Archives
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Multitenancy in SQL Azure
If you are building a SaaS application in Windows Azure that relies on SQL Azure, it’s probably that you will need to support multiple tenants at database level.
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Using MAC Authentication for simple Web API’s consumption
For simple scenarios of Web API consumption where identity delegation is not required, traditional http authentication schemas such as basic, certificates or digest are the most used nowadays. All these schemas rely on sending the caller credentials or some representation of it in every request message as part of the Authorization header, so they are prone to suffer phishing attacks if they are not correctly secured at transport level with https.
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await, WhenAll, WaitAll, oh my!!
If you are dealing with asynchronous work in .NET, you might know that the Task class has become the main driver for wrapping asynchronous calls. Although this class was officially introduced in .NET 4.0, the programming model for consuming tasks was much more simplified in C# 5.0 in .NET 4.5 with the addition of the new async/await keywords. In a nutshell, you can use these keywords to make asynchronous calls as if they were sequential, and avoiding in that way any fork or callback in the code. The compiler takes care of the rest.
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Unit testing ASP.NET Web API controllers that rely on the UrlHelper
UrlHelper is the class you can use in ASP.NET Web API to automatically infer links from the routing table without hardcoding anything. For example, the following code uses the helper to infer the location url for a new resource,
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Doing unit and integration tests with the Web API HttpClient
One of the nice things about the new HttpClient in System.Net.Http is the support for mocking responses or handling requests in a http server hosted in-memory. While the first option is useful for scenarios in which we want to test our client code in isolation (unit tests for example), the second one enables more complete integration testing scenarios that could include some more components in the stack such as model binders or message handlers for example.
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Consuming the Amazon S3 service from a Win8 Metro Application
As many of the existing Http APIs for Cloud Services, AWS also provides a set of different platform SDKs for hiding many of complexities present in the APIs. While there is a platform SDK for .NET, which is open source and available in C#, that SDK does not work in Win8 Metro Applications for the changes introduced in WinRT. WinRT offers a complete different set of APIs for doing I/O operations such as doing http calls or using cryptography for signing or encrypting data, two aspects that are absolutely necessary for consuming AWS. All the I/O APIs available as part of WinRT are asynchronous, and uses the TPL model for .NET applications (HTML and JavaScript Metro applications use a model based in promises, which is similar concept).
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Binding form data in ASP.NET Web API
One scenario that is very common in ASP.NET MVC is to bind form data (data posted with the media type application/x-www-form-urlencoded) to individual parameters or a form collection in a controller action. However, that scenario does not work quite the same in ASP.NET Web API as the body content is treated a forward-only stream that can only be read once.
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Implementing synchronous MediaTypeFormatters in ASP.NET Web API
One of main characteristics of MediaTypeFormatter’s in ASP.NET Web API is that they leverage the Task Parallel Library (TPL) for reading or writing an model into an stream. When you derive your class from the base class MediaTypeFormatter, you have to either implement the WriteToStreamAsync or ReadFromStreamAsync methods for writing or reading a model from a stream respectively.
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HTML 5 para dispositivos mobiles – Proyecto Liike
La serie de videos que grabe con Miguel Angel Saenz y Ariel Schapiro de Microsoft Argentina acerca del proyecto “Liike” de Patterns & Practices para desarrollos de aplicaciones mobiles con HTML 5 ha sido publicada en channel9.
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Apache Cordova. A new alternative for developing native apps in Win Phone 7
Apache Cordova is one of those projects that recently caught my attention for developing applications in mobile. This project previously known as PhoneGap was donated by Adobe to the Apache Foundation to be part of a new and attractive open source alternative for developing mobile applications. If you haven’t heard of it before, it basically provides the required infrastructure to run native applications in different mobile platforms such as IOS, Android, and Windows Phone 7 using an hybrid approach with an embedded browser. There is a thin native layer that provides access to different native features in phone through an standard object model in JavaScript, so the developers can write their applications using HTML 5 and have access to different features through that model. Therefore, the two most important components in this project are the native layer and the JavaScript component model, which are supported across the different platforms.
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Increasing your system reliability with the Azure Service Bus Queues
A common scenario for many web applications running in the cloud is to integrate with existing systems through web services (no matter the messaging style they use). Although in these scenarios, an SLA is typically used as an agreement between the two parties to assure certain level of availability, many things can still fail. Therefore, it is always a good idea to have a mechanism in place to handle any possible error condition and retry the execution when it is possible.
