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

From: Massimiliano Fasi <Massimiliano.Fasi_at_pg.infn.it>
Date: Tue, 17 Apr 2012 17:29:28 +0200

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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