what is the difference between a web server and aplication server?

Answer 1

What is Web server

A computer that delivers Web pages to browsers and other files to applications via the HTTP protocol. It includes the hardware, operating system, Web server software, TCP/IP protocols and site content (Web pages and other files). If the Web server is used internally and not by the public, it may be called an "intranet server."

HTTP Server

"Web server" may refer to just the software and not the entire computer system. In such cases, it refers to the HTTP server (IIS, Apache, etc.) that manages requests from the browser and delivers HTML documents and files in response. It also executes server-side scripts (CGI scripts, JSPs, ASPs, etc.) that provide functions such as database searching and e-commerce.

One Computer or Thousands

A single computer system that provides all the Internet services for a department or a small company would include the HTTP server (Web pages and files), FTP server (file downloads), NNTP server (newsgroups) and SMTP server (mail service). This system with all its services could be called a Web server. In ISPs and large companies, each of these services could be in a separate computer or in multiple computers. A datacenter for a large public Web site could contain hundreds and thousands of Web servers.

Web Servers Are Built Into Everything

Web servers are not only used to deliver Web pages. Web server software is built into numerous hardware devices and functions as the control panel for displaying and editing internal settings. Any network device, such as a router, access point or print server may have an internal Web server (HTTP server), which is accessed by its IP address just like a Web site. Contrast with Web client. See application server and embedded Web server.

Web Server Fundamentals
Web browsers communicate with Web servers