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Date: Wed, 26 Oct 2011 14:23:33 +0000 (UTC)
From: "Justin Joseph (Commented) (JIRA)" <jira@apache.org>
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Subject: [jira] [Commented] (HDFS-2354) Generalize the HAServiceProtocol
 interface
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    [ https://issues.apache.org/jira/browse/HDFS-2354?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13136011#comment-13136011 ] 

Justin Joseph commented on HDFS-2354:
-------------------------------------

bq. Can you explain hot it is against the goal of HDFS-1623?

HDFS-1623 aims to build a framework for HA, where there is room for multiple approaches for HA (Shared Storage / Backup Node Based, Zookeeper / Linux HA, IP failover / Intelligent Clients & so on). In the patch submitted for HDFS-1974, Namenode (NamenodeRpcServer) implements the HAServiceProtocol interface & provides the implementation based on Shared Storage approach. Now when I want to provide another implementation based on Backup Node, I am confused how fit it into the HA framework. This is the point I want to make.
                
> Generalize the HAServiceProtocol interface
> ------------------------------------------
>
>                 Key: HDFS-2354
>                 URL: https://issues.apache.org/jira/browse/HDFS-2354
>             Project: Hadoop HDFS
>          Issue Type: Sub-task
>          Components: name-node
>            Reporter: Justin Joseph
>            Assignee: Justin Joseph
>         Attachments: HAService_fw_Class_Diagram.JPG, HDFS-2354.1.patch, HDFS-2354.patch, Namenode HA using Backup Namenode as Hot Standby.pdf
>
>
> This JIRA intends to revisit the patches committed for HADOOP-7455 and HDFS-1974 & to provide more generic interfaces which allows alternative HA implementations to co-exist complying with HAServiceProtocol.
> Some of the considerations are
> 1) Support life cycle methods (start*() and stop() APIs) in HAServiceProtocol
> 2) Support custom states in HAServiceProtocol
> 3) As per the patch submitted for HDFS-1974, Namenode implements HAService interface. This needs to be reconsidered.
> I will elaborate on these points, in the form of comments below.

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