adding constaints to intent API
diff --git a/core/net/src/main/java/org/onlab/onos/net/intent/impl/ConnectivityIntentCompiler.java b/core/net/src/main/java/org/onlab/onos/net/intent/impl/ConnectivityIntentCompiler.java
new file mode 100644
index 0000000..cecff78
--- /dev/null
+++ b/core/net/src/main/java/org/onlab/onos/net/intent/impl/ConnectivityIntentCompiler.java
@@ -0,0 +1,136 @@
+/*
+ * Copyright 2014 Open Networking Laboratory
+ *
+ * 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 org.onlab.onos.net.intent.impl;
+
+import org.apache.felix.scr.annotations.Component;
+import org.apache.felix.scr.annotations.Reference;
+import org.apache.felix.scr.annotations.ReferenceCardinality;
+import org.onlab.onos.net.ElementId;
+import org.onlab.onos.net.Path;
+import org.onlab.onos.net.intent.ConnectivityIntent;
+import org.onlab.onos.net.intent.Constraint;
+import org.onlab.onos.net.intent.IntentCompiler;
+import org.onlab.onos.net.intent.IntentExtensionService;
+import org.onlab.onos.net.provider.ProviderId;
+import org.onlab.onos.net.resource.LinkResourceService;
+import org.onlab.onos.net.topology.LinkWeight;
+import org.onlab.onos.net.topology.PathService;
+import org.onlab.onos.net.topology.TopologyEdge;
+
+import java.util.Iterator;
+import java.util.List;
+import java.util.Set;
+
+/**
+ * Base class for compilers of various
+ * {@link org.onlab.onos.net.intent.ConnectivityIntent connectivity intents}.
+ */
+@Component(immediate = true)
+public abstract class ConnectivityIntentCompiler<T extends ConnectivityIntent>
+        implements IntentCompiler<T> {
+
+    private static final ProviderId PID = new ProviderId("core", "org.onlab.onos.core", true);
+
+    @Reference(cardinality = ReferenceCardinality.MANDATORY_UNARY)
+    protected IntentExtensionService intentManager;
+
+    @Reference(cardinality = ReferenceCardinality.MANDATORY_UNARY)
+    protected PathService pathService;
+
+    @Reference(cardinality = ReferenceCardinality.MANDATORY_UNARY)
+    protected LinkResourceService resourceService;
+
+    /**
+     * Returns an edge-weight capable of evaluating links on the basis of the
+     * specified constraints.
+     *
+     * @param constraints path constraints
+     * @return edge-weight function
+     */
+    protected LinkWeight weight(List<Constraint> constraints) {
+        return new ConstraintBasedLinkWeight(constraints);
+    }
+
+    /**
+     * Validates the specified path against the given constraints.
+     *
+     * @param path path to be checked
+     * @return true if the path passes all constraints
+     */
+    protected boolean checkPath(Path path, List<Constraint> constraints) {
+        for (Constraint constraint : constraints) {
+            if (!constraint.validate(path, resourceService)) {
+                return false;
+            }
+        }
+        return true;
+    }
+
+    /**
+     * Computes a path between two ConnectPoints.
+     *
+     * @param one start of the path
+     * @param two end of the path
+     * @return Path between the two
+     * @throws PathNotFoundException if a path cannot be found
+     */
+    protected Path getPath(ConnectivityIntent intent,
+                           ElementId one, ElementId two) {
+        Set<Path> paths = pathService.getPaths(one, two, weight(intent.constraints()));
+        if (paths.isEmpty()) {
+            throw new PathNotFoundException("No packet path from " + one + " to " + two);
+        }
+        // TODO: let's be more intelligent about this eventually
+        return paths.iterator().next();
+    }
+
+    /**
+     * Edge-weight capable of evaluating link cost using a set of constraints.
+     */
+    protected class ConstraintBasedLinkWeight implements LinkWeight {
+
+        private final List<Constraint> constraints;
+
+        /**
+         * Creates a new edge-weight function capable of evaluating links
+         * on the basis of the specified constraints.
+         *
+         * @param constraints path constraints
+         */
+        ConstraintBasedLinkWeight(List<Constraint> constraints) {
+            this.constraints = constraints;
+        }
+
+        @Override
+        public double weight(TopologyEdge edge) {
+            if (constraints == null) {
+                return 1.0;
+            }
+
+            // iterate over all constraints in order and return the weight of
+            // the first one with fast fail over the first failure
+            Iterator<Constraint> it = constraints.iterator();
+            double cost = it.next().cost(edge.link(), resourceService);
+            while (it.hasNext() && cost > 0) {
+                if (it.next().cost(edge.link(), resourceService) < 0) {
+                    return -1;
+                }
+            }
+            return cost;
+        }
+    }
+
+}
diff --git a/core/net/src/main/java/org/onlab/onos/net/intent/impl/HostToHostIntentCompiler.java b/core/net/src/main/java/org/onlab/onos/net/intent/impl/HostToHostIntentCompiler.java
index 37cf84b..605d3c7 100644
--- a/core/net/src/main/java/org/onlab/onos/net/intent/impl/HostToHostIntentCompiler.java
+++ b/core/net/src/main/java/org/onlab/onos/net/intent/impl/HostToHostIntentCompiler.java
@@ -15,30 +15,21 @@
  */
 package org.onlab.onos.net.intent.impl;
 
