Improves documentation

 * Describes better available source tree sharing method (between
xds-agent and xds-server), and which to prefer depending on the
deployment setup.
 * Gives indication about how to pass RSYNC_TARGET and RSYNC_PREFIX
 env vars to the helloworld-native-application build process.
 * Swap chapter order (build before config)

Change-Id: Ie4c22f277a59b0405744d71b0fadff67c5d5d025
Signed-off-by: Johann CAHIER <johann.cahier@iot.bzh>

1 files changed, 14 insertions, 3 deletions

diff --git a/docs/part-1/4-1_build-first-app-setup.md b/docs/part-1/4-1_build-first-app-setup.md
index 1458e4e..7b8fff2 100644
--- a/docs/part-1/4-1_build-first-app-setup.md
+++ b/docs/part-1/4-1_build-first-app-setup.md
@@ -1,12 +1,23 @@
 # Setup
 
+## Sources Sharing Methods
+
+### What are possible ways to share source trees ?
+
 Let's use _helloworld-native-application_ project as example, so you need first to clone
 this project into a directory that will be accessible by `xds-server`.
 
-Depending of the project sharing method:
+There are two possible methods to share sources between your host and the XDS server:
+- Cloud sync: implies your local directory will be sent to and replicated on the server. This method lets you clone project anywhere on your local disk,
+- Path mapping: apply when the xds-server is running locally. This method uses a volume shared between your host and the server, typically `$HOME/xds-workspace` directory. It is much more efficient as there is no replication onto the server ; but you must clone project under the shared directory (`$HOME/xds-workspace` is a good choice because it is shared by default. To create more shared volumes, See --volume option of [container creation script](http://docs.automotivelinux.org/docs/devguides/en/dev/reference/xds/part-1/1-1_install-xds-server-docker.html#create-and-start-a-new-container) )
+
+### Which one should I choose ?
+
+It depends on your [deployment setup](http://docs.automotivelinux.org/docs/devguides/en/dev/reference/xds/part-1/0_Abstract.html) (Standalone, On-Premise or SaaS).
 
-- Cloud sync: you can clone project anywhere on your local disk,
-- Path mapping: you must clone project into `$HOME/xds-workspace` directory.
+* Standalone : use local path mapping. It makes no sense to use cloud sync as it would add pointless overhead.
+* On-Premise : use Clound Sync.
+* SaaS : use Cloud Sync. This is the only way to achieve source sharing in this deployment setup.
 
 <!-- section-note -->
 **Note:** : [helloworld-native-application](https://github.com/iotbzh/helloworld-native-application) project is an AGL