Interview

Web API Routing

2013-11-22T04:38:00.002-08:00

The diagram below tries do describe the decision process behind selecting the method of the controller that will get executed. I've added a little extra documentation through the annotations on the diagram.

1 Action Based
If the route defines the action parameter then the method selection will be based on the value of that parameter. The matching will be based on the method name or the method alias (A method in the controller may be aliased using the ActionName attribute).
All the matching methods are then filtered by verb. The filtering is done by attributes applied to the method (such as HttpGet). Only the methods that match the verb of the incoming request will be returned. Methods with no attributes will also be considered valid as they don’t have any attributes to allow filtration.

2 Verb Based
When the method selection is verb based we need to get the Http verb used in the request. The controller methods are then filtered in two ways:

Get all the methods annotated with http verb attributes matching the http method in the request (attributes such as HttpGet or HttpPost);
Get all the methods that have the prefix matching the http method in the request (PostBooks matches the Post verb);
3 Check Results Found
All the candidate methods returned by either the verb based or action based approach are then analyzed. If no candidates where found an exception is thrown. If multiple methods were found it’s necessary to analyze it’s parameters to find out the best possible fit.

4 Find Route by Parameters
The parameters from the route and the parameters from the query string are compared to the method's parameters. If no parameters are found in the query string or in the route, all methods without parameters will be selected. If multiple methods match the parameters found, the ones that take the most parameters will win. Here is a diagram that details this specific part of the process:

5 Selection Filters
The last filters executed on the candidate methods will make sure that all methods marked with the NonAction attribute will be excluded.

I hope these diagrams were clear enough to help understand better the process of selecting the controller method that gets executed for a request.

Orginal post : http://perezgb.com/2012/03/08/web-api-routing-in-depth

Finalize, Dispose and Unmanaged Resources

2012-01-20T04:36:00.000-08:00

There may be situations where some class has control over resources that are not managed by the runtime such as window handles, database connections, etc. and these resources need to be released as they occupy more memory or affect performance. It can be done explicitly by calling Dispose () to release these objects immediately when they are no more needed. Similarly these objects can also be released implicitly by implementing Finalize() so that they get collected by GC in case someone forgets to call dispose () on these objects. Also since calling Finalize impacts the performance, calls to Finalize can be prevented by invoking the GC.SuppressFinalize method but it should be made sure that it only gets called after Dispose method has completed successfully.

Public class Base:IDisposable
{
Private bool disposed = false;
//Implement IDisposable.
Public void Dispose()
{
Dispose(true);
GC.SuppressFinalize(this);
}

Protected virtual void Dispose(bool disposing)
{
if (!disposed)
{
if (disposing)
{
// Free managed objects.
}
// Free unmanaged objects.
disposed = true;
}
}
// using destructor for finalization.
~Base()
{
Dispose (false);
}
}

Public class Derived: Base
{
Private bool disposed = false;
Protected override void Dispose(bool disposing)
{
if (!disposed)
{
if (disposing)
{
// Release managed resources.
}
// Release unmanaged resources
disposed = true;
}
base.Dispose(disposing);
}
}

Public class Test
{
Public static void Main()
{
//Scenario#1
// Dispose is not called; Finalize will be called
Derived a1 = new Derived();
. . . . . . . .

//Scenario#2
//Dispose is implicitly called in the scope of the using statement.
using (Derived a2 = new Derived())
{
. . . . . . . .
}

//Scenario #3
// Dispose is explicitly called.
Derived a3 = new Derived();
. . . . . . . .
a3.Dispose();
}
}

In the above example, object a2 and a3 are released by calling Dispose method of the base class as a result of which the overloaded dispose method of the derived class and then the base class dispose method gets called to release the managed and unmanaged resources .It can be also noted that the call to finalize() has been suppressed at the end of dispose. In case of object a1, since dispose() method is not called explicitly, finalize method gets called by GC which in turn calls the dispose method of derived class where the unmanaged resources gets released

Task Parallel Library

2012-01-20T03:50:00.000-08:00

Problem: One of the clients was running the multi threaded application on a single core machine, he upgraded his system to Quadra-core and he observed that the application did not improve or started degrading the performance. The development team later found the reason that applications were not utilizing the benefits of cores and it was still running in single core. Solution: .Net 4.0 has brought a new Task Parallel library which uses the benefits of multi core. The Library efficiently utilizes the system resources to give better performance. Internally it uses Threadpool with improved algorithm with .Net 4.0

Namespace: System.Threading.
Tasks Class - Task

Create Task
Task t1 = new Task(() => Add(1,100));
t1.Start();
t1.Wait(); //Wait till task t1 is completed and then starts t2 Task
t2 = new Task(() => Add(101, 200));
t2.Start();

//Other way of creating multiple task
var tasks = new Task[2];
tasks[0] = Task.Factory.StartNew(() => Add(1, 100));
tasks[1] = Task.Factory.StartNew(() => Add(101, 200));
Task.WaitAll(tasks);

Create Dependency of Task
//Add and then display no’s and see output without creating Dependency
var tasks1 = new Task[4];
tasks1[0] =Task.Factory.StartNew(() => Add(1, 50));
tasks1[1] =Task.Factory.StartNew(() => Add(101, 150));
tasks1[2] =Task.Factory.StartNew(() => Display());
tasks1[3] =Task.Factory.StartNew(() => Display());

//Add and then display no’s and create dependency for sequential display
var tasks1 = new Task[4];
tasks1[0] =Task.Factory.StartNew(() => Add(1, 50));
tasks1[1] =Task.Factory.StartNew(() => Add(101, 150));
// start after completing adding of tasks1
tasks1[2] =tasks1[0].ContinueWith((t) => Display());
// start after completing tasks1[2]
tasks1[3] =tasks1[2].ContinueWith((t) => Display());

Cancel Running Task
For Cancelling a task following steps need to be performed:

1. Create Method with input parameter of Cancellation token and check for IsCancellationRequested Property of token to display the message that task is cancelled

public static void CancelProcess(CancellationToken ct)
{
Thread.Sleep(1000);
if (ct.IsCancellationRequested)
{
Console.WriteLine("Process cancelled");
}
}

2. Create token:

var source = new CancellationTokenSource();
var token = source.Token;

3. Create task and call the CancelProcess method, also pass the token to the method
var taskCancel = Task.Factory.StartNew(() => CancelProcess(token), token);

4. Cancel the token source on User's request:
source.Cancel();

The Dynamic Primitive Type in C#

2012-01-20T03:38:00.000-08:00

Runtime type identification made easy! Read on how new ‘dynamic’ type helps.

Let us look at the problems in versions prior to 4.0. A lot of times, we create programs that act on information unaware of its type until at runtime. A type-safe programming language like C# works with runtime-determined information during reflection and has to work a lot with strings which looks clumsy and cause performance problems as shown in the below example.

class Program
{
public class MyType
{
public string MyProperty { get; set; }
}
static void Main(string[] args)
{
var myType = new MyType();
var property = typeof(MyTestType).GetProperty("MyProperty");
property.SetValue(myType, "Hello World", null);
}
}

This is just a simple example which merely sets a property value of a type. Imagine how complex it would be and how clumsy your program would look if you have to Get \ Set ten different property values and then call ten other methods to perform various operations!!! It is no less than a nightmare to code and will have performance problems on top of it.

How C# 4.0 helps here:
C# 4.0 brings in a cool new feature in the form of dynamic keyword which makes programmers life easy while working with runtime-determined information as in reflection. The C# compiler offers you a way to mark an expression’s type as dynamic. You can also put the result of an expression into a variable and you can mark a variable’s type as dynamic. This dynamic expression/variable can then be used to invoke a member such as a field, a property/indexer, a method, delegate, and unary/binary/conversion operators.

When your Code invokes a member using a dynamic expression/variable, the compiler generates special IL code that describes the desired operation. This special code is referred to as the payload.

At runtime, the payload code determines the exact operation to execute based on the actual type of the object now referenced by the dynamic expression/variable. Let’s try this on the same sample shown before and see how it makes life better.

class Program
{
public class MyType
{
public string MyProperty { get; set; }
}
static void Main(string[] args)
{
dynamic myType = new MyType();
myType.MyProperty = "Hello World";
}
}

Isn’t it cool? Any expression can implicitly be cast to dynamic since all expressions result in a type that is derived from Object. Normally, the compiler does not allow you to write code that implicitly casts an expression from Object to another type; you must use explicit cast syntax. However, the compiler does allow you to cast an expression from dynamic to another type using implicit cast syntax:

Object o1 = 123; //OK:Imp cast
Int32 n1 = o1; //Err:No imp cast
Int32 n2 = (Int32)o1; //OK:Exp cast
dynamic d1 = 123; //OK:Imp cast
Int32 n3 = d1; //OK:Imp cast

The CLR will validate the cast at runtime to ensure that type safety is maintained. If the object’s type is not compatible with the cast, the CLR will throw an InvalidCastException exception. Sounds interesting? To know more, please refer to the following links: http://msdn.microsoft.com/en-us/magazine/ee336309.aspx http://msdn.microsoft.com/en-us/library/dd264736.aspx

Windows Server AppFabric Installation and Configuration

2012-01-20T03:18:00.000-08:00

Preparing Your Computer for Installation

• Operating System Windows 7, Windows Server 2003 R2 Standard
• Visual Studio 2010 Ultimate
• Team Foundation Server
• MS SQL Server 2008 R2
• Internet Information Services (IIS) 7.5 with Hotfix #980423
• Microsoft .Net Framework 4.0
• Download the Windows Server AppFabric 6.1 @ http://www.microsoft.com/download/en/details.aspx?displaylang=en&id=15848
• Recommended update for AppFabric at http://msdn.microsoft.com/en-us / windowsserver/ff637504.aspx.

