Reuse demo

PREP

On main screen:

• fullscreen browser. run projects with npm run dev as the ports are already set
  • http-server on the reuse-demo folder, list of links on port 8080
  • tab 1: addresses on port 4006
  • tab 2: base on port 4005
  • tab 3: extension on port 4004
• fullscreen VSCode in reuse-demo folder

For prezzo

Intro

• Introduction of Tanveer and Jorg. Mention COVID

• Explain why we're looking at reuse

  • In a complex app, reuse is better than reinventing the wheel
  • Reuse can be a method to separate code

Demo time

DEMO

• show app running on port 4006 to show list of addresses
• show app running on port 4005 to show list of orders and customers
• show app running on port 4004 that has added fields and customer addresses

Explanation of reuse concepts

• Extend and use a DB entity
• Extend and use a service entity
• How to use and connect to another service
• How to reuse a screen

Explanation of how to package a service and do the imports

• creating and importing the npm package, importing EDMX file

DEMO

npm pack ./dalrae.cap.reuse.base
mkdir extend_demo
cd extend_demo && cds init
cp ../reuse-base-1.0.0.tgz .
pnpm add ./reuse-base-1.0.0.tgz
cds import ../ADDRESSES.edmx

What works and doesn't work, what questions did we ask ourselves

• Deployment

  • Every CAP application creates its own schema when deploying to CF.
  • They don't share data so they so common data is best fetched through another service like search helps
  • open question: multitenancy
  • It also means that any changes and deployments made to the base application do not affect the extended application. npm package is just a snapshot in time

• Versioning

  • we've used npm pack, can also use npmjs or host your own
  • The NPM package takes its version from package.json, mta uses mta.yml package version and deployed version can misalign
    • DEMO Show a a few packs
  • having multiple apps with multiple versions of the base will make for a complicated landscape
  • changes to imported services are immediate and the extensions should be considered before changing them

• Security can be overwritten

  • Pondered on this as a means to provide context or security consious services or entities
  • security annotations can be set on a database entity
  • like all annotations it can be replaced in the extending service
  • open question: reusing security roles, are they deployed too? Locally, mock auth had to be re-entered in the .csdrc file

• External services

  • Try not to mix V4 and V2 services. While it can be done, there are incompatibilities mainly in date notations
  • You can use an external service in the same manner without importing the EDMX. You only need to do the import if you want to use the other service's entities
  • External service entities can be used in draft?