\HeaderA{RepositoryThemes}{Repository Themes}{RepositoryThemes}
\aliasA{getReposThemePkgs}{RepositoryThemes}{getReposThemePkgs}
\aliasA{loadRepThemes}{RepositoryThemes}{loadRepThemes}
\aliasA{repositoryThemes}{RepositoryThemes}{repositoryThemes}
\aliasA{repThemeNames}{RepositoryThemes}{repThemeNames}
\aliasA{themes}{RepositoryThemes}{themes}
\keyword{utilities}{RepositoryThemes}
\begin{Description}\relax
Repository themes allow a repository maintainer to specify a set of
packages within their repository that can be downloaded as a
collection by other users.  Clients using \code{reposTools} can
specify one of these themes to their installation calls, acquiring
the particular set of packages listed as being part of the theme.
\end{Description}
\begin{Section}{Basic Information}
The purpose of repository themes is to allow various subsets of a
repository's packages to be downloaded easily and conveniently.  As
the size of a repository grows, there are likely to be small
collections of packages which have a logical connection to each other
which users will often want to download together, but it can become
unwieldy to do so using \code{\LinkA{install.packages2}{install.packages2}} in the
traditional manner.  By specifying a theme, all the
desired packages can be downloaded quickly and easily.

Themes have a basic structure, which is modeled by the class
\code{\LinkA{reposTheme-class}{reposTheme.Rdash.class}}.  Every theme has a name to reference
it by, a description, information about the repository it is a part
of, as well as a list of \code{\LinkA{pkgInfo}{pkgInfo}} objects defining the
packages that are included in the theme.  This definition is then
written in a XML file by the repository maintainer (or using the XML
authoring function \code{\LinkA{writeThemesXML}{writeThemesXML}}) which is in turn read
in by the \code{\LinkA{genRepos}{genRepos}} function during repository generation
to create a repository infrastructure file named
\code{reposThemes.rda} that allows client functions to see
which themes are available from a repository.

For the client side user, if one uses the \code{theme} argument to
\code{\LinkA{install.packages2}{install.packages2}}, then \code{reposTools} will seek out
the specified theme(s) in the set of repositories it is instructed to
look at and download any packages being marked as being part of that
theme.
\end{Section}
\begin{Section}{XML structure}
The repository theme information is contained in an XML file written
by the repository maintainer (or \code{\LinkA{writeThemesXML}{writeThemesXML}}) called
\code{repThemes.xml}.  The XML structure for a set of repository
themes is defined as follows.

The \code{repositoryThemes} tag defines the primary XML block that is
specifying the themes for a particular repository.  Since every
\code{repThemes.xml} file corresponds to a particular repository,
there should only be one of these blocks per file, and it should
contain all other XML information.

Every individual theme is contained in a \code{theme} tag block.
Every theme for this particular repository needs to be defined as a
\code{theme} block.

Within every theme are four main subblocks: The \code{themeName} tag
block specifies the name of the theme, the \code{themeDesc} tag
provides for a description of this theme, the \code{themeRepos}
tag specifies the URL of the repository this theme belongs to and the
\code{themePackages} tag block specifies what packages are contained
within that theme. 

Inside of the \code{themePackages} tag block are a series of
\code{package} tag blocks, one for every package in the theme.

The \code{package} blocks contain one or two tags each.  Every
\code{package} block has a \code{packageName} tag block specifying the
name of the package, and there is an optional \code{packageVersion}
tag which allows the maintainer to specify a particular version of
that package.

An example of a three package theme is below.  Two of the packages
have versions specified, and one does not.
\begin{alltt}
    <?xml version="1.0"?>
    <repositoryThemes>
       <theme>
         <themeName>Testing</themeName>
         <themeDesc>This is a small test theme</themeDesc>
         <themeRepos>http://www.bioconductor.org/repository/</themeRepos>
         <themePackages>
           <package>
             <packageName>Biobase</packageName>
             <packageVersion>1.4.2</packageVersion>
           </package>
           <package>
             <packageName>ROC</packageName>
           </package>
           <package>
             <packageName>Ruuid</packageName>
             <packageVersion>1.3.3</packageVersion>
           </package>
         </themePackages>
      </theme>
    </repositoryThemes>
\end{alltt}
\end{Section}
\begin{Author}\relax
Jeff Gentry
\end{Author}
\begin{SeeAlso}\relax
\code{\LinkA{writeThemesXML}{writeThemesXML}}, \code{\LinkA{install.packages2}{install.packages2}},
\code{\LinkA{pkgInfo}{pkgInfo}}, \code{\LinkA{genRepos}{genRepos}}
\end{SeeAlso}
\begin{Examples}
\begin{ExampleCode}
   ## Need something here
\end{ExampleCode}
\end{Examples}