Install Critical Windows Updates
Before installing Windows Server AppFabric or its prerequisites, use the following procedures to install the latest critical Microsoft updates for your version of Windows, and any available recommended update.

Versions of Windows supported in this release are Windows 7, Windows Server 2008 Service Pack 2, and Windows Server 2008 R2. For production scenarios, only Windows Server 2008 SP2 and Windows Server 2008 R2 are supported. For development scenarios, Windows 7 and Windows Vista SP2 are also supported.

• Install Windows Updates
• Click Start, point to All Programs, and then click Windows Update.
• Follow the directions on the Windows Update site.
• If prompted, restart your computer.
• Install Hotfixes

Important
For the latest list of recommended updates for Windows Server AppFabric and its dependencies, see Recommended Updates for Windows Server AppFabric (http://go.microsoft.com/fwlink/?LinkID=185864).

KB980423
You must install KB980423 to fix a set of AppFabric issues caused by Microsoft Web Administration (MWA). After you install this item, you may have to restart your computer.

• KB980423 (http://go.microsoft.com/fwlink/?LinkID=185864)

Note
KB980423 includes KB970773, which is a critical update for IIS Manager in IIS 7.0.
1. Install Windows Server AppFabric

Use the following procedure to install Windows Server AppFabric. You can use the procedures in this topic whether you are starting installation for the first time or adding or removing features after an initial installation. The installation program provides the following functionality:

• Enables you to select specific features to install.
• Validates the platform to ensure that the product is not installed in an unsupported state, and indicates which prerequisites need to be installed.
• Installs AppFabric.
• Enables you to remove specific AppFabric features or AppFabric as a whole, ensuring that the computer can be left in a state in which the features or AppFabric can be reinstalled.
• Creates the AppFabric Event Collector service, the AppFabric Workflow Management service, and the AppFabric Caching Service. Sets the services to a startup type of manual and a status of stopped. In the configuration process, the Event Collector and Workflow Management services are changed to an automatic startup type and are started. The startup type for the Caching Service remains set to manual.

The AppFabric setup program sets configuration settings in the root (server level) Web.config file, the machine.config file, and the applicationHost.config file.
For information about configuration, see Configure Windows Server AppFabric. You can configure AppFabric either immediately after installation, or in a separate process.

To open the installation wizard

1. Open the installation wizard for initial installation by downloading and running the appropriate setup program from Windows Server AppFabric (http://go.microsoft.com/fwlink/?LinkID=183123), as shown in the following table.

These programs all run a Microsoft Update package to install AppFabric features, which are features of Windows.

Platform	Setup package
Windows Vista and Windows Server 2008 x64	WindowsServerAppFabricSetup_x64_6.0.exe
Windows 7 and Windows Server 2008 R2 x64	WindowsServerAppFabricSetup_x64_6.1.exe
Windows Vista and Windows Server 2008 x86	WindowsServerAppFabricSetup_x86_6.0.exe
Windows 7 x86	WindowsServerAppFabricSetup_x86_6.1.exe

2. Proceed to the next section of this topic to install AppFabric

To install AppFabric

1. On the Accept License Terms page, read the license terms, and then accept the terms and click Next to continue, or do not accept the terms and then exit the setup wizard.

2. On the Customer Experience Improvement Program page, select Yes to participate in the Customer Experience Improvement program, or No not to participate, and then click Next. Click the Yes, download and install critical updates. button to install the latest critical updates for Windows Server AppFabric as part of the AppFabric setup experience.

3. On the Feature Selection page, select Hosting Services, Caching Services, Cache Client, Hosting Administration and Cache Administration components then click Next.

4. On the Platform Validation page, review the information and download any necessary prerequisite software. Click the link for a component or a configuration issue for more information. After installing components and/or resolving issues, click Refresh to verify that the problem has been fixed and then click Next to continue with the setup wizard. For more information, see Preparing Your Computer for Installation.

5. The Confirm Installation Selections page will display a list of the features that were selected in the Feature Selection page, and will be installed. It displays a list of the required Windows components and the AppFabric features that will be installed. Verify that the lists are correct, and then click Install to begin installation.

Note

The Application Server role is required for AppFabric. This role will be included in the list of the required Windows components even if it is already installed, and the installation wizard will verify that it has been installed.

6. On the Installation Progress page, you can monitor the progress of the installation.

7. On the Installation Results page, verify that the installation has succeeded.

To display a list of recommended updates that you can install, click the Recommended Updates link. To run the configuration wizard, select the Launch configuration tool check box, and then click Finish to complete the installation wizard. Click Detailed Installation report to display a log of setup events.

Start Configuration of Windows Server AppFabric

1. Open the AppFabric Configuration Wizard after performing the AppFabric Setup Wizard by selecting the Launch configuration tool check box on the Installation Results page of the setup wizard, and then clicking Finish to complete the setup wizard.

2. You can also open the configuration wizard by clicking Start, clicking All Programs, clicking Windows Server AppFabric, and then clicking Configure AppFabric.

3. On the Before You Begin page, select Yes to participate in the Customer Experience Improvement program, or No not to participate, and then click Next. The Configure Hosting Services page will be displayed. Proceed to the next section of this topic.

Configure Monitoring

On the Configure Hosting Services page, use the tables below to configure monitoring, and then click Next.

Note

If Hosting Administration is installed, but Hosting Services is not installed, then the services for the AppFabric Event Collection service and the Workflow Management service are not installed, and the text boxes for the identities of the services will display “Service not installed”.

Control	Description
Set monitoring configuration	Select to select the Event Collection service account, and to select and configure the monitoring store.
AppFabric Event Collection service account	Displays the Windows logon account for the Event Collection service. By default, the Event Collection service account is used for the monitoring provider. The Event Collection service account is a member of the Administrators group, and has administrative access to the monitoring database. The default is NT Authority\LocalService.
Change	If you click Change for the Event Collection service account, you will be able to select the user credential for system services. You can select a built-in account or enter a custom user name and password. In the Select User dialog box, select the account that you want to use for the service, and then click OK. Doing so will update the identity (if it was changed) and restart the service. For more information, see the section Security Model for Windows Server AppFabric in (http://go.microsoft.com/fwlink/?LinkId=193179).
Monitoring provider	Select the provider that will give access to the monitoring database. All valid data providers registered in the local machine.config file will be displayed in this list.
Configure	After selecting the monitoring provider, click to set the configuration for the monitoring provider. For more information about configuring the SQL monitoring provider, see the discussion of the Configure SQL Monitoring Store dialog box below. You can also select a custom monitoring provider.
How to install additional Monitoring providers	You can add a monitoring provider to the list of providers that you can select in the Monitoring provider drop-down box. Click this link to get help on how to add a provider.

If you clicked Configure for the SQL monitoring provider (System.Data.SqlClient) on the Configure Hosting Services page, the Configure SQL Monitoring Store dialog box will be displayed. The following table describes the controls in this dialog box. Use this table to configure the monitoring store, and then click OK to return to the Configure Hosting Services page. Verify that the store was initialized and registered successfully

Control	Description
Register AppFabric monitoring store in root web.config	Select to register the monitoring store identified by the connection string, by adding its configuration to the root Web.config file. This includes the ApplicationServerMonitoringConnectionString and its related monitoring behavior. This registration makes the connection string and behavior available at all scopes on the computer. You can select this check box even if Initialize monitoring store is not selected. Do so if the “AppFabricMonitoringStore” database is already created and initialized, or to point to the database even if it is not initialized. Note This check box is disabled if the Hosting Administration tools are installed, but the Hosting Services feature is not installed.
Initialize monitoring store	Select to initialize the monitoring database “AppFabricMonitoringStore” identified in the connection string, as required before it can be used. Initialization creates the “AppFabricMonitoringStore” database schema and the structure based upon that schema. If the database does not exist, it will be created, and then initialized. If this check box is selected, but Register AppFabric monitoring store in root web.config is not selected, then the database will be created, if necessary, and initialized, but it will not be available for use from this computer. The initializing operation is performed by the initialization cmdlets. For more information, see the Windows Server AppFabric help (http://go.microsoft.com/fwlink/?LinkId=164929). Note For the database to be created, you must have permissions to create databases on the destination server.
Connection string	String specifying the server and database used to access the monitoring store. In the Server field, enter the name of the computer that the database is on. In the Database field, enter the name of the database to be created for monitoring data, or select an existing database from the list.
Security Configuration	Select Windows authentication or SQL Server authentication. For Windows authentication, to change the administrators, readers, or writers’ role, click Browse and use the standard Select User or Group dialog box to enter a different value. You can change the value for administrators, readers, or writers only if Initialize monitoring store is selected. Note When you have installed only Hosting Administration, and you are initializing the monitoring SQL store with Windows authentication, no group or user is entered by default for the Administrators, Readers, or Users role. You will need to click Browse and enter a group or user manually for each role before proceeding with the configuration.

After setting the monitoring configuration, proceed to the next section of this topic if you want to set persistence configuration. Otherwise, click Next to display the Configure Caching Service page, and proceed to the “Configure Caching Service” section of this topic.

Configure Caching Service

On the Configure Caching Service page, use the tables below to configure the Caching Service, and then click Next. A pop-up message will be displayed indicating that this action will apply the Caching Service configuration. To continue, click Yes. When you do so, the configuration settings will be made in the Caching Service configuration file. The Configure Cache Node page will then be displayed.

