Browse Prior Art Database

A SIP-based Synchronization Server

IP.com Disclosure Number: IPCOM000022498D
Original Publication Date: 2004-Apr-25
Included in the Prior Art Database: 2004-Apr-25
Document File: 2 page(s) / 45K

Publishing Venue

Siemens

Related People

Juergen Carstens: CONTACT

Abstract

In a classical Information System Software, each client is connected to the database from which it retrieves or where it stores information. The information is usually stored in the cache memory. Two problems emerge in such systems. Firstly, some pieces of information on the database could be accessed and modified by several clients at the same time. It is necessary to ensure that only one application at a time can change a data item. The adequate mechanism used by DBMS (Database Management System) for the sharing of data is concurrency control and locking. Secondly, the information stored in the memory of a client can be out of date if another client has modified the relative information on the database. This problem is referred to as cache synchronization.

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A SIP-based Synchronization Server

Idea: Olivier Roger, FR-Lannion

In a classical Information System Software, each client is connected to the database from which it retrieves or where it stores information. The information is usually stored in the cache memory. Two problems emerge in such systems.

Firstly, some pieces of information on the database could be accessed and modified by several clients at the same time. It is necessary to ensure that only one application at a time can change a data item. The adequate mechanism used by DBMS (Database Management System) for the sharing of data is concurrency control and locking.

Secondly, the information stored in the memory of a client can be out of date if another client has modified the relative information on the database. This problem is referred to as cache synchronization.

At present, there are several solutions for the cache synchronization. For example, it is possible to detect conflicts when a client tries to write information on the database. Another way to synchronize distributed databases is provided by the SCSP (Server Cache Synchronization Protocol).

Here, it is proposed to install an additional server called Synchronization Server that is dedicated to both cache synchronization and concurrency control and locking. This server provides the following features:

* SIP (Session Initiation Protocol) for communication with the clients

* Storage of a list of the last modifications (variable length, depends on the memory)

* The server automatically notifies the clients about all modifications of data items, but does not update the information stored on the clients.

* Clients can subscribe/unsubscribe as observers of the information.

* Only signaling messages. No data is transmitted by the Synchronization Server.

Only the information about the modification of an object is notified. Therefore, it is important to notice that the proposed concept requires the possibility to uniquely identify any object of the client e.g. having a unique ID from the database tab...