sounds good.
On Jul 13, 2006, at 11:19 AM, Devaraj Das (JIRA) wrote:
[ http://issues.apache.org/jira/browse/HADOOP-347?
page=comments#action_12420906 ]
Devaraj Das commented on HADOOP-347:
------------------------------------
I am taking the approach where the user first connects to the
namenode's jetty and he gets redirected to a random datanode. The
random datanode (having an embedded DFS client) then gets the
directory listing (starting at the root) from the namenode (through
the regular IPC channel). The user then probably chooses a file to
view - the JSP at the backend lists the blocks of the file and he
also gets options to do HEAD, TAIL, DOWNLOAD_FULL_FILE, and,
BLOCK_VIEW (view the contents of the block in a chunked fashion
with a prev, next for navigation).
For these options he gets redirected to one of the datanodes which
has the block that he ought to view. That can be handled since the
LocatedBlock array obtained by doing dfs.namenode.open returns an
array of blocks (in the order of the bytes of the file) and the
block number & offset within that can be kept track of since the
client sends, as part of each HTTP request, the block number he
currently is at along with the offsets (start, end) that he wants
to view next. If the current datanode finishes serving up all the
chunks for the current block the client gets redirected to one of
the datanodes that has the next block with chunk offsets (0, <some-
preconfigured-value>). The current datanode knows where to send the
client to since it can also obtain the LocatedBlock array from the
namenode and figure that out from the array. The offset end (<some-
preconfigured-value>) can be customized by the user but must be a
factor of the DFS block size that the file was created with.
Implement HDFS content browsing interface
-----------------------------------------
Key: HADOOP-347
URL: http://issues.apache.org/jira/browse/HADOOP-347
Project: Hadoop
Type: New Feature
Components: dfs
Versions: 0.1.0, 0.2.0, 0.1.1, 0.3.0, 0.4.0, 0.2.1, 0.3.1, 0.3.2
Reporter: Devaraj Das
Assignee: Devaraj Das
Fix For: 0.5.0
Implement HDFS content browsing interface over HTTP. Clients would
connect to the NameNode and this would send a redirect to a random
DataNode. The DataNode, via dfs client, would proxy to namenode
for metadata browsing and to other datanodes for content. One can
also view the local blocks on any DataNode. Head, Tail will be
provided as shorthands for viewing the first block and the last
block of a file.
For full file viewing, the data displayed per HTTP request will be
a block with a PREV/NEXT link. The block size for viewing can be a
configurable parameter (the user sets it via the web browser) to
the HTTP server (e.g., 256 KB can be the default block size for
viewing files).
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