-import java.util.Arrays;
-import java.util.List;
-import java.util.Set;
-
 import org.apache.felix.scr.annotations.Activate;
 import org.apache.felix.scr.annotations.Component;
 import org.apache.felix.scr.annotations.Deactivate;
 import org.apache.felix.scr.annotations.Reference;
 import org.apache.felix.scr.annotations.ReferenceCardinality;
 import org.onlab.onos.net.Host;
-import org.onlab.onos.net.HostId;
-import org.onlab.onos.net.Link;
 import org.onlab.onos.net.Path;
 import org.onlab.onos.net.flow.TrafficSelector;
 import org.onlab.onos.net.host.HostService;
 import org.onlab.onos.net.intent.HostToHostIntent;
 import org.onlab.onos.net.intent.Intent;
-import org.onlab.onos.net.intent.IntentCompiler;
-import org.onlab.onos.net.intent.IntentExtensionService;
 import org.onlab.onos.net.intent.PathIntent;
-import org.onlab.onos.net.topology.LinkWeight;
-import org.onlab.onos.net.resource.LinkResourceRequest;
-import org.onlab.onos.net.topology.PathService;
-import org.onlab.onos.net.topology.TopologyEdge;
+
+import java.util.Arrays;
+import java.util.List;
 
 import static org.onlab.onos.net.flow.DefaultTrafficSelector.builder;
 
@@ -47,13 +38,7 @@
  */
 @Component(immediate = true)
 public class HostToHostIntentCompiler
-        implements IntentCompiler<HostToHostIntent> {
-
-    @Reference(cardinality = ReferenceCardinality.MANDATORY_UNARY)
-    protected IntentExtensionService intentManager;
-
-    @Reference(cardinality = ReferenceCardinality.MANDATORY_UNARY)
-    protected PathService pathService;
+        extends ConnectivityIntentCompiler<HostToHostIntent> {
 
     @Reference(cardinality = ReferenceCardinality.MANDATORY_UNARY)
     protected HostService hostService;
@@ -70,8 +55,8 @@
 
     @Override
     public List<Intent> compile(HostToHostIntent intent) {
-        Path pathOne = getPath(intent.one(), intent.two());
-        Path pathTwo = getPath(intent.two(), intent.one());
+        Path pathOne = getPath(intent, intent.one(), intent.two());
+        Path pathTwo = getPath(intent, intent.two(), intent.one());
 
