<?xml version='1.0' encoding='utf-8' ?>
<!DOCTYPE chapter PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN" "http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd" [
<!ENTITY % BOOK_ENTITIES SYSTEM "AppStream.ent">
%BOOK_ENTITIES;
]>
<chapter id="chap-AppStream-About">
	<title>About AppStream</title>

	<section id="about-whatis">
		<title>What is AppStream?</title>

		<para>
			AppStream is a cross-distro effort for building Software-Center applications and enhancing metadata provided by software components.
			It provides specifications for meta-information which is shipped by upstream projects and can be consumed by other software. The meta-information
			includes data which is interesting to display in software centers and is mainly useful for end-users, as well as descriptions about the public
			interfaces a software component provides, which is mainly useful for developers, 3rd-party software installers and for automatically installing
			missing components on a distribution, for example missing firmware.
		</para>
		<para>
			Distributors provide metadata as well, which describes all components available in a software repository. That data is composed of the upstream-metainfo
			and some other sources.
			AppStream also provides specifications for things like a screenshot-service, application ratings &amp; reviews etc.
			All AppStream distro-repository data is stored in a Xapian database, which then contains information about all available components in the distribution's
			software repositories.
		</para>
		<para>
			All parts of AppStream are distro-agnostic (with exception to some metadata which is used to generate the Xapian application cache), and therefore
			AppStream makes it possible to build distro-agnostic application management tools.
		</para>

		<section>
			<title>Architecture</title>

			<para>
				<mediaobject>
					<imageobject>
						<imagedata fileref="images/architecture.png" format="PNG"/>
					</imageobject>
				</mediaobject>
			</para>
		</section>
	</section>

</chapter>
