Motivation • Features • Installation • Basic Usage • Documentation

LCLS endstations deal with dynamic sets of instrumentation. Information like ports, triggers and aliases are all important for operation, but hard to manage when spread across a multitude of applications. Happi solves this problem by creating a single access point for all the metadata required to interface with LCLS instrumentation. Using a flexible container based system Happi allows the enforcement of specific conventions while still permitting flexible data entry where required.

• Manage information for specific device types using containers
• Input arbitrary metadata associated with a specific device
• Flexible backend support for multiple types of databases; MongoDB, JSON e.t.c
• Easily search database entries for device/s that match a set of keys

Install the most recent tagged build: conda install happi -c pcds-tag -c conda-forge

Install the most recent development build: conda install happi -c pcds-dev -c conda-forge

The happi.Client is your main interface to the underlying device database. You have the choice of either creating your database backend by hand or using the environment variable $HAPPI_BACKEND to create a persistent reference to your database type. By default, the Client assumes a JSON file database:

   import happi

   client = happi.Client(path='path/to/my_db.json')

If your database has entries, you should either be able to search by key variables for individual or multiple devices.

   client.find_device(name="My Device")

   client.search(stand='DG2')

Once you have the device you want, you can edit the information just as you would any other Python object. View the device information in a convenient table using .show_info:

   dev = client.find_device(name="My Device")

   dev.z = 432.1

   dev.show_info()

+--------------+----------------------+
| EntryInfo    | Value                |
+--------------+----------------------+
| active       | True                 |
| beamline     | LCLS                 |
| name         | My Device            |
| parent       | None                 |
| prefix       | MY:DEV:01            |
| stand        | None                 |
| system       | None                 |
| z            | 432.10000            |
+--------------+----------------------+

After you are satisfied with your changes, push the information back to the database using the .save method. If this is a new device, you will have to call Client.add_device. Before the entry is modified in the database, the happi.Client confirms that the new changes meet all the requirements specified by the container.

   dev.save()