here are further enhancements to the IHttpAgentHandler and to BaseHttpServer (from awebb)

i've added the OSHttpStatusCodes enumeration of HTTP status codes, have adapted 
BaseHttpServer to use those.

then RestPlugin now has proper Failure handling returning proper HTTP status
codes. Regions/POSTHandler is work-in-progress.

OpenSim/ApplicationPlugins/Rest/Regions/GETHandler.cs

@@ -67,18 +67,18 @@ namespace OpenSim.ApplicationPlugins.Rest.Regions
             try
             {
                 // param empty: regions list
-                if (String.IsNullOrEmpty(param)) return GetHandlerRegions();
+                if (String.IsNullOrEmpty(param)) return GetHandlerRegions(httpResponse);
 
                 // param not empty: specific region
-                return GetHandlerRegion(param);
+                return GetHandlerRegion(httpResponse, param);
             }
             catch (Exception e) 
             {
-                return Failure("GET", e);
+                return Failure(httpResponse, OSHttpStatusCode.ServerErrorInternalError, "GET", e);
             }
         }
 
-        public string GetHandlerRegions()
+        public string GetHandlerRegions(OSHttpResponse httpResponse)
         {
             XmlWriter.WriteStartElement(String.Empty, "regions", String.Empty);
             foreach (Scene s in App.SceneManager.Scenes)
@@ -105,7 +105,7 @@ namespace OpenSim.ApplicationPlugins.Rest.Regions
             return XmlWriterResult;
         }
 
-        public string GetHandlerRegion(string param)
+        public string GetHandlerRegion(OSHttpResponse httpResponse, string param)
         {
             // be resilient and don't get confused by a terminating '/'
             param = param.TrimEnd(new char[]{'/'});
@@ -118,7 +118,8 @@ namespace OpenSim.ApplicationPlugins.Rest.Regions
 
             Scene scene = null;
             App.SceneManager.TryGetScene(regionID, out scene);
-            if (null == scene) return Failure("GET", "cannot find region");
+            if (null == scene) return Failure(httpResponse, OSHttpStatusCode.ClientErrorNotFound,
+                                              "GET", "cannot find region {0}", regionID.ToString());
 
             RegionDetails details = new RegionDetails(scene.RegionInfo);
 
@@ -143,25 +144,27 @@ namespace OpenSim.ApplicationPlugins.Rest.Regions
                 switch (comps[1].ToLower()) 
                 {
                 case "terrain":
-                    return RegionTerrain(scene);
+                    return RegionTerrain(httpResponse, scene);
 
                 case "stats":
-                    return RegionStats(scene);
+                    return RegionStats(httpResponse, scene);
 
                 case "prims":
-                    return RegionPrims(scene);
+                    return RegionPrims(httpResponse, scene);
                 }
             }
-            return Failure("GET", "too many parameters");
+            return Failure(httpResponse, OSHttpStatusCode.ClientErrorBadRequest,
+                           "GET", "too many parameters {0}", param);
         }
         #endregion GET methods
 
-        protected string RegionTerrain(Scene scene)
+        protected string RegionTerrain(OSHttpResponse httpResponse, Scene scene)
         {
-            return Failure("GET", "terrain not implemented");
+            return Failure(httpResponse, OSHttpStatusCode.ServerErrorNotImplemented,
+                           "GET", "terrain not implemented");
         }
 
-        protected string RegionStats(Scene scene)
+        protected string RegionStats(OSHttpResponse httpResponse, Scene scene)
         {
             int users = scene.GetAvatars().Count;
             int objects = scene.Entities.Count - users;
@@ -182,9 +185,10 @@ namespace OpenSim.ApplicationPlugins.Rest.Regions
             return XmlWriterResult;
         }
 
-        protected string RegionPrims(Scene scene)
+        protected string RegionPrims(OSHttpResponse httpResponse, Scene scene)
         {
-            return Failure("GET", "prims not implemented");
+            return Failure(httpResponse, OSHttpStatusCode.ServerErrorNotImplemented,
+                           "GET", "prims not implemented");
         }
     }
 }

