Forest Sample CAP project

This sample project demonstrate how to use a data layer containing geospatial data types with CAP to provide:

• access through odata
• read and write access with transactional consistency
• business logic orchestration:
  • geo coding of addresses when new records are inserted
  • functional validation such as distance to power line or compliance with wildlife sanctuary locations and seasons.

Next Steps

git clone https://github.com/remi-sap/cap-forest.git cd cap-forest

If you're not already logged, cf login

cds deploy

cds watch

Then open the samples folder.

Open add_warehouse.http and click on "Send request"

Open harvesting_block.http and click on "Send request"

How does it all work ?

Data layer

Tables are defined using CAP CDS, for instance:

entity Warehouse {
  key ID   :   Integer;
  label    :   String(111) not null;
  surface  :   Integer;
  address  :   String(300) not null;

  //The fields below will be filled automatically if a valid address is provided
  geo_score:   Double;
  geo_point :  hana.ST_POINT;
  geo_city:    String(200);
  geo_county:  String(200);
  geo_country_iso3:  String(3);
}

The geocoding process assigns values to the last 5 columns.

CAP extensions

Tables are exposed as odata using srv/Forest.cds. However, we need to make some customizations.

CAP & odata don't fully support geospatial data types, so we need the odata module to ignore them and we'll handle the conversions ourselves. The file .cdsrc.json contains this configuration:

{"odata": { "asProvided": true } }

Define javascript extensions

The odata service definition file srv/Forest.cds has a javascript sibling srv/Forest.js that contains various code blocks:

• conversion between geospatial formats (binary, geojson, well known text)
• call to geocoding function
• functional validation of harvesting blocks. This is done by executing checks in parallel and returning OK when they all succeed.