Bump web to 0.8.4 SNAPSHOT
Project: http://git-wip-us.apache.org/repos/asf/helix/repo Commit: http://git-wip-us.apache.org/repos/asf/helix/commit/e8125e8b Tree: http://git-wip-us.apache.org/repos/asf/helix/tree/e8125e8b Diff: http://git-wip-us.apache.org/repos/asf/helix/diff/e8125e8b Branch: refs/heads/master Commit: e8125e8b97febbbf2e80000d870656d0b05e3814 Parents: 8a32026 Author: Junkai Xue <j...@linkedin.com> Authored: Mon Nov 26 16:54:59 2018 -0800 Committer: Junkai Xue <j...@linkedin.com> Committed: Mon Nov 26 16:54:59 2018 -0800 ---------------------------------------------------------------------- website/0.6.1-incubating/pom.xml | 2 +- website/0.6.2-incubating/pom.xml | 2 +- website/0.6.3/pom.xml | 2 +- website/0.6.4/pom.xml | 2 +- website/0.6.5/pom.xml | 2 +- website/0.6.6/pom.xml | 2 +- website/0.6.7/pom.xml | 2 +- website/0.6.8/pom.xml | 2 +- website/0.6.9/pom.xml | 2 +- website/0.7.0-incubating/pom.xml | 2 +- website/0.7.1/pom.xml | 2 +- website/0.8.0/pom.xml | 2 +- website/0.8.1/pom.xml | 2 +- website/0.8.2/pom.xml | 2 +- website/0.8.3/pom.xml | 51 + website/0.8.3/src/site/apt/privacy-policy.apt | 52 + .../src/site/apt/releasenotes/release-0.8.3.apt | 80 ++ website/0.8.3/src/site/markdown/Building.md | 42 + website/0.8.3/src/site/markdown/Features.md | 313 ++++++ website/0.8.3/src/site/markdown/Metrics.md | 217 +++++ website/0.8.3/src/site/markdown/Quickstart.md | 663 +++++++++++++ website/0.8.3/src/site/markdown/Tutorial.md | 207 ++++ .../0.8.3/src/site/markdown/design_crushed.md | 173 ++++ website/0.8.3/src/site/markdown/index.md | 58 ++ .../src/site/markdown/recipes/lock_manager.md | 236 +++++ .../markdown/recipes/rabbitmq_consumer_group.md | 213 +++++ .../recipes/rsync_replicated_file_store.md | 162 ++++ .../site/markdown/recipes/service_discovery.md | 184 ++++ .../site/markdown/recipes/task_dag_execution.md | 199 ++++ .../0.8.3/src/site/markdown/tutorial_admin.md | 408 ++++++++ .../0.8.3/src/site/markdown/tutorial_agent.md | 169 ++++ .../src/site/markdown/tutorial_controller.md | 153 +++ .../0.8.3/src/site/markdown/tutorial_health.md | 46 + .../src/site/markdown/tutorial_messaging.md | 70 ++ .../src/site/markdown/tutorial_participant.md | 102 ++ .../src/site/markdown/tutorial_propstore.md | 34 + .../src/site/markdown/tutorial_rebalance.md | 181 ++++ .../src/site/markdown/tutorial_rest_service.md | 951 +++++++++++++++++++ .../src/site/markdown/tutorial_spectator.md | 75 ++ .../0.8.3/src/site/markdown/tutorial_state.md | 131 +++ .../site/markdown/tutorial_task_framework.md | 395 ++++++++ .../site/markdown/tutorial_task_throttling.md | 41 + .../src/site/markdown/tutorial_throttling.md | 39 + website/0.8.3/src/site/markdown/tutorial_ui.md | 118 +++ .../markdown/tutorial_user_content_store.md | 67 ++ .../markdown/tutorial_user_def_rebalancer.md | 172 ++++ .../0.8.3/src/site/markdown/tutorial_yaml.md | 102 ++ website/0.8.3/src/site/resources/.htaccess | 20 + .../0.8.3/src/site/resources/JobExample.json | 19 + .../src/site/resources/WorkflowExample.json | 46 + .../resources/css/bootstrap-responsive.min.css | 9 + .../src/site/resources/css/bootstrap.min.css | 9 + website/0.8.3/src/site/resources/download.cgi | 22 + .../src/site/resources/images/PFS-Generic.png | Bin 0 -> 72435 bytes .../site/resources/images/RSYNC_BASED_PFS.png | Bin 0 -> 78007 bytes .../resources/images/TaskFrameworkLayers.png | Bin 0 -> 11622 bytes .../src/site/resources/images/UIScreenshot.png | Bin 0 -> 83460 bytes .../src/site/resources/images/UIScreenshot2.png | Bin 0 -> 121388 bytes .../design/crushed/after-using-crushed.png | Bin 0 -> 9935 bytes .../design/crushed/before-using-crush.png | Bin 0 -> 10286 bytes .../resources/images/design/crushed/classes.png | Bin 0 -> 14742 bytes .../design/crushed/crushed-master-dist.png | Bin 0 -> 18725 bytes .../design/crushed/crushed-partition-dist.png | Bin 0 -> 16630 bytes .../images/design/crushed/cursh-master-dist.png | Bin 0 -> 18036 bytes .../design/crushed/cursh-partition-dist.png | Bin 0 -> 16391 bytes .../example-cluster-master-dist-after.png | Bin 0 -> 12899 bytes .../crushed/example-cluster-master-dist.png | Bin 0 -> 13601 bytes .../crushed/example-cluster-partition-dist.png | Bin 0 -> 13472 bytes .../crushed/example-movement-on-expansion.png | Bin 0 -> 31833 bytes .../design/crushed/node-down-master-move.png | Bin 0 -> 16897 bytes .../design/crushed/node-down-partition-move.png | Bin 0 -> 15982 bytes .../images/design/crushed/performance.png | Bin 0 -> 17532 bytes .../src/site/resources/js/bootstrap.min.js | 6 + .../0.8.3/src/site/resources/js/jquery.min.js | 2 + website/0.8.3/src/site/site.xml | 141 +++ website/0.8.3/src/site/xdoc/download.xml.vm | 226 +++++ website/0.8.3/src/test/conf/testng.xml | 27 + website/pom.xml | 3 +- 78 files changed, 6647 insertions(+), 15 deletions(-) ---------------------------------------------------------------------- http://git-wip-us.apache.org/repos/asf/helix/blob/e8125e8b/website/0.6.1-incubating/pom.xml ---------------------------------------------------------------------- diff --git a/website/0.6.1-incubating/pom.xml b/website/0.6.1-incubating/pom.xml index 181cf3d..1bc6a2e 100644 --- a/website/0.6.1-incubating/pom.xml +++ b/website/0.6.1-incubating/pom.xml @@ -23,7 +23,7 @@ under the License. <parent> <groupId>org.apache.helix</groupId> <artifactId>website</artifactId> - <version>0.8.3-SNAPSHOT</version> + <version>0.8.4-SNAPSHOT</version> </parent> <artifactId>0.6.1-incubating-docs</artifactId> http://git-wip-us.apache.org/repos/asf/helix/blob/e8125e8b/website/0.6.2-incubating/pom.xml ---------------------------------------------------------------------- diff --git a/website/0.6.2-incubating/pom.xml b/website/0.6.2-incubating/pom.xml index 9e5ed63..79c540e 100644 --- a/website/0.6.2-incubating/pom.xml +++ b/website/0.6.2-incubating/pom.xml @@ -23,7 +23,7 @@ under the License. <parent> <groupId>org.apache.helix</groupId> <artifactId>website</artifactId> - <version>0.8.3-SNAPSHOT</version> + <version>0.8.4-SNAPSHOT</version> </parent> <artifactId>0.6.2-incubating-docs</artifactId> http://git-wip-us.apache.org/repos/asf/helix/blob/e8125e8b/website/0.6.3/pom.xml ---------------------------------------------------------------------- diff --git a/website/0.6.3/pom.xml b/website/0.6.3/pom.xml index 7b04851..7959e6d 100644 --- a/website/0.6.3/pom.xml +++ b/website/0.6.3/pom.xml @@ -23,7 +23,7 @@ under the License. <parent> <groupId>org.apache.helix</groupId> <artifactId>website</artifactId> - <version>0.8.3-SNAPSHOT</version> + <version>0.8.4-SNAPSHOT</version> </parent> <artifactId>0.6.3-docs</artifactId> http://git-wip-us.apache.org/repos/asf/helix/blob/e8125e8b/website/0.6.4/pom.xml ---------------------------------------------------------------------- diff --git a/website/0.6.4/pom.xml b/website/0.6.4/pom.xml index 3293246..80dfeb8 100644 --- a/website/0.6.4/pom.xml +++ b/website/0.6.4/pom.xml @@ -23,7 +23,7 @@ under the License. <parent> <groupId>org.apache.helix</groupId> <artifactId>website</artifactId> - <version>0.8.3-SNAPSHOT</version> + <version>0.8.4-SNAPSHOT</version> </parent> <artifactId>0.6.4-docs</artifactId> http://git-wip-us.apache.org/repos/asf/helix/blob/e8125e8b/website/0.6.5/pom.xml ---------------------------------------------------------------------- diff --git a/website/0.6.5/pom.xml b/website/0.6.5/pom.xml index 8a2b621..d1507aa 100644 --- a/website/0.6.5/pom.xml +++ b/website/0.6.5/pom.xml @@ -23,7 +23,7 @@ under the License. <parent> <groupId>org.apache.helix</groupId> <artifactId>website</artifactId> - <version>0.8.3-SNAPSHOT</version> + <version>0.8.4-SNAPSHOT</version> </parent> <artifactId>0.6.5-docs</artifactId> http://git-wip-us.apache.org/repos/asf/helix/blob/e8125e8b/website/0.6.6/pom.xml ---------------------------------------------------------------------- diff --git a/website/0.6.6/pom.xml b/website/0.6.6/pom.xml index 91cb758..25a0790 100644 --- a/website/0.6.6/pom.xml +++ b/website/0.6.6/pom.xml @@ -23,7 +23,7 @@ under the License. <parent> <groupId>org.apache.helix</groupId> <artifactId>website</artifactId> - <version>0.8.3-SNAPSHOT</version> + <version>0.8.4-SNAPSHOT</version> </parent> <artifactId>0.6.6-docs</artifactId> http://git-wip-us.apache.org/repos/asf/helix/blob/e8125e8b/website/0.6.7/pom.xml ---------------------------------------------------------------------- diff --git a/website/0.6.7/pom.xml b/website/0.6.7/pom.xml index 16d0447..c7626da 100644 --- a/website/0.6.7/pom.xml +++ b/website/0.6.7/pom.xml @@ -23,7 +23,7 @@ under the License. <parent> <groupId>org.apache.helix</groupId> <artifactId>website</artifactId> - <version>0.8.3-SNAPSHOT</version> + <version>0.8.4-SNAPSHOT</version> </parent> <artifactId>0.6.7-docs</artifactId> http://git-wip-us.apache.org/repos/asf/helix/blob/e8125e8b/website/0.6.8/pom.xml ---------------------------------------------------------------------- diff --git