In this article I am going to demonstrate the following
- Creation of a WCF service in Worker Role
- Deployment to the cloud
- Testing with a client
The attributes of a WCF service on a Worker role
are:
- Self Hosted
- More Flexibility Attained
- More Configuration Needed
The following are the steps involved.
Step 1: Create the WCF Service
Create a new Windows Azure project in Visual Studio 2010 and name it WCFInWorkerRole as shown below
In the appearing dialog add one Worker Role project as shown below.
Add a reference to the System.ServiceModel assembly.
Add the following 2 files
- Interface named IMessengerService
- Class named MessengerService
Replace the contents of the above files with the
following:
// IMessengerContract.cs
using
System;
using
System.Collections.Generic;
using
System.Linq;
using
System.Runtime.Serialization;
using
System.ServiceModel;
using
System.Text;
namespace
WorkerRole1
{
[ServiceContract]
public
interface
IMessengerService
{
[OperationContract]
string
SendMessage(string
name);
}
}
// MessengerService.cs
using
System;
using
System.Collections.Generic;
using
System.Linq;
using
System.Runtime.Serialization;
using
System.ServiceModel;
using
System.Text;
namespace
WorkerRole1
{
public
class
MessengerService
:
IMessengerService
{
public
string
SendMessage(string
name)
{
return
"Hello "
+ name +
". How do you do?";
}
}
}
Remove the app.config from the worker role project as we are going to do manual
configuration of the WCF service. Now the solution explorer looks like below:
In the case of a web role, the context and port was automatically identified. But
in the worker role, we need to update the properties manually. The host name
will be different in the development and deployment servers.
Modify the ServiceDefinition.csdef file as below.
<?xml
version="1.0"
encoding="utf-8"?>
<ServiceDefinition
name="WCFInWorkerRole"
xmlns="http://schemas.microsoft.com/ServiceHosting/2008/10/ServiceDefinition">
<WorkerRole
name="WorkerRole1"
vmsize="Small">
<Imports>
<Import
moduleName="Diagnostics"
/>
</Imports>
<Endpoints>
<InputEndpoint
name="port"
protocol="tcp"
port="9001"
/>
<InputEndpoint
name="mexport"
protocol="tcp"
port="8001"
/>
</Endpoints>
</WorkerRole>
</ServiceDefinition>
The content defines the port and metadata port for our WCF service. Now we can
modify the OnStart() method of the Worker role class as given below.
public
override
bool
OnStart()
{
// Set the maximum number of concurrent connections
ServicePointManager.DefaultConnectionLimit
= 12;
//
Create the host
ServiceHost
host =
new
ServiceHost(typeof(MessengerService));
//
Read config parameters
string
hostName =
RoleEnvironment.CurrentRoleInstance.InstanceEndpoints["port"].IPEndpoint.Address.ToString();
int
port =
RoleEnvironment.CurrentRoleInstance.InstanceEndpoints["port"].IPEndpoint.Port;
int
mexport =
RoleEnvironment.CurrentRoleInstance.InstanceEndpoints["mexport"].IPEndpoint.Port;
//
Create Metadata
ServiceMetadataBehavior
metadatabehavior =
new
ServiceMetadataBehavior();
host.Description.Behaviors.Add(metadatabehavior);
Binding
mexBinding =
MetadataExchangeBindings.CreateMexTcpBinding();
string
mexendpointurl =
string.Format("net.tcp://{0}:{1}/MessengerServiceMetadata",
hostName, 8001);
host.AddServiceEndpoint(typeof(IMetadataExchange),
mexBinding, mexendpointurl,
new
Uri(mexendpointurl));
//
Create end point
string
endpointurl =
string.Format("net.tcp://{0}:{1}/MessengerService",
hostName, 9001);
host.AddServiceEndpoint(typeof(IMessengerService),
new
NetTcpBinding(SecurityMode.None),
endpointurl,
new
Uri(endpointurl));
//
Open the host
host.Open();
//
Trace output
Trace.WriteLine("WCF
Listening At: "
+ endpointurl);
Trace.WriteLine("WCF
MetaData Listening At: "
+ mexendpointurl);
return
base.OnStart();
}
The code performs the following:
Note: The attached source code contains the working application.
Step 2: Test the application
Now we can test the application by executing it. If successfully executed we can
see the trace from the Output window.
You can see two addresses from the above screen:
We can also see the trace from the load development machine. The Windows Azure
Compute Emulator can be used for this purpose.
On invoking the Show Computer Emulator UI we can see the following window.
The above window contains the same trace output with the end point urls. You may
try adding reference to the metadata end point using the metadata url. We are
going to deploy the service to cloud and test it.
Step 3: Deploy to the cloud
Now our application is working fine and we can deploy it to the online cloud.
For this right click on the project and click the Package menu item.
In the appearing dialog box, choose the default options and click the Package
button.
Now sign in to the Windows Azure portal and click on the New Hosted Service
button from the top ribbon.
In the appearing dialog box enter the details as shown below.
Choose the option "Deploy to production environment"
Locate the package and configuration files from your application bin folder.
(Eg: ..\WCFInWorkerRole\bin\Debug\app.publish)
Please note that the URL prefix should be a unique name. If the URL prefix
entered is already in use you need to change it.
After that click the Ok button of the dialog box. (You have to scroll down to
see the button)
If any warning box appears, click Yes button to continue. Wait for a few minutes
and your deployment will be ready in a few minutes as shown below.
Select the Deployment 2 row and from the properties window you can get the url
of the worker role. Now we just need the host name. In this case
wcfinworkerrole.cloudap.net
Step 4: Create the Client
Now we are ready to create the client application and test the deployed online
cloud WCF service.
Create a new console application into the existing Azure project and name it as
TestClient.
Use the add service reference option of the console application and in the
appearing dialog enter the constructed service url as shown below.
Constructed Url: net.tcp://wcfinworkerrole.cloudapp.net:8001/MessengerServiceMetadata
Please note that we added the following:
Click the Go button and after seeing the MessengerService item populated, Click
the Ok button to continue.
Modify the main method in the Program.cs as following:
static
void
Main(string[]
args)
{
ServiceReference1.MessengerServiceClient
client =
new
ServiceReference1.MessengerServiceClient();
string
result = client.SendMessage("Kent");
Console.WriteLine(string.Format("Invoking
WCF Service Result: {0}",
result));
Console.ReadKey(false);
}
Modify the configuration file with the url of the Messenger Service. Please note
that the messenger service url is having different port number and context.
<client>
<endpoint
address="net.tcp://wcfinworkerrole.cloudapp.net:9001/MessengerService"
binding="netTcpBinding"
bindingConfiguration="NetTcpBinding_IMessengerService"
contract="ServiceReference1.IMessengerService"
name="NetTcpBinding_IMessengerService"
/>
</client>
Now set the console application as the start project and execute the
application.
You can see the following results.
You can see the result Hello Kent. How do you do? from the WCF service.
This concludes our article on WCF service deployment as worker role and the
testing.
Multiple End Point
I would like to add a note on the 2 end points we created for the WCF service.
net.tcp://wcfinworkerrole.cloudapp.net:8001/MessengerServiceMetaData \
net.tcp://wcfinworkerrole.cloudapp.net:9001/MessengerService
You can see that there are 2 differences in the above urls:
Note: WCF with HTTP Port 80 endpoint configuration done as explained
here.
Summary
In this article, we have seen how to host a WCF service using the Worker Role
and deploy it to the cloud. This service is self hosted and experiments the
service creation, hosting, metadata end point adding, deploying and testing with
the client. The source code is attached and the application name in the url has
to be changed according to your application name.