FOKUS XML Document Management Server

An OMA compliant XML Document Repository

The XML (Extensible Markup Language) Document Management defines a common mechanism that makes user-specific service-related information accessible to the service enablers (e.g., PoC (Push-to-Talk over Cellular), IM (Instant Messaging), Conferencing, etc.). Such information is stored in the network at the IMS Application Layer on an XML Document Management Server (XDMS) where it can be located, accessed and manipulated.

The XML Configuration Access Protocol (XCAP), as defined by the IETF in RFC 4827, has been chosen as the common XML Document Management protocol. The following figure illustrates the role of XDMS as IMS service enabler:

XDMS as IMS service enabler

One of the purposes of a XDMS as specified by the Open Mobile Alliance (OMA) is to manage groups, contact lists and access lists. A contact list is a kind of address book that may be used by e.g. PoC users to establish an instant talk session with other PoC users or PoC groups.

 A user may have one or several contact lists including identities of other PoC users or PoC groups.Contact list management includes operations to allow the XML Document Management Clients as myMONSTER TCS to store and retrieve the contact lists located in the XDMS.

Access lists are used by the end user to control the access on NGN services or user related data of the end user e.g. black- and white-lists approach. Furthermore a SIP-based Subscription mechanism as defined in RFC 3265, allows users or applications to be notified of document changes.

Features of the FOKUS XDMS

The FOKUS XDMS is an enabler that stores and manages user personal profile, privacy and group membership information by using standard based interfaces. It provides an extensible data model using XML schema, which allows application servers to easily access and manipulate XML documents. The FOKUS XDMS supports all valid XML schemas and not only the common OMA standard XML schemas. It is a key NGN Telco service enabler, which can be used to deliver innovative, instantaneous, person-to-person applications.

The FOKUS XDMS can be used for the central storage of application specific user data. A client can access and manipulate XML document using the HTTP – based XCAP interface. This client can either be an application that requests that information on behalf of a user or a client at the end device. The following figure depicts the basic architecture of the FOKUS XDMS.

Architecture of the FOKUS XDMS

The XCAP Handler supports next to the general XDM functions also a JavaScript Object Notation (JSON) (RFC 4627) transformation. In addition to the XCAP Handler, a POST request handler enables the transformation of existing documents in any kind of text document type, using XSLT technologies. The W3C XQuery standard (W3C) can be used to search for information in single documents and even through a whole collection of documents.

The implementation of the FOKUS XDMS enables the above-described functional modules and is mainly tested on the SailFin SIP Application Server. As a native XML Database for the storage of XML data two different open source databases can be used the Apache Xindice or the eXist database.

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