With an object server, the Client/Server application is written as a set of communicating objects. Client object communicate with server objects using an Object Request Broker (ORB). The client invokes a method on a remote object. The ORB locates an instance of that object server class, invokes the requested method and returns the results to the client object. Server objects must provide support for concurrency and sharing. The ORB brings it all together.
2. What is a Transaction server?
With a transaction server, the client invokes remote procedures that reside on the server with an SQL database engine. These remote procedures on the server execute a group of SQL statements. The network exchange consists of a single request/reply message. The SQL statements either all succeed or fail as a unit.
With a database server, the client passes SQL requests as messages to the database server. The results of each SQL command are returned over the network. The server uses its own processing power to find the request data instead of passing all the records back to the client and then getting it find its own data. The result is a much more efficient use of distributed processing power. It is also known as SQL engine.
4. What are the most typical functional units of the Client/Server applications?
User interface
Business Logic and
Shared data.
5. What are all the Extended services provided by the OS?
Ubiquitous communications
Network OS extension
Binary large objects (BLOBs)
Global directories and Network yellow pages
Authentication and Authorization services
System management
Network time
Database and transaction services
Internet services
Object- oriented services
6. What are Triggers and Rules?
Triggers are special user defined actions usually in the form of stored procedures, that are automatically invoked by the server based on data related events. It can perform complex actions and can use the full power of procedural languages.
A rule is a special type of trigger that is used to perform simple checks on data.
7. What is meant by Transparency?
Transparency really means hiding the network and its servers from the users and even the application programmers.
8. What are TP-Lite and TP-Heavy Monitors?
TP-Lite is simply the integration of TP Monitor functions in the database engines.
TP-Heavy are TP Monitors which supports the Client/Server architecture and allow PC to initiate some very complex multiserver transaction from the desktop.
9. What are the two types of OLTP?
TP lite, based on stored procedures. TP heavy, based on the TP monitors.
This new model of Client/Server consists of thin, portable, "universal" clients that talk to super fat servers. In the simplest form, a web server returns documents when clients ask for them by name. The clients and server communicate using an RPC-like protocol called HTTP.
These are fully-loaded machines which includes multiprocessors, high-speed disk arrays for interview I/O and fault tolerant features.
There is no commonly accepted definition for a TP monitor. According to Jeri Edwards' a TP Monitor is "an OS for transaction processing".
They were originally introduced to run classes of applications that could service hundreds and sometimes thousands of clients. TP Monitors provide an OS - on top of existing OS - that connects in real time these thousands of humans with a pool of shared server processes.
14. What is meant by Asymmetrical protocols?
There is a many-to-one relationship between clients and server. Clients always initiate the dialog by requesting a service. Servers are passively awaiting for requests from clients.
15. What are the types of Transparencies?
The types of transparencies the NOS middle ware is expected to provide are:-
Location transparency
Namespace transparency
Logon transparency
Replication transparency
Local/Remote access transparency
Distributed time transparency
Failure transparency and
Administration transparency.
16. What is the difference between trigger and rule?
The triggers are called implicitly by database generated events, while stored procedures are called explicitly by client applications.
17. What are called Transactions?
The grouped SQL statements are called Transactions (or) A transaction is a collection of actions embused with ACID properties.
18. What are the building blocks of Client/Server?
The client
The server and
Middleware.
19. Explain the building blocks of Client/Server?
The client side building block runs the client side of the application.
The server side building block runs the server side of the application.
Transport stack
Network OS
Service-specific middleware.
21. What are all the Base services provided by the OS?
Task preemption
Task priority
Semaphores
Interprocess communications (IPC)
Local/Remote Interprocess communication
Threads
Intertask protection
Multiuser
High performance file system
Efficient memory management and
Dynamically linked Run-time extensions.
22. What are the roles of SQL?
SQL is an interactive query language for ad hoc database queries.
SQL is a database programming language.
SQL is a data definition and data administration language.
SQL is the language of networked database servers
SQL helps protect the data in a multi-user networked environment.
Because of these multifacted roles it plays, physicists might call SQL as "The grand unified theory of database".
23. What is Structured Query Langauge (SQL)?
SQL is a powerful set-oriented language which was developed by IBM research for the databases that adhere to the relational model. It consists of a short list of powerful, yet highly flexible, commands that can be used to manipulate information collected in tables. Through SQL, we can manipulate and control sets of records at a time.
24. What are the characteristics of Client/Server?
Service
Shared resources
Asymmetrical protocols
Transparency of location
Mix-and-match
Message based exchanges
Encapsulation of services
Scalability
Integrity
Client/Server computing is the ultimate "Open platform". It gives the freedom to mix-and-match components of almost any level. Clients and servers are loosely coupled systems that interact through a message-passing mechanism.
25. What is Remote Procedure Call (RPC)?
RPC hides the intricacies of the network by using the ordinary procedure call mechanism familiar to every programmer. A client process calls a 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 process that issues the call waits until it gets the results.
Under the covers, 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, unpack the parameters, calls the procedures, and sends the reply back to the client. It is a telephone-like metaphor.