         Host one = hostService.getHost(intent.one());
         Host two = hostService.getHost(intent.two());
@@ -85,22 +70,7 @@
                                     HostToHostIntent intent) {
         TrafficSelector selector = builder(intent.selector())
                 .matchEthSrc(src.mac()).matchEthDst(dst.mac()).build();
-        return new PathIntent(intent.appId(), selector, intent.treatment(),
-                              path, new LinkResourceRequest[0]);
+        return new PathIntent(intent.appId(), selector, intent.treatment(), path);
     }
 
-    private Path getPath(HostId one, HostId two) {
-        Set<Path> paths = pathService.getPaths(one, two, new LinkWeight() {
-            @Override
-            public double weight(TopologyEdge edge) {
-                return edge.link().type() == Link.Type.OPTICAL ? -1 : +1;
-            }
-        });
-
-        if (paths.isEmpty()) {
-            throw new PathNotFoundException("No path from host " + one + " to " + two);
-        }
-        // TODO: let's be more intelligent about this eventually
-        return paths.iterator().next();
-    }
 }
diff --git a/core/net/src/main/java/org/onlab/onos/net/intent/impl/PathIntentInstaller.java b/core/net/src/main/java/org/onlab/onos/net/intent/impl/PathIntentInstaller.java
index c3b27bf..461f670 100644
--- a/core/net/src/main/java/org/onlab/onos/net/intent/impl/PathIntentInstaller.java
+++ b/core/net/src/main/java/org/onlab/onos/net/intent/impl/PathIntentInstaller.java
@@ -35,10 +35,13 @@
 import org.onlab.onos.net.flow.FlowRuleBatchOperation;
 import org.onlab.onos.net.flow.TrafficSelector;
 import org.onlab.onos.net.flow.TrafficTreatment;
+import org.onlab.onos.net.intent.Constraint;
 import org.onlab.onos.net.intent.IntentExtensionService;
 import org.onlab.onos.net.intent.IntentInstaller;
 import org.onlab.onos.net.intent.PathIntent;
+import org.onlab.onos.net.resource.DefaultLinkResourceRequest;
 import org.onlab.onos.net.resource.LinkResourceAllocations;
+import org.onlab.onos.net.resource.LinkResourceRequest;
 import org.onlab.onos.net.resource.LinkResourceService;
 import org.slf4j.Logger;
 
@@ -79,13 +82,7 @@
 
     @Override
     public List<FlowRuleBatchOperation> install(PathIntent intent) {
-        if (intent.resourceRequests().length > 0) {
-            LinkResourceAllocations allocations = allocateBandwidth(intent);
-            if (allocations == null) {
-                log.debug("Insufficient bandwidth available to install path intent {}", intent);
-                return null;
-            }
-        }
+        LinkResourceAllocations allocations = allocateResources(intent);
 
         TrafficSelector.Builder builder =
                 DefaultTrafficSelector.builder(intent.selector());
@@ -110,6 +107,10 @@
 
     @Override
     public List<FlowRuleBatchOperation> uninstall(PathIntent intent) {
+        LinkResourceAllocations allocatedResources = resourceService.getAllocations(intent.id());
+        if (allocatedResources != null) {
+            resourceService.releaseResources(allocatedResources);
+        }
         TrafficSelector.Builder builder =
                 DefaultTrafficSelector.builder(intent.selector());
         Iterator<Link> links = intent.path().links().iterator();
@@ -130,8 +131,23 @@
         return Lists.newArrayList(new FlowRuleBatchOperation(rules));
     }
 
-    private LinkResourceAllocations allocateBandwidth(PathIntent intent) {
-        return resourceService.requestResources(intent.resourceRequests()[0]);
+    /**
+     * Allocate resources required for an intent.
+     *
+     * @param intent intent to allocate resource for
+     * @return allocated resources if any are required, null otherwise
+     */
+    private LinkResourceAllocations allocateResources(PathIntent intent) {
+        if (intent.constraints() == null) {
+            return null;
+        }
+        LinkResourceRequest.Builder builder =
+                DefaultLinkResourceRequest.builder(intent.id(), intent.path().links());
+        for (Constraint constraint : intent.constraints()) {
+            builder.addConstraint(constraint);
+        }
+        LinkResourceRequest request = builder.build();
+        return request.resources().isEmpty() ? null : resourceService.requestResources(request);
     }
 
