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From ka...@apache.org
Subject [12/16] git commit: [HELIX-270] Include documentation for previous version on the website
Date Sat, 16 Nov 2013 02:32:09 GMT
[HELIX-270] Include documentation for previous version on the website


Project: http://git-wip-us.apache.org/repos/asf/incubator-helix/repo
Commit: http://git-wip-us.apache.org/repos/asf/incubator-helix/commit/150ce693
Tree: http://git-wip-us.apache.org/repos/asf/incubator-helix/tree/150ce693
Diff: http://git-wip-us.apache.org/repos/asf/incubator-helix/diff/150ce693

Branch: refs/heads/master
Commit: 150ce693942cd7d95179c32242be6598711ad207
Parents: 9f82f6e
Author: Kanak Biscuitwala <kanak@apache.org>
Authored: Fri Nov 15 14:37:39 2013 -0800
Committer: Kanak Biscuitwala <kanak@apache.org>
Committed: Fri Nov 15 14:37:39 2013 -0800

----------------------------------------------------------------------
 pom.xml                                         |   6 +-
 .../releasenotes/release-0.6.0-incubating.apt   |  77 ---
 .../src/site/markdown/Building.md               |  46 ++
 .../0.6.1-incubating/src/site/markdown/index.md |  84 +--
 .../src/site/markdown/tutorial_messaging.md     |   2 +-
 .../src/site/markdown/tutorial_propstore.md     |   2 +-
 .../0.6.1-incubating/src/site/site.xml          |   9 +-
 site-releases/0.6.2-incubating/pom.xml          |  51 ++
 .../src/site/apt/privacy-policy.apt             |  52 ++
 .../releasenotes/release-0.6.2-incubating.apt   | 181 ++++++
 .../0.6.2-incubating/src/site/apt/releasing.apt | 107 ++++
 .../src/site/markdown/Architecture.md           | 252 ++++++++
 .../src/site/markdown/Building.md               |  46 ++
 .../src/site/markdown/Concepts.md               | 275 ++++++++
 .../src/site/markdown/Features.md               | 313 ++++++++++
 .../src/site/markdown/Quickstart.md             | 626 +++++++++++++++++++
 .../src/site/markdown/Tutorial.md               | 205 ++++++
 .../0.6.2-incubating/src/site/markdown/index.md |  58 ++
 .../src/site/markdown/recipes/lock_manager.md   | 253 ++++++++
 .../markdown/recipes/rabbitmq_consumer_group.md | 227 +++++++
 .../recipes/rsync_replicated_file_store.md      | 165 +++++
 .../site/markdown/recipes/service_discovery.md  | 191 ++++++
 .../site/markdown/recipes/task_dag_execution.md | 204 ++++++
 .../src/site/markdown/tutorial_admin.md         | 407 ++++++++++++
 .../src/site/markdown/tutorial_controller.md    |  94 +++
 .../src/site/markdown/tutorial_health.md        |  46 ++
 .../src/site/markdown/tutorial_messaging.md     |  71 +++
 .../src/site/markdown/tutorial_participant.md   | 105 ++++
 .../src/site/markdown/tutorial_propstore.md     |  34 +
 .../src/site/markdown/tutorial_rebalance.md     | 181 ++++++
 .../src/site/markdown/tutorial_spectator.md     |  76 +++
 .../src/site/markdown/tutorial_state.md         | 131 ++++
 .../src/site/markdown/tutorial_throttling.md    |  38 ++
 .../markdown/tutorial_user_def_rebalancer.md    | 172 +++++
 .../src/site/markdown/tutorial_yaml.md          | 102 +++
 .../src/site/resources/.htaccess                |  20 +
 .../src/site/resources/download.cgi             |  22 +
 .../site/resources/images/HELIX-components.png  | Bin 0 -> 82112 bytes
 .../src/site/resources/images/PFS-Generic.png   | Bin 0 -> 72435 bytes
 .../site/resources/images/RSYNC_BASED_PFS.png   | Bin 0 -> 78007 bytes
 .../resources/images/bootstrap_statemodel.gif   | Bin 0 -> 24919 bytes
 .../resources/images/helix-architecture.png     | Bin 0 -> 282390 bytes
 .../src/site/resources/images/helix-logo.jpg    | Bin 0 -> 13659 bytes
 .../resources/images/helix-znode-layout.png     | Bin 0 -> 53074 bytes
 .../src/site/resources/images/statemachine.png  | Bin 0 -> 41641 bytes
 .../src/site/resources/images/system.png        | Bin 0 -> 79791 bytes
 .../0.6.2-incubating/src/site/site.xml          | 119 ++++
 .../src/site/xdoc/download.xml.vm               | 193 ++++++
 .../0.6.2-incubating/src/test/conf/testng.xml   |  27 +
 site-releases/0.7.0-incubating/pom.xml          |  51 ++
 .../src/site/apt/privacy-policy.apt             |  52 ++
 .../releasenotes/release-0.7.0-incubating.apt   | 174 ++++++
 .../0.7.0-incubating/src/site/apt/releasing.apt | 107 ++++
 .../src/site/markdown/Architecture.md           | 252 ++++++++
 .../src/site/markdown/Building.md               |  46 ++
 .../src/site/markdown/Concepts.md               | 275 ++++++++
 .../src/site/markdown/Features.md               | 313 ++++++++++
 .../src/site/markdown/Quickstart.md             | 626 +++++++++++++++++++
 .../src/site/markdown/Tutorial.md               | 284 +++++++++
 .../src/site/markdown/UseCases.md               | 113 ++++
 .../0.7.0-incubating/src/site/markdown/index.md |  60 ++
 .../src/site/markdown/recipes/lock_manager.md   | 253 ++++++++
 .../markdown/recipes/rabbitmq_consumer_group.md | 227 +++++++
 .../recipes/rsync_replicated_file_store.md      | 165 +++++
 .../site/markdown/recipes/service_discovery.md  | 191 ++++++
 .../site/markdown/recipes/task_dag_execution.md | 204 ++++++
 .../markdown/recipes/user_def_rebalancer.md     | 285 +++++++++
 .../src/site/markdown/tutorial_accessors.md     | 125 ++++
 .../src/site/markdown/tutorial_admin.md         | 407 ++++++++++++
 .../src/site/markdown/tutorial_controller.md    |  79 +++
 .../src/site/markdown/tutorial_health.md        |  46 ++
 .../src/site/markdown/tutorial_messaging.md     |  71 +++
 .../src/site/markdown/tutorial_participant.md   |  97 +++
 .../src/site/markdown/tutorial_propstore.md     |  34 +
 .../src/site/markdown/tutorial_rebalance.md     | 181 ++++++
 .../src/site/markdown/tutorial_spectator.md     |  76 +++
 .../src/site/markdown/tutorial_state.md         | 131 ++++
 .../src/site/markdown/tutorial_throttling.md    |  38 ++
 .../markdown/tutorial_user_def_rebalancer.md    | 227 +++++++
 .../src/site/markdown/tutorial_yaml.md          | 102 +++
 .../src/site/resources/.htaccess                |  20 +
 .../src/site/resources/download.cgi             |  22 +
 .../site/resources/images/HELIX-components.png  | Bin 0 -> 82112 bytes
 .../src/site/resources/images/PFS-Generic.png   | Bin 0 -> 72435 bytes