Note

This page will be displayed only if you selected at least one of the Caching Services features on the Feature Selection page of the installation wizard (Caching Service, Cache Client, or Cache Administration).

Control	Description
Set Caching Service configuration	Select to add or update system-level configuration of the Caching Service feature.
Caching Service account	Displays the Windows logon account for the Caching Service. By default, the Caching Service account is used for the Caching Service configuration provider. The default is NT AUTHORITY\NETWORK SERVICE. Change this account from NT Authority \NETWORK SERVICE to NT Authority\LocalSystem. If your computer is part of a workgroup, you must change the Caching Service account. Use a local account that exists on all computers participating in the cluster and use the same password for the account on all computers. For configuration, the local account must have local administrator privileges, and must not be a built-in account. This step is not necessary for domain-joined machines.
Change	Click to display the Select User dialog box that you use to select an account for the Caching Service account. For more information, see the section Security Model for Windows Server AppFabric in (http://go.microsoft.com/fwlink/?LinkId=193179).
Caching Service configuration provider	When specifying the Caching Service configuration provider, there are two options available: a. XML – Caching Service configuration information is stored in an XML file on a network file share. b. SQL Server Distributed Cache Configuration Store Provider – Caching Service configuration information is stored in a SQL Server database. Warning If XML is selected and the network discovery property is turned off, and you click Browse to select a file share for the XML provider, you will not be able to expand the Network folder in the Browse for Folder dialog box. You can, however, type in a UNC server share. To be able to expand the Network folder, you need to turn network discovery on by opening Control Panel, selecting Network and Internet, selecting Network and Sharing Center, selecting Change Advanced sharing settings, clicking Turn on network discovery, and then clicking Save changes. Note In workgroup scenarios, only the XML provider is supported, not database providers.
Configure	If you chose SQL Server AppFabric Caching Service Configuration Store Provider as the configuration provider, click Configure to create or select a Caching Service configuration database.
File Share	If you chose XML Provider as the configuration provider, enter or browse to the network file share that will contain the XML configuration file. The file share must be a valid UNC path, for example, \\server\share. Important You must manually create a network file share that is accessible to all cache servers in the cache cluster. The user account that is running the AppFabric configuration wizard must have “Owner” or “Co-Owner” permissions to the specified network file share and “Full Control” permissions to the folder at the file system level. The Caching Service must have Read/Write access to the network file share.
Browse	If you click Browse for the File share, you will be able to use the Browse for Folder dialog box to select the file share for the XML configuration provider. Select an existing folder or create a new folder, and then click OK.
New cluster/Join cluster	Select New Cluster if this is the first computer in the cluster. When you run Setup on subsequent computers in the cluster, select Join Cluster. The default is New Cluster. To create or join a cluster, you need to specify the location of the configuration data (either in a database or an XML file), and then on the next page (the Configure AppFabric Cache Node page) enter the ports, and set the firewall settings to unblock the services listed. When creating a cluster, you need to indicate the cluster size (the number of computers in the cluster). This enables the system to optimize memory allocation.
Cluster size	Select one of the following three options to optimize performance based on cluster size. This setting is available only if the New Cluster control is selected. · Small [1-5 computers] · Medium [6-15 computers] · Large [> 15 computers] Note After this selection has been set, it cannot be changed. Note Your cluster size is not limited by this selection. You can still add or remove computers from the cluster after optimization. However, performance will only be optimized when the cluster size is within the range specified. Select a cluster size based upon the eventual number of nodes that will be in the cluster. After you set the cluster size during configuration, you cannot change it later. If you select Small for the cluster size, the cluster will be optimized for one to five computers. If your cluster eventually grows to ten computers, the cluster will still be optimized for one to five computers. You cannot subsequently change the cluster size to Medium, in order to optimize the cluster for 6 to 15 computers.

If you selected SQL Server AppFabric Caching Service Configuration Store Provider in the Caching Service configuration provider drop-down list and click Configure, the Windows Server AppFabric Caching Configuration Store dialog box will be displayed. Use the tables below to configure the SQL store, and then click Next.

Note

When you click OK in the Windows Server AppFabric Caching Configuration Store dialog box, the distributed cache database will be created, and a pop-up message with the results of the operation will be displayed.

Note

Security configuration settings do not need to be made on this page because Windows authentication is required. Caching does not support SQL authentication.

Control	Description
Register AppFabric Caching Service configuration database	Select “AppFabricCachingStore” to register the configuration database identified by the connection string, by adding its configuration to the root Web.config file, and to set the security configuration. This registration makes the connection string and behavior available at all scopes on the computer. You can select this check box even if Create AppFabric Caching Service configuration database is not selected. Do so if the database is already created.
Create AppFabric Caching Service configuration database	Select to create the configuration database and to specify the connection string. Give a database name as “AppFabricCachingStore”.
Connection String	Enter the server in the Server field and select or type the database in the Database field.

When you click Next with the Configure Caching Service page displayed, the Configure AppFabric Cache Node page will be displayed. Use the tables below to configure the cache node ports and Windows firewall.

Note
This page will be displayed only if you selected at least one of the Caching Services features on the Feature Selection page. You can set the firewall exceptions only if the Windows Firewall service is enabled.

Note
If the Windows Firewall is disabled, the Windows firewall exceptions area of the Configure AppFabric Cache Node dialog box will be disabled.

Control	Description
Node ports	Enter or select a unique value for each port, or leave the default settings. · Service port. The default is 22233. · Cluster port. The default is 22234. · Arbitrator port. The default is 22235. · Replication port. The default is 22236. The valid range for port values is 1024 through 65535. Each port must have a unique port number.
Windows firewall exceptions	For the AppFabric Distributed Cache features to function, you must configure the Windows Firewall rules to allow access for the Cache Service. a. Windows Server AppFabric: AppFabric Caching Service b. Remote Service Management Important If you are using a third party (non-Windows) firewall, or a Windows Firewall that is subject to domain policy, you must manually configure the firewall for the caching features to work properly.

Note
After you click Next on the Configure AppFabric Cache Node page, the Configure Application page will be displayed if the AppFabric hosting features are installed.

Complete Configuration of Windows Server AppFabric
On the Configure Application page, select Start Internet Information Services (IIS) Manager to configure an application in the IIS Manager. Click Finish to close the configuration wizard.

Note
After the AppFabric Configuration Wizard has successfully configured the Caching Service, you will need to use administration cmdlets to start the cluster or start individual hosts in the cluster. Use the Start-CacheCluster or Start-CacheHost cmdlet. For more information about these cmdlets, see Cache Administration with Windows PowerShell (http://go.microsoft.com/fwlink/?LinkId=193181).

Start Cache Host Services for the First Time

After installation for the first time, you will need to start the cache cluster. Configure at least one node in the cluster, and then execute a cmdlet to start the cluster.

In the developer scenario (using a single-node cluster), to start a new cluster execute Use-CacheCluster (to set the context of your Windows PowerShell session to a particular cache cluster) and then execute Start-CacheCluster.

In a multiple-node cluster, to start all cache host services in the cluster (lead hosts first), execute Start-CacheCluster. For additional cache hosts (and any other cluster-level configuration changes) to be acknowledged by the cache cluster, you need to restart all cache host services with Restart-CacheCluster. To start a specific cache host service, execute Start-CacheHost.

For more information, see Cache Administration with Windows PowerShell (http://go.microsoft.com/fwlink/?LinkId=193181).

Create AppFabric Cache

To create the AppFabric Cache follow the below steps:

a. Open the Power Shell by clicking Start, clicking All Programs, clicking Windows Server AppFabric, and then clicking Caching Administration Windows PowerShell.

b. Run the following command to create the cache.

c. get-command -module DistributedCacheAdministration

d. Start-CacheCluster

e. New-Cache -CacheName [CacheName]–Expirable false

f. Restart-CacheCluster

g. Get-CacheStatistics [CacheName]

h. Get-Cache

Host a Services in AppFabric and Configure the IIS with AppFabric

To configure the IIS with AppFabric follow the below steps:

1. Open the IIS Manager to configure the AppFabric

2. Right click on Default Web Site, click on Manage WCF and WF Services and then Select Configure as shown in Figure 9.1.1.

Figure 9.1.1

Now Click on Monitoring from Configure WCF and WF for Site Window as shown below in Figure 9.1.2.

Figure 9.1.2

Check the Check box “Write events to database”, Select the appropriate Connection string for AppFabric Monitoring database, set the Level to “End to End Monitoring” and then click on Apply button as shown in Figure 9.1.3.

Figure. 9.1.3.

Finally, click on Ok button to close the windows.

Now, your IIS is configured with the AppFabric Monitoring.

To configure the service with AppFabric follow the below steps:

Open the IIS Manager to configure the AppFabric
Right click on Discovery, click on Manage WCF and WF Services and then Select Configure as shown in Figure 9.2.1.

Figure. 9.2.1

Now Click on Monitoring from Configure WCF and WF for Site Window as shown in Figure 9.2.2.

Figure. 9.2.2

Check the Check box “Write events to database”, Select the appropriate Connection string for AppFabric Monitoring database, set the Level to “End to End Monitoring” and then click on Apply button as shown in Figure 9.2.3.

Figure. 9.2.3

Now select Auto-Start tab to enable the Auto-Start option as shown in Figure 9.2.4.

Figure. 9.2.4

Finally, click on Ok button to close the windows.

Note: Repeat the same steps mentioned in section 9.2 for all the other Service to configure the AppFabric Monitoring.

