Getting Started
Accessing Data

Getting Started: Accessing Data

The developers of the Pelican Platform believe data is the lifeblood of science. That's why Pelican provides a suite of tools that make it easy for researchers to federate their data, giving them the ability to share objects from a broad range of data repositories and allowing them to connect their data with distributed computational capacity, such as the OSPool. For more information on Pelican, visit the About Pelican page.

Before Starting

Assumptions

Before using the Pelican client to interact with objects, this guide makes several assumptions:

  • You are on a computer where you have access to a terminal. The Pelican client is a command line tool.

  • You've already installed the version of Pelican appropriate for your system, and Pelican is accessible via your path. To test this on Linux, you can run

    which pelican

    which should output a path to the executable. If there is no output to this command, refer to the Pelican installation docs to acquire a working installation.

Useful Terminology

To learn our terminology and about Pelican's architecture, we recommend you read through the About Pelican page and Core Concepts and Terminology page to learn how Pelican works and how it can be useful to you.

Your First Pelican Client Command

You can easily access public objects from a Pelican federation with the use of the Pelican client commands. Here we will be using the pelican object get command to get an object from a federation. This command is formatted like so:

pelican object get pelican://<federation-url>/<object-path> </local/path/to/destination>

We can break down the components of this command before you try it yourself:

  • pelican object get: This is the client command we are utilizing. object because we want to interact with Pelican objects and get because we want to GET the file from our federation.
  • pelican://: This is the URL scheme for accessing this object. Pelican accepts different URL schemes which are detailed in the Pelican Client usage page.
  • <federation-url>: The URL indicating which federation you would like to interact with.
  • <object-path>: The path to the object we would like to get.
  • </local/path/to/destination>: The local destination where we want the file to download to (can be a local or absolute path)

Try The Command Yourself

Now it is time for you to get your first object from a federation. Before getting your first object, be sure you are in a directory/location where you want to download this test file. To get the object, run the command below:

pelican object get pelican://osg-htc.org/ospool/uc-shared/public/OSG-Staff/validation/test.txt downloaded-test.txt

Note: with pelican:// URLs like the one above, it is important to include the correct number of slashes (/). This is because pelican URLs rely on the hostname being the federation URL therefore, they must only contain two slashes after pelican. For more information, visit the Pelican Client Usage page

You should see a progress bar output and eventually a file named downloaded-test.txt within your local directory:

$ pelican object get pelican://osg-htc.org/ospool/uc-shared/public/OSG-Staff/validation/test.txt downloaded-test.txt
downloaded-test.txt 14.00 b / 14.00 b [==============================================================================] Done!
$ ls
downloaded-test.txt
$ cat downloaded-test.txt
Hello, World!

Where to Go from Here

For More Info on Pelican:

For Users:

For Admins:

ConfigurationPelican Client