A flowfile is a basic processing entity in Apache NiFi. It contains data contents and attributes, which are used by NiFi processors to process data. The file content normally contains the data fetched from source systems. The most common attributes of an Apache NiFi FlowFile are −

UUID

This stands for Universally Unique Identifier, which is a unique identity of a flowfile generated by NiFi.

Filename

This attribute contains the filename of that flowfile and it should not contain any directory structure.

File Size

It contains the size of an Apache NiFi FlowFile.

mime.type

It specifies the MIME Type of this FlowFile.

path

This attribute contains the relative path of a file to which a flowfile belongs and does not contain the file name.