diff --git a/composer/README.txt b/composer/README.txt
new file mode 100644
index 0000000..541f5a6
--- /dev/null
+++ b/composer/README.txt
@@ -0,0 +1,78 @@
+================================================================
+Composer - Building Complex Structures with Templates or Schemas
+================================================================
+
+  ($Id$)
+
+  >>> from cybertools.composer.base import Element, Compound, Template
+  >>> from cybertools.composer.client import Instance, Client
+
+We set up a very simple demonstration system using a PC configurator.
+We start with two classes denoting a configuration and a simple
+component within this configuration.
+
+  >>> class Configuration(Template):
+  ...     def __init__(self, name):
+  ...         self.name = name
+  ...         super(Configuration, self).__init__()
+
+  >>> class BasicComponent(Element):
+  ...     def __init__(self, name):
+  ...         self.name = name
+  ...     def __repr__(self):
+  ...         return self.name
+
+  >>> desktop = Configuration('Desktop')
+  >>> desktop.components.append(BasicComponent('case'))
+  >>> desktop.components.append(BasicComponent('mainboard'))
+  >>> desktop.components.append(BasicComponent('cpu'))
+  >>> desktop.components.append(BasicComponent('harddisk'))
+
+Now somebody wants to configure a desktop PC using this configuration.
+We need another class denoting the product that will be created.
+
+  >>> class Product(object):
+  ...     def __init__(self, productId):
+  ...         self.productId = productId
+  ...         self.parts = {}
+  ...     def __repr__(self):
+  ...         return self.productId
+
+  >>> c001 = Product('c001')
+
+The real stuff will be done by an instance that connects the product
+(via the client) with the template.
+
+  >>> class ConfigurationInstance(Instance):
+  ...     def applyTemplate(self):
+  ...         for c in self.template.components:
+  ...             print c, self.parent.context.parts.get(c.name, '-')
+
+In this case we can directly use the basic client adapter for setting up the
+connection. As we have only one template we also associate only one
+instance with the client.
+
+  >>> client = Client(c001)
+  >>> client.instances.append(ConfigurationInstance(client, desktop))
+  >>> client.applyTemplates()
+  case -
+  mainboard -
+  cpu -
+  harddisk -
+
+If we have configured a CPU for our configuration this will be listed.
+
+  >>> c001.parts['cpu'] = Product('z80')
+  >>> client.applyTemplates()
+  case -
+  mainboard -
+  cpu z80
+  harddisk -
+
+Note that the ConfigurationInstance's applyTemplate() method is fairly
+primitive. In a real-world application there usually are a lot more methods
+that do more stuff. In our PC configurator application there might be
+methods that just list components (e.g. to provide a user interface),
+retrieve candidate products (e.g. CPUs) to use in the
+configuration and store the user's selection in the context object.
+
diff --git a/composer/__init__.py b/composer/__init__.py
new file mode 100644
index 0000000..4bc90fb
--- /dev/null
+++ b/composer/__init__.py
@@ -0,0 +1,4 @@
+"""
+$Id$
+"""
+
diff --git a/composer/base.py b/composer/base.py
new file mode 100644
index 0000000..0a0af1b
--- /dev/null
+++ b/composer/base.py
@@ -0,0 +1,55 @@
+#
+#  Copyright (c) 2007 Helmut Merz helmutm@cy55.de
+#
+#  This program is free software; you can redistribute it and/or modify
+#  it under the terms of the GNU General Public License as published by
+#  the Free Software Foundation; either version 2 of the License, or
+#  (at your option) any later version.
+#
+#  This program is distributed in the hope that it will be useful,
+#  but WITHOUT ANY WARRANTY; without even the implied warranty of
+#  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+#  GNU General Public License for more details.
+#
+#  You should have received a copy of the GNU General Public License
+#  along with this program; if not, write to the Free Software
+#  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+#
+
+"""
+Basic classes for a complex template structures.
+
+$Id$
+"""
+
+from zope.interface import implements
+
+from cybertools.composer.interfaces import IComponent, IElement, ICompound
+from cybertools.composer.interfaces import ITemplate
+
+
+class Component(object):
+
+    implements(IComponent)
+
+
+class Element(Component):
+
+    implements(IElement)
+
+
+class Compound(Component):
+
+    implements(ICompound)
+
+    def __init__(self):
+        self.parts = []
+
+
+class Template(object):
+
+    implements(ITemplate)
+
+    def __init__(self):
+        self.components = []
+
diff --git a/composer/client.py b/composer/client.py
new file mode 100644
index 0000000..c4a6041
--- /dev/null
+++ b/composer/client.py
@@ -0,0 +1,56 @@
+#
+#  Copyright (c) 2007 Helmut Merz helmutm@cy55.de
+#
+#  This program is free software; you can redistribute it and/or modify
+#  it under the terms of the GNU General Public License as published by
+#  the Free Software Foundation; either version 2 of the License, or
+#  (at your option) any later version.
+#
+#  This program is distributed in the hope that it will be useful,
