Understanding SOAP and REST

Which is better SOAP or REST? One of the most common discussions. Both REST and SOAP are different approaches in writing the service oriented applications. REST is an architectural style for building client-server applications. SOAP is a protocol for exchanging data between two endpoints.

It is more appropriate if you compare REST with RPC(remote procedure call). RPC is a style of building client-server applications. Compared to RPC there won’t be generated proxy for client which is less coupled to the service.

REST relies on HTTP, requests for data[Get requests] can be cached. RPC systems not having such infrastructure even when using SOAP over HTTP.

Both REST and SOAP can used to implement similar functionality but SOAP should be used when a particular feature of SOAP is needed.

Security

Is SOAP is more secured than REST? answer is no. It is easy to make REST based service secure as it is to make SOAP service.The security in REST  is in the form of HTTP-based authentication and Secure Sockets Layer(SSL).  Because of WS-* specifications SOAP supports the end-to-end message security.

Transactions

This is another feature that SOAP and WS-*  supports where REST has none.

WS-Atomic transactions supports distributed, two-phase commit transactional semantics over SOAP-based services. REST has no support for distributed transactions. To create something like transactions in REST you create a  resource called Transaction. When client wants to do some transaction and then he creates a resource that specifies all the correct resources.

Interoperability

SOAP services are less interoperable than REST Services. In terms of platforms, For REST all you need is HTTP stack. REST has widest interoperability like mobile devices,household devices, POS devices etc. The problem in SOAP and WS-* is the large number of standards to choose from.

Metadata

There is no direct way in REST to generating client from server-side-generated metadata. In SOAP with WSDL we can generate the client proxies. In REST we can achieve the same using WADL (Web Application Description Language). WSDL makes easier in generating the proxy than writing some code fro generating for REST service.

Protocol Support

Though REST is currently tied with HTTP but you still can implement the REST features on other protocols until vendors add support for this.

IS REST is for Internet-facing apps and SOAP for enterprise apps?

Answer is no. This question comes due to lack of distributed transaction support in REST vs explicit WS-atomic transactions in SOAP.

ASP.NET doesn’t have support for distributed transactions, but does that mean ASP.NET isn’t useful for enterprises?

Enterprise applications need scalability and speed. SOAP services are much harder to scale than RESTful services. Most of the scaling features can not be used with SOAP because SOAP uses POST only over HTTP.

Conclusion

“Which is better, REST or SOAP?” is “It depends”. Both REST and SOAP has advantages and disadvantages when it comes to building the services. When you need the features that are easy to implement using REST or SOAP choose it..

Difference Between Add Service Reference And Web Reference?

Service References or WCF comes from VS 2008 and above with an extension as .svc and Web References are their from the beginning as .asmx.

The main difference between WCF service and Webservice while consuming, we need to add them in solution as reference to access them.

Add Web Reference is a wrapper over wsdl.exe and can be used to create proxies for .NET 1.1 or 2.0 clients. This means we are pointing to a WCF service you have to be pointing to an endpoint that uses basicHttpBinding.

Add Service Reference is a wrapper over svcutil.exe and also creates clients proxies (and additionally web.config entries). These proxies, however, can only be consumed by .NET 3.0+ clients.

Below image will show you how to add web reference from Service Reference. Right click theService References from solution explorer, then select advance button on Add Services windowyou will get to the form as in below image and then will be able to add Web Reference via Addweb Reference window..

But there is some things which changed in VS2010 about adding web references to a class library. So in VS 2010 you cannot add Web Reference directly.  Here is how you need to do it.

From Project -> Add Service Reference ..., (From Solution Explorer, Right Click on Project, From the drop down Menu, Select Add Service Reference)

This window will appear, Click advanced,

On Add Service Settings window, Now click on Add Web Reference

This will open add Web reference window from where we can add web service. Hope this helps. Good luck.

How to add a ServiceThrottlingBehavior to a WCF Service?

When working with WCF especially when middle-tier client applications uses Windows Communication Foundation, you should always think about performance and take some major design decisions and tuning parameters.

By adding ServiceThrottlingbehavior in web.config we can achieve high performance using WCF. Below is the sample serivceThrottleconfiguration settings in web.config in .NET 4.0 Framework.

