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https://issues.apache.org/jira/browse/HDFS-453?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12742874#action_12742874
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Steve Loughran commented on HDFS-453:
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* I like the tests here; nice trick of handing off to the XML parser the task
of retrieving the XML; no need for any other work on your part.
* I'm not sure that dfshealth.xml.jsp is valid XML though, as there is a </br>
at the end of <inode_limit>, which worries me
* regarding JSP vs JSPX, yes, the .jspx files are parsed differently - they
have to be well-formed XML, as defined by the JSP 2.0 specification:
http://java.sun.com/products/jsp/reference/api/index.html
JSPX pages stop you accidentallly getting too much stuff in front of the <? xml
?> page, and encourage you to create well-formed XML as for all the bits that
aren't scriptlet-generated text, your IDE will tell you off in advance, as will
the JSP compiler.
I'm attaching the .jspx equivalent, which
# moves everything to the jspx syntax
# adds a todo item where the page doesn't handle the risk that the application
isn't bonded to a namenode. Is this a risk?
# turns off cache control
I've already mentioned in HDFS-91 that JSP content doesn't expire, which will
burn anyone monitoring through a proxy server. Ideally we should have a JSP tag
library that does this for every page, so there's no need to do it by hand in
every JSP page.
> XML-based metrics as JSP servlet for NameNode
> ----------------------------------------------
>
> Key: HDFS-453
> URL: https://issues.apache.org/jira/browse/HDFS-453
> Project: Hadoop HDFS
> Issue Type: New Feature
> Reporter: Aaron Kimball
> Assignee: Aaron Kimball
> Attachments: dfshealth.xml.jspx, HDFS-453.2.patch, HDFS-453.patch
>
>
> In HADOOP-4559, a general REST API for reporting metrics was proposed but
> work seems to have stalled. In the interim, we have a simple XML translation
> of the existing NameNode status page which provides the same metrics as the
> human-readable page. This is a relatively lightweight addition to provide
> some machine-understandable metrics reporting.
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