Friday, November 17, 2017

Creating WCF Service without .SVC File

This blog demonstrates how to create a WCF service without having physical .SVC File and after .net 4.0 release, we can create a WCF service without having svc file.

Windows Communication Foundation (WCF) is a framework for building service-oriented applications. Using WCF, you can send data as asynchronous messages from one service endpoint to another. A service endpoint can be part of a continuously available service hosted by IIS, or it can be a service hosted in an application

In general, WCF Service have .SVC File and Service Code File as shown below

This SVC file is a simply text file and which contains the below information, which allows to host WCF Service and respond to incoming request/message.

·         Language: (C# / VB)
·         Service (Name of the service) : MoneyTransfer
·         CodeBehind (The location of service code ) : MoneyTransfer.svc.cs

Here is an example of SVC file:

<%@ ServiceHost Language="C#" Debug="true" Service="MoneyTransfer" CodeBehind="Money.MoneyTransfer.svc.cs" %>

A .SVC file contains a WCF-specific processing directive (@ServiceHost) that allows the WCF hosting infrastructure to activate hosted services in response to incoming messages. This file contains the details required for WCF service to run it successfully.

CodeBehind File : MoneyTransfer.svc.cs

namespace Money

    public interface IMoneyTransfer
        bool Post(decimal money, int accountNumber);

        bool Withdrawal(decimal money, int accountNumber);

    public class MoneyTransfer : IMoneyTransfer
        public bool Post(decimal money, int accountNumber)
            throw new NotImplementedException();

        public bool Withdrawal(decimal money, int accountNumber)
            throw new NotImplementedException();


after .net 4.0 release, it allows to create a WCF service  without SVC file and all required setting for WCF hosting we can defined in web.config file.

The service activation is configuration element that allows you to define virtual service activation settings that map to your Windows Communication Foundation (WCF) service types. This makes it possible to activate services hosted in WAS/IIS without a .svc file.

    <serviceHostingEnvironment aspNetCompatibilityEnabled="true" multipleSiteBindingsEnabled="true" >
      <serviceActivations>        <add relativeAddress ="MoneyTransfer.svc" service ="Money.MoneyTransfer"/>

Breakdown the serviceActivations configuration element

·         RelativeAddress : the relative address within the current IIS application and it contain .SVC file address, which does not physically exist

·         Service: the service type that implements the service.

Monday, November 6, 2017

Entity Framework : Eager Loading of Multiple Levels of Entities by Using Include

This blog will demonstrates how to do multiple levels of entities loading by using include() method in entity framework and there are two ways to load the related entities data
  1.       Eagerly Loading
  2.       Lazy Loading

Eagerly Loading : 
In eager loading process, the query related to other related entities is part of the main query and it will be achieved by using INCLUDE method.

Example :

List<Customer> customers = _db.Customers.Include("Addresses").ToList();


List<CustomerData> customers = _db.Customers.Include(c => c.Addresses).ToList();

as you can see in above ef query, Customer entities will be loaded along with included thier assciated Addresses entity data

in below exmaple you can see the multiple level of entities is being loaded. Customer enetity is being loaded with included entities Addresses, Order and it's releated Review entities.

Example :

List<Customer> customers = _db.Customers. Include("Addresses").Include("Orders.Reviews").ToList();

Lazy Loading:
In lazy loading process, the related entities is automatically loaded from the database the first time that property is being referenced or used

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Thursday, November 2, 2017

C# LINQ : SingleOrDefault() Vs. FirstOrDefault()

LINQ provides the operators like Single (), SingleOrDefault(), First() and FirstOrDefault(), they select a specific record from collection.SingleOrDefault() and FirstDefault() returns NULL or Default Value if there is no matching record found.

here is a list of customers :
 List<Customer>Customers = new List<Customer>
                 new Customer { CustomerID = 1, Name= “Herry” },
                 new Customer { CustomerID = 2, Name=”Tom” }

Select record by using FirstOrDefault() method
  Customer customer = Customers.FirstOrDefault(x => x.CustomerID = 1)

Select record by using SingleOrDefault() method
                Customer customer = Customers.SingleOrDefault(x => x.CustomerID = 2);

SingleOrDefault() vs FirstOrDefault()
  • SingleOrDefault() throw exception if we have more than one matching records, and FirstOrDefault() returns the first matching record in sequence.
  • Both SingleOrDefault() and  FirstOrDefault() return default value or NULL, If no matching record found.
  • FirstOrDefault() generates the TSQL statement "SELECT TOP 1..." and SelectOrDefault() generates regular TSQL statement "SELECT ..”
  • In Performance, FirstOrDefault() is usually faster than SingleOrDefault(). The FirstOrDefault() doesn’t care about record uniqueness and amount of record

Recommendations: if you sure, the query should result in at most a single result, you should use SingleOrDefault(), and on other side if query return any number of results, you should use FirstOrDefault() method.

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SQL Server - Identify unused indexes

 In this blog, we learn about the index usage information (SYS.DM_DB_INDEX_USAGE_STATS) and analyze the index usage data (USER_SEEKS, USER_S...