Hi,
We have a proposal for a persistence service (see below). Please give your
comments.
I also added the text to CVS (docs/proposals/persistence), together with
respective javadocs.
ingo.
Persistence Service Proposal
============================
GOAL: This proposal aims to establish a flexible mechanism to retrieve,
access, and store
user-specific attributes that belong to a particular portlet.
Services
--------
At the moment it is not clear to us how Jetspeed internal services can be
added to
the framework. We can think of the Persistence Service and a Location
Service (determining
the user's current location through wireless network). Others are likely
and possible.
We need a mechanism to register and retrieve these services.
Background
----------
The user PSML allows parameters to be stored with each portlet. These
parameters consist
of pairs of names and values. Today, these attributes can neither be read
nor written.
To enable portlets that render content based on user-specific customization
(eg. a POP3-portlet
requires server and account settings) these parameters have to be made
accessible to the
portlet in some way.
Persistence Service
-------------------
The idea of the Persistence Service to be minimally intrunsive to the
exisiting Portlet API.
The service has to be fed with the current RunData object and a reference
to the portlet
that uses the Persistence Service. Everything else is derived from that.
The service provides access to the pages that a portlet appears on. At the
moment, this is
just one, but in the future one can think of a user having multiple pages
(eg. one for
sport news, one for jokes, one for work), or a user having different
devices (eg. a PC browser
and a WAP phone). The Persistence Service grants access to all these pages
where the given
portlet appears on. This way, the portlet can configure itself on all these
pages at the same
time. This may not always be necessary or desirable, but there are cases
where it is, for example,
to configure a portlet for a WAP phone - given the awkward input methods
for WAP phones, the
configuration is more likely being done on the PC browser.
The service tracks all updates to the attributes on each page during the
session. Only when
the store() method is called, the attributes are persistently stored in the
respectively
PSML files. If the reset() method is called before the store() method, the
attributes are
reset to the values that are stored in the PSML file(s). If the reset()
method is called after
the store() method, the attributes are reset to values they had at the last
store(). (Very much
like commit and rollback - however, we didn't want to use these names
because they may tempt
people to think there was any kind of data integrity behind all this, which
may or may not be
the case)
Note: The configuration we are talking about here, is different from the
configuration stored
for the portlet in the portlet registration. That configuration is
the same of every
instance of the portlet, no matter what the user and page. It is
available through
the PortletConfig object and cannot be changed through the API. It
is up to the
portal administrator to change to that configuration
Pages
-----
A page is the portlet's view of its configuration data on a particular
page. It offers functions
to retrieve, add, and remove attributes to the set of attributes that
concern the portlet. An
attribute is a pair of name and value, both being of type string.
If the portlet wishes to store to store than one value for a particular
name, it can use a
vector to store all values. An attribute with only one value equals a
vector with only
one element. The elements of the vector have to be strings too.
--
--------------------------------------------------------------
Please read the FAQ! <http://java.apache.org/faq/>
To subscribe: [EMAIL PROTECTED]
To unsubscribe: [EMAIL PROTECTED]
Archives and Other: <http://marc.theaimsgroup.com/?l=jetspeed>
Problems?: [EMAIL PROTECTED]
