THIS IS A TEST INSTANCE. ALL YOUR CHANGES WILL BE LOST!!!!
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| # | Class name | Description |
|---|---|---|
| 1 | HaUrlRewriteFunctionDescriptor | Describes function that resolves URLs in HA mode |
| 2 | HaUrlRewriteFunctionProcessor | Implements main logic of defining active or standby URL |
| 3 | HaBaseStrategyHostMapper | Implements base strategy for HA mode. Contains parameters: retryCount, timeoutInterval. |
Provider configuration example
Enables or disables HA Provider and binds strategy and provider together. Alias contains list of Hadoop services (name-nodes in our case: active and standby) grouped into one entity.
| Code Block | ||||||
|---|---|---|---|---|---|---|
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<topology>
<gateway>
...
<provider>
<role>ha</role>
<name>HAProvider</name>
<param>
<name>webhdfs.ha</name>
<value>failover_strategy=BaseStrategy;retryCount=3;timeoutInterval=5000;enabled=true</value>
</param>
</provider>
...
<gateway>
...
<service>
<role>WEBHDFS</role>
<url>machine1.example.com:50070</url>
<url>machine2.example.com:50070</url>
</service>
...
<service>
<role>NAMENODE</role>
<url>machine1.example.com:50070</url>
<url>machine2.example.com:50070</url>
</service>
...
</topology> |
- failover_strategy – indicates how to define active service and contains some configuration parameters. Default value is BaseStrategy. BaseStrategy for failover has following parameters:
- retryCount – indicates how many times knox will ping name-node before knox decides that namenode is down.
- timeoutInterval – interval for connection timeout.
- enabled – indicates whether HAProvider is active or not for service.
Example UML
| PlantUML | ||||
|---|---|---|---|---|
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autonumber
participant "Deployment\nFactory\n(df)" as df |
Example Code Block
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| language | java |
|---|---|
| title | Code Title |
| linenumbers | true |
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See Pic.#2 for UML sequence diagram for UrlRewriteProcessor.
Pic #3 – UML sequence diagram for UrlRewriteProcessor.
Provider configuration example
Please look at the WebHDFS HA section http://knox.apache.org/books/knox-0-5-0/knox-0-5-0.html#WebHDFS