Daml

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 {
        enabled = true
        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
      }
    }
  }
}

The JSON Ledger API is enabled by default. If you want to disable it, set the enabled field to false.

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, /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.

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