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Naming and directory services are traditionally supported by network servers and are provided to users as part of their network and service provider subscription.

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 ( figure 3).

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 :

3.1 Three Modes of Operation

The PNDS leverages the LDAP concept of referrals by handling three modes of operation.
  1. 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.
  2. 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.
  3. 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.
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.

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 [1]).
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Figure 3 - The Personal Naming & Directory Service

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