emily-jiang/qcon-12factor-app-a

QCon 12 FactorApp microservice a

MicroProfile generated Application

Introduction

MicroProfile Starter has generated this MicroProfile application for you.

The generation of the executable jar file can be performed by issuing the following command

mvn clean package

This will create an executable jar file liberty.jar within the target maven folder. This can be started by executing the following command

java -jar target/liberty.jar

Liberty Dev Mode

During development, you can use Liberty's development mode (dev mode) to code while observing and testing your changes on the fly. With the dev mode, you can code along and watch the change reflected in the running server right away; unit and integration tests are run on pressing Enter in the command terminal; you can attach a debugger to the running server at any time to step through your code.

mvn liberty:dev

To launch the test page, open your browser at the following URL

http://localhost:9080/index.html

Specification examples

By default, there is always the creation of a JAX-RS application class to define the path on which the JAX-RS endpoints are available.

Also, a simple Hello world endpoint is created, have a look at the class HelloController.

More information on MicroProfile can be found here

Config

Configuration of your application parameters. Specification here

The example class ConfigTestController shows you how to inject a configuration parameter and how you can retrieve it programmatically.

Fault tolerance

Add resilient features to your applications like TimeOut, RetryPolicy, Fallback, bulkhead and circuit breaker. Specification here

The example class ResilienceController has an example of a FallBack mechanism where an fallback result is returned when the execution takes too long.

Health

The health status can be used to determine if the 'computing node' needs to be discarded/restarted or not. Specification here

The class ServiceHealthCheck contains an example of a custom check which can be integrated to health status checks of the instance. The index page contains a link to the status data.

Metrics

The Metrics exports Telemetric data in a uniform way of system and custom resources. Specification here

The example class MetricController contains an example how you can measure the execution time of a request. The index page also contains a link to the metric page (with all metric info)

JWT Auth

Using the OpenId Connect JWT token to pass authentication and authorization information to the JAX-RS endpoint. Specification here

Have a look at the TestSecureController class which calls the protected endpoint on the secondary application. The ProtectedController (secondary application) contains the protected endpoint since it contains the @RolesAllowed annotation on the JAX-RS endpoint method.

The TestSecureController code creates a JWT based on the private key found within the resource directory. However, any method to send a REST request with an appropriate header will work of course. Please feel free to change this code to your needs.

Open API

Exposes the information about your endpoints in the format of the OpenAPI v3 specification. Specification here

The index page contains a link to the OpenAPI information of your endpoints.

Open Tracing

Allow the participation in distributed tracing of your requests through various micro services. Specification here

Example needs to be created.

Rest Client

A type safe invocation of HTTP rest endpoints. Specification here

The example calls one endpoint from another JAX-RS resource where generated Rest Client is injected as CDI bean.