 .../site/resources/images/RSYNC_BASED_PFS.png   | Bin 0 -> 78007 bytes
 .../resources/images/bootstrap_statemodel.gif   | Bin 0 -> 24919 bytes
 .../resources/images/helix-architecture.png     | Bin 0 -> 282390 bytes
 .../src/site/resources/images/helix-logo.jpg    | Bin 0 -> 13659 bytes
 .../resources/images/helix-znode-layout.png     | Bin 0 -> 53074 bytes
 .../src/site/resources/images/statemachine.png  | Bin 0 -> 41641 bytes
 .../src/site/resources/images/system.png        | Bin 0 -> 79791 bytes
 .../0.7.0-incubating/src/site/site.xml          | 120 ++++
 .../src/site/xdoc/download.xml.vm               | 193 ++++++
 .../0.7.0-incubating/src/test/conf/testng.xml   |  27 +
 site-releases/pom.xml                           |   3 +
 site-releases/trunk/pom.xml                     |  51 ++
 .../trunk/src/site/apt/privacy-policy.apt       |  52 ++
 site-releases/trunk/src/site/apt/releasing.apt  | 107 ++++
 .../trunk/src/site/markdown/Architecture.md     | 252 ++++++++
 .../trunk/src/site/markdown/Building.md         |  29 +
 .../trunk/src/site/markdown/Concepts.md         | 275 ++++++++
 .../trunk/src/site/markdown/Features.md         | 313 ++++++++++
 .../trunk/src/site/markdown/Quickstart.md       | 621 ++++++++++++++++++
 .../trunk/src/site/markdown/Tutorial.md         | 284 +++++++++
 .../trunk/src/site/markdown/UseCases.md         | 113 ++++
 site-releases/trunk/src/site/markdown/index.md  |  56 ++
 .../src/site/markdown/recipes/lock_manager.md   | 253 ++++++++
 .../markdown/recipes/rabbitmq_consumer_group.md | 227 +++++++
 .../recipes/rsync_replicated_file_store.md      | 165 +++++
 .../site/markdown/recipes/service_discovery.md  | 191 ++++++
 .../site/markdown/recipes/task_dag_execution.md | 204 ++++++
 .../markdown/recipes/user_def_rebalancer.md     | 285 +++++++++
 .../src/site/markdown/tutorial_accessors.md     | 125 ++++
 .../trunk/src/site/markdown/tutorial_admin.md   | 407 ++++++++++++
 .../src/site/markdown/tutorial_controller.md    |  79 +++
 .../trunk/src/site/markdown/tutorial_health.md  |  46 ++
 .../src/site/markdown/tutorial_messaging.md     |  71 +++
 .../src/site/markdown/tutorial_participant.md   |  97 +++
 .../src/site/markdown/tutorial_propstore.md     |  34 +
 .../src/site/markdown/tutorial_rebalance.md     | 181 ++++++
 .../src/site/markdown/tutorial_spectator.md     |  76 +++
 .../trunk/src/site/markdown/tutorial_state.md   | 131 ++++
 .../src/site/markdown/tutorial_throttling.md    |  38 ++
 .../markdown/tutorial_user_def_rebalancer.md    | 227 +++++++
 .../trunk/src/site/markdown/tutorial_yaml.md    | 102 +++
 .../trunk/src/site/resources/.htaccess          |  20 +
 .../trunk/src/site/resources/download.cgi       |  22 +
 .../site/resources/images/HELIX-components.png  | Bin 0 -> 82112 bytes
 .../src/site/resources/images/PFS-Generic.png   | Bin 0 -> 72435 bytes
 .../site/resources/images/RSYNC_BASED_PFS.png   | Bin 0 -> 78007 bytes
 .../resources/images/bootstrap_statemodel.gif   | Bin 0 -> 24919 bytes
 .../resources/images/helix-architecture.png     | Bin 0 -> 282390 bytes
 .../src/site/resources/images/helix-logo.jpg    | Bin 0 -> 13659 bytes
 .../resources/images/helix-znode-layout.png     | Bin 0 -> 53074 bytes
 .../src/site/resources/images/statemachine.png  | Bin 0 -> 41641 bytes
 .../trunk/src/site/resources/images/system.png  | Bin 0 -> 79791 bytes
 site-releases/trunk/src/site/site.xml           | 118 ++++
 .../trunk/src/site/xdoc/download.xml.vm         | 193 ++++++
 site-releases/trunk/src/test/conf/testng.xml    |  27 +
 .../releasenotes/release-0.6.2-incubating.apt   | 181 ++++++
 .../releasenotes/release-0.7.0-incubating.apt   | 174 ++++++
 src/site/apt/releasing.apt                      |  55 +-
 src/site/markdown/Concepts.md                   |   2 +-
 src/site/markdown/Features.md                   | 313 ----------
 src/site/markdown/Publications.md               |  37 ++
 src/site/markdown/Quickstart.md                 | 626 -------------------
 src/site/markdown/Tutorial.md                   | 205 ------
 src/site/markdown/index.md                      |  92 +--
 src/site/markdown/involved/building.md          |   6 +-
 src/site/markdown/recipes/lock_manager.md       | 253 --------
 .../markdown/recipes/rabbitmq_consumer_group.md | 227 -------
 .../recipes/rsync_replicated_file_store.md      | 165 -----
 src/site/markdown/recipes/service_discovery.md  | 191 ------
 src/site/markdown/recipes/task_dag_execution.md | 204 ------
 .../markdown/recipes/user_def_rebalancer.md     | 287 ---------
 src/site/markdown/tutorial_admin.md             | 407 ------------
 src/site/markdown/tutorial_controller.md        |  94 ---
 src/site/markdown/tutorial_health.md            |  46 --
 src/site/markdown/tutorial_messaging.md         |  71 ---
 src/site/markdown/tutorial_participant.md       | 105 ----
 src/site/markdown/tutorial_propstore.md         |  34 -
 src/site/markdown/tutorial_rebalance.md         | 181 ------
 src/site/markdown/tutorial_spectator.md         |  76 ---
 src/site/markdown/tutorial_state.md             | 131 ----
 src/site/markdown/tutorial_throttling.md        |  38 --
 .../markdown/tutorial_user_def_rebalancer.md    | 201 ------
 src/site/markdown/tutorial_yaml.md              | 102 ---
 src/site/resources/images/PFS-Generic.png       | Bin 72435 -> 0 bytes
 src/site/resources/images/RSYNC_BASED_PFS.png   | Bin 78007 -> 0 bytes
 src/site/site.xml                               |  34 +-
 170 files changed, 16738 insertions(+), 4219 deletions(-)
----------------------------------------------------------------------


http://git-wip-us.apache.org/repos/asf/incubator-helix/blob/150ce693/pom.xml
----------------------------------------------------------------------
diff --git a/pom.xml b/pom.xml
index 292ec3a..010023c 100644
--- a/pom.xml
+++ b/pom.xml
@@ -311,7 +311,7 @@ under the License.
     <helix.release.arguments>-Papache-release</helix.release.arguments>
 
     <!-- for release changelog and download pages -->
-    <currentRelease>0.6.1-incubating</currentRelease>
+    <currentRelease>0.7.0-incubating</currentRelease>
 
