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Πρόσφατες Δημοσιεύσεις
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My comment at: http://visualstudio.uservoice.com/forums/121579-visual-studio-2015/suggestions/4272089-support-implicit-interfaces-for-code-reuse It would be nice indeed if one could define at the client object’s side a static interface that is a subset of the methods of a server (or serving if you prefer) object (it is only the view of the server that the client has gained knowledge of) that has been […]...
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It is rather unfortunate that C# doesn’t support constants in interfaces, whereas Java does. If IL (intermediate language) that C# usually compiles to (when not using AOT that is like in .NET Native or Xamarin iOS) doesn’t support this, then the compiler could create a special sealed class to carry the constants. Then, wherever they’re […]...
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This is the complete list of Visual Studio 2015 Extensions I’m using currently: Tagged: Extensions, Visual Studio...
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It would be nice if one could write in C# (and maybe in other .NET languages too): s = s.SomeMethodOfS(…)… as s .= SomeMethodOfS(…)… that is to have a .= operator, similar to += and other shorthand experession operators see screenshot for an example usecase from the opensource project FoscamController Ideally, usage of […]...
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It would be nice if one could rewrite this C# snippet: public SortedDictionary<string, UObject> GetObjects() { SortedDictionary<string, UObject> result = new SortedDictionary<string, UObject>(); using (ReadTransaction xact = namingSchema.ReadTransaction()) foreach (ObjectName.RowType row in ObjectName.object_name_(xact)) result.Add(row.name_, row.object_); return result; } in a more concise form like: public T GetObjects() where T=SortedDictionary<string, UObject> { T result […]...
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In this post I am going to demonstrate with a hands-on example how to use the popular NoSQL database MongoDB to store and retrieve data using Visual Studio 2015and ASP.Net MVC. When creating an application, any type of application (web, windows, distributed) all the data is stored and retrieved from a database. The most popular kind of databases that we are using to store and retrieve data are called Relational Databases and I have been using SQL Server as the RDBMS of choice for many years now. Data grows fast nowadays. We are having more applications than ever and databases grow rapidly. That fact alone has some serious implications. There is more demand for scale and speed. When you design a web application, a commercial web application e.g an ecommerce store, you know that the speed and scale of the e-shop will mean more customer conversions for your client. It is the demand for scale, speed, and fast application development that has brought on a new breed of databases, namely NoSQL databases. MongoDB is the...
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Many people use entity framework but are not aware of what deferred execution is and how it may affect their projects. In this article, we are going to have a little talk about it and see how things work. LINQ to entities and deferred execution We take into account that we all have some understanding of entity and LINQ or lambda expressions. To go through this post we created a table called Videogames containing four columns (ID, Name, MainCharacterName and Publisher) and filled it with some popular vintage videogames. Let's start with the following piece of code. string videogameNames = "" ; var MarioVideogames = db.Videogames.Where(v => v.MainCharacterName == "Mario" ); foreach ( var videogame in MarioVideogames) videogameNames += videogame.Name + "<br/>" ; Let's say our table contained only two Videogames having Mario MainCharacterName: Super...
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Duff Device on Wikipedia using System ; using System.Collections.Generic ; using System.Linq ; using System.Text ; namespace DuffDeviceFun { class Program { static void DuffDevice ( byte [] src, byte [] dest, int count) { unsafe { fixed ( byte * fromp = src, top = dest) { byte * from = fromp; byte * to = top; int n = (count + 7 ) / 8 ; switch (count % 8 ) { case 0 : goto LBL0; case 7 : goto LBL7; case 6 : goto LBL6; case 5 : goto LBL5; case 4 : goto LBL4; case 3 : goto LBL3; case 2 : goto LBL2; case 1 : goto LBL1; } LBL0: *to++ = * from ++; LBL7: *to++ = * from ++; LBL6: *to++ = * from ++; LBL5: *to++ = * from ++; LBL4: *to++ = * from ++; LBL3: *to++ = * from ++; LBL2: *to++ = * from ++; LBL1: *to++ = * from ++; if (--n > 0 ) goto LBL0; } } } static void Main ( string [] args) { string msg = "Demo Message!" ; var len = msg.Length * sizeof ( char ); byte [] from = new byte [len]; Buffer.BlockCopy(msg.ToCharArray(), 0 , from , 0 , len); byte [] to = new byte [ from .Length * sizeof ( char )]; DuffDevice(...
