Connecting to ServiceX¶

You need a ServiceX endpoint where transformation is happening and a client library to submit a transformation request.

Selecting an ServiceX endpoint¶

ServiceX is a hosted service. Each ServiceX instance is deployed at the server and dedicated to a specific experiment. Depending on which experiment you work in, there are different instances you can connect to. Some can be connected to from the outside world, while others are accessible only from a Jupyter notebook running inside the analysis facility.

Collaboration	Name	URL
ATLAS	Chicago Analysis Facility	https://servicex.af.uchicago.edu/
CMS	Coffea-Casa Nebraska	https://coffea.casa/hub
CMS	FNAL Elastic Analysis Facility	https://servicex.apps.okddev.fnal.gov

For ServiceX endpoints that can be connected from the outside, e.g. ATLAS Chicago Analysis Facility, you need to follow steps below to download a ServiceX access file.

Click on the Sign-in button in the upper right hand corner. You will be asked to authenticate via GlobusAuth and complete a registration form. Once this form is submitted, it will be reviewed by SSL staff. You will receive an email upon approval.

At this time you may return to the ServiceX page. Click on your name in the upper right hand corner and then select Profile tab. Click on the download button to have a servicex.yaml file generated with your access token and downloaded to your computer.

ServiceX Access File¶

The client relies on a servicex.yaml file to obtain the URLs of different servicex deployments, as well as tokens to authenticate with the service.

The client library will search for this file in the current working directory and then start looking in parent directories and your home directory until a file is found.

The format of this file is as follows:

api_endpoints:
  - endpoint: https://servicex.af.uchicago.edu
    name: servicex-uc-af
    token: <YOUR TOKEN>

cache_path: /tmp/ServiceX_Client/cache-dir
shortened_downloaded_filename: true

cache_path and shortened_downloaded_filename are optional fields and default to reasonable values.

The cache database and downloaded files will be stored in the directory specified by cache_path.

The shortened_downloaded_filename property controls whether downloaded files will have their names shortened for convenience. Setting to false preserves the full filename from the dataset.

ServiceX Client Installation¶

ServiceX client Python package is a python library for users to communicate with ServiceX backend (or server) to make transformation requests and handling of outputs.

Prerequisites¶

Python 3.8, or above
Access to ServiceX endpoint

Installation¶

pip install servicex

You’re all set to make your ServiceX transformation request!