path: root/doc/manual/introduction.xml

<chapter>
  <title>Introduction</title>

  <sect1>
    <title>The problem space</title>

    <para>
      Nix is a system for controlling the automatic creation and distribution
      of data, such as computer programs and other software artifacts.  This is
      a very general problem, and there are many applications that fall under
      this description.
    </para>

    <sect2>
      <title>Build management</title>

      <para>
	  Build management tools are used to perform <emphasis>software
	  builds</emphasis>, that is, the construction of derived products such
	as executable programs from source code.  A commonly used build tool is
	Make, which is a standard tool on Unix systems. These tools have to
	deal with several issues:
	  <itemizedlist>
	  <listitem>
	    <para>
	    </para>
	  </listitem>
	  </itemizedlist>
      </para>

    </sect2>

    <sect2>
      <title>Package management</title>

      <para>
	  After software has been built, is must also be
	<emphasis>deployed</emphasis> in the intended target environment, e.g.,
	the user's workstation.  Examples include the Red Hat package manager
	(RPM), Microsoft's MSI, and so on.  Here also we have to deal with
	several issues:
	  <itemizedlist>
	  <listitem>
	    <para>
	      The <emphasis>creation</emphasis> of packages from some formal
	      description of what artifacts should be distributed in the
	      package.
	    </para>
	  </listitem>
	  <listitem>
	    <para>
	      The <emphasis>deployment</emphasis> of packages, that is, the
	      mechanism by which we get them onto the intended target
	      environment.  This can be as simple as copying a file, but
	      complexity comes from the wide range of possible installation
	      media (such as a network install), and the scalability of the
	      process (if a program must be installed on a thousand systems, we
	      do not want to visit each system and perform some manual steps to
	      install the program on that system; that is, the complexity for
	      the system administrator should be constant, not linear).
	    </para>
	  </listitem>
	  </itemizedlist>
      </para>
    </sect2>

  </sect1>

  <sect1>
    <title>The Nix system</title>

    <para>
      ...
    </para>

    <para>
      Existing tools in this field generally both a underlying model (such as
      the derivation graph of build tools, or the versioning scheme that
      determines when two packages are <quote>compatible</quote> in a package
      management system) and a formalism that allows ...
    </para>

    <para>
      Following the principle of separation of mechanism and policy, the Nix
      system separates the <emphasis>low-level aspect</emphasis> of file system
      object management form the <emphasis>high-level aspect</emphasis> of the
      ...
    </para>

  </sect1>

</chapter>

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