Developing ESP Web Pages for WebCenter › Anatomy of an ESP

Anatomy of an ESP

An ESP may contain a mixture of ESP directives, included HTML fragments, HTML, JavaScript, and Cascading Style Sheet (CSS) definitions. When an ESP is fetched by the web server, it goes through the following processing:

1. All <!--#Include … --> directives are resolved by the include processor, fetching the included HTML fragments as required, resulting in source code where all include directives are converted to their fully-expanded source code.
2. The web page is then parsed with the ESP processor, executing all <% … %> ESP directives that could possibly result in the execution of an NCL or Object Management Language (OML) procedure. The ESP directives are removed from the source at this point and can be replaced with ESP-generated HTML or JavaScript source.
3. The web page, which now only contains HTML, JavaScript, and possibly CSS statements, is then sent to your web browser.
4. The web browser, as it renders the page, processes any in-line JavaScript statements. This could potentially create more HTML to be rendered by the browser.
5. The web page is delivered and the HTTP socket connection is closed.