Hi everybody - sorry for the long posting
-:
We are a group of students taking part in a
course focused on web application
development. We've been working on/with
jetspeed for some time now, focusing
on extending the possibilities in
portlet development. We have a working
implementation of our
ideas.
We'd like to hear some feedback from you, regarding:
*
what do you think about our work?
* are there other existing
approaches to solve the same problems?
* if not, is there a chance to
integrate these things? how would the
next steps for doing so
look like?
Basically, the main tasks we adressed were
1. that
all portlets on a page share a common namespace, which may lead
to
unwanted collisions between independent portlets
2.
that portlets currently can not hold any state information
3. that
there might be portlets which take a long time to compute
their
results, but the user should get a page
immediately
4. two portlets on one page may work on the same set of
data - when that
happens, inconsistencies can occur when one
portlet updates the data from
user input while the other has
already rendered its output
* To solve problem 1., we added a parameter
called namespace into the psml
file:
<entry type="ref"
parent="NamespaceTestPortlet">
<parameter name="namespace"
value="namespace_1"/>
<layout
position="4"/>
</entry>
<entry type="ref"
parent="NamespaceTestPortlet">
<parameter name="namespace"
value="namespace_2"/>
<layout
position="5"/>
</entry>
Our Portlet then uses a function for separating its
variables into the different
namespaces (withNamespace("name") would return
"namespace_1.name" in the first
portlet, and "namespace_2.name" in the
second portlet).
* To solve problems 2 and 3, we introduced a new
concept called Worklet. Worklets
are independent objects, which are kept in
a central worklet repository. The
portlets can lookup and insert worklets
into the repository. These can be used
to preserve state information and to
let computations run in the background.
Also, different portlets may
access the same worklet, and that way share state.
We have standardized
mechanisms for expiring worklets started by users who
are no longer active.
On the other hand, we have also encapsulated the usual
"isrunning",
"isdone", "shouldbeterminated" and so on states used for long
running
worklets (MarathonWorklets).
* For the first three problems, we have
not changed the Jetspeed framework.
However to adress problem 4, we added a
new function, called update, and
processing a request works in two phases
now:
- call update on all Portlets (there is a dummy implementation for
backward
compatibility)
- call getContent on all
Portlets
That way, we can ensure that the results of the requests are
consistent when
the actual output is generated.
If anyone is interested, we can set up a
demo page on one of the university's servers here.
Cu... Stefan,
Stefan, Jens