     // TODO refactor below this line... ----------------------------
diff --git a/core/net/src/main/java/org/onlab/onos/net/intent/impl/PointToPointIntentCompiler.java b/core/net/src/main/java/org/onlab/onos/net/intent/impl/PointToPointIntentCompiler.java
index 893b7ea..c32c8ee 100644
--- a/core/net/src/main/java/org/onlab/onos/net/intent/impl/PointToPointIntentCompiler.java
+++ b/core/net/src/main/java/org/onlab/onos/net/intent/impl/PointToPointIntentCompiler.java
@@ -15,31 +15,20 @@
  */
 package org.onlab.onos.net.intent.impl;
 
-import java.util.ArrayList;
-import java.util.List;
-import java.util.Set;
-
 import org.apache.felix.scr.annotations.Activate;
 import org.apache.felix.scr.annotations.Component;
 import org.apache.felix.scr.annotations.Deactivate;
-import org.apache.felix.scr.annotations.Reference;
-import org.apache.felix.scr.annotations.ReferenceCardinality;
-import org.onlab.onos.net.ConnectPoint;
 import org.onlab.onos.net.DefaultEdgeLink;
 import org.onlab.onos.net.DefaultPath;
 import org.onlab.onos.net.Link;
 import org.onlab.onos.net.Path;
 import org.onlab.onos.net.intent.Intent;
-import org.onlab.onos.net.intent.IntentCompiler;
-import org.onlab.onos.net.intent.IntentExtensionService;
 import org.onlab.onos.net.intent.PathIntent;
 import org.onlab.onos.net.intent.PointToPointIntent;
 import org.onlab.onos.net.provider.ProviderId;
-import org.onlab.onos.net.resource.LinkResourceRequest;
-import org.onlab.onos.net.topology.LinkWeight;
-import org.onlab.onos.net.topology.Topology;
-import org.onlab.onos.net.topology.TopologyEdge;
-import org.onlab.onos.net.topology.TopologyService;
+
+import java.util.ArrayList;
+import java.util.List;
 
 import static java.util.Arrays.asList;
 
@@ -48,14 +37,11 @@
  */
 @Component(immediate = true)
 public class PointToPointIntentCompiler
-        implements IntentCompiler<PointToPointIntent> {
+        extends ConnectivityIntentCompiler<PointToPointIntent> {
 
-    private static final ProviderId PID = new ProviderId("core", "org.onlab.onos.core", true);
-    @Reference(cardinality = ReferenceCardinality.MANDATORY_UNARY)
-    protected IntentExtensionService intentManager;
-
-    @Reference(cardinality = ReferenceCardinality.MANDATORY_UNARY)
-    protected TopologyService topologyService;
+    // TODO: use off-the-shell core provider ID
+    private static final ProviderId PID =
+            new ProviderId("core", "org.onlab.onos.core", true);
 
     @Activate
     public void activate() {
@@ -69,15 +55,16 @@
 
     @Override
     public List<Intent> compile(PointToPointIntent intent) {
-        Path path = getPath(intent.ingressPoint(), intent.egressPoint());
+        Path path = getPath(intent, intent.ingressPoint().deviceId(),
+                            intent.egressPoint().deviceId());
 
         List<Link> links = new ArrayList<>();
         links.add(DefaultEdgeLink.createEdgeLink(intent.ingressPoint(), true));
         links.addAll(path.links());
         links.add(DefaultEdgeLink.createEdgeLink(intent.egressPoint(), false));
 
-        return asList(createPathIntent(new DefaultPath(PID, links, path.cost() + 2,
-                path.annotations()), intent));
+        return asList(createPathIntent(new DefaultPath(PID, links, path.cost(),
+                                                       path.annotations()), intent));
     }
 