OpenSim/ApplicationPlugins/Rest/Regions/POSTHandler.cs

@@ -0,0 +1,101 @@
+/*
+* Copyright (c) Contributors, http://opensimulator.org/
+* See CONTRIBUTORS.TXT for a full list of copyright holders.
+*
+* Redistribution and use in source and binary forms, with or without
+* modification, are permitted provided that the following conditions are met:
+*     * Redistributions of source code must retain the above copyright
+*       notice, this list of conditions and the following disclaimer.
+*     * Redistributions in binary form must reproduce the above copyright
+*       notice, this list of conditions and the following disclaimer in the
+*       documentation and/or other materials provided with the distribution.
+*     * Neither the name of the OpenSim Project nor the
+*       names of its contributors may be used to endorse or promote products
+*       derived from this software without specific prior written permission.
+*
+* THIS SOFTWARE IS PROVIDED BY THE DEVELOPERS ``AS IS'' AND ANY
+* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+* DISCLAIMED. IN NO EVENT SHALL THE CONTRIBUTORS BE LIABLE FOR ANY
+* DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
+* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+* 
+*/
+
+using System;
+using System.Threading;
+using System.Collections;
+using System.Collections.Generic;
+using System.IO;
+using System.Net;
+using System.Reflection;
+using System.Text.RegularExpressions;
+using System.Timers;
+using System.Xml;
+using System.Xml.Serialization;
+using libsecondlife;
+using Mono.Addins;
+using Nwc.XmlRpc;
+using Nini.Config;
+using OpenSim.Framework;
+using OpenSim.Framework.Console;
+using OpenSim.Framework.Servers;
+using OpenSim.Framework.Communications;
+using OpenSim.Region.Environment.Scenes;
+using OpenSim.ApplicationPlugins.Rest;
+
+namespace OpenSim.ApplicationPlugins.Rest.Regions
+{
+
+    public partial class RestRegionPlugin : RestPlugin
+    {
+        #region POST methods
+        public string PostHandler(string request, string path, string param, 
+                                  OSHttpRequest httpRequest, OSHttpResponse httpResponse)
+        {
+            // foreach (string h in httpRequest.Headers.AllKeys) 
+            //     foreach (string v in httpRequest.Headers.GetValues(h))
+            //         m_log.DebugFormat("{0} IsGod: {1} -> {2}", MsgID, h, v);
+
+            MsgID = RequestID;
+            m_log.DebugFormat("{0} POST path {1} param {2}", MsgID, path, param);
+
+            try
+            {
+                // param empty: new region post
+                if (!IsGod(httpRequest)) 
+                    // XXX: this needs to be turned into a FailureUnauthorized(...)
+                    return Failure(httpResponse, OSHttpStatusCode.ClientErrorUnauthorized,
+                                   "GET", "you are not god");
+
+                if (String.IsNullOrEmpty(param)) return CreateRegion(httpRequest, httpResponse);
+
+                return Failure(httpResponse, OSHttpStatusCode.ClientErrorNotFound, 
+                               "POST", "url {0} not supported", param);
+            }
+            catch (Exception e) 
+            {
+                return Failure(httpResponse, OSHttpStatusCode.ServerErrorInternalError, "POST", e);
+            }
+        }
+
+        public string CreateRegion(OSHttpRequest request, OSHttpResponse response)
+        {
+            XmlWriter.WriteStartElement(String.Empty, "regions", String.Empty);
+            foreach (Scene s in App.SceneManager.Scenes)
+            {
+                XmlWriter.WriteStartElement(String.Empty, "uuid", String.Empty);
+                XmlWriter.WriteString(s.RegionInfo.RegionID.ToString());
+                XmlWriter.WriteEndElement();
+            }
+            XmlWriter.WriteEndElement();
+            
+            return XmlWriterResult;
+        }
+        #endregion POST methods
+    }
+}

OpenSim/ApplicationPlugins/Rest/Regions/RestRegionPlugin.cs

@@ -92,6 +92,7 @@ namespace OpenSim.ApplicationPlugins.Rest.Regions
 
                 // add REST method handlers
                 AddRestStreamHandler("GET", "/regions/", GetHandler);
+                AddRestStreamHandler("POST", "/regions/", PostHandler);
             }
             catch (Exception e)
             {