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Authenticating your windows domain users in the cloud
Moving to the cloud can represent a big challenge for many organizations when it comes to reusing existing infrastructure. For applications that drive existing business processes in the organization, reusing IT assets like active directory represent good part of that challenge. For example, a new web mobile application that sales representatives can use for interacting with an existing CRM system in the organization.
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Debugging Node.js applications for Windows Azure
In case you are developing a new web application with Node.js for Windows Azure, you might notice there is no easy way to debug the application unless you are developing in an integrated IDE like Cloud9. For those that develop applications locally using a text editor (or WebMatrix) and Windows Azure Powershell for Node.js, it requires some steps not documented anywhere for the moment.
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Building Hypermedia Web APIs
Hypermedia is one of those concepts really hard to grasp when building Http aware APIs (or Web API’s). As human beings, we are constantly dealing with hypermedia in the existing web by following links or posting data from some forms that take us to a next level.
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Doing DI with Autofac in ASP.NET Web API
ASP.NET Web API provides a very similar model to MVC for resolving dependencies using a service locator pattern. What you basically do is to provide the implementation of that service locator to return any of the requested dependencies, and that implementation is typically tied to a DI container.
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Handling exceptions in your ASP.NET Web API
The Http status codes for reporting errors to clients can mainly be categorized on two groups, client errors and server errors. Any status code under 500 is considered an issue generated by something wrong on the request message sent by the client. For example, 404 for resource not found, 400 for bad request (some invalid data in the request message) or 403 for forbidden (an unauthorized operation) are some of the most well know client errors. On the hand, any other code over 500 is considered as a problem on the server side such as 500 for internal server error or 503 for server unavailable. This kind of error means that something unexpected happened on the server side while processing the request but it is not the client fault.
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Validating your models in ASP.NET Web API
One of the nice things about having a single extensibility model between ASP.NET MVC and Web API is that you can get many of the great MVC features for free. Model binding and validation is one of them.
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Integrating Backbone.js with ASP.NET Web API
In case you did not see the latest news, what we used to know as WCF Web API was recently rebranded and included in ASP.NET MVC 4 as ASP.NET Web API. While both frameworks are similar in essence with focus on HTTP, the latter was primarily designed for building HTTP services that don’t typically require an user intervention. For example, some AJAX endpoints or a Web API for a mobile application. While you could use ASP.NET MVC for implementing those kind of services, that would require some extra work for implementing things right like content-negotiation, documentation, versioning, etc. What really matter is that both framework share many of the extensibility points like model binders, filters or routing to name a few.
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Hacking the browser cache with JQuery and ASP.NET MVC
Although JQuery provides a very good support for caching responses from AJAX calls in the browser, it is always good to know how you can use http as protocol for making an effective use of it.
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AgileSight, my new venture
Another important milestone in my career started three years ago when I joined Tellago. I convinced my friend Jesus to hire me, and I would eventually move to the United States with my family to work in the company. That never occurred for some personal things, but I fortunately had a chance to create an excellent team of very talented people in Argentina. I started myself working remotely from Argentina, and the things went so well for the company that we end up hiring more than 15 great architects down here in Argentina. Creating this team was a very interesting and completely new challenge in my career.
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The rise of Single Page Applications (SPA) in Web Mobile
Limited connectivity is one of the main challenges in web mobile. The stateless nature of http causes that content and associated static files like scripts or images be transmitted over the wire every time a page is fully refreshed (assuming http caching is not implemented correctly). Diverse techniques have emerged over the years to solve part of that problem by using the browser AJAX support. One of these techniques, which drastically changed the way we develop web applications is know as single page applications.
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Implementing resource oriented controllers in ASP.NET MVC
One common problem with the naming convention and default routing mechanism in ASP.NET MVC is that we tend to group actions in a controller for sharing an URL space. This basically leads to complex controllers with a lot of unrelated methods that break the SOLID principles. Too many responsibilities in a simple class affects maintainability in the long run and causes secondary effects that complicates unit testing. For example, we usually end up with class constructors that receives too many dependencies as it is discussed here in SO.
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The “Liike” project. Mobile Web guidance from Microsoft P&P
Microsoft Patterns & Practices has recently started a new project whose codename is “Liike” (pronounced as LEEE-keh) for delivering guidance and a reference application in the mobile web space. As many of the recent initiatives started by different teams in Microsoft, this project will also be hosted in GitHub under http://liike.github.com/. All the artifacts, patterns and code generated during the project will be shared as part of that project.