diff --git a/src/glance.js b/src/glance.js
index 53c4300..bbfa0a1 100644
--- a/src/glance.js
+++ b/src/glance.js
@@ -43,15 +43,16 @@ export default class Glance extends AbstractService {
    * @param {{}} endpointConfig The configuration element for a specific glance endpoint.
    */
   constructor (endpointConfig) {
-    super();
-
     // Sanity checks.
     if (!endpointConfig || !endpointConfig.url) {
       throw new Error('An endpoint configuration is required.');
     }
     // Clone the config, so that this instance is immutable
     // at runtime (no modifying the config after the fact).
-    this._config = Object.assign({}, endpointConfig);
+    endpointConfig = Object.assign({}, endpointConfig);
+
+    super(endpointConfig.url, supportedGlanceVersions);
+    this._config = endpointConfig;
   }
 
   /**
@@ -76,37 +77,6 @@ export default class Glance extends AbstractService {
     return Promise.all([this.serviceEndpoint(), headerPromise]);
   }
 
-  /**
-   * Retrieve all the API versions available.
-   *
-   * @returns {Promise.<T>} A promise that will resolve with the list of API versions.
-   */
-  versions () {
-    return this.http
-      .httpGet(this._config.url)
-      .then((response) => response.json())
-      .then((body) => body.versions);
-  }
-
-  /**
-   * Retrieve the API version declaration that is currently in use by this glance API.
-   *
-   * @returns {Promise.<T>} A promise that will resolve with the specific API version.
-   */
-  version () {
-    return this
-      .versions()
-      .then((versions) => {
-        const version = versions.find((element) => {
-          return supportedGlanceVersions.indexOf(element.id) > -1;
-        });
-        if (version) {
-          return version;
-        }
-        throw new Error("No supported Glance API version available.");
-      });
-  }
-
   /**
    * Return the root API endpoint for the current supported glance version.
    *
diff --git a/src/keystone.js b/src/keystone.js
index fd774c3..eee0961 100644
--- a/src/keystone.js
+++ b/src/keystone.js
@@ -23,15 +23,16 @@ export default class Keystone extends AbstractService {
    * @see http://docs.openstack.org/developer/os-client-config/#site-specific-file-locations
    */
   constructor (cloudConfig) {
-    super();
-
     // Sanity checks.
     if (!cloudConfig) {
       throw new Error('A configuration is required.');
     }
     // Clone the config, so that this instance is immutable
     // at runtime (no modifying the config after the fact).
-    this.cloudConfig = Object.assign({}, cloudConfig);
+    cloudConfig = Object.assign({}, cloudConfig);
+
+    super(cloudConfig.auth.auth_url, supportedKeystoneVersions);
+    this.cloudConfig = cloudConfig;
   }
 
   /**
@@ -87,31 +88,8 @@ export default class Keystone extends AbstractService {
    * @returns {Promise.<T>} A promise that will resolve with the list of API versions.
    */
   versions () {
-    return this.http
-      .httpGet(this.cloudConfig.auth.auth_url)
-      .then((response) => response.json())
-      .then((body) => {
-        return body.versions.values;
-      });
-  }
-
-  /**
-   * Retrieve the API version declaration that is currently in use by this keystone
-   * instance.
-   *
-   * @returns {Promise.<T>} A promise that will resolve with the specific API version.
-   */
-  version () {
-    return this
-      .versions()
-      .then((versions) => {
-        for (let version of versions) {
-          if (supportedKeystoneVersions.indexOf(version.id) > -1) {
-            return version;
-          }
-        }
-        throw new Error("No supported Keystone API version available.");
-      });
+    return super.versions()
+      .then((versions) => versions.values);
   }
 
   /**
diff --git a/src/util/abstract_service.js b/src/util/abstract_service.js
index 11ba0d3..adfebfe 100644
--- a/src/util/abstract_service.js
+++ b/src/util/abstract_service.js
@@ -16,13 +16,20 @@
 
 import Http from './http';
 
-/**
- * An abstract implementation of our services, which includes logic common to all of our services.
- *
- * @author Michael Krotscheck
- */
 export default class AbstractService {
 
+  /**
+   * This class provides an abstract implementation of our services, which includes logic common to
+   * all of our services.
+   *
+   * @param {string} endpointUrl The endpoint URL.
+   * @param {Array} supportedVersions The list of all supported versions.
+   */
+  constructor (endpointUrl, supportedVersions) {
+    this._endpointUrl = endpointUrl;
+    this._supportedVersions = supportedVersions;
+  }
+
   /**
    * Our HTTP service instance.
    *
@@ -34,4 +41,43 @@ export default class AbstractService {
     }
     return this._http;
   }
+
+  /**
+   * List of all supported versions.
+   *
+   * @returns {Array} The list of all supported versions, or empty array.
+   */
+  get supportedVersions () {
+    return this._supportedVersions || [];
+  }
+
+  /**
+   * Retrieve all the API versions available.
+   *
+   * @returns {Promise.<T>} A promise that will resolve with the list of API versions.
+   */
+  versions () {
+    return this.http
+      .httpGet(this._endpointUrl)
+      .then((response) => response.json())
+      .then((body) => body.versions);
+  }
+
+  /**
+   * Retrieve the API version declaration that is currently in use by this instance.
+   *
+   * @returns {Promise.<T>} A promise that will resolve with the specific API version.
+   */
+  version () {
+    return this
+      .versions()
+      .then((versions) => {
+        for (let version of versions) {
+          if (this.supportedVersions.indexOf(version.id) > -1) {
+            return version;
+          }
+        }
+        throw new Error("No supported API version available.");
+      });
+  }
 }