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Satellite/cable is basically a "push" approach where everything is sent out
and it is up to the user's computer to collect all data which is needed now
or might ever be wanted in the future. Further, it requires the user to
implement practices to maintain continuity of the feed and data even under
the most unfavorable conditions. Managed well, such services (particularly
satellite based) provide the trader with a continuous, reliable and complete
stream of data suitable for any trading objective ranging from scalping to
position trading.
Conceptually, internet is a "pull" approach where data is brought to the
user's computer only when it is needed. Good implementation requires that
whatever data the user may need is available on the remote servers, that the
servers are capable of organizing the data in the form required by the user,
and that the data be compressed for maximum transmission efficiency. In the
case of trading data, the delivery mechanism must provide a means of
notifying the servers of what data the user is currently using so that the
data is kept up-to-date - an element of "push" and what data the user is no
longer using so that bandwidth is not wasted. While the internet has
continued to improve in reliability, it remains subject to bottlenecks and
failures so reliability of the data stream will be a function of the
redundancy of servers and locations at which the servers are connected to
the internet backbone as well as the quality of the user's ISP and ISP
connections to the backbone. Managed well, with appropriate contingency
procedures, a well-designed internet based feed can provide a data stream
suitable for virtually any trading objective including scalping.
Speaking from first-hand experience: satellite/cable to internet based data
feed is a change in paradigm which many of the internet data feeds have not
managed well, especially Signal On-Line. SOL lacks breadth in the data which
can be requested on demand - a maximum of 500 symbols can be designated for
retrieval and the real-time version provides no delayed data from exchanges
for which the user does not pay real-time exchange fees. SOL also lacks
depth in the data which can be requested on demand - generally only a few
days of intraday tick data is available for construction of intraday charts,
thus the user know ahead of time what data will be required in the future or
make external arrangements to acquire historical data. Finally, SOL appears
to lack an efficient transmission mechanism - when the user asks for 30
minute bars, the server appears to send out all ticks for each bar rather
than constructing the bars at the server and sending out the just the
d/t/o/h/l/c/v/oi for each bar. Obviously, third-party software which is
designed for tick based feeds, must be redesigned to request bars of the
desired length supplemented by tick update and to notify the server as each
symbol is being used/discarded.
Unfortunately, the availability of well-designed internet feeds and
compatible software, remains rather limited - I have identified only two
(but continue to keep an eye out for more): QCharts/QFeed at www.quote.com
supports several 3rd party packages and NexTrend at www.nextrend.com offers
a more complete charting package. The good news is that advances in both
internet data feed and compatible software seem to be coming very quickly -
a year ago I could find none.
Earl
-----Original Message-----
From: Robert W Cummings <robert.cummings@xxxxxxxxxxxxxxxx>
To: Omega-list@xxxxxxxxxx <Omega-list@xxxxxxxxxx>
Date: Monday, April 12, 1999 11:03 PM
Subject: Switch?
>
>DBC Corp. sent me a pamphlet trying to persuade me to which from BMI to
>Signal via the Internet. They make reference to the Y2K issue but don't say
>BMI is not compliant. Is this a warning shot that DBC is getting ready to
>get rid of BMI or maybe sell it. Maybe now trying to get all the current
>clients before they do? Sounds like DBC might be getting out of cable
>delivered data and go strictly with data delivery on the Internet?
>
>
>Robert
>
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