[okfn-discuss] What Do We Mean by Componentization (for Knowledge)?
Rufus Pollock
rufus.pollock at okfn.org
Tue May 1 11:53:33 UTC 2007
Also at:
<http://blog.okfn.org/2007/04/30/what-do-we-mean-by-componentization-for-knowledge/>
~rufus
## Background
Nearly a year ago I wrote a short essay entitled [The Four Principles of
(Open) Knowledge
Development](http://blog.okfn.org/2006/05/09/the-four-principles-of-open-knowledge-development/)
in which I proposed that the four key features features of a successful
(open) knowledge development process were that it was:
1. Incremental
2. Decentralized
3. Collaborative
4. Componentized
As I emphasized at the time the most important feature -- and currently
least advanced -- was the last: Componentization. Since then I've had
the chance to discuss issue further, most recently and extensively at
[Open Knowledge 1.0](http://www.okfn.org/okcon/) and this has prompted
me to re-evaluate and extend the ideas I put forward in the original essay.
## What Do We Mean By Componentization?
> Componentization is the process of **atomizing** (breaking down)
resources into separate reusable **packages** that can be easily recombined.
Componentization is the most important feature of (open) knowledge
development as well as the one which is, at present, least advanced. If
you look at the way software has evolved it now highly componentized
into packages/libraries. Doing this allows one to 'divide and conquer'
the organizational and conceptual problems of highly complex systems.
Even more importantly it allows for greatly increased levels of reuse.
The power and significance of componentization really comes home to one
when using a package manager (e.g. apt-get for debian) on a modern
operating system. A request to install a single given package can result
in the automatic discovery and installation of all packages on which
that one depends. The result may be a list of tens -- or even hundreds
-- of packages in a graphic demonstration of the way in which computer
programs have been broken down into interdependent components.
## Atomization
Atomization denotes the breaking down of a resource such as a piece of
software or collection of data into smaller parts (though the word
atomic connotes irreducibility it is never clear what the exact
irreducible, or optimal, size for a given part is). For example a given
software application may be divided up into several components or
libraries. Atomization can happen on many levels.
At a very low level when writing software we break thinks down into
functions and classes, into different files (modules) and even group
together different files. Similarly when creating a dataset in a
database we divide things into columns, tables, and groups of
inter-related tables.
But such divisions are only visible to the members of that specific
project. Anyone else has to get the entire application or entire
database to use one particular part of it. Furthermore anyone working on
any given part of one of the application or database needs to be aware
of, and interact with, anyone else working on it -- decentralization is
impossible or extremely limited.
Thus, atomization at such a low level is not what we are really
concerned with, instead it is with atomization into **Packages**:
## Packaging
By packaging we mean the process by which a resource is made reusable by
the addition of an external interface. The package is therefore the
logical unit of distribution and reuse and it is only with packaging
that the full power of atomization's "divide and conquer" comes into
play -- without it there is still tight coupling between different parts
of a given set of resources.
Developing packages is a non-trivial exercise precisely because
developing good *stable* interfaces (usually in the form of a code or
knowledge API) is hard. One way to manage this need to provide stability
but still remain flexible in terms of future development is to employ
versioning. By versioning the package and providing 'releases' those who
reuse the packaged resource can use a specific (and stable) release
while development and changes are made in the 'trunk' and become
available in later releases. This practice of versioning and releasing
is already ubiquitous in software development -- so ubiquitous it is
practically taken for granted -- but is almost unknown in the area of
knowledge.
## A Basic Example: A Photo Collection
Imagine we had a large store of photos, say more than 100k of individual
pictures (~50GB of data at 500k per picture). Suppose that initially
this data is just sitting as a large set of files on disk somewhere.
Consider several possibilities for how we could make them available:
1. Bundle all the photos together (zip/tgz) and post them for download.
Comment: this is a very crude approach to componentization. There is
little atomization and the 'knowledge-API' is practically non-existent
(it consists solely of the filenames and directory structure).
2. In addition tag or categorize the photos and make this database
available as part of the download. Comment: By adding some structured
metadata we have started to develop an 'knowledge-API' for the
underlying resource that makes it more useful. One could now write a
screensaver program which showed photos from a particular category or
auto-import photos by their area.
3. In addition suppose the photos fall into several well-defined and
distinct classes (e.g. photos of animals, of buildings and of works of
art). Divide the photo collection into these three categories and make
each of them as a separate download. Comment: A initial step on
atomizing the resource to make it more useful, after all 5GB is rather a
lot to download for one photo.
4. In addition to dividing them up allow different people to maintain
the tags for different categories (one might imagine those knowledgeable
about animals are different from those knowledgeable about art).
Comment: Atomization assists the development of good knowledge-APIs (the
human mind is limited and divide and conquer helps us deal with the
complexity).
5. Standardize the ids for each photo (if this hasn't been done already)
and separate the tags/categories data from the underlying photo data.
This way multiple (independent) groups can provide tags/categorization
data for the photos. Comment: Repackaging -- along with the development
of a better knowledge-API for the basic resource -- allows a dramatic
decrease in the level of coupling and increase the scope for independent
development of complementary libraries (the tags). This in turn will
increase the utility to end users.
## Conclusion
In the early days of software there was also little arms-length reuse
because there was little packaging. Hardware was so expensive, and so
limited, that it made sense for all software to be bespoke and little
effort to be put into building libraries or packages. Only gradually did
the modern complex, though still crude, system develop.
The same evolution can be expected for knowledge. At present knowledge
development displays very little componentization but as the underlying
pool of raw, 'unpackaged', information continues to increase there will
be increasing emphasis on componentization and reuse it supports. (One
can conceptualize this as a question of interface vs. the content.
Currently 90% of effort goes into the content and 10% goes into the
interface. With components this will change to 90% on the interface 10%
on the content).
The change to a componentized architecture will be complex but, once
achieved, will revolutionize the production and development of open
knowledge.
--
Executive Director, Open Knowledge Foundation
m: +44 (0)7795 176 976
www: http://www.okfn.org/ | blog: http://blog.okfn.org/
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