Mahesh Krishnan Senior Consultant Readify PRACTICAL WCF PART

Mahesh Krishnan, Senior Consultant, Readify PRACTICAL WCF PART 1 Slide 1

Agenda � Introduction to WCF �What is it? Why use it? �Fundamentals and the ABCs of WCF �Hosting Tooling Support � Passing data around in WCF � Handling faults �

Introduction to WCF Slide 3

What is WCF? �Stands for Windows Communication Foundation �One of the 4 pillars of. NET 3. 0 �Microsoft’s unified programming model (the service model) for building Service-Oriented Applications

Windows Communication Foundation � WCF provides: �an SDK for creating SOA �a runtime for running Services on Windows � Services send and receive messages � All messages are SOAP messages � WCF takes care of all the plumbing Slide 5

Why use WCF? � Interoperable and Standards based �Supports WS-* protocols � Unified Programming Model �Unifies previous models like. NET Remoting, ASMX web services, COM+ etc � Productive Programming Model �Declarative �Imperative �Configuration based Slide 6

WCF: How does it work? Client SOAP Message Service

WCF End points AA= Address (Where) BB= Binding (How) CC= Contract (What) Client Service Message C B A A B C

WCF Endpoints Every service has � Address �Where the service is � Binding �How to talk to the service � Contract �What the service can do Slide 9

The End. Point Anology Get. Balance() Transfer. Money() Address Slide 10 Binding Contract

Address � Combination of transport, server name, port & path http: //server: 345/Service � Transport is determined by the binding � Examples http: //localhost: 8001 net. tcp: //localhost: 8002/My. Service net. pipe: //localhost/My. Pipe net. msmq: //localhost/private/My. Service net. msmq: //localhost/My. Service Slide 11

Bindings � Transport � HTTP � TCP � MSMQ � Message formats and encoding � Plain text � Binary � Message Transmission Optimization Mechanism (MTOM) � Communication security � No security � Transport security � Message security � Authenticating and authorizing callers Slide 12

Out of the box Bindings � � � Slide 13 Basic. Http. Binding WS 2007 Http. Binding WSDual. Http. Binding WSFederation. Http Binding WS 2007 Federation. Http Binding � � � Net. Tcp. Binding Net. Named. Pipe. Binding Net. Msmq. Binding Net. Peer. Tcp. Binding Web. Http. Binding Msmq. Integration. Binding

Contracts � Service contracts �Defines operations, communications and behaviours. � Data contracts �Defines data entities and parameter types. � Fault contracts �Defines error types � Message contracts �Defines message formats Slide 14

Service Contracts � � [Service. Contract] – Defines a ‘set’ of operations [Operation. Contract] – Defines a single method [Service. Contract] public interface IService { [Operation. Contract] string Get. Data(int value); } public class Concrete. Service : IService { public string Get. Data(int value) {. . . } public string Other. Method() {. . . } } Slide 15

Data Contracts [Data. Contract] – Specifies type as a data contract � [Data. Member] – Members that are part of contract � [Data. Contract] public class Custom. Type { [Data. Member] public bool My. Flag { get; set; } [Data. Member] public string My. String { get; set; } } Slide 16

Metadata Exchange � Service can also expose endpoint for Metadata Exchange (MEX) � It provides a mechanism for clients to find out about: �Address of other end points �Bindings that are used �Contracts used – Service, Operation, Data, etc Slide 17

Hosting � IIS �HTTP only � WAS (Windows Activation Service) �Can use any transport �Vista and Windows Server 2008 only � Self hosting �Can use any transport �Can be hosted within Console, Win. Forms, etc Applications Slide 18

Tooling Support Slide 19

Tooling Support � Visual Studio �Separate projects for WCF �“Add Service reference” menu �WCF Configuration Editor �WCF Service Host �WCF Test Tool � Svc. Util – To generate proxies � Svc. Trace. Viewer – To view logs Slide 20

Demonstration WCF in Action Slide 21

Passing data around in WCF Slide 22

Passing data around � To pass data across boundaries, they need to be serialized �. NET Framework already contains an attribute for serialization [Serializable] public class Person { public string Last. Name; public string First. Name; } Slide 23

