Elastic and Cloud-ready Applications

Demo project for presentation about cloud-ready applications with Payara Micro

Build

mvn install

Run

StockWeb service

cd StockWeb
mvn payara-micro:start

After a while, an app is accessible at http://10.31.0.130:8080/ROOT/

StockTicker service

cd StockTicker
mvn payara-micro:start

When it starts, it should be sending data to StockWeb and the browser page should automatically update with data in a graph.

Evolve to Kafka broker

By default, messages are sent over Payara distributed CDI event bus (https://docs.payara.fish/documentation/payara-server/public-api/cdi-events.html)

To switch to Kafka, first start a Kafka broker on localhost:9092 with a topic named "stock". Then modify the following:

• in StockTicker, StockTicker.java, replace @Outbound with @Kafka. This routes messages to KafkaStockPublisher.java
• in StockWeb, StockTickerResource.java, replace @Inbound with @Kafka. The observer method will be getting events from KafkaStockMDB.java
• restart both services

After the switch, the behavior of the application shouldn't change. But it's possible to see messages in the Kafka queue.

Configuration

StockTicker sends fictive stock prices with a symbol (name), by default "Dow Jones". This is specified by a configuration key stockticker.symbol, which is evaluated in StockTicker.java every time when a stock price is generated. The symbol is then displayed above the chart in the web page in StockWeb app.

Modify the symbol displayed in the web page:

• stop StockTicker and only leave StockWeb running (alternatively just start StockWeb)
• set environment variable stockticker_symbol to a value of your custom symbol
• start StockTicker with mvn payara-micro:start

An example for Linux:

cd StockTicker
export stockticker_symbol="My symbol" && mvn payara-micro:start

You can also implement your custom config source to read data from any source. Follow the MicroProfile Config documentation.

You can also try using some built-in config sources in Payara Micro, more info here: https://docs.payara.fish/documentation/microprofile/config.html

A collection of reusable config sources is available at https://www.microprofile-ext.org/.

Metrics

Some standard metrics are available automatically for both services using the /metrics endpoint.

For StockWeb, open http://10.31.0.130:8080/metrics (for JSON output, specify also "application/json" for the "Accept" HTTP header).

Health

For StockWeb, access http://10.31.0.130:8080/health. It gives either

• HTTP 200 if all is OK
• HTTP 503 if the service isn't healthy
• HTTP 500 if service produced an internal error