Re: Manage a ROOT file from a streaming of the ROOT file content

Hi Fons,

> Hi Hassen,
>
> the HDFS plugin is readonly.

Thanks for the clarification!

> The idea is that you first copy the ROOT file onto HDFS and then
> access if with ROOT.

So it is possible to read directly (not through Fuse) a ROOT file stored onto HDFS. Please can you tell me the syntax? Here is for example an URI of a ROOT file in HDFS: hdfs://adminNode/user/hassen/ file.root

cheers
Hassen

>
> Cheers, Fons.
>
> On 18/04/2012 09:44, Hassen Riahi wrote:
>> Hi,
>>
>>> Hi,
>>>
>>> Another alternative is to try using the HDFS i/o plugin.
>>
>> Is there HDFS i/o plugin in ROOT? with which it is possible to write
>> directly (not through Fuse) from ROOT to HDFS.
>> If it is the case please point us to the documentation.
>>
>> cheers
>> Hassen
>>
>>>
>>> Cheers,
>>> Philippe.
>>>
>>> On 4/17/12 10:29 AM, Massimiliano Fasi wrote:
>>>> Hi all,
>>>>
>>>> In order to use Apache Hadoop with MapReduce streaming, we need a
>>>> c++
>>>> way to copy or cast a ROOT file passed through the standard input
>>>> to any
>>>> type of ROOT object (a TFile hopefully).
>>>>
>>>> Practically, we want to execute a command like
>>>>
>>>>> cat Myfile.root | MyAnalysisCode
>>>>
>>>> or
>>>>
>>>>> MyAnalysisCode < Myfile.root
>>>>
>>>> and then cast in MyAnalysisCode the standard input to something
>>>> manageable by ROOT.
>>>>
>>>> Solutions we have tried so far didn't work. In particular, we
>>>> tried to
>>>> use the ifstream library but we wasn't able to cast their objects
>>>> to
>>>> something manageable by ROOT.
>>>>
>>>> Any hints or suggestions would be very appreciated.
>>>>
>>>> Thanks,
>>>>
>>>> Massimiliano
>>>>
>>>> ----------------------------------------------------------------
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>>>> Messaging
>>>> Program.
>>>>
>>>>
>>
>
> --
> Org: CERN, European Laboratory for Particle Physics.
> Mail: 1211 Geneve 23, Switzerland
> E-Mail: Fons.Rademakers_at_cern.ch Phone: +41 22 7679248
> WWW: http://fons.rademakers.org Fax: +41 22 7669640
>
Received on Wed Apr 18 2012 - 10:25:20 CEST