Naming and directory services are traditionally supported by network servers
and are provided to users as part of their network and service provider
However, on-line connections and services evolve to become more personalized
to users and available at anytime from anywhere. The concept of Personal
Naming and Directory Service (PNDS) was developed to provide mobile
users with the part of naming and directory service that may be private
and personalized. PNDS is implemented on a smartcard and is fully integrated
in the overall naming and directory architecture through referrals (
PNDS is a generic component which is able to store a hierarchical directory
of bound objects along with pairs of attribute-value. Therefore, PNDS is
perfectly suited to store various kind of users' or network related data,
such as for example :
object references (e.g., network addresses) which allow the system and
network to bind to remote services,
user service profile entries, which personalize services the user
has subscribed to,
Users' personal applications such as for example a personal address book.
3.1 Three Modes of Operation
The PNDS leverages the LDAP concept of referrals by handling three modes
An example of using such a feature is when the user wishes to access a
specific service. As the required service information may already be stored
on the smartcard (service profile), the first lookup to the PNDS can be
performed using the Referral Ignore mode. Depending on the result,
a second attempt will be issued using Referral Throw or Referral
Follow modes, to link to the network and retrieve service profile information
from the referred server.
When set in the Referral Ignore mode, PNDS ignores every referral,
and directory lookups are perfomed locally in the smartcard. This is especially
useful when the network is unreachable, or if the user does not want to
open a network connection.
When set in the Referral Throw mode, PNDS throws an exception at
destination to the client application as soon as it traverses an object
bound to a referral. The client application can choose to open a network
connection, and request from the PNDS the remaining part of the query to
complete the lookup, as well as the address to contact the server.
When set in the Referral Follow mode, PNDS is able to follow referrals
on its own. Without informing the client application that the requested
object is located on a remote server, PNDS requests the hosting terminal
to open a network connection and forward the request.
Data from the PNDS can be updated either by service providers/administrators
from the network, or directly by users themselves from the client application
on the terminal. A security model for access controls will have to be provided
(see section 7). Therefore, it will be
possible to bookmark the result of queries locally on the PNDS smartcard
for next uses.
3.2 Remote Attributes
Due to their tiny size, smartcards have inherent limitations in term of
memory capacity (see section 4). Thus,
we have introduced the concept of Remote Attribute to reference
object attributes which are located remotely on external content servers
(figure 3). Commonly, a reference attribute will
be stored as a URL, but any other addressing schemes can be supported (e.g.
phone number ).
Figure 3 - The Personal Naming & Directory Service
[Section 4] [Table