[NIFI-8661] Update Record Reader/Writer lookup services to not require specific attributes exist

• Type: Improvement
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 1.14.0
• Component/s: Extensions
• Assignee: Mark Payne
• Reporter: Mark Payne
• Created: 04/Jun/21 18:05
• Updated: 04/Jun/21 20:24
• Resolved: 04/Jun/21 20:22

Description

NIFI-5829 introduced a ReaderLookup service and a RecordSetWriterLookup service. However, these services make the assumption that the reader/writer to use exists on an attribute of the flowfile such as recordreader.name. This means that these services are not applicable for many situations, especially for source processors.

A more convenient way would be to just add a property to these services indicating the name of the service to use, instead of expecting that an attribute with that name exists. We can set the default value of the property to `${recordreader.name}` etc. in order to maintain backward compatibility.

But this gives us the flexibility, for example, to use this in ConsumeKafkaRecord where kafka message headers are available in Expression Language and also gives us the ability to use a parameter for specifying the data format to use.

Issue Links

• links to: GitHub Pull Request #5129