Targets

file-out

This target writes logged entries to a file on disk.

Configuration Options

An example file-out target configuration looks like:

[target.<NAME>]
type = "file-out"
filename = "/tmp/rotonda.log"
sources = "bmp-in"
format = "json"

type (mandatory): This must be set to file-out for this type of target.

filename (mandatory): The destination file on the filesystem to write log entries to. If the file does not exist, it is created. If it exists, it will be overwritten.

sources (mandatory): The source Rotonda unit for this target.

format (mandatory): This is one of json, json-min (JSON with empty values omitted) or csv.

mqtt-out

This target publishes JSON events to an MQTT broker via a TCP connection.

Tip

The MQTT broker is not part of Rotonda, it is a separate service that must be deployed and operated separately to Rotonda.

This target ONLY accepts input data that:

Was received from a configured upstream source unit.
Was emitted by a Roto script output stream via the Log handle.

Currently, emitted entries are non-customizable JSON objects, with different objects for different Log type entries.

Configuration Options

The mqtt-out component can be defined in the Rotonda configuration file, like this:

[target.<NAME>]
type = "mqtt-out"
..

where <NAME> is the name of the component. This must be ‘mqtt’ for now.

type (mandatory): This must be set to mqtt-out for this type of target.

sources (mandatory): An [“array”, “of”, “upstream”, “unit”, “names”] from which data will be received.

destination (mandatory): A “host:port” string specifying the host or IP address of an MQTT broker to connect to. If the “:port” part is omitted the IANA registered MQTT port number [3] 1883 will be used. Note: Only unencrypted TCP connections are supported, i.e. TLS and WS are not supported.

client_id (optional): A unique name to identify the client to the server in order to hold state about the session. If empty the server will use a clean session and assign a random name to the client. Servers are required to support names upto 23 bytes in length but may support more.

Default: “”

qos (optional)

MQTT quality-of-service setting for determining how many times a message can be delivered:

0 (at most once)
1 (at least once)
2 (exactly once)

Higher values require more synchronization with the broker leading to lower throughput but greater reliability/correctness.

Default: 2

queue_size (optional)

The number of messages that can be buffered for delivery to the MQTT broker.

Default: 1000

connect_retry_secs (optional)

The number of seconds to wait before attempting to reconnect to the MQTT broker if the connection is lost.

Default: 60

publish_max_secs (optional)

The number of seconds to wait before timing out an attempt to publish a message to the MQTT broker.

Default: 5

topic_template (optional): A “string” template that will be used to determine the MQTT topic to which events will be published. If present, the “{id}” placeholder will be replaced by the “topic” value in the incoming Record value. When using “{id}” an MQTT client that supports MQTT wildcards can still receive all events by subscribing to ‘rotonda/#’ for example.

Default: “rotonda/{id}”

username (optional): A “string” username for login to the MQTT broker.

password (optional): A “string” password for login to the MQTT broker.

null-out

This target discards everything it receives.

Rotonda requires that there always be at least one target. Using this target allows you to run Rotonda without any output at the east-side of the pipeline.

Configuration Options

The null-out component can be defined in the Rotonda configuration file, like this:

[target.<NAME>]
type = "null-out"
..

where <NAME> is the name of the component, to be referenced in the value of the sources field in a receiving component.

type (mandatory): This must be set to null-out for this type of target.

source (mandatory): The upstream unit from which data will be received.