+#  but WITHOUT ANY WARRANTY; without even the implied warranty of
+#  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+#  GNU General Public License for more details.
+#
+#  You should have received a copy of the GNU General Public License
+#  along with this program; if not, write to the Free Software
+#  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+#
+
+"""
+Base classes to be used for client adapters.
+
+$Id$
+"""
+
+from zope.interface import implements
+
+from cybertools.composer.interfaces import IInstance, IClient
+
+
+class Instance(object):
+
+    implements(IInstance)
+
+    parent = None
+    template = None
+
+    def __init__(self, parent, template):
+        self.parent = parent
+        self.template = template
+
+    def applyTemplate(self, *args, **kw):
+        raise ValueError('To be implemented by subclass')
+
+
+class Client(object):
+
+    implements(IClient)
+
+    def __init__(self, context):
+        self.context = context
+        self.instances = []
+
+    def applyTemplates(self, *args, **kw):
+        for inst in self.instances:
+            inst.applyTemplate(*args, **kw)
+
diff --git a/composer/interfaces.py b/composer/interfaces.py
new file mode 100644
index 0000000..f80233a
--- /dev/null
+++ b/composer/interfaces.py
@@ -0,0 +1,86 @@
+#
+#  Copyright (c) 2007 Helmut Merz helmutm@cy55.de
+#
+#  This program is free software; you can redistribute it and/or modify
+#  it under the terms of the GNU General Public License as published by
+#  the Free Software Foundation; either version 2 of the License, or
+#  (at your option) any later version.
+#
+#  This program is distributed in the hope that it will be useful,
+#  but WITHOUT ANY WARRANTY; without even the implied warranty of
+#  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+#  GNU General Public License for more details.
+#
+#  You should have received a copy of the GNU General Public License
+#  along with this program; if not, write to the Free Software
+#  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+#
+
+"""
+Complex structures with templates/schemas.
+
+$Id$
+"""
+
+from zope.interface import Interface, Attribute
+
+
+# template side interfaces
+
+class IComponent(Interface):
+    """ Basic building block. A component may be part of other components.
+    """
+
+
+class IElement(IComponent):
+    """ A final or elementary component, i.e. one that does not consist
+        of other components.
+    """
+
+
+class ICompound(IComponent):
+    """ A component that consists of other components.
+    """
+
+    parts = Attribute('An ordered sequence of the components this '
+                      'object consists of')
+
+
+class ITemplate(Interface):
+    """ A structure, consisting of components, that may be used as a
+        template/schema/blueprint for client objects.
+    """
+
+    components = Attribute('An ordered sequence of the components this '
+                      'object is built upon')
+
+
+# client side interfaces
+
+class IInstance(Interface):
+    """ Represents an object that uses a template.
+    """
+
+    parent = Attribute('The client this instance belongs to')
+    template = Attribute('Template this instance is associated with')
+
+    def applyTemplate(*args, **kw):
+        """ Apply the template (in the parent's context). Note that this
+            method is just an example - instance classes may define
+            other methods that provide more specific actions.
+        """
+
+
+class IClient(Interface):
+    """ Represents an object that uses a set of templates via its instances.
+    """
+
+    context = Attribute('Object this client adapter has been created for')
+    instances = Attribute('An ordered or unordered sequence of instance objects')
+
+    def applyTemplates(*args, **kw):
+        """ Apply the templates of all instances. Note that this
+            method is just an example - client classes may define
+            other methods that provide more specific actions.
+        """
+
diff --git a/composer/schema/__init__.py b/composer/schema/__init__.py
new file mode 100644
index 0000000..4bc90fb
--- /dev/null
+++ b/composer/schema/__init__.py
@@ -0,0 +1,4 @@
+"""
+$Id$
+"""
+
diff --git a/composer/tests.py b/composer/tests.py
new file mode 100755
index 0000000..ccfbd9a
--- /dev/null
+++ b/composer/tests.py
@@ -0,0 +1,22 @@
+# $Id$
+
+import unittest, doctest
+from zope.testing.doctestunit import DocFileSuite
+
+
+class Test(unittest.TestCase):
+    "Basic tests for the cybertools.composer package."
+
+    def testBasics(self):
+        pass
+
+
+def test_suite():
+    flags = doctest.NORMALIZE_WHITESPACE | doctest.ELLIPSIS
+    return unittest.TestSuite((
+                unittest.makeSuite(Test),
+                DocFileSuite('README.txt', optionflags=flags),
+            ))
+
+if __name__ == '__main__':
+    unittest.main(defaultTest='test_suite')
diff --git a/organize/README.txt b/organize/README.txt
index 5b64ed5..dca6b51 100644
--- a/organize/README.txt
+++ b/organize/README.txt
@@ -51,4 +51,4 @@ Let's create an address and assign it to a person:
 Service Management
 ==================
 
