JSON Ledger API Configuration

The configuration of the JSON Ledger API is similar to the gRPC Ledger API configuration. The corresponding parameter group starts with http-ledger-api.

canton {
  participants {
    participant1 {
      http-ledger-api {
        server {
            address = 0.0.0.0
            port = 10010
            port-file = "./json.port"
            path-prefix = "my-prefix"
        }
        websocket-config {
            http-list-max-elements-limit = 1000,
            http-list-wait-time = 2s,
        }
        daml-definitions-service-enabled = true
      }
    }
  }
}

JSON Ledger API Endpoint

Configure the JSON API endpoint by adding the server parameter group.

• Specify the address to indicate the IP address to listen on.

• Specify the port to indicate the port.

• Specify port-file, if you want the Participant Node to write a text file with the port on which the JSON Ledger API is listening. This is useful as a tool to synchronize the start-up of dependent services, as the Participant Node only writes the file once the JSON Ledger API is fully initialized.

• Specify path-prefix if you want the JSON Ledger API content to be served on a customized path instead of /.

Websockets

The endpoints that result in large data sets (/v2/commands/completions, /v2/state/active-contracts, /v2/updates/flats, and /v2/updates/trees) come in two flavors:

• a websocket capable of returning an arbitrarily long result set in a stream

• a HTTP post request returning a limited list of results

The latter type of requests can be parameterized in the Participant Node’s config.

• Set the http-list-max-elements-limit to specify the maximum number of returned rows.

• Set the http-list-wait-time to specify the number of milliseconds of idle time to wait before sending result This parameter is needed in case of open-ended streams such as completions. JSON Ledger API reads from the gRPC stream, and when there are no new elements for “wait” milliseconds -> the result is sent to the client.

Daml definitions service

You can enable the experimental Daml Definitions Service by setting the daml-definitions-service-enabled parameter to true.