Zope is like that to me. I ask what is it and the answer
sounds like "Oh, it's oierbv for the zxcvioupo of 7cvn^djh'.
Now understand, I know what very well what Python, Apache, PhP,
MySQL, IE and javascript do. I just don't know what Zope
does.
You know, that's a good question. Let's see if I can make a good
answer:
Zope is the "Z Object Publishing Environment".
It publishes a *tree* of *objects* stored in the ZODB which is
an object oriented database. Think of it as a monstrous pickle
implementation.
Zope folders are a lot like user-defined classes in your application.
They contain things, which is why they're called "folders". But
basically, from a programming perspective, what they contain
are their "attributes" in the class/object jargon (in reality it can
be more complicated, some containers use Python container
types like dictionary or list as their internal structure).
Of course, "publishes" means "publishes to the web".
Z:
So Zope includes an *object store*, a *publisher*,
and a *web server*. When the web server receives a request,
it asks the publisher to get it, which digs it out of the object
store. Then it goes back the other way, back to the requester
via the web.
Usually, you run the Zope webserver behind another proxy
like Apache, but it is possible to serve a site directly from
Zope. I never do that for production, because, Apache, being
much more completely tested is a safer bet for not crashing
or misbehaving under heavy loads. However, the built-in
Zope webserver (I believe it was once called Medusa) is
quite convenient for development and testing.
OBJECT:
Because Zope publishes Python *objects* instead of *files*,
they can have much richer structure (e.g. metadata) than
a site based on files stored in a filesystem. However, a set
of files stored in a filesystem is very much like an object
database, so
1) The ZODB is sometimes called the Zope Object FileSystem,
which I find a useful idea --- especially since ZOFS has some
extra constraints beyond what ZODB requires.
2) You actually can store contents of the ZODB *as* a filesystem
with associated metadata in auxiliary files. I believe this is
how the "filesystem storage" option for ZODB works (by default,
ZODB lumps all its data into one big container file "Data.fs" --
this is the "filestorage" option).
PUBLISHING:
Zope has also been called a "web application server", because
it's relatively easy to write highly-integrated, highly-dynamic
sites with it (and overkill to use it for purely static sites).
Objects are defined in such a way that they can be represented
as web pages. The publisher has a lot of default behaviors for
built-in types and the objects that come with Zope.
Zope "product" developers have the responsibility (and control)
over how their objects will appear when published.
ENVIRONMENT:
If you want to think of it as a "web application server", then
basically, Zope is your "operating system", and your site is
your "web application software".
Zope also provides some specialized programming language
help --- Python scripts that can be edited through the web,
and two "Templating Languages" for designing web pages that
will have dynamic content. You can think of the templating
languages as being similar to PHP or ASP style programming.
But "Zope Zen" says that the serious code should be either
in Python scripts or in Python products (on the filesystem,
instead of in the ZODB, like scripts). Templates are meant
to be simple, simple, simple. But that's a style issue.
This stuff provides the Zope "operating system" with a
"shell". And the "Zope Management Interface", which is
what you see when you visit the /manage page at a Zope
site, is the "window system" or, perhaps more accurately,
the "file browser" of that "operating system".
So, in fact, Zope does quite a bit. But it isn't really all
that hard to understand. It's just not been well-introduced,
because the people explaining it have a tendency to forget
that it isn't all obvious, because it seems that way to
them, now that they know it.
But that's the newbie's problem in all areas of software, ISTM.
HTH,
Terry