     <!-- OSGi Properties -->
     <osgi.import />
@@ -507,6 +507,10 @@ under the License.
             <content>${helix.siteFilePath}</content>
             <checkoutDirectory>${helix.scmPubCheckoutDirectory}</checkoutDirectory>
             <skipDeletedFiles>${scmSkipDeletedFiles}</skipDeletedFiles>
+            <ignorePathsToDelete>
+              <ignorePathToDelete>javadocs</ignorePathToDelete>
+              <ignorePathToDelete>javadocs**</ignorePathToDelete>
+            </ignorePathsToDelete>
           </configuration>
           <dependencies>
             <dependency>

http://git-wip-us.apache.org/repos/asf/incubator-helix/blob/150ce693/site-releases/0.6.1-incubating/src/site/apt/releasenotes/release-0.6.0-incubating.apt
----------------------------------------------------------------------
diff --git a/site-releases/0.6.1-incubating/src/site/apt/releasenotes/release-0.6.0-incubating.apt b/site-releases/0.6.1-incubating/src/site/apt/releasenotes/release-0.6.0-incubating.apt
deleted file mode 100644
index 16e2fbf..0000000
--- a/site-releases/0.6.1-incubating/src/site/apt/releasenotes/release-0.6.0-incubating.apt
+++ /dev/null
@@ -1,77 +0,0 @@
- -----
- Release Notes for 0.6.0-incubating Apache Helix
- -----
-
-~~ 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 0.6.0-incubating Apache Helix
-
-  The Apache Helix would like to announce the release of Apache Helix 0.6.0-incubating
-
-  This is the first release in Apache umbrella.
-
-  Helix is a generic cluster management framework used for the automatic management of partitioned, replicated and distributed resources hosted on a cluster of nodes. Helix provides the following features:
-
-  * Automatic assignment of resource/partition to nodes
-
-  * Node failure detection and recovery
-
-  * Dynamic addition of Resources
-
-  * Dynamic addition of nodes to the cluster
-
-  * Pluggable distributed state machine to manage the state of a resource via state transitions
-
-  * Automatic load balancing and throttling of transitions
-
-  []
-
-* Changes
-
-** Bug
-
- * [HELIX-1] - Use org.apache.helix package for java sources.
-
- * [HELIX-2] - Remove jsqlparser dependency from Helix
-
- * [HELIX-3] - Fix license headers in sources.
-
- * [HELIX-12] - Issue with starting multiple controllers with same name
- 
- * [HELIX-14] - error in helix-core ivy file
-
- []
-
-** Task
-
-  * [HELIX-4] - Remove deprecated file based implementation
-
-  * [HELIX-5] - Remove deprecated Accessors
-
-  * [HELIX-13] - New usecase to replicate files between replicas using simple rsync
-
-  * [HELIX-15] - Distributed lock manager recipe
-
-  []
-
-  Have Fun
-  --
-  The Apache Helix Team

http://git-wip-us.apache.org/repos/asf/incubator-helix/blob/150ce693/site-releases/0.6.1-incubating/src/site/markdown/Building.md
----------------------------------------------------------------------
diff --git a/site-releases/0.6.1-incubating/src/site/markdown/Building.md b/site-releases/0.6.1-incubating/src/site/markdown/Building.md
new file mode 100644
index 0000000..f79193e
--- /dev/null
+++ b/site-releases/0.6.1-incubating/src/site/markdown/Building.md
@@ -0,0 +1,46 @@
+<!---
+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
+------------------
+
+Requirements: Jdk 1.6+, Maven 2.0.8+
+
+```
+git clone https://git-wip-us.apache.org/repos/asf/incubator-helix.git
+cd incubator-helix
+git checkout tags/helix-0.6.1-incubating
+mvn install package -DskipTests
+```
+
+Maven dependency
+
+```
+<dependency>
+  <groupId>org.apache.helix</groupId>
+  <artifactId>helix-core</artifactId>
+  <version>0.6.1-incubating</version>
+</dependency>
+```
+
+Download
+--------
+
+[0.6.1-incubating](./download.html)
+

http://git-wip-us.apache.org/repos/asf/incubator-helix/blob/150ce693/site-releases/0.6.1-incubating/src/site/markdown/index.md
----------------------------------------------------------------------
diff --git a/site-releases/0.6.1-incubating/src/site/markdown/index.md b/site-releases/0.6.1-incubating/src/site/markdown/index.md
index 632d95c..a358d88 100644
--- a/site-releases/0.6.1-incubating/src/site/markdown/index.md
+++ b/site-releases/0.6.1-incubating/src/site/markdown/index.md
@@ -28,11 +28,13 @@ Navigating the Documentation
 
 ### Hands-on Helix
 
+[Getting Helix](./Building.html)
+
 [Quickstart](./Quickstart.html)
 
 [Tutorial](./Tutorial.html)
 
-[Javadocs](./apidocs/index.html)
+[Javadocs](http://helix.incubator.apache.org/javadocs/0.6.1-incubating/index.html)
 
 ### Recipes
 
@@ -50,83 +52,3 @@ Navigating the Documentation
 
 [0.6.1-incubating](./download.html)
 
-
-What Is Helix
---------------
-Helix is a generic _cluster management_ framework used for the automatic management of partitioned, replicated and distributed resources hosted on a cluster of nodes. 
-
-
-What Is Cluster Management
---------------------------
-To understand Helix, first you need to understand what is _cluster management_.  A distributed system typically runs on multiple nodes for the following reasons:
-
-* scalability
-* fault tolerance
-* load balancing
-
-Each node performs one or more of the primary function of the cluster, such as storing/serving data, producing/consuming data streams, etc.  Once configured for your system, Helix acts as the global brain for the system.  It is designed to make decisions that cannot be made in isolation.  Examples of decisions that require global knowledge and coordination:
-
-* scheduling of maintainence tasks, such as backups, garbage collection, file consolidation, index rebuilds
-* repartitioning of data or resources across the cluster
-* informing dependent systems of changes so they can react appropriately to cluster changes
-* throttling system tasks and changes
-
-While it is possible to integrate these functions into the distributed system, it complicates the code.  Helix has abstracted common cluster management tasks, enabling the system builder to model the desired behavior in a declarative state model, and let Helix manage the coordination.  The result is less new code to write, and a robust, highly operable system.
-
-
-Key Features of Helix
----------------------
-1. Automatic assignment of resource/partition to nodes
-2. Node failure detection and recovery
-3. Dynamic addition of Resources 
-4. Dynamic addition of nodes to the cluster
-5. Pluggable distributed state machine to manage the state of a resource via state transitions
-6. Automatic load balancing and throttling of transitions 
-
-
-Why Helix
----------
-Modeling a distributed system as a state machine with constraints on state and transitions has the following benefits:
-
-* Separates cluster management from the core functionality.
-* Quick transformation from a single node system to an operable, distributed system.
-* Simplicity: System components do not have to manage global cluster.  This division of labor makes it easier to build, debug, and maintain your system.
-
-
-Build Instructions
-------------------
-
-Requirements: Jdk 1.6+, Maven 2.0.8+
-
-```
-    git clone https://git-wip-us.apache.org/repos/asf/incubator-helix.git
-    cd incubator-helix
-    git checkout tags/helix-0.6.1-incubating
-    mvn install package -DskipTests 
-```
-
-Maven dependency
-
-```
-    <dependency>
-      <groupId>org.apache.helix</groupId>
-      <artifactId>helix-core</artifactId>
-      <version>0.6.1-incubating</version>
-    </dependency>
-```
-
-[Download](./download.html) Helix artifacts from here.
-   
-Publications
--------------
-
-* Untangling cluster management using Helix at [SOCC Oct 2012](http://www.socc2012.org/home/program)  
-    - [paper](https://915bbc94-a-62cb3a1a-s-sites.googlegroups.com/site/acm2012socc/helix_onecol.pdf)
-    - [presentation](http://www.slideshare.net/KishoreGopalakrishna/helix-socc-v10final)
-* Building distributed systems using Helix Apache Con Feb 2013
-    - [presentation at ApacheCon](http://www.slideshare.net/KishoreGopalakrishna/apache-con-buildingddsusinghelix)
-    - [presentation at VMWare](http://www.slideshare.net/KishoreGopalakrishna/apache-helix-presentation-at-vmware)
-* Data driven testing:
-    - [short talk at LSPE meetup](http://www.slideshare.net/KishoreGopalakrishna/data-driven-testing)
-    - [paper DBTest 2013 acm SIGMOD:will be published on Jun 24, 2013](http://dbtest2013.soe.ucsc.edu/Program.htm)
-