a/website/0.6.8/pom.xml b/website/0.6.8/pom.xml index b39d6db..a7ddaa4 100644 --- a/website/0.6.8/pom.xml +++ b/website/0.6.8/pom.xml @@ -23,7 +23,7 @@ under the License. <parent> <groupId>org.apache.helix</groupId> <artifactId>website</artifactId> - <version>0.8.3-SNAPSHOT</version> + <version>0.8.4-SNAPSHOT</version> </parent> <artifactId>0.6.8-docs</artifactId> http://git-wip-us.apache.org/repos/asf/helix/blob/e8125e8b/website/0.6.9/pom.xml ---------------------------------------------------------------------- diff --git a/website/0.6.9/pom.xml b/website/0.6.9/pom.xml index 0d4de17..a9f60c0 100644 --- a/website/0.6.9/pom.xml +++ b/website/0.6.9/pom.xml @@ -23,7 +23,7 @@ under the License. <parent> <groupId>org.apache.helix</groupId> <artifactId>website</artifactId> - <version>0.8.3-SNAPSHOT</version> + <version>0.8.4-SNAPSHOT</version> </parent> <artifactId>0.6.9-docs</artifactId> http://git-wip-us.apache.org/repos/asf/helix/blob/e8125e8b/website/0.7.0-incubating/pom.xml ---------------------------------------------------------------------- diff --git a/website/0.7.0-incubating/pom.xml b/website/0.7.0-incubating/pom.xml index 70972f3..af58bcb 100644 --- a/website/0.7.0-incubating/pom.xml +++ b/website/0.7.0-incubating/pom.xml @@ -23,7 +23,7 @@ under the License. <parent> <groupId>org.apache.helix</groupId> <artifactId>website</artifactId> - <version>0.8.3-SNAPSHOT</version> + <version>0.8.4-SNAPSHOT</version> </parent> <artifactId>0.7.0-incubating-docs</artifactId> http://git-wip-us.apache.org/repos/asf/helix/blob/e8125e8b/website/0.7.1/pom.xml ---------------------------------------------------------------------- diff --git a/website/0.7.1/pom.xml b/website/0.7.1/pom.xml index e12ef77..63f3937 100644 --- a/website/0.7.1/pom.xml +++ b/website/0.7.1/pom.xml @@ -23,7 +23,7 @@ under the License. <parent> <groupId>org.apache.helix</groupId> <artifactId>website</artifactId> - <version>0.8.3-SNAPSHOT</version> + <version>0.8.4-SNAPSHOT</version> </parent> <artifactId>0.7.1-docs</artifactId> http://git-wip-us.apache.org/repos/asf/helix/blob/e8125e8b/website/0.8.0/pom.xml ---------------------------------------------------------------------- diff --git a/website/0.8.0/pom.xml b/website/0.8.0/pom.xml index 54e9616..da97212 100644 --- a/website/0.8.0/pom.xml +++ b/website/0.8.0/pom.xml @@ -23,7 +23,7 @@ under the License. <parent> <groupId>org.apache.helix</groupId> <artifactId>website</artifactId> - <version>0.8.3-SNAPSHOT</version> + <version>0.8.4-SNAPSHOT</version> </parent> <artifactId>0.8.0-docs</artifactId> http://git-wip-us.apache.org/repos/asf/helix/blob/e8125e8b/website/0.8.1/pom.xml ---------------------------------------------------------------------- diff --git a/website/0.8.1/pom.xml b/website/0.8.1/pom.xml index a94d96e..dd224ac 100644 --- a/website/0.8.1/pom.xml +++ b/website/0.8.1/pom.xml @@ -23,7 +23,7 @@ under the License. <parent> <groupId>org.apache.helix</groupId> <artifactId>website</artifactId> - <version>0.8.3-SNAPSHOT</version> + <version>0.8.4-SNAPSHOT</version> </parent> <artifactId>0.8.1-docs</artifactId> http://git-wip-us.apache.org/repos/asf/helix/blob/e8125e8b/website/0.8.2/pom.xml ---------------------------------------------------------------------- diff --git a/website/0.8.2/pom.xml b/website/0.8.2/pom.xml index 6c918dc..3a0a894 100644 --- a/website/0.8.2/pom.xml +++ b/website/0.8.2/pom.xml @@ -23,7 +23,7 @@ under the License. <parent> <groupId>org.apache.helix</groupId> <artifactId>website</artifactId> - <version>0.8.3-SNAPSHOT</version> + <version>0.8.4-SNAPSHOT</version> </parent> <artifactId>0.8.2-docs</artifactId> http://git-wip-us.apache.org/repos/asf/helix/blob/e8125e8b/website/0.8.3/pom.xml ---------------------------------------------------------------------- diff --git a/website/0.8.3/pom.xml b/website/0.8.3/pom.xml new file mode 100644 index 0000000..bde9265 --- /dev/null +++ b/website/0.8.3/pom.xml @@ -0,0 +1,51 @@ +<?xml version="1.0" encoding="UTF-8" ?> +<!-- +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. +--> +<project xmlns="http://maven.apache.org/POM/4.0.0"; xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"; xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd";> + <modelVersion>4.0.0</modelVersion> + + <parent> + <groupId>org.apache.helix</groupId> + <artifactId>website</artifactId> + <version>0.8.4-SNAPSHOT</version> + </parent> + + <artifactId>0.8.3-docs</artifactId> + <packaging>bundle</packaging> + <name>Apache Helix :: Website :: 0.8.3</name> + + <properties> + </properties> + + <dependencies> + <dependency> + <groupId>org.testng</groupId> + <artifactId>testng</artifactId> + <version>6.0.1</version> + </dependency> + </dependencies> + <build> + <pluginManagement> + <plugins> + </plugins> + </pluginManagement> + <plugins> + </plugins> + </build> +</project> http://git-wip-us.apache.org/repos/asf/helix/blob/e8125e8b/website/0.8.3/src/site/apt/privacy-policy.apt ---------------------------------------------------------------------- diff --git a/website/0.8.3/src/site/apt/privacy-policy.apt b/website/0.8.3/src/site/apt/privacy-policy.apt new file mode 100644 index 0000000..ada9363 --- /dev/null +++ b/website/0.8.3/src/site/apt/privacy-policy.apt @@ -0,0 +1,52 @@ + ---- + Privacy Policy + ----- + Olivier Lamy + ----- + 2013-02-04 + ----- + +~~ 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. + +Privacy Policy + + Information about your use of this website is collected using server access logs and a tracking cookie. The + collected information consists of the following: + + [[1]] The IP address from which you access the website; + + [[2]] The type of browser and operating system you use to access our site; + + [[3]] The date and time you access our site; + + [[4]] The pages you visit; and + + [[5]] The addresses of pages from where you followed a link to our site. + + [] + + Part of this information is gathered using a tracking cookie set by the + {{{http://www.google.com/analytics/}Google Analytics}} service and handled by Google as described in their + {{{http://www.google.com/privacy.html}privacy policy}}. See your browser documentation for instructions on how to + disable the cookie if you prefer not to share this data with Google. + + We use the gathered information to help us make our site more useful to visitors and to better understand how and + when our site is used. We do not track or collect personally identifiable information or associate gathered data + with any personally identifying information from other sources. + + By using this website, you consent to the collection of this data in the manner and for the purpose described above. http://git-wip-us.apache.org/repos/asf/helix/blob/e8125e8b/website/0.8.3/src/site/apt/releasenotes/release-0.8.3.apt ---------------------------------------------------------------------- diff --git a/website/0.8.3/src/site/apt/releasenotes/release-0.8.3.apt b/website/0.8.3/src/site/apt/releasenotes/release-0.8.3.apt new file mode 100644 index 0000000..e7b5e1c --- /dev/null +++ b/website/0.8.3/src/site/apt/releasenotes/release-0.8.3.apt @@ -0,0 +1,80 @@ + ----- + Release Notes for Apache Helix 0.8.3 + ----- + +~~ 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. + +~~ NOTE: For help with the syntax of this file, see: +~~ http://maven.apache.org/guides/mini/guide-apt-format.html + +Release Notes for Apache Helix 0.8.3 + + The Apache Helix team would like to announce the release of Apache Helix 0.8.3. + + This is the fifteenth release under the Apache umbrella, and the eleventh as a top-level project. + + Helix is a generic cluster management framework used for the automatic management of partitioned, replicated and distributed resources hosted on a cluster of nodes. + + In this release, Helix provides several performance improvements for rebalance pipeline: + +[] + +* Detailed Changes + +** New Features + + * Introduce Helix ZkClient factory. And use the factory to generate new ZkClient in the critical Helix components + + * [helix-front] Add maintenance mode support + + * [HELIX-1315] add task driver support for helix rest to add/get task framework user content + + * REST2.0: Add delete command to updateInstanceConfig + +** Bug Fixes + + * Fix a bug in stopping workflows + + * Fix mappingCalculator NPE + + * Fix a possible NPE in loadBalance in IntermediateStateCalcStage + + * Fix a race condition in updatePreviousAssignedTasksStatus + + * Fix redundant DROPPED message sent to participant + + * Fix external view does not remove old ones + +** Improvements + + * Selective update for Resource Config read + + * Async purge job for task framework + + * Improve the logic for Task Context update + + * Batch write operations of task framework context update + + * Change all Helix default created ZkClients to use ZnRecordSerializer. + + * Improve helix message timeout task +[] + +Cheers, +-- +The Apache Helix Team http://git-wip-us.apache.org/repos/asf/helix/blob/e8125e8b/website/0.8.3/src/site/markdown/Building.md ---------------------------------------------------------------------- diff --git a/website/0.8.3/src/site/markdown/Building.md b/website/0.8.3/src/site/markdown/Building.md new file mode 100644 index 0000000..27d65f9 --- /dev/null +++ b/website/0.8.3/src/site/markdown/Building.md @@ -0,0 +1,42 @@ +<!