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From "ASF GitHub Bot (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (NIFI-2735) Add processor to perform simple aggregations
Date Wed, 07 Sep 2016 12:27:20 GMT

    [ https://issues.apache.org/jira/browse/NIFI-2735?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15470471#comment-15470471
] 

ASF GitHub Bot commented on NIFI-2735:
--------------------------------------

Github user mattyb149 commented on a diff in the pull request:

    https://github.com/apache/nifi/pull/988#discussion_r77811419
  
    --- Diff: nifi-nar-bundles/nifi-standard-bundle/nifi-standard-processors/src/main/java/org/apache/nifi/processors/standard/AggregateValues.java
---
    @@ -0,0 +1,580 @@
    +/*
    + * Licensed to the Apache Software Foundation (ASF) under one or more
    + * contributor license agreements.  See the NOTICE file distributed with
    + * this work for additional information regarding copyright ownership.
    + * The ASF licenses this file to You under the Apache License, Version 2.0
    + * (the "License"); you may not use this file except in compliance with
    + * the License.  You may obtain a copy of the License at
    + *
    + *     http://www.apache.org/licenses/LICENSE-2.0
    + *
    + * Unless required by applicable law or agreed to in writing, software
    + * distributed under the License is distributed on an "AS IS" BASIS,
    + * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    + * See the License for the specific language governing permissions and
    + * limitations under the License.
    + */
    +package org.apache.nifi.processors.standard;
    +
    +import com.jayway.jsonpath.Configuration;
    +import com.jayway.jsonpath.DocumentContext;
    +import com.jayway.jsonpath.InvalidJsonException;
    +import com.jayway.jsonpath.JsonPath;
    +import com.jayway.jsonpath.PathNotFoundException;
    +import com.jayway.jsonpath.spi.json.JacksonJsonProvider;
    +import net.sf.saxon.lib.NamespaceConstant;
    +import net.sf.saxon.xpath.XPathEvaluator;
    +import org.apache.commons.lang3.StringUtils;
    +import org.apache.nifi.annotation.behavior.EventDriven;
    +import org.apache.nifi.annotation.behavior.InputRequirement;
    +import org.apache.nifi.annotation.behavior.ReadsAttribute;
    +import org.apache.nifi.annotation.behavior.ReadsAttributes;
    +import org.apache.nifi.annotation.behavior.SideEffectFree;
    +import org.apache.nifi.annotation.behavior.Stateful;
    +import org.apache.nifi.annotation.behavior.SupportsBatching;
    +import org.apache.nifi.annotation.behavior.WritesAttribute;
    +import org.apache.nifi.annotation.behavior.WritesAttributes;
    +import org.apache.nifi.annotation.documentation.CapabilityDescription;
    +import org.apache.nifi.annotation.documentation.SeeAlso;
    +import org.apache.nifi.annotation.documentation.Tags;
    +import org.apache.nifi.annotation.lifecycle.OnScheduled;
    +import org.apache.nifi.components.PropertyDescriptor;
    +import org.apache.nifi.components.state.Scope;
    +import org.apache.nifi.components.state.StateManager;
    +import org.apache.nifi.components.state.StateMap;
    +import org.apache.nifi.flowfile.FlowFile;
    +import org.apache.nifi.flowfile.attributes.CoreAttributes;
    +import org.apache.nifi.logging.ComponentLog;
    +import org.apache.nifi.processor.AbstractSessionFactoryProcessor;
    +import org.apache.nifi.processor.ProcessContext;
    +import org.apache.nifi.processor.ProcessSession;
    +import org.apache.nifi.processor.ProcessSessionFactory;
    +import org.apache.nifi.processor.ProcessorInitializationContext;
    +import org.apache.nifi.processor.Relationship;
    +import org.apache.nifi.processor.exception.ProcessException;
    +import org.apache.nifi.processor.util.StandardValidators;
    +import org.apache.nifi.stream.io.BufferedInputStream;
    +import org.xml.sax.InputSource;
    +
    +import javax.xml.transform.Source;
    +import javax.xml.xpath.XPathConstants;
    +import javax.xml.xpath.XPathExpression;
    +import javax.xml.xpath.XPathExpressionException;
    +import javax.xml.xpath.XPathFactory;
    +import javax.xml.xpath.XPathFactoryConfigurationException;
    +import java.io.BufferedReader;
    +import java.io.IOException;
    +import java.io.InputStream;
    +import java.io.InputStreamReader;
    +import java.util.ArrayList;
    +import java.util.Collections;
    +import java.util.HashMap;
    +import java.util.HashSet;
    +import java.util.List;
    +import java.util.Map;
    +import java.util.Set;
    +import java.util.concurrent.atomic.AtomicReference;
    +
    +import static javax.xml.xpath.XPathConstants.NODESET;
    +
    +/**
    + * A processor to intermediateAggregate values from incoming flow files. The flow files
are expected to have certain attributes set to allow for
    + * aggregations over a batch of flow files.
    + */
    +@EventDriven
    +@SideEffectFree
    +@SupportsBatching
    +@Tags({"json", "xml", "csv", "aggregate"})
    +@SeeAlso({SplitText.class, SplitJson.class, SplitXml.class})
    +@InputRequirement(InputRequirement.Requirement.INPUT_REQUIRED)
    +@CapabilityDescription("Aggregates values from incoming flow files based on a path to
the desired field and an aggregation operation (SUM, AVG, etc.). "
    +        + "The flow files are expected to have mime.type, fragment.count, fragment.identifier
and fragment.index attributes set, in order for the processor to determine "
    +        + "when a fragment/batch is complete. Supported MIME types include text/csv,
text/plain, application/json, and application/xml. For text/csv and text/plain types, "
    +        + "the flow file is expected to contain a single row of comma-delimited data
(no headers). SplitText can be used for this purpose. For JSON files, SplitJson can be "
    +        + "used to split the document (setting the expected attributes, etc.). For XML
files, SplitXml can be used in a similar manner."
    +        + "Note that all flow files with the same identifier must be routed to this processor,
otherwise the count will need "
    +        + "need to be decremented for each flow file in order to represent the number
of flow files with the same identifier that will be routed to this processor. "
    +        + "Once all fragments with the same identifier have been processed, a flow file
will be transferred to the 'aggregate' relationship containing an attribute with the "
    +        + "aggregated value")
    +@Stateful(scopes = Scope.LOCAL, description = "The processor will temporarily keep state
information for each fragment.identifier, including the current intermediateAggregate "
    --- End diff --
    
