Skip to main content

Shared Access Signature and URL encoding on Windows Azure

Playing a little with Shared Access Signature was quite nice. In this moment this new functionality has a great potential. Playing a little with it I found an odd bug that I introduce from the code. From the start you need to know that this bug was generated by me and the cause of it was not Windows Azure.
Normally after we generate the access signature we are adding it to the URL that we want to access and we get a code similar to this:
var accessSignature = myTable.GetSharedAccessSignature(…);
string accessURL = tableAccessURL + … + accessSignature;
Uri accessUri = new Uri(accessURL);
string myAccessLink = accessUri.ToString();
The only problem here is that the accessSignature can contains specials characters like ‘=’ or ‘+’. This kind of characters needs to be encoded in the URL. Because of this from time to time we will get an URL that is not valid. In my case last time I got an access signature that contained this kind of specials characters for 4 times in a row. Because of this we cannot accept this kind of solutions.
A better way to get the string of an Uri object is to use AbsoluteUri for example. Or any other method that know to encode the URL characters. Using this method we will not need to worry about encoding problems. The code should look like this:
var accessSignature = myTable.GetSharedAccessSignature(…);
string accessURL = tableAccessURL + … + accessSignature;
Uri accessUri = new Uri(accessURL);
string myAccessLink = accessUri.AbsoluteUri();
Another solution for our problem is to use “EscapeUriString” method of the uri. This will do the same think for us.
In conclusion we should be carefully about how we convert any kind of Uri to a string and know very well what kind of characters can appear in it. If the URL that is generated doesn’t need to be read by a user I will also try to escape the uri string using any solutions that is available.


Popular posts from this blog

ADO.NET provider with invariant name 'System.Data.SqlClient' could not be loaded

Today blog post will be started with the following error when running DB tests on the CI machine:
threw exception: System.InvalidOperationException: The Entity Framework provider type 'System.Data.Entity.SqlServer.SqlProviderServices, EntityFramework.SqlServer' registered in the application config file for the ADO.NET provider with invariant name 'System.Data.SqlClient' could not be loaded. Make sure that the assembly-qualified name is used and that the assembly is available to the running application. See for more information. at System.Data.Entity.Infrastructure.DependencyResolution.ProviderServicesFactory.GetInstance(String providerTypeName, String providerInvariantName) This error happened only on the Continuous Integration machine. On the devs machines, everything has fine. The classic problem – on my machine it’s working. The CI has the following configuration:

TeamCity.NET 4.51EF 6.0.2VS2013
It seems that there …

GET call of REST API that contains '/'-slash character in the value of a parameter

Let’s assume that we have the following scenario: I have a public HTTP endpoint and I need to post some content using GET command. One of the parameters contains special characters like “\” and “/”. If the endpoint is an ApiController than you may have problems if you encode the parameter using the http encoder.
using (var httpClient = new HttpClient()) { httpClient.BaseAddress = baseUrl; Task<HttpResponseMessage> response = httpClient.GetAsync(string.Format("api/foo/{0}", "qwert/qwerqwer"))); response.Wait(); response.Result.EnsureSuccessStatusCode(); } One possible solution would be to encode the query parameter using UrlTokenEncode method of HttpServerUtility class and GetBytes method ofUTF8. In this way you would get the array of bytes of the parameter and encode them as a url token.
The following code show to you how you could write the encode and decode methods.

Entity Framework (EF) TransactionScope vs Database.BeginTransaction

In today blog post we will talk a little about a new feature that is available on EF6+ related to Transactions.
Until now, when we had to use transaction we used ‘TransactionScope’. It works great and I would say that is something that is now in our blood.
using (var scope = new TransactionScope(TransactionScopeOption.Required)) { using (SqlConnection conn = new SqlConnection("...")) { conn.Open(); SqlCommand sqlCommand = new SqlCommand(); sqlCommand.Connection = conn; sqlCommand.CommandText = ... sqlCommand.ExecuteNonQuery(); ... } scope.Complete(); } Starting with EF6.0 we have a new way to work with transactions. The new approach is based on Database.BeginTransaction(), Database.Rollback(), Database.Commit(). Yes, no more TransactionScope.
In the followi…