Explore Kaazing Websocket in .Net

2012-01-20T01:28:00.000-08:00

Introduction

Kaazing WebSocket Gateway provides full duplex web communication. It provides an alternate way of communication from server to client for “polling” or “long-polling”.

WebSocket

WebSocket is a full-duplex single socket connection over which messages can be sent between a client and a server. The WebSocket standard simplifies much of the complexity around bi-directional web communication and connection management.

Kaazing WebSocket

Kaazing WebSocket Gateway is an HTML5-compliant WebSocket server with support to today's pre-HTML5 browsers. The Gateway provides a bridge between WebSocket clients and your back-end systems, servers, and applications. This enables you to implement your own custom protocol or run an existing protocol over WebSocket.

Installing Kaazing WebSocket

1. Kaazing WebSocket can be installed in Windows 7, Windows Vista, Windows XP SP3

2. Download the full Kaazing WebSocket Gateway - HTML5 Edition from the Kaazing download page.

3. There are two type of download available

a. Base: Contains a minimal download of the Gateway for experienced users who are ready to use the Gateway in production.

b. Full: Contains the Base download plus the Gateway documentation and the services needed to run the Gateway demos.

4. Unpack the Kaazing WebSocket Gateway distribution into a directory of your choice (for example, C:\kaazing or /home/username/Kaazing). Unpacking the distribution creates a directory containing the Gateway; this directory is referred to as GATEWAY_HOME in the documentation.

5. On Windows you can use an Unzip program to unpack the Gateway *.zip file

6. Start the demo services by navigating to the GATEWAY_HOME/bin directory and running the demo-services.start.bat (Windows) script.

a. To start the demo service in Windows Explorer, navigate to the GATEWAY_HOME/bin directory where you installed the Gateway

b. Use the following command to start the demo services, and substitute either the public IP address or the public DNS name for example.com:
demo-services.start.bat udp://example.com:50505

7. Start Kaazing WebSocket Gateway by navigating to the GATEWAY_HOME/bin directory and running the gateway.start.bat (Windows) script.

a. To start the gateway on Windows ; In Windows Explorer, navigate to the GATEWAY_HOME/bin directory where you installed the Gateway.

b. Double-click the gateway.start.bat script.

8. Verify the Gateway setup by navigating to http://localhost:8001/ in your browser.

9. Verify Gateway

a. To verify that the Gateway is up and running, open a browser and access the Gateway home page at http://localhost:8001/. Click the Documentation tab to see the documentation library and learn more about the Gateway. Click the Demos tab to view the demos.

b. A WebSocket Echo demo service is bundled and started by default in the Full product. If you want to configure your own back-end service, see the Advanced configuration service and the client how-to guides on the Kaazing Documentation home page for more information.

c. See the Release Notes (online only) for an overview of the certified browser versions for this release.

You are now done setting up Kaazing WebSocket Gateway locally.

Note:

When running the com.kaazing.gateway.client.dotnet.core.demo.exe demo for dotnet from GATEWAY_HOME/ demo/dotnet/bin/Release then exception is thrown as “Cannot load the System.Net assembly”.

In order to resolve this error you have to download .NET Framework 4 update from this url http://www.microsoft.com/download/en/details.aspx?displaylang=en&id=3556.

Configuring Kaazing WebSocket Gateway to use Multicast

To Multicast we have to specify the multicast URI (an IP address with the multicast address mask of 224.0.0.0) in the accept property.

The following is an example of a service configuration element in the file GATEWAY_HOME/conf/gateway-config.xml for a service using a multicast address. In this example, data packets sent to the multicast group 224.0.0.1:50505 (shown in line 8) will be broadcast to all clients connected to sse://localhost:8000/sse or sse+ssl://localhost:9000/sse.

To verify this configuration, you can start the newsfeed data source that ships with the Kaazing WebSocket Gateway bundle and pass the multicast URI you have configured as a startup argument. To do this, perform the following steps:

In a command prompt or shell, navigate to GATEWAY_HOME/bin.

Run gateway.demos.start mcp://multicast-uri:port-number (for example, gateway.demos.start mcp://224.0.0.1:50505) to start the newsfeed data source.

Run gateway.start to start the Gateway.

In a browser, navigate to the server-sent events demo page (by default, this is located at http://localhost:8001/demo/sse.html) and watch the streaming news feed data.

You can now configure and run a second Kaazing WebSocket Gateway to serve server-sent event streams from a different host and port for the same newsfeed multicast data packets. Note that services cannot send UDP packets to an MCP acceptor, nor MCP packets to a UDP acceptor.

After configuring the gateway create .Net console server application and add below listed code in your server application.

private void MultiCastMessage()

{

Console.WriteLine("Start Transmitting the message ");

Console.WriteLine("");

Console.Read();

UdpClient udpClient = new UdpClient();

try

{

string hName = Dns.GetHostName();

var address = Dns.GetHostAddresses(hName);

udpClient.Connect(new IPEndPoint(address[1], 50505));

List<String> messages = new List<string>();

messages.Add("Sending message from Origin(Server).");

Byte[] msgByte = default(Byte[]);

foreach (String msg in messages)

{

Console.WriteLine("Sending Message ......... ");

Console.WriteLine(msg);

System.Threading.Thread.Sleep(1000);

msgByte = Encoding.ASCII.GetBytes(msg);

int i = udpClient.Send(msgByte, msgByte.Length);

System.Threading.Thread.Sleep(3000);

Console.WriteLine("----------------------------------------------");

}

Console.WriteLine("");

Console.WriteLine("Completed Transmitting the message ");

udpClient.Close();

Console.ReadLine();

}

catch (Exception ex)

{

Console.WriteLine("Error : " + ex.Message);

}

In Main method of your console application call method MultiCastMessage()

static void Main(string[] args)

{

MultiCastMessage();

}

Create Windows Form Client application to send and receive messages.

Add Reference to “com.kaazing.gateway.client.html5.dll”
Include in your code as “using com.kaazing.gateway.client.html5;”
Set the default location as String defaultLocation = "http://localhost:8001/sse";

Add HandleLog method to client application

private void HandleLog(String message)

{

this.BeginInvoke((InvokeDelegate)(() =>

{

Log("LOG: " + message);

}));

}

Add “Connect ” button and add code for ConnectButton_Click event

private void ConnectButton_Click(object sender, EventArgs e)

{

// Immediately disable the connect button

ConnectButton.Enabled = false;

eventSource = new EventSource();

Log("CONNECT:" + LocationText.Text);

eventSource.OpenEvent += new OpenEventHandler(OpenHandler);

eventSource.ErrorEvent +=new ErrorEventHandler(ErrorHandler);

eventSource.MessageEvent += new MessageEventHandler(MessageHandler);

eventSource.Connect(LocationText.Text);

}

Add “Disconnect ” button and add code for DisconnectButton_Click event

private void DisconnectButton_Click(object sender, EventArgs e)

{

Log("DISCONNECTED");

eventSource.Disconnect();

ConnectButton.Enabled = true;

}

Add LOG_LIMIT and logLines Variables

private const int LOG_LIMIT = 50;

private Queue<string> logLines = new Queue<string>();

Add Log method

private void Log(string arg)

{

logLines.Enqueue(arg);

if (logLines.Count > LOG_LIMIT)

{

logLines.Dequeue();

}

string[] o = logLines.ToArray<string>();

o = o.Reverse<string>().ToArray<string>();

Output.Text = string.Join("\r\n", o);

}

Add “ClearLogButton ” button and add code for ClearLogButton_Click event

private void ClearLogButton_Click(object sender, EventArgs e)

{

logLines.Clear();

Output.Text = "";

}

Add code for OpenHandler

private void OpenHandler(object sender, OpenEventArgs args)

{

this.BeginInvoke((InvokeDelegate)(() =>

{

Log("CONNECTED");

DisconnectButton.Enabled = true;

}));

}

Add code for MessageHandler

private void MessageHandler(object sender, MessageEventArgs args)

{

string messageData = args.Data;

string origin = args.Origin;

string lastEvent = args.EventId;

this.BeginInvoke((InvokeDelegate)(() =>

{

Output.Text = Output.Text + Environment.NewLine + " Recieved : " +

messageData + Environment.NewLine + "-----";

}));

}

Add code for ErrorHandler

private void ErrorHandler(object sender, ErrorEventArgs args)

{

this.BeginInvoke((InvokeDelegate)(() =>

{

Exception ex = args.GetException;

Output.Text = ex.InnerException.ToString();

}));

}

1. Start Kaazing WebSocket Gateway by navigating to the GATEWAY_HOME/bin directory and running the gateway.start.bat (Windows) script.

2. Start Server application

3. Start Client application

4. In Client App Conncet to Gateway by clicking on “Connect” button.

5. From Client App Send a message from Client App

As you can see in above screen shot client received the message sent from server.

ASP.NET Cache dependency example

2012-01-18T03:52:00.000-08:00

In this article we will learn how to implement file dependency in caching.