http://git-wip-us.apache.org/repos/asf/incubator-helix/blob/150ce693/site-releases/0.6.1-incubating/src/site/markdown/tutorial_messaging.md
----------------------------------------------------------------------
diff --git a/site-releases/0.6.1-incubating/src/site/markdown/tutorial_messaging.md b/site-releases/0.6.1-incubating/src/site/markdown/tutorial_messaging.md
index 2dda826..4b46671 100644
--- a/site-releases/0.6.1-incubating/src/site/markdown/tutorial_messaging.md
+++ b/site-releases/0.6.1-incubating/src/site/markdown/tutorial_messaging.md
@@ -63,5 +63,5 @@ System Admins can also perform ad-hoc tasks, such as on-demand backups or a syst
           requestBackupUriRequest, responseHandler, timeout);
 ```
 
-See HelixManager.DefaultMessagingService in [Javadocs](./apidocs/reference/org/apache/helix/messaging/DefaultMessagingService.html) for more info.
+See HelixManager.DefaultMessagingService in [Javadocs](http://helix.incubator.apache.org/javadocs/0.6.1-incubating/reference/org/apache/helix/messaging/DefaultMessagingService.html) for more info.
 

http://git-wip-us.apache.org/repos/asf/incubator-helix/blob/150ce693/site-releases/0.6.1-incubating/src/site/markdown/tutorial_propstore.md
----------------------------------------------------------------------
diff --git a/site-releases/0.6.1-incubating/src/site/markdown/tutorial_propstore.md b/site-releases/0.6.1-incubating/src/site/markdown/tutorial_propstore.md
index af3c60d..4ee9299 100644
--- a/site-releases/0.6.1-incubating/src/site/markdown/tutorial_propstore.md
+++ b/site-releases/0.6.1-incubating/src/site/markdown/tutorial_propstore.md
@@ -27,4 +27,4 @@ It is common that an application needs support for distributed, shared data stru
 
 While you could use Zookeeper directly, Helix supports caching the data and a write-through cache. This is far more efficient than reading from Zookeeper for every access.
 
-See [HelixManager.getHelixPropertyStore](./apidocs/reference/org/apache/helix/store/package-summary.html) for details.
+See [HelixManager.getHelixPropertyStore](http://helix.incubator.apache.org/javadocs/0.6.1-incubating/reference/org/apache/helix/store/package-summary.html) for details.

http://git-wip-us.apache.org/repos/asf/incubator-helix/blob/150ce693/site-releases/0.6.1-incubating/src/site/site.xml
----------------------------------------------------------------------
diff --git a/site-releases/0.6.1-incubating/src/site/site.xml b/site-releases/0.6.1-incubating/src/site/site.xml
index 5ab7f87..7326162 100644
--- a/site-releases/0.6.1-incubating/src/site/site.xml
+++ b/site-releases/0.6.1-incubating/src/site/site.xml
@@ -58,13 +58,18 @@
       <item name="Release 0.6.1-incubating" href="http://helix.incubator.apache.org/site-releases/0.6.1-incubating-site/"/>
     </breadcrumbs>
 
-    <menu name="Helix 0.6.1-incubating">
+    <menu name="Apache Helix">
       <item name="Home" href="../../index.html"/>
+    </menu>
+
+    <menu name="Helix 0.6.1-incubating">
       <item name="Introduction" href="./index.html"/>
+      <item name="Getting Helix" href="./Building.html"/>
       <item name="Core concepts" href="./Concepts.html"/>
       <item name="Architecture" href="./Architecture.html"/>
       <item name="Quick Start" href="./Quickstart.html"/>
       <item name="Tutorial" href="./Tutorial.html"/>
+      <item name="Release Notes" href="releasenotes/release-0.6.1-incubating.html"/>
       <item name="Download" href="./download.html"/>
     </menu>
 
@@ -101,7 +106,7 @@
     <fluidoSkin>
       <topBarEnabled>true</topBarEnabled>
       <!-- twitter link work only with sidebar disabled -->
-      <sideBarEnabled>false</sideBarEnabled>
+      <sideBarEnabled>true</sideBarEnabled>
       <googleSearch></googleSearch>
       <twitter>
         <user>ApacheHelix</user>

http://git-wip-us.apache.org/repos/asf/incubator-helix/blob/150ce693/site-releases/0.6.2-incubating/pom.xml
----------------------------------------------------------------------
diff --git a/site-releases/0.6.2-incubating/pom.xml b/site-releases/0.6.2-incubating/pom.xml
new file mode 100644
index 0000000..471ea4c
--- /dev/null
+++ b/site-releases/0.6.2-incubating/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>site-releases</artifactId>
+    <version>0.7.1-incubating-SNAPSHOT</version>
+  </parent>
+
+  <artifactId>0.6.2-incubating-site</artifactId>
+  <packaging>bundle</packaging>
+  <name>Apache Helix :: Site :: 0.6.2-incubating</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/incubator-helix/blob/150ce693/site-releases/0.6.2-incubating/src/site/apt/privacy-policy.apt
----------------------------------------------------------------------
diff --git a/site-releases/0.6.2-incubating/src/site/apt/privacy-policy.apt b/site-releases/0.6.2-incubating/src/site/apt/privacy-policy.apt
new file mode 100644
index 0000000..ada9363
--- /dev/null
+++ b/site-releases/0.6.2-incubating/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/incubator-helix/blob/150ce693/site-releases/0.6.2-incubating/src/site/apt/releasenotes/release-0.6.2-incubating.apt
----------------------------------------------------------------------
diff --git a/site-releases/0.6.2-incubating/src/site/apt/releasenotes/release-0.6.2-incubating.apt b/site-releases/0.6.2-incubating/src/site/apt/releasenotes/release-0.6.2-incubating.apt
new file mode 100644
index 0000000..51afc62
--- /dev/null
+++ b/site-releases/0.6.2-incubating/src/site/apt/releasenotes/release-0.6.2-incubating.apt
@@ -0,0 +1,181 @@
+ -----
+ Release Notes for Apache Helix 0.6.2-incubating
+ -----
+
+~~ 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 0.6.2-incubating
+
+  The Apache Helix team would like to announce the release of Apache Helix 0.6.2-incubating
+
+  This is the third release under the Apache umbrella.
+
+  Helix is a generic cluster management framework used for the automatic management of partitioned, replicated and distributed resources hosted on a cluster of nodes. Helix provides the following features:
+
+  * Automatic assignment of resource/partition to nodes
+
+  * Node failure detection and recovery
+
+  * Dynamic addition of Resources
+
+  * Dynamic addition of nodes to the cluster
+
+  * Pluggable distributed state machine to manage the state of a resource via state transitions
+
+  * Automatic load balancing and throttling of transitions
+
+  []
+
+* Changes
+
+** Sub-task
+
+  * [HELIX-28] - ZkHelixManager.handleNewSession() can happen when a liveinstance already exists
+
+  * [HELIX-85] - Remove mock service module
+
+  * [HELIX-106] - Remove all string constants in the code
+
+  * [HELIX-107] - Add support to set custom objects into ZNRecord
+
+  * [HELIX-124] - race condition in ZkHelixManager.handleNewSession()
+
+  * [HELIX-165] - Add dependency for Guava libraries
+
+  * [HELIX-169] - Take care of consecutive handleNewSession() and session expiry during handleNewSession() 
+
+  * [HELIX-170] - HelixManager#isLeader() should compare both instanceName and sessionId 
+
+  * [HELIX-195] - Race condition between FINALIZE callbacks and Zk Callbacks
+
+  * [HELIX-207] - Add javadocs to classes and public methods in the top-level package
+
+  * [HELIX-208] - Add javadocs to classes and public methods in the model package
