diff --git a/js/Closure.js b/js/Closure.js
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+/* 
+ * @author: ucla-cs
+ * See COPYING for copyright and distribution information.
+ * Provide the callback closure for the async communication methods in the NDN class.
+ * This is a port of Closure.py from PyCCN, written by: 
+ * Derek Kulinski <takeda@takeda.tk>
+ * Jeff Burke <jburke@ucla.edu>
+ */
+
+/*
+ * Create a subclass of Closure and pass an object to async calls.
+ */
+var Closure = function Closure() {
+	// I don't think storing NDN's closure is needed
+	// and it creates a reference loop, as of now both
+	// of those variables are never set -- Derek
+	//
+	// Use instance variables to return data to callback
+	this.ndn_data = null;  // this holds the ndn_closure
+    this.ndn_data_dirty = false;
+};
+
+// Upcall result
+Closure.RESULT_ERR               = -1; // upcall detected an error
+Closure.RESULT_OK                =  0; // normal upcall return
+Closure.RESULT_REEXPRESS         =  1; // reexpress the same interest again
+Closure.RESULT_INTEREST_CONSUMED =  2; // upcall claims to consume interest
+Closure.RESULT_VERIFY            =  3; // force an unverified result to be verified
+
+// Upcall kind
+Closure.UPCALL_FINAL              = 0; // handler is about to be deregistered
+Closure.UPCALL_INTEREST           = 1; // incoming interest
+Closure.UPCALL_CONSUMED_INTEREST  = 2; // incoming interest, someone has answered
+Closure.UPCALL_CONTENT            = 3; // incoming verified content
+Closure.UPCALL_INTEREST_TIMED_OUT = 4; // interest timed out
+Closure.UPCALL_CONTENT_UNVERIFIED = 5; // content that has not been verified
+Closure.UPCALL_CONTENT_BAD        = 6; // verification failed
+
+/*
+ * Override this in your subclass.
+ * If you're getting strange errors in upcall()
+ * check your code whether you're returning a value.
+ */
+Closure.prototype.upcall = function(kind, upcallInfo) {
+	//dump('upcall ' + this + " " + kind + " " + upcallInfo + "\n");
+	return Closure.RESULT_OK;
+};
+
+var UpcallInfo = function UpcallInfo(ndn, interest, matchedComps, contentObject) {
+	this.ndn = ndn;  // NDN object (not used)
+	this.interest = interest;  // Interest object
+	this.matchedComps = matchedComps;  // int
+	this.contentObject = contentObject;  // Content object
+};
+
+UpcallInfo.prototype.toString = function() {
+	var ret = "ndn = " + this.ndn;
+	ret += "\nInterest = " + this.interest;
+	ret += "\nmatchedComps = " + this.matchedComps;
+	ret += "\nContentObject: " + this.contentObject;
+	return ret;
+}