In this method the cache["messageDependency"] loads the file "DependencyFile.txt" in memory(cache) only when its content is changed in the disk.

public void displayMessage()

{

String message;

String Path = "~/DependencyFile.txt";

if (Cache["messageDependency"] == null)

{

System.IO.StreamReader sReader = new StreamReader(Server.MapPath(Path));

message = sReader.ReadToEnd();

sReader.Close();

System.Web.Caching.CacheDependency msgDependency = new System.Web.Caching.CacheDependency(Server.MapPath(Path));

Cache.Insert("messageDependency", message, msgDependency);

}

Response.Write(Cache["messageDependency"].ToString());

}

Sending email in SSIS using script task

2012-01-18T03:50:00.001-08:00

Sending mail using script task. We can send email with attachments and also either in text format or in HTML format

Public Sub SendMail(ByVal message As String)
        Dim vars As Variables
        Dim myHtmlMessage As MailMessage
        Dim mySmtpClient As SmtpClient

        myHtmlMessage = New MailMessage()

        Dim FromAddress As String
        Dts.VariableDispenser.LockOneForWrite("from", vars)
        FromAddress = vars("from").Value.ToString().Trim()
        vars.Unlock()

        Dim ToAddress As String
        Dts.VariableDispenser.LockOneForWrite("to", vars)
        ToAddress = vars("to").Value.ToString().Trim()
        vars.Unlock()

        Dim CCAddress As String
        Dts.VariableDispenser.LockOneForWrite("cc", vars)
        CCAddress = vars("cc").Value.ToString().Trim()
        vars.Unlock()

        Dim SmtpClient As String
        Dts.VariableDispenser.LockOneForWrite("smtpServer", vars)
        SmtpClient = vars("smtpServer").Value.ToString().Trim()
        vars.Unlock()

myHtmlMessage.From = New Mail.MailAddress(FromAddress)

        Dim tt As String()
        If (ToAddress.ToString().Trim().Length > 0) Then
            If (ToAddress.IndexOf(";") > 0) Then
                tt = ToAddress.Split(";")
                Dim c As String
                If (tt.Length > 0) Then
                    For Each c In tt
                        myHtmlMessage.To.Add(c)
                    Next
                End If
            Else
                myHtmlMessage.To.Add(ToAddress.ToString().Trim())
            End If
        End If

        Dim cc As String()
        If (CCAddress.ToString().Trim().Length > 0) Then
            If (CCAddress.IndexOf(";") > 0) Then
                cc = CCAddress.Split(";")
                Dim c As String
                If (cc.Length > 0) Then
                    For Each c In cc
                        myHtmlMessage.CC.Add(c)
                    Next
                End If
            Else
                myHtmlMessage.CC.Add(CCAddress)
            End If
        End If

Dim MailSubject As String = " Email scheduling process"
Dim mailBody As String = "Hi, " + message + " Thanks, XXX"

        myHtmlMessage.Subject = MailSubject
        myHtmlMessage.IsBodyHtml = True
        mySmtpClient = New SmtpClient(SmtpClient)
        mySmtpClient.Credentials = CredentialCache.DefaultNetworkCredentials

        mySmtpClient.Send(myHtmlMessage)

    End Sub

How to embed an image in your Email

2012-01-18T03:49:00.000-08:00

In this code we will learn how to embed an image in mail using VB.NET.

Public Sub SendMail(ByVal message As String)
        Dim vars As Variables
        Dim myHtmlMessage As MailMessage
        Dim mySmtpClient As SmtpClient
        Dim retVal As Int32 = -1

myHtmlMessage = New MailMessage()

        Dim FromAddress As String
        Dts.VariableDispenser.LockOneForWrite("from", vars)
        FromAddress = vars("from").Value.ToString().Trim()
        vars.Unlock()

        Dim ToAddress As String
        Dts.VariableDispenser.LockOneForWrite("to", vars)
        ToAddress = vars("to").Value.ToString().Trim()
        vars.Unlock()

        Dim CCAddress As String
        Dts.VariableDispenser.LockOneForWrite("cc", vars)
        CCAddress = vars("cc").Value.ToString().Trim()
        vars.Unlock()

        Dim SmtpClient As String
        Dts.VariableDispenser.LockOneForWrite("smtpServer", vars)
        SmtpClient = vars("smtpServer").Value.ToString().Trim()
        vars.Unlock()

        myHtmlMessage.From = New Mail.MailAddress(FromAddress)

Dim MailSubject As String = " Email scheduling process"
Dim mailBody As String = "Hi, " + message + " Thanks, XXX"

        Dim ApplicationPath As String ' Physical path of an image. Example: C:/images/
        Dts.VariableDispenser.LockOneForWrite("ApplicationPath", vars)
        ApplicationPath = vars("ApplicationPath").Value.ToString().Trim()
        vars.Unlock()

' EMBEDING IMAGE
 Dim contentId As String = "image1" ' giving ID to an image content
 Dim path As String = ApplicationPath + "\\myLogo.JPG"
 Dim myImage As String = "<img src=""cid:image1""/> "
 Dim mybody As String = String.Empty
 Dim linkedResource As System.Net.Mail.LinkedResource = New System.Net.Mail.LinkedResource(path)
 Dim av1 As System.Net.Mail.AlternateView
 linkedResource.ContentId = contentId
 linkedResource.ContentType.Name = path
 av1 = System.Net.Mail.AlternateView.CreateAlternateViewFromString(mailBody + "" + myImage, Nothing, System.Net.Mime.MediaTypeNames.Text.Html)
 av1.LinkedResources.Add(linkedResource)
 myHtmlMessage.AlternateViews.Add(av1)

 myHtmlMessage.Subject = MailSubject
 myHtmlMessage.IsBodyHtml = True
 mySmtpClient = New SmtpClient(SmtpClient)
 mySmtpClient.Credentials = CredentialCache.DefaultNetworkCredentials

        mySmtpClient.Send(myHtmlMessage)

    End Sub

Handling error while connecting to FTP server using SSIS FTP task

2012-01-18T03:48:00.000-08:00

SSIS FTP task does't allow user to connect to different FTP servers. If we store FTP connection sting (Example: ftp.xxx.com:21.username.password)in Config file also it will accepts domain name, port and username but it wont accept password. Also FTP task has not exposed the FTP password property. To over come this problem we have to override the FTP connection manager itself. So that it accepts connections dynamically.

Public Sub Main()
        Dim vars As Variables

        Dim ftpConnectionManager As ConnectionManager
        ftpConnectionManager = Dts.Connections("FTP Connection Manager")

        ' ADDED TO MAKE FTP CONNECTION STRING DYNAMIC
        Dim FtpServer As String
        Dim FtpPort As String
        Dim FtpUser As String
        Dim FtpPassword As String

        Dts.VariableDispenser.LockOneForWrite("FtpServer", vars)
        FtpServer = Text.Encoding.Unicode.GetString(Convert.FromBase64String(vars("FtpServer").Value.ToString().Trim()))
        vars.Unlock()

'MsgBox("FtpServer = " + FtpServer)

        Dts.VariableDispenser.LockOneForWrite("FtpPort", vars)
        FtpPort = Text.Encoding.Unicode.GetString(Convert.FromBase64String(vars("FtpPort").Value.ToString().Trim())) 'vars("FtpPort").Value.ToString().Trim()
        vars.Unlock()

'MsgBox("FtpPort = " + FtpPort)

        Dts.VariableDispenser.LockOneForWrite("FtpUser", vars)
        FtpUser = Text.Encoding.Unicode.GetString(Convert.FromBase64String(vars("FtpUser").Value.ToString().Trim())) ' vars("FtpUser").Value.ToString().Trim()
        vars.Unlock()

'MsgBox("FtpUser = " + FtpUser)

        Dts.VariableDispenser.LockOneForWrite("FtpPassword", vars)
        FtpPassword = Text.Encoding.Unicode.GetString(Convert.FromBase64String(vars("FtpPassword").Value.ToString().Trim())) ' vars("FtpPassword").Value.ToString().Trim()
        vars.Unlock()

'MsgBox("FtpPassword = " + FtpPassword)

        Dts.Connections("FTP Connection Manager").Properties("ServerName").SetValue(ftpConnectionManager, FtpServer)
        Dts.Connections("FTP Connection Manager").Properties("ServerPort").SetValue(ftpConnectionManager, FtpPort)
        Dts.Connections("FTP Connection Manager").Properties("ServerUserName").SetValue(ftpConnectionManager, FtpUser)
        Dts.Connections("FTP Connection Manager").Properties("ServerPassword").SetValue(ftpConnectionManager, FtpPassword)

Dts.TaskResult = Dts.Results.Success

End Sub

Error handling in SSIS

2012-01-18T03:47:00.000-08:00

In this article we will learn how to handle the errors in SSIS package. In SSIS when package throws an error then these error details is stored in following variables ErrorCode, ErrorDescription and SourceName.