--- +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. +--> + +Build Instructions +------------------ + +### From Source + +Requirements: JDK 1.6+, Maven 2.0.8+ + +``` +git clone https://git-wip-us.apache.org/repos/asf/helix.git +cd helix +git checkout tags/helix-0.8.3 +mvn install package -DskipTests +``` + +### Maven Dependency + +``` +<dependency> + <groupId>org.apache.helix</groupId> + <artifactId>helix-core</artifactId> + <version>0.8.3</version> +</dependency> +``` http://git-wip-us.apache.org/repos/asf/helix/blob/e8125e8b/website/0.8.3/src/site/markdown/Features.md ---------------------------------------------------------------------- diff --git a/website/0.8.3/src/site/markdown/Features.md b/website/0.8.3/src/site/markdown/Features.md new file mode 100644 index 0000000..ba9d0e7 --- /dev/null +++ b/website/0.8.3/src/site/markdown/Features.md @@ -0,0 +1,313 @@ +<!--- +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> + <title>Features</title> +</head> + +Features +---------------------------- + + +### CONFIGURING IDEALSTATE + + +Read concepts page for definition of Idealstate. + +The placement of partitions in a DDS is very critical for reliability and scalability of the system. +For example, when a node fails, it is important that the partitions hosted on that node are reallocated evenly among the remaining nodes. Consistent hashing is one such algorithm that can guarantee this. +Helix by default comes with a variant of consistent hashing based of the RUSH algorithm. + +This means given a number of partitions, replicas and number of nodes Helix does the automatic assignment of partition to nodes such that + +* Each node has the same number of partitions and replicas of the same partition do not stay on the same node. +* When a node fails, the partitions will be equally distributed among the remaining nodes +* When new nodes are added, the number of partitions moved will be minimized along with satisfying the above two criteria. + + +Helix provides multiple ways to control the placement and state of a replica. + +``` + + |AUTO REBALANCE| AUTO | CUSTOM | + ----------------------------------------- + LOCATION | HELIX | APP | APP | + ----------------------------------------- + STATE | HELIX | HELIX | APP | + ----------------------------------------- +``` + +#### HELIX EXECUTION MODE + + +Idealstate is defined as the state of the DDS when all nodes are up and running and healthy. +Helix uses this as the target state of the system and computes the appropriate transitions needed in the system to bring it to a stable state. + +Helix supports 3 different execution modes which allows application to explicitly control the placement and state of the replica. + +##### AUTO_REBALANCE + +When the idealstate mode is set to AUTO_REBALANCE, Helix controls both the location of the replica along with the state. This option is useful for applications where creation of a replica is not expensive. Example + +``` +{ + "id" : "MyResource", + "simpleFields" : { + "IDEAL_STATE_MODE" : "AUTO_REBALANCE", + "NUM_PARTITIONS" : "3", + "REPLICAS" : "2", + "STATE_MODEL_DEF_REF" : "MasterSlave", + } + "listFields" : { + "MyResource_0" : [], + "MyResource_1" : [], + "MyResource_2" : [] + }, + "mapFields" : { + } +} +``` + +If there are 3 nodes in the cluster, then Helix will internally compute the ideal state as + +``` +{ + "id" : "MyResource", + "simpleFields" : { + "NUM_PARTITIONS" : "3", + "REPLICAS" : "2", + "STATE_MODEL_DEF_REF" : "MasterSlave", + }, + "mapFields" : { + "MyResource_0" : { + "N1" : "MASTER", + "N2" : "SLAVE", + }, + "MyResource_1" : { + "N2" : "MASTER", + "N3" : "SLAVE", + }, + "MyResource_2" : { + "N3" : "MASTER", + "N1" : "SLAVE", + } + } +} +``` + +Another typical example is evenly distributing a group of tasks among the currently alive processes. For example, if there are 60 tasks and 4 nodes, Helix assigns 15 tasks to each node. +When one node fails Helix redistributes its 15 tasks to the remaining 3 nodes. Similarly, if a node is added, Helix re-allocates 3 tasks from each of the 4 nodes to the 5th node. + +#### AUTO + +When the idealstate mode is set to AUTO, Helix only controls STATE of the replicas where as the location of the partition is controlled by application. Example: The below idealstate indicates thats 'MyResource_0' must be only on node1 and node2. But gives the control of assigning the STATE to Helix. + +``` +{ + "id" : "MyResource", + "simpleFields" : { + "IDEAL_STATE_MODE" : "AUTO", + "NUM_PARTITIONS" : "3", + "REPLICAS" : "2", + "STATE_MODEL_DEF_REF" : "MasterSlave", + } + "listFields" : { + "MyResource_0" : [node1, node2], + "MyResource_1" : [node2, node3], + "MyResource_2" : [node3, node1] + }, + "mapFields" : { + } +} +``` +In this mode when node1 fails, unlike in AUTO-REBALANCE mode the partition is not moved from node1 to others nodes in the cluster. Instead, Helix will decide to change the state of MyResource_0 in N2 based on the system constraints. For example, if a system constraint specified that there should be 1 Master and if the Master failed, then node2 will be made the new master. + +#### CUSTOM + +Helix offers a third mode called CUSTOM, in which application can completely control the placement and state of each replica. Applications will have to implement an interface that Helix will invoke when the cluster state changes. +Within this callback, the application can recompute the idealstate. Helix will then issue appropriate transitions such that Idealstate and Currentstate converges. + +``` +{ + "id" : "MyResource", + "simpleFields" : { + "IDEAL_STATE_MODE" : "CUSTOM", + "NUM_PARTITIONS" : "3", + "REPLICAS" : "2", + "STATE_MODEL_DEF_REF" : "MasterSlave", + }, + "mapFields" : { + "MyResource_0" : { + "N1" : "MASTER", + "N2" : "SLAVE", + }, + "MyResource_1" : { + "N2" : "MASTER", + "N3" : "SLAVE", + }, + "MyResource_2" : { + "N3" : "MASTER", + "N1" : "SLAVE", + } + } +} +``` + +For example, the current state of the system might be 'MyResource_0' -> {N1:MASTER,N2:SLAVE} and the application changes the ideal state to 'MyResource_0' -> {N1:SLAVE,N2:MASTER}. Helix will not blindly issue MASTER-->SLAVE to N1 and SLAVE-->MASTER to N2 in parallel since it might result in a transient state where both N1 and N2 are masters. +Helix will first issue MASTER-->SLAVE to N1 and after its completed it will issue SLAVE-->MASTER to N2. + + +### State Machine Configuration + +Helix comes with 3 default state models that are most commonly used. Its possible to have multiple state models in a cluster. +Every resource that is added should have a reference to the state model. + +* MASTER-SLAVE: Has 3 states OFFLINE,SLAVE,MASTER. Max masters is 1. Slaves will be based on the replication factor. Replication factor can be specified while adding the resource +* ONLINE-OFFLINE: Has 2 states OFFLINE and ONLINE. Very simple state model and most applications start off with this state model. +* LEADER-STANDBY:1 Leader and many stand bys. In general the standby's are idle. + +Apart from providing the state machine configuration, one can specify the constraints of states and transitions. + +For example one can say +Master:1. Max number of replicas in Master state at any time is 1. +OFFLINE-SLAVE:5 Max number of Offline-Slave transitions that can happen concurrently in the system + +STATE PRIORITY +Helix uses greedy approach to satisfy the state constraints. For example if the state machine configuration says it needs 1 master and 2 slaves but only 1 node is active, Helix must promote it to master. This behavior is achieved by providing the state priority list as MASTER,SLAVE. + +STATE TRANSITION PRIORITY +Helix tries to fire as many transitions as possible in parallel to reach the stable state without violating constraints. By default Helix simply sorts the transitions alphabetically and fires as many as it can without violating the constraints. +One can control this by overriding the priority order. + +### Config management + +Helix allows applications to store application specific properties. The configuration can have different scopes. + +* Cluster +* Node specific +* Resource specific +* Partition specific + +Helix also provides notifications when any configs are changed. This allows applications to support dynamic configuration changes. + +See HelixManager.getConfigAccessor for more info + +### Intra cluster messaging api + +This is an interesting feature which is quite useful in practice. Often times, nodes in