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.NET REMOTING. CertSIG Tom Perkins. FUNDAMENTALS. Distributed Applications. Process B. Objects can communicate across process boundaries Objects may be on same computer, different computers, or Internet Heterogeneous architectures allowed

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net remoting



Tom Perkins

distributed applications
Distributed Applications

Process B

  • Objects can communicate across process boundaries
  • Objects may be on same computer, different computers, or Internet
  • Heterogeneous architectures allowed
  • Some processes can run even though others busy or have failed
  • Application divided into tiers (layers) – gives increased flexibility and scalability

Process A

Process C

process boundaries
Process Boundaries
  • Good News …
  • Windows creates “process boundary” to isolate processes
  • Keeps one process from affecting others
  • Each process has its own
    • virtual address space
    • Executable code
    • Data
  • One process cannot access code or data of another process
  • If process crashes it doesn’t affect others

Process B

Process A

Bad News …

Takes a lot of resources to create, monitor, and terminate processes

Switching processes is expensive

Many apps have many short-lived processes

application domains
Application Domains


  • Provides managed execution
  • Services:
    • Cross-language integration
    • Code access security
    • Object lifetime management
    • Debugging
    • Profiling support
  • Application can run in CLR in application domain
  • Smallest execution unit in .NET
  • Class System.AppDomain
  • Several app domains can run in a Windows process
  • App domain boundary similar to process boundary, but much cheaper
  • Can run multiple apps in same Windows process

Process A

Application Domain


Application Domain


3 ways to develop distributed applications
3 Ways to develop Distributed Applications
  • Standalone listeners
  • Custom protocol handlers
  • Requires good understanding of network programming

System.Net Namespace

  • Classes in this chapter
  • Allows communication between objects in different app domains
  • May be on separate computers
  • Simple way for processes to communicate
  • Key characteristics: flexibility and extensibility



  • Classes make up ASP.NET Web Services
  • Objects exchange messages in HTML and SOAP
  • Key characteristics: simplicity and interoperability with other systems

System.web services



what is net remoting
What is .NET Remoting?
  • .Net Remoting allows objects in different application domains to talk to one another
  • It handles the details of network communication transparently
what about this business of no direct calls across application domain boundaries
What about this business of no direct calls across application domain boundaries?
  • Remoting uses indirect approach
  • Creates proxy objects
net remoting architecture
.Net Remoting Architecture

Client object

Server Object



Remoting System

Remoting System

Client App Domain

Server App Domain

  • Process of packaging and sending method calls among objects
  • Uses serialization and deserialization
remotable objects
Remotable Objects
  • Definition – objects that can be marshalled across application domains
  • All other objects – non-remotable objects
  • Two types of Remotable Objects
    • Marshal-by-value (MBV)
      • Copied from server domain to client app domain
    • Marshal-by-reference (MBR)
      • Uses proxy to access objects on client side
      • Clients hold just a reference to these objects
marshal by value objects
Marshal-by-Value Objects

Faster performance

Fewer network roundtrips

Large objects slow to move

Doesn’t run in (better) server environment


Object resides here

Client invokes a method on MBV object



Object is serialized, transferred over network,restored on client as exact copy


MBV object available on client;

No proxy, no marshalling

Create by declaring class serializable


Public class MyMBVObject

Server App Domain

Client App Domain

marshal by reference objects
Marshal-by-Reference Objects

Increases number of network roundtrips

Use when objects are large

Or functionality available only on server


Object always resides, executes here

Client invokes a method on object




Local proxy holds reference to object

Server App Domain

Client App Domain

public class MyMBRObject : MarshalByRefObject

  • Objects that transport messages across application boundaries (computers, etc)
  • When client calls method on server, info transferred through channel
  • Info back through same channel
  • Channels must be registered before they can be used
more about channels
More about Channels
  • Channel has 2 endpoints
  • Receiving end (server) listens to particular protocol through specified port number
  • Sending end (client) sends info using protocol and port number specified by server
  • Receiving end  must implement IChannelReceiver Interface
  • Sending end  must implement IChannelSender Interface
  • Protocols
    • HTTP
    • TCP
  • Defn- objects used to serialize and deserialize data into messages before they are transmitted over a channel
  • 2 Formatters
    • SOAP – SOAPFormatter class
    • Binary – BinaryFormatter class
  • Defaults
    • HTTP Channel SOAP formatter
    • TCP Channel Binary formatter
remote object activation
Remote Object Activation
  • Only MBR objects can be activated remotely
  • 2 Categories of Activate objects
    • Server-activated objects
    • Client-activated objects

