# New Elasticsearch Discovery Plugin **URL:** \ **Category:** Elasticsearch\ **Created:** [May 13, 2014, 1:19pm UTC](https://discuss.elastic.co/t/new-elasticsearch-discovery-plugin/17481 "2014-05-13T13:19:04Z")\ **Posts on this page:** 4\ **Page:** 1
**Author:** ![StarDrek59](https://avatars.discourse-cdn.com/v4/letter/s/c4cdca/32.png) [@StarDrek59](https://discuss.elastic.co/u/StarDrek59)\ **Post date:** [May 13, 2014, 1:19pm UTC](https://discuss.elastic.co/t/new-elasticsearch-discovery-plugin/17481/1 "2014-05-13T13:19:04Z")
I just start using Elasticsearch and analyze its source code. I need to modify its discovery system by registering the nodes on a kind of database. So I suppose that it's easier to develop a plugin instead of modifying the source itself. But after reading some discovery plugins like the basic one Zen disocvery, zookeeper discovery or cloud-aws plugin, I still don't understand some things. 1. How to provide the discovered nodes to the elasticsearch core programm? I think it uses the "DiscoveryNodes" class. 2. I saw that the different discovery classes use different elements for their constructors but where are they defined? 3. I don't understand what the "ClusterState" is after reading the code and why it is useful. 4. I didn't understand what the "AbstractLifecycleComponent" class works. It seems to be like a thread or runnable class but it isn't and just provides "doStart". What is it? 5. Is the publish action from master mandatory? Because, if I use a database, I won't use it. I didn't find enough documentation about the source code so a little help would be great. To implement this discovery plugin, I thought about a thread, which is started be the discovery class, retrieving information from the database periodically. But I don't know where I have to register the new nodes discovered by this thread on the database (in the DiscoveryNodes class?). Thanks for reading. -- You received this message because you are subscribed to the Google Groups "elasticsearch" group. To unsubscribe from this group and stop receiving emails from it, send an email to [elasticsearch+unsubscribe@googlegroups.com](mailto:elasticsearch+unsubscribe@googlegroups.com). To view this discussion on the web visit [https://groups.google.com/d/msgid/elasticsearch/41ec456c-744f-4454-8d47-89e89c7b5a93%40googlegroups.com](https://groups.google.com/d/msgid/elasticsearch/41ec456c-744f-4454-8d47-89e89c7b5a93%40googlegroups.com). For more options, visit [https://groups.google.com/d/optout](https://groups.google.com/d/optout). ---
**Author:** ![jprante](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/jprante/32/44941_2.png) [@jprante](https://discuss.elastic.co/u/jprante)\ **Post date:** [May 13, 2014, 4:36pm UTC](https://discuss.elastic.co/t/new-elasticsearch-discovery-plugin/17481/2 "2014-05-13T16:36:39Z")
1. Yes, discovered nodes are provided by the DiscoveryNode class 2. Can you please be more specific - what discovery class use what constructors? Maybe the answer is in 4. 3. ClusterState keeps the current state of the cluster regarding nodes, indices, mappings, and most important the elected leading node that has the privilege to write the cluster state. The leading node in Elasticsearch is called "master". 4. Elasticsearch uses a customized version of the Guice dependency injection framework. You find an introduction at [GitHub - google/guice: Guice (pronounced 'juice') is a lightweight dependency injection framework for Java 8 and above, brought to you by Google.](https://code.google.com/p/google-guice/wiki/Motivation) 5. Yes, it is mandatory. Otherwise, nodes would not be able to receive cluster state updates. Are you sure you need another database? The ClusterState is already a mini database, the content is written in SMILE encoded JSON to disk. Note, that if you poll information from a remote database, you have to implement failover and recovery if contact to the database is lost. Each node carries a node identifier, so perhaps all you want to do is saving the node identifier in the database (for whatever reason). Jörg On Tue, May 13, 2014 at 3:19 PM, StarDrek59 [stardrek59@gmail.com](mailto:stardrek59@gmail.com) wrote: > I just start using Elasticsearch and analyze its source code. > > I need to modify its discovery system by registering the nodes on a kind > of database. So I suppose that it's easier to develop a plugin instead of > modifying the source itself. > But after reading some discovery plugins like the basic one Zen disocvery, > zookeeper discovery or cloud-aws plugin, I still don't understand some > things. > > 1. How to provide the discovered nodes to the elasticsearch core > programm? I think it uses the "DiscoveryNodes" class. > 2. I saw that the different discovery classes use different elements > for their constructors but where are they defined? > 3. I