Presentation 23: .NET Remoting Introduced

1. Presentation 23:.NET Remoting Introduced Objektorienteret Middleware

2. Outline • .NET Framework introduced • .NET Remoting • Strategies • Architecture • Remoting object types • Activation • Lifetime • Deployment • Example application • Windows Communication Foundation short intro

3. Not a Windows .NET course • You will NOT be required to be an expert on .NET • You will be required to be knowledgeable about it • History: • Open source, Java, Linux the WWW threatened MS • Especially Java was gaining widespread support amongst developers for its ease of use, productivity and heterogeneity • The Empire Strikes back = the .NET Framework

4. Benefits of .NET • Changes EVERYTHING • Takes all that was nice in Java and enhances it • End of DLL incompatibilities, DLL Hell, COM registry hell • Enter world of VM’s and Java like code (C#) including Garbage collection – BUT with easy support for legacy unmanaged code (e.g. C++ for speed) and COM • Performs much better than Java, and almost equivalent with Win32 C++ applications • Still only support Microsoft operating systems BUT • .NET and C# is ECMA standard: Mono (www.go-mono.org) for Linux is being developed. • IIOP.NET (http://iiop-net.sourceforge.net/index.html) for CORBA interop

5. Message Queuing COM+ (Transactions, Partitions, Object Pooling) IIS WMI .NET Framework Any language conforming to the Common Language Specification (CLS) may be used. 3 types of user interfaces: Web forms, Windows forms (Win32), Command Console Visual Basic C++ C# Perl JScript … XML Web Services User Interface ActiveX Data Objects For inter-process communications ADO.NET and XML CLR:runtime execution environment. Equlas JVM of Java. Microsoft Intermediate Language (MSIL) equals Java ByteCode Here we find the .NET Remoting libraries A collection of class libraries (over 9000) wraps Win32 like Java API .NET Framework Class Library Common Language Runtime Application services. E.g. IIS, Message Queuing etc. Win32 .NET Framework Other IL libraries Source code Intermediate Language Linked Program Executable Program Compiler Linker JIT-compiler

6. Strategies • Two .NET Remoting strategies: • Web services for inter-business purposes • Is heterogeneous across platforms and languages • Supported by the .NET compact framework • Relies primarily on HTTP/SOAP protocols, • May be adapted for any type of protocol • Heterogeneous • Is slow when used with HTTP/SOAP • .NET Remoting for intra-business purposes • Is only heterogeneous across CLS languages • Not supported by the .NET compact framework • Relies on either HTTP/SOAP or TCP/Binary protocols, • May be adapted for any type of protocol • Is fast when used with TCP/Binary • Only heterogeneity within .NET runtime • In many ways very similar to Java RMI in Java 5

7. Simplified .NET Remoting Architecture The Remoting System wraps most of the marshalling/unmarshalling work for you – like CORBA Using the classic Proxy pattern Channel: Takes a stream of data and transports it to another computer or process: Default: TcpChannel & HttpChannel

8. The Remoting Architecture Proxy created dynamically by the CLR. Creates a message to the server All server objects must be of type MarshalByRefObject or an descendant hereof Dispatch to server object Serializes the message into a stream (SOAP or binary) Deserializes the message Optional extra handling Writes the stream to the wire, e.g. TCP or HTTP Developers are free to implement new channels or replace sink elements

9. Remotable Objects in .NET Remoting • Marshal-by-reference objects • By-reference – no state is transferred • MarshalByRefObject • Corresponds to CORBA Interface IDL and Java RMI Remote objects (UnicastRemote objects) • Proxy created • Marshal-by-value objects • By-value – complete object is serialized and transferred • Implements ISerializable or decorated with Serializable Attribute [Serializable] • Very similar to Java RMI Serializable objects • Some similarity with CORBA valuetypes (Objects by Value)

10. Activation • All server objects needs to be activated before a client proxy may access it • Two types of activation • Server Activation (SAO) • Activated when first client request arrives at server • Singleton: only one server instance for all clients • Single-call: a new server object pr. client request • Lifetime is defined by server • Client Activation (CAO) • Activated by the client with the CreateInstance method on the Activator object • Server object only associated with creating client • Lifetime is controlled by client (using leases) • Very different semantics than CORBA & RMI – closer to Web services (application, session, request scope) especially SAO

11. Lifetime management • .NET Remoting uses leases for lifetime management • All server objects has a lifetime lease – a time-to-live • Lease manager • controls the server object leases • If expired – check all sponsors (clients) • performs garbage collection on server objects • In DCOM • reference counting & pinging • In CORBA • ORB vendor specific • Often implemented as “time since last request” • In Java RMI • uses leases (similar to .NET Remoting). Clients auto-update lease at 50% • Web services • Toolkit specific (HTTP primitives: Application, Session, Request) • Application scope = runs for-ever / singleton

12. Configuration • Configuration: • Need to inform runtime which servers are available and at which address (URL) • Two types of configuration • Programmatic (shown in example next) • Configuration file • Web.config (e.g. with IIS) or Machine.config

