Part 5: Performance, There is a Lot Going On Here
Yes, there is a lot going on in a web server, especially one that supports
active page content with an embedded programming language. Before you think
that this must be a real dog, PicLan-IP uses a number of techniques to
insure that things run smoothly.
Server-Side Caching
PicLan-IP makes extensive use of temporary files to remember work that
it has already performed. If you save an HTML page that contains embedded
MV/Basic code, the PicLan-IP web server will only parse and compile the
page the first time that it is accessed. Subsequent accesses will use the
results of the previous parse/compile step with essentially no delay. This
means that you web developers will see a delay when a page is compiled,
but from there on out,the page responds at full-speed.
This server-side caching is intelligent and fully automatic. You can
freely change content at any time and the PicLan-IP web server will automatically
react to page changes re-building active content as necessary.
The second aspect of server-side caching is the actual storage of web
content, including HTML, HTML with embedded content, graphic files such
as GIFs and JPEGs, and others. The PicLan-IP web server will pre-compute
as much information about a document the first time that the document is
referenced so that subsequent references run as quickly as possible. This
includes resolving web document/MIME types, pre-converting text into web
CRLF line seperator format from the MultiValue AM line seperator format,
pre-calcuating web time/date format strings, and other operations. This
makes the PicLan-IP web server very responsive by elimanating most of the
processing of individual web pages for most page hits.
Space at a Premium
Server-side caching does have it's costs. In the case of PicLan-IP, the
tradeoff of performance vs. space is the obvious outcome. PicLan-IP will
buy performance with disk space. HTML web documents with embedded content
may occupy 3-6 times as much system storage space as their original document
and graphics files grow by 2-3 times. For most web sites, document size
is not usually a concern. 10 Megabytes of HTML pages is a huge amount and
even multiplying this by 4 is still only 40 Megabytes of disk space. All
in all paying for speed with a little extra disk space seems to be a good
tradeoff.
Intelligent Active Pages
The manner that HTML pages that include embedded MV/Basic code also effects performance
greatly. When an HTML page with MV/Basic code is detected, a standard MV/Basic
subroutine is generated that includes all of the in-line MV/Basic statements along
with machine generated statements that actually perform the merge operations for
insertion points. In most cases, the operation of running a generated subroutine
includes the code that you write, some HTML quoting operations, and a single concatenate
statement to generate the final page's contents. Because of the nature of machine
generated code, it would be difficult for most human programmers to write a subroutine
that executed more efficiently.
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