Helidon Quickstart SE - Employee Directory Example

This project implements an employee directory REST service using Helidon SE. The application is composed of a Helidon REST Microservice backend along with an HTML/JavaScript front end. The source for both application is included with the Maven project.

By default, the service uses a ArrayList backend with sample data. You can connect the backend application to an Oracle database by changing the values in the resources/application.yaml file.

The service uses Helidon DB Client to access the database.

Build and run

mvn package
java -jar target/employee-app.jar

Create script

If you do not have the employee table in your database, you can create it and required resources as follows:

CREATE TABLE EMPLOYEE (ID NUMBER(6), 
    FIRSTNAME VARCHAR2(20), 
    LASTNAME VARCHAR2(25), 
    EMAIL VARCHAR2(30), 
    PHONE VARCHAR2(30),
    BIRTHDATE VARCHAR2(15),
    TITLE VARCHAR2(20),
    DEPARTMENT VARCHAR2(20));

ALTER TABLE EMPLOYEE ADD (CONSTRAINT emp_id_pk PRIMARY KEY (ID));

CREATE SEQUENCE EMPLOYEE_SEQ INCREMENT BY 1 NOCACHE NOCYCLE;

Exercise the application

Get all employees.

curl -X GET curl -X GET http://localhost:8080/employees

Only 1 output record is shown for brevity:

[
  {
    "birthDate": "1970-11-28T08:28:48.078Z",
    "department": "Mobility",
    "email": "Hugh.Jast@example.com",
    "firstName": "Hugh",
    "id": "48cf06ad-6ed4-47e6-ac44-3ea9c67cbe2d",
    "lastName": "Jast",
    "phone": "730-715-4446",
    "title": "National Data Strategist"
  }
]

Get all employees whose last name contains "S".

curl -X GET http://localhost:8080/employees/lastname/S

Only 1 output record is shown for brevity:

[
  {
    "birthDate": "1978-03-18T17:00:12.938Z",
    "department": "Security",
    "email": "Zora.Sawayn@example.com",
    "firstName": "Zora",
    "id": "d7b583a2-f068-40d9-aec0-6f87899c5d8a",
    "lastName": "Sawayn",
    "phone": "923-814-0502",
    "title": "Dynamic Marketing Designer"
  }
]

Get an individual record.

curl -X GET http://localhost:8080/employees/48cf06ad-6ed4-47e6-ac44-3ea9c67cbe2d

Output:

[
  {
    "birthDate": "1970-11-28T08:28:48.078Z",
    "department": "Mobility",
    "email": "Hugh.Jast@example.com",
    "firstName": "Hugh",
    "id": "48cf06ad-6ed4-47e6-ac44-3ea9c67cbe2d",
    "lastName": "Jast",
    "phone": "730-715-4446",
    "title": "National Data Strategist"
  }
]

Connect with a web browser at:

http://localhost:8080/public/index.html

Try health and metrics

curl -s -X GET http://localhost:8080/health

{
  "outcome": "UP",
  "checks": [
    {
      "name": "deadlock",
      "state": "UP"
    },
    {
      "name": "diskSpace",
      "state": "UP",
      "data": {
        "free": "306.61 GB",
        "freeBytes": 329225338880,
        "percentFree": "65.84%",
        "total": "465.72 GB",
        "totalBytes": 500068036608
      }
    },
    {
      "name": "heapMemory",
      "state": "UP",
      "data": {
        "free": "239.35 MB",
        "freeBytes": 250980656,
        "max": "4.00 GB",
        "maxBytes": 4294967296,
        "percentFree": "99.59%",
        "total": "256.00 MB",
        "totalBytes": 268435456
      }
    }
  ]
}

Prometheus Format

curl -s -X GET http://localhost:8080/metrics

Only 1 output item is shown for brevity:

# TYPE base:classloader_current_loaded_class_count counter
# HELP base:classloader_current_loaded_class_count Displays the number of classes that are currently loaded in the Java virtual machine.
base:classloader_current_loaded_class_count 3995

JSON Format

curl -H 'Accept: application/json' -X GET http://localhost:8080/metrics

Output:

