Shibboleth Developers

[Ian Young <>]

Tom Scavo wrote:

> You're idea is intriguing, Ian.

Here's my idea in concrete terms, as three patches against the current 
CVS head.

patch1.txt alters the IdP configuration file schema to allow any number 
of <Plugin> elements at the end.  Each one must have name (random string 
you can use to refer to the plugin in code) and implementation (class 
name) attributes, but can have any other attributes and any content 
model; it's up to the plugin to decode those.

patch2.txt is applied to the idp directory.  Most of the workings are in 
PluginCollection.java, which is mainly a knock-off of 
ProtocolHandlerFactory.java.  There is some bridging code in 
IdPProtocolSupport.java and some code to pick up the Plugin elements in 
IdPResponder.java.

A plugin class has to have a null constructor.  If it also implements 
the (pre-existing) PluggableConfigurationComponent interface, the 
instance is passed the <Plugin> element to configure itself with.

I've included an example plugin as TestPlugin.java, and there is a 
second hunk of changes in IdPResponder which demonstrates accessing a 
plugin from code.  Neither of these are really part of what would want 
to be checked in; they are just here as targets for discussion.

Finally, patch3.txt is applied to the idp.xml and shows what the 
configuration code looks like.

I've played around with this a bit, and I still quite like it.  If 
something along these lines were part of the base distribution, I could 
certainly implement my NAT stuff on top of it with minimal additional 
patching (when combined with Chad's new extension system).

Comments, anyone?

        -- Ian
Index: dist.idp.xml
===================================================================
RCS file: /home/cvs/shibboleth/shibboleth/java/src/conf/dist.idp.xml,v
retrieving revision 1.9
diff -u -r1.9 dist.idp.xml
--- dist.idp.xml        8 Jul 2005 21:03:17 -0000       1.9
+++ dist.idp.xml        9 Jul 2005 14:18:02 -0000
@@ -117,5 +117,12 @@
        <!--
        <MetadataProvider 
type="edu.internet2.middleware.shibboleth.metadata.provider.XMLMetadata"
                 uri="$SHIB_HOME$/etc/IQ-metadata.xml"/> -->
+    
+    <!-- example generic plugins -->
+       <Plugin name="my.plugin" 
implementation="edu.internet2.middleware.shibboleth.TestPlugin" foo="bar">
+               <SomeConfiguration>text</SomeConfiguration>
+       </Plugin>
+       <Plugin name="boring.plugin" implementation="java.util.Date"/>
+       
 </IdPConfig>
 
Index: shibboleth-idpconfig-1.0.xsd
===================================================================
RCS file: 
/home/cvs/shibboleth/shibboleth/java/src/schemas/shibboleth-idpconfig-1.0.xsd,v
retrieving revision 1.18
diff -u -r1.18 shibboleth-idpconfig-1.0.xsd
--- shibboleth-idpconfig-1.0.xsd        1 Jul 2005 21:12:39 -0000       1.18
+++ shibboleth-idpconfig-1.0.xsd        9 Jul 2005 14:17:21 -0000
@@ -130,6 +130,16 @@
                                                        <xs:anyAttribute 
namespace="##any" processContents="lax"/>
                                                </xs:complexType>
                                        </xs:element>
+                                       <xs:element name="Plugin" 
minOccurs="0" maxOccurs="unbounded">
+                                               <xs:complexType>
+                                                       <xs:sequence>
+                                                               <xs:any 
namespace="##any" processContents="lax" minOccurs="0" maxOccurs="unbounded"/>
+                                                       </xs:sequence>
+                                                       <xs:attribute 
name="implementation" type="xs:string" use="required" />
+                                                       <xs:attribute 
name="name" type="xs:string" use="required" />
+                                                       <xs:anyAttribute 
namespace="##any" processContents="lax"/>
+                                               </xs:complexType>
+                                       </xs:element>
                                </xs:sequence>
                                <xs:attribute name="resolverConfig" 
type="xs:string" use="optional" default="/conf/resolver.xml"/>
                                <xs:attribute name="AAUrl" type="xs:anyURI" 
use="optional"/>
Index: IdPProtocolSupport.java
===================================================================
RCS file: 
/home/cvs/shibboleth/shibboleth/java/src/edu/internet2/middleware/shibboleth/idp/IdPProtocolSupport.java,v
retrieving revision 1.16
diff -u -r1.16 IdPProtocolSupport.java
--- IdPProtocolSupport.java     20 Jun 2005 20:22:48 -0000      1.16
+++ IdPProtocolSupport.java     9 Jul 2005 14:34:34 -0000
@@ -71,6 +71,7 @@
        private ArtifactMapper artifactMapper;
        private Semaphore throttle;
        private Trust trust = new ShibbolethTrust();
+       private PluginCollection plugins = new PluginCollection();
 