DDS requires a mechanism to interact with each other. One such requirement is a process of bootstrapping a replica. + +Consider a search system use case where the index replica starts up and it does not have an index. One of the commonly used solutions is to get the index from a common location or to copy the index from another replica. +Helix provides a messaging api, that can be used to talk to other nodes in the system. The value added that Helix provides here is, message recipient can be specified in terms of resource, +partition, state and Helix ensures that the message is delivered to all of the required recipients. In this particular use case, the instance can specify the recipient criteria as all replicas of P1. +Since Helix is aware of the global state of the system, it can send the message to appropriate nodes. Once the nodes respond Helix provides the bootstrapping replica with all the responses. + +This is a very generic api and can also be used to schedule various periodic tasks in the cluster like data backups etc. +System Admins can also perform adhoc tasks like on demand backup or execute a system command(like rm -rf ;-)) across all nodes. + +``` + ClusterMessagingService messagingService = manager.getMessagingService(); + //CONSTRUCT THE MESSAGE + Message requestBackupUriRequest = new Message( + MessageType.USER_DEFINE_MSG, UUID.randomUUID().toString()); + requestBackupUriRequest + .setMsgSubType(BootstrapProcess.REQUEST_BOOTSTRAP_URL); + requestBackupUriRequest.setMsgState(MessageState.NEW); + //SET THE RECIPIENT CRITERIA, All nodes that satisfy the criteria will receive the message + Criteria recipientCriteria = new Criteria(); + recipientCriteria.setInstanceName("%"); + recipientCriteria.setRecipientInstanceType(InstanceType.PARTICIPANT); + recipientCriteria.setResource("MyDB"); + recipientCriteria.setPartition(""); + //Should be processed only the process that is active at the time of sending the message. + //This means if the recipient is restarted after message is sent, it will not be processed. + recipientCriteria.setSessionSpecific(true); + // wait for 30 seconds + int timeout = 30000; + //The handler that will be invoked when any recipient responds to the message. + BootstrapReplyHandler responseHandler = new BootstrapReplyHandler(); + //This will return only after all recipients respond or after timeout. + int sentMessageCount = messagingService.sendAndWait(recipientCriteria, + requestBackupUriRequest, responseHandler, timeout); +``` + +See HelixManager.getMessagingService for more info. + + +### Application specific property storage + +There are several usecases where applications needs support for distributed data structures. Helix uses Zookeeper to store the application data and hence provides notifications when the data changes. +One value add Helix provides is the ability to specify cache the data and also write through cache. This is more efficient than reading from ZK every time. + +See HelixManager.getHelixPropertyStore + +### Throttling + +Since all state changes in the system are triggered through transitions, Helix can control the number of transitions that can happen in parallel. Some of the transitions may be light weight but some might involve moving data around which is quite expensive. +Helix allows applications to set threshold on transitions. The threshold can be set at the multiple scopes. + +* MessageType e.g STATE_TRANSITION +* TransitionType e.g SLAVE-MASTER +* Resource e.g database +* Node i.e per node max transitions in parallel. + +See HelixManager.getHelixAdmin.addMessageConstraint() + +### Health monitoring and alerting + +This in currently in development mode, not yet productionized. + +Helix provides ability for each node in the system to report health metrics on a periodic basis. +Helix supports multiple ways to aggregate these metrics like simple SUM, AVG, EXPONENTIAL DECAY, WINDOW. Helix will only persist the aggregated value. +Applications can define threshold on the aggregate values according to the SLA's and when the SLA is violated Helix will fire an alert. +Currently Helix only fires an alert but eventually we plan to use this metrics to either mark the node dead or load balance the partitions. +This feature will be valuable in for distributed systems that support multi-tenancy and have huge variation in work load patterns. Another place this can be used is to detect skewed partitions and rebalance the cluster. + +This feature is not yet stable and do not recommend to be used in production. + + +### Controller deployment modes + +Read Architecture wiki for more details on the Role of a controller. In simple words, it basically controls the participants in the cluster by issuing transitions. + +Helix provides multiple options to deploy the controller. + +#### STANDALONE + +Controller can be started as a separate process to manage a cluster. This is the recommended approach. How ever since one controller can be a single point of failure, multiple controller processes are required for reliability. +Even if multiple controllers are running only one will be actively managing the cluster at any time and is decided by a leader election process. If the leader fails, another leader will resume managing the cluster. + +Even though we recommend this method of deployment, it has the drawback of having to manage an additional service for each cluster. See Controller As a Service option. + +#### EMBEDDED + +If setting up a separate controller process is not viable, then it is possible to embed the controller as a library in each of the participant. + +#### CONTROLLER AS A SERVICE + +One of the cool feature we added in helix was use a set of controllers to manage a large number of clusters. +For example if you have X clusters to be managed, instead of deploying X*3(3 controllers for fault tolerance) controllers for each cluster, one can deploy only 3 controllers. Each controller can manage X/3 clusters. +If any controller fails the remaining two will manage X/2 clusters. At LinkedIn, we always deploy controllers in this mode. + + + + + + + + http://git-wip-us.apache.org/repos/asf/helix/blob/e8125e8b/website/0.8.3/src/site/markdown/Metrics.md ---------------------------------------------------------------------- diff --git a/website/0.8.3/src/site/markdown/Metrics.md b/website/0.8.3/src/site/markdown/Metrics.md new file mode 100644 index 0000000..3a67b69 --- /dev/null +++ b/website/0.8.3/src/site/markdown/Metrics.md @@ -0,0 +1,217 @@ +<!--- +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. +--> + +Helix Monitoring Metrics +------------------ + +Helix monitoring metrics are exposed as the MBeans attributes. +The MBeans are registered based on instance role. + +The easiest way to see the available metrics is using jconsole and point it at a running Helix instance. +This will allow browsing all metrics with JMX. + +Note that if not mentioned in the attribute name, all attributes are gauge by default. + +### Metrics on Both Controller and Participant + +#### MBean ZkClientMonitor +ObjectName: "HelixZkClient:type=[client-type],key=[specified-client-key],PATH=[zk-client-listening-path]" + +|Attributes|Description| +|----------|-----------| +|ReadCounter|Zk Read counter. Which could be used to identify unusually high/low ZK traffic| +|WriteCounter|Same as above| +|ReadBytesCounter|Same as above| +|WriteBytesCounter|Same as above| +|StateChangeEventCounter|Zk connection state change counter. Which could be used to identify ZkClient unstable connection| +|DataChangeEventCounter|Zk node data change counter. which could be used to identify unusual high/low ZK events occurrence or slow event processing| +|PendingCallbackGauge|Number of the pending Zk callbacks.| +|TotalCallbackCounter|Number of total received Zk callbacks.| +|TotalCallbackHandledCounter|Number of total handled Zk callbacks.| +|ReadTotalLatencyCounter|Total read latency in ms.| +|WriteTotalLatencyCounter|Total write latency in ms.| +|WriteFailureCounter|Total write failures.| +|ReadFailureCounter|Total read failures.| +|ReadLatencyGauge|Histogram (with all statistic data) of read latency.| +|WriteLatencyGauge|Histogram (with all statistic data) of write latency.| +|ReadBytesGauge|Histogram (with all statistic data) of read bytes of single Zk access.| +|WriteBytesGauge|Histogram (with all statistic data) of write bytes of single Zk access.| + +#### MBean HelixCallbackMonitor +ObjectName: "HelixCallback:Type=[callback-type],Key=[cluster-name].[instance-name],Change=[callback-change-type]" + +|Attributes|Description| +|----------|-----------| +|Counter|Zk Callback counter for each Helix callback type.| +|UnbatchedCounter|Unbatched Zk Callback counter for each helix callback type.| +|LatencyCounter|Callback handler latency counter in ms.| +|LatencyGauge|Histogram (with all statistic data) of Callback handler latency.