{
  "base": {
    "classloader.currentLoadedClass.count": 4011,
    "classloader.totalLoadedClass.count": 4011,
    "classloader.totalUnloadedClass.count": 0,
    "cpu.availableProcessors": 8,
    "cpu.systemLoadAverage": 1.65283203125,
    "gc.G1 Old Generation.count": 0,
    "gc.G1 Old Generation.time": 0,
    "gc.G1 Young Generation.count": 2,
    "gc.G1 Young Generation.time": 8,
    "jvm.uptime": 478733,
    "memory.committedHeap": 268435456,
    "memory.maxHeap": 4294967296,
    "memory.usedHeap": 18874368,
    "thread.count": 11,
    "thread.daemon.count": 4,
    "thread.max.count": 11
  },
  "vendor": {
    "grpc.requests.count": 0,
    "grpc.requests.meter": {
      "count": 0,
      "meanRate": 0,
      "oneMinRate": 0,
      "fiveMinRate": 0,
      "fifteenMinRate": 0
    },
    "requests.count": 5,
    "requests.meter": {
      "count": 5,
      "meanRate": 0.01046407983617782,
      "oneMinRate": 0.0023897243038835964,
      "fiveMinRate": 0.003944597070306631,
      "fifteenMinRate": 0.0023808575122958794
    }
  }
}

Build the Docker Image

docker build -t employee-app .

Start the application with Docker

docker run --rm -p 8080:8080 employee-app:latest

Exercise the application as described above.

Deploy the application to Kubernetes

kubectl cluster-info                # Verify which cluster
kubectl get pods                    # Verify connectivity to cluster
kubectl create -f app.yaml   # Deply application
kubectl get service employee-app  # Get service info

Oracle DB Credentials

You can connect to two different datastores for the back end application. Just fill in the application.yaml files. To use an ArrayList as the data store, simply set drivertype to Array. To connect to an Oracle database, you must set all the values: user, password, hosturl, and drivertype. For Oracle, the drivertype should be set to Oracle.

Sample application.yaml

app:
  user: <user-db>
  password: <password-user-db>
  hosturl: <hostname>:<port>/<database_unique_name>.<host_domain_name>
  drivertype: Array

  server:
    port: 8080
    host: 0.0.0.0

Create the database objects

1. Create a connection to your Oracle Database using sqlplus or SQL Developer. See https://docs.cloud.oracle.com/iaas/Content/Database/Tasks/connectingDB.htm.
2. Create the database objects:

CREATE TABLE EMPLOYEE (
      ID INTEGER NOT NULL,
      FIRSTNAME VARCHAR(100),
      LASTNAME VARCHAR(100),
      EMAIL VARCHAR(100),
      PHONE VARCHAR(100),
      BIRTHDATE VARCHAR(10),
      TITLE VARCHAR(100),
      DEPARTMENT VARCHAR(100),
      PRIMARY KEY (ID)
      );

CREATE SEQUENCE EMPLOYEE_SEQ
      START WITH     100
      INCREMENT BY   1;

INSERT INTO EMPLOYEE (ID, FIRSTNAME, LASTNAME, EMAIL, PHONE, BIRTHDATE, TITLE, DEPARTMENT) VALUES (EMPLOYEE_SEQ.nextVal, 'Hugh', 'Jast', 'Hugh.Jast@example.com', '730-555-0100', '1970-11-28', 'National Data Strategist', 'Mobility');

INSERT INTO EMPLOYEE (ID, FIRSTNAME, LASTNAME, EMAIL, PHONE, BIRTHDATE, TITLE, DEPARTMENT) VALUES (EMPLOYEE_SEQ.nextVal, 'Toy', 'Herzog', 'Toy.Herzog@example.com', '769-555-0102', '1961-08-08', 'Dynamic Operations Manager', 'Paradigm');

INSERT INTO EMPLOYEE (ID, FIRSTNAME, LASTNAME, EMAIL, PHONE, BIRTHDATE, TITLE, DEPARTMENT) VALUES (EMPLOYEE_SEQ.nextVal, 'Reed', 'Hahn', 'Reed.Hahn@example.com', '429-555-0153', '1977-02-05', 'Future Directives Facilitator', 'Quality');

INSERT INTO EMPLOYEE (ID, FIRSTNAME, LASTNAME, EMAIL, PHONE, BIRTHDATE, TITLE, DEPARTMENT) VALUES (EMPLOYEE_SEQ.nextVal, 'Novella', 'Bahringer', 'Novella.Bahringer@example.com', '293-596-3547', '1961-07-25', 'Principal Factors Architect', 'Division');

INSERT INTO EMPLOYEE (ID, FIRSTNAME, LASTNAME, EMAIL, PHONE, BIRTHDATE, TITLE, DEPARTMENT) VALUES (EMPLOYEE_SEQ.nextVal, 'Zora', 'Sawayn', 'Zora.Sawayn@example.com', '923-555-0161', '1978-03-18', 'Dynamic Marketing Designer', 'Security');

INSERT INTO EMPLOYEE (ID, FIRSTNAME, LASTNAME, EMAIL, PHONE, BIRTHDATE, TITLE, DEPARTMENT) VALUES (EMPLOYEE_SEQ.nextVal, 'Cordia', 'Willms', 'Cordia.Willms@example.com', '778-555-0187', '1989-03-31', 'Human Division Representative', 'Optimization');