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Presentation 23 .NET Remoting Introduced Outline • • • • • • • .NET Remoting strategies Architecture Remoting object types Activation Lifetime Deployment Example application High-level introduction only! Slide 2 af 16 Ingeniørhøjskolen i Århus .NET Framework Remoting 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, but 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, but 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 Slide 3 af 16 Ingeniørhøjskolen i Århus Simplified .NET Remoting Architecture The Remoting System wraps most of the marshalling/unmarshalling work for you – like Java/CORBA Using the classic Proxy pattern Channel: Takes a stream of data and transports it to another computer or process: Default: TcpChannel & HttpChannel Slide 4 af 16 Ingeniørhøjskolen i Århus 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 Slide 5 af 16 Ingeniørhøjskolen i Århus 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) Slide 6 af 16 Ingeniørhøjskolen i Århus 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 Slide 7 af 16 Ingeniørhøjskolen i Århus 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 Slide 8 af 16 Ingeniørhøjskolen i Århus 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 Slide 9 af 16 Ingeniørhøjskolen i Århus 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 Slide 10 af 16 Ingeniørhøjskolen i Århus Development Steps – Remoting vs. CORBA & Java RMI CORBA .NET Remoting Design J2SE JDK Start with Server Interface Coding: JAVA Server Stub Generation Interface Definition CORBA: IDL CLS Interface RMI: JAVA interface Implicit stub gen. CORBA: IDL Client Stub Generation Java RMI: rmic CLS (C# …) C++, Java … Server Coding Client Coding RMI: JAVA CLS (C# …) C++, Java … Remoting Configuration with CLR Server Registration ORB rmiregistry Slide 11 af 16 Ingeniørhøjskolen i Århus Making the HelloWorld application • 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 Slide 12 af 16 Ingeniørhøjskolen i Århus 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); } } Slide 13 af 16 Ingeniørhøjskolen i Århus 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; A remote object “by-reference” that implements the IHelloWorld interface public HelloWorld() { greeting = "OOMI Christmas greetings from the server to: "; } public string sayHello(string name) { return (greeting + name); } Implementing the sayHello method } } Like in Java RMI (& CORBA) – we need to have an implementation of the interface Slide 14 af 16 Ingeniørhøjskolen i Århus Server code – Console bootstrapping using System; Like in Java RMI (& CORBA) – we need some using System.Runtime.Remoting; bootstrapping code – a server process using System.Runtime.Remoting.Channels; using System.Runtime.Remoting.Channels.Tcp; namespace RemotingHelloServer This may become a Windows NT service or a simple { application, e.g. a console or Windows Form application public class Server { [STAThread] static void Main(string[] args) { //Create a TCP channel Register the channel TcpChannel theChannel = new TcpChannel(8085) on port 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); Register the object /*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(); } } } Slide 15 af 16 Ingeniørhøjskolen i Århus 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); Optional (may be done implicitly) /* 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 */ IHelloWorld helloWorld = (IHelloWorld) Activator.GetObject( typeof(RemotingHelloServer.IHelloWorld), "tcp://localhost:8085/HelloWorld App"); Create Proxy 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(); Call via Proxy object } } } Slide 16 af 16 Ingeniørhøjskolen i Århus