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Typically the user interface of a WWW application is based on constructing HTML output pages dynamically
inside the application module. However, hardcoding layout design into application code level
is rarely a feasible approach. To gain proper isolation of layout and coding tasks the
construction of HTML page formats must be separateable from the writing of the application source,
often distributed to different personnel. The expected lifetime of a HTML user interface is also
a lot shorter than the lifetime of the actual application mechanisms.
WAPI allows the HTML pages displayed by a WWW application to be defined using a dynamic template
technique. Standard HTML language and editor tools may be used to design page layouts. Insertion of variable
data into proper positions is achieved by using variables, conditional statements, loop structures
and other features of the WAPI HTML page template language. The HTML template files constructed in
this manner are then dynamically interpreted run-time by the application module to produce final
program output on user browser.
Since HTML page templates are individual physical files like normal static HTML pages, modification of
interface layout of an application is extremely easy. WAPI provides fast interpretation of templates
during application execution, even when a very large number of variable references and conditions
exist in the source template.
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Message-oriented integration of WWW applications and operational databases is the most secure,
effective and flexible approach for browser-oriented solution design.
Distributed Transaction System
can be used as the underlying Middleware for easy and reliable intersystem connectivity.
Exchanged user application data is formatted into messages using some predefined message structures.
These structures can be modelled in an abstract manner using WAPI message definition language.
Order, type and length of individual data fields and list structures is described in a definition
file that is driven through a precompiler. The produced source module is taken into the actual
application project to get abstract access into message data. No direct bindings into physical message field
positions and types are required in the program source, but just references using defined field
names. Change of message format no longer implies a requirement to change the application source,
just an update of WAPI message definition and module rebuild.
WAPI HTML page abstraction and data message abstraction techniques may be used either separately
or combined. The ultimate advantage is achieved via automatic mapping of message data fields into variables
used in a HTML page template. Such transparency will make the actual program code required very small
and impressively flexible.
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