don't understand what the "ClusterState" is after reading the > code and why it is useful. > 4. I didn't understand what the "AbstractLifecycleComponent" class > works. It seems to be like a thread or runnable class but it isn't and just > provides "doStart". What is it? > 5. Is the publish action from master mandatory? Because, if I use a > database, I won't use it. > > I didn't find enough documentation about the source code so a little help > would be great. > > To implement this discovery plugin, I thought about a thread, which is > started be the discovery class, retrieving information from the database > periodically. But I don't know where I have to register the new nodes > discovered by this thread on the database (in the DiscoveryNodes class?). > > Thanks for reading. > > -- > You received this message because you are subscribed to the Google Groups > "elasticsearch" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [elasticsearch+unsubscribe@googlegroups.com](mailto:elasticsearch+unsubscribe@googlegroups.com). > To view this discussion on the web visit > [https://groups.google.com/d/msgid/elasticsearch/41ec456c-744f-4454-8d47-89e89c7b5a93%40googlegroups.com](https://groups.google.com/d/msgid/elasticsearch/41ec456c-744f-4454-8d47-89e89c7b5a93%40googlegroups.com)[https://groups.google.com/d/msgid/elasticsearch/41ec456c-744f-4454-8d47-89e89c7b5a93%40googlegroups.com?utm\_medium=email&utm\_source=footer](https://groups.google.com/d/msgid/elasticsearch/41ec456c-744f-4454-8d47-89e89c7b5a93%40googlegroups.com?utm_medium=email&utm_source=footer) > . > For more options, visit [https://groups.google.com/d/optout](https://groups.google.com/d/optout). -- You received this message because you are subscribed to the Google Groups "elasticsearch" group. To unsubscribe from this group and stop receiving emails from it, send an email to [elasticsearch+unsubscribe@googlegroups.com](mailto:elasticsearch+unsubscribe@googlegroups.com). To view this discussion on the web visit [https://groups.google.com/d/msgid/elasticsearch/CAKdsXoFaoQndZZm8FkVWdCFDXdg%3Dpvwpi6JBooJMVGy3J-Cv%2BQ%40mail.gmail.com](https://groups.google.com/d/msgid/elasticsearch/CAKdsXoFaoQndZZm8FkVWdCFDXdg%3Dpvwpi6JBooJMVGy3J-Cv%2BQ%40mail.gmail.com). For more options, visit [https://groups.google.com/d/optout](https://groups.google.com/d/optout). ---
**Author:** ![StarDrek59](https://avatars.discourse-cdn.com/v4/letter/s/c4cdca/32.png) [@StarDrek59](https://discuss.elastic.co/u/StarDrek59)\ **Post date:** [May 14, 2014, 7:34am UTC](https://discuss.elastic.co/t/new-elasticsearch-discovery-plugin/17481/3 "2014-05-14T07:34:06Z")
First thanks for replying. I'm working in a distributed environment and some services will use the elasticsearch service. So a kind of database is available to locate the different needed services like elasticsearch. I work on different network so the multicast can't be used. Can the unicast ping discovery provide a discovery in this kind of organization? If not the idea is to replace the ping discovery by accessing my database to get the needed information for the discovery and detect the failure on the different nodes (The database is in charge of the heartbeat of the services and their timeout). In this case the "publish" step is not mandatory for me and will decrease the cmmunication between nodes, which is the goal of this kind of discovery. But I'm afraid that it will have a consequence on the behavior of elasticsearch. To conclude and summarize, to do that kind of discovery, I need to "register" the discovered nodes in the "DiscoveryNodes" class and update the "ClusterState". Is it exact? Another little question (I didn't read yet the documentation you provide) but if I must implement a kind of thread, do I need to make my class inherit from the "AbstractLifeCycleComponent" or can I just use an implementation of the "Runnable" interface of Java? Thanks for help. -- You received this message because you are subscribed to the Google Groups "elasticsearch" group. To unsubscribe from this group and stop receiving emails from it, send an email to [elasticsearch+unsubscribe@googlegroups.com](mailto:elasticsearch+unsubscribe@googlegroups.com). To view this discussion on the web visit [https://groups.google.com/d/msgid/elasticsearch/3dfa3a44-cca8-40b6-8a90-920ca609e470%40googlegroups.com](https://groups.google.com/d/msgid/elasticsearch/3dfa3a44-cca8-40b6-8a90-920ca609e470%40googlegroups.com). For more options, visit [https://groups.google.com/d/optout](https://groups.google.com/d/optout). ---
**Author:** ![system](https://us1.discourse-cdn.com/elastic/original/3X/1/a/1ac57faf039f6b580b3f104ef42a2a89e41014de.png) [@system](https://discuss.elastic.co/u/system)\ **Post date:** [July 6, 2017, 1:29am UTC](https://discuss.elastic.co/t/new-elasticsearch-discovery-plugin/17481/4 "2017-07-06T01:29:32Z")