13. Deployment • Server objects may be deployed as: • Windows Form application • Windows Console application • Windows Service • Internet Information Server deployment • no need for a server bootstrapping application

14. Server Stub Generation Client Stub Generation Server Coding Client Coding Development Steps – Remoting vs. CORBA & Java RMI CORBA .NET Remoting Design J2SE JDK CORBA: IDL Interface Definition CLS Interface Start with Server Interface Coding: JAVA RMI: JAVA interface Implicit stub gen. CORBA: IDL Java RMI: rmic CLS (C# …) RMI: JAVA C++, Java … CLS (C# …) C++, Java … ORB Remoting Configuration with CLR rmiregistry Server Registration

15. Making the HelloWorld App • Using Microsoft Visual Studio .NET • may of course be done with .NET Framework alone • Make Client & Server solutions • Server: • IHelloWorld.cs interface • HelloWorld.cs class implementation • Server.cs class implementation for boot-strapping • Add Reference to assembly System.Runtime.Remoting • Client • Must add IHelloWorld.cs • Client.cs class implementation • Add Reference to assembly System.Runtime.Remoting

16. The IHelloWorld Interface The “IDL” of .NET Remoting – similar to Java RMI using System; namespace RemotingHelloServer { // IHelloWorld is the interface for the HelloWorld server class. // It is the interface that is shared across the Internet public interface IHelloWorld { string sayHello(string name); } }

17. HelloWorld Implementation Code using System; using System.Runtime.Remoting; namespace RemotingHelloServer { // HelloWorld is a server object that is available // "by-reference". It contains a constructor and a the // "sayHello" method taking a string parameter "name" public class HelloWorld : MarshalByRefObject, IHelloWorld { private string greeting; public HelloWorld() { greeting = "OOMI Christsmas greetings from the server to: "; } public string sayHello(string name) { return (greeting + name); } } } A remote object “by-reference” that implements the IHelloWorld interface Implementing the sayHello method Like in Java RMI (& CORBA) – we need to have an implementation of the interface

18. Server Code – Console Bootstrapping using System; using System.Runtime.Remoting; using System.Runtime.Remoting.Channels; using System.Runtime.Remoting.Channels.Tcp; namespace RemotingHelloServer { public class Server { [STAThread] static void Main(string[] args) { //Create a TCP channel TcpChannel theChannel = new TcpChannel(8085) /* Register the channel so that clients can * connect to the server */ ChannelServices.RegisterChannel(theChannel); //Register the service on the channel RemotingConfiguration.ApplicationName = "HelloWorld App"; RemotingConfiguration.RegisterWellKnownServiceType( typeof(HelloWorld), "HelloWorld App", WellKnownObjectMode.SingleCall); /*Start the server and keep it running so that clients * can connect to it. May be aborted by keypress */ System.Console.WriteLine("Press Enter to end this server process"); System.Console.Read(); } } } Like in Java RMI (& CORBA) – we need some bootstrapping code – a server process This may become a Windows NT service or a simple application, e.g. a console or Windows Form application Register the channel on port 8085 Register the object

19. Client Code – Console Bootstrapping … include all the Remoting stuff namespace RemotingHelloClient { public class Client { [STAThread] static void Main(string[] args) { TcpChannel theChannel = new TcpChannel(); ChannelServices.RegisterChannel(theChannel); /* Activate the server object. Activation will bring * the server object to life, and create a proxy * stub class of the HelloWorld. In fact, as this is a * server-activated application, the call to the * server is NOT performed now, but instead waits until the * first request. It is thus the server who performs the * activation. This is the "Lazy-activation pattern" known * from e.g. CORBA */ IHelloWorldhelloWorld = (IHelloWorld) Activator.GetObject( typeof(RemotingHelloServer.IHelloWorld), "tcp://localhost:8085/HelloWorld App"); System.Console.WriteLine("Please enter your name and press Enter"); string name = System.Console.ReadLine(); //Make the call string greeting = helloWorld.sayHello(name); System.Console.WriteLine("We recieved from server: "+greeting); System.Console.WriteLine("Press Enter to end"); System.Console.Read(); } } } Optional (may be done implicitly) Create Proxy Call via Proxy object

20. Configuration Strategi • Alternative to Programmatic strategi: • Use a Server Configuration file (Listener.exe.config) configuration> <system.runtime.remoting> <application> <service> <wellknown mode="Singleton" type="RemotableType, RemotableType" objectUri="RemotableType.rem" /> </service> <channels> <channel ref="http" port="8989"/> </channels> </application> </system.runtime.remoting> </configuration>

21. Server Side Config Bootstrap • Still need to implement: interface, MarshalByRef • But boostrapping is much simpler using System; using System.Runtime.Remoting; public class Listener { public static void Main() { RemotingConfiguration.Configure("Listener.exe.config", false); Console.WriteLine("Listening for requests. Press enter to exit..."); Console.ReadLine(); } }

