> On 5/10/06, Gregg Wonderly <[EMAIL PROTECTED]> wrote:
> Satellites typically bill by time (use of the link), not bytes. You
> also normally have carte blanche as to how you use that time, so can
> therefore tweak your protocols (e.g. packet size) to accomodate
> changes in payload size.
I guess it depends on your view of time vs bytes. There is fixed bandwidth
available per time unit. So, in the end, your cost has an upper limit on
bandwidth use, and some sat companies charge higher rates beyond that limit.
> This system replaced (except for the raw data format) a series of
> highly optimized binary formats for configuration & SOH which had poor
> extensibility characteristics, which increased maintenance costs as
> new software had to be deployed anytime a new SOH or configuration
> parameter was deployed. Very painful. RDF/XML/Turtle completely
> resolved that problem, and with an open format for which many tools
> had already been developed. And that reduced development time
> considerably.
I'm not arguing this point, only pointing out that there is an alternate
universe where this type of solution is not always viable. I do use XML for
data flow and for some field data collection. But, there is not always a place
for it.
> > If I coded that in XML, it would likely be an order
> > of magnitude larger in bandwidth.
>
> Probably, but if it's sent infrequently, or the typical document fits
> into your packets, then the advantages can be worth it... even moreso
> for RDF/XML, which provides additional advantages over vanilla XML,
> and was very well suited to configuration & SOH data (because the
> structure is simple).
Many of my customers send data continuously over the satellite links that they
have time/space on, because they have data aquisition requirements that are
designed around the maximum bandwidth that the have and the total amount of
equipment that data is needed. Any significant change in bandwidth will be
noticed by reduced dataflow (the back side is fixed at 9600 for some and 1200
baud for other devices in the field for example).
You have to manage all aspects of the system and be prepared to make intelligent
decisions on data format and flow as needed.
Gregg Wonderly
SPONSORED LINKS
| Computer software | Computer aided design software | Computer job |
| Soa | Service-oriented architecture |
YAHOO! GROUPS LINKS
- Visit your group "service-orientated-architecture" on the web.
- To unsubscribe from this group, send an email to:
[EMAIL PROTECTED]
- Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service.