     /**
@@ -90,34 +77,7 @@
     private Intent createPathIntent(Path path,
                                     PointToPointIntent intent) {
         return new PathIntent(intent.appId(),
-                              intent.selector(), intent.treatment(), path,
-                              new LinkResourceRequest[0]);
+                              intent.selector(), intent.treatment(), path);
     }
 
-    /**
-     * Computes a path between two ConnectPoints.
-     *
-     * @param one start of the path
-     * @param two end of the path
-     * @return Path between the two
-     * @throws PathNotFoundException if a path cannot be found
-     */
-    private Path getPath(ConnectPoint one, ConnectPoint two) {
-        Topology topology = topologyService.currentTopology();
-        LinkWeight weight = new LinkWeight() {
-            @Override
-            public double weight(TopologyEdge edge) {
-                return edge.link().type() == Link.Type.OPTICAL ? -1 : +1;
-            }
-        };
-
-        Set<Path> paths = topologyService.getPaths(topology, one.deviceId(),
-                                                   two.deviceId(), weight);
-        if (paths.isEmpty()) {
-            throw new PathNotFoundException("No packet path from " + one + " to " + two);
-        }
-
-        // TODO: let's be more intelligent about this eventually
-        return paths.iterator().next();
-    }
 }
diff --git a/core/net/src/main/java/org/onlab/onos/net/intent/impl/PointToPointIntentWithBandwidthConstraintCompiler.java b/core/net/src/main/java/org/onlab/onos/net/intent/impl/PointToPointIntentWithBandwidthConstraintCompiler.java
deleted file mode 100644
index a192a9f..0000000
--- a/core/net/src/main/java/org/onlab/onos/net/intent/impl/PointToPointIntentWithBandwidthConstraintCompiler.java
+++ /dev/null
@@ -1,146 +0,0 @@
-package org.onlab.onos.net.intent.impl;
-
-import java.util.ArrayList;
-import java.util.Arrays;
-import java.util.List;
-import java.util.Set;
-
-import org.apache.felix.scr.annotations.Activate;
-import org.apache.felix.scr.annotations.Component;
-import org.apache.felix.scr.annotations.Deactivate;
-import org.apache.felix.scr.annotations.Reference;
-import org.apache.felix.scr.annotations.ReferenceCardinality;
-import org.onlab.onos.net.ConnectPoint;
-import org.onlab.onos.net.DefaultEdgeLink;
-import org.onlab.onos.net.DefaultPath;
-import org.onlab.onos.net.Link;
-import org.onlab.onos.net.Path;
-import org.onlab.onos.net.intent.Intent;
-import org.onlab.onos.net.intent.IntentCompiler;
-import org.onlab.onos.net.intent.IntentExtensionService;
-import org.onlab.onos.net.intent.PathIntent;
-import org.onlab.onos.net.intent.PointToPointIntent;
-import org.onlab.onos.net.intent.PointToPointIntentWithBandwidthConstraint;
-import org.onlab.onos.net.provider.ProviderId;
-import org.onlab.onos.net.resource.BandwidthResourceRequest;
-import org.onlab.onos.net.resource.DefaultLinkResourceRequest;
-import org.onlab.onos.net.resource.LinkResourceRequest;
-import org.onlab.onos.net.resource.LinkResourceService;
-import org.onlab.onos.net.resource.ResourceRequest;
-import org.onlab.onos.net.resource.ResourceType;
-import org.onlab.onos.net.topology.LinkWeight;
-import org.onlab.onos.net.topology.Topology;
-import org.onlab.onos.net.topology.TopologyEdge;
-import org.onlab.onos.net.topology.TopologyService;
-
-/**
- * A intent compiler for {@link org.onlab.onos.net.intent.HostToHostIntent}.
- */
-@Component(immediate = true)
-public class PointToPointIntentWithBandwidthConstraintCompiler
-        implements IntentCompiler<PointToPointIntentWithBandwidthConstraint> {
-
-    private static final ProviderId PID = new ProviderId("core", "org.onlab.onos.core", true);
-    @Reference(cardinality = ReferenceCardinality.MANDATORY_UNARY)
-    protected IntentExtensionService intentManager;
-
-    @Reference(cardinality = ReferenceCardinality.MANDATORY_UNARY)
-    protected TopologyService topologyService;
-
-    @Reference(cardinality = ReferenceCardinality.MANDATORY_UNARY)
-    protected LinkResourceService resourceService;
-
-    @Activate
