylä
   2. Introduce Voter(s) -> Like simo, seppo
2. As Voter (simo)
   1. Introduce Place(s) -> Like fitwok, basecamp, shalimar, nom
   2. Publish Occasion -> Datetimed lunch occasion
   3. Vote a Place For the Occasion
3. As Voter 2 (seppo)
   1. Get Occasions
   2. Get Place IDs
   3. Vote a Place For the Occasion
4. See voting results
   1. Get Occasions

Known Issues

1. AreasWithVotersJoinView LEFT JOIN does not seem to work properly -> Can't see area before it has it's first voter

Creation Process

EventStorming and DDD influenced this process.

Process was iterative despite it has been described as a flow.

1. Identify the problems

2. Define the most important domain event in the system

3. Create mental model for the terminology

4. Define the rest of the domain events

5. Create aggregates and read models

6. Data model

• /src/main/proto/components

7. Business logic

• /src/main/scala/fi/simoroikonen/lunchvote/components

8. Views (read models)

• /src/main/proto/components/area/view
• /src/main/proto/components/occasion/view
• /src/main/proto/components/voter/view
• /src/main/proto/view

9. gRPC API by user (voter & admin)

• /src/main/proto/controller