| + +#### MBean MessageQueueMonitor +ObjectName: "ClusterStatus:cluster=[cluster-name],messageQueue=[instance-name]" + +|Attributes|Description| +|----------|-----------| +|MessageQueueBacklog|Get the message queue size| + +### Metrics on Controller only + +#### MBean ClusterStatusMonitor +ObjectName: "ClusterStatus:cluster=[cluster-name]" + +|Attributes|Description| +|----------|-----------| +|DisabledInstancesGauge|Current number of disabled instances| +|DisabledPartitionsGauge|Current number of disabled partitions number| +|DownInstanceGauge|Current down instances number| +|InstanceMessageQueueBacklog|The sum of all message queue sizes for instances in this cluster| +|InstancesGauge|Current live instances number| +|MaxMessageQueueSizeGauge|The maximum message queue size across all instances including controller| +|RebalanceFailureGauge|None 0 if previous rebalance failed unexpectedly. The Gauge will be set every time rebalance is done.| +|RebalanceFailureCounter|The number of failures during rebalance pipeline.| +|Enabled|1 if cluster is enabled, otherwise 0| +|Maintenance|1 if cluster is in maintenance mode, otherwise 0| +|Paused|1 if cluster is paused, otherwise 0| + +#### MBean ClusterEventMonitor +ObjectName: "ClusterStatus:cluster=[cluster-name],eventName=ClusterEvent,phaseName=[event-handling-phase]" + +|Attributes|Description| +|----------|-----------| +|TotalDurationCounter|Total event process duration for each stage.| +|MaxSingleDurationGauge|Max event process duration for each stage within the recent hour.| +|EventCounter|The count of processed event in each stage.| +|DurationGauge|Histogram (with all statistic data) of event process duration for each stage.| + +#### MBean InstanceMonitor +ObjectName: "ClusterStatus:cluster=[cluster-name],instanceName=[instance-name]" + +|Attributes|Description| +|----------|-----------| +|Online|This instance is Online (1) or Offline (0)| +|Enabled|This instance is Enabled (1) or Disabled (0)| +|TotalMessageReceived|Number of messages sent to this instance by controller| +|DisabledPartitions|Get the total disabled partitions number for this instance| + +#### MBean ResourceMonitor +ObjectName: "ClusterStatus:cluster=[cluster-name],resourceName=[resource-name]" + +|Attributes|Description| +|----------|-----------| +|PartitionGauge|Get number of partitions of the resource in best possible ideal state for this resource| +|ErrorPartitionGauge|Get the number of current partitions in ERORR state for this resource| +|DifferenceWithIdealStateGauge|Get the number of how many replicas' current state are different from ideal state for this resource| +|MissingTopStatePartitionGauge|Get the number of partitions do not have top state for this resource| +|ExternalViewPartitionGauge|Get number of partitions in ExternalView for this resource| +|TotalMessageReceived|Get number of messages sent to this resource by controller| +|LoadRebalanceThrottledPartitionGauge|Get number of partitions that need load rebalance but were throttled.| +|RecoveryRebalanceThrottledPartitionGauge|Get number of partitions that need recovery rebalance but were throttled.| +|PendingLoadRebalancePartitionGauge|Get number of partitions that have pending load rebalance requests.| +|PendingRecoveryRebalancePartitionGauge|Get number of partitions that have pending recovery rebalance requests.| +|MissingReplicaPartitionGauge|Get number of partitions that have replica number smaller than expected.| +|MissingMinActiveReplicaPartitionGauge|Get number of partitions that have replica number smaller than the minimum requirement.| +|MaxSinglePartitionTopStateHandoffDurationGauge|Get the max duration recorded when the top state is missing in any single partition.| +|FailedTopStateHandoffCounter| Get the number of total top state transition failure.| +|SucceededTopStateHandoffCounter|Get the number of total top state transition done successfully.| +|SuccessfulTopStateHandoffDurationCounter|Get the total duration of all top state transitions.| +|PartitionTopStateHandoffDurationGauge|Histogram (with all statistic data) of top state transition duration.| + +#### MBean PerInstanceResourceMonitor +ObjectName: "ClusterStatus:cluster=[cluster-name],instanceName=[instance-name],resourceName=[resource-name]" + +|Attributes|Description| +|----------|-----------| +|PartitionGauge|Get number of partitions of the resource in best possible ideal state for this resource on specific instance| + +#### MBean JobMonitor +ObjectName: "ClusterStatus:cluster=[cluster-name],jobType=[job-type]" + +|Attributes|Description| +|----------|-----------| +|SuccessfulJobCount|Get number of the succeeded jobs| +|FailedJobCount|Get number of failed jobs| +|AbortedJobCount|Get number of the aborted jobs| +|ExistingJobGauge|Get number of existing jobs registered| +|QueuedJobGauge|Get numbers of queued jobs, which are not running jobs| +|RunningJobGauge|Get numbers of running jobs| +|MaximumJobLatencyGauge|Get maximum latency of jobs running time. It will be cleared every hour| +|JobLatencyCount|Get total job latency counter.| + +#### MBean WorkflowMonitor +ObjectName: "ClusterStatus:cluster=[cluster-name],workflowType=[workflow-type]" + +|Attributes|Description| +|----------|-----------| +|SuccessfulWorkflowCount|Get number of succeeded workflows| +|FailedWorkflowCount|Get number of failed workflows| +|FailedWorkflowGauge|Get number of current failed workflows| +|ExistingWorkflowGauge|Get number of current existing workflows| +|QueuedWorkflowGauge|Get number of queued but not started workflows| +|RunningWorkflowGauge|Get number of running workflows| +|WorkflowLatencyCount|Get workflow latency count| +|MaximumWorkflowLatencyGauge|Get maximum workflow latency gauge. It will be reset in 1 hour.| + +### Metrics on Participant only + +#### MBean StateTransitionStatMonitor +ObjectName: "CLMParticipantReport:Cluster=[cluster-name],Resource=[resource-name],Transition=[transaction-id]" + +|Attributes|Description| +|----------|-----------| +|TotalStateTransitionGauge|Get the number of total state transitions| +|TotalFailedTransitionGauge|Get the number of total failed state transitions| +|TotalSuccessTransitionGauge|Get the number of total succeeded state transitions| +|MeanTransitionLatency|Get the average state transition latency (from message read to finish)| +|MaxTransitionLatency|Get the maximum state transition latency| +|MinTransitionLatency|Get the minimum state transition latency| +|PercentileTransitionLatency|Get the percentile of state transitions latency| +|MeanTransitionExecuteLatency|Get the average execution latency of state transition (from task started to finish)| +|MaxTransitionExecuteLatency|Get the maximum execution latency of state transition| +|MinTransitionExecuteLatency|Get the minimum execution latency of state transition| +|PercentileTransitionExecuteLatency|Get the percentile of execution latency of state transitions| + +#### MBean ThreadPoolExecutorMonitor +ObjectName: "HelixThreadPoolExecutor:Type=[threadpool-type]" (threadpool-type in Message.MessageType, BatchMessageExecutor, Task) + +|Attributes|Description| +|----------|-----------| +|ThreadPoolCoreSizeGauge|Thread pool size is as configured. Aggregate total thread pool size for the whole cluster.| +|ThreadPoolMaxSizeGauge|Same as above| +|NumOfActiveThreadsGauge|Number of running threads.| +|QueueSizeGauge|Queue size. Could be used to identify if too many HelixTask blocked in participant.| + +#### MBean MessageLatencyMonitor +ObjectName: "CLMParticipantReport:ParticipantName=[instance-name],MonitorType=MessageLatencyMonitor" + +|Attributes|Description| +|----------|-----------| +|TotalMessageCount|Total message count| +|TotalMessageLatency|Total message latency in ms| +|MessagelatencyGauge|Histogram (with all statistic data) of message processing latency.| + +#### MBean ParticipantMessageMonitor +ObjectName: "CLMParticipantReport:ParticipantName=[instance-name]" + +|Attributes|Description| +|----------|-----------| +|ReceivedMessages|Number of received messages| +|DiscardedMessages|Number of discarded messages| +|CompletedMessages|Number of completed messages| +|FailedMessages|Number of failed messages| +|PendingMessages|Number of pending messages to be processed| http://git-wip-us.apache.org/repos/asf/helix/blob/e8125e8b/website/0.8.3/src/site/markdown/Quickstart.md ---------------------------------------------------------------------- diff --git a/website/0.8.3/src/site/markdown/Quickstart.md b/website/0.8.3/src/site/markdown/Quickstart.md new file mode 100644 index 0000000..8af84e8 --- /dev/null +++ b/website/0.8.3/src/site/markdown/Quickstart.md @@ -0,0 +1,663 @@ +<!