eventmonitor

A sample project with ActiveMQ, Spring, WebSockets and Spring Web Services.

Installation

• Download Tomcat 8.5.4
• In Tomcat - add -Dspring.profiles.active=prod to environment variables. Simplest way to do this is to create <tomcat_directory>/bin/setenv.sh file with the following content:

CATALINA_OPTS="-Dspring.profiles.active=prod"
export

• Build the project with:

./gradlew clean build

• Copy eventmonitor.war from build/libs directory to <tomcat_directory>/webapps
• Start Tomcat - execute

./startup.sh

in <tomcat_directory>/bin

• Go to: working application in your browser.

A short overview of the architecture

All requests from clients come to /rest endpoint and are written to the ActiveMQ queue incomingEventQueue where it's processed and saved into other queue - processedEventQueue. Records from this table are written to WebSocket endpoint /server/list.

All the errors also are written to /server/list.

Configuration options

There are 3 configuration files: dev.application.properties (for development environment), test.application.properties (for tests) and prod.application.properties (for production environment).

Database configuration options:

# URL to database server
db.url=jdbc:h2:mem:prod
# DB user name
db.user=sa
# DB password
db.password=

There are several processing configuration options available:

# Should system simulate processing delay. If "false" - event.processingTime.initial and event.processingTime.maxRandom will be ignored
event.processingTime.enableDelay=true
# Constant delay (in ms)
event.processingTime.initial=500
# Max random delay (in ms)
event.processingTime.maxRandom=500

There are several ActiveMQ configuration options available:

# Name of ActiveMQ broker
activemq.broker.name=broker
# URL of ActiveMQ server
activemq.broker.url=tcp://localhost:61616
# Incoming queue name
activemq.queue.name.incomingEventQueue=incomingEventQueue
# Processed (outgoing) queue name
activemq.queue.name.processedEventQueue=processedEventQueue
# Minumum number of ActiveMQ listeners/consumers available
activemq.queue.consumers.count=5
# Maximum number of ActiveMQ listeners/consumers available
activemq.queue.consumers.maxCount=10

Endpoints

There are several endpoints available on the application. HTTP endpoint:

• / or /event-monitor - main entry point for application

REST endpoints:

• /rest/ (PUT method) - send a new event request to the application
• /rest/info (GET method) - version information about the application
• /rest/health-check (GET method) - health check information about the application

Tests

• There is a sample JMeter test available at /etc/jmeter/LoadTest.jmx
• All unit tests are in src/test/.
• Integration test is in src/integration-test directory. This integration test loads Spring application context into embedded Tomcat application server and runs an integration test on it.

Technologies

This project uses the following technologies:

• Java 8
• Spring
• Spring Web Services
• ActiveMQ
• H2 in-memory database
• WebSockets

Note

The project works on Windows, but fails to run on Linux.