\name{parseGmModel}
\alias{parseGmModel}
\alias{xmlHypergraph}
\title{Reads/writes a graphical model from the StatShop XML.}
\description{
  The function \code{parseGmModel} reads a StatShop \code{gm.xml} file
  and creates a \code{gmModel} object from it.

  The function \code{xmlHypergraph} creates an \code{XMLNode}
  representing the model.
}
\usage{
parseGmModel(filename, type)
xmlHypergraph(model, toplevel = TRUE)
}
\arguments{
  \item{filename}{Filename for \code{gm.xml} file.}
  \item{type}{Optional argument giving the type, should be one of "SM"
    or "EM/LM".  If missing, will try and discover the type based on the
    presence or absence of a \code{<TaskID>} element.}
  \item{model}{An object of type \code{gmModel}}
  \item{toplevel}{A logical flag, if true the appropriate XML namespace
    and schema attributes are added to the top level node.}
}
\value{
  For \sQuote{parseGmModel}, a \code{gmModel} object containig all of
  the variables and distributions in the \code{gm.xml} file.

  For \sQuote{xmlHypergraph} an \code{XMLNode} object containing the 
  information for \code{model}.
}
\details{
  The function \code{parseAMD} calls \code{parseGmModel} to the details
  for Student, Evidence and Link Models.  The \code{type} argument is
  passed to indicate what type of model is expected.  Usually the system
  can distinguish between Student and Evidence Models on the presense of
  \code{<StudentModelID>} vs \code{<LinkID>} tags in the XML.  However,
  it can't currently distinguish between Evidence and Link Models
  without help.

  The function \code{xmlHypergraph} produces the XML code for the master 
  file.  It produces an object of type \code{XMLNode} (which
  \code{writeAMD} writes to \code{amdfile}).  As this is the top level
  XML object, the constant \code{amdf.prefix} gives the namespace prefix
  and the constants \code{amdf.namespace} and \code{amdf.schemaLocation}
  provide details about the schema location.
}
\references{
  \url{http://research.ets.org/~ralmond/StatShop/dataFormats.html}
}
\author{Russell Almond}
\seealso{\code{\link{gmModel}},\code{\link{getGmModelFromNode}},
    \code{\link[XML]{XMLNode}}, \code{\link{gm.namespace}},
  \code{\link{gm.prefix}}, \code{\link{gm.schemaLocation}},
  \code{\link{xmlWrite}}, \code{\link{parseAMD}},
}
\examples{
# Assumes StatShop is installed on the test machine.
StatShop <- Sys.getenv("STATSHOP")
if (StatShop == "") {
  warn("StatShop not installed, skipping test.")
} else {

E5 <- parseGmModel(paste(StatShop,"TestScripts","ICT","Version0",
           "Hybrid","FixedContext","P4_EvaluateS5_EM.gm.xml",
            sep=.Platform$file.sep))
## Write out the result
## Need a writeable directory.
outdir <- ifelse(.Platform$OS.type == "windows", "C:/temp","/tmp")
xmlWrite(xmlHypergraph(E5),paste(outdir,"E5testout.gm.xml",
                           sep=.Platform$file.sep))

}
}
\keyword{interface}