Tutorial: Java enterprise app modernization

Refactoring the Medrec application into microservices

Legacy Java applications are difficult to modernize. Enterprises rely on these monolithic apps to power their businesses but face an urgent mandate to move to the cloud and adopt a cloud native architecture. The following sections track the process of refactoring the MedRec application (also known as the Avitek Medical Records application), a monolithic WebLogic sample Java EE application, into microservices and deploying the new microservices on Oracle Container Engine for Kubernetes (OKE).

Step 1

Learning and assessment

vFunction dynamic analysis observes the actual Medrec business flows and behaviors via a JVM agent then applies static analysis of the bytecode for static dependencies and to assure code coverage. An initial application migration assessment report (see image below) measures application complexity across five dimensions, specifies the set of initial services that vFunction has identified, and related classes, API end points, and exclusivity calculations. The video below introduces the Medrec analysis and discusses several key refactoring concepts including service exclusivity, infrastructure classes, and entry points.

Consolidating services: chat function

As an architect, augmented by the vFunction UI, you have the power to apply your perspective and refinement to the system recommendations. In the Medrec application example, the next step in the process is to begin to further consolidate the services and maximize service exclusivity based on vFunction’s initial decomposition. These next steps show how vFunction takes an architect from an initial service topology to a final, simplified microservice architecture of five services and a common library using best practices including merging services, creating new API endpoints, and building a common services library. The next step involves creating a singular Chat function for the Medrec application. This short video below demonstrates how to merge services, explore dynamic class exclusivity, create new API entry points, and rename a new complete microservice as DrPatientChat which is 100% exclusive.

Constructing a common library

The next video illustrates best practices for ensuring a clean common library by identifying non-foundational classes in the common jar and ways to reduce the scope of a service by ignoring redundant classes that then yield a minimal context.