Published on 2005-11-15 16:28:26
Lightstreamer Server
Lightstreamer Server is the push/streaming engine, that handles the physical connections with the clients. It streams data through HTTP and HTTPS connections to any type of client (Web clients, application clients, etc.). A stand-alone process, which does not rely on web servers or application servers. This approach was taken in order to have direct control over the operating system's TCP/IP stack and to optimize the data transmission as much as possible. The Kernel of Lightstreamer Server has the task to distribute the data to the clients in a very reliable and efficient way, offering unique features like Bandwidth & Frequency Control and Adaptive Streaming.
Bandwidth control
For each user, Lightstreamer can allocate a maximum bandwidth that is dedicated to the streaming channel. For example, if it is required that a certain user cannot exceed a bandwidth of 10 kbps, Lightstreamer will filter the data in such a way as to ensure that the streaming connection with that user always remains below 10 kbps.
The system is also able to allocate a maximum update frequency for each user/item combination. For example, it is possible to configure the profile of a certain user so that they do not receive more than 2 updates per second for a certain subscribed item (piece of data).
Adaptive streaming
Internet connections are often unable to offer a guaranteed bandwidth. This means that the ability to allocate a maximum bandwidth to each user may not be sufficient to ensure that the push connection is managed in the best way possible. The system has to be able to take into account exactly how much bandwidth is actually available at any moment in time.
Adaptive streaming is particularly useful for connections that are notoriously unstable and variable, such as those on the GPRS network. Let's assume that the user starts a push session on their GPRS smartphone (using one of the many mobile clients made for Lightstreamer). If at a certain point the GPRS signal deteriorates and the effective bandwidth narrows Lightstreamer Server detects what is happening and adapts the streaming in a dynamic way to the new network conditions, even going so far as to suspend the transmission of data in the event that no bandwidth is available at all.
Yet another great commercial application joining the AJAX market, I saw a few of their customers specially from the italian market mainly acting in Finance & Market Data Distribution. In the demo application also there is different kind of advanced usage of Lightstreamer such in News, Interactive Messaging, Monitoring, Sports ...
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