+
+  * [HELIX-277] - FULL_AUTO rebalancer should not prefer nodes that are just coming up
+
+** Bug
+
+  * [HELIX-7] - Tune test parameters to fix random test failures
+
+  * [HELIX-87] - Bad repository links in website
+
+  * [HELIX-117] - backward incompatibility problem in accessing zkPath vis HelixWebAdmin
+
+  * [HELIX-118] - PropertyStore -> HelixPropertyStore backwards incompatible location
+
+  * [HELIX-119] - HelixManager serializer no longer needs ByteArraySerializer for /PROPERTYSTORE
+
+  * [HELIX-129] - ZKDumper should use byte[] instead of String to read/write file/zk
+
+  * [HELIX-131] - Connection timeout not set while connecting to zookeeper via zkHelixAdmin
+
+  * [HELIX-133] - Cluster-admin command parsing does not work with removeConfig
+
+  * [HELIX-140] - In ClusterSetup.java, the removeConfig is wrong wired to getConfig
+
+  * [HELIX-141] - Autorebalance does not work reliably and fails when replica>1
+
+  * [HELIX-144] - Need to validate StateModelDefinition when adding new StateModelDefinition to Cluster
+
+  * [HELIX-147] - Fix typo in Idealstate property max_partitions_per_instance
+
+  * [HELIX-148] - Current preferred placement for auto rebalace is suboptimal for n > p
+
+  * [HELIX-150] - Auto rebalance might not evenly distribute states across nodes
+
+  * [HELIX-151] - Auto rebalance doesn't assign some replicas when other nodes could make room
+
+  * [HELIX-153] - Auto rebalance tester uses the returned map fields, but production uses only list fields
+
+  * [HELIX-155] - PropertyKey.instances() is wrongly wired to CONFIG type instead of INSTANCES type
+
+  * [HELIX-197] - state model leak
+
+  * [HELIX-199] - ZNRecord should not publish rawPayload unless it exists
+
+  * [HELIX-216] - Allow HelixAdmin addResource to accept the old rebalancing types
+
+  * [HELIX-221] - Can't find default error->dropped transition method using name convention
+
+  * [HELIX-257] - Upgrade Restlet to 2.1.4 - due security flaw
+
+  * [HELIX-258] - Upgrade Apache Camel due to CVE-2013-4330
+
+  * [HELIX-264] - fix zkclient#close() bug
+
+  * [HELIX-279] - Apply gc handling fixes to main ZKHelixManager class
+
+  * [HELIX-280] - Full auto rebalancer should check for resource tag first
+
+  * [HELIX-288] - helix-core uses an old version of guava
+
+  * [HELIX-299] - Some files in 0.6.2 are missing license headers
+
+** Improvement
+
+  * [HELIX-20] - AUTO-REBALANCE helix controller should re-assign disabled partitions on a node to other available nodes
+
+  * [HELIX-70] - Make Helix OSGi ready
+
+  * [HELIX-149] - Allow clients to pass in preferred placement strategies
+
+  * [HELIX-198] - Unify helix code style
+
+  * [HELIX-218] - Add a reviewboard submission script
+
+  * [HELIX-284] - Support participant auto join in YAML cluster setup
+
+** New Feature
+
+  * [HELIX-215] - Allow setting up the cluster with a YAML file
+
+** Task
+
+  * [HELIX-95] - Tracker for 0.6.2 release
+
+  * [HELIX-154] - Auto rebalance algorithm should not depend on state
+
+  * [HELIX-166] - Rename modes to auto, semi-auto, and custom
+
+  * [HELIX-173] - Move rebalancing strategies to separate classes that implement the Rebalancer interface
+
+  * [HELIX-188] - Add admin command line / REST API documentations
+
+  * [HELIX-194] - ZNRecord has too many constructors
+
+  * [HELIX-205] - Have user-defined rebalancers use RebalanceMode.USER_DEFINED
+
+  * [HELIX-210] - Add support to set data with expect version in BaseDataAccessor
+
+  * [HELIX-217] - Remove mock service module
+
+  * [HELIX-273] - Rebalancer interface should remain unchanged in 0.6.2
+
+  * [HELIX-274] - Verify FULL_AUTO tagged node behavior
+
+  * [HELIX-285] - add integration test util's
+
+  []
+
+  Cheers,
+  --
+  The Apache Helix Team

http://git-wip-us.apache.org/repos/asf/incubator-helix/blob/150ce693/site-releases/0.6.2-incubating/src/site/apt/releasing.apt
----------------------------------------------------------------------
diff --git a/site-releases/0.6.2-incubating/src/site/apt/releasing.apt b/site-releases/0.6.2-incubating/src/site/apt/releasing.apt
new file mode 100644
index 0000000..11d0cd9
--- /dev/null
+++ b/site-releases/0.6.2-incubating/src/site/apt/releasing.apt
@@ -0,0 +1,107 @@
+ -----
+ Helix release process
+ -----
+ -----
+ 2012-12-15
+ -----
+
+~~ 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
+
+Helix release process
+
+ [[1]] Post to the dev list a few days before you plan to do an Helix release
+
+ [[2]] Your maven setting must contains the entry to be able to deploy.
+
+ ~/.m2/settings.xml
+
++-------------
+   <server>
+     <id>apache.releases.https</id>
+     <username></username>
+     <password></password>
+   </server>
++-------------
+
+ [[3]] Apache DAV passwords
+
++-------------
+ Add the following info into your ~/.netrc
+ machine git-wip-us.apache.org login <apache username> <password>
+
++-------------
+ [[4]] Release Helix
+    You should have a GPG agent running in the session you will run the maven release commands(preferred), and confirm it works by running "gpg -ab" (type some text and press Ctrl-D).
+    If you do not have a GPG agent running, make sure that you have the "apache-release" profile set in your settings.xml as shown below.
+
+   Run the release
+
++-------------
+mvn release:prepare release:perform -B
++-------------
+
+  GPG configuration in maven settings xml:
+
++-------------
+<profile>
+  <id>apache-release</id>
+  <properties>
+    <gpg.passphrase>[GPG_PASSWORD]</gpg.passphrase>
+  </properties>
+</profile>
++-------------
+
+ [[4]] go to https://repository.apache.org and close your staged repository. Note the repository url (format https://repository.apache.org/content/repositories/orgapachehelix-019/org/apache/helix/helix/0.6-incubating/)
+
++-------------
+svn co https://dist.apache.org/repos/dist/dev/incubator/helix helix-dev-release
+cd helix-dev-release
+sh ./release-script-svn.sh version stagingRepoUrl
+then svn add <new directory created with new version as name>
+then svn ci 
++-------------
+
+ [[5]] Validating the release
+
++-------------
+  * Download sources, extract, build and run tests - mvn clean package
+  * Verify license headers - mvn -Prat -DskipTests
+  * Download binaries and .asc files
+  * Download release manager's public key - From the KEYS file, get the release manager's public key finger print and run  gpg --keyserver pgpkeys.mit.edu --recv-key <key>
+  * Validate authenticity of key - run  gpg --fingerprint <key>
+  * Check signatures of all the binaries using gpg <binary>
++-------------
+
+ [[6]] Call for a vote in the dev list and wait for 72 hrs. for the vote results. 3 binding votes are necessary for the release to be finalized. example
+  After the vote has passed, move the files from dist dev to dist release: svn mv https://dist.apache.org/repos/dist/dev/incubator/helix/version to https://dist.apache.org/repos/dist/release/incubator/helix/
+
+ [[7]] Prepare release note. Add a page in src/site/apt/releasenotes/ and change value of \<currentRelease> in parent pom.
+
+
+ [[8]] Send out an announcement of the release to:
+
+  * users@helix.incubator.apache.org
+
+  * dev@helix.incubator.apache.org
