[[watching-meetup-data]]
=== Watching Event Data

If you are indexing event data, such as log messages, network traffic, or a web feed, you can create a watch to email notifications when certain events occur.
For example, if you index a feed of RSPVs for meetup events happening around the world, you can create a watch that alerts you to interesting events.

To index the meetup data, you can use https://www.elastic.co/products/logstash[Logstash] to ingest live data from the Meetup.com streaming API, `http://stream.meetup.com/2/rsvps`.

To ingest this data with Logstash:

. https://www.elastic.co/downloads/logstash[Download Logstash] and unpack the
  archive file.

. Create a Logstash configuration file that uses the {logstash-ref}/plugins-inputs-stdin.html[Logstash standard input] and the {logstash-ref}/plugins-outputs-stdout.html[Logstash standard output] and save it in `logstash-{version}` directory as `livestream.conf`:
+
[source,ruby]
----------------------------------------------------------
input {
  stdin {
    codec => json <1>
  }
}
filter {
  date {
    match => [ "event.time", "UNIX_MS" ]
    target => "event_time"
  }
}
output { <2>
  stdout {
    codec => rubydebug
  }
  elasticsearch {
    hosts => "http://localhost:9200"
    user  => "elastic"
    password  => "changeme"
  }
}

----------------------------------------------------------
<1> The meetup data stream is formatted in JSON.
<2> Index the meetup data into Elasticsearch.

. To start indexing the meetup data, pipe the RSVP stream into Logstash and specify your `livestream.conf` configuration file.
+
[source,she]
----------------------------------------------------------

curl http://stream.meetup.com/2/rsvps | bin/logstash -f livestream.conf 
---------------------------------------------------------

Now that you're indexing the meetup RSVPs, you can set up a watch that lets you know about events you might be interested in. For example, let's create a watch that runs every hour, looks for events that talk about about _Open Source_, and sends an email with information about the events.


To set up the watch:

. Specify how often you want to run the watch by adding a schedule trigger to the watch:
+
[source,js]
--------------------------------------------------
{
  "trigger": {
    "schedule": {
      "interval": "1h"
    }
  },
--------------------------------------------------
. Load data into the watch payload by creating an input that searches the meetup data for events that have _Open Source_ as a topic. You can use aggregations to group the data by city, consolidate references to the same events, and sort the events by date.
+
[source,js]
-------------------------------------------------
"input": {
    "search": {
      "request": {
        "indices": [
          "<logstash-{now-1h}>", <1>
          "<logstash-{now}>"
        ],
        "body": {
          "size": 0,
          "query": {
            "bool": {
              "filter": [
                {
                  "range": {
                    "@timestamp": {
                      "gte": "now-3h"
                    }
                  }
                },
                {
                  "match": {
                    "group.group_topics.topic_name": "Open Source" <2>
                  }
                }
              ]
            }
          },
          "aggs": {
            "group_by_city": {
              "terms": {
                "field": "group.group_city.raw", <3>
                "size": 5
              },
              "aggs": {
                "group_by_event": {
                  "terms": {
                    "field": "event.event_url.raw", <4>
                    "size": 5
                  },
                  "aggs": {
                    "get_latest": {
                      "terms": {
                        "field": "@timestamp", <5>
                        "size": 1,
                        "order": {
                          "_term": "desc"
                        }
                      },
                      "aggs": {
                        "group_by_event_name": {
                          "terms": {
                            "field": "event.event_name.raw" <6>
                          }
                        }
                      }
                    }
                  }
                }
              }
            }
          }
        }
      }
    }
  },
--------------------------------------------------
<1> Elasticsearch Date math is used to select the Logstash indices that contain the meetup data. The second pattern is needed in case the previous hour crosses days. 
<2> Find all of the RSVPs with `Open Source` as a topic.
<3> Group the RSVPs by city.
<4> Consolidate multiple RSVPs for the same event.
<5> Sort the events so the latest events are listed first.
<6> Group the events by name.

