new file mode 100644
--- /dev/null
+++ b/strophe.rsm.js
@@ -0,0 +1,52 @@
+//import { $build, Strophe } from 'strophe.js';
+
+Strophe.addNamespace('RSM', 'http://jabber.org/protocol/rsm');
+
+Strophe.RSM = function(options) {
+  this.attribs = ['max', 'first', 'last', 'after', 'before', 'index', 'count'];
+
+  if (typeof options.xml != 'undefined') {
+    this.fromXMLElement(options.xml);
+  } else {
+    for (var ii = 0; ii < this.attribs.length; ii++) {
+      var attrib = this.attribs[ii];
+      this[attrib] = options[attrib];
+    }
+  }
+};
+
+Strophe.RSM.prototype = {
+  toXML: function() {
+    var xml = $build('set', {xmlns: Strophe.NS.RSM});
+    for (var ii = 0; ii < this.attribs.length; ii++) {
+      var attrib = this.attribs[ii];
+      if (typeof this[attrib] != 'undefined') {
+        xml = xml.c(attrib).t(this[attrib].toString()).up();
+      }
+    }
+    return xml.tree();
+  },
+
+  next: function(max) {
+    var newSet = new Strophe.RSM({max: max, after: this.last});
+    return newSet;
+  },
+
+  previous: function(max) {
+    var newSet = new Strophe.RSM({max: max, before: this.first});
+    return newSet;
+  },
+
+  fromXMLElement: function(xmlElement) {
+    for (var ii = 0; ii < this.attribs.length; ii++) {
+      var attrib = this.attribs[ii];
+      var elem = xmlElement.getElementsByTagName(attrib)[0];
+      if (typeof elem != 'undefined' && elem !== null) {
+        this[attrib] = Strophe.getText(elem);
+        if (attrib == 'first') {
+          this.index = elem.getAttribute('index');
+        }
+      }
+    }
+  }
+};