 <behaviors>
      <serviceBehaviors>
        <behavior name="CommonService">
          <serviceMetadata httpGetEnabled="true" />
          <serviceDebug includeExceptionDetailInFaults="false" />
          <dataContractSerializer maxItemsInObjectGraph="2147483647" />
          <serviceThrottling maxConcurrentCalls="16" 
                             maxConcurrentInstances="116"   
                             maxConcurrentSessions="100"   />
        </behavior>
      </serviceBehaviors>
    </behaviors>

The main purpose for the throttling settings can be classified into the following two aspects:

1. Controlled resource usage: With the throttling of concurrent execution, the usage of resources such as memory or threads can be limited to a reasonable level so that the system works well without hitting reliability issues.


2. Balanced performance load: Systems always work in a balanced way when the load is controlled. If there are too much concurrent execution happening, a lot of contention and bookkeeping would happen and thus it would hurt the performance of the system.

In WCF 4, the default values of these settings are revised so that people don’t have to change the defaults in most cases. Here are the main changes:

• MaxConcurrentSessions: default is 100 * ProcessorCount


• MaxConcurrentCalls: default is 16 * ProcessorCount


• MaxConcurrentInstances: default is the total of the above two, which follows the same pattern as before.

“ProcessorCount” is used as multiplier for the settings. So on a 4-proc server, you would get the default of MaxConcurrentCalls as 16 * 4 = 64. Thus the consideration is that, when you write a WCF service and you use the default settings, the service can be deployed to any system from low-end one-proc server to high-end such as 24-way server without having to change the settings. So CPU uses count as the multiplier.

Please note, these changes are for the default settings only. If you explicitly set these settings in either configuration or in code, the system would use the settings that you provided. No “ProcessCount” multiplier would be applied.

WCF OperationContractAttribute with example

The OperationContractAttribute, also defined in the System.ServiceModel namespace, can be applied only to methods. It should declare to the method which belongs to a Service contract. Operation contract can be declared with below named parameters that provide control over the service description and message formats.

Name Specifies a different name for the operation instead of using the default, which is the method name.Action Controls the action header for messages to this operation.

ReplyAction Controls the action header for response messages from this operation.

IsOneWay Indicates whether the operation is one-way and has no reply. When operations are one-way, ReplyAction is not supported.

ProtectionLevel Enables the Service contract to specify constraints on how messages to
all operations in the contract are protected on the wire, that is, whether they are signed and encrypted.

IsInitiating Indicates whether invoking the operation initiates a new session between the caller and the service.

IsTerminating Indicates whether invoking the operation terminates an existing session between the caller and the service

Here is Sample WCF Class for reference.

// C#
[ServiceContract(Namespace = "")]
public class CrudContract
{
    [OperationContract(IsOneWay = true, Action = "urn:crud:insert")]
    void ProcessInsertMessage(Message message);
    [OperationContract(IsOneWay = true, Action = "urn:crud:update")]
    void ProcessUpdateMessage(Message message);
    [OperationContract(IsOneWay = true, Action = "urn:crud:delete")]
    void ProcessDeleteMessage(Message message);
    // The catch-all operation:
    [OperationContract(IsOneWay = true, Action = "*")]
    void ProcessUnrecognizedMessage(Message message);
}

Hope this is useful

Iterating through Generic List in C#

Recently I need to loop through a Generic list and bind the result to a Combobox. Here is how you can do this in C#

List<CCDSDateResult> list = new List<CCDSDateResult>();
for (int i = 0; i < e.Result.Count; i++)
{
    if (e.Result.ToList()[i].ccds_date.ToString().Length > 0)
    {
        // Write your logic..to add item in the list
        list.Add(new CCDSDateResult(DateTime.Parse(e.Result.ToList()[i].ccds_date.ToString())));
    }
}
// adding a empty record to the list
list.Insert(0, new CCDSDateResult());
this.OrderComboBox.ItemsSource = list.ToList();

Hope this is useful.

How to: Deploying Sliverlight applications in different machines

I am working on my silverlight application and i need to deploy the same on multiple machines as i need to test its performance on different servers.

Here is a small work around to do this.

• Unzip the .XAP file in the clientBin folder of the website with WinRar or other archivator or Rename your XAP file to zip
• Extract the zip file to a folder
• Edit ServiceReference.ClientConfig in notepad
• Here is the snippet of ServiceReference.ClientConfig.

