A distributed execution engine for cloud computing
CIEL is a distributed execution engine for task- and data-parallel
computation. It masks the complexity of distributed programming by
providing distributed storage, transparent inter-machine communciation
and transparent fault tolerance.
A CIEL job comprises one or more “tasks”, each of which is associated
with an “executor”. This package includes several generic executors
for integrating with UNIX utilities or programs that implement the
CIEL executor interface. In addition, the following executors can be
downloaded and installed separately:
Skywriting is a scripting
language for use with CIEL. It provides a “distributed thread”
abstraction that enables you to write simple scripts that spawn
tasks using any executor, and use control-flow features such as
loops and conditionals.
Java support is provided by
writing classes that implement a Task
Java interface. There is
also experimental support for using Scala to write distributed
threads.
OCaml support is provided by
using delimited continuations to serialise OCaml into CIEL tasks.
Before installing CIEL, you will need to install all of its
dependencies:
Before running CIEL, you may need to install various dependencies. We
develop CIEL on Ubuntu 10.04 and Fedora, and use the following packages;
however, these may vary based on the exact version of your operating
system.
±-----------------------------------------------------±--------------------±--------------------+
Packages | apt-get |
yum install |
---|---|---|
Python 2.5+ | python |
python |
httplib2 | python-httplib2 |
python-httplib2 |
simplejson | python-simplejson |
python-simplejson |
CherryPY 3.1.2+ | python-cherrypy3 |
python-cherrypy3 |
PycURL | python-pycurl |
python-pycurl |
cURL | curl |
curl |
lighttpd | lighttpd |
lighttpd |
flup | python-flup |
python-flup |
±-----------------------------------------------------±--------------------±--------------------+ |
To install CIEL, use the setup.py
script. For example, you may type
the following commands in the current directory:
$ python setup.py build
$ sudo python setup.py install
A CIEL cluster contains one “master” process and one or more “worker”
processes.
To start a master, use the following command:
$ ciel master
To start a worker on the same machine, use the following command:
$ ciel worker
To start a worker on a different machine, use the following command:
$ ciel worker -m http://${MASTER_HOSTNAME}:8000/
To find out about more options when running a master and workers, use
the following command:
$ ciel [master|worker] --help
To run a simple CIEL job, first create a file called test.pack
with
the following contents:
{"start":
{"handler": "stdinout",
"args":
{"args":
{"command_line": ["echo", "Hello, world!"]}
}
},
"result": [{"__decode_ref__": "noop"}]
}
This is a simple example of a “package file”, which is used to specify
a CIEL job. Package files are the most flexible way of specifying a
CIEL job, but some executors (such as Skywriting) provide simpler ways
to create simple jobs.
To execute the package file, first start a cluster, then type the
following command:
$ ciel run test.pack