Cauldron - Abstraction layer for KTL

Cauldron is a library to remove the dependency on the Keck Telescope Library, KTL.

KTL is a system used by UC Observatories for both Lick and Keck Observatories. It is primarily a message passing system which behaves akin to a Keyword-Value store with distributed backends.

KTL uses come in two flavors: “Clients”, which read and write to a KTL service, and “Dispatchers”, which maintain the truth value of keywords for a given service.

This library provides a python drop-in replacement for both clients and dispatchers which use the KTL libraries and protocols. It is designed to seamlessly replace the need for KTL tools when running on a local, non-production machine.

• Keck Telescope Library
  • Overview
  • Clients
  • Dispatchers
  • XML
• Cauldron User’s API
  • Selecting a backend
  • Configuring the backend
  • Activate the backend
  • Cauldron-style imports
  • Using Cauldron with a test-suite
  • API Reference
• Cauldron KTL API
  • Using a Cauldron KTL Client
  • Using a Cauldron DFW dispatcher
  • API Implementation Status
  • ktl Reference/API
  • DFW Reference/API
• Configuring Cauldron
  • API Reference
• KTL XML
  • Loose KTL XML
  • Strict KTL XML
  • Locating KTL XML
• Declarative Keywords
  • Events
  • API/Reference
  • Internals
• Cauldron Backends
  • Cauldron KTL base classes
  • Local Keywords
  • ZMQ Keywords
  • Implementing a Backend
• Cauldron Internals
  • Types API Reference
  • KTL API Features
  • API Setup Functions
  • API Entry Points
  • Utilities

Installation

Cauldron is a standard python package which uses setuptools. It uses the astropy setuptools which fix some bugs and provide some nice documentation advantages. This does mean that Cauldron depends on astropy, though this is an installation and test dependency, not a runtime dependency.

Cauldron also depends on the six module. Some Cauldron backends depend on other third party modules. To install all third party modules, you can use pip:

$ pip install -r requirements.txt

To install Cauldron, use pip:

$ pip install git+https://github.com/alexrudy/Cauldron

Using Cauldron

To use Cauldron, you must first select a backend via use():

import Cauldron
Cauldron.use("local")

Then, where you would have imported a KTL library, you can call:

from Cauldron import ktl

or for the python dispatcher framework:

from Cauldron import DFW

To use the standard KTL implementation, use the “ktl” backend:

import Cauldron
Cauldron.use("ktl")

To use existing code which doesn’t follow the from Cauldron import DFW-style, you can “install” the Cauldron modules into their default place on the system.:

from Cauldron.api import install
install()

You should do this before your code imports ktl or DFW. This is a very hacky way to install a module at runtime. Then again, most of Cauldron is a giant runtime hack, so your mileage may vary.

Once you have done this, code which imports ktl or DFW will get the Cauldron versions, so the following will work:

import ktl, DFW