. To determine whether or not there are any Open Source events, add a compare condition that checks the watch payload to see if there were any search hits.
[source,js]
--------------------------------------------------
"compare" : { "ctx.payload.hits.total" : { "gt" : 0 }}
--------------------------------------------------
. To send an email when _Open Source_ events are found, add an email action:
[source,js]
--------------------------------------------------
"actions": {  
    "email_me": {
      "throttle_period": "10m",
      "email": {
        "from": "<from:email address>",
        "to": "<to:email address>",
        "subject": "Open Source Events",
        "body": { 
          "html": "Found events matching Open Source: <ul>{{#ctx.payload.aggregations.group_by_city.buckets}}<          li>{{key}} ({{doc_count}})<ul>{{#group_by_event.buckets}}
          <li><a href=\"{{key}}\">{{get_latest.buckets.0.group_by_event_name.buckets.0.key}}</a> 
          ({{doc_count}})</li>{{/group_by_event.buckets}}</ul></li>
          {{/ctx.payload.aggregations.group_by_city.buckets}}</ul>"
        }
      }
    }
  }
---------------------------------------------------

NOTE: To enable Watcher to send emails, you must configure an email account in `elasticsearch.yml`. For more information, see <<configuring-email, Working with Various Email Services>>.


The complete watch looks like this:
[source,js]
--------------------------------------------------
PUT _xpack/watcher/watch/meetup
{
  "trigger": {
    "schedule": {
      "interval": "1h"
    }
  },
  "input": {
    "search": {
      "request": {
        "indices": [
          "<logstash-{now-1h}>",
          "<logstash-{now}>"
        ],
        "body": {
          "size": 0,
          "query": {
            "bool": {
              "filter": [
                {
                  "range": {
                    "@timestamp": {
                      "gte": "now-3h"
                    }
                  }
                },
                {
                  "match": {
                    "group.group_topics.topic_name": "Open Source"
                  }
                }
              ]
            }
          },
          "aggs": {
            "group_by_city": {
              "terms": {
                "field": "group.group_city.raw",
                "size": 5
              },
              "aggs": {
                "group_by_event": {
                  "terms": {
                    "field": "event.event_url.raw",
                    "size": 5
                  },
                  "aggs": {
                    "get_latest": {
                      "terms": {
                        "field": "@timestamp",
                        "size": 1,
                        "order": {
                          "_term": "desc"
                        }
                      },
                      "aggs": {
                        "group_by_event_name": {
                          "terms": {
                            "field": "event.event_name.raw"
                          }
                        }
                      }
                    }
                  }
                }
              }
            }
          }
        }
      }
    }
  },
  "condition": {
    "compare": {
      "ctx.payload.hits.total": {
        "gt": 0
      }
    }
  },
  "actions": {  <1>
    "email_me": {
      "throttle_period": "10m",
      "email": {
        "from": "<username>@<domainname>",  <2>
        "to": "<username@<domainname>",     <3>
        "subject": "Open Source events",
        "body": {                           
          "html": "Found events matching Open Source: <ul>{{#ctx.payload.aggregations.group_by_city.buckets}}<li>{{key}} ({{doc_count}})<ul>{{#group_by_event.buckets}}<li><a href=\"{{key}}\">{{get_latest.buckets.0.group_by_event_name.buckets.0.key}}</a> ({{doc_count}})</li>{{/group_by_event.buckets}}</ul></li>{{/ctx.payload.aggregations.group_by_city.buckets}}</ul>" 
         }
      }
    }
  }
}
--------------------------------------------------
// CONSOLE

<1> The email body can include Mustache templates to reference data in the watch payload. By default,it will be <<email-html-sanitization, sanitized>> to block dangerous content. 
<2> Replace the `from` address with the email address you configured in `elasticsearch.yml`.
<3> Replace the `to` address with your email address to receive notifications.


Now that you've created your watch, you can use the <<watcher-api-execute-watch, `_execute`>> API to run it without waiting for the schedule to trigger execution:

[source,js]
--------------------------------------------------
POST _xpack/watcher/watch/meetup/_execute
--------------------------------------------------
// CONSOLE
// TEST[continued]