Specifications

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Cisco Internet Streamer CDS 2.0-2.3 Software Configuration Guide
OL-13493-04
Chapter 1 Product Overview
Content Delivery System Architecture
The Internet Streamer function is implemented as a set of protocol engine applications. The protocol
engine applications are:
• Web Engine
• Windows Media Engine
• Movie Streamer Engine
• Flash Media Streaming Engine
Web Engine
All HTTP client requests that are redirected to a Service Engine by the Service Router are handled by
the Web Engine. On receiving the request, the Web Engine uses its best judgment and either handles the
request or forwards it to another component within the Service Engine. The Web Engine, using HTTP,
can serve the request from locally stored content in the CDS or from any upstream proxy or origin server.
An HTTP client request that reaches the Service Engine can either be from a Service Router redirect or
from a direct proxy request.
On receiving an HTTP request for content, the Web Engine decides whether the content needs to be
streamed by the Windows Media Engine, and if so, hands the request over to the Windows Media Engine,
otherwise the request is handled by the Web Engine.
Policy Server Integration
The policy control server, a third-party PCMM-compliant system, ensures guaranteed bandwidth for
multimedia data delivered over broadband networks. The Web Engine communicates with the policy
server by means of Internet Content Adaptation Protocol (ICAP) and HTTP to set and monitor QoS
attributes for each client session and whether access should be denied.
Using ICAP, the Web Engine determines whether the bandwidth reservation can be allocated for this
client or access should be denied. The policy server uses the cookie generated by the web portal and the
client’s IP address to make the decision and replies accordingly to the Web Engine.
Using HTTP, the Web Engine communicates the start and teardown of the request to the policy server.
Bandwidth reservation is performed when the download starts, and once the download is complete, the
Web Engine sends a teardown message to the policy server.
The Web Engine uses PCMM to interact with the policy server to allocate guaranteed bandwidth for
authenticated client requests for content. The PCMM integration allows the granting of QoS for the
session as well as conditional access protection of the content.
Upon receiving permission from the policy server, the Web Engine generates a URL signature and
appends it to the requested URL; it then embeds the new URL in an .asx file and sends the file back to
the client. The file consists of the signed URL with RTSP and HTTP options. For RTSP and HTTP
streaming, the Windows Media Engine communicates with the policy server for bandwidth commitment.
If RTSP and HTTP streaming fail, the client device begins HTTP progressive download of the file. The
Web Engine handles the QoS for HTTP progressive download requests.
The signed URL adds additional security. The URL signature generation is based on a key that is a shared
secret between the component generating the URL signature and the component validating the URL
signature. The URL signature can be generated by the Web Engine, another component external to the
Service Engine, or the web portal.
Cache Fill Operations
The Web Engine interfaces with the storage function in the Service Engine to determine whether the
content is present locally or whether the content needs to be fetched from either an upstream Service
Engine or the origin server.