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XIXL - Streaming Indices
"Streaming indices" describes the abilities (i) to make index downloading
more efficiently by dividing large indices into smaller ones, which
are then read as needed from the server, and (ii) to change menu
content without reloading the applet and the page. A site-wide
efficient menu strategy will also probably involve compressed indices (ZIP
format indices) and your own server-side scripts for creating
index segments from databases.
- The DRILL command
A command entry of the form "DRILL:index2.txt" causes the
applet to dump the current index and replace it with the
index in "index2.txt". You can combine DRILL commands with
other commands in the same command entry (separated by a
semi-colon), which means that you can, for example, load
a new page into the main browser frame and simultaneously have a new
index loaded into the applet. The DRILL command is available
on all Express, Pro and Pro-X applets.
NB: Some applets (e.g. iMMap Pro, iTree Pro) have their own
DRILL command syntax - please see the individual applet documentation.
- The ADD / INSERT commands
These commands are only available with:
- iSlide Pro-X Tree Type I
- iTree Pro-XQ Powertree
They have the same syntax as DRILL commands, but have a different
effect. A DRILL command dumps the current index and replaces it
with a new one. ADD and INSERT commands add new index segments to
the current one at the position where the ADD or INSERT command
occurs. If a menu entry contains an ADD or INSERT command, a click
on that entry triggers a submenu system (of any complexity or depth)
to be added at that point. Don't forget that the index segment needs
to be downloaded from the server. Depending on the applet in question,
there are various memory optimisation systems which define to what
extent these additions are temporary or permanent.
- How big is a large index?
Applet versions sold from April 1999 onwards
will perform well with indices in excess of 5000 or so entries in a single file.
However the index file for such a large index might take a while to transfer
over some networks (applies to internet; may not apply to many intranets), in
which case it would be wise to ZIP compress it. Customers have reported successully
using large single files in excess of 10,000 entries (without DRILL, ADD and INSERT commands) - the success
of this will depend partly on the characteristics of the network you are
programming for.
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