    This should be CLUSTER scope, will change.


> Add processor to perform simple aggregations
> --------------------------------------------
>
>                 Key: NIFI-2735
>                 URL: https://issues.apache.org/jira/browse/NIFI-2735
>             Project: Apache NiFi
>          Issue Type: New Feature
>          Components: Extensions
>            Reporter: Matt Burgess
>            Assignee: Matt Burgess
>
> This is a proposal for a new processor (AggregateValues, for example) that can perform
simple aggregation operations such as count, sum, average, min, max, and concatenate, over
a set of "related" flow files. For example, when a JSON file is split on an array (using the
SplitJson processor), the total count of the splits, the index of each split, and the unique
indentifier (shared by each split) are stored as attributes in each flow file sent to the
"splits" relationship:
> https://nifi.apache.org/docs/nifi-docs/components/org.apache.nifi.processors.standard.SplitJson/index.html
> These attributes are the "fragment.*" attributes in the documentation for SplitText,
SplitXml, and SplitJson, for example.
> Such a processor could perform these operations for each flow file split from the original
document, and when all documents from a split have been processed, a flow file could be transferred
to an "aggregate" relationship containing attributes for the operation, aggregate value, etc.
> An interesting application of this (besides the actual aggregation operations) is that
you can use the "aggregate" relationship as an event trigger. For example if you need to wait
until all files from a group are processed, you can use AggregateValues and the "aggregate"
relationship to indicate downstream that the entire group has been processed. If there is
not a Split processor upstream, then the attributes (fragment.*) would have to be manipulated
by the data flow designer, but this can be accomplished with other processors (including the
scripting processors if necessary). 



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