        IdPProtocolSupport(IdPConfig config, Logger transactionLog, 
NameMapper nameMapper, ServiceProviderMapper spMapper,
                        ArpEngine arpEngine, AttributeResolver resolver, 
ArtifactMapper artifactMapper)
@@ -179,6 +180,15 @@
                }
        }
 
+       
+       public Object getPlugin(String name) {
+               return plugins.get(name);
+       }
+       
+       public void addPlugin(Element element) throws 
ShibbolethConfigurationException {
+               plugins.add(element);
+       }
+
        public int providerCount() {
 
                return metadata.size();
Index: IdPResponder.java
===================================================================
RCS file: 
/home/cvs/shibboleth/shibboleth/java/src/edu/internet2/middleware/shibboleth/idp/IdPResponder.java,v
retrieving revision 1.38
diff -u -r1.38 IdPResponder.java
--- IdPResponder.java   8 Jul 2005 17:41:58 -0000       1.38
+++ IdPResponder.java   9 Jul 2005 14:34:35 -0000
@@ -228,6 +228,13 @@
                                throw new 
ShibbolethConfigurationException("Could not load SAML metadata.");
                        }
 
+                       // Load generic plugins
+                       itemElements = 
idPConfig.getDocumentElement().getElementsByTagNameNS(IdPConfig.configNameSpace,
+                                       "Plugin");
+                       for (int i = 0; i < itemElements.getLength(); i++) {
+                               protocolSupport.addPlugin((Element) 
itemElements.item(i));
+                       }
+                       
                        log.info("Identity Provider initialization 
complete.");
 
                } catch (ShibbolethConfigurationException ae) {
@@ -252,6 +259,23 @@
                MDC.put("remoteAddr", request.getRemoteAddr());
                log.debug("Received a request via GET for location (" + 
request.getRequestURL() + ").");
 