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Η δύναμη της συνήθειας είναι το μεγαλύτερο ναρκωτικό του μυαλού και δεν το αφήνει να σκεφτεί αποδοτικά. Αλήθεια πόσες φορές κάνουμε μηχανικά κάποια πράγματα επειδή τα έχουμε συνηθίσει στα τόσα χρόνια που κάνουμε αυτή την δουλειά ; http://www.sqlschool.gr/blog/get-all-tables-row-count-without-using-count-function-1058.aspx...
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Exploring the Kinect SDK v1.8 Developer Toolkit Browser application, I noticed some audio positioning visualizations at various samples (specifically at Audio Basics, Audio Explorer and Kinect Explorer samples), but I kept on looking for some simpler/cleaner sample code to return audio positioning info that would be easier to reuse. So I can across http://kinectaudioposition.codeplex.com that […]...
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In this post I am going to provide you with a hands-on example on how to take advantage of asynchronous execution using Entity Framework. EF 6 has the ability to execute a query and command asynchronously using DbContext. Entity Framework is an object-relational mapping (ORM) framework for the .NET Framework.EF addresses the problem of Object-relational impedance mismatch. I will not be talking about that mismatch because it is well documented in many sites on the Internet. Through that framework we can program against a conceptual application model instead of programming directly against a relational schema-model. By doing so we can decrease the amount of code we do write to access a data storage and thus decrease maintenance time. You can find many posts regarding Entity Framework in this blog. Before I go on with my hands-on example I would like to talk about asynchronous programming. Asynchronous programing is everywhere these days. It doesn't matter if you're on the client or the server. On the client, you...
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Τα User Defined Functions (UDF) είναι γνωστά στους περισσότερους. Η χρήση τους είναι μεγάλη αλλά αρκετές φορές χρησιμοποιούνται λάθος κυρίως λόγο της άγνοιας που υπάρχει γύρω από την εκτέλεση ενός UDF και ιδιαίτερα όταν αυτό εμπλέκεται μέσα σε ένα query. Οι περισσότεροι συγκρίνοντας το execution plan ενός query χωρίς UDF και με UDF βλέπουν ότι το query cost είναι μικρότερο σε αυτό που χρησιμοποιεί το UDF και αμέσως θεωρούν ότι αυτό είναι και το καλύτερο. Για ακόμα μια φορά θα τονίσω ότι δεν υπάρχει έτσι απλά καλό ή καλύτερο όλα είναι εξάρτηση από πολλούς παράγοντες όπως την ποσότητα και ποιότητα των δεδομένων των indexes κλπ http://www.sqlschool.gr/blog/sql-server-2016-new-features-the-sys-dm_exec_function_stats-dmv-1057.aspx...
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Managing and tuning the performance of relational databases is a challenging task that requires significant Read more...
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Καθημερινά ένας DBA ή DB developer έχει να αντιμετωπίσει αρκετούς αστάθμητους τις περισσότερες φορές παράγοντες που επηρεάζουν το performance. Πιστέψτε με ότι αυτό είναι μια δουλεία που απαιτεί σχολαστικότητα γνώση της αρχιτεκτονικής τόσο του SQL Server όσο και της database. Για να κάνεις αυτή την δουλεία θα πρέπει να έχει μελετήσει αρκετά και να έχεις κάνει αρκετή πρακτική εξάσκηση για την απόκτηση εμπειρίας. Ακόμα και ένας τέτοιος άνθρωπος πάντα επιζητά τρόπους να κάνει λιγότερο δύσκολη την δουλεία του και η χαρά του είναι μεγάλη όταν ανακαλύπτει ότι το αγαπημένο του εργαλείο έκδοση με την έκδοση του δίνει περισσότερες δυνατότητες για αυτό το task. Από τα βασικά εργαλεία μας στον SQL Server είναι τα Dynamic Management Views (DMV). Αρκετά από αυτά είναι κυρίαρχα εργαλεία στο performance troubleshooting. http://www.sqlschool.gr/blog/sql-server-2016-new-features-the-sys-dm_exec_session_wait_stats-dmv-1056.aspx...
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This is the second post in a series of posts where I talk about good coding practices when it comes to using Entity Framework as our data access layer when building our applications. You can read the first post of the series here . The main things to take away from that first post is to use projection whenever possible (do not query sql server for data that you do not want on the client) and to filter on the server (meaning SQL Server) which has a powerful engine to do that and not on the client. In this post I am going to provide you with a hands-on example on how to avoid writing your LINQ to Entities queries in a way that will hinder performance of your application. The aim of this post (hopefully a series of posts on performance and Entity Framework) is to highlight bad coding practices when architecting an applications that uses EF as the ORM to fetch and manipulate data from the data store. I am going to point out some practises and patterns that very often developers use and cause EF to create poor-performing...
