Web Notes

A few months ago I decided to learn a big data. This sounds very complex and of course it is. All these strange names which actually tells nothing to person who is new in these area combined with different way of looking at data storage makes entire topic even more complex. However after reading N blogs and watching many, many tutorials today I finally had a chance to try to write some code. As in last week I managed to setup a Hortonworks distribution of Hadoop today I decided to connect to it from my .NET based application and this is what I will describe in this post. First things first I didn`t setup entire Hortonworks ecosystem from scratch - I`d love to but for now it`s far beyond my knowledge thus I decided to use a sandbox environment provided by Hortonworks. There are multiple different VMs available to download but in my case I`ve choose a Hyper-V. More about setting this environment up you can read here . Picture 1. Up and running sandbox environment. Now whe

In today post I want to describe how to optimize usage of a ADO.NET SqlDataReader class by using multi-threading. To present that lets me introduce a problem that I will try to solve.  Scenario : In a project we decided to move all data from a multiple databases to one data warehouse. It will be a good few terabytes of data or even more. Data transfer will be done by using a custom importer program. Problem : After implementing a database agnostic logic of generating and executing a query I realized that I can retrieve data from source databases faster that I can upload them to big data store through HTTP client -importer program. In other words, data reader is capable of reading data faster then I can process it an upload to my big data lake. Solution : As a solution for solving this problem I would like to propose one of a multi-thread design pattern called Producer/Consumer . In general this pattern consists of a two main classes where: Producer class is respons

Today I want to cover a very common scenario about how to create a HTTP client for a WebAPI 2 service. To present my implementation I will be using one of a Task<T> extension method that I described recently on my blog. Let`s start from defining an API service. In this example it udes a REST based WebApi service with the following implementation.   [ AllowAnonymous ]     public   class   CityController    {         ///   <summary>         ///  The city repository.         ///   </summary>         private   readonly   ICityRepository  cityRepository;         ///   <summary>         ///  Initializes a new instance of the  <see cref= "CityController"  />  class.         ///   </summary>         ///   <param name= "cityRepository" > The city repository. </param>         public  CityController( ICityRepository  cityRepository)        {             this .cityRepository = cityRepository;        }        

This was a very long break since I posted my last web note however it`s time to share some fresh experience with the developer community. Today I want to show one of a handy solution which allowed me to simplify a Task chaining in .NET 4.5.1. Let`s start from defining a problem which in this case is a Task.ContinueWith<TResult>  method and the way how it`s designed for a tasks chaining. So if you want to use a chaining by using this function, all the time you need to access a parent task result property which in many cases causes a lot of redundancy in the code. To demonstrate this I use a simple async WebApi2 GET cities  auto-complete function which will query a database and later map result set of entities to collection of data transfer objects (DTO). // !!BADLY DESIGNED CODE!! [ HttpGet ] public   async   Task < HttpResponseMessage > Get( string  query)     {           return   await   this .cityRepository .AutocompleteCityAsync(query) . C