[
https://issues.apache.org/jira/browse/NIFI-1582?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15726306#comment-15726306
]
ASF GitHub Bot commented on NIFI-1582:
--------------------------------------
Github user mattyb149 commented on a diff in the pull request:
https://github.com/apache/nifi/pull/319#discussion_r91141036
--- Diff:
nifi-nar-bundles/nifi-update-attribute-bundle/nifi-update-attribute-processor/src/main/java/org/apache/nifi/processors/attributes/UpdateAttribute.java
---
@@ -162,20 +146,33 @@ public ValidationResult validate(String subject,
String input, ValidationContext
// static properties
public static final PropertyDescriptor DELETE_ATTRIBUTES = new
PropertyDescriptor.Builder()
.name("Delete Attributes Expression")
- .description("Regular expression for attributes to be deleted
from flowfiles.")
+ .description("Regular expression for attributes to be deleted
from FlowFiles.")
.required(false)
.addValidator(DELETE_PROPERTY_VALIDATOR)
.expressionLanguageSupported(true)
.build();
- // relationships
- public static final Relationship REL_SUCCESS = new
Relationship.Builder()
- .description("All FlowFiles are routed to this
relationship").name("success").build();
+ public static final PropertyDescriptor STORE_STATE = new
PropertyDescriptor.Builder()
+ .name("Store State")
+ .description("Select whether or not state will be stored.
Selecting 'Stateless' will offer the default functionality of purely updating
the attributes on a " +
+ "FlowFile in a stateless manner. Selecting 'Stateful'
will not only store the attributes on the FlowFile but also in the Processors
state. See the 'Stateful Usage' " +
+ "topic of the 'Additional Details' section of this
processor's documentation for more information")
+ .required(true)
+ .allowableValues(DO_NOT_STORE_STATE, STORE_STATE_LOCALLY)
+ .defaultValue(DO_NOT_STORE_STATE)
+ .build();
+ public static final PropertyDescriptor STATEFUL_VARIABLES_INIT_VALUE =
new PropertyDescriptor.Builder()
+ .name("Stateful Variables Initial Value")
+ .description("If using state to set/reference variables then
this value is used to set the initial value of the stateful variable. This will
only be used in the @OnScheduled method " +
+ "when state does not contain a value for the
variable.")
+ .required(false)
+ .defaultValue("0")
--- End diff --
Should this be empty rather than zero? Seems like many of the use cases are
numeric in nature so I see the value of a zero default, but wondering for the
most general case if it should default to empty. I'm fine either way, just
wanted your thoughts on it.
> New processor to update attributes with state
> ---------------------------------------------
>
> Key: NIFI-1582
> URL: https://issues.apache.org/jira/browse/NIFI-1582
> Project: Apache NiFi
> Issue Type: New Feature
> Reporter: Joseph Percivall
> Assignee: Joseph Percivall
>
> This idea was sparked by a thread on the user list and should allow basic
> data science:
> I expect that in the future I’ll need something a little more sophisticated
> but for now my problem is very simple:
> I want to be able to trigger an alert (only once) when an attribute in an
> incoming stream, for instance, goes over a predefined threshold. The
> Processor should then trigger (only once again) another trigger when the
> signal goes back to normal (below threshold). Basically a RouteByAttribute
> but with memory.
> Thanks
> Claudio
> ------------------------------------------------
> Hello Claudio,
> Your use-case actually could leverage a couple of recently added features to
> create a really cool open-source processor. The two key features that were
> added are State Management and the ability to reference processor specific
> variables in expression language. You can take a look at RouteText to see
> both in action.
> By utilizing both you can create a processor that is configured with multiple
> Expression language expressions. There would be dynamic properties which
> would accept expression language and then store the evaluated value via state
> management. Then there would be a routing property (that supports expression
> language) that could simply add an attribute to the flowfile with the
> evaluated value which would allow it to be used by flowing processors for
> routing.
> This would allow you to do your use-case where you store the value for the
> incoming stream and route differently once you go over a threshold. It could
> even allow more complex use-cases. One instance, I believe, would be possible
> is to have a running average and standard deviation and route data to
> different locations based on it's standard deviation.
> You can think of this like an UpdateAttribute with the ability to store and
> calculate variables using expression language.
> Joe
--
This message was sent by Atlassian JIRA
(v6.3.4#6332)