OpenSim/ApplicationPlugins/Rest/RestPlugin.cs

@@ -241,6 +241,7 @@ namespace OpenSim.ApplicationPlugins.Rest
         }
 
         private List<RestStreamHandler> _handlers               = new List<RestStreamHandler>();
+        private Dictionary<string, IHttpAgentHandler> _agents   = new Dictionary<string, IHttpAgentHandler>();
 
         /// <summary>
         /// Add a REST stream handler to the underlying HTTP server.
@@ -271,14 +272,38 @@ namespace OpenSim.ApplicationPlugins.Rest
         /// </summary>
         /// <param name="agentName">name of agent handler</param>
         /// <param name="handler">agent handler method</param>
-        /// <returns>true when the plugin is disabled or the agent
+        /// <returns>false when the plugin is disabled or the agent
-        /// handler could not be added..</returns>
+        /// handler could not be added. Any generated exceptions are
+        /// allowed to drop through to the caller, i.e. ArgumentException.
+        /// </returns>
         public bool AddAgentHandler(string agentName, IHttpAgentHandler handler)
         {
             if (!IsEnabled) return false;
+            _agents.Add(agentName, handler);
             return _httpd.AddAgentHandler(agentName, handler);
         }
 
+        /// <summary>
+        /// Remove a powerful Agent handler from the underlying HTTP
+        /// server.
+        /// </summary>
+        /// <param name="agentName">name of agent handler</param>
+        /// <param name="handler">agent handler method</param>
+        /// <returns>false when the plugin is disabled or the agent
+        /// handler could not be removed. Any generated exceptions are
+        /// allowed to drop through to the caller, i.e. KeyNotFound.
+        /// </returns>
+        public bool RemoveAgentHandler(string agentName, IHttpAgentHandler handler)
+        {
+            if (!IsEnabled) return false;
+            if(_agents[agentName] == handler)
+            {
+                _agents.Remove(agentName);
+                return _httpd.RemoveAgentHandler(agentName, handler);
+            }
+            return false;
+        }
+
         /// <summary>
         /// Check whether the HTTP request came from god; that is, is
         /// the god_key as configured in the config section supplied
@@ -316,19 +341,30 @@ namespace OpenSim.ApplicationPlugins.Rest
                 _httpd.RemoveStreamHandler(h.HttpMethod, h.Path);
             }
             _handlers = null;
+            foreach (KeyValuePair<string,IHttpAgentHandler> h in _agents)
+            {
+                _httpd.RemoveAgentHandler(h.Key,h.Value);
+            }
+            _agents   = null;
         }
 
         /// <summary>
         /// Return a failure message.
         /// </summary>
         /// <param name="method">origin of the failure message</param>
-        /// <param name="message>failure message</param>
+        /// <param name="message">failure message</param>
         /// <remarks>This should probably set a return code as
         /// well. (?)</remarks> 
-        protected string Failure(string method, string message)
+        protected string Failure(OSHttpResponse response, OSHttpStatusCode status,
+                                 string method, string format, params string[] msg)
         {
-            m_log.ErrorFormat("{0} {1} failed: {2}", MsgID, method, message);
+            string m = String.Format(format, msg);
-            return String.Format("<error>{0}</error>", message);
+
+            response.StatusCode = (int)status;
+            response.StatusDescription = m;
+
+            m_log.ErrorFormat("{0} {1} failed: {2}", MsgID, method, m);
+            return String.Format("<error>{0}</error>", m);
         }
 
         /// <summary>
@@ -338,8 +374,14 @@ namespace OpenSim.ApplicationPlugins.Rest
         /// <param name="e">exception causing the failure message</param>
         /// <remarks>This should probably set a return code as
         /// well. (?)</remarks> 
-        public string Failure(string method, Exception e)
+        public string Failure(OSHttpResponse response, OSHttpStatusCode status, 
+                              string method, Exception e)
         {
+            string m = String.Format("exception occurred: {0}", e.Message);
+
+            response.StatusCode = (int)status;
+            response.StatusDescription = m;
+
             m_log.DebugFormat("{0} {1} failed: {2}", MsgID, method, e.ToString());
             m_log.ErrorFormat("{0} {1} failed: {2}", MsgID, method, e.Message);
 

OpenSim/Framework/Servers/BaseHttpServer.cs

@@ -120,6 +120,10 @@ namespace OpenSim.Framework.Servers
             return false;
         }
 
