There are two main classes of servers, iterative and concurrent. An iterative server iterates through each client, handling it one at a time. A concurrent server handles multiple clients at the same time. The simplest technique for a concurrent server is to call the fork function, creating one child process for each client.
What is an iterative server?
Iterative servers are fairly simple and are suitable for transactions that do not last long. However, if the transaction takes more time, queues can build up quickly. In Figure 1 , once Client A starts a transaction with the server, Client B cannot make a call until A has finished.
What is iterative or concurrent in IBM IMS and CICS?
IBM defines two models for accessing server applications in CICS and IMS. In both models, there is a TCP/IP connection Listener and a Server aspect to the total application. The manner in which the Listener and Server portions of the application are implemented determines whether the model is Iterative or Concurrent.
How to write a concurrent server under Unix?
The server must be capable of handling multiple clients at the same time. The simplest way to write a concurrent server under Unix is to fork a child process to handle each client. Following program shows the typical concurrent server.
What is the difference between concurrent access and iterative access?
The Concurrent access model requires the use of a Transaction Request Message (TRM); the Iterative model does not. The TRM is a formatted data record that identifies the IMS or CICS transaction program (TP) to be invoked and its characteristics.
What is meant by iterative server?
An iterative server processes requests from clients in a serial manner; one connection is served and responded to before the server accepts a new client connection.
How does a concurrent server work?
A concurrent server accepts a client connection, delegates the connection to a child process of some kind, and immediately signals its availability to receive the next client connection.
What is iterative connectionless server?
Connectionless iterative server: receives a request packet from UDP, processes the request, gives response to the UDP to send to the client, • Packets are stored in a queue, and processed in order of arrival.
What is connection-oriented concurrent server?
Concurrent, connection-oriented server: It is the most general type of server because it offers reliable transport (i.e., it can be used across a wide area Internet) as well as the ability to handle multiple requests concurrently.
How do I make my server concurrent?
This is the simplest technique for creating a concurrent server. Whenever a new client connects to the server, a fork() call is executed making a new child process for each new client. Multi-Threading achieves a concurrent server using a single processed program.
How many clients can concurrent server manage?
On the TCP level the tuple (source ip, source port, destination ip, destination port) must be unique for each simultaneous connection. That means a single client cannot open more than 65535 simultaneous connections to a single server. But a server can (theoretically) serve 65535 simultaneous connections per client.
Which server can process multiple request at a time?
A concurrent server handles multiple clients at the same time.
What is socket address structure?
The socket data structure defines the socket. During a socket subroutine, the system dynamically creates the socket data structure. The socket address is specified by a data structure that is defined in a header file.
What is server design?
Applications are usually designed so that one computer (or end system) acts as a server, providing a service to other computers on a network. To access a server, a program is run on a users computer, this is called a client program.
What is concurrency in Web services?
Concurrency is inherent to distributed. applications, which must process messages arriving asynchronously from. peers. In particular, high-throughput servers must process concurrent. requests from many clients.
What is a TCP segment?
A TCP segment consists of data bytes to be sent and a header that is added to the data by TCP as shown: The header of a TCP segment can range from 20-60 bytes. 40 bytes are for options.
What is a server socket?
A socket is one endpoint of a two-way communication link between two programs running on the network. A socket is bound to a port number so that the TCP layer can identify the application that data is destined to be sent to. An endpoint is a combination of an IP address and a port number.
How does a Web server handle multiple requests?
The server opens a socket that 'listens' at port 80 and 'accepts' new connections from that socket. Each new connection is represented by a new socket whose local port is also port 80, but whose remote IP:port is as per the client who connected. So they don't get mixed up.
What are the advantages of concurrent TCP connections?
You must keep multiple TCP/IP connections to the StorageGRID system open to allow idle connections to perform transactions as required. The number of client applications also affects how you handle multiple TCP/IP connections.
What is concurrency in Web services?
Concurrency is inherent to distributed. applications, which must process messages arriving asynchronously from. peers. In particular, high-throughput servers must process concurrent. requests from many clients.
Is accept blocking call?
If no pending connections are present on the queue, and the socket is not marked as non-blocking, accept() blocks the caller until a connection is present.
What is iterative server?
Concurrent Servers/Iterative server. A server that handles a simple program such as daytime server is a iterative server. But when the client request can take longer to service, the server should not be tied upto a single client.
What does "close" mean in Unix?
close () The normal Unix close () is also used to close a socket and terminate a TCP connection.
What does connect successfully return?
After connect successfully returns a TCP client that does not call bind (), getsocketname () returns the local IP address and local port number assigned to the connection by the kernel
What is concurrent server?
Concurrent Servers/Iterative server: A server that handles a simple program such as daytime server is a iterative server. But when the client request can take longer to service, the server should not be tied upto a single client. The server must be capable of handling multiple clients at the same time. The simplest way to write a concurrent server ...
What does the function doit do?
In the above program, the function doit does whatever is required to service the client. When this functions returns, we explicitly close the connected socket in the child. This is not required since the next statement calls exit, and part of process termination is closing all open descriptors by the kernal. Whether to include this explicit call to close or not is a matter of personal programming taste.
How to write concurrent server in Unix?
The simplest way to write a concurrent server under Unix is to fork a child process to handle each client. Following program shows the typical concurrent server.