+               /*
+                * Example code using plugins... not part of the 
implementation. 
+                */
+               Object plugged = protocolSupport.getPlugin("my.plugin");
+               if (plugged instanceof TestPlugin) {
+                       ((TestPlugin)plugged).sayHowdy();
+               }
+               plugged = protocolSupport.getPlugin("boring.plugin");
+               if (plugged != null)
+                       log.info("boring plugin says: " + plugged);
+               plugged = protocolSupport.getPlugin("missing.plugin");
+               if (plugged != null) {
+                       log.info("missing plugin says: " + plugged);
+               } else {
+                       log.info("missing plugin is missing");
+               }
+               
                try {
                        IdPProtocolHandler activeHandler = 
lookupProtocolHandler(request);
                        // Pass request to the appropriate handler
Index: PluginCollection.java
===================================================================
RCS file: PluginCollection.java
diff -N PluginCollection.java
--- /dev/null   1 Jan 1970 00:00:00 -0000
+++ PluginCollection.java       1 Jan 1970 00:00:00 -0000
@@ -0,0 +1,105 @@
+/*
+ * Copyright [2005] [University Corporation for Advanced Internet 
Development, Inc.]
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package edu.internet2.middleware.shibboleth.idp;
+
+import java.lang.reflect.Constructor;
+import java.lang.reflect.InvocationTargetException;
+import java.util.HashMap;
+import java.util.Map;
+
+import org.apache.log4j.Logger;
+import org.w3c.dom.Element;
+
+import 
edu.internet2.middleware.shibboleth.common.PluggableConfigurationComponent;
+import 
edu.internet2.middleware.shibboleth.common.ShibbolethConfigurationException;
+
+/**
+ * Collection class for loading generic plugin implementations based on XML 
configuration.
+ * 
+ * @author Ian Young, after Walter Hoehn
+ */
+public class PluginCollection {
+
+       private static Logger log = 
Logger.getLogger(PluginCollection.class.getName());
+       private Map/*<String, Object>*/ plugins = new HashMap();
+
+       public Object get(String name) {
+               return plugins.get(name);
+       }
+       
+       public void add(Element config) throws 
ShibbolethConfigurationException {
+               String name = config.getAttribute("name");
+               if (name == null || name.equals("")) {
+                       log.error("No plugin name specified.  Attribute 
(name) is "
+                                       + "required with element <Plugin/>.");
+                       throw new ShibbolethConfigurationException("Invalid 
configuration data supplied.");
+               }
+               
+               String implementation = config.getAttribute("implementation");
+               if (implementation == null || implementation.equals("")) {
+                       log.error("No plugin implementation specified.  
Attribute (implementation) is "
+                                       + "required with element <Plugin/>.");
+                       throw new ShibbolethConfigurationException("Invalid 
configuration data supplied.");
+
+               } else {
+
+                       log.info("Loading plugin \"" + name + "\" 
implementation=" + implementation);
+                       try {
+                               Class implClass = 
Class.forName(implementation);
+                               Constructor constructor = 
implClass.getConstructor(new Class[]{});
+                               Object rawImpl = constructor.newInstance(new 
Object[]{});
+
+                               /*
+                                * If the object is initializable, pass it 
the element.
+                                * If not, don't bother.
+                                */
+                               if (rawImpl instanceof 
PluggableConfigurationComponent) {
+                                       
((PluggableConfigurationComponent)rawImpl).initialize(config);
+                               }
+                               
+                               /*
+                                * Register this plugin.
+                                */
+                               plugins.put(name, rawImpl);
+
+                       } catch (ClassNotFoundException e) {
+                               log.error("Invalid configuration, supplied 
implementation class for the plugin "
+                                               + "could not be found: " + 
e.getMessage());
+                               throw new 
ShibbolethConfigurationException("Invalid configuration data supplied.");
+
+                       } catch (NoSuchMethodException e) {
+                               log.error("Invalid configuration, supplied 
implementation class for the plugin is "
+                                               + "not valid.  A DOM Element 
constructor is required: " + e.getMessage());
+                               throw new 
ShibbolethConfigurationException("Invalid configuration data supplied.");
+
+                       } catch (InvocationTargetException e) {
+                               Throwable cause = e.getCause();
+                               if (cause != null) {
+                                       log.error(cause.getMessage());
+                               }
+                               log.error("Invalid configuration, supplied 
implementation class for the plugin"
+                                               + " could not be loaded: " + 
e.getMessage());
+                               throw new 
ShibbolethConfigurationException("Invalid configuration data supplied.");
+                       } catch (Exception e) {
+                               log.error("Invalid configuration, supplied 
implementation class for the plugin"
+                                               + " could not be loaded: " + 
e.getMessage());
+                               throw new 
ShibbolethConfigurationException("Invalid configuration data supplied.");
+                       }
+               }
+       }
+
+}
Index: TestPlugin.java
===================================================================
RCS file: TestPlugin.java
diff -N TestPlugin.java
--- /dev/null   1 Jan 1970 00:00:00 -0000
+++ TestPlugin.java     1 Jan 1970 00:00:00 -0000
@@ -0,0 +1,22 @@
+package edu.internet2.middleware.shibboleth.idp;
+
+import org.apache.log4j.Logger;
+import org.w3c.dom.Element;
+
+import 
edu.internet2.middleware.shibboleth.common.PluggableConfigurationComponent;
+
+public class TestPlugin implements PluggableConfigurationComponent {
+
+       private static Logger log = 
Logger.getLogger(TestPlugin.class.getName());
+       private String foo = "(unset)";
+       
+       public void initialize(Element config) {
+               foo = config.getAttribute("foo");
+               if (foo == null || foo.equals("")) foo = "(missing)";
+               log.info("test plugin initialized, foo='" + foo + "'");
+       }
+
+       public void sayHowdy() {
+               log.info("plugin says howdy: '" + foo + "'");
+       }
+}