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https://issues.apache.org/jira/browse/HADOOP-5363?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12689222#action_12689222
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Chris Douglas commented on HADOOP-5363:
---------------------------------------
For the forwarding servlets, I was thinking that a single servlet could handle
the requests for anything but "/file", which gets handled by a different
servlet registered for those requests. The servlet handling "/file" can be a
subclass of the normal forwarding servlet, overriding a function that contains
the "else" clause in the base class, and the behavior for "/file" in the
subclass servlet. So in ProxyForwardServlet, there's a call out of
{{forwardRequest}} to some function {{buildForwardPath}} (or whatever), that in
ProxyForwardServlet contains the equivalent to the "else":
{noformat}
+ if (request.getPathInfo() != null) {
+ path += request.getPathInfo();
+ }
+ if (request.getQueryString() != null) {
+ path += "?" + request.getQueryString();
+ }
{noformat}
but in the subclass registered for "/file" requests, {{buildForwardPath}}
contains the equivalent to:
{noformat}
+ // use streamFile for file access
+ path = "/streamFile";
+ path += "?filename=" + request.getPathInfo();
+ UnixUserGroupInformation ugi =
(UnixUserGroupInformation)request.getAttribute("authorized.ugi");
+ if (ugi != null) {
+ path += "&ugi=" + ugi.toString();
+ }
{noformat}
So then the behavior is bound to the servlets registered to these paths, rather
than making the behavior of this servlet vary depending on the paths to which
it is bound.
> Proxying for multiple HDFS clusters of different versions
> ---------------------------------------------------------
>
> Key: HADOOP-5363
> URL: https://issues.apache.org/jira/browse/HADOOP-5363
> Project: Hadoop Core
> Issue Type: New Feature
> Components: contrib/hdfsproxy
> Reporter: Kan Zhang
> Assignee: zhiyong zhang
> Attachments: HADOOP-5363.patch, HADOOP-5363.patch, HADOOP-5363.patch
>
>
> A single hdfsproxy server should be able to proxy for multiple HDFS clusters,
> whose Hadoop versions may be different from each other.
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