To enable linden Http API, you need set admin.port in linden properties, see Linden Properties Document.
Index is a POST API.
URL: http://$IP:$Port/index
where $IP is one linden instance IP and $Port is admin.port configured.
Only one parameter is content, Content is an index request in JSON string format. It contains a “type" field to indicate the operation type, whose value may be index, delete, replace, delete_index or swap_index. Please see Linden Work Mode Document for detail.
Search is a GET API.
URL: http://$IP:$Port/search?bql=$BQL
where $BQL is search request, see more in BQL Document. Remember to do URL encoding.
Delete is a POST API.
URL: http://$IP:$Port/delete
Only one parameter is bql, which value is a BQL indicating a delete operation.
A simple Http API demo is in com.xiaomi.linden.demo.cars.HttpAPIDemo in demo module.