tpalfy commented on a change in pull request #4510: URL: https://github.com/apache/nifi/pull/4510#discussion_r489704001
########## File path: nifi-nar-bundles/nifi-hazelcast-bundle/nifi-hazelcast-services/src/main/resources/org.apache.nifi.hazelcast.services.cachemanager.EmbeddedHazelcastCacheManager/additionalDetails.html ########## @@ -0,0 +1,86 @@ +<!DOCTYPE html> +<html lang="en"> +<!-- + 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. +--> +<head> + <meta charset="utf-8" /> + <title>EmbeddedHazelcastCacheManager</title> + <link rel="stylesheet" href="/nifi-docs/css/component-usage.css" type="text/css" /> +</head> + +<body> +<h2>EmbeddedHazelcastCacheManager</h2> + +<p> + This service starts and manages an embedded Hazelcast instance. The instance needs to listen on a port for + possible clients to join in. The cache manager will not join via this port but directly reaches data using the embedded + server instance. This behaviour comes from Hazelcast and not to be prevented but not used as the embedded manager + is intended to be serve as an internal cache storage. However, be aware: this might make the instance reachable + within the same network and it is possible for clients to join. +</p> + +<p> + The properties the service supports are provided in order to make it possible to run multiple instances of Hazelcast + (whatever if via EmbeddedHazelcastCacheManager or externally) without any interference. If no further instances are in + use, the port number and cluster name are not necessary to be set. +</p> + +<p> + The service supports multiple ways to set up NiFi cluster. This is controlled by the property, named "Hazelcast High + Availability Mode". The following values might be used: +</p> + +<h3>None</h3> + +<p> + This is the default value of the property. Used when sharing data within nodes are not desired. With this value, every + NiFi node in the cluster (if it is clustered) depends on it's local Hazelcast server, which are not connected into a + Hazelcast cluster. As part of this, the capability of the Hazelcast instances to connect with other servers (even outside + the NiFi cluster) is turned off. +</p> + +<h3>Cluster</h3> + +<p> + Can be used only in clustered node. Using this mode will result a single Hazelcast cluster consisting the embedded instances + from all the NiFi nodes created by the local instance of the same controller service. This mode assumes that, all the Hazelcast + servers are listening on the same port, thus having variable port number based on expression will prevent joining properly. +</p> + +<p> + The controller service gathers the necessary host list from NiFi cluster related information when the service is enabled. It is + not a prerequisite for all the node to successfully joined at this point, but the join must be initiated. When the controller + service is enabled at the start of the NiFi instance, the enabling of the service will be prevented until the point the node is + considered as clustered. Review comment: ```suggestion The controller service automatically gathers the host list from the NiFi cluster itself when it is enabled. It is not required for all the nodes to have been successfully joined at this point, but the join must have been initiated. ---This part is hard to understand--->When the controller service is enabled at the start of the NiFi instance, the enabling of the service will be prevented until the node is considered clustered. ``` ---------------------------------------------------------------- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. For queries about this service, please contact Infrastructure at: us...@infra.apache.org