Below is the code to handle error in SSIS package.
When a SSIS task encounters an error these error details are stored in three system variables.
Dts.VariableDispenser.LockForRead("ErrorCode")
Dts.VariableDispenser.LockForRead("ErrorDescription")
Dts.VariableDispenser.LockForRead("SourceName")
ErrorCode variables returns error code which will be numeric.
ErrorDescription will give us a brief description of an error encountered by the SSIS task.
SourceName give us the task name from which error occured.
Private Sub GetErrorValues(ByRef errNumber As Integer, ByRef errDescription As String, ByRef errSource As String)

            Dts.VariableDispenser.LockForRead("ErrorCode")
            Dts.VariableDispenser.LockForRead("ErrorDescription")
            Dts.VariableDispenser.LockForRead("SourceName")
            Dts.VariableDispenser.GetVariables(vars)
            Try
                errNumber = CType(vars("ErrorCode").Value, Integer)
                errDescription = vars("ErrorDescription").Value.ToString()
                errSource = vars("SourceName").Value.ToString()
            Catch ex As Exception
                Throw ex
            Finally
                vars.Unlock()
            End Try
        Catch ex As SystemException
            Throw ex
        End Try
    End Sub

File handling in VB.Net

2012-01-18T03:45:00.000-08:00

Append data to existing file

Here I am using FileStream object to write contents to a file.
First a FileSteam and File object is created. Using file object we will compare wether file is exists are not.
If file exits in the disk then we will truncate it otherwise we will create new file and allow that file for read and write using file steam object.
If file already exists then we will open that file in append mode.
Then we will point the stream reader to last line using streamwriter.
Example : sw.BaseStream.Seek(0, SeekOrigin.End)
If file does't exists then we will create new file and open that file in create mode.
Then we will point the stream reader to first line using streamwriter.
Example: sw.BaseStream.Seek(0, SeekOrigin.Begin)

Public Sub ExportToFile(ByVal oFileName As String, ByVal myContent As String)

        Dim file As FileStream
        Dim f As IO.File

        If (f.Exists(oFileName)) Then
            file = New FileStream(FileToWrite, FileMode.Append, FileAccess.Write)
        Else
            file = New FileStream(FileToWrite, FileMode.Create, FileAccess.ReadWrite)
        End If

        Dim sw As New StreamWriter(file, System.Text.Encoding.Default)
        If (f.Exists(oFileName)) Then
            sw.BaseStream.Seek(0, SeekOrigin.End)
        Else
            sw.BaseStream.Seek(0, SeekOrigin.Begin)
        End If

        sw.Write(myContent)

        sw.Close()

End Sub

To create file and write to it using FileStream

Public Sub WriteErrorReport(ByVal message As String, ByVal FileName As String)

Dim f As File

Dim fstream As FileStream

If f.Exists(FileName) Then

fstream = New FileStream(FileName, FileMode.Truncate, FileAccess.ReadWrite)

Else

fstream = New FileStream(FileName, FileMode.Create, FileAccess.ReadWrite)

End If

Dim sWriter As New StreamWriter(fstream)

sWriter.BaseStream.Seek(0, SeekOrigin.Begin)

sWriter.Write(message)

sWriter.Close()

End Sub

Get the data one by one from a comma separated string using SQL query

2012-01-18T03:40:00.000-08:00

In this article we will see how to separate data one by one from a comma separated string.

First declare a variable to store articles in comma separated values.

DECLARE @DataString VARCHAR(200)
SET @DataString = 'ASP.NET, VB.NET, C#.NET, SQL, Javascript'

Add comma at last to @DataString

SET @DataString = @DataString + ','

Using while loop through all the topics in @DataString

WHILE (CHARINDEX(',', @DataString) > 0)
-- CHARINDEX is a SQL inbuilt function which returns the integer value if charecter is present in a string.
BEGIN
        -- To hold each topic
        DECLARE @Topics VARCHAR(30)
        -- Get the topic one at a time
        SET @Topics = SUBSTRING(@DataString,0, CHARINDEX(',', @DataString))
        PRINT @Topics

        -- Reset the @DataString
        SET @DataString = SUBSTRING(@DataString, CHARINDEX(',', @DataString) + 1, LEN(@DataString))

END

Here is the out put of the above query

ASP.NET
VB.NET
C#.NET
SQL
Javascript

Looping through the rows of a table without using cursor in SQL Server

2012-01-18T03:39:00.000-08:00

In this article we will see ow to loop through the rows of a table without using cursor

In this article I will explain how to loop through each rows in a table and get the data one by one for processing.

-- Create a table variable to store user data
DECLARE @myTable TABLE
(
 UserID INT IDENTITY(1,1),
 UserName VARCHAR(50),
 Password VARCHAR(50),
 Email VARCHAR(50)
)

-- Insert some data to table to work on that data

INSERT INTO @myTable(UserName, Password, Email)
VALUES ('Jack', 'JackPwd', 'jack@gmail.com')

INSERT INTO @myTable(UserName, Password, Email)
VALUES ('Raj', 'RajPwd', 'raj@gmail.com')

INSERT INTO @myTable(UserName, Password, Email)
VALUES ('smith', 'smithPwd', 'smith@gmail.com')

INSERT INTO @myTable(UserName, Password, Email)
VALUES ('Tom', 'tomPwd', 'tom@gmail.com')

-- Get the number of rows in the looping table
DECLARE @RowCount INT
SET @RowCount = (SELECT COUNT(UserID) FROM @myTable)

-- Declare an iterator
DECLARE @I INT
-- Initialize the iterator
SET @I = 1

-- Loop through the rows of a table @myTable
WHILE (@I <= @RowCount)
BEGIN
 -- Declare variables to hold the data which we get after looping each record
 DECLARE @iUserName VARCHAR(50), @iPassword VARCHAR(50), @iEmail VARCHAR(50)

 -- Get the data from table and set to variables
 SELECT @iUserName = UserName, @iPassword = Password, @iEmail = Email FROM @myTable WHERE UserID = @I
 -- Display the looped data
 PRINT 'Row No = ' + CONVERT(VARCHAR(2), @I)
 PRINT 'UserName = ' + @iUserName + ', Password = ' + @iPassword + ' Email = '+ @iEmail
 -- Increment the iterator
 SET @I = @I + 1
END

Here is the output of the above query.

Row No = 1
UserName = Jack, Password = JackPwd Email = jack@gmail.com
Row No = 2
UserName = Raj, Password = RajPwd Email = raj@gmail.com
Row No = 3
UserName = smith, Password = smithPwd Email = smith@gmail.com
Row No = 4
UserName = Tom, Password = tomPwd Email = tom@gmail.com

Implementing sorting in SQL query without using dynamic query

2012-01-18T03:37:00.000-08:00

In this article we will learn how to sort the table values with out using dynamic query to improve performance.

CREATE PROCEDURE SortingExample
(
@sortFiled INT,
@sortType INT -- 1 for ASC, 2 for DESC
)
AS
BEGIN
-- Create a table variable to store user data
DECLARE @myTable TABLE
(
UserID INT IDENTITY(1,1),
UserName VARCHAR(50),
Password VARCHAR(50),
Email VARCHAR(50)
)

-- Insert some data to table to work on that data

INSERT INTO @myTable(UserName, Password, Email)
VALUES ('Jack', 'JackPwd', 'jack@gmail.com')

INSERT INTO @myTable(UserName, Password, Email)
VALUES ('Anand', 'AnandPwd', 'raj@gmail.com')

INSERT INTO @myTable(UserName, Password, Email)
VALUES ('smith', 'smithPwd', 'smith@gmail.com')

INSERT INTO @myTable(UserName, Password, Email)
VALUES ('Brandy', 'BrandyPwd', 'tom@gmail.com')

-- If @sortType = 1 then sort the selected field in ASC order
-- Otherwise sort the selected field in DESC order
IF (@sortType = 1)
BEGIN
SELECT UserID, UserName, Password, Email FROM @myTable ORDER BY
-- To sort numeric field we have to convert int field into varchar field
CASE @sortFiled WHEN 1 THEN RIGHT(('000000000000000000' + CONVERT(VARCHAR(30), UserID)),18)
WHEN 2 THEN UserName
WHEN 3 THEN Password
END ASC
END
ELSE
BEGIN
SELECT UserID, UserName, Password, Email FROM @myTable ORDER BY
CASE @sortFiled WHEN 1 THEN RIGHT(('000000000000000000' + CONVERT(VARCHAR(30), UserID)),18)
-- To sort numeric field we have to convert int field into varchar field
WHEN 2 THEN UserName
WHEN 3 THEN Password
END DESC
END
END

See the pics below for the output of above query.

-- Sorting numeric column (UserID)
EXEC SortingExample 1, 1 -- Sorting UserID column in ASSENDING
EXEC SortingExample 1, 2 -- Sorting UserID column in DESENDING

-- Sorting varchar column(UserName)
EXEC SortingExample 2, 1 -- Sorting UserName column in ASSENDING
EXEC SortingExample 2, 2 -- Sorting UserName column in DESENDING

Converting table rows as columns in SQL server

2012-01-18T03:34:00.000-08:00

In this article we will learn how to convert table rows into columns as comma separated.

-- Create a table variable to store user data
DECLARE @myTable TABLE
(
UserName VARCHAR(50),
ArticleName VARCHAR(50)
)

-- Insert some data to table to work on that data
INSERT INTO @myTable(UserName, ArticleName)
VALUES ('Jack', 'ASP.NET')
INSERT INTO @myTable(UserName, ArticleName)
VALUES ('Jack', 'SQL Server')
INSERT INTO @myTable(UserName, ArticleName)
VALUES ('Jack', 'C#')
INSERT INTO @myTable(UserName, ArticleName)
VALUES ('Jack', 'VB.NET')

INSERT INTO @myTable(UserName, ArticleName)
VALUES ('David', 'Java')
INSERT INTO @myTable(UserName, ArticleName)
VALUES ('David', 'Java Beans')
INSERT INTO @myTable(UserName, ArticleName)
VALUES ('David', 'Java script')

SELECT UserName, ArticleName FROM @myTable

-- This is how the table looks after inserting the data

Now I want all the articles related to Jack and David in a single column.
This how we can achieve this
-- Cross join each user with his article. By cross joining we will get all the articles for each user
SELECT DISTINCT A.UserName,Articles FROM @myTable A
CROSS APPLY
(
-- Now get all the articles for each author in XML
SELECT ArticleName + ', ' FROM @myTable B WHERE A.UserName = B.UserName
FOR XML Path('')
) AS C (Articles)

The output of the below query is shown below.
-- By applying cross join I can able to get all the articles related with Jack and David.

Making SSIS package to accept dynamic oledb connetions

2012-01-18T02:16:00.001-08:00

SSIS oledb connection manager does't allow user to connect to different oledb servers. If we store oledb connection sting in Config file then it will accepts server name, InitialCatalog and username. But it wont accept password. The is because oledb connection manager has not exposed the oledb password property. To over come this problem we have to override the OLEDB connection manager itself. So that it accepts connections to different oledb servers.