-  >>> from cybertools.organize.service import ServiceInstance
+  >>> from cybertools.organize.service import Service
diff --git a/organize/interfaces.py b/organize/interfaces.py
index a13533c..6bc6d99 100644
--- a/organize/interfaces.py
+++ b/organize/interfaces.py
@@ -122,30 +122,29 @@ class ITask(Interface):
 
 # services
 
-
-class IService(Interface):
-    """ A general service definition or a group of service instances,
+class IServiceGroup(Interface):
+    """ A group of related services or a general service definition,
         e.g. a regular bus service or a series of trainings.
     """
 
 
-class IServiceInstance(Interface):
-    """ A concrete service instance that clients may register with.
+class IService(Interface):
+    """ A service that clients may register with.
     """
 
-    service = Attribute('The service this object is an instance of.')
+    serviceGroup = Attribute('The service group this object is an instance of.')
 
-    seats = schema.Int(
-                    title=_(u'Number of Seats'),
+    capacity = schema.Int(
+                    title=_(u'Capacity'),
                     description=_(u'The capacity (maximum number of clients) '
                         'of this service; a negative number means: '
                         'no restriction, i.e. unlimited capacity.'),
                     required=False,)
 
-    availableSeats = Attribute('Available capacity, i.e. number of seats '
+    availableCapacity = Attribute('Available capacity, i.e. number of seats '
                         'still available; a negative number means: '
-                        'no restriction, i.e. unlimited capacity. '
-                        'Read-only attribute')
+                        'no restriction, i.e. unlimited capacity; '
+                        'read-only')
 
     serviceProviders = Attribute('A collection of one or more service providers.')
 
@@ -156,12 +155,12 @@ class IServiceInstance(Interface):
     def register(client):
         """ Register a client with this service. Return an IRegistration
             object if the registration is successful, otherwise
-            (e.g. if no seat is available) return None.
+            (e.g. if the service's capacity is exhausted) return None.
         """
 
 
-class IScheduledServiceInstance(IServiceInstance):
-    """ A service instance that starts at a certain date/time and
+class IScheduledService(IService):
+    """ A service that starts at a certain date/time and
         usually ends a certain time later.
     """
 
@@ -187,13 +186,12 @@ class IRegistration(Interface):
 class IResource(Interface):
     """ A resource is needed by a service to be able to work, e.g. a
         room or a bus. A resource may have a limited capacity so that
-        at a certain time it may only be used by services to certain
+        at a certain time it may only be used by services to a certain
         extent.
     """
 
 
 class IServiceProvider(Interface):
-    """ An entity, e.g. a person or an institution, that is responsible
-        for providing a service or a service instance.
+    """ A party, that is responsible for providing a service.
     """
 
diff --git a/organize/service.py b/organize/service.py
new file mode 100644
index 0000000..7bafba7
--- /dev/null
+++ b/organize/service.py
@@ -0,0 +1,62 @@
+#
+#  Copyright (c) 2007 Helmut Merz helmutm@cy55.de
+#
+#  This program is free software; you can redistribute it and/or modify
+#  it under the terms of the GNU General Public License as published by
+#  the Free Software Foundation; either version 2 of the License, or
+#  (at your option) any later version.
+#
+#  This program is distributed in the hope that it will be useful,
+#  but WITHOUT ANY WARRANTY; without even the implied warranty of
+#  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+#  GNU General Public License for more details.
+#
+#  You should have received a copy of the GNU General Public License
+#  along with this program; if not, write to the Free Software
+#  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+#
+
+"""
+Service instance classes.
+
+$Id$
+"""
+
+from zope.interface import implements
+
+from cybertools.organize.interfaces import IService
+from cybertools.organize.interfaces import IScheduledService
+
+
+class Registration(object):
+
+    def __init__(self, client):
+        self.client = client
+
+
+class Service(object):
+
+    implements(IService)
+
+    def __init__(self, seats=-1):
+        self.capacity = capacity
+        self.registrations = []
+
+    @property
+    def availableCapacity(self):
+        if self.capacity >= 0 and len(self.registrations) >= self.capacity:
+            return 0
+        return self.capacity - len(self.registrations)
+
+    def register(self, client):
+        if self.availableCapacity:
+            reg = Registration(client)
+            self.registrations.append(reg)
+            return reg
+        return None
+
+
+class ScheduledService(Service):
+
+    implements(IScheduledService)
+