NAME

       elektra-introduction - an introduction to Elektra

       Elektra  is  a  library  implementing  access  to a global key database. The Global key database provides
       global access to all key databases of all applications in a system that wants to access a  key  database.
       To elektrify an application means to change the application so that it uses Elektra afterwards.

       Information  on  Elektra  can  be found on the website http://www.libelektra.org. For introduction in the
       terminology, make sure to read the glossary elektra-glossary.md.

Why Elektra?

       Configurations, settings and preferences are hierarchical data structures of keys, each consisting  of  a
       name  and  a  value.  They can be used to configure software for the user´s needs. Because these settings
       stay the same across restarts of the program, they need to be stored permanently. In the  beginning  this
       was done with primitive text files. Possibilities to structure the text were added later.

       Nearly  every  system  developed  its own way to read preferences, but some systems can also change them.
       Because the graphical user interface can be tweaked in many ways, the most encompassing  systems  emerged
       from  this  area.  Some  got  a de facto standard for a desktop environment (kconfig, gconfig) or even an
       operating system (Windows Registry, Open Directory). But they have a common problem: they  are  bound  to
       the  platform  for  which they were developed. On the other hand, there are many libraries that do a good
       job in parsing and writing configuration files. These tools are, however, not powerful enough to keep the
       configuration independent from the operating system´s details, for example, how to resolve the file  name
       of the configuration file.

       That  is  where Elektra comes in to fill the gap. On the one hand, Elektra is not tied to any platform or
       operating system. On the other hand, Elektra is powerful enough to be useful immediately for what  it  is
       written for: to access configuration.

Why is it important?

       The  configuration  files  that represent key databases can have binary or humanly-readable formats. From
       the latter, an unmanageable number is established. Developers of programs tend to document the format  of
       the  configuration  file  extensively.  The  configuration  file may give a special flavour to a specific
       program and users frequently need it.

       Sometimes limitations in the configuration file even lead to rewrites of software. For example, inetd has
       a non-modular flat configuration file that is not extensible because of a  limited  number  of  rows.  In
       order  to extend its functionality, the program had to be rewritten with a new approach to configuration:
       xinetd emerged. Both of these projects are now almost defined by their configuration  files  giving  them
       identity  and  separating  them  from  each other. Elektra has introduced backend backends to support the
       storage of key databases in different formats.

       Elektra abstracts configuration so that applications can receive  and  store  settings  without  carrying
       information about how and where these are actually stored. It is the purpose of the backends to implement
       these details. What makes the difference is the situation that every program can access any configuration
       because  of  the  abstraction.  In  the  example of inetd, Elektra allows an elektrified inetd respective
       xinetd to store its configuration in  /etc/inetd.conf  respective  /etc/xinetd.conf.  Additionally,  each
       other program interested in these preferences can access them in a uniform way.

       To  support  a  global  key  database,  a mutual agreement on some level is needed. Elektra provides this
       common layer with its data structures. Each elektrified application lies on top of this abstraction layer
       and it can talk to each part of the global key database using the classes presented next.

                                                    July 2017                            ELEKTRA-INTRODUCTION(7)