# Type of Information
First, let's ask the RIPE Atlas API for a measurement:
# Metadata
A Measurement object holds information about the measurement itself. First it holds the fields id and the type that, together, provide a unique identifier for the measurement object. Examples of measurement types are HTTP and Traceroute.
The participation requests array holds a list of participation request objects, which describe the probe selection criteria that were made for this measurement. You can read more about the participation request object here.
Please note that this is not the same as the actual probes that are appointed to a measurement by RIPE Atlas. The latter would be part of the status information of the measurement in a object called probes. See below.
Finally, there are some fields that describe some of the measurement's general properties. They are is_public and result, a URL that points to the result of the measurements as performed by the selected probes.
# The Measurement Specification
The Measurement object holds the measurement's settings, called the "measurement specification" in RIPE Atlas terminology. This specification is a mixture of base attributes, available for all types of measurements and type-specific attributes. Examples of such attributes are packets, method or interval.
The measurement specification is the object that is sent to a specific probe to perform its measurement.
You can see an exhaustive list of all measurement specification attributes for all kinds of measurements here.
# Status Information
A Measurement object also holds the information about the time series of measurements to be performed by the probes, like the start and stop time of the measurements and the link to the streaming API resource that holds the result of the performed measurements.
A Measurement object also holds information about the status of the measurement, e.g. if it is currently running, stopped, etc.
Finally, the Measurement object holds information about the actual probes used in the measurement. This information is in an object called probes. This is an optional field, which can be enabled by using the optional_fields=probes query parameter.