diff --git a/pyscript/configure.zcml b/pyscript/configure.zcml
index 97bebf0..1805f42 100644
--- a/pyscript/configure.zcml
+++ b/pyscript/configure.zcml
@@ -20,7 +20,7 @@
         />
     <require
         permission="zope.ManageContent"
-        set_attributes="source contentType"
+        set_attributes="parameters source contentType"
         />
     <implements
         interface="zope.annotation.interfaces.IAttributeAnnotatable"
diff --git a/pyscript/interfaces.py b/pyscript/interfaces.py
index 4efa110..12c8932 100644
--- a/pyscript/interfaces.py
+++ b/pyscript/interfaces.py
@@ -38,15 +38,21 @@ class IPythonScript(Interface):
     automatically.
     """
 
+    parameters = schema.TextLine(
+        title=_(u"Parameters"),
+        description=_(u"Space-separated list of parameter names."),
+        required=False,
+        default=u''
+    )
     source = schema.SourceText(
         title=_(u"Source"),
         description=_(u"The source of the Python page."),
         required=True,
     )
-
     contentType = schema.TextLine(
         title=_(u"Content Type"),
-        description=_(u"The content type the script outputs."),
+        description=_(u"The content type of the script's output (return value "
+                "when rendered in the browser)."),
         required=True,
         default=u"text/html",
     )
diff --git a/pyscript/plot.py b/pyscript/plot.py
index 24158d9..7794ab6 100644
--- a/pyscript/plot.py
+++ b/pyscript/plot.py
@@ -17,20 +17,46 @@
 #
 
 """
-View class(es) for images (plots).
+Management of filesystem images (plots) and corresponding views.
 
 $Id$
 """
 
 import os
+import time
 from zope.interface import Interface, implements
 from zope.cachedescriptors.property import Lazy
 
+from cybertools.util import randomname, jeep
+
+
+class CachedImage(object):
+    """ Keep information about temporary image files.
+    """
+
+    def __init__(self, path, name=None):
+        self.path = path
+        if name is None:
+            self.name = randomname.generateName(lambda x: x not in cachedImages)
+        else:
+            self.name = name
+        self.timeStamp = int(time.time())
+
+
+cachedImages = jeep.Jeep()
+
+def registerImage(filename, name=None):
+    image = CachedImage(filename, name)
+    cachedImages.append(image)
+    while len(cachedImages) > 10:  # clean up old cache entries
+        old = cachedImages.pop(0).path
+        if os.path.exists(old):
+            os.unlink(old)
+    return image.name
+
 
 class PlotView(object):
-    """ Abstract basic view class for Flash movies .
-
-        The assessment attribute has to be set by the subclass.
+    """ Access to temporary filesystem images.
     """
 
     def __init__(self, context, request):
@@ -44,10 +70,10 @@ class PlotView(object):
 
     def __call__(self):
         if self.traverse_subpath:
-            path = str('/' + os.path.join(*self.traverse_subpath))
+            key = self.traverse_subpath[0]
         else:
-            path = self.request.form.get('image')
-        # TODO: keep path in temporary dictionary with hashed keys.
+            key = self.request.form.get('image', 'not_found')
+        path = cachedImages[key].path
         self.setHeaders(path)
         f = open(path, 'rb')
         data = f.read()
diff --git a/pyscript/rstat.py b/pyscript/rstat.py
index 126b3c2..a5a2e42 100644
--- a/pyscript/rstat.py
+++ b/pyscript/rstat.py
@@ -26,6 +26,9 @@ import os
 import rpy
 from rpy import r
 from zope.proxy import removeAllProxies
+from zope.traversing.browser import absoluteURL
+
+from cybertools.pyscript.plot import registerImage
 
 
 class RWrapper(object):
@@ -49,8 +52,36 @@ with_mode = RWrapper(rpy.with_mode)
 #as_py = RWrapper(rpy.as_py)
 
