The document describes various container classes in C++ like cQueue, cArray, and histograms that can be used for recording simulation data in OMNeT++. It provides examples of using cOutVector to record time series node energy data, cHistogram to record node lifetime in a histogram, and the eventlog file to view events in a sequence chart. These classes and techniques allow modeling and visualization of simulation results in OMNeT++.

1. By
Mohammed Amer Al-Batati
2012

2.  cQueue is a container class that acts as a queue.
 The basic cQueue member functions:
 insert(obj), inserts an object into the queue head.
 pop(), returns and removes object from the front.
 remove(obj), removes that object from the queue.
 length(), returns the number of items in the queue.
 empty(), tells whether there is anything in the queue.
 insertBefore(obj_where, obj_what)
 insertAfter(obj_where, obj_what)
 front(), returns pointer to the object at the front.
 back() , returns pointer to the object at the back.

3.  cQueue Example:
 Iterators

4.  cArray is a container class that holds objects derived from cObject.
 cArray works as an array, but it grows automatically when it becomes
full.
 The basic usage:
 cArray array("array"); // Creating an array
 int index = array.add( obj ); // Adding an object
 int index = array.find(obj);// Finding an object
 array.remove (obj)// Remove an object
 Iteration
for (int i=0; i<array.size(); i++)
{
if (array[i]) // is this position used?
{
}
}

5.  There are two main types of outputs: vectors and
scalars.
 output vectors are to record time series data and
output scalars are supposed to record a single value per
simulation run.
 Let’s record the node power after every transmission
operation. To do that add the following:
1. cOutVector TxEnergy;// in Node.h
2. TxEnergy.setName("NodePower");// in Node.cc (initialize())
3. TxEnergy.record(energy);// after updating node energy
 Save, build, and run.

6.  A folder called “results” will be generated.
 Click one of VEC files to generate an analysis file (.anf).
 Select “result” as parent folder -> name it-> click finish.

7.  Click Wildcard to add all other VEC files in single ANF
file.
 Browse data to get the following results

8.  You may want to record the distribution as a histogram
(not as a time series).
 Syntax: cHistogram hData;
 hData.collect(value);// to insert a new value.
 Other functions can be used to get the statics, for
example:
hData.getCount(), hData.getMin(),
hData.getMax(), hData.getMean(),
hData.getStddev(), hData.getVariance(),
hData.getSum(), hData.getSqrSum().

9.  Let’s record node life time, which is the time that a
node takes before it dies:
1. At Node.h
2. At Node.cc

10.  Save, Build and run
 Play with the properties to get:

11.  An eventlog file contains a log of messages sent during
the simulation and the details of events that prompted
their sending or reception.
 The Sequence Chart displays eventlog files in a
graphical form.
 Add: record-eventlog = true # In omnetpp.ini
 Save and run.

12.  ELOG files will be generated.
 Double-Click one of them to watch the sequence chart.