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| Lightstreamer Server |
Lightstreamer Server is
a push engine that delivers real-time data through the HTTP (or HTTPS)
protocol to any types of clients (Web pages, Flex application,
thick applications, etc.).
Lightstreamer Server is a stand-alone process, which has a direct control over the operating system's TCP/IP stack and
the threading model, to optimize the data transmission as much as possible. The Kernel of Lightstreamer Server has the
role of distributing the data to the clients in a reliable and
efficient way, offering unique features such as
Bandwidth & Frequency Control and
Adaptive Streaming.Lightstreamer implements many sophisticated mechanisms to pass through any firewall and proxy without the
risk of security policy blockages. |
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| Lightstreamer Adapters |
When a Client
creates a Lightstreamer session, it can specify an Adapter
Set to use. An Adapter Set is made up of a Metadata Adapter
and one or multiple Data Adapters. An Adapter is a custom
server-side component developed by implementing some provided
interfaces (based on Java API, .NET API, or on
plain TCP sockets through the Adapter Remoting
Infrastructure). The role of a Metadata Adapter is
to manage the policies applied to a user's session. It validates
the authentication credentials sent by the Client and enforces
the appropriate quality of service (in terms of allocated
bandwidth and frequency). It validates each subscription request
to decide whether the user is entitled to subscribe to a certain
item or not.
Each Data Adapter is a connector that interfaces Lightstreamer
Server with a data source. The Data Adapter receives data flows from
any back-end systems (information providers, data feeds, databases, etc.) and makes
them available to Lightstreamer Server for controlled delivery
to individual users.
Being able to handle an arbitrary number of different Data Adapters and Metadata Adapters
(grouped into Adapter Sets), it is possible to integrate
heterogeneous sources of information while maintaining a single
point of access to the streaming/push channel. |
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Lightstreamer Deployment |
The following diagram shows a typical scenario in which the real-time data is distributed to Web browsers.
A
Lightstreamer Server and a normal Web Server are deployed in the DMZ network
(accessible to Internet clients). Lightstreamer gets the data and metadata from the back-end
systems, which are usually protected by a second firewall. The Web browser gets the static
part of the Web pages
from the Web Server, but receives the real-time updates
from Lightstreamer Server. See Technology – Client Side to read more about how the browser handles
the push updates. |
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It is possible to create a cluster of Lightstreamer Servers by using any Web load-balancing appliance,
in order to achieve load-balancing and fail-over. If one of the machines in the cluster fails, the clients
will reconnect to another machine. The recovery is transparent to the users,
while full data coherency in maintained. |
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