Comtech EF Data / Stampede
FX Series Administration Guide - Version 6.2.2
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Chapter: Overview - FX Series
Section: Two-Sided Solution
MN-FXSERIESADM6 Rev 6
1.4
Two-Sided Solution
1.4.1
Cache Differencing
Cache Differencing takes the concept of caching one step further and maintains identical copies of the
browser's cache at the local device and on the FX Series appliance. The FX Series then uses intelligent
differencing technology to understand what data has actually changed, and then transfers only the
changed data. The local device functions normally, but with less data being transferred, you realize
improved utilization of the satellite network, and increased end-user productivity.
Traditionally, pages can be marked as cacheable and will have expiration dates. When they expire they
must be retrieved from the original server, resulting in additional traffic and data being transmitted across
the satellite network. Within a two-sided environment, the FX Series Remote appliance caches all pages
returned to the browser (even pages that are marked as non-cacheable) and performs validation when
needed to ensure that no stale data is returned to the browser. When the browser asks for a page or an
item that has expired or been marked as non-cacheable, the FX Series remote appliance sends a
validation request to the FX Series appliance at the head-end. If the FX Series appliance is aware of the
last page the client cache contains and can compute differences in the page, it sends just the differences
to an expired page or non-cached page. If the differences are too big, or if the FX Series appliance no
longer has retained the last version that the client has, then the entire page is returned and subsequently
cached for future possible differencing. The client in turn reconstructs the requested page, caches it, and
returns it to the browser. Checksums are calculated by the FX Series appliance at the head-end and
verified at the FX Series remote appliance so that pages will never be delivered incorrectly. While this
technique adds value on expired pages, it is extremely effective for dynamic page generation.
An important aspect of Stampede's Cache Differencing is the ability to perform differencing not only on
HTML GET requests but also on POST requests. This is significant because a) responses to posts are always
marked non-cacheable, and b) most applications that are based on SOAP and XML (including most AJAX
applications) issue SOAP requests via the HTML POST command.
1.4.2
Multiplexing of Large Data Objects
The FX Series multiplexes large data objects using Comtech EF Data's patented TurboStreaming™
(multiplexed TCP sessions, patent # 7,543,072) that enables HTTP browser traffic to be intermixed across
multiple "pipelines". All browser activity is optimized, including the network-intensive polling associated
with Web 2.0 and AJAX applications. A key advantage of TurboStreaming is that communication resources
can be shared across multiple applications, and all HTTP requests and responses from any application
(including multiple browsers) are intermixed simultaneously across multiple concurrent sessions.
TurboStreaming serves as a platform for the consolidation and aggregation of all Web-based traffic from a
given user. Multiple HTTP protocol streams are logically aggregated across a few TCP sessions. Individual
objects or pieces of objects can be split into any size and then multiplexed with other object data and
reconstructed as needed SNSPs that deliver mixed payloads consisting of business-critical applications and
data, streaming media, and other network-intensive traffic. The end result is improved throughput and
faster response time for the end-user.
TurboStreaming enables the browser to open multiple pipelines (10s or even 100s) that communicate
with the FX Series remote appliances. All of this data, from all browsers and all browser windows, is
intelligently multiplexed over multiple TCP sessions back to the head-end FX Series appliance. This fully
utilizes all available bandwidth, and enables the browser to function at its full potential. This is only
possible because of advanced, industry leading two-sided acceleration technology.
