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)