Simple Module HttpController

C++ definition

A controller object for OMNeT++ simulations which use the HttpTools browser and server components. A single controller must exist at the scenario level in each simulation.

The purpose of the HttpController object is to support the server and browser components. A single controller instance must exist in all scenarios in which the browser and server components are used. Server components register their URL, OMNeT++ module name and listening port with the controller upon initialization. The controller serves as a lookup service for OMNeT++ module names from the URLs used to identify the Web server instances. It also provides a random Web site lookup facility, used by the browser component in its random browsing mode. Uniform and Zipf distributions are currently supported for random server selection. The controller parameters are defined in a XML file, as previously discussed for the server and browser components. The controller supports popularity modification events for individual sites. Such events are defined in a script file, assigned to the controller by an initialization parameter, which can be used for modeling a variety of situations involving dynamically changing server popularity. A popularity modification event at a time T_init causes a site to be added to a custom selection list. A random site request from a browser will then yield a hit from the custom list with p_c=sum(p_i), where p_i is the enhanced selection probability of site i on the list. A particular site i is selected from the list with p=p_i/p_c. Conversely, a site is selected from the general population, using its assigned random distribution, with $p_p=1-p_c. The special probability of a site can be amortized by a constant alpha for each hit, eventually reducing it to zero, at which time it is removed from the special list.

Author: Kristjan V. Jonsson

Usage diagram:

The following diagram shows usage relationships between types. Unresolved types are missing from the diagram.

Inheritance diagram:

The following diagram shows inheritance relationships for this type. Unresolved types are missing from the diagram.

Networks:

Parameters:

Source code:

//
// A controller object for OMNeT++ simulations which use the HttpTools browser and
// server components. A single controller must exist at the scenario level in each
// simulation.
//
// The purpose of the HttpController object is to support the server and browser components.
// A single controller instance must exist in all scenarios in which the browser and server
// components are used. Server components register their URL, OMNeT++ module name and listening
// port with the controller upon initialization.
// The controller serves as a lookup service for OMNeT++ module names from the URLs used to
// identify the Web server instances. It also provides a random Web site lookup facility, used by
// the browser component in its random browsing mode. <i>Uniform</i> and <i>Zipf</i> distributions
// are currently supported for random server selection. The controller parameters are defined
// in a XML file, as previously discussed for the server and browser components.
// The controller supports <i>popularity modification events</i> for individual sites.
// Such events are defined in a script file, assigned to the controller by an initialization
// parameter, which can be used for modeling a variety of situations involving dynamically
// changing server popularity.
// A popularity modification event at a time T<sub>init</sub> causes a site to be added to a
// custom selection list.
// A random site request from a browser will then yield a hit from the custom list with
// p<sub>c</sub>=sum(p<sub>i</sub>), where p<sub>i</sub> is the enhanced selection probability
// of site <i>i</i> on the list. A particular site <i>i</i> is selected from the list
// with p=p<sub>i</sub>/p<sub>c</sub>. Conversely, a site is selected from the general population,
// using its assigned random distribution, with $p<sub>p</sub>=1-p<sub>c</sub>.
// The special probability of a site can be <i>amortized</i> by a constant <i>alpha</i> for
// each hit, eventually reducing it to zero, at which time it is removed from the special list.
//
// @author  Kristjan V. Jonsson
//
simple HttpController
{
    parameters:
        string events = default("");          // Popularity modification events defintion file.
        string eventsSection = default("");   // Section within the popularity modification file, if one is defined.
        xml config;                           // XML configuration file.
}

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