Middleware Technologies

Sub Code : MC1754                                                Sub Name: Middleware Technologies

     Unit – I

PART -A

Two Mark Questions

1. What is Client/Server Computing?

Client/Server Computing means scrapping every mainframe that can’t fit on the desktop and the demise of host-centric computing and also unleashing a new bread of “born-again” networked mainframes that will bring every PC in the enterprise back to the fold. This computing provides

-         Open & Flexible  Environment

-         Allowing to mix and match Services

-         Client application can run in any platform

2. What is Client/Server?

Client/Server is separated logical entities i.e. software programs that work together over a network to accomplish a task. The client and server logical entities are called as separate program units. The Client first initiates the communication by passing request to server. The server gets the request and produces the response   and send back to the client over on the network.

3. What are the basic characteristics of Client/Server System?

·        Service                     

·        Shared Resources

·        Mix-and-Match

·        Encapsulation of services

·        Scalability

·        Asymmetrical Protocols

·        Transparency of location

·        Integrity

·        Distributed Across a network

4. List out types of servers?

v     File Server

v     Database Server

v     Groupware Server

v     Object Server

v     Transaction Server

v     Web Server

5.  Write about File Server.

A Fileserver consists of large amount of files that may be documents, images, engineering drawings and other large data objects. File Servers are useful for sharing files across a network. They are indispensable for creating shared repositories of all types of files.

6. Write about Database Server.

A Database server maintains databases and uses its own processing power to find the requested data from database. The Client passes SQL requests as messages to the database server. The requests of each SQL command are returned over the network. The result is a much more efficient use of distributed processing power.

7. Write about Groupware Server and give an example.

Groupware addresses the management of semi-structured information such as text, image, mail, bulletin boards and the flow of work. This Client/Server System provides direct communication between clients. Here applications are created by using a scripting language and form-based interfaces.

Example: Lotus Notes

   8. Write about Object Servers and give an example.

The Client/Server applications are written as a set of communicating Objects. Client objects communicate with server objects using an instance of that Object Request Broker (ORB). The ORB locates an instance of that object server class, invokes the requested method, and returns the results to the client objects. Server objects must provide supports for concurrency and sharing

9. Write about Web Servers and give an Example.

This type of servers is intergalactic Client/Server application. This consists of thin, portable, “Universal” clients that talk to super fast servers. The web server returns documents when clients ask for them by name. The clients and servers communicate using an RPC-like protocol called HTTP.

10. What is Middleware?

            Middleware is software that acts as an interface between client and server. This is implemented in 3-tier Architecture of client/server system. This Middleware provides a way to interact the server for the client. Its the glue that lets a client obtain a service from the server. Depends upon the service of Middleware, it classified as

1.      General Middleware 2. Service-specific Middleware

11. What is General Middleware?

            General Middleware is the subtract for most client/server interactions. It includes the Communication stacks, distributed directories, authentication Services, Network time, RPC and queuing services. This type also includes the network OS extensions such as distributed file and print services.

12. What is Service-Specific Middleware?

            Service-specific middleware is needed to accomplish a particular client/server type of service.

This includes:

 * Database-specific Middleware (ODBC, EDA/SQL)

 * OLTP-specific Middleware (RPC,X/Open’s TxRPC)

 * Groupware-specific Middleware (SMTP, Lotus Notes Calls)           

 * Object-specific Middleware (CORBA, DCOM)

 * Internet-specific Middleware ( HTTP, S-HTTP ,SSL)

 * System Management Specific Middleware (SNMP, ORB)

13.  What is Fat Server model?

            The Fat Server model places more function on the server Fat server applications are easier to manage and deploy on the network because most of the code runs on the servers. Fat servers try to minimize network interchanges by creating more abstract levels of services.

 Examples: Groupware Server, Transaction Server, Web Server.

16.   What is Fat Client model?

            Fat Clients are the more traditional form of Client/Server. The bulk of the application runs on the client side of the equation. Fat Clients are used for decision support and personal software. They provide flexibility and opportunities for creating front-end tools that let end-users create their own application.