+        // Note that the agent string is provided simply to differentiate
+        // the handlers - it is NOT required to be an actual agent header
+        // value.
+
         public bool AddAgentHandler(string agent, IHttpAgentHandler handler)
         {
             if (!m_agentHandlers.ContainsKey(agent))
@@ -157,10 +161,10 @@ namespace OpenSim.Framework.Servers
 
                     IHttpAgentHandler agentHandler;
 
-                    if (TryGetAgentHandler(request.UserAgent, out agentHandler))
+                    if (TryGetAgentHandler(request, response, out agentHandler))
                     {
-                        m_log.DebugFormat("[HTTP-AGENT] Handler located for {0}", request.UserAgent);
+                        // m_log.DebugFormat("[HTTP-AGENT] Handler located for {0}", request.UserAgent);
-                        HandleAgentRequest(agentHandler, request, response);
+                        if(HandleAgentRequest(agentHandler, request, response))
 							return;
                     }
                 }
@@ -301,14 +305,14 @@ namespace OpenSim.Framework.Servers
             }
         }
 
-        private bool TryGetAgentHandler(string agent, out IHttpAgentHandler agentHandler)
+        private bool TryGetAgentHandler(OSHttpRequest request, OSHttpResponse response, out IHttpAgentHandler agentHandler)
         {
             agentHandler = null;
             try
             {
                 foreach(IHttpAgentHandler handler in m_agentHandlers.Values)
                 {
-                    if(handler.Match(agent))
+                    if(handler.Match(request, response))
                     {
                         agentHandler = handler;
                         return true;
@@ -472,7 +476,7 @@ namespace OpenSim.Framework.Servers
         /// <param name="request"></param>
         /// <param name="response"></param>
 
-        private void HandleAgentRequest(IHttpAgentHandler handler, OSHttpRequest request, OSHttpResponse response)
+        private bool HandleAgentRequest(IHttpAgentHandler handler, OSHttpRequest request, OSHttpResponse response)
         {
 
             // In the case of REST, then handler is responsible for ALL aspects of 
@@ -480,16 +484,26 @@ namespace OpenSim.Framework.Servers
 
             try
             {
-                handler.Handle(request, response);
+                return handler.Handle(request, response);
             }
             catch (Exception e)
+            {
+                // If the handler did in fact close the stream, then this will blow
+                // chunks, so that that doesn;t disturb anybody we throw away any
+                // and all exceptions raised. We've done our best to release the
+                // client.
+                try
                 {
                     m_log.Warn("[HTTP-AGENT]: Error - " + e.Message);
                     response.SendChunked   = false;
                     response.KeepAlive     = false;
-                response.StatusCode    = 500;
+                    response.StatusCode    = (int)OSHttpStatusCode.ServerErrorInternalError;
                     response.OutputStream.Close();
                 }
+                catch(Exception){}
+            }
+
+            return true;
 
         }
 
@@ -498,7 +512,7 @@ namespace OpenSim.Framework.Servers
             switch (request.HttpMethod)
             {
                 case "OPTIONS":
-                    response.StatusCode = 200;
+                    response.StatusCode = (int)OSHttpStatusCode.SuccessOk;
                     return;
 
                 default:
@@ -599,9 +613,9 @@ namespace OpenSim.Framework.Servers
             // We're forgoing the usual error status codes here because the client
             // ignores anything but 200 and 301
 
-            response.StatusCode = 200;
+            response.StatusCode = (int)OSHttpStatusCode.SuccessOk;
 
-            if (responsecode == 301)
+            if (responsecode == (int)OSHttpStatusCode.RedirectMovedPermanently)
             {
                 response.RedirectLocation = (string)responsedata["str_redirect_location"];
                 response.StatusCode = responsecode;
@@ -632,7 +646,7 @@ namespace OpenSim.Framework.Servers
         public void SendHTML404(OSHttpResponse response, string host)
         {
             // I know this statuscode is dumb, but the client doesn't respond to 404s and 500s
-            response.StatusCode = 200;
+            response.StatusCode = (int)OSHttpStatusCode.SuccessOk;
             response.AddHeader("Content-type", "text/html");
 
             string responseString = GetHTTP404(host);
@@ -659,7 +673,7 @@ namespace OpenSim.Framework.Servers
         public void SendHTML500(OSHttpResponse response)
         {
             // I know this statuscode is dumb, but the client doesn't respond to 404s and 500s
-            response.StatusCode = 200;
+            response.StatusCode = (int)OSHttpStatusCode.SuccessOk;
             response.AddHeader("Content-type", "text/html");
 
             string responseString = GetHTTP500();
@@ -738,6 +752,23 @@ namespace OpenSim.Framework.Servers
             m_HTTPHandlers.Remove(GetHandlerKey(httpMethod, path));
         }
 
