Albatross is a small toolkit for developing highly stateful web applications.
The toolkit has been designed to take a lot of the pain out of constructing intranet applications although you can also use Albatross for deploying publicly accessed web applications.
In slightly more than 4500 lines of Python (according to pycount) you get the following:
An extensible HTML templating system similar to DTML including tags for:
Application classes which offer the following features:
The ability to deploy applications as CGI, FastCGI, mod_python or a pure python HTTP server by changing less than 10 lines of code.
The toolkit application functionality is defined by a collection of fine grained mixin classes. Nine different application types and six different execution contexts are prepackaged, you are able to define your own drop in replacements for any of the mixins to alter any aspect of the toolkit semantics.
Application deployment is controlled by your choice of either cgi, FastCGI, mod_python, or BaseHTTPServer Request class. It should be possible to develop a Request class for Medusa or Twisted to allow applications to be deployed on those platforms with minimal changes.
Albatross comes with over 170 pages of documentation. HTML, PDF and PostScript formatted documentation is available from the toolkit homepage.
The toolkit homepage:
The Albatross mailing list subscription and archives:
CHANGES SINCE 1.20
Any HTML tag can now be prefixed with "al-" allowing any attribute to be the result of python evaluation. For example:
<al-td colspanexpr="i.span()"> could produce <td colspan="3">
<al-input name="abc.value" disabledbool="abc.isdisabled()"> could produce <input name="abc.value" disabled>
Since macros and lookups are an application global resource, they can only be defined once per application, however this was not previously checked. Redefinition of macros or lookups will now result in an ApplicationError exception.
an in-line version of the <al-lookup> tag has been introduced, which is expanded in place if the tag has an expr= attribute.
a new <al-require> tag has been added to allow templates to assert that specific Albatross features are available, or templating scheme version number is high enough.
"Cache-Control: no-cache" is now set in addition to "Pragma: no-cache"
Simplified session cookie handling.
BUGFIXES SINCE 1.20:
FastCGI apps were not being explicitly finalised, relying instead on their object destructor, with the result that writing application output (or errors) would be indefinitely deferred if object cycles existed. We now call "fcgi.Finish()" from the fcgiapp Request.return_code() method.
When handling exceptions, the traceback is now explicitly deleted from the local namespace to prevent cycles (otherwise the garbage collection of other objects in the local namespace will be delayed).
Two fixes to the <al-select> tag: the albatross-specific "list" attribute was leaking into resulting markup, and the use of the "expr" attribute would result in invalid markup being emitted.
Thanks to Robert Fendt for picking this up: the Albatross-generated hidden field input element must not appear naked inside a form element for strict HTML conformance. The solution is to wrap the input elements in div.
BranchingSession sessions could not be "deleted" - the solution is to add a dummy "session" shared by all branches, which is deleted when one branch "logs out".
-- Andrew McNamara, Senior Developer, Object Craft http://www.object-craft.com.au/