Description
We can also do a Streaming job to allow other languages to use Hama's BSP API.
Basically you fork a new process in the BSP method, then set a inputstream for the process which it can read very simple.
Then an outputstream from the childprocess can be read to give it following abilities:
- get a received message
- send a new message
- sync
- read a line from input
- write to output
- reset the input to reread
Those actions must have a constant prefix, for example send a message could look like this:
%SEND_MESSAGE%=this is the message
or sync:
$SYNC$=
The logic behind it is that we can simply split in Java code by "=" and the lefthand side is the action and the righthandside is the value of this action.
Between the peers the messages are Text, which has some overhead but is easier to implement and the communication between the BSP task and the forked process is based on text/strings anyway.
This time I do not advise to copy the whole streaming from Hadoop itself. However the parts that repacks the jar with needed execution scripts and the option handling seems good to reuse.
The input- and outputstream handling must be written from scratch because we want to take actions into account.
Attachments
Attachments
Issue Links
- relates to
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HAMA-619 Hama Pipes
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- Resolved
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