+
+ [[9]] Celebrate !
+
+

http://git-wip-us.apache.org/repos/asf/incubator-helix/blob/150ce693/site-releases/0.6.2-incubating/src/site/markdown/Architecture.md
----------------------------------------------------------------------
diff --git a/site-releases/0.6.2-incubating/src/site/markdown/Architecture.md b/site-releases/0.6.2-incubating/src/site/markdown/Architecture.md
new file mode 100644
index 0000000..933e917
--- /dev/null
+++ b/site-releases/0.6.2-incubating/src/site/markdown/Architecture.md
@@ -0,0 +1,252 @@
+<!---
+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>Architecture</title>
+</head>
+
+Architecture
+----------------------------
+Helix aims to provide the following abilities to a distributed system:
+
+* Automatic management of a cluster hosting partitioned, replicated resources.
+* Soft and hard failure detection and handling.
+* Automatic load balancing via smart placement of resources on servers(nodes) based on server capacity and resource profile (size of partition, access patterns, etc).
+* Centralized config management and self discovery. Eliminates the need to modify config on each node.
+* Fault tolerance and optimized rebalancing during cluster expansion.
+* Manages entire operational lifecycle of a node. Addition, start, stop, enable/disable without downtime.
+* Monitor cluster health and provide alerts on SLA violation.
+* Service discovery mechanism to route requests.
+
+To build such a system, we need a mechanism to co-ordinate between different nodes and other components in the system. This mechanism can be achieved with software that reacts to any change in the cluster and comes up with a set of tasks needed to bring the cluster to a stable state. The set of tasks will be assigned to one or more nodes in the cluster. Helix serves this purpose of managing the various components in the cluster.
+
+![Helix Design](images/system.png)
+
+Distributed System Components
+
+In general any distributed system cluster will have the following components and properties:
+
+* A set of nodes also referred to as instances.
+* A set of resources which can be databases, lucene indexes or tasks.
+* Each resource is also partitioned into one or more Partitions. 
+* Each partition may have one or more copies called replicas.
+* Each replica can have a state associated with it. For example Master, Slave, Leader, Standby, Online, Offline etc
+
+Roles
+-----
+
+![Helix Design](images/HELIX-components.png)
+
+Not all nodes in a distributed system will perform similar functionalities. For example, a few nodes might be serving requests and a few nodes might be sending requests, and some nodes might be controlling the nodes in the cluster. Thus, Helix categorizes nodes by their specific roles in the system.
+
+We have divided Helix nodes into 3 logical components based on their responsibilities:
+
+1. Participant: The nodes that actually host the distributed resources.
+2. Spectator: The nodes that simply observe the Participant state and route the request accordingly. Routers, for example, need to know the instance on which a partition is hosted and its state in order to route the request to the appropriate end point.
+3. Controller: The controller observes and controls the Participant nodes. It is responsible for coordinating all transitions in the cluster and ensuring that state constraints are satisfied and cluster stability is maintained. 
+
+These are simply logical components and can be deployed as per the system requirements. For example:
+
+1. The controller can be deployed as a separate service
+2. The controller can be deployed along with a Participant but only one Controller will be active at any given time.
+
+Both have pros and cons, which will be discussed later and one can chose the mode of deployment as per system needs.
+
+
+## Cluster state metadata store
+
+We need a distributed store to maintain the state of the cluster and a notification system to notify if there is any change in the cluster state. Helix uses Zookeeper to achieve this functionality.
+
+Zookeeper provides:
+
+* A way to represent PERSISTENT state which basically remains until its deleted.
+* A way to represent TRANSIENT/EPHEMERAL state which vanishes when the process that created the state dies.
+* Notification mechanism when there is a change in PERSISTENT and EPHEMERAL state
+
+The namespace provided by ZooKeeper is much like that of a standard file system. A name is a sequence of path elements separated by a slash (/). Every node[ZNode] in ZooKeeper\'s namespace is identified by a path.
+
+More info on Zookeeper can be found at http://zookeeper.apache.org
+
+## State machine and constraints
+
+Even though the concepts of Resources, Partitions, and Replicas are common to most distributed systems, one thing that differentiates one distributed system from another is the way each partition is assigned a state and the constraints on each state.
+
+For example:
+
+1. If a system is serving read-only data then all partition\'s replicas are equal and they can either be ONLINE or OFFLINE.
+2. If a system takes _both_ reads and writes but ensure that writes go through only one partition, the states will be MASTER, SLAVE, and OFFLINE. Writes go through the MASTER and replicate to the SLAVEs. Optionally, reads can go through SLAVES.
+
+Apart from defining state for each partition, the transition path to each state can be application specific. For example, in order to become MASTER it might be a requirement to first become a SLAVE. This ensures that if the SLAVE does not have the data as part of OFFLINE-SLAVE transition it can bootstrap data from other nodes in the system.
+
+Helix provides a way to configure an application specific state machine along with constraints on each state. Along with constraints on STATE, Helix also provides a way to specify constraints on transitions.  (More on this later.)
+
+```
+          OFFLINE  | SLAVE  |  MASTER  
+         _____________________________
+        |          |        |         |
+OFFLINE |   N/A    | SLAVE  | SLAVE   |
+        |__________|________|_________|
+        |          |        |         |
+SLAVE   |  OFFLINE |   N/A  | MASTER  |
+        |__________|________|_________|
+        |          |        |         |
+MASTER  | SLAVE    | SLAVE  |   N/A   |
+        |__________|________|_________|
+
+```
+
+![Helix Design](images/statemachine.png)
+
+## Concepts
+
+The following terminologies are used in Helix to model a state machine.
+
+* IdealState: The state in which we need the cluster to be in if all nodes are up and running. In other words, all state constraints are satisfied.
+* CurrentState: Represents the actual current state of each node in the cluster 
+* ExternalView: Represents the combined view of CurrentState of all nodes.  
+
+The goal of Helix is always to make the CurrentState of the system same as the IdealState. Some scenarios where this may not be true are:
+
+* When all nodes are down
+* When one or more nodes fail
+* New nodes are added and the partitions need to be reassigned
+
+### IdealState
+
+Helix lets the application define the IdealState on a resource basis which basically consists of:
+