22. Client Configuration Strategi • A Client Configuration file (Client.exe.config) <configuration> <system.runtime.remoting> <application> <client> <wellknown type="RemotableType, RemotableType" url="http://localhost:8989/RemotableType.rem" /> </client> </application> </system.runtime.remoting> </configuration>

23. Client Side Config Load + Proxy • Still need to implement: interface, MarshalByRef • Generating dynamic proxy stub is simpler (VB.NET) Imports System Imports System.Runtime.Remoting Public Shared Sub Main() RemotingConfiguration.Configure(“Client.exe.config") Dim remoteObject As New RemotableType() Console.WriteLine(remoteObject.SayHello()) End Sub 'Main

24. Windows Communication Foundation (Kursorisk) • Windows Vista => .NET Framework 3.0 • Also for Windows XP and 2003 Server • Unified Service-Oriented Programming Model • Replaces / Suplements • .NET Remoting • DCOM • ASP.NET Web services • MSMQ (Queued Messaging) • .NET Enterprise Services • Protocol Neutrality and Flexibility http://msdn.microsoft.com/library/default.asp?url=/library/en-us/dnlong/html/wcfroadmap.asp http://msdn.microsoft.com/library/default.asp?url=/library/en-us/dnlong/html/wcfarch.asp

25. Defining the Contract using System.ServiceModel; //a WCF contract defined using an interface [ServiceContract] public interface IMath { [OperationContract] int Add(int x, int y); } //the service class implements the interface public class MathService : IMath { public int Add(int x, int y) { return x + y; } }

26. Implementing the Service public class WCFServiceApp { public void DefineEndpointProgrammable() { //create a service host for MathService ServiceHost sh = new ServiceHost(typeof(MathService)); //use the AddEndpoint helper method to //create the ServiceEndpoint and add it //to the ServiceDescription sh.AddServiceEndpoint( typeof(IMath), //contract type new WSHttpBinding(), //one of the built-in bindings "http://localhost/MathService/Ep1"); //the endpoint's address //create and open the service runtime sh.Open(); } public void DefineEndpointInConfig() { //create a service host for MathService ServiceHost sh = new ServiceHost (typeof(MathService)); //create and open the service runtime sh.Open(); } } Create the Service Endpoint Programmatically Create the Service Endpoint Using a Configuration File (see next slide)

27. Configuration File <!-- configuration file used by above code --> <configuration xmlns="http://schemas.microsoft.com/.NetConfiguration/v2.0"> <system.serviceModel> <services> <!-- service element references the service type --> <service type="MathService"> <!-- endpoint element defines the ABC's of the endpoint --> <endpoint address="http://localhost/MathService/Ep1" binding="wsHttpBinding" contract="IMath"/> </service> </services> </system.serviceModel> </configuration>

28. Implementing the Client Using Static Proxy //this class is generated by svcutil.exe //from the service's metadata //generated config is not shown here public class MathProxy : IMath { ... } public class WCFClientApp { public void SendMessageToEndpoint() { //this uses a proxy class that was //created by svcutil.exe from the service's metadata MathProxy proxy = new MathProxy(); int result = proxy.Add(35, 7); }

29. Implementing the Client Using Dynamic Proxy public class WCFClientApp { public void SendMessageToEndpointUsingChannel() { //this uses ChannelFactory to create the channel //you must specify the address, the binding and //the contract type (IMath) ChannelFactory<IMath> factory=new ChannelFactory<IMath>( new WSHttpBinding(), new EndpointAddress("http://localhost/MathService/Ep1")); IMath channel=factory.CreateChannel(); int result=channel.Add(35,7); factory.Close(); }

30. Plenum Discussion • Use 5 minutes in your groups: • Differences with CORBA? • Strength over CORBA? • Weaknesses compared to CORBA? • Plenum: 5 minutes discussion of findings

31. Læringsmål Alignment I kan nu definere og beskrive Grundlæggende .NET Remoting principper Når kurset er færdigt forventes den studerende at kunne: • Definere, beskrive og sammenligneforskellige typer af objektorienterede middleware frameworks til apparater og computere, med primær fokus på CORBA og sekundært .NET Remoting teknologierne, herunder fordele og ulemper forbundet med de forskellige teknologier • Definere og beskrive principper omkring transparens og heterogenitet i relation til middlewareteknologier • Definere og beskrive gængse teorier, metoder og retningslinier indenfor det objektorienterede middleware paradigme og anvende disse til at designe effektive distribuerede systemer • Designe og konstruere et distribueret system der gør brug af CORBA og .NET Remoting teknologierne med tilhørende værktøjssupport Stubbe, dynamisk Proxy, ”IDL”, Retningslinier, transp., hetero. manglende IDCl compiler, referencer Grundlæggende forståelse For hvad der skal til af CORBA Teknologier, og værktøjer MANGLER: praktisk arbejde med .NET Remoting -> se øvelser