+        // Remove the agent IF it is registered. Intercept the possible
+        // exception.
+
+        public bool RemoveAgentHandler(string agent, IHttpAgentHandler handler)
+        {
+            try
+            {
+                if(handler == m_agentHandlers[agent])
+                {
+                    m_agentHandlers.Remove(agent);
+                    return true;
+                }
+            }
+            catch(KeyNotFoundException) {}
+            return false;
+        }
+
         public string GetHTTP404(string host)
         {
             string file = Path.Combine(Util.configDir(), "http_404.html");

OpenSim/Framework/Servers/IHttpAgentHandler.cs

@@ -33,7 +33,7 @@ namespace OpenSim.Framework.Servers
 {
     public interface IHttpAgentHandler
     {
-        void Handle(OSHttpRequest req, OSHttpResponse resp);
+        bool Handle(OSHttpRequest req, OSHttpResponse resp);
-        bool Match(string agent);
+        bool Match(OSHttpRequest req, OSHttpResponse resp);
     }
 }

OpenSim/Framework/Servers/OSHttpStatusCodes.cs

@@ -0,0 +1,168 @@
+/*
+ * Copyright (c) Contributors, http://opensimulator.org/
+ * See CONTRIBUTORS.TXT for a full list of copyright holders.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *     * Redistributions of source code must retain the above copyright
+ *       notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above copyright
+ *       notice, this list of conditions and the following disclaimer in the
+ *       documentation and/or other materials provided with the distribution.
+ *     * Neither the name of the OpenSim Project nor the
+ *       names of its contributors may be used to endorse or promote products
+ *       derived from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE DEVELOPERS ``AS IS'' AND ANY
+ * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+ * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE CONTRIBUTORS BE LIABLE FOR ANY
+ * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+ * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+ * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
+ * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+ * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+namespace OpenSim.Framework.Servers
+{
+    /// <summary>
+    /// HTTP status codes (almost) as defined by W3C in
+    /// http://www.w3.org/Protocols/rfc2616/rfc2616-sec10.html
+    /// </summary>
+    public enum OSHttpStatusCode: int
+    {
+        // 1xx Informational status codes providing a provisional
+        // response.
+        // 100 Tells client that to keep on going sending its request
+        InfoContinue                          = 100,
+        // 101 Server understands request, proposes to switch to different
+        // application level protocol
+        InfoSwitchingProtocols                = 101,
+
+                                              
+        // 2xx Success codes
+        // 200 Request successful
+        SuccessOk                             = 200,
+        // 201 Request successful, new resource created
+        SuccessOkCreated                      = 201,
+        // 202 Request accepted, processing still on-going 
+        SuccessOkAccepted                     = 202,
+        // 203 Request successful, meta information not authoritative
+        SuccessOkNonAuthoritativeInformation  = 203,
+        // 204 Request successful, nothing to return in the body
+        SuccessOkNoContent                    = 204,
+        // 205 Request successful, reset displayed content
+        SuccessOkResetContent                 = 205,
+        // 206 Request successful, partial content returned
+        SuccessOkPartialContent               = 206,
+
+        // 3xx Redirect code: user agent needs to go somewhere else
+        // 300 Redirect: different presentation forms available, take
+        // a pick    
+        RedirectMultipleChoices               = 300,
+        // 301 Redirect: requested resource has moved and now lives
+        // somewhere else
+        RedirectMovedPermanently              = 301,
+        // 302 Redirect: Resource temporarily somewhere else, location
+        // might change
+        RedirectFound                         = 302,
+        // 303 Redirect: See other as result of a POST
+        RedirectSeeOther                      = 303,
+        // 304 Redirect: Resource still the same as before
+        RedirectNotModified                   = 304,
+        // 305 Redirect: Resource must be accessed via proxy provided
+        // in location field
+        RedirectUseProxy                      = 305,
+        // 307 Redirect: Resource temporarily somewhere else, location
+        // might change
+        RedirectMovedTemporarily              = 307,
+                                              
