001 create a detailed description for the data layer

README.md

@@ -3,6 +3,41 @@
 Purs-Android is an android version of the test application which is concidered as a "Take Home Assignment"
 
 # Requirements
+## Data Layer
+
+### Connection
+- The application must have connection to the internet to retrieve the working hours
+- If no connection, the error should be displayed notifying user that he has no connection to the internet
+- If connection lost during request, the error should be displayed notifying a user that connection to the endpoint failed
+- If there is no connection or the connection is lost while retrieving data from a remote computer, the cached data, if any, should be displayed
+
+### Cache
+- When application successfully retrieved the data from remote that data should be persisted on the device for further usage if needed
+- Every time user opens application the cache should be updated in order to keep data fresh
+
+### Data format
+#### Cloud
+The JSON structure contains location structure so the DTO for **location** should be created with the following fields
+- Location name – _String_
+- List of working days – _Collection_
+
+The **working day** structure should contain the following fields:
+- Day of week – _String_
+- Start local time – _String_
+- End local time  – _String_
+
+#### Cache
+The cached structure should be similar to the cloud. There should be 2 entities: **location** and **working hours**. The location structure should contain location id which can be an integer, and the location name which is the String.
+
+Location
+- `LocationId` – _Int_
+- `LocationName` – _String_
+
+Working hours
+- `WorkDayName` – _String_
+- `StartTime` – _String_
+- `EndTime` – _String_
+- `LocationId` – _Int_ (a foreign key pointing  a location associated with it)
 
 # UI Design