--- +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> + <title>Quickstart</title> +</head> + +Quickstart +--------- + +Get Helix +--------- + +First, let\'s get Helix. Either build it, or download it. + +### Build + +``` +git clone https://git-wip-us.apache.org/repos/asf/helix.git +cd helix +git checkout tags/helix-0.8.3 +mvn install package -DskipTests +cd helix-core/target/helix-core-pkg/bin # This folder contains all the scripts used in following sections +chmod +x * +``` + +### Download + +Download the 0.8.3 release package [here](./download.html) + +Overview +-------- + +In this Quickstart, we\'ll set up a master-slave replicated, partitioned system. Then we\'ll demonstrate how to add a node, rebalance the partitions, and show how Helix manages failover. + + +Let\'s Do It +------------ + +Helix provides command line interfaces to set up the cluster and view the cluster state. The best way to understand how Helix views a cluster is to build a cluster. + +### Get to the Tools Directory + +If you built the code: + +``` +cd helix/helix/helix-core/target/helix-core-pkg/bin +``` + +If you downloaded the release package, extract it. + + +Short Version +------------- +You can observe the components working together in this demo, which does the following: + +* Create a cluster +* Add 2 nodes (participants) to the cluster +* Set up a resource with 6 partitions and 2 replicas: 1 Master, and 1 Slave per partition +* Show the cluster state after Helix balances the partitions +* Add a third node +* Show the cluster state. Note that the third node has taken mastership of 2 partitions. +* Kill the third node (Helix takes care of failover) +* Show the cluster state. Note that the two surviving nodes take over mastership of the partitions from the failed node + +### Run the Demo + +``` +cd helix/helix/helix-core/target/helix-core-pkg/bin +./quickstart.sh +``` + +#### The Initial Setup + +2 nodes are set up and the partitions are rebalanced. + +The cluster state is as follows: + +``` +CLUSTER STATE: After starting 2 nodes + localhost_12000 localhost_12001 +MyResource_0 M S +MyResource_1 S M +MyResource_2 M S +MyResource_3 M S +MyResource_4 S M +MyResource_5 S M +``` + +Note there is one master and one slave per partition. + +#### Add a Node + +A third node is added and the cluster is rebalanced. + +The cluster state changes to: + +``` +CLUSTER STATE: After adding a third node + localhost_12000 localhost_12001 localhost_12002 +MyResource_0 S M S +MyResource_1 S S M +MyResource_2 M S S +MyResource_3 S S M +MyResource_4 M S S +MyResource_5 S M S +``` + +Note there is one master and _two_ slaves per partition. This is expected because there are three nodes. + +#### Kill a Node + +Finally, a node is killed to simulate a failure + +Helix makes sure each partition has a master. The cluster state changes to: + +``` +CLUSTER STATE: After the 3rd node stops/crashes + localhost_12000 localhost_12001 localhost_12002 +MyResource_0 S M - +MyResource_1 S M - +MyResource_2 M S - +MyResource_3 M S - +MyResource_4 M S - +MyResource_5 S M - +``` + + +Long Version +------------ +Now you can run the same steps by hand. In this detailed version, we\'ll do the following: + +* Define a cluster +* Add two nodes to the cluster +* Add a 6-partition resource with 1 master and 2 slave replicas per partition +* Verify that the cluster is healthy and inspect the Helix view +* Expand the cluster: add a few nodes and rebalance the partitions +* Failover: stop a node and verify the mastership transfer + +### Install and Start ZooKeeper + +Zookeeper can be started in standalone mode or replicated mode. + +More information is available at + +* http://zookeeper.apache.org/doc/r3.3.3/zookeeperStarted.html +* http://zookeeper.apache.org/doc/trunk/zookeeperAdmin.html#sc_zkMulitServerSetup + +In this example, let\'s start zookeeper in local mode. + +#### Start ZooKeeper Locally on Port 2199 + +``` +./start-standalone-zookeeper.sh 2199 & +``` + +### Define the Cluster + +The helix-admin tool is used for cluster administration tasks. In the Quickstart, we\'ll use the command line interface. Helix supports a REST interface as well. + +zookeeper_address is of the format host:port e.g localhost:2199 for standalone or host1:port,host2:port for multi-node. + +Next, we\'ll set up a cluster MYCLUSTER cluster with these attributes: + +* 3 instances running on localhost at ports 12913,12914,12915 +* One database named myDB with 6 partitions +* Each partition will have 3 replicas with 1 master, 2 slaves +* ZooKeeper running locally at localhost:2199 + +#### Create the Cluster MYCLUSTER + +``` +# ./helix-admin.sh --zkSvr <zk_address> --addCluster <clustername> +./helix-admin.sh --zkSvr localhost:2199 --addCluster MYCLUSTER +``` + +### Add Nodes to the Cluster + +In this case we\'ll add three nodes: localhost:12913, localhost:12914, localhost:12915 + +``` +# helix-admin.sh --zkSvr <zk_address> --addNode <clustername> <host:port> +./helix-admin.sh --zkSvr localhost:2199 --addNode MYCLUSTER localhost:12913 +./helix-admin.sh --zkSvr localhost:2199 --addNode MYCLUSTER localhost:12914 +./helix-admin.sh --zkSvr localhost:2199 --addNode MYCLUSTER localhost:12915 +``` + +### Define the Resource and Partitioning + +In this example, the resource is a database, partitioned 6 ways. Note that in a production system, it\'s common to over-partition for better load balancing. Helix has been used in production to manage hundreds of databases each with 10s or 100s of partitions running on 10s of physical nodes. + +#### Create a Database with 6 Partitions using the MasterSlave State Model + +Helix ensures there will be exactly one master for each partition. + +``` +# helix-admin.sh --zkSvr <zk_address> --addResource <clustername> <resourceName> <numPartitions> <StateModelName> +./helix-admin.sh --zkSvr localhost:2199 --addResource MYCLUSTER myDB 6 MasterSlave +``` + +#### Let Helix Assign Partitions to Nodes + +This command will distribute the partitions amongst all the nodes in the cluster. In this example, each partition has 3 replicas. + +``` +# helix-admin.sh --zkSvr <zk_address> --rebalance <clustername> <resourceName> <replication factor> +./helix-admin.sh --zkSvr localhost:2199 --rebalance MYCLUSTER myDB 3 +``` + +Now the cluster is defined in ZooKeeper. The nodes (localhost:12913, localhost:12914, localhost:12915) and resource (myDB, with 6 partitions using the MasterSlave model) are all properly configured. And the _IdealState_ has been calculated, assuming a replication factor of 3. + +### Start the Helix Controller + +Now that the cluster is defined in ZooKeeper, the Helix controller can manage the cluster. + +``` +# Start the cluster manager, which will manage MYCLUSTER +./run-helix-controller.sh --zkSvr localhost:2199 --cluster MYCLUSTER 2>&1 > /tmp/controller.log & +``` + +### Start up the Cluster to be Managed + +We\'ve started up ZooKeeper, defined the cluster, the resources, the partitioning, and started up the Helix controller. Next, we\'ll start up the nodes of the system to be managed. Each node is a Participant, which is an instance of the system component to be managed. Helix assigns work to Participants, keeps track of their roles and health, and takes action when a node fails. + +``` +# start up each instance. These are mock implementations that are actively managed by Helix +./start-helix-participant.sh --zkSvr localhost:2199 --cluster MYCLUSTER --host localhost --port 12913 --stateModelType MasterSlave 2>&1 > /tmp/participant_12913.log +./start-helix-participant.sh --zkSvr localhost:2199 --cluster MYCLUSTER --host localhost --port 12914 --stateModelType MasterSlave 2>&1 > /tmp/participant_12914.log +./start-helix-participant.sh --zkSvr localhost:2199 --cluster MYCLUSTER --host localhost --port 12915 --stateModelType MasterSlave 2>&1 > /tmp/participant_12915.log +``` + +### Inspect the Cluster + +Now, let\'s see the Helix view of our cluster. We\'ll work our way down as follows: + +``` +Clusters -> MYCLUSTER -> instances -> instance detail + -> resources -> resource detail + -> partitions +``` + +A single Helix controller can manage multiple clusters, though so far, we\'ve only defined one cluster. Let\'s see: + +``` +# List existing clusters +./helix-admin.sh --zkSvr localhost:2199 --listClusters + +Existing clusters: +MYCLUSTER +``` + +Now, let\'s see the Helix view of MYCLUSTER: + +``` +# helix-admin.sh --zkSvr <zk_address> --listClusterInfo <clusterName> +./helix-admin.sh --zkSvr localhost:2199 --listClusterInfo MYCLUSTER + +Existing resources in cluster MYCLUSTER: +myDB +Instances in cluster MYCLUSTER: +localhost_12915 +localhost_12914 +localhost_12913 +``` + +Let\'s look at the details of an instance: + +``` +# ./helix-admin.sh --zkSvr <zk_address> --listInstanceInfo <clusterName> <InstanceName> +./helix-admin.sh --zkSvr localhost:2199 --listInstanceInfo MYCLUSTER localhost_12913 + +InstanceConfig: { + "id" : "localhost_12913", + "mapFields" : { + }, + "listFields" : { + }, + "simpleFields" : { + "HELIX_ENABLED" : "true", + "HELIX_HOST" : "localhost", + "HELIX_PORT" : "12913" + } +} +``` + + +#### Query