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An application server is a server that is designed for or dedicated to running specific applications. Sometimes referred to as a type of middleware, application servers occupy a large chunk of computing territory between database servers and the end user, and they often connect the two. An application server is used to run certain kinds of applications. Another kind of application server is one that runs an operating system. This is more old-fashioned, but it is still used. Certain computers, more commonly called terminals, connect to an application server in order to access basic functions. In the network of the hospital, the user interface, which runs on the user's computer, the middle tier runs on a server and is often called the application server processes data and the database server the data required by the middle tier.
File Transfer Protocol (FTP) is a standard network protocol used to exchange and manipulate files over a TCP/IP based network, such as the Internet. FTP is built on a client-server architecture and utilizes separate control and data connections between the client and server applications. Client applications were originally interactive command-line tools with a standardized command syntax, but graphical user interfaces have been developed for all desktop operating systems in use today. FTP is also often used as an application component to automatically transfer files for program internal functions. FTP can be used with user-based password authentication or with anonymous user access. The Trivial File Transfer Protocol (TFTP) is a similar, but simplified, not interoperable, and unauthenticated version of FTP. The objectives of FTP, as outlined by its RFC, are:
To promote sharing of files (computer programs and/or data).
To encourage indirect or implicit use of remote computers.
To shield a user from variations in file storage systems among different hosts.
To transfer data reliably, and efficiently.
A database server is a computer program that provides database services to other computer programs or computers, as defined by the client-server model. The term may also refer to a computer dedicated to running such a program. Database management systems frequently provide database server functionality, and some DBMSs (e.g., MySQL) rely exclusively on the client-server model for database access. In the network of the hospital, the database provides the data which has been stored in the database server and is required to the clients.
A Backup Server is an excellent way for you to save your important files into one single compressed file. If the staff of the hospital seem to be using the computers more and more often to store pictures, work on important files, and exchange emails, itââ‚¬â„¢s important that they make regular back ups of their files, incase their computer crashes when they least expect it. The best part of Backup Server is itââ‚¬â„¢s affordable and they can transfer the compressed file onto another computer or hard drive. If they are computer savvy, they can even upload the backup file using a built-in ftp function to your own server for safe and convenient offsite storage, as part of your regular back up.
In computer networks of a hospital, a proxy server sit between a client program (typically a Web browser) and an external server (typically another server on the Web) to filter requests, improve performance, and share connections. A client connects to the proxy server, requesting some service, such as a file, connection, web page, or other resource, available from a different server. The proxy server evaluates the request according to its filtering rules. A proxy server may optionally alter the client's request or the server's response, and sometimes it may serve the request without contacting the specified server. In this case, it 'caches' responses from the remote server, and returns subsequent requests for the same content directly. A proxy server has four purposes:
To keep machines behind it anonymous (mainly for security).
To speed up access to a resource (via caching). It is commonly used to cache web pages from a web server.
To censor network services or content.
To forge transmitted content before delivery, e.g. to insert advertisements.
A proxy server that passes requests and replies unmodified is usually called a gateway or sometimes tunneling proxy. A proxy server can be placed in the user's local computer or at various points between the user and the destination servers or the Internet.
Dynamic Host Configuration Protocol (DHCP) is a network protocol that enables a server to automatically assign an IP address to a computer from a defined range of numbers (i.e., a scope) configured for a given network. DHCP assigns an IP address when a system is started, for example:
A user turns on a computer with a DHCP client.
The client computer sends a broadcast request (called a DISCOVER or DHCPDISCOVER), looking for a DHCP server to answer.
The router directs the DISCOVER packet to the correct DHCP server.
The server receives the DISCOVER packet. Based on availability and usage policies set on the server, the server determines an appropriate address (if any) to give to the client. The server then temporarily reserves that address for the client and sends back to the client an OFFER (or DHCPOFFER) packet, with that address information. The server also configures the client's DNS servers, WINS servers, NTP servers, and sometimes other services as well.
The client sends a REQUEST (or DHCPREQUEST) packet, letting the server know that it intends to use the address.
The server sends an ACK (or DHCPACK) packet, confirming that the client has been given a lease on the address for a server-specified period of time.
When a computer uses a static IP address, it means that the computer is manually configured to use a specific IP address. One problem with static assignment, which can result from user error or inattention to detail, occurs when two computers are configured with the same IP address. This creates a conflict that results in loss of service. Using DHCP to dynamically assign IP addresses minimizes these conflicts.
The Domain Name System (DNS) is a hierarchical naming system for computers, services, or any resource connected to the Internet or a private network. It associates various information with domain names assigned to each of the participants. Most importantly, it translates domain names meaningful to humans into the numerical (binary) identifiers associated with networking equipment for the purpose of locating and addressing these devices worldwide. An often used analogy to explain the Domain Name System is that it serves as the "phone book" for the Internet by translating human-friendly computer hostnames into IP addresses. For example, www.example.com translates to 18.104.22.168. Internet domain names are easier to remember than IP addresses such as 22.214.171.124 (IPv4) or 2001:db8:1f70::999:de8:7648:6e8 (IPv6). The Domain Name System distributes the responsibility of assigning domain names and mapping those names to IP addresses by designating authoritative name servers for each domain. Authoritative name servers are assigned to be responsible for their particular domains, and in turn can assign other authoritative name servers for their sub-domains. In general, the Domain Name System also stores other types of information, such as the list of mail servers that accept email for a given Internet domain.
Windows Internet Name Service (WINS) servers dynamically map IP addresses to computer names (NetBIOS names). This allows users to access resources by computer name instead of by IP address. If you want this computer to keep track of the names and IP addresses of other computers in your network, configure this computer as a WINS server. WINS provides the following benefits over other NetBIOS name resolution methods:
WINS name resolution reduces NetBIOS name query broadcast traffic because clients can query a WINS server directly instead of broadcasting queries.
WINS enables the Computer Browser service to collect and distribute browse lists across IP routers.
The WINS dynamic name-to-address database supports NetBIOS name registration and resolution in environments where DHCP-enabled clients are configured for dynamic TCP/IP address allocation.
The WINS database also supports centralized management and replicates name-to-address mappings to other WINS servers.
WINS and DNS can be used in the same environment to provide combined name searches in both namespaces.
A Web server serves static content to a Web browser by loading a file from a disk and serving it across the network to a user's Web browser. This entire exchange is mediated by the browser and server talking to each other using HTTP. For example, if the staffs of the hospial enter the URL http://www.pcwebopedia.com/index.html in your browser, this sends a request to the server whose domain name is pcwebopedia.com. The server then fetches the page named index.html and sends it to their browser. This is important for the staffs of the hospital to look for the imformation as they need it in their job.