CRMS GraphQL API POC

This is a Spring Boot application that uses the GraphQL and GraphiQL Spring Framework Boot Starters. The Spring Boot application internally uses Spring Boot Webflux to make REST calls to external microservices to supply the data.

The GraphQL schema is as follows:

type Query {
    info(uens: [UEN]): [Person]
}

input UEN {
    nric: String
    name: String
    mobile: String
}

enum MhaAddressType {
    APARTMENT_BLK
    WITHOUT_APARTMENT_BLK
    REVERSE_OF_APARTMENT_BLK_STREET_NAME
    OVERSEAS_ADDRESS
    PRIVATE_FLATS_WITH_APARTMENT_BLK
    CO_APARTMENT_BLK
    CO_WITHOUT_APARTMENT_BLK
    QUARTER_ADDRESS
    ISLAND_ADDRESS
    SPACE
}

type MhaAddress {
    type: MhaAddressType
    blockNumber: String
    streetCode: String
    streetName: String
    floor: String
    unit: String
    buildingName: String
    postalCode: String
    newPostalCode: String
}

type Person {
    id: ID!
    nric: String!
    name: String!
    nationalityType: String!
    address: MhaAddress
    allotments: [Allotment]
}

type Allotment {
    id: ID!
    scheme: String!
    subScheme: String!
    year: Int!
    cycle: String!
    amount: Float!
    address: MhaAddress
}

3 resolvers have been defined for the application.

• Root query.
• Person.
• Allotment.

The Person and Allotment resolvers each maps to one REST microservice. If there are additional microservices, we can add more resolvers.

Build

I have specified OpenJDK14 requirement. Maybe unnecessary.

# Compile and package into jar with dependencies
mvn clean package spring-boot:repackage

# Optional: Build Docker image
docker build -t crms-poc .

Run

The application config file is application.yml. It is embedded in the app. By default it listens at port 8090 and contacts the Person and Allotment microservices at http://localhost:8080.

# Run without building jar
mvn spring-boot:run

# Run java jar directly
java -jar target/crms-poc-0.0.1-SNAPSHOT.jar

# Run java jar directly specifying URLs for services
java -jar target/crms-poc-0.0.1-SNAPSHOT.jar --server.port=8081 --services.person.url=http://localhost:8080 --services.allotment.url=http://localhost:8080

# Run Docker image if built
docker run -it --rm -p 8090:8090 crms-poc

Sample Test Run

1. Start servers.

# Run Wei Kang's WireMock Docker image locally in the background
docker run -it --rm -p 8080:8080 cds-mock

# Start app
mvn spring-boot:run

2. Open browser and type http://localhost:8090/graphiql

3. Type in following query.

{
  info(uens: [{nric: "S1111111A"}]) {
    nric
    name
    address {
      blockNumber
      streetCode
      streetName
      floor
      unit
      buildingName
      postalCode
      newPostalCode
    }
    nationalityType
    allotments {
      scheme
      subScheme
      year
      address {
	blockNumber
        streetCode
        streetName
    	floor
      	unit
      	buildingName
      	postalCode
      	newPostalCode
      }
    }
  }
}

To Do

• Current Docker image setup is not usable: the application is not able to communicate to external services easily. The ideal way to do so would be using Docker Compose or Kubernetes.
• Implementation is basic. Lacking more complete and defensive programming practices.
  • No timeout or other more robust approaches to handle problems with REST services.
  • No checking for bad inputs such as invalid NRIC.
  • Error handling is very simple and root errors are not propagated to the caller.
• No unit tests.