# Java Plugin for Detection changes in clustering topology

**URL:** <https://discuss.elastic.co/t/java-plugin-for-detection-changes-in-clustering-topology/94659>\
**Category:** Elasticsearch\
**Created:** [July 26, 2017, 3:31pm UTC](https://discuss.elastic.co/t/java-plugin-for-detection-changes-in-clustering-topology/94659 "2017-07-26T15:31:20Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![Leonardo\_Oporto](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/leonardo_oporto/32/20474_2.png) [@Leonardo\_Oporto](https://discuss.elastic.co/u/Leonardo_Oporto)\
**Post date:** [July 26, 2017, 3:31pm UTC](https://discuss.elastic.co/t/java-plugin-for-detection-changes-in-clustering-topology/94659/1 "2017-07-26T15:31:20Z")

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Hi community!

I am implementing a plugin for ES 2.x using Java and I need to detect when a node joins to the cluster in order to take an action. I understand that this should be related with the use of Discovery class but I am not really sure how,  
from plugin class, create a listener or something that is trigger when a new node arrives..

If somebody has a clue, I would appreciate 🙂  
Thanks  
Leo.

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**Author:** ![system](https://us1.discourse-cdn.com/elastic/original/3X/1/a/1ac57faf039f6b580b3f104ef42a2a89e41014de.png) [@system](https://discuss.elastic.co/u/system)\
**Post date:** [August 23, 2017, 3:31pm UTC](https://discuss.elastic.co/t/java-plugin-for-detection-changes-in-clustering-topology/94659/2 "2017-08-23T15:31:28Z")

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