add doc re. Guice, *Wiring & *Module to README

Signed-off-by: Michael Vorburger <mike@vorburger.ch>

diff --git a/README.md b/README.md
index 11afc604ff310636dfb6835e980f374894c1cdb3..7055d4b8610e445ee2d10b21636c8ae24c02169d 100644 (file)
--- a/README.md
+++ b/README.md
@@ -1,6 +1,6 @@
 # opendaylight-simple [![Build Status](https://travis-ci.org/vorburger/opendaylight-simple.svg?branch=master)](https://travis-ci.org/vorburger/opendaylight-simple)
 
-Run a typical OpenDaylight SDN application such as netvirt without requiring the Apache Karaf OSGi runtime container.
+Run a typical OpenDaylight SDN application such as CoE or netvirt without requiring the Apache Karaf OSGi runtime container.
 
 See this [presentation given in 2018.09 at the ODL DDF during ONS Europe in Amsterdam](https://docs.google.com/presentation/d/14TM9oCn0nLo7RJAhAHglXM4P6oTxsVjJBfFE1wl1qJc) for some background.
 
@@ -9,16 +9,18 @@ Current status: Work in progress feasibility study to better evaluate required e
 Related "tech debt" clean up changes that are a result of this investigation
 [are slowly trickling into ODL](https://git.opendaylight.org/gerrit/#/q/topic:simple-dist) (and [web](https://git.opendaylight.org/gerrit/#/q/topic:simple-dist_web)).
 
-The goal of this project is to eventually upstream all work done here into EXISTING OpenDaylight projets, and eventually have 0 code left in this repo.
+The goal of this project is to eventually upstream all work done here into EXISTING OpenDaylight projects, and eventually have 0 code left in this repo.
 We do not anticipate this to become a new ODL (or external) project.
 
+We currently use [Guice](https://github.com/google/guice) as dependency injection (DI) framework, instead the OSGi Blueprint (BP) implementation Apache Aries which is used in Karaf.  This choice was made just because Guide was already used for "Component Tests" in ODL, and [infrautils has some useful related helpers](https://wiki.opendaylight.org/view/BestPractices/Component_Tests).  ODL projects' code is not made to depend on Guice.  We simply re-use declarative DI by `javax.inject` standard `@Singleton` & `@Inject` annotations, which [work for both Blueprint (with the blueprint-maven-plugin)](https://wiki.opendaylight.org/view/BestPractices/DI_Guidelines) as well as Guice.  ODL projects are encouraged to migrate their use of `<bean>`, `<reference>` and `<service>` elements in BP XML to annotations to ease this integration.  When we exceptionally need to "stitch together" objects in a non-trivial fashion (e.g. custom object factories & external configuration), we migrate BP XML logic into simple `*Wiring` classes.  _Wiring_ classes are not Guice specific, but pure plain old simple Java.  We then write small `*Module` classes, which are Guice specific, to tie everything together.
+
 This includes support for custom Karaf CLI Commands, based on the [ch.vorburger.karaf.simple](https://github.com/vorburger/ch.vorburger.karaf.simple) POC.
 
 ## How to use in Dev
 
  One of the main advantages of developing with opendaylight-simple is that you DO NOT NEED TO build a package on the CLI to start it, like we are used to in ODL with Karaf.  It's just simple standalone Java, so you just Run e.g. `GeniusMain` or `OpenFlowPluginWiringTest` & Co. directly in your favourite IDE!
 
- The build (`maven-assembly-plugin`) is supringly slow, and you would typically only use it to package and run in production on a remote server.  Locally, in development, you do not have to leave your IDE anymore.  The running code is, of course, identical - there is no OSGi/Karaf runtime "container" anymore now.
+ The build (`maven-assembly-plugin`) is surprisingly slow, and you would typically only use it to package and run in production on a remote server.  Locally, in development, you do not have to leave your IDE anymore.  The running code is, of course, identical - there is no OSGi/Karaf runtime "container" anymore now.
 
 ## How to use in Prod