Public Sub Main()
Dim vars As Variables

Dim oledbConnectionManager As ConnectionManager
oledbConnectionManager = Dts.Connections("<oledb connection name>")

' ADDED TO MAKE oledb CONNECTION STRING DYNAMIC
Dim oServerName As String
Dim oUserName As String
Dim oInitialCatalog As String
Dim oPassword As String

Dts.VariableDispenser.LockOneForWrite("oServerName", vars)
oServerName = vars("oServerName").Value.ToString().Trim()
vars.Unlock()

Dts.VariableDispenser.LockOneForWrite("oInitialCatalog", vars)
oInitialCatalog = vars("oInitialCatalog").Value.ToString().Trim())
vars.Unlock()

Dts.VariableDispenser.LockOneForWrite("oUserName", vars)
oUserName = vars("oUserName").Value.ToString().Trim())
vars.Unlock()

Dts.VariableDispenser.LockOneForWrite("oPassword", vars)
oPassword = vars("oPassword").Value.ToString().Trim()) '
vars.Unlock()

Dts.Connections("<oledb connection name>").Properties("ServerName").SetValue(oledbConnectionManager, oServerName)
Dts.Connections("<oledb connection name>").Properties("InitialCatalog").SetValue(oledbConnectionManager, oInitialCatalog)
Dts.Connections("<oledb connection name>").Properties("UserName").SetValue(oledbConnectionManager, oUserName)
Dts.Connections("<oledb connection name>").Properties("Password").SetValue(oledbConnectionManager, oPassword )

Dts.TaskResult = Dts.Results.Success

End Sub

Inside Entity Framework: Lazy Loading, Explicit Loading and Eager Loading

2012-01-18T02:15:00.001-08:00

When working with Entity Framework, it is important to understand how to hit the database and get the data especially to avoid the performance issues with the applications. That is exactly what I’m going to explain here that there are several ways to hit the database and load the related entities to retrieve the data. Also it is purely developer’s choice which one to use depending on the context to improve the performance.

Lazy Loading:

With lazy loading enabled, related objects are loaded when they are accessed through a navigation property. The default value of LazyLoadingEnabled is false. However, if we use the EF tools to create a new model and the corresponding generated classes, LazyLoadingEnabled is set to true in the object context's constructor by default. In this type of loading, each navigation property that we access causes a separate query to be executed against the data source.

Here is the simple example which is based on the assumption that there are three tables Organizations, Tenants and Facilities.
The relationship between these tables is :
Organization has multiple Tenants
Tenants have multiple Facilities

using (DatabaseEntities context = new DatabaseEntities())
{
context.ContextOptions.LazyLoadingEnabled = true;

var organizations = context.Organizations.Take(100);
var tenant = context.organizations.Where(org => org.TenantId == "T1").FirstOrDefault();

// If lazy loading was not enabled no Facilities would be loaded for the tenant.
foreach(Facilities facility in tenant.Facilities)
{
       Console.WriteLine("FacilityID: {0}", facility.facilityID);
}
}

Explicit Loading:

The following example in this topic show you how to explicitly load related objects by using the LoadProperty method on the ObjectContext. In this the Lazy Loading is set to false and we load the related entities explicitly each time. This example is based on the assumption that there are four tables: organizations, tenants, Facilities and ApplicationInstances. The relationship between these tables is an organization has multiple tenants, the tenants have multiple facilities and the facilities in turn have multiple ApplicationInstances.

using (DatabaseEntities context = new DatabaseEntities())
{
context.ContextOptions.LazyLoadingEnabled = false; // Disable Lazy Loading
context.MergeOption = MergeOption.AppendOnly;

var organization = context.Organizations.Where(org => org.OrganizationId == “org1”).FirstOrDefault();
context.LoadProperty(organization, org => org.Tenants);

var tenants = organization.Tenants.Where(tnt => tnt.TenantId == "T1").FirstOrDefault();
context.LoadProperty(tenants, tnt => tnt.Facilities);

var facility = tenants.Facilities.Where(fac => fac.FacilityId == "F1").FirstOrDefault();
context.LoadProperty(facility, fac => fac.ApplicationInstances);

var applicationInstances = facility.ApplicationInstances.Where(appIns => appIns.ApplicationInstanceId == "AI1");

foreach(var item in applicationInstances)
{
    Console.WriteLine("ApplicationInstanceID: {0}", item.applicationInstanceID);
}
}

Eager Loading:

There are circumstances that you may want only one query to hit the database and get the related entities rather than hitting every time. At times it may be a costlier operation to hit the database every time to load the related entities. In this scenario this Eager loading is very handy to do this operation. This example is based on the assumption that there are four tables: organizations, tenants, Facilities and ApplicationInstances. The relationship between these tables is an organization has multiple tenants, the tenants have multiple facilities and the facilities in turn have multiple ApplicationInstances.

DatabaseEntities context = new DatabaseEntities();
context.MergeOption = MergeOption.OverwriteChanges;

var organization = (from org in context.Organizations.Expand(tnt => tnt.Tenants.SubExpand(f => f.Facilities.
                 SubExpand(ai => ai.ApplicationInstances)))
         where org.OrganizationId == "T1"
         select org).First();

foreach (var tnt in organization.Tenants)
{
    foreach (var facility in tnt.Facilities)
    {
        foreach (var item in facility.ApplicationInstances)
        {
            //Do Something
        }
    }
}

Disposing WCF service after invoking in .NET

2012-01-18T02:14:00.000-08:00

There are so many ways available in .NET to invoke WCF services. In this article I will explain how to dispose after consuming or invoking WCF services.

There are three most commonly used ways to consume a WCF Service in a Service Oriented Application built on the WCF Infrastructure which are as follows:
a) Referencing WCF Service from VS.NET Studio 2010.
b) Executing ServiceModel Metadata Utility Tool (Svcutil.exe) and retrieve metadata from a WCF service and use it to create a WCF proxy that can access the service.
c) Using ChannelFactory<TContract> class used in advanced scenarios that can be used to create more than one channel(to create multiple endpoint listeners).

There are other approaches which are more advanced and less common to all. One such approach is generating proxy using the Mex service endpoints at runtime and another, worth mentioning is using the discovery API. No matter what approach is being used, the code block must always be executed the Dispose method so that it improves performance and releases memory right away (however, the GC still decides when to collect it).

Problem with invoking the Dispose method is due to the fact that there is no such design restriction in place which ensures the Dispose method always executes. Today, if you invoke Dispose method, you invoke it. If you don’t, you don’t. Well, you know your requirement and you got to execute it at any cost.

So, this ProxyInvoker class is designed to fill this gap using the power of lambda expression, Execute Around Method pattern and ChannelFactory<TContract> class. Well, there is another approach which is not so clean but it works is using .NET reflection. But this approach much either in a way that you need to specify the method name as string parameter and passing arguments as object[] value. On the other hand, this ProxyInvoker class is really a cool design which does exactly the same thing but works with type safety and performs better. It is a static class which provides two set of public methods that you can use to execute your WCF Service methods. It guarantees that the Dispose method is always executed and the Execute<> methods are all you have it.

First set of methods are defined to configure through configuration file from the serviceModel section:
object Execute<TContract> (string name, Func<TContract, object> invoker)
object Execute<TContract, THeader> (string name, THeader header, Func<TContract, object> invoker)

Second set of methods are defined to use explicitly the binding and address objects without a configuration file:
object Execute<TContract> (Binding binding, EndpointAddress address, Func<TContract, object> invoker)
object Execute<TContract, THeader> (Binding binding, EndpointAddress address, THeader header, Func<TContract, object> invoker)

Either case you need to write a code block that matches to Func delegate. And that’s where you are executing your type safe WCF methods.
The following code snippet shows the examples:
ProxyInvoker.Execute<IHelloService> (configName, (proxy) => { return proxy.Eecho(“Hello, World!”); }); ProxyInvoker.Execute<IHelloService>(binding, address, (proxy) => { return proxy.Eecho(“Hello, World!”); });

Finally, this is how the Execute<> method makes sure that dispose is invoked always:

try
{
if (header == null)
{
return invoker.Invoke((TContract)proxy);
}
using (OperationContextScope ocs = new OperationContextScope((proxy as IContextChannel)))
{
OperationContext.Current.OutgoingMessageHeaders

.Add( MessageHeader.CreateHeader(headerName, headerNamespace, header));

return invoker.Invoke((TContract)proxy);
}
}
finally
{
if (proxy != null) { proxy.Dispose(); }
}

Code Contracts - .NET Features

2012-01-18T02:11:00.000-08:00

How do you make sure your method guarantees to operate correctly under defined expected input states? Well Code Contracts may help you.

One of the fine features provided by .net 4.0 is Code Contracts. First it’s worth thinking a little about what contract means to you. They indicate the expected input states under which the method guarantees to operate correctly.

Contracts act as checked documentation of your external and internal APIs to be shipped. The code contracts are used to improve testing via runtime-checking, enable static contract verification. One of the interesting features of Code Contracts is that it includes a MSIL rewriter (ccrewrite.exe) that post-processes an assembly to change the intermediate language instructions emitted by the compiler. Another great feature of Code Contracts is that you can turn static analysis on and off on a per project basis. I believe this will be important to anyone practicing TDD and BDD.

