Openning a bunch of files placed at HTTP remote with RDataFrame

[Javier_Galan]

I tried to do the following:

ROOT::RDataFrame("AnalysisTree", "https://user:password@tweb.address.com/myData/*RawData*.root");

But I get the following problem

Error in <TDavixSystem::DavixOpendir>: failed to opendir the directory: HTTP 405 : Method Not Allowed, Permission refused  (17)

I can access normally those files one by one at the remote location using TFile::Open. Why I couldn’t do the same with RDataFrame?

[eguiraud]

Hi @Javier_Galan,

1. I guess if you pass the filenames as a list that works right? E.g.:

ROOT::RDataFrame("AnalysisTree", {"https://user:password@tweb.address.com/myData/RawData1.root, https://user:password@tweb.address.com/myData/RawData2.root"});

2. Using a glob instead (i.e. using *RawData* rather than a list), can you open those files with TChain?

Cheers,
Enrico

[Javier_Galan]

Hi Enrico,

@eguiraud

I guess if you pass the filenames as a list that works right? E.g.:

Yes, passing them as a list it works.

@eguiraud

Using a glob instead (i.e. using *RawData* rather than a list), can you open those files with TChain?

No, I cannot, I do the following (where I replaced the real address by dummy values:

root [9] TChain ch("AnalysisTree");
root [10] ch.Add("https://user:password@web.address.com/R01602*RawData*.root");
Error in <TDavixSystem::DavixOpendir>: failed to opendir the directory: HTTP 405 : Method Not Allowed, Permission refused  (17)

Thanks!
Javier

[eguiraud]

@Javier_Galan

No, I cannot, I do the following (where I replaced the real address by dummy values:

Alright, that’s the problem then, RDF is just forwarding what you pass to TChain, and TChain is not dealing with it correctly. A (not so handy, admittedly) workaround is to build the list yourself and pass the files as a list.

I don’t know whether TChain could do better and enumerate all files matching the glob even if they are hidden behind authentication, but feel free to open an issue at Issues · root-project/root · GitHub !

Cheers,
Enrico