Passing data around � Serializable Attribute has some limitations – �Includes some type information in serialized data – not suited for true SOA �Does not support aliases �Does not support versioning �Does not support ordering �Explicit opt-out is needed to leave out some properties that shouldn’t be serialized Slide 24

Alternative – Data. Contract � Data. Contract: created specifically for WCF to serialize types �Attribute contains Name and Namespace properties � Data. Member is needed to specify which properties/fields will form part of the contract �Contains Emit. Default. Value, Is. Required, Name, Order properties Slide 25

Data. Contract [Data. Contract(Name="Contact")] public class Person { [Data. Member(Is. Required=true, Name="Sur. Name")] public string Last. Name; public string First. Name; //Not included in contract } Slide 26

Versioning of data contracts � Three different scenarios: �New fields have been added �Existing fields have been deleted �Fields have been renamed Slide 27

Alternate way of looking at it: � Older version data [v 1] passed to Service accepting newer version of data [v 2] � Newer version data [v 2] passed to Service accepting older version of data [v 1] � New [v 2]-> Old [v 1]-> New [v 2] Slide 28

New -> Old -> New Slide 29

Proxy code to hold [Data. Contract] public class My. Data. Contract : IExtensible. Data. Object { public Extension. Data. Object Extension. Data { get; set; } } Slide 30

Inheritance with Data Contracts [Data. Contract] public class Employee {. . . } [Data. Contract] public class Manager : Employee {. . . } [Service. Contract] public interface IEmployee. Service { [Operation. Contract] public void Add. Employee(Employee e); } Slide 31

Inheritance with Data Contracts [Data. Contract] [Known. Type(typeof(Manager))] public class Employee {. . . } [Data. Contract] public class Manager : Employee {. . . } [Service. Contract] public interface IEmployee. Service { [Operation. Contract] public void Add. Employee(Employee e); } Slide 32

Handling Faults Slide 33

SOAP Faults � Three main kinds of Exceptions can occur: �Communication errors �Unexpected error on the service �Errors thrown by the service on purpose �. NET Exceptions are technology specific � All Exceptions come across the wire as SOAP Faults Slide 34

Faults � In WCF, SOAP faults are passed in as Fault. Exception objects � Rather than throwing Exceptions, services should throw Fault. Exceptions � Or better still Fault. Exception<T> � Throwing Fault. Exceptions will not fault the proxy and the channel Slide 35

Fault. Contracts � Specifies what kind of Exceptions, an operation can throw [Service. Contract] public interface IEmployee. Service { [Operation. Contract] [Fault. Contract(typeof(Validation. Exception))] public void Add. Employee(Employee e); } Slide 36

Server side code � Always throw Exceptions as Fault Exceptions public class Employee. Service { public void Add. Employee(Employee e) {. . . throw new Fault. Exception<Validation. Exception> (new Validation. Exception(error. Msg)); } } Slide 37

Client side code Employee. Service. Proxy proxy = new Employee. Service. Proxy(); try {. . . proxy. Add. Employee(emp); } catch(Fault. Exception<Validation. Exception> e) { //Do stuff with exception here } catch(Fault. Exception e) { //Will catch all other types of Fault exceptions. . . } Slide 38

Exceptions while developing <system. service. Model> <services> <service name = "Employee. Service" behavior. Configuration = "Debugging">. . . </service> </services> <behaviors> <service. Behaviors> <behavior name = "Debugging"> <service. Debug include. Exception. Detail. In. Faults = "true"/> </behavior> </service. Behaviors> </behaviors> </system. service. Model> Slide 39

Summary WCF provides a runtime for creating Service Oriented Apps � Provides a productive programming model. Takes care of: � � Messaging and Exchange formats � All Plumbing: Transaction, Reliability, Security, etc Supports Declarative (via attributes), Imperative (via code) and Configuration based (via config files) programming model � ABCs of Endpoints � � Address: Where to go? � Binding: How to get there? � Contract: What to do? � Hosting � IIS, WAS, Self-hosting

Summary (contd) Service. Contract and Operation. Contract specify Service and operation information � Data. Contracts and Data. Members are used for specifying the data that is passed across the wire � Use Known. Type attribute for specifying class hierarchy information in Data contracts � Fault. Contracts specify what Exceptions may be thrown by the operations �

Questions? Slide 42