A code contract follows design principle of Design By Contract (Dbc). This principle has 3 tenets which code contract also takes care of
a) Pre-condition:
Refer to the things it expect to do. These are expressed using Contract.Requires()

b) Post-condition:
Refer to the things it guarantees to do. These are expressed using Contract.Ensures()

c) Object Invariant:
Refer to things it maintains.

These are expressed using Contract.Invariant() Well, the tenets are fine for Dbc and .Net Code Contract follows each of these properly.
We will examine each of them in this article.

How?
The following example illustrates how the three main features of contracts are used.

a) Pre-condition
public Rational(int numerator, int denominator)
{
Contract.Requires(denominator!= 0);

this.numerator = numerator;

this.denominator = denominator;
}

The preconditions are generally used to specify valid parameter values. The example provided makes sure or checks that the denominator is not equal to zero. We can throw error if the condition is not satisfied using the overloaded method as below.
The example provided makes sure or checks that the denominator is not equal to zero. We can throw error if the condition is not satisfied using the overloaded method as below

b) Post-condition
Contract.Ensures(this.Result!= 0);

Basically the postconditions are checked /Executed before exiting the method call. The example provided checks/ Ensures that the result is not equal to zero. We can throw an exception if the condition is not satisfied using an overloaded method.

Contract.EnsuresOnThrow<ArgumentException> (this.Result!=0);

c) Object Invariant
public int EMIPercentage
{
get; private set;
}

[ContractInvariantMethod]
void ObjectInvariant()
{
Contract.Invariant(this. EMIPercentage >= 0);
}

The object invariants are conditions that should hold on each instance of your class whenever the object is visible. They express the condition under which the object is in a “good” state. The methods are identified with [ContractInvariantMethod] attribute. The invariants are checked at the end of each public method call. In the example above the denominator will checked at the end of each public method.

NoSQL - MongoDB

2012-01-18T00:44:00.000-08:00

1. Introduction / Overview

In the current software industry that work around design patterns and OOPs there is being a constant battle in converting the data from the database (RDBMs like MS Sql Server/Oracle…etc) into the objects in the object graph and vice versa. For simpler object models this is not a problem but when the model becomes complex it becomes too complicated.

2. Description

As more and more complication gets added into this conversion of data people started thinking why do I need to always keep my data in the database, why can’t I save it in a non-relational manner, is it necessary for me to go in the relational way. This then lead to a movement which started promoting loosely defined classes of non relational data stores. That movement then got the name NoSQL.

These NoSQL data stores usually avoid joins, may not require fixed table schemas and typically scale horizontally. As they don’t have joins or fixed table schemas they provide weak consistency guarantees and transactions are always restricted to single data items.

Note:- In case if we need ACID guarantees for our application using NoSQL then we can implement the necessary logics in the middle layer. But if it becomes too complex then we may need to stop with NoSQL and go with the RDBMs approach.

As this movement started gaining more support, a lot of NoSQL data stores came to the market. These data store are then categorized based on the way they are implemented. The following lists some of the categories and the NoSQL implementations

Document Store
• Lotus Notes
• CouchDb
• MongoDb

Graph• Neo4j
• AllegroGraph

Key/value store on disk• Tuple space
• Memcachedb
• Redis
• SimpleDb

Key/Value cache in RAM
• Memchaced
• Velocity
• Redis

Eventually consistent key value store
• Dynamo
• Cassandra
• Project Voldemort

Key-value stores implementing Paxos
• Keyspace

Object database
• Db4o
• InterSystems Caché
• Objectivity/DB
• ZODB

Note:- The above table is not the complete list and it keeps on growing. I have just highlighted some of the data stores.

From these implementations we will now take MongoDb and see how we can work it.

MongoDb

MongoDb is an open source document based data store and it combines the features of Key-Value data stores which are fast and highly scalable and RDBMSes which provides rich querying capabilities. It is fully written in C++ and is scalable.

The data in mongodb are stored as BSON documents which is nothing but binary en- coded serialization of JSON-like documents. BSON, like JSON, supports the embedding of objects and arrays within other objects and arrays. More details on the BSON specification can be obtained from www.bsonspec.org.

In MongoDB we can have one more database and every database will have one or more collections. Here collections are similar to tables in RDBMSes. Each collection will be a collection of documents.

Installation

MongoDb is available both in pre-built distribution as well as in source and if available for the following OS Linux, OS X and Windows. Installation of MongoDb using the built distribution is very simple and we will follow it.

The first step in the installation process is to download the distribution from http://www.mongodb.org/display/DOCS/Downloads. Once downloaded, we then need to unzip it in a folder in the harddisk. We then need to create a folder for MongoDb to store the data files. This folder should have read/write and directory creation permission for Mongodb. By default mongodb will store the data in [The drive when the distribution is extracted]\data\db. This directory has to be created manually and required permission should be given. We can also specify a different directory by using the --dbpath flag when starting mongodb server. Once these steps are completed the installation is complete. The following figure displays the installation structure
Figure 1

The following table describes the various applications that are available.

Application Description
--------------------------------------------------------------------------------
Mongo.exe The database shell
Mongod.exe The core database server
Mongos.exe The auto sharding process
Mongodump.exe The database dump utility
Mongorestore.exe The database restore utility
Mongoexport.exe The database export utility
Mongoimport.exe The database import utility

Starting and stopping MongoDB

Starting

MongoDB can run as a standard program from the command line. In its simplest form with all the default settings all we have to do is to just mongod from the command prompt and the server will be started.
Figure 2

Note:- by default mongodb server will be listening on port 27017 so make sure that the windows firewall is configured to allow that port.

If we want to make mongodb look for a different directory for e.g e:\mymongodb for storing the data store then we need to start mongodb using the –dbpath option as follows:

<your installation drive and folder>/bin/mongod –-dbpath e:\mymongodb

If we want to make mongodb listen on different port other than the default one then we can use the –port option:

<your installation drive and folder>/bin/mongod –port 1001

Again make sure that the firewall is configured to allow this port. We can also use –help option to get a list of all the allowed options The figure figure-4 lists the available list of options.

Once the server is started we can verify the server by connecting to it from the mongo console. In order to do that open another command window and go to the installation folder and type mongo as shown in figure 3
Figure-3

Figure 4

Stopping

Once the server is started we can stop by typing CTRL-C from the command prompt where the server is started or by calling the database method shutdownServer from the mongo console as shown in figure 5

Figure 5 Mongo console

Once the method is called the server will start to shutdown as shown in figure 6
Figure 6 mongod server console

Note: we can call shutdownServer only if we are within the admin database so go to the admin database (by calling use admin from within the mongo console) before calling shutdownServer.

Using mongo console
The mongo console is another utility that can be used to work the MongoDB database from the command prompt or also called shell. This utility can be used to do any operation on the MongoDB data store from the command prompt. We have already seen how we can use the mongo console to initiate the shutting down of the server.

If we have started mongo server with the default options then we can connect to the server by just typing mongo from the command prompt as follows
<your installation drive and folder>/bin/mongo
If we have started mongo server with a different port for e.g 1001 then we need to specify them using the –port option as follows
<your installation drive and folder>/bin/mongo –port 1001
By using the –help option we will a list of all the options available

Figure 7

We can get a list of the available database by using the command show dbs from within the mongo console as shown below

Figure 8

Once we know which database to work with we can use the ‘use’ command to select a database and start working with it

Figure 9

Note :- If MongoDb is started in secure mode by using –auth setting then we can work with the database only if we have access to it and only after we successfully logged into the database.

From with in the console we can type db.help() to see a list of all the options that are available to work with the database.

Figure 10

Note: All the method calls are case sensitive db.shutDownServer() and db.shutdownServer() are both different so ensure that you use proper case with calling the method.

Security

The current version of MongoDB only supports very basic security. One can authenticate a username and password only in the context of a particular database. Once authenticated, the user will have full read and write access to that database. If the user has only read only access then he will have only read access to that database. The admin database is a special one if you have access to the admin database then you can work with any database. So it is always advisable to restrict access to this database.

If we want to use this secure access then we need to start mongod with –auth option
<your installation drive and folder>/bin/mongod –auth

Once mongod is started with this option only after the user is authenticated he can work with any database from the console. If not he will get authentication exception as shown in figure below

Figure 11

We can login into a database by calling the db.auth method from the console and passing in the username and password. Before calling the auth method we need to make the database as the current database by calling use dbname from the mongo console. The following figure shows that in which we have made admin as the current database and logged into it.

Figure 12

A return value of 1 says that the login is successful.

We can add a user to a database by calling the method addUser by passing the required user name, password. The following example creates a user “user1” with password “password1” in the database BlogEngine
>use BlogEngine
>db.addUser (“user1”,” password1”)
In case if you want to give only read-only access then we can pass in the third parameter as true which will give only read only access to the database to the user.
>use BlogEngine
>db.addUser (“user1”,” password1”, true)
If we want to update the password then we can call addUser by passing the username to update and the updated password. The add user method when called will check for the user name if the user is not found then it will create a new user or else it will update the password of the user. So we need to be careful when calling addUser method
>use BlogEngine
>db.addUser (“user1”,” password123”)
The above command will update the password of the user “user1” to password123.

All the authentication information is stored in each database's system.users collection. So we can get a list of all the users within a collection by listing out all the data with this collection. The following figure lists the users within the admin database

Figure 13

We can remove a user by calling the remove method on the users collection and passing in the name of the user. The following command will remove the user “user1” from the BlogEngine database
>use BlogEngine
>db.system.users.remove ({user: “user1”})

The default option and recommended one for implementing security in MongoDB is to run the Mongo database in a trusted environment, with no security and authentication. And then ensure only trusted machines can access database TCP ports.