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https://issues.apache.org/jira/browse/NIFI-329?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16056794#comment-16056794
 ] 

ASF GitHub Bot commented on NIFI-329:
-------------------------------------

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

    https://github.com/apache/nifi/pull/1541#discussion_r123135376
  
    --- Diff: 
nifi-nar-bundles/nifi-irc-bundle/nifi-irc-processors/src/main/java/org/apache/nifi/processors/irc/handlers/ConsumerEventHandler.java
 ---
    @@ -0,0 +1,127 @@
    +/*
    + * 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.irc.handlers;
    +
    +import net.engio.mbassy.listener.Handler;
    +import net.engio.mbassy.listener.Invoke;
    +import org.apache.nifi.flowfile.FlowFile;
    +import org.apache.nifi.logging.ComponentLog;
    +import org.apache.nifi.processor.ProcessContext;
    +import org.apache.nifi.processor.ProcessSession;
    +import org.apache.nifi.processor.ProcessSessionFactory;
    +import org.apache.nifi.processor.exception.FlowFileAccessException;
    +import org.apache.nifi.processor.io.OutputStreamCallback;
    +import org.apache.nifi.processors.irc.ConsumeIRC;
    +import org.apache.nifi.util.StopWatch;
    +import org.kitteh.irc.client.library.event.channel.ChannelMessageEvent;
    +import org.kitteh.irc.client.library.event.helper.MessageEvent;
    +import org.kitteh.irc.client.library.event.user.PrivateMessageEvent;
    +import org.kitteh.irc.client.library.util.Format;
    +
    +import java.io.IOException;
    +import java.io.OutputStream;
    +import java.util.HashMap;
    +import java.util.Map;
    +import java.util.concurrent.TimeUnit;
    +
    +
    +public class ConsumerEventHandler extends EventHandler {
    +
    +    public ConsumerEventHandler(ProcessContext context, 
ProcessSessionFactory sessionFactory, ComponentLog logger) {
    +        super(context, sessionFactory, logger);
    +    }
    +
    +    @Handler(delivery = Invoke.Asynchronously)
    +    protected void onPrivateMessageReceived(PrivateMessageEvent event) {
    +        logger.info("Received private message '{}' from {} while waiting 
for messages on {} ",
    +                new Object[] {event.getMessage(), 
event.getActor().getName(), 
context.getProperty(ConsumeIRC.IRC_CHANNEL).getValue()});
    +        if 
(context.getProperty(ConsumeIRC.IRC_PROCESS_PRIV_MESSAGES).asBoolean()) {
    +            turnEventIntoFlowFile(event);
    +        } else {
    +            event.sendReply(String.format("Hi %s. Thank you for your 
message but I am not looking to chat with strangers.",
    +                    String.valueOf(event.getActor().getNick())));
    +        }
    +    }
    +
    +    @Handler(delivery = Invoke.Asynchronously)
    +    protected void onChannelMessageReceived(ChannelMessageEvent event) {
    +        // verify if the message was sent to the channel the processor is 
consuming
    +        if 
(event.getChannel().getName().equals(context.getProperty(ConsumeIRC.IRC_CHANNEL).getValue()))
 {
    +
    +            logger.info("Received message '{}'  on channel {} while 
waiting for messages on {} ",
    +                    new Object[]{event.getMessage(), 
event.getChannel().getName(), 
context.getProperty(ConsumeIRC.IRC_CHANNEL).getValue()});
    +            turnEventIntoFlowFile(event);
    +        }
    +    }
    +
    +    private void turnEventIntoFlowFile(final MessageEvent messageEvent) {
    --- End diff --
    
    I'm not super familiar with this irc library, but I think that what is 
going on here is a bit "unorthodox". I think that this irc client allows you to 
register callbacks, and when a message arrives, it calls your callback. If I'm 
reading this right this class has stashed away the session that was passed into 
the first onTrigger(), and then used to create new flowfiles OUTSIDE the 
onTrigger method of the processor, which is certainly not the pattern for most 
of the other "GetX" processors I've seen (I've seen: create a queue between the 
service and the processor, and when onTrigger() is called consumes from that 
queue). @joewitt  - do you have any cautionary tales about using ProcessSession 
in this way?


> Provide processor(s) to interact with IRC
> -----------------------------------------
>
>                 Key: NIFI-329
>                 URL: https://issues.apache.org/jira/browse/NIFI-329
>             Project: Apache NiFi
>          Issue Type: Sub-task
>          Components: Examples
>            Reporter: Joseph Witt
>            Assignee: Andre F de Miranda
>            Priority: Minor
>              Labels: beginner
>
> - Processor(s) to interact with IRC (sending/receiving)
> One approach: A single processor which both sends and receives data from a 
> given IRC channel.  The user can configure the IRC host, username, password, 
> channel, etc...  The connection then is held open and the processor will 
> produce an output flow file for every message received in the IRC channel 
> which will have as attributes the message content, sender, time, etc..  That 
> same processor can also read flow files from its queue which contain message 
> text in an attribute.  In this manner the processor can support bidirectional 
> interaction with IRC.
> Would then also be interesting to make it really easy for a user to generate 
> a message via the UI as well as easily to consume a message via the UI.  
> These could be very generic processors/widgets for creation/consumption and 
> good for these sorts of cases.
> There are active IRC channels which are great for demonstration of relatively 
> active datastreams.  Weather updates, Wikipedia updates, etc...



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