#
    # NOTE: Always return an empty string (i.e. and not any response data).
    #
    return ""
  }

  #
  # NOTE: This procedure returns a unique temporary directory where one or
  #       more files may be saved.  The prefix argument is a prefix for the
  #       directory name and it may be an empty string.  There is no attempt
  #       to actually create the resulting directory.
  #
  proc getUniqueTempDirectory { {prefix ""} } {
    variable temporaryRootDirectory

    set suffix [::PackageRepository::getUniqueSuffix]

    if {[string length $prefix] > 0} then {
      return [file join $temporaryRootDirectory \
          [appendArgs $prefix $suffix]]
    } else {
      return [file join $temporaryRootDirectory \
          $suffix]
    }
  }

  #
  # NOTE: This procedure checks if there is a higher version available of the
  #       specified package on the package file server.  The language argument
  #       must be one of the literal strings "eagle", "tcl", or "client".  The
  #       version argument must be one of the literal strings "8.4", "8.5", or
  #       "8.6" when the language is "tcl" -OR- the literal string "1.0" when
  #       the language is either "eagle" or "client".  The platform argument
  #       must be an empty string -OR- one of the literal strings "msil" or
  #       "neutral", or one of the values returned by the [getPlatform]
  #       procedure.  An empty string means that the associated package does
  #       not require a specific platform.  The packageName argument is a
  #       directory name relative to the language and version-specific
  #       directory on the package file server and may be an empty string.
  #       The usePgp argument should be non-zero when an OpenPGP signature
  #       file needs to be downloaded and verified for the downloaded file.
  #
  # <public>
  proc checkForHigherVersion { language version platform packageName usePgp } {
    variable clientDirectory
    variable persistentRootDirectory
    variable temporaryRootDirectory

    verifyLanguageAndVersion $language $version isClient
    verifyPlatform $platform platform

    set temporaryDirectory [file join \
    set temporaryDirectory [getUniqueTempDirectory pkgd_ver_]
        $temporaryRootDirectory [appendArgs \
        pkgd_ver_ [::PackageRepository::getUniqueSuffix]]]

    if {$isClient} then {
      set persistentDirectory $clientDirectory
    } else {
      verifyPersistentRootDirectory
      set persistentDirectory $persistentRootDirectory
    }

  #       needs to be verified for the downloaded file.
  #
  proc downloadAllPlatforms { language version packageName fileNames usePgp } {
    variable baseUri
    variable branchName
    variable platformsUri
    variable platformsUrn
    variable temporaryRootDirectory

    #
    # NOTE: Verify that the package language and version are correct.
    #
    verifyLanguageAndVersion $language $version isClient

    set temporaryDirectory [file join \
    set temporaryDirectory [getUniqueTempDirectory pkgd_plat_]
        $temporaryRootDirectory [appendArgs \
        pkgd_plat_ [::PackageRepository::getUniqueSuffix]]]

    set localFileName [file join $temporaryDirectory manifest.txt]
    file mkdir [file dirname $localFileName]

    #
    # NOTE: First, build the final URI to download from the remote package
    #       repository, performing any applicable substitutions in the URI

  #       -allowUpdate option should be non-zero to allow existing package
  #       files to be overwritten.
  #
  # <public>
  proc downloadFiles { language version platform fileNames options } {
    variable clientDirectory
    variable persistentRootDirectory
    variable temporaryRootDirectory
    variable viaInstall

    verifyLanguageAndVersion $language $version isClient
    verifyPlatform $platform platform

    set temporaryDirectory [file join \
    set temporaryDirectory [getUniqueTempDirectory pkgd_lib_]
        $temporaryRootDirectory [appendArgs \
        pkgd_lib_ [::PackageRepository::getUniqueSuffix]]]

    if {$isClient} then {
      set persistentDirectory $clientDirectory
    } else {
      verifyPersistentRootDirectory
      set persistentDirectory $persistentRootDirectory
    }