+* List of partitions. Example: 64
+* Number of replicas for each partition. Example: 3
+* Node and State for each replica.
+
+Example:
+
+* Partition-1, replica-1, Master, Node-1
+* Partition-1, replica-2, Slave, Node-2
+* Partition-1, replica-3, Slave, Node-3
+* .....
+* .....
+* Partition-p, replica-3, Slave, Node-n
+
+Helix comes with various algorithms to automatically assign the partitions to nodes. The default algorithm minimizes the number of shuffles that happen when new nodes are added to the system.
+
+### CurrentState
+
+Every instance in the cluster hosts one or more partitions of a resource. Each of the partitions has a state associated with it.
+
+Example Node-1
+
+* Partition-1, Master
+* Partition-2, Slave
+* ....
+* ....
+* Partition-p, Slave
+
+### ExternalView
+
+External clients needs to know the state of each partition in the cluster and the Node hosting that partition. Helix provides one view of the system to Spectators as _ExternalView_. ExternalView is simply an aggregate of all node CurrentStates.
+
+* Partition-1, replica-1, Master, Node-1
+* Partition-1, replica-2, Slave, Node-2
+* Partition-1, replica-3, Slave, Node-3
+* .....
+* .....
+* Partition-p, replica-3, Slave, Node-n
+
+## Process Workflow
+
+Mode of operation in a cluster
+
+A node process can be one of the following:
+
+* Participant: The process registers itself in the cluster and acts on the messages received in its queue and updates the current state.  Example: a storage node in a distributed database
+* Spectator: The process is simply interested in the changes in the Externalview.
+* Controller: This process actively controls the cluster by reacting to changes in cluster state and sending messages to Participants.
+
+
+### Participant Node Process
+
+* When Node starts up, it registers itself under _LiveInstances_
+* After registering, it waits for new _Messages_ in the message queue
+* When it receives a message, it will perform the required task as indicated in the message
+* After the task is completed, depending on the task outcome it updates the CurrentState
+
+### Controller Process
+
+* Watches IdealState
+* Notified when a node goes down/comes up or node is added/removed. Watches LiveInstances and CurrentState of each node in the cluster
+* Triggers appropriate state transitions by sending message to Participants
+
+### Spectator Process
+
+* When the process starts, it asks the Helix agent to be notified of changes in ExternalView
+* Whenever it receives a notification, it reads the Externalview and performs required duties.
+
+#### Interaction between controller, participant and spectator
+
+The following picture shows how controllers, participants and spectators interact with each other.
+
+![Helix Architecture](images/helix-architecture.png)
+
+## Core algorithm
+
+* Controller gets the IdealState and the CurrentState of active storage nodes from Zookeeper
+* Compute the delta between IdealState and CurrentState for each partition across all participant nodes
+* For each partition compute tasks based on the State Machine Table. It\'s possible to configure priority on the state Transition. For example, in case of Master-Slave:
+    * Attempt mastership transfer if possible without violating constraint.
+    * Partition Addition
+    * Drop Partition 
+* Add the tasks in parallel if possible to the respective queue for each storage node (if the tasks added are mutually independent)
+* If a task is dependent on another task being completed, do not add that task
+* After any task is completed by a Participant, Controllers gets notified of the change and the State Transition algorithm is re-run until the CurrentState is same as IdealState.
+
+## Helix ZNode layout
+
+Helix organizes znodes under clusterName in multiple levels. 
+
+The top level (under the cluster name) ZNodes are all Helix-defined and in upper case:
+
+* PROPERTYSTORE: application property store
+* STATEMODELDEFES: state model definitions
+* INSTANCES: instance runtime information including current state and messages
+* CONFIGS: configurations
+* IDEALSTATES: ideal states
+* EXTERNALVIEW: external views
+* LIVEINSTANCES: live instances
+* CONTROLLER: cluster controller runtime information
+
+Under INSTANCES, there are runtime ZNodes for each instance. An instance organizes ZNodes as follows:
+
+* CURRENTSTATES
+    * sessionId
+    * resourceName
+* ERRORS
+* STATUSUPDATES
+* MESSAGES
+* HEALTHREPORT
+
+Under CONFIGS, there are different scopes of configurations:
+
+* RESOURCE: contains resource scope configurations
+* CLUSTER: contains cluster scope configurations
+* PARTICIPANT: contains participant scope configurations
+
+The following image shows an example of Helix znodes layout for a cluster named "test-cluster":
+
+![Helix znode layout](images/helix-znode-layout.png)

http://git-wip-us.apache.org/repos/asf/incubator-helix/blob/150ce693/site-releases/0.6.2-incubating/src/site/markdown/Building.md
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+<!---
+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
+------------------
+
+Requirements: Jdk 1.6+, Maven 2.0.8+
+
+```
+git clone https://git-wip-us.apache.org/repos/asf/incubator-helix.git
+cd incubator-helix
+git checkout tags/helix-0.6.2-incubating
+mvn install package -DskipTests
+```
+
+Maven dependency
+
+```
+<dependency>
+  <groupId>org.apache.helix</groupId>
+  <artifactId>helix-core</artifactId>
+  <version>0.6.2-incubating</version>
+</dependency>
+```
+
+Download
+--------
+
+[0.6.2-incubating](./download.html)
+

http://git-wip-us.apache.org/repos/asf/incubator-helix/blob/150ce693/site-releases/0.6.2-incubating/src/site/markdown/Concepts.md
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+<!---
+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>Concepts</title>
+</head>
+
+Concepts
+----------------------------
+
+Helix is based on the idea that a given task has the following attributes associated with it:
+
+* _Location of the task_. For example it runs on Node N1
+* _State_. For example, it is running, stopped etc.
+
+In Helix terminology, a task is referred to as a _resource_.
+
+### IdealState
+
+IdealState simply allows one to map tasks to location and state. A standard way of expressing this in Helix:
+
+```
+  "TASK_NAME" : {
+    "LOCATION" : "STATE"
+  }
+
+```
+Consider a simple case where you want to launch a task \'myTask\' on node \'N1\'. The IdealState for this can be expressed as follows:
+
+```
+{
+  "id" : "MyTask",
+  "mapFields" : {
+    "myTask" : {
+      "N1" : "ONLINE",
+    }
+  }
+}
+```
+### Partition
+
+If this task get too big to fit on one box, you might want to divide it into subtasks. Each subtask is referred to as a _partition_ in Helix. Let\'s say you want to divide the task into 3 subtasks/partitions, the IdealState can be changed as shown below. 
+
+\'myTask_0\', \'myTask_1\', \'myTask_2\' are logical names representing the partitions of myTask. Each tasks runs on N1, N2 and N3 respectively.
+
+```
+{
+  "id" : "myTask",
+  "simpleFields" : {
+    "NUM_PARTITIONS" : "3",
+  }
+ "mapFields" : {
+    "myTask_0" : {
+      "N1" : "ONLINE",
+    },
+    "myTask_1" : {
+      "N2" : "ONLINE",
+    },
+    "myTask_2" : {
