Usage in ROOT

We have also created a davix plugin for ROOT, TDavixFile. It can be used to perform I/O on HTTP, WebDAV or S3.

Installation from EPEL repositories

Install root and root-davix
```
$ sudo yum install root root-net-davix
```

Enable the davix plugin by default

$ sudo sed -i 's/Davix.UseOldClient: yes/Davix.UseOldClient: no/g' /usr/share/root/system.rootrc

Tune configuration of rootrc with your HTTP parameters. See the available options in Configure TDavixFile.
```
$ vim /usr/share/root/system.rootrc
```

Installation from source

Download your favorite version of ROOT from https://root.cern.ch
Install the dependencies: cmake, openssl-devel, libxml2-devel
Run installDavix.sh which downloads and compiles davix.
Configure ROOT with --with-davix-incdir and --with-davix-libdir indicating the davix installation created by installDavix.sh. Davix should be displayed in the list of “enabled modules” at the end of the configuration step.
Compile ROOT.

Usage

Using Davix is completely transparent once installed and configured, just proceed like with any other TFile plugin.

TFile* f  = TFile::Open("http://root.cern.ch/files/h1big.root")

Debugging

To use ROOT’s logging, increase the gDebug variable level.
```
$ gDebug = 2
```
To use Davix’s internal logging, use the Davix.Debug parameter. It can be used independently of gDebug. To display only Davix’s logging infomation, set gDebug to 0 and Davix.Debug to 1-4, with 4 being most verbose. In code:
```
$ gEnv->SetValue("Davix.Debug", 4);
```
In system.rootrc:
```
$ Davix.Debug: 4
```

Configure TDavixFile

TDavixFile can be configured via the system.rootrc file, via ROOT environment variables or via TFile::Open flags at runtime. All configuration parameters are documented inside system.rootrc. Main options:

Feature	ROOT parameter	Value
Enable/disable grid authentication support	Davix.GSI.GridMode	y/n
Enable/disable TLS certificate validity check	Davix.GSI.CACheck	y/n
Specify S3 authentication tokens	Davix.S3.SecretKey	string
Specify S3 authentication tokens	Davix.S3.AccessKey	string
Specify user x509 credentials in PEM format	Davix.GSI.UserCert	filepath (string)
Specify user x509 credentials in PEM format	Davix.GSI.UserKey	filepath (string)
Specify VOMS proxy to use	Davix.GSI.UserProxy	filepath (string)
Define log verbosity	Davix.Debug	integer (1-4)

Running HTTP ROOT TDavixFile Benchmarks

Check this repository: https://github.com/cern-it-sdc-id/tdavixfile-bench-tools.git