The Haystack REST API documentation along with Ops and Authentication can be found herefound here under the HTTP API section.
Note: In order to use the eval op, you must enable the “Allow get with side effects” setting in your Host → Settings under the API section.
You can try end point: http://host/api/<projName>/read?filter=<axon filter> filter>
Example to read about: http://host/api/<projName>/about
Example to read all operations allowed: http://host/api/<projName>/ops
Example to read all points in the database: http://host/api/<projName>/read?filter=point
Example to read all alarms in the database: http://host/api/<projName>/eval?expr=readAll(equip or point).alarms(today)