7of9 Release 2: First Steps

Introduction

7of9 is an software package for target-related data analysis. It was written to provide an easy to use interface to access the information of the target database, the bunch database, and the gated scalers database simultaniously. An important issue of the development was to completely hide the underlying database hierarchy: The user just has to give the date at which he wants to access the data, and 7of9 automatically takes the right set of databases. Even more, 7of9 is able to synchronize the three databases.
7of9 is fully embedded into the ROOT analysis package, providing easy access to all kinds of data analysis packages.
For even more detailed studies of beam related topics, 7of9 provides an interface to the official HERA database server.

The Concept of the Database Access

The database access is done by so-called EasyTableReaders. An EasyTableReader is an object that knows about the contents of a given database; it is able to read the database values of a given time stamp and writes it to a predefined set of variables.
To scan over a given time interval, each database has its own DBTableIterator, that provides time information of each time stamp and allows the EasyTableReader to access the data. By using a DBTableIterator, it is easy to loop over small as well as large data sets, even if the chosen time interval exceeds one database file; the iterator knows where to find the next database and automatically connects to it. So the user does not need any information about where the database files are stored, what data is stored in them etc.
Currently four different types of DBTableIterators provided:

TargetTableIterator access to the target database

BXTableIterator the bunch database

BXSpectrumIterator the bunch spectra

SISTableIterator for accessing the gated scalers information
Using an DBTableIterator is quite simple; just loop over the time interval you are interested in. If DB is a pointer to your TargetTableIterator, you could possibly write
```
Date start ("2000/06/01 13:00:20");
Date end   ("2000/08/12 00:10");

for (DB->init(start); DB->valid(end); DB->next()) {
  // access your data...
  cout << "interaction rate: " << DB->iaMean << endl;
  cout << "unixtime:         " << DB->unixTime() << endl;
}
```
The first two lines of the code make use of 7of9's Date class. It is an interface to handle dates in a convenient way. The class makes use of operator overloading and provides quite powerful methods to play with dates and time-strings.
The TargetTableIterator is initialized by just providing a start date; the DB->next() method simply increments the database in steps of one second. Of course it is possible to go in steps of n seconds by using DB->next(n) instead.
The DB->valid() method tests for every time we pass the loop wether or not we already reached the end of our predefined time interval.
Inside the loop you can access the data of the target DB for the given time stamp. As an example we print out the mean interaction rate as well as the unixtime. Which variables are provided to access the data can be found in the corresponding header file (RELEASE2/src/iterators/TargetTableIterator.H)

Methods for Common Use and User Defined Code

A good starting point to see how to use the DBTableIterators is the pool of methods designed for common use. All of them reside in the class moBase (RELEASE2/src/main/moBase.H). There are methods to produce standard overview plots (e.g. moBase::ov(), moBase::BXov(), moBase::BXSov()) as well as functions providing useful information about the target or beam status (e.g. moBase::wireIsIn(), protonsIn()). Functions to produce standard root trees out of the databases are given, too.
All these functions are documented in quite some detail in the Reference Manual.

Private analysis code should always go to the file RELEASE2/src/mail/mo.C. The class mo is a public derivative of moBase, and therefore inherits all properties of it.
After starting 7of9 via BorgTransmitter, an object of mo is instantiated automatically. You can access it in 7of9 via m. For example:
```
m->BXov("2000/06/01", "2000/07/10 13:20")
```
gives you an overview plot of the bunch database for the given time interval.
```
m->makent("demo", "1999/01/01", "2000/09/01")
```
creates a ROOT-Tree (stored as RELEASE2/rootnt/seven_demo.root) including all the relevant target information of the last two years.
```
m->ThisIsMyStuff()
```
calls your private analysis method mo::ThisIsMyStuff().

last change on Okt 30, 2000 by Christopher.van.Eldik@desy.de

TargetTableIterator	access to the target database
BXTableIterator	the bunch database
BXSpectrumIterator	the bunch spectra
SISTableIterator	for accessing the gated scalers information