-    public void activate() {
-        intentManager.registerCompiler(PointToPointIntentWithBandwidthConstraint.class, this);
-    }
-
-    @Deactivate
-    public void deactivate() {
-        intentManager.unregisterCompiler(PointToPointIntent.class);
-    }
-
-    @Override
-    public List<Intent> compile(PointToPointIntentWithBandwidthConstraint intent) {
-        Path path = getPath(intent.ingressPoint(), intent.egressPoint(), intent.bandwidthRequest());
-
-        List<Link> links = new ArrayList<>();
-        links.add(DefaultEdgeLink.createEdgeLink(intent.ingressPoint(), true));
-        links.addAll(path.links());
-        links.add(DefaultEdgeLink.createEdgeLink(intent.egressPoint(), false));
-
-        return Arrays.asList(createPathIntent(new DefaultPath(PID, links, path.cost() + 2,
-                                                              path.annotations()),
-                                              intent));
-    }
-
-    /**
-     * Creates a path intent from the specified path and original
-     * connectivity intent.
-     *
-     * @param path   path to create an intent for
-     * @param intent original intent
-     */
-    private Intent createPathIntent(Path path,
-                                    PointToPointIntentWithBandwidthConstraint intent) {
-        LinkResourceRequest.Builder request = DefaultLinkResourceRequest.builder(intent.id(),
-                path.links())
-                // TODO - this seems awkward, maybe allow directly attaching a BandwidthRequest
-                .addBandwidthRequest(intent.bandwidthRequest().bandwidth().toDouble());
-        LinkResourceRequest bandwidthRequest  = request.build();
-        LinkResourceRequest[] bandwidthRequests = {bandwidthRequest};
-        return new PathIntent(intent.appId(),
-                              intent.selector(), intent.treatment(), path,
-                              bandwidthRequests);
-    }
-
-    /**
-     * Computes a path between two ConnectPoints.
-     *
-     * @param one start of the path
-     * @param two end of the path
-     * @return Path between the two
-     * @throws org.onlab.onos.net.intent.impl.PathNotFoundException if a path cannot be found
-     */
-    private Path getPath(ConnectPoint one, ConnectPoint two, final BandwidthResourceRequest bandwidthRequest) {
-        Topology topology = topologyService.currentTopology();
-        LinkWeight weight = new LinkWeight() {
-            @Override
-            public double weight(TopologyEdge edge) {
-                if (bandwidthRequest != null) {
-                    double allocatedBandwidth = 0.0;
-                    Iterable<ResourceRequest> availableResources = resourceService.getAvailableResources(edge.link());
-                    for (ResourceRequest availableResource : availableResources) {
-                        if (availableResource.type() == ResourceType.BANDWIDTH) {
-                            BandwidthResourceRequest bandwidthRequest = (BandwidthResourceRequest) availableResource;
-                            allocatedBandwidth += bandwidthRequest.bandwidth().toDouble();
-                        }
-                    }
-
-                    // TODO this needs to be discovered from switch/ports somehow
-                    double maxBandwidth = 1000;
-
-                    double availableBandwidth = maxBandwidth - allocatedBandwidth;
-                    if (availableBandwidth >= bandwidthRequest.bandwidth().toDouble()) {
-                        return 1;
-                    } else {
-                        return -1;
-                    }
-                } else {
-                    return 1;
-                }
-            }
-        };
-
-        Set<Path> paths = topologyService.getPaths(topology,
-                one.deviceId(),
-                two.deviceId(),
-                weight);
-
-        if (paths.isEmpty()) {
-            throw new PathNotFoundException("No packet path from " + one + " to " + two);
-        }
-        // TODO: let's be more intelligent about this eventually
-        return paths.iterator().next();
-    }
-}