== Testbed Tour ==

[[TOC(Tutorials/a0Basic*)]]


=== Developing a Script for an Experiment ===

If you are a new OMF users, you may want to read the short [http://mytestbed.net/projects/omf/wiki/An_Introduction_to_OMF OMF System Overview] and/or [http://mytestbed.net/projects/omf/wiki/UsageOverview the Experiment Life-cycle Overview]. To run an experiment on the ORBIT testbed, in addtion to all the steps from [wiki:Documentation/GettingStarted getting started], a user needs to first describe the experiment in a ''script''. This ''script/experiment description'' is then passed on to a '''Experiment Controller''', which will use it to run and control the experiment execution. This process is illustrated in figure 1. 

This script contains the experiment configuration and scenario.  More precisely, it includes: 
 * a description of the required resources (e.g. nodes on the testbed, applications to run),
 * their initializations and optional associations (e.g. nodeX is connected to NodeY, all nodes use channel 6 of 802.11g), 
 * a description of their operation throughout the experiment duration (e.g. applicationX starts at T0 and run for 60sec, nodeY switch wireless configuration after 100sec).  

ORBIT experiment scripts are written using the Ruby scripting language. However, a user does '''not''' necessarily need to be familiar with Ruby to be able to write and run simple experiments. The only prerequisite skills are some prior basic knowledge and practice of any other scripting and/or programming languages (e.g. python, perl, c, java,...). Of course, to be able to develop more complex experiments a user will have to learn basics of Ruby and read about ORBIT-specific Ruby methods at some stage (more on these two issues at the end of this tutorial).

[[Image(OMF-User-View.png)]]
[[BR]]Figure 1. Execution of an Experiment from a User's point-of-view