Examples: Database Server, File Server

17. What are the Key Technologies are needed by the Client/Server System?

·        Rich Transaction Processing

·        Roaming Agents

·        Rich data Management

·        Intelligent self-managing entities

·        Intelligent Middleware.

18. What are the types of Building Blocks?

·        The  Client  Building Block

·        The  Server  Building Block

·        The Middleware  Building Block

19. Write about Client Building Block.

The Client building block runs the client side of the application. It runs on an Operating System (OS) that provides a GUI or OOUI and that can access distributed services. The Client also runs a component of the Distributed System Management (DSM) elements.  The requests are gathered by using this client side application from client user.

20. Write about   Server Building Block

The server application runs on top of some shrink-wrapped server software package. The contending server platforms for creating the next generation of client/server applications are SQL database servers, TP Monitors, Groupware servers, Object servers and Web Server.

21. Write about Middleware Building Block.

It runs on both the client and server sides of an application. This building block is broken into 3 categories:

§         Transport Stack

§         Network Operating System

§         Service- Specific Middleware

22. What is Peer-to-Peer Communication?

            The term “Peer-to-Peer “indicates that the two sides of a communication link use the same protocol interface to conduct a networked conversation. Any computer can initiate a conversation with any other computer. The protocol is symmetrical and it is sometimes called “Program-to-Program”. The peer-to-peer tends to “close to the wire” in the sense that it does not fully mask the underlying network from the programmer.

23. What is RPC?

RPC stands for Remote Procedure Calls and it also invoke the process of server.

This invoked program runs across the wire in a different resource domain. A Client process calls function on a remote server and suspends itself until it gets back the results. Parameters are passed like in any ordinary procedure.  The RPC, like an ordinary procedure, is synchronous. The RPC run-time software collects values for the parameters ,forms a message , and sends it to the remote server. The server receives the request, unpacks the parameters, calls the procedure and sends the reply back to the client.

24. Write about IPX/SPX. What is the purpose of IPX/SPX protocol in Netware?

            IPX/SPX is a Netware’s native stack. IPX/SPX is an implementation of the Xerox Network Services (XNS) transport and network protocol.  This is a cleaner version of TCP/IP protocol. So this is required by LAN enterprises. The IPX/SPX network layer is provided by the Internet Packet Exchange (IPX) protocol. This provides unreliable services with connection oriented manner. So the SPX is used on the top of IPX to achieve the reliable service with datagram service.

25. Write the advantages and disadvantages of NetBEUI.

Advantages are:

·        Datagram Service

·        Connection – oriented Service

·        Dynamic Naming Service

Disadvantages are:

·        Lack of network layer

·        Lack of Security layer

26. How the NetBIOS services are archived?

            The NetBIOS services are provided through a set of commands, specified in a structure called Network Control Block (NCB). The structure also contains the parameters associated with the command and the fields in which NetBIOS will return information to the program. A command can be issued in either wait or no-wait mode.  In wait mode, the requesting thread is blocked until the command completes. In the no-wait mode, control is returned to the calling thread at the earliest time possible, usually before the command completes.  When the command completes, the NetBIOS DLL places a return code in the NCB.

           

PART - B

16 Marks Questions

1. Discuss about Client/Server Concepts. 
2. (i) Discuss Client/Server System basic Characteristics .

(ii) List out Server types and briefly explain each server.

3. What is Middleware? Briefly explain each type of Middleware?
4. (i) Discuss about Fat Server Model and Fat Client Model. 

(ii) Discuss about 2-tier Client/Server System versus 3-tier Client/Server System.

(ii) What is Intergalactic Client/Server? What are the key technologies are needed for Client/Server System?

5. What are the basic building blocks in Client/Server System? And Explain each

Situations of building blocks arrangements. 

6. Discuss about each type of building blocks. (or) Discuss about  Inside The    

Building blocks.

7. Explain briefly about Peer-to-peer Communications
8. (i) Explain briefly about Socket.
9. (i) Explain briefly about NetBIOS and NetBEUI.
10. (ii) Explain briefly about Netware (pg. 119) and Named Pipes.
11. Explain briefly   Remote Procedure Calls (RPC).
12. (i)Explain about Message Oriented Middleware (MOM).

(ii) Comparing MOM and RPC.