1. Windows Communication Foundation and Web Services

2. Some OOP Prerequisites
Understand the purpose of interfaces
Understand the purpose of .net attributes
Introduce WCF

3. A Word About Attributes
The statements inside the brackets are called attributes
And they are used everywhere (Xamarin, etc)
Attributes are declarative information about
C# code
Assemblies
And much more
Don’t confuse the term attribute here with an HTML attribute

4. Attributes (Example) Some attributes belong to an assembly
Set using positional parameters or key=value pairs
[assembly: AssemblyVersion(" ")]

5. A Word About Interfaces
An interface contains the signatures of methods, properties, events or indexers
A class that implements the interface must implement the members of the interface that are specified in the interface definition
It’s how we build structured contracts
The interface name typically start with the letter I (capitalized)

6. A Word About Interfaces
The interface ISampleInterface has one method named SampleMethod
The class named ImplementationClass implements ISampleInterface
It implements SampleMethod

8. WCF (Introduction)
It’s Microsoft’s current inter-machine communication foundation used to integrate
HTTP requests and responses
Web Services
WSDL, SOAP and more
Messaging
Lower-level TCP/IP
Ajax / REST services
And everything else

9. And I’ll start out by saying it’s complicated
WCF (Introduction)
And I’ll start out by saying it’s complicated

10. WCF Fundamentals
Simply put, WCF is a set of APIs used to send messages between services and clients
Messages are sent between endpoints using a transport protocol
such as HTTP, TCP, and others

11. WCF Model (1)

12. WCF Model (2)

13. WCF Model (Contracts)
Service contracts describe the precise format of messages
This is done using HTTP or another protocol
The service contract defines the interface to the outside world
Operation contracts belong to a service contract
These are really the methods of the contract

14. WCF Model (Contracts) We are talking about the format of
Function calls
Parameters
Return types
These are message signatures
The programming model defines how we write the code to do all of this

15. WCF Model (Contracts)

17. WCF Model (Contract) Request-Reply
Request-Reply services
This is the default type of service
Clients make a request for service (synchronously or asynchronously)
Clients receive a response
Duplex services involve 2-day communication between hosts

18. WCF Model (Contract) One Way
In a One-Way service, the client sends a request but does not expect a response
To detect errors, create two One-Way service contracts

19. WCF Model (Contract) Duplex
Both endpoints can send messages independently
These are implemented using the idea of a callback
To implement, create two interfaces
The first is the one-way client interface
The second is the callback contract
Refer to

20. WCF Model (Service Runtime)
This layer defines the behavior of the runtime service (server configuration)
We configure the service runtime using behaviors
There is much more detail here beyond the scope of this course

21. WCF Model (Service Runtime)
How many messages are processed at a time
InstanceContextMode / ConcurrencyMode
How many instances of a server can run (singleton)
InstanceContextMode
Threading and reentrancy
ConcurrencyMode

22. WCF Model (Messaging) Transport channels are of two types
Transport channels send and receive messages
TCP, HTTP, MSMQ
Protocol channels implement the messaging protocols
HTTP

23. WCF Model (Hosting)
Simply put, it’s where the application runs (is hosted)
Might be IIS or WAS

24. WCF Model (Hosting)

25. WCF Model (Hosting)

26. WCF Model (Hosting - IIS)
This is the easiest way to host your service
IIS treats the service as an ASP.NET Web Site
If you are using IIS6, then only HTTP and HTTPS are supported
You can create a self-hosted console (or forms) application that listens for requests at a particular port
We can also host through Azure Services

27. WCF and Web Services WCF has changed the .net picture of Web Services
They used to be a standalone product type etc…
They are now just another service within the context of WCF

28. The Goal of Web Services
Supply a standard means for e-commerce applications to communicate using different hardware and software platforms
Supply a way for legacy applications to communicate
Provide a universal way to discover the available services and the methods supplied by a particular service so that any consumer can call those methods

29. Logical Web Service Model

30. Web Service Vendors IBM – WebSphere Studio Application Developer
SAP – SAP Web Application Server
SUN – Sun ONE Web Services Platform Developer Edition
And of course Microsoft and Visual Studio .NET
Others are likely to follow
No matter the vendor, Web services will always work the same way
Any consumer should work with any provider

31. Web Service Protocols
Web services provide a hardware and software agnostic way to call remote functions and return data from those remote functions
Protocols
HTTP is the message transfer agent
Simple Object Access Protocol (SOAP)
Web Service Description Language (WSDL)

32. Creating A Web Service
Create a new Web side using the WCF Service project type

33. Web Service (Steps to Create)
Design the service contract
Implement the service contract
This is done via attributes
Configure the service endpoints
Host the service
Build client applications

34. Web Service Implementation (Steps)
Declare the members of the interface that will be implemented in the .svc file
Implement those members in the corresponding class

35. The Role of App.Config App.Config operates similarly to Web.Config
Here, it’s used to configure a Web Service
All of this appears inside of <system.serviceModel>
We could also hardcode this

36. App.config (Bindings)
Bindings define the transport protocol details needed for a client to communicate with a service
Predefined (provided) bindings
<BasicHttpBinding>
<NetTcpBinding>
Custom bindings

37. App.config (Bindings)
Here we bind to three different services

38. App.config (Endpoints)
Endpoints allow clients to access a Web service
Consists of
An address (URL that points to the service)
Name of a binding (how to communicate with the endpoint)
The contract defining the methods available

39. App.config (Endpoints)
We communicate with three services

40. Service Contract
A service contract exposes one or more service operations
A ServiceContract defines the types of messages used in a conversation
A ServiceOperation defines the messages themselves

41. Service Contract (Example 1)

42. Service Contract (Example 2)
Use a class instead of creating an interface and implementing that interface

43. Data Contract
Simply put, simple types do not require a data contract. Complex types do
Serializable parameters do not require a data contract
A DataContract describes a type that will be serialized by the service
A DataMember describe the members of the DataContract type

44. Data Contract (Example 1)

45. Configure Service Endpoints (1)
Communication occurs through service endpoints and four properties
Address of the endpoint
A binding that specifies how a client can communicate with the endpoint
A contract the defines the allowable operations
Local implementation details

46. Configure Service Endpoints (2)
We can configure endpoints via
Code
In the config (web.config) file

47. Configure Service Binding (1)
Most bindings are provided with WCF
Use BasicHttpBinding for most Web services

48. Host the Service
IIS must be installed on the server

49. Compiling the Service
The service is compiled the same way as any other .NET app.
If you run it, you see a “special” test client window
The code is generated by .NET itself

50. Test Service (Illustration 1)

51. Test Service (Illustration 2)

52. Creating the Test Client
Create a WPF or Windows forms application
Insert the template code created by Svcutil.exe into this project
While the service is running locally, add a service reference
In a production app, you will have this URL
Change the name of the endpoint in app.config

53. Adding the Service Reference (Example)