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.Net Remoting

.Net Remoting. CS-795 Security In Distributed Systems Using .Net Summer 2007 Old Dominion University. Remoting Introduction. The process of programs or components interacting across certain boundaries either different processes or machines

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.Net Remoting

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  1. .Net Remoting CS-795 Security In Distributed Systems Using .Net Summer 2007 Old Dominion University

  2. Remoting Introduction • The process of programs or components interacting across certain boundaries either different processes or machines • Developer Speak - Remoting allows you to pass objects or values across servers in different domains using several different protocols.

  3. Remoting Benefits • Centralized Business Logic • Physical Separation of Layers • Secure Third Party Access

  4. Why use .Net Remoting ? • Objects in different .NET application domains cannot access each other directly • two apps running on same machine even cannot talk to each other without a third party (text files, logs etc) • Enables client code in one application domain to call methods/properties of objects running in another application domain. • .Net analogy to DCOM

  5. .Net Remoting Benefits • Multiple transfer mechanisms – HTTP/TCP • If there is no web server running – put traffic on port 80 • Multiple encodings – SOAP/ Binary (your own-serialization) • .NET Remoting is more flexible (more activation and deployment options) • .NET Remoting is customizable (you can add logging or other features)

  6. .Net Remoting Benefits • .Net Remoting enables you to work with stateful objects • Interface description does not have to be manually coded in any way, as metadata can be extracted from running servers, or from any .Net assembly • One of the major benefits is that it’s centralized around well-known and well-defined standards like HTTP and is directly tied to the .Net Framework

  7. .Net Remoting Basics Client Server Server-Side Object Proxies Dispatcher Formatter Formatter Transport Channel Transport Channel Fig. The .Net Remoting Architecture

  8. .Net Remoting Basics • Different Ways of defining interfaces: • Shared Assembly • Shared Interface or Base Objects • Generated Metadata Assembly (SoapSuds) • Serialization of Data: • Encoding/Decoding of Objects natively supported • Just need to mark such objects with [Serializable] attribute or implement the interface ISerializable • Lifetime Management • Open network connection between client-server • Combined reference counting and pinging mechanisms • Objects get lifetime when created (reset: time-to-live) • Sponsor registered with a server-side object • Multiserver/Multiclient • .Net automatically keeps track of remote object’s origin

  9. .Net Remoting Basics • 2 very different kinds of Objects • Passed by Reference • These objects live on server • Only ObjRef will be passed around • The client usually may not have compiled objects in one of its assemblies, instead only a interface or Base class is available to client • Proxy Object takes care of all remoting tasks

  10. .Net Remoting Basics • 2 very different kinds of Objects • Passed by Value • These objects will be passed over remoting boundaries • Serialized into a string or binary representation and restored as a copy on other side of comm. channel • Each one has its own copy and run independently • Client has to have the compiled object in one of its assemblies • Must support Serialization • [Serializable] class-level attribute or ISerializable interface

  11. First Remoting Application • ICustomerManager: Remote Interface • Customer: Data Object • Server: Implements ICustomerManager interface • Client: Consuming entity • Let us see some code …

  12. MarshalByRefObjects • Categorized into 2 groups: • Server-activated objects (SAOs) • Client-activated objects (CAOs) • SAO: • Comparable to classic stateless Web Services • No message travels to server on reference request by a client • Only when methods are called on this remote reference will the server be notified • Can be either Singleton / SingleCall • How SAO (Singleton/SingleCall) works ? … code helps

  13. MarshalByRefObjects (CAO) • CAO: • An instance of specified class created when • A creation request on the client is encountered using new operator or Activator.CreateInstance() method • An activation message sent to the server • Are stateful objects • Will store state information from one method call to the other

  14. MarshalByRefObjects (CAO) • Cannot use shared interface or assemblies • Have to ship the complied objects to the clients or use SoapSuds to extract metadata out of a running server or a server-side implementation assembly • SoapSuds suggested not be used anymore for .Net to .Net distributed applications • Instead we use a factory design pattern • In this a SAO provides methods to return new instances of the CAO • How CAO (factory design pattern) works ? … code helps

  15. Factory Design Pattern using System; Namespace FactoryDesignPattern { class MyClass {} class MyFactory { public MyClass GetNewInstance() { return new MyClass(); } }

  16. Factory Design Pattern class MyClient { static void Main(string[] args) { //creating using “new” MyClass obj1 = new MyClass(); //creating using a factory MyFactory fac = new MyFactory(); MyClass obj2 = fac.GetNewInstance(); } } }

  17. Managing Life Time of an Object • Lease-based object lifetime • Each server-object is associated with a lease on creation • Lease has time-to-live counter, decremented in certain intervals • In addition, a defined amount of time is added on every method call a client places on remote object • Upon reaching zero time, framework looks for a sponsor registered with the lease.

  18. Managing Life Time of an Object • Lease-based object lifetime • A sponsor is an object running on sever itself, client or any machine reachable via a network • An object subject to garbage collection if • A sponsor decides that the lease will not be renewed • Framework unable to contact any registered sponsors • If a client references time out object, an exception is thrown • System.Runtime.Remoting.Lifetime class

  19. Types of Invocation • Synchronous Calls • Client waits until server finishes processing the request • Asynchronous Calls • Delegates work • One-Way Calls • Framework does not guarantee their execution • Method cannot have return values or out parameters • No exception thrown even if server is down or the method call is malformed • Used in uncritical logging or tracing facilities

  20. .Net Remoting vs Web Services

  21. References • Advanced .Net Remoting – Ingo Rammer & Mario • http://www.thinktecture.com/ • Building Web Services with .Net Remoting and ASP.Net • Group of Authors • .NET Remoting Versus Web Services • http://www.developer.com/net/net/article.php/11087_2201701_1

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