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https://issues.apache.org/jira/browse/ATLAS-571?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15214232#comment-15214232
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Hemanth Yamijala commented on ATLAS-571:
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Change impact:
* When {{AtlasClient}} is started in HA mode, it needs to find the active
instance. This can be done by querying Zookeeper or by enhancing the admin
status API of ATLAS-513 to return the current active server address.
* During course of operation of a client, an Active instance could be brought
down. This will cause a Jersey {{ClientHandlerException}}. If this occurs, the
client can detect the new active instance again from Zookeeper.
* The same can be done if the client gets a response with status code
SERVICE_UNAVAILABLE (which can happen during transitionary states).
* I tested GETs and POSTs using {{AtlasClient}} APIs pointed to a passive
instance. These are automatically redirected to the active, and the Jersey
client is automatically handling them. This is as per the default value for
following redirects as documented here:
https://jersey.java.net/apidocs/1.19/jersey/com/sun/jersey/api/client/config/ClientConfig.html#PROPERTY_FOLLOW_REDIRECTS.
This does mean that an AtlasClient created pointing to a passive instance will
continue to query the passive (and get automatically redirected) until one of
the errors mentioned above occurs. In Jersey 2.x, there seems to be ways of
detected the redirected location (JERSEY-1611). However, we could probably take
this enhancement later.
I will continue implementation on these lines. Please let me know if anyone has
comments.
> Modify Atlas client for necessary changes in context of HA
> ----------------------------------------------------------
>
> Key: ATLAS-571
> URL: https://issues.apache.org/jira/browse/ATLAS-571
> Project: Atlas
> Issue Type: Sub-task
> Reporter: Hemanth Yamijala
> Assignee: Hemanth Yamijala
>
> In ATLAS-511, we are introducing mechanisms to handle automated failover and
> also redirecting of requests etc. This JIRA is to test and make necessary
> changes to the AtlasClient class to take advantage of these changes and
> behave in an optimal manner. This implementation could also serve as a model
> for others who are writing their own clients against the Atlas API.
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