 
-def graphics(*args, **kw):
-    filename = os.tempnam()
-    rc = r.GDD(filename, *args, **kw)
-    return filename + '.jpg', rc
+def gdd(**kw):
+    r.library('GDD')
+    filename = os.tempnam(None, 'rplot')
+    robj = r.GDD(filename, type='jpg', **kw)
+    return filename + '.jpg', robj
+
+def graphics(**kw):
+    context = kw.pop('context', None)
+    request = kw.pop('request', None)
+    fn, robj = gdd(**kw)
+    key = registerImage(fn)
+    return '%s/@@plot?image=%s' % (absoluteURL(context, request), key)
+
+
+class RStat(object):
+
+    def __init__(self, context, request):
+        self.context = context
+        self.request = request
+
+    def gdd(self, **kw):
+        r.library('GDD')
+        filename = os.tempnam(None, 'rplot')
+        robj = r.GDD(filename, type='jpg', **kw)
+        return filename + '.jpg', robj
+
+    def graphics(self, **kw):
+        request = self.request
+        context = self.context
+        fn, robj = gdd(**kw)
+        key = registerImage(fn)
+        return '%s/@@plot?image=%s' % (absoluteURL(context, request), key)
 
diff --git a/pyscript/script.py b/pyscript/script.py
index 83a4bba..1ff5188 100644
--- a/pyscript/script.py
+++ b/pyscript/script.py
@@ -89,11 +89,14 @@ class PythonScript(Contained, Persistent):
 
     _v_compiled = None
 
-    def __init__(self, source=u'', contentType=u'text/plain'):
+    parameters = u''
+
+    def __init__(self, source=u'', parameters=u'', contentType=u'text/plain'):
         """Initialize the object."""
         super(PythonScript, self).__init__()
         self.source = source
         self.contentType = contentType
+        self.parameters = parameters or u''
 
     def __filename(self):
         if self.__parent__ is None:
@@ -110,7 +113,8 @@ class PythonScript(Contained, Persistent):
         self.__source = source
         self.__prepared_source = self.prepareSource(source)
         # Compile objects cannot be pickled
-        self._v_compiled = Function(self.__prepared_source, self.__filename())
+        self._v_compiled = Function(self.__prepared_source,  self.parameters,
+                                    self.__filename())
 
     _tripleQuotedString = re.compile(
         r"^([ \t]*)[uU]?([rR]?)(('''|\"\"\")(.*)\4)", re.MULTILINE | re.DOTALL)
@@ -136,11 +140,11 @@ class PythonScript(Contained, Persistent):
 
     source = property(getSource, setSource)
 
-    def __call__(self, request, **kw):
+    def __call__(self, request, *args, **kw):
         output = StringIO()
         if self._v_compiled is None:
-            self._v_compiled = Function(self.__prepared_source,
-                                               self.__filename())
+            self._v_compiled = Function(self.__prepared_source, self.parameters,
+                                        self.__filename(),)
         parent = getParent(self)
         kw['request'] = request
         kw['script'] = self
@@ -149,7 +153,7 @@ class PythonScript(Contained, Persistent):
         kw['script_result'] = None
         if IScriptContainer.providedBy(parent):
             parent.updateGlobals(kw)
-        self._v_compiled(kw)
+        self._v_compiled(args, kw)
         result = kw['script_result']
         if result == output:
             result = result.getvalue().decode('unicode-escape')
@@ -160,8 +164,13 @@ class Function(object):
     """A compiled function.
     """
 
-    def __init__(self, source, filename='<string>'):
+    parameters = ''
+
+    def __init__(self, source, parameters='', filename='<string>'):
         lines = []
+        if parameters:
+            self.parameters = str(parameters).split()
+        #print '*** Function.parameters:', repr(self.parameters)
         lines.insert(0, 'def dummy(): \n    pass')
         for line in source.splitlines():
             lines.append('    ' + line)
@@ -170,8 +179,10 @@ class Function(object):
         #print '*** source:', source
         self.code = compile(source, filename, 'exec')
 
-    def __call__(self, globals):
+    def __call__(self, args, globals):
         globals['__builtins__'] = SafeBuiltins
+        for idx, p in enumerate(self.parameters):
+            globals[p] = args[idx]
         exec self.code in globals, None
 
 
@@ -192,7 +203,10 @@ class ScriptContainer(BTreeContainer):
     def updateGlobals(self, globs):
         if HAS_R:
             from cybertools.pyscript import rstat
-            globs['rstat'] = rstat
+            #globs['rstat'] = rstat
+            context = globs['context']
+            request = globs['request']
+            globs['rstat'] = rstat.RStat(context, request)
             globs['r'] = r
             globs['rpy'] = rpy