Modularity/Extensibility decisions, questions

Modularity

Hybrid approach:

• OpenLMIS "core" composed as a Spring Boot application.
  •  Core modules are created as Spring components.  This is likely the requisition/fulfillment set of services
  • The OpenLMIS application is a composition of these components into a distribution.  The distribution:
    • assembles various components together using standard Spring wiring, using Maven to locate dependencies
• See 

Repositories

• OpenLMIS Organization in GitHub publishes several repositories:
  • openlmis-core-domain
    • One or more modules for reference entities, such as Users, Facilities, etc.
    • Artifacts:  jar file, than can run as a single service
  • openlmis-requisition-core
    • Spring boot application.  Composed of several Spring modules (see openlmis-module-xx)
    • Artifacts:  jar file, that can run as a single service
  • openlmis-requisition-module-xx
    • where xx is requisition, fulfillment, etc.
    • holds core modules that are composed in openlmis-core
    • Artifacts:  jar file for each module
  • openlmis-requisition-module-xx-ui
    • UI components that match the service (pending ref UI strategy)
  • openlmis-reference-distro
    • projects fork or copy this to create the actual application.  Reference distribution produces a set of docker images
      • project could create a monolithic app, too. 
    • Artifacts:  the actual OpenLMIS applications, made up of several docker images, stitched together with Docker Compose and configuration (such as DB connecton details if we're sharing a Postgres image).
      • each Docker image is domain bounded.  E.g. one for Requisition/core, one for Inventory Management, one for core domain (ref data), another for UI, and potentially others for add-on modules
  • Reference UI

Use case:  adding new service -- Informed Push -- as part of Reference Distribution

• Update reference distribution
  • Update docker image configuration to add new docker instance for Informed Push.  Will hold image of the new Spring boot application
• Starting published Spring boot application template, create new Spring boot application.  Write informed push logic here
  • If extensibility is foreseen, instead write informed push as a Spring module  
• UI:  create new UI component (starting from published UI template).  Update reference UI application to include

Use Case:  adding a Strategy to Requisition

Questions/Issues

• Reference UI - how to build, compose
  • Do modules package UI into the same repo as module code, or a separate repo?
  • Still need reference UI solution that pulls together various web components, both "core" and additional modules
• Database!
• What to call these docker image boundaries...Feature?  Vertical?  Service?
• Extending domains, e.g. adding attributes to Facilities
• Upfront cost of creating docker images?  
  • build, deploy, logging, etc.  Also, remember this needs to run on (Windows) laptops.  Minimum hardware requirements?
  • Promotes vertical development amongst different teams