Monday 28 April 2014

Group Policy prevents Chrome Sync of bookmarks

My Chrome browser was disabled from Syncing bookmarks. It transpires Group Policy was preventing it.


Some of the appropriate keys are here:

Tuesday 22 April 2014


JSONP allows GET verbs to be passed across domains. But it is restricted only to GET verbs. Custom or standard headers cannot be added, so you cannot include ETag when calling a REST service to use the cache where possible.

The more modern technique is to use CORS. This works for more modern browsers.

To get CORS to work with AngularJS, first add the code:

var dashboard = angular.module('dashboardApp', []);

dashboard.config(['$httpProvider', function ($httpProvider) {
    $httpProvider.defaults.useXDomain = true;

The useXDomain means the browser will send the Origin: http://serverhost header in the request.
The request can now be changed from

            'method': 'JSONP',
            'url': endurTradeServiceUrl + '?callback=JSON_CALLBACK',


            'method': 'GET',
            'url': endurTradeServiceUrl,

However if you look in Firebug, the server still shows no response:

Note that the Content-Length is 715 bytes but firebug shows no data:

This is because the browser's Same Origin policy is working. Now we need to go server-side and add the following header to the response:

public HttpResponseMessage Get()
            var cache = ObjectFactory.GetInstance();

            var response = Request.CreateResponse(HttpStatusCode.OK, cache.Strategies);
            response.Headers.Add("Access-Control-Allow-Origin", "*");
            return response;

And now it will work. Note that the wildcard for the response header is not best practice.

Now for the headers. If we have the code to add custom headers:

            'method': 'GET',
            'url': endurTradeServiceUrl,
            headers: {
                'if-none-match' : 'Today',
                'mycustom' : 'Bob'

Then go back to Firefox we can see that the client is now calling the OPTIONS method and requesting permission to use the headers with the Access-Control-Request-Headers header. This is the CORS "preflight" request:


The browser can skip the preflight request if the following conditions are true:

The request method is GET, HEAD, or POST, **and**
The application does not set any request headers other than Accept, Accept-Language, Content-Language, Content-Type, or Last-Event-ID, **and**
The Content-Type header (if set) is one of the following:
 - application/x-www-form-urlencoded
 - multipart/form-data
 - text/plain

As we are sending JSON and custom headers, these conditions are not met and so the preflight request is raised.

Now to handle the preflight:
Install the NuGet Package Microsoft.AspNet.WebApi.Cors.

Add the following code to WebApiConfig.cs

public static void Register(HttpConfiguration config)
            var enableCorsAttribute = new EnableCorsAttribute("*", "*", "GET, PUT, POST, DELETE, OPTIONS"); 

                name: "DefaultApi",
                routeTemplate: "api/{controller}/{id}",
                defaults: new { id = RouteParameter.Optional }

and you can then remove the lines
response.Headers.Add("Access-Control-Allow-Origin", "*");

from the controller actions.
The server
is now handling the Options message:

You may wish to read a header from the server. This may be useful for example if you want to store the ETag and reuse it for subsequent requests, thus using the full caching capability. If you want to be able to read a header from the server, the server needs to add the line

response.Headers.Add("Access-Control-Expose-Headers", "ETag");

NOTE: You CANNOT use the wildcard ("*") for Access-Control-Expose-Headers - it is rejected by Firefox and Chrome. It has to be a comma-separated list of headers.

MSDN Blogs
CORS support in ASP.NET

Tuesday 15 April 2014

CSS URLs within MVCx

To allow CSS URLs to work within an MVC app:
Move your Images folder to the Content folder, and use this in your CSS:
background-image: url(Images/login-box-backg.png) no-repeat left top;
Your folder structure should look like this:
  • Content
    -- Images
    ---- login-box-backg.png
    -- Site.css

Note a leading slash should not be used. All paths then within the CSS URL are relative to the Content folder.

Monday 14 April 2014

Failing to dispose of a Rabbit Client makes application hang on shutdown

If you fail to dispose of a Rabbit Client then it will prevent an application from shutting down.

Driving the DLR in Open BVE - it won't move initially

1: Firstly when it first when it loads you will be at the BANK HEADSHUNT.

2: put the brake to B8

3: put the reverser to F

4: press the DEL key to select drive mode

5: press the SPACE BAR (Auto Mode Only)

and you should be moving if you are not then repeat steps 2, 3 & 4 again

P.S. I know the speeds are not correct by the sim but you go by the Speedo on the EDP not the F10 Speed of the sim.

(OpenBVE users) in Auto mode you might come across a train in front of you if so press the Emergency Stop button "Q" because the SelTrac plug-in only simulates speed not signals it will only do both if you switch A.I mode on as well.

Make sure that first you have selected ATP Manual and you will be able to drive at line speed but if you have selected FWD then you will only be able to do 30km/h because this is Emergency shunt and is limited to 30 km/h and is only used to correct the stopping position or drive without Automatic Train Protection just follow the instructions above.

Minecraft Spawn World

To set the default spawn world:

/mv conf firstspawnworld myworld