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This is my answer at: http://stackoverflow.com/questions/31552082/vsix-installer-signaturedescription-could-not-be-created-for-the-signature-algo/ to the question on why some extensions fail to install at RC (Release Candidate) versions of Visual Studio 2015, showing error “SignatureDescription could not be created for the signature algorithm supplied”. Not sure if Microsoft fixed this on purpose or by accident, but this is very useful for people […]...
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In this post I am going to provide you with a hands-on example on how to avoid writing your LINQ to Entities queries in a way that will hinder performance of your application. The aim of this post (hopefully a series of posts on performance and Entity Framework) is to highlight bad coding practices when architecting an applications that uses EF as the ORM to fetch and manipulate data from the data store. I am going to point out some practises and patterns that very often developers use and cause EF to create poor-performing T-SQL statements. Entity Framework will always create T-SQL, the thing to keep in mind is that we have to make sure that this T-SQL code (that we cannot write ourselves since it is abstracted by EF) if it is poor then when passed to the SQL Server engine (through the optimiser and the creation of the execution plan) will cause our applications to perform poorly especially under heavy load. Let me talk a bit about query optimisation and T-SQL. T-SQL is declarative by nature. When we write T-SQL...
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Nice article about Akka.Net http://www.codeproject.com/Articles/1007161/A-Look-At-Akka-NET...
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We have already seen how to create a WCF service. This time we are going to see how to combine a WCF service with SSL security, which will be a trickier thing to do. To reach our goal, we need to take three steps. Step one is to create a WCF Service. Step two is to install a certificate for authentication. Step three is to bring the two first steps together. Since creating a secure socket layer for a website takes more than just a few words. I am planning on writing some future article about that. In order to apply the following methods, a reader should either already have a secure website or, if unable to wait, find a proper article since there are quite a lot out there. Concerning WCF services This is the article where we created a WCF service. However since this task is more complex, we will start by repeating a few things. To create a WCF service, we create a service (svc) file. This is where we place the code to execute when the service is requested. The svc...
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Το connection pooling είναι μια cache από database connections που σκοπό έχει αυτά που είναι ελεύθερα στην cache αυτή να μπορούν να επαναχρησιμοποιηθούν κάθε φορά που κάποιος ζητάει να κάνει connect στην database. Η χρησιμότητα του connection pooling είναι αρκετά σημαντική στην εκτέλεση διαδικασιών πάνω στην database από το application καθώς με αυτό τον τρόπο γίνεται αφενός γρηγορότερη επικοινωνία αφετέρου καταναλώνονται λιγότεροι πόροι. http://www.sqlschool.gr/blog/monitor-connection-pooling-as-sql-server-dba-1050.aspx...
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It would be nice if one could define methods inside other methods so that they are only accessible in the context of the parent method. In Pascal one could define them at the start of the parent method, before any other commands, but after local variables block, so they could also access the variables of […]...
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Trying to reuse the conditional value of a switch statment in C# at the fallback “default” code block of it, and looking up if that was supported in C#, I found the a related discussion at: http://stackoverflow.com/questions/29628507/c-sharp-get-switch-value-if-in-default-case I added a comment there and also elaborated it a bit more at a suggestion (PLEASE VOTE IT […]...
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This is my answer at http://stackoverflow.com/questions/4475391/wpf-silverlight-find-the-name-of-a-color Modified answer from Thomas Levesque to populate the Dictionary only when 1st needed, instead of taking the cost at startup (going to use at speech recognition-driven turtle graphics, so that user can pronounce known color names to change the turtle’s pen color) //Project: SpeechTurtle (http://SpeechTurtle.codeplex.com) //Filename: ColorUtils.cs //Version: 20150901 […]...
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While adding more voice commands at SpeechTurtle, I had to update the active legend where the available commands are displayed and their text is highlighted as the respective commands are recognized by the speech recognition engine (using .NET’s managed Speech API). A problem I faced was how to add a newline and prefixing the 2nd […]...
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Instead of having to write in C# speechRecognizer = CreateSpeechRecognizer(); if (speechRecognizer != null) { speechRecognizer.SomeProperty = someValue; speechRecognizer.SomeOtherProperty = someOtherValue; speechRecognizer.SpeechRecognized += SpeechRecognized; speechRecognizer.SpeechHypothesized += SpeechHypothesized; speechRecognizer.SpeechRecognitionRejected += SpeechRecognitionRejected; } I’d prefer to write: speechRecognizer = CreateSpeechRecognizer() { SomeProperty = someValue, SomeOtherProperty […]...
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