<configuration>
    <system.serviceModel>
        <bindings>
            <customBinding>
                <binding name="CustomBinding_DPService" closeTimeout="00:10:00" openTimeout="00:10:00" sendTimeout="00:10:00"  receiveTimeout="00:10:00">
                    <binaryMessageEncoding />
                    <httpTransport maxReceivedMessageSize="2147483647" maxBufferSize="2147483647">
                        <extendedProtectionPolicy policyEnforcement="Never" />
                    </httpTransport>
                </binding>
            </customBinding>
        </bindings>
        <client>
            <endpoint address="/SLSampleWebsite/DPService.svc" 
                binding="customBinding" bindingConfiguration="CustomBinding_DPService"
                contract="ServiceReference1.DPService" name="CustomBinding_DPService" />
        </client>
    </system.serviceModel>
</configuration>

• Update the endpoint address in the XML with relevant address if its hosted in different machine or in the same machine.



• Add the folder contents to ZIP file

            <endpoint address="http://Server1/SLSampleWebsite/DPService.svc" 

• After updating the ServiceReference.ClientConfig, Compress all files again to create new .ZIP file.



• Delete the old .XAP file and remame the .ZIP to XAP file

It works great!

Handling large sets of data from WCF service in Silverlight application

I had the problem of handling data which is coming from my WCF web service to Silverlight application. When data is huge i got communication exception. I have googled on this and found a great article to handle huge amount of data.

Here is a great article by Syed Mehroz Alam. I found it very helpful.

What is WCF?

 

A WCF Service is a program that exposes a collection of Endpoints. Each Endpoint is a portal for communicating with the world.

A Client is a program that exchanges messages with one or more Endpoints. A Client may also expose an Endpoint to receive Messages from a Service in a duplex message exchange pattern.

Service Endpoint:

A Service Endpoint has an Address, a Binding, and a Contract.

The Endpoint's Address is a network address where the Endpoint resides. The EndpointAddress class represents a WCF Endpoint Address.

The Endpoint's Binding specifies how the Endpoint communicates with the world including things like transport protocol (e.g., TCP, HTTP), encoding (e.g., text, binary), and security requirements (e.g., SSL, SOAP message security). The Binding class represents a WCF Binding.

The Endpoint's Contract specifies what the Endpoint communicates and is essentially a collection of messages organized in operations that have basic Message Exchange Patterns (MEPs) such as one-way, duplex, and request/reply. The ContractDescription class represents a WCF Contract.

The ServiceEndpoint class represents an Endpoint and has an EndpointAddress, a Binding, and a ContractDescription corresponding to the Endpoint's Address, Binding, and Contract, respectively

An EndpointAddress is basically a URI, an Identity, and a collection of optional headers.

An Endpoint's security identity is normally its URI; however, in advanced scenarios the identity can be explicitly set independent of the URI using the Identity address property.

The optional headers are used to provide additional addressing information beyond the Endpoint's URI. For example, address headers are useful for differentiating between multiple Endpoints that share the same address URI.

A Binding has a name, a namespace, and a collection of composable binding elements.
The presence of each binding element describes part of the how of communicating with the Endpoint. The TcpTransportBindingElement indicates that the Endpoint will communicate with the world using TCP as the transport protocol. ReliableSessionBindingElement indicates that the Endpoint uses reliable messaging to provide message delivery assurances. SecurityBindingElement indicates that the Endpoint uses SOAP message security.

For example, the ReliableSessionBindingElement has an Assurances property that specifies the required message delivery assurances, such as none, at least once, at most once, or exactly once.

A WCF Contract is a collection of Operations that specifies what the Endpoint communicates to the outside world. Each operation is a simple message exchange, for example one-way or request/reply message exchange.

The ContractDescription class is used to describe WCF Contracts and their operations. Within a ContractDescription, each Contract operation has a corresponding OperationDescription that describes aspects of the operation such as whether the operation is one-way or request/reply. Each OperationDescription also describes the messages that make up the operation using a collection of MessageDescriptions.

A ContractDescription is usually created from an interface or class that defines the Contract using the WCF programming model. This type is annotated with ServiceContractAttribute and its methods that correspond to Endpoint Operations are annotated with OperationContractAttribute. You can also build a ContractDescription by hand without starting with a CLR type annotated with attributes.

A duplex Contract defines two logical sets of operations: A set that the Service exposes for the Client to call and a set that the Client exposes for the Service to call. The programming model for defining a duplex Contract is to split each set in a separate type (each type must be a class or an interface) and annotate the contract that represents the service's operations with ServiceContractAttribute, referencing the contract that defines the client (or callback) operations. In addition, ContractDescription contains a reference to each of the types thereby grouping them into one duplex Contract.