+      "N3" : "ONLINE",
+    }
+  }
+}
+```
+
+### Replica
+
+Partitioning allows one to split the data/task into multiple subparts. But let\'s say the request rate for each partition increases. The common solution is to have multiple copies for each partition. Helix refers to the copy of a partition as a _replica_.  Adding a replica also increases the availability of the system during failures. One can see this methodology employed often in search systems. The index is divided into shards, and each shard has multiple copies.
+
+Let\'s say you want to add one additional replica for each task. The IdealState can simply be changed as shown below. 
+
+For increasing the availability of the system, it\'s better to place the replica of a given partition on different nodes.
+
+```
+{
+  "id" : "myIndex",
+  "simpleFields" : {
+    "NUM_PARTITIONS" : "3",
+    "REPLICAS" : "2",
+  },
+ "mapFields" : {
+    "myIndex_0" : {
+      "N1" : "ONLINE",
+      "N2" : "ONLINE"
+    },
+    "myIndex_1" : {
+      "N2" : "ONLINE",
+      "N3" : "ONLINE"
+    },
+    "myIndex_2" : {
+      "N3" : "ONLINE",
+      "N1" : "ONLINE"
+    }
+  }
+}
+```
+
+### State 
+
+Now let\'s take a slightly more complicated scenario where a task represents a database.  Unlike an index which is in general read-only, a database supports both reads and writes. Keeping the data consistent among the replicas is crucial in distributed data stores. One commonly applied technique is to assign one replica as the MASTER and remaining replicas as SLAVEs. All writes go to the MASTER and are then replicated to the SLAVE replicas.
+
+Helix allows one to assign different states to each replica. Let\'s say you have two MySQL instances N1 and N2, where one will serve as MASTER and another as SLAVE. The IdealState can be changed to:
+
+```
+{
+  "id" : "myDB",
+  "simpleFields" : {
+    "NUM_PARTITIONS" : "1",
+    "REPLICAS" : "2",
+  },
+  "mapFields" : {
+    "myDB" : {
+      "N1" : "MASTER",
+      "N2" : "SLAVE",
+    }
+  }
+}
+
+```
+
+
+### State Machine and Transitions
+
+IdealState allows one to exactly specify the desired state of the cluster. Given an IdealState, Helix takes up the responsibility of ensuring that the cluster reaches the IdealState.  The Helix _controller_ reads the IdealState and then commands each Participant to take appropriate actions to move from one state to another until it matches the IdealState.  These actions are referred to as _transitions_ in Helix.
+
+The next logical question is:  how does the _controller_ compute the transitions required to get to IdealState?  This is where the finite state machine concept comes in. Helix allows applications to plug in a finite state machine.  A state machine consists of the following:
+
+* State: Describes the role of a replica
+* Transition: An action that allows a replica to move from one state to another, thus changing its role.
+
+Here is an example of MasterSlave state machine:
+
+```
+          OFFLINE  | SLAVE  |  MASTER  
+         _____________________________
+        |          |        |         |
+OFFLINE |   N/A    | SLAVE  | SLAVE   |
+        |__________|________|_________|
+        |          |        |         |
+SLAVE   |  OFFLINE |   N/A  | MASTER  |
+        |__________|________|_________|
+        |          |        |         |
+MASTER  | SLAVE    | SLAVE  |   N/A   |
+        |__________|________|_________|
+
+```
+
+Helix allows each resource to be associated with one state machine. This means you can have one resource as an index and another as a database in the same cluster. One can associate each resource with a state machine as follows:
+
+```
+{
+  "id" : "myDB",
+  "simpleFields" : {
+    "NUM_PARTITIONS" : "1",
+    "REPLICAS" : "2",
+    "STATE_MODEL_DEF_REF" : "MasterSlave",
+  },
+  "mapFields" : {
+    "myDB" : {
+      "N1" : "MASTER",
+      "N2" : "SLAVE",
+    }
+  }
+}
+
+```
+
+### Current State
+
+CurrentState of a resource simply represents its actual state at a Participant. In the below example:
+
+* INSTANCE_NAME: Unique name representing the process
+* SESSION_ID: ID that is automatically assigned every time a process joins the cluster
+
+```
+{
+  "id":"MyResource"
+  ,"simpleFields":{
+    ,"SESSION_ID":"13d0e34675e0002"
+    ,"INSTANCE_NAME":"node1"
+    ,"STATE_MODEL_DEF":"MasterSlave"
+  }
+  ,"mapFields":{
+    "MyResource_0":{
+      "CURRENT_STATE":"SLAVE"
+    }
+    ,"MyResource_1":{
+      "CURRENT_STATE":"MASTER"
+    }
+    ,"MyResource_2":{
+      "CURRENT_STATE":"MASTER"
+    }
+  }
+}
+```
+Each node in the cluster has its own CurrentState.
+
+### External View
+
+In order to communicate with the Participants, external clients need to know the current state of each of the Participants. The external clients are referred to as Spectators. In order to make the life of Spectator simple, Helix provides an ExternalView that is an aggregated view of the current state across all nodes. The ExternalView has a similar format as IdealState.
+
+```
+{
+  "id":"MyResource",
+  "mapFields":{
+    "MyResource_0":{
+      "N1":"SLAVE",
+      "N2":"MASTER",
+      "N3":"OFFLINE"
+    },
+    "MyResource_1":{
+      "N1":"MASTER",
+      "N2":"SLAVE",
+      "N3":"ERROR"
+    },
+    "MyResource_2":{
+      "N1":"MASTER",
+      "N2":"SLAVE",
+      "N3":"SLAVE"
+    }
+  }
+}
+```
+
+### Rebalancer
+
+The core component of Helix is the Controller which runs the Rebalancer algorithm on every cluster event. Cluster events can be one of the following:
+
+* Nodes start/stop and soft/hard failures
+* New nodes are added/removed
+* Ideal state changes
+
+There are few more examples such as configuration changes, etc.  The key takeaway: there are many ways to trigger the rebalancer.
+
+When a rebalancer is run it simply does the following:
+
+* Compares the IdealState and current state
+* Computes the transitions required to reach the IdealState
+* Issues the transitions to each Participant
+
+The above steps happen for every change in the system. Once the current state matches the IdealState, the system is considered stable which implies \'IdealState = CurrentState = ExternalView\'
+
+### Dynamic IdealState
+
+One of the things that makes Helix powerful is that IdealState can be changed dynamically. This means one can listen to cluster events like node failures and dynamically change the ideal state. Helix will then take care of triggering the respective transitions in the system.
+
+Helix comes with a few algorithms to automatically compute the IdealState based on the constraints. For example, if you have a resource of 3 partitions and 2 replicas, Helix can automatically compute the IdealState based on the nodes that are currently active. See the [tutorial](./tutorial_rebalance.html) to find out more about various execution modes of Helix like FULL_AUTO, SEMI_AUTO and CUSTOMIZED. 
+
+
+
+
+
+
+
+
+
+
+
+

http://git-wip-us.apache.org/repos/asf/incubator-helix/blob/150ce693/site-releases/0.6.2-incubating/src/site/markdown/Features.md
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+<!---
+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. 
+
+
+
+
+
+
+
+ 


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