Information about a Resource + +``` +# helix-admin.sh --zkSvr <zk_address> --listResourceInfo <clusterName> <resourceName> +./helix-admin.sh --zkSvr localhost:2199 --listResourceInfo MYCLUSTER myDB + +IdealState for myDB: +{ + "id" : "myDB", + "mapFields" : { + "myDB_0" : { + "localhost_12913" : "SLAVE", + "localhost_12914" : "MASTER", + "localhost_12915" : "SLAVE" + }, + "myDB_1" : { + "localhost_12913" : "SLAVE", + "localhost_12914" : "SLAVE", + "localhost_12915" : "MASTER" + }, + "myDB_2" : { + "localhost_12913" : "MASTER", + "localhost_12914" : "SLAVE", + "localhost_12915" : "SLAVE" + }, + "myDB_3" : { + "localhost_12913" : "SLAVE", + "localhost_12914" : "SLAVE", + "localhost_12915" : "MASTER" + }, + "myDB_4" : { + "localhost_12913" : "MASTER", + "localhost_12914" : "SLAVE", + "localhost_12915" : "SLAVE" + }, + "myDB_5" : { + "localhost_12913" : "SLAVE", + "localhost_12914" : "MASTER", + "localhost_12915" : "SLAVE" + } + }, + "listFields" : { + "myDB_0" : [ "localhost_12914", "localhost_12913", "localhost_12915" ], + "myDB_1" : [ "localhost_12915", "localhost_12913", "localhost_12914" ], + "myDB_2" : [ "localhost_12913", "localhost_12915", "localhost_12914" ], + "myDB_3" : [ "localhost_12915", "localhost_12913", "localhost_12914" ], + "myDB_4" : [ "localhost_12913", "localhost_12914", "localhost_12915" ], + "myDB_5" : [ "localhost_12914", "localhost_12915", "localhost_12913" ] + }, + "simpleFields" : { + "IDEAL_STATE_MODE" : "AUTO", + "REBALANCE_MODE" : "SEMI_AUTO", + "NUM_PARTITIONS" : "6", + "REPLICAS" : "3", + "STATE_MODEL_DEF_REF" : "MasterSlave", + "STATE_MODEL_FACTORY_NAME" : "DEFAULT" + } +} + +ExternalView for myDB: +{ + "id" : "myDB", + "mapFields" : { + "myDB_0" : { + "localhost_12913" : "SLAVE", + "localhost_12914" : "MASTER", + "localhost_12915" : "SLAVE" + }, + "myDB_1" : { + "localhost_12913" : "SLAVE", + "localhost_12914" : "SLAVE", + "localhost_12915" : "MASTER" + }, + "myDB_2" : { + "localhost_12913" : "MASTER", + "localhost_12914" : "SLAVE", + "localhost_12915" : "SLAVE" + }, + "myDB_3" : { + "localhost_12913" : "SLAVE", + "localhost_12914" : "SLAVE", + "localhost_12915" : "MASTER" + }, + "myDB_4" : { + "localhost_12913" : "MASTER", + "localhost_12914" : "SLAVE", + "localhost_12915" : "SLAVE" + }, + "myDB_5" : { + "localhost_12913" : "SLAVE", + "localhost_12914" : "MASTER", + "localhost_12915" : "SLAVE" + } + }, + "listFields" : { + }, + "simpleFields" : { + "BUCKET_SIZE" : "0" + } +} +``` + +Now, let\'s look at one of the partitions: + +``` +# helix-admin.sh --zkSvr <zk_address> --listResourceInfo <clusterName> <partition> +./helix-admin.sh --zkSvr localhost:2199 --listResourceInfo mycluster myDB_0 +``` + +### Expand the Cluster + +Next, we\'ll show how Helix does the work that you\'d otherwise have to build into your system. When you add capacity to your cluster, you want the work to be evenly distributed. In this example, we started with 3 nodes, with 6 partitions. The partitions were evenly balanced, 2 masters and 4 slaves per node. Let\'s add 3 more nodes: localhost:12916, localhost:12917, localhost:12918 + +``` +./helix-admin.sh --zkSvr localhost:2199 --addNode MYCLUSTER localhost:12916 +./helix-admin.sh --zkSvr localhost:2199 --addNode MYCLUSTER localhost:12917 +./helix-admin.sh --zkSvr localhost:2199 --addNode MYCLUSTER localhost:12918 +``` + +And start up these instances: + +``` +# start up each instance. These are mock implementations that are actively managed by Helix +./start-helix-participant.sh --zkSvr localhost:2199 --cluster MYCLUSTER --host localhost --port 12916 --stateModelType MasterSlave 2>&1 > /tmp/participant_12916.log +./start-helix-participant.sh --zkSvr localhost:2199 --cluster MYCLUSTER --host localhost --port 12917 --stateModelType MasterSlave 2>&1 > /tmp/participant_12917.log +./start-helix-participant.sh --zkSvr localhost:2199 --cluster MYCLUSTER --host localhost --port 12918 --stateModelType MasterSlave 2>&1 > /tmp/participant_12918.log +``` + + +And now, let Helix do the work for you. To shift the work, simply rebalance. After the rebalance, each node will have one master and two slaves. + +``` +./helix-admin.sh --zkSvr localhost:2199 --rebalance MYCLUSTER myDB 3 +``` + +### View the Cluster + +OK, let\'s see how it looks: + + +``` +./helix-admin.sh --zkSvr localhost:2199 --listResourceInfo MYCLUSTER myDB + +IdealState for myDB: +{ + "id" : "myDB", + "mapFields" : { + "myDB_0" : { + "localhost_12913" : "SLAVE", + "localhost_12914" : "SLAVE", + "localhost_12917" : "MASTER" + }, + "myDB_1" : { + "localhost_12916" : "SLAVE", + "localhost_12917" : "SLAVE", + "localhost_12918" : "MASTER" + }, + "myDB_2" : { + "localhost_12913" : "MASTER", + "localhost_12917" : "SLAVE", + "localhost_12918" : "SLAVE" + }, + "myDB_3" : { + "localhost_12915" : "MASTER", + "localhost_12917" : "SLAVE", + "localhost_12918" : "SLAVE" + }, + "myDB_4" : { + "localhost_12916" : "MASTER", + "localhost_12917" : "SLAVE", + "localhost_12918" : "SLAVE" + }, + "myDB_5" : { + "localhost_12913" : "SLAVE", + "localhost_12914" : "MASTER", + "localhost_12915" : "SLAVE" + } + }, + "listFields" : { + "myDB_0" : [ "localhost_12917", "localhost_12913", "localhost_12914" ], + "myDB_1" : [ "localhost_12918", "localhost_12917", "localhost_12916" ], + "myDB_2" : [ "localhost_12913", "localhost_12917", "localhost_12918" ], + "myDB_3" : [ "localhost_12915", "localhost_12917", "localhost_12918" ], + "myDB_4" : [ "localhost_12916", "localhost_12917", "localhost_12918" ], + "myDB_5" : [ "localhost_12914", "localhost_12915", "localhost_12913" ] + }, + "simpleFields" : { + "IDEAL_STATE_MODE" : "AUTO", + "REBALANCE_MODE" : "SEMI_AUTO", + "NUM_PARTITIONS" : "6", + "REPLICAS" : "3", + "STATE_MODEL_DEF_REF" : "MasterSlave", + "STATE_MODEL_FACTORY_NAME" : "DEFAULT" + } +} + +ExternalView for myDB: +{ + "id" : "myDB", + "mapFields" : { + "myDB_0" : { + "localhost_12913" : "SLAVE", + "localhost_12914" : "SLAVE", + "localhost_12917" : "MASTER" + }, + "myDB_1" : { + "localhost_12916" : "SLAVE", + "localhost_12917" : "SLAVE", + "localhost_12918" : "MASTER" + }, + "myDB_2" : { + "localhost_12913" : "MASTER", + "localhost_12917" : "SLAVE", + "localhost_12918" : "SLAVE" + }, + "myDB_3" : { + "localhost_12915" : "MASTER", + "localhost_12917" : "SLAVE", + "localhost_12918" : "SLAVE" + }, + "myDB_4" : { + "localhost_12916" : "MASTER", + "localhost_12917" : "SLAVE", + "localhost_12918" : "SLAVE" + }, + "myDB_5" : { + "localhost_12913" : "SLAVE", + "localhost_12914" : "MASTER", + "localhost_12915" : "SLAVE" + } + }, + "listFields" : { + }, + "simpleFields" : { + "BUCKET_SIZE" : "0" + } +} +``` + +Mission accomplished. The partitions are nicely balanced. + +### How about Failover? + +Building a fault tolerant system isn\'t trivial, but with Helix, it\'s easy. Helix detects a failed instance, and triggers mastership transfer automatically. + +First, let's fail an instance. In this example, we\'ll kill localhost:12918 to simulate a failure. + +We lost localhost:12918, so myDB_1 lost its MASTER. Helix can fix that, it will transfer mastership to a healthy node that is currently a SLAVE, say localhost:12197. Helix balances the load as best as it can, given there are 6 partitions on 5 nodes. Let\'s see: + + +``` +./helix-admin.sh --zkSvr localhost:2199 --listResourceInfo MYCLUSTER myDB + +IdealState for myDB: +{ + "id" : "myDB", + "mapFields" : { + "myDB_0" : { + "localhost_12913" : "SLAVE", + "localhost_12914" : "SLAVE", + "localhost_12917" : "MASTER" + }, + "myDB_1" : { + "localhost_12916" : "SLAVE", + "localhost_12917" : "SLAVE", + "localhost_12918" : "MASTER" + }, + "myDB_2" : { + "localhost_12913" : "MASTER", + "localhost_12917" : "SLAVE", + "localhost_12918" : "SLAVE" + }, + "myDB_3" : { + "localhost_12915" : "MASTER", + "localhost_12917" : "SLAVE", + "localhost_12918" : "SLAVE" + }, + "myDB_4" : { + "localhost_12916" : "MASTER", + "localhost_12917" : "SLAVE", + "localhost_12918" : "SLAVE" + }, + "myDB_5" : { + "localhost_12913" : "SLAVE", + "localhost_12914" : "MASTER", + "localhost_12915" : "SLAVE" + } + }, + "listFields" : { + "myDB_0" : [ "localhost_12917", "localhost_12913", "localhost_12914" ], + "myDB_1" : [ "localhost_12918", "localhost_12917", "localhost_12916" ], + "myDB_2" : [ "localhost_12913", "localhost_12918", "localhost_12917" ], + "myDB_3" : [ "localhost_12915", "localhost_12918", "localhost_12917" ], + "myDB_4" : [ "localhost_12916", "localhost_12917", "localhost_12918" ], + "myDB_5" : [ "localhost_12914", "localhost_12915", "localhost_12913" ] + }, + "simpleFields" : { + "IDEAL_STATE_MODE" : "AUTO", + "REBALANCE_MODE" : "SEMI_AUTO", + "NUM_PARTITIONS" : "6", + "REPLICAS" : "3", + "STATE_MODEL_DEF_REF" : "MasterSlave", + "STATE_MODEL_FACTORY_NAME" : "DEFAULT" + } +} + +ExternalView for myDB: +{ + "id" : "myDB", + "mapFields" : { + "myDB_0" : { + "localhost_12913" : "SLAVE", + "localhost_12914" : "SLAVE", + "localhost_12917" : "MASTER" + }, + "myDB_1" : { + "localhost_12916" : "SLAVE", + "localhost_12917" : "MASTER" + }, + "myDB_2" : { + "localhost_12913" : "MASTER", + "localhost_12917" : "SLAVE" + }, + "myDB_3" : { + "localhost_12915" : "MASTER", + "localhost_12917" : "SLAVE" + }, + "myDB_4" : { + "localhost_12916" : "MASTER", + "localhost_12917" : "SLAVE" + }, + "myDB_5" : { + "localhost_12913" : "SLAVE", + "localhost_12914" : "MASTER", + "localhost_12915" : "SLAVE" + } + }, + "listFields" : { + }, + "simpleFields" : { + "BUCKET_SIZE" : "0" + } +} +``` + +As we\'ve seen in this Quickstart, Helix takes care of partitioning, load balancing, elasticity, failure detection and recovery. + +### ZooInspector + +You can view all of the underlying data by going direct to zookeeper. Use ZooInspector that comes with zookeeper to browse the data. This is a java applet (make sure you have X windows) + +To start zooinspector run the following command from <zk_install_directory>/contrib/ZooInspector + +``` +java -cp zookeeper-3.3.3-ZooInspector.jar:lib/jtoaster-1.0.4.jar:../../lib/log4j-1.2.15.jar:../../zookeeper-3.3.3.jar org.apache.zookeeper.inspector.ZooInspector +``` + +### Next + +Now that you understand the idea of Helix, read the [tutorial](./Tutorial.html) to learn how to choose the right state model and constraints for your system, and how to implement it. In many cases, the built-in features meet your requirements. And best of all, Helix is a customizable framework, so you can plug in your own behavior, while retaining the automation provided by Helix. + http://git-wip-us.apache.org/repos/asf/helix/blob/e8125e8b/website/0.8.3/src/site/markdown/Tutorial.md ---------------------------------------------------------------------- diff --git a/website/0.8.3/src/site/markdown/Tutorial.md b/website/0.8.3/src/site/markdown/Tutorial.md new file mode 100644 index 0000000..d487d99 --- /dev/null +++ b/website/0.8.3/src/site/markdown/Tutorial.md @@ -0,0 +1,207 @@ +<!--- +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> + <title>Tutorial</title> +</head> + +# Helix Tutorial + +In this tutorial, we will cover the roles of a Helix-managed cluster, and show the code you need to write to integrate with it. In many cases, there is a simple default behavior that is often appropriate, but you can also customize the behavior. + +Convention: we first cover the _basic_ approach, which is the easiest to implement. Then, we'll describe _advanced_ options, which give you more control over the system behavior, but require you to write more code. + + +### Prerequisites + +1. Read [Concepts/Terminology](../Concepts.html) and [Architecture](../Architecture.html) +2. Read the [Quickstart guide](./Quickstart.html) to learn how Helix models and manages a cluster +3. Install Helix source. See: [Quickstart](./Quickstart.html) for the steps. + +### Tutorial Outline + +1. [Participant](./tutorial_participant.html) +2. [Spectator](./tutorial_spectator.html) +3. [Controller](./tutorial_controller.html) +4. [Rebalancing Algorithms](./tutorial_rebalance.html) +5. [User-Defined Rebalancing](./tutorial_user_def_rebalancer.html) +6. [State Machines](./tutorial_state.html) +7. [Messaging](./tutorial_messaging.html) +8. [Customized health check](./tutorial_health.html) +9. [Throttling](./tutorial_throttling.html) +10. [Application Property Store](./tutorial_propstore.html) +11. [Admin Interface](./tutorial_admin.html) +12. [YAML Cluster Setup](./tutorial_yaml.html) +13. [Helix Agent (for non-JVM systems)](./tutorial_agent.html) +14. [Task Framework](./tutorial_task_framework.html) + 1. [Task with User Defined Content Store](./tutorial_user_content_store.html) + 2. [Task Throttling](./tutorial_task_throttling.html) +15. [Helix REST Service 2.0](./tutorial_rest_service.html) +16. [Helix UI Setup](./tutorial_ui.html) + +### Preliminaries + +First, we need to set up the system. Let\'s walk through the steps in building a distributed system using Helix. + +#### Start ZooKeeper + +This starts a zookeeper in standalone mode. For production deployment, see [Apache ZooKeeper](http://zookeeper.apache.org) for instructions. + +``` +./start-standalone-zookeeper.sh 2199 & +``` + +#### Create a Cluster + +Creating a cluster will define the cluster in appropriate znodes on ZooKeeper. + +Using the Java API: + +``` +// Create setup tool instance +// Note: ZK_ADDRESS is the host:port of Zookeeper +String ZK_ADDRESS = "localhost:2199"; +admin = new ZKHelixAdmin(ZK_ADDRESS); + +String CLUSTER_NAME = "helix-demo"; +//Create cluster namespace in zookeeper +admin.addCluster(CLUSTER_NAME); +``` + +OR + +Using the command-line interface: + +``` +./helix-admin.sh --zkSvr localhost:2199 --addCluster helix-demo +``` + + +#### Configure the Nodes of the Cluster + +First we\'ll add new nodes to the cluster, then configure the nodes in the cluster. Each node in the cluster must be uniquely identifiable. +The most commonly used convention is hostname:port. + +``` +String CLUSTER_NAME = "helix-demo"; +int NUM_NODES = 2; +String hosts[] = new String[]{"localhost","localhost"}; +String ports[] = new String[]{7000,7001}; +for (int i = 0; i < NUM_NODES; i++) +{ + InstanceConfig instanceConfig = new InstanceConfig(hosts[i]+ "_" + ports[i]); + instanceConfig.setHostName(hosts[i]); + instanceConfig.setPort(ports[i]); + instanceConfig.setInstanceEnabled(true); + + //Add additional system specific configuration if needed. These can be accessed during the node start up. + instanceConfig.getRecord().setSimpleField("key", "value"); + admin.addInstance(CLUSTER_NAME, instanceConfig); +} +``` + +#### Configure the Resource + +A __resource__ represents the actual task performed by the nodes. It can be a database, index, topic, queue or any other processing entity. +A resource can be divided into many sub-parts known as __partitions__. + + +##### Define the State Model and Constraints + +For scalability and fault tolerance, each partition can have one or more replicas. +The __state model__ allows one to declare the system behavior by first enumerating the various STATES, and the TRANSITIONS between them. +A simple model is ONLINE-OFFLINE where ONLINE means the task is active and OFFLINE means it\'s not active. +You can also specify how many replicas must be in each state, these are known as __constraints__. +For example, in a search system, one might need more than one node serving the same index to handle the load. + +The allowed states: + +* MASTER +* SLAVE +* OFFLINE + +The allowed transitions: + +* OFFLINE to SLAVE +* SLAVE to OFFLINE +* SLAVE to MASTER +* MASTER to SLAVE + +The constraints: + +* no more than 1 MASTER per partition +* the rest of the replicas should be slaves + +The following snippet shows how to declare the state model and constraints for the MASTER-SLAVE model. + +``` +StateModelDefinition.Builder builder = new StateModelDefinition.Builder(STATE_MODEL_NAME); + +// Add states and their rank to indicate priority. A lower rank corresponds to a higher priority +builder.addState(MASTER, 1); +builder.addState(SLAVE, 2); +builder.addState(OFFLINE); + +// Set the initial state when the node starts +builder.initialState(OFFLINE); + +// Add transitions between the states. +builder.addTransition(OFFLINE, SLAVE); +builder.addTransition(SLAVE, OFFLINE); +builder.addTransition(SLAVE, MASTER); +builder.addTransition(MASTER, SLAVE); + +// set constraints on states + +// static constraint: upper bound of 1 MASTER +builder.upperBound(MASTER, 1); + +// dynamic constraint: R means it should be derived based on the replication factor for the cluster +// this allows a different replication factor for each resource without +// having to define a new state model + +builder.dynamicUpperBound(SLAVE, "R"); + +StateModelDefinition statemodelDefinition = builder.build(); +admin.addStateModelDef(CLUSTER_NAME, STATE_MODEL_NAME, myStateModel); +``` + +##### Assigning Partitions to Nodes + +The final goal of Helix is to ensure that the constraints on the state model are satisfied. +Helix does this by assigning a __state__ to a partition (such as MASTER, SLAVE), and placing it on a particular node. + +There are 3 assignment modes Helix can operate in: + +* FULL_AUTO: Helix decides the placement and state of a partition. +* SEMI_AUTO: Application decides the placement but Helix decides the state of a partition. +* CUSTOMIZED: Application controls the placement and state of a partition. + +For more information on the assignment modes, see the [Rebalancing Algorithms](./tutorial_rebalance.html) section of this tutorial. + +``` +String RESOURCE_NAME = "MyDB"; +int NUM_PARTITIONS = 6; +STATE_MODEL_NAME = "MasterSlave"; +String MODE = "SEMI_AUTO"; +int NUM_REPLICAS = 2; + +admin.addResource(CLUSTER_NAME, RESOURCE_NAME, NUM_PARTITIONS, STATE_MODEL_NAME, MODE); +admin.rebalance(CLUSTER_NAME, RESOURCE_NAME, NUM_REPLICAS); +```
