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environment, separation from the portlet
implementation programming language,
velocity engine template support for
content display and integration with other
Open Source applications have already
been solved.
The GSN has developed further the Open Source
portal to support LDAP authentication over secure
password encryption (encrypted with the Unix
Encryption algorithm according to the SUN ONE
LDAP Server), to support personalized pages for
every registered user and to make the login
procedure easier by keeping the navigation of an
anonymous user when he/she decides to login to the
portal. Furthermore, the appropriate modules have
been created so that all the available portlets of the
Jetspeed portal can support LDAP authentication. A
single sign-on system has been implemented which
allows all GSN members to use all services
requiring login after they have logged-in once in the
GSN web portal. The web portal has more than
50.000 users who have their own customized views
of the web portal.
To support a higher number of concurrent users
we have implemented a load balancing technique.
The Apache httpd server (Apache Server Project,
1996) is the main web server in use, combined with
at least one application server, which offers the
execution environment for Servlets and JSP pages.
The Apache web server handles all incoming
requests, forwarding them to the application servers
using the mod_jk module. Each application server
hosts an identical version of the Web Portal.
3.2 E-mail and E-mail Lists
This service is used by the Greek educational
community and by the Vocational Training
personnel. The accounts for the service are separated
in the following user groups: a) Accounts for
Schools and Administrative units, b) Accounts for
Teachers, c) Accounts for Students.
The service has all the standard characteristics of
an e-mail service, plus some additional
characteristics we have developed in order to
provide a more flexible and secure service to the
educational community. The extra features provided
include, virus protection using the Sophos antivirus
software that is installed in all GSN mail servers and
spam protection with new anti-spamming filters.
Spam protection is activated only upon user
request (through a corresponding checkbox in the
web portal), and when it is activated a new folder,
named “spam”, appears in the users mailbox. When
a message is tagged as “spam” (in the GSN mail
server, when the message has been sent more than a
predefined number of times and the sender does not
have the right to send multiple messages), it is
automatically placed in the spam folder. The user
may also choose to categorize as spam all the e-
mails arriving from known spam sources that are in
GSN's rbl lists.
The mailing list service enables the development
and maintenance of mailing lists that can be used to
deliver a large number of messages to large numbers
of GSN users. There are two main categories of
mailing lists currently active in GSN: lists with
dynamic subscription of members, and lists with
static subscription of members. In the lists that allow
dynamic subscription, the members are coming from
the LDAP directory Server of the GSN. The list mail
address may, for example, look like dim@sch.gr,
where the above list may identify all the first grade
schools of Greece. In the lists with static
subscription, the list administrator can enlist one or
more users, or the users themselves can become
members of the lists of their choice, by filling in
their e-mail and some personal data in the
appropriate web form.
To prevent the members of the lists from
accessing material that is inconsistent with the GSN
terms of use, most of the lists have a moderator who
is responsible for the material that is distributed
through the lists. Some lists are completely open, but
these are a minority. The use of a moderator is
mandatory in most cases, because the educational
community is a very special community of people
and messages that contain spam, viruses,
pornography and other related content must not be
allowed in the users’ mailboxes.
3.3 News Service, Forum
Discussions and Electronic
Magazine
The news service allows registered users, such as
schools and teachers, to post announcements. The
announcements are hierarchically grouped, based on
their content to different categories and topics. Each
announcement has a certain scope: it may apply to
the users of a specific educational unit, a prefecture,
the group of all registered units, etc. The GSN portal
also offers to its members a forum discussion board
which allows the users to create new posts, reply to
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