Similar to Bindings, each Contract has a Name and Namespace that uniquely identify it in the Service's metadata.

Each Contract also has a collection of ContractBehaviors that are modules that modify or extend the contract's behavior. The next section covers behaviors in more detail.

For more details, visit this link at MSDN.

Deploying WCF Service in IIS : no svc MIME Type

I have started My First SilverLight application with WCF Service. When i want to deploy on IIS, i got this error saying no MIME type for this extension SVC not found. It is happening because this MIME type is not registered IIS.

Exception Details:

Server Error in Application “Default Web Site/MyFirstSLApp”
HTTP Error 404.3 – Not Found
Description: The page you are requesting cannot be served because of the Multipurpose Internet Mail Extensions (MIME) map policy that is configured on the Web server. The page you requested has a file name extension that is not recognized, and is not allowed.
Error Code: 0×80070032

I tried IIS MIME Types and I couldn’t found an application mapping for SVC file. After doing some goggling I found the fix.  You can resolve this using WCF Installation utility which comes with .Net Framework 3.0. Run the command prompt as Administrator, go to the Windows Communication Foundation folder in c:\Windows\Microsoft.NET\Framework\v3.0\ folder. Execute the servicemodelreg.exe with -i or /i switch.

 

After the installation this try reloading the Page. It will fix this issue.

Microsoft .NET Framework 3.0 (Brief Overview)

 

What is the Microsoft .NET Framework 3.0?
The Microsoft .NET Framework 3.0 (formerly WinFX), is the new managed code programming model for Windows.

It combines the power of the .NET Framework 2.0 with four new technologies:
Windows Presentation Foundation (WPF),
Windows Communication Foundation (WCF),
Windows Workflow Foundation (WF), and
Windows CardSpace (WCS, formerly “InfoCard”).

Use the .NET Framework 3.0 today to build applications that have visually compelling user experiences, seamless communication across technology boundaries, the ability to support a wide range of business processes, and an easier way to manage your personal information online. This is the same great WinFX technology you know and love, now with a new name that identifies it for exactly what it is – the next version of Microsoft’s development framework.

What is Windows Communication Foundation ?
The Windows Communication Foundation (previously codenamed "Indigo") is Microsoft's unified framework for building
secure, reliable, transacted, and interoperable distributed applications.

What is Windows Presentation Foundation ?

Windows Presentation Foundation (WPF) is the next-generation presentation sub-system for Windows.

It provides developers and designers with a unified programming model for building rich Windows smart client user experiences that incorporate UI, media, and documents.

What is Windows Workflow Foundation?

Windows Workflow Foundation (WF) is the programming model, engine and tools for quickly building workflow enabled applications.

WF radically enhances a developer’s ability to model and support business processes.

Windows Workflow Foundation is a part of the .NET Framework 3.0 that enables developers to create workflow enabled applications. It consists of the following parts:

Activity Model:
Activities are the building blocks of workflow, think of them as a unit of work that needs to be executed.

Activities are easy to create, either from writing code or by composing them from other activities. Out of the box, there are a set of activities provided that mainly provide structure, such as parallel execution, if/else, call web service.

Workflow Designer:
This is the design surface that you see within Visual Studio, and it allows for the graphical composition of workflows, by placing activities within the workflow model.
One interesting feature of the designer is that it can be re-hosted within any Windows Forms application.

Workflow Runtime:
Our runtime is a light-weight and extensible engine that executes the activities which make up a workflow.

The runtime is hosted within any .NET process, enabling developers to bring workflow to anything from a Windows Forms application to an ASP.NET web site or a Windows Service.

Rules Engine:
Windows Workflow Foundation has a rules engine which enables declarative, rule-based development for workflows and any .NET application to use.

Windows Workflow Foundation will be released as part of the .NET Framework 3.0 which is part of the Windows Vista release. The .NET Framework 3.0 will be available for Windows XP as well as Windows Server 2003

What is Windows Card Space ?
Windows CardSpace enables users to provide their digital identities in a familiar, secure and easy way.

In the physical world we use business cards, credit cards and membership cards.

Online with CardSpace we use a variety of virtual cards to identify ourselves, each retrieving data from an identity provider. Don't struggle with usernames and passwords, just choose an information card!