+        // 4xx Client error: the client borked the request
+        // 400 Client error: bad request, server does not grok what
+        // the client wants
+        ClientErrorBadRequest                 = 400,
+        // 401 Client error: the client is not authorized, response
+        // provides WWW-Authenticate header field with a challenge
+        ClientErrorUnauthorized               = 401,
+        // 402 Client error: Payment required (reserved for future use)
+        ClientErrorPaymentRequired            = 402,
+        // 403 Client error: Server understood request, will not
+        // deliver, do not try again.
+        ClientErrorForbidden                  = 403,
+        // 404 Client error: Server cannot find anything matching the
+        // client request. 
+        ClientErrorNotFound                   = 404,
+        // 405 Client error: The method specified by the client in the
+        // request is not allowed for the resource requested
+        ClientErrorMethodNotAllowed           = 405,
+        // 406 Client error: Server cannot generate suitable response
+        // for the resource and content characteristics requested by
+        // the client
+        ClientErrorNotAcceptable              = 406,
+        // 407 Client error: Similar to 401, Server requests that
+        // client authenticate itself with the proxy first
+        ClientErrorProxyAuthRequired          = 407,
+        // 408 Client error: Server got impatient with client and
+        // decided to give up waiting for the client's request to
+        // arrive
+        ClientErrorRequestTimeout             = 408,
+        // 409 Client error: Server could not fulfill the request for
+        // a resource as there is a conflict with the current state of
+        // the resource but thinks client can do something about this
+        ClientErrorConflict                   = 409,
+        // 410 Client error: The resource has moved somewhere else,
+        // but server has no clue where.
+        ClientErrorGone                       = 410,
+        // 411 Client error: The server is picky again and insists on
+        // having a content-length header field in the request
+        ClientErrorLengthRequired             = 411,
+        // 412 Client error: one or more preconditions supplied in the
+        // client's request is false
+        ClientErrorPreconditionFailed         = 412,
+        // 413 Client error: For fear of reflux, the server refuses to
+        // swallow that much data.
+        ClientErrorRequestEntityToLarge       = 413,
+        // 414 Client error: The server considers the Request-URI to
+        // be indecently long and refuses to even look at it.
+        ClientErrorRequestURITooLong          = 414,
+        // 415 Client error: The server has no clue about the media
+        // type requested by the client (contrary to popular belief it
+        // is not a warez server)
+        ClientErrorUnsupportedMediaType       = 415,
+        // 416 Client error: The requested range cannot be delivered
+        // by the server.
+        ClientErrorRequestRangeNotSatisfiable = 416,
+        // 417 Client error: The expectations of the client as
+        // expressed in one or more Expect header fields cannot be met
+        // by the server, the server is awfully sorry about this.
+        ClientErrorExpectationFailed          = 417,
+
+        // 5xx Server errors (rare)
+        // 500 Server error: something really strange and unexpected
+        // happened
+        ServerErrorInternalError              = 500,
+        // 501 Server error: The server does not do the functionality
+        // required to carry out the client request. not at
+        // all. certainly not before breakfast. but also not after
+        // breakfast. 
+        ServerErrorNotImplemented             = 501,
+        // 502 Server error: While acting as a proxy or a gateway, the
+        // server got ditched by the upstream server and as a
+        // consequence regretfully cannot fulfill the client's request
+        ServerErrorBadGateway                 = 502,
+        // 503 Server error: Due to unforseen circumstances the server
+        // cannot currently deliver the service requested. Retry-After
+        // header might indicate when to try again.
+        ServerErrorServiceUnavailable         = 503,
+        // 504 Server error: The server blames the upstream server
+        // for not being able to deliver the service requested and
+        // claims that the upstream server is too slow delivering the
+        // goods.
+        ServerErrorGatewayTimeout             = 504,
+        // 505 Server error: The server does not support the HTTP
+        // version conveyed in the client's request.
+        ServerErrorHttpVersionNotSupported    = 505,
+    }
+}