1-3: The processors that use a DMC client use the DMC in a very specific manner, so they CRUD cache entries as it applies to their operations. There isn't currently a generic processor that lets you call arbitrary cache API methods, that's what the scripting components are for. 4: We don't have the concept of tables in DMC, only key/value pairs. A table can probably be implemented by namespacing the key, not sure if the processors you're using support custom keys though. 5: The DMC operation in a cluster is very similar to how it works on a local installation, except there is a DMC server created on each node in the cluster. However a DMC client still has to choose a single host:port to connect to, and the individual DMC servers are not coordinated at the cluster, meaning if you update one, the others don't get that update; they are fully separate at the moment. 6: AFAIK there is no best practice as far as choosing a DMC server to connect to, other than choosing one on a node that tends to be available most often. You basically get individual, isolated instances to choose from. We have other DMC server implementations that possibly support High Availability and/or Data Durability, such as HBase- or Redis- backed solutions. However neither of these are included with an Apache NiFi distribution, you'd have to bring your own. ... View more

The sql.args.N.type parameters are actually numeric codes indicating the type, not the string name of the type. So instead of setting sql.args.4.type to "CHAR", set it to "1" instead. The mapping of numbers to types is given here. ... View more

You can use ConvertRecord for this, your JsonRecordSetWriter would have its Output Grouping property set to "One Line Per Object". The individual objects won't be pretty printed in the output as you have above, but it will remove the array braces as well as the comma delimiter, and just output each element of the above array as a JSON object on its own line. ... View more

A couple of notes: 1) There is no close() method on the session, I think you want remove(). 2) In your try block you are creating and transferring updated_flowFile, but you don't transfer or remove flowFile. If you replace close() with remove(), it should fix the "transfer relationship not specified" issue. 3) In your except block, you might need to check for updated_flowFile != None before you remove it. If the exception occurs before the updated_flowFile is created, the remove() might fail. 4) Consider using EvaluateJsonPath to extract the "left" and "top" attributes, then ReplaceText to clear the content. Then your provenance/lineage chain will remain intact. Jython is fairly slow so you may see a performance improvement by using EvaluateJsonPath -> ReplaceText ... View more