Server object

Client object

server activated objects soas
Server-activated Objects (SOAs)
  • Object Lifetime controlled directly by server
  • Remote object instantiated only when client calls a method on proxy object

Client object

Server Object

Proxy object

This guy controls its own lifetime

2 activation modes for soas
2 Activation Modes for SOAs
  • Single-Call activation
    • Object instantiated only for purpose of fulfilling one client request
    • .NET then deletes and reclaims memory
  • Singleton Activation mode
    • At most one remote object, regardless of how may clients may be using it
    • State can be maintained
    • Lifetime Lease determines its lifetime
when to use
When to use
  • Single-Call activation
    • When it doesn’t cost much to create an object
    • No object state required
    • Server needs to support large number of requests for object
    • Load balancing environment
    • (retrieve inventory level for an item, display shipment info, etc)
  • Singleton Activation
    • Use when it costs a lot to create an object
    • State required over a long period of time
    • Several clients need to work on the shared state
    • (Chat server – multiple people talk to same remote object and share data with one another)
client activated objects caos
Client-Activated Objects (CAOs)

Client object

  • Lifetime is controlled by the client
  • CAOs are instantiated on server as soon as the client requests the object to be created.
  • Object creation is not delayed until first method is called by client.

Server Object

Proxy object

This guy controls this guy’s lifetime.

cao activation
CAO Activation

Client object

Server Object

3. Server creates object

1. Client attempts to create an instance of the server object.

5. Client uses ObjRef object to build proxy


2. Activation request sent to remote server


Remoting System

Remoting System

4. Server return ObjRef object to client – info to build proxy object

Client App Domain

Server App Domain

cao characteristics
CAO Characteristics
  • Serves only client responsible for its creation
  • Doesn’t get discarded with each request
  • Can maintain state with client it is serving
  • Unlike Singleton CAO’s, different CAOs cannot share a common state.
when to use caos
When to Use CAOs
  • Clients want to maintain a private session with the remote object
  • Clients want to have control over how the object is created and how long it should live.
  • Example: a complex purchase order involving many roundtrips and clients want to maintain their own private state with the remote object
comparing object activation techniques
Comparing Object Activation Techniques

Maximum scalability; remote object uses resources for min time; server can handle many clients

Maximum flexibility; you have complete control over remote object construction and lifetime

lifetime leases
Lifetime Leases
  • Definition – the period of time a particular object will be in memory before deletion and garbage collection
  • Used by Singleton SAOs and CAOs
  • Object must implement Ilease interface in the System.Runtime.Remoting.Lifetime namespace
demo 1 create a remotable class
DEMO – 1.Create a Remotable class
  • Must inherit from MarshalByRefObject class.
  • This demo creates DbConnect class (will produce a remote server object)
  • Purpose: connects to a SQL Server database
  • Allows you to execute a SELECT statement to return a dataset – ExecuteQuery() method on the server object.
  • Walkthru, then class is in DLL (bin\Debug)
  • Still need to connect to Remoting Framework

Remotable class

Server object

Client object




server program
Server Program
  • Connects to .Net Remoting Framework
  • Listens to the client request
  • Instantiates the remote object
  • Invokes calls on remote object as requested by client

Server Program

Listens to client requests

Remote object

creating a server activated object sao
Creating a Server-Activated Object (SAO)

Remotable class



Remoting Server Program


Activation requests


1. create server channel – listens on particular port for activation requests from other application domains

TcpServerChannel channel = new TcpServerChannel(1234) // port 1234

2. Register the channel with .Net Remoting

3 Register the remotable class


typeof(dbConnect), // type of class

“DbConnect”, // URI of remotable class

WellKnownObject Mode.SingleCall)

// activation mode – c.b. Singleton

Remote object can be accessed through all registered channels

demo 2 create a server activated object singlecall
DEMO – 2. Create a Server-Activated Object (SingleCall)
  • Exposes the remotable class through the remoting framework
  • Long running process
    • No interface
    • Listens for incoming client requests on a channel
  • This example uses a Console application
  • (Should be a Windows service or IIS)
  • Walkthru – StepByStep3_2
  • Creates a remoting host that listens on port 1234
demo 3 instantiate and invoke a server activated object
DEMO – 3. Instantiate and Invoke a Server-Activated Object
  • We’re building a Remoting Client
  • We want to send messages to Remoting Server to activate the Remote object.
  • Steps
    • Create and register a client channel to send messages to server; type s.b. compatible (TCP or HTTP)
    • Register the remotable class in the client’s app domain.
    • Instantiate the server object

DbConnect dbc = new DbConnect();

stepbystep3 3
  • Windows application
  • Accepts SQL SELECT string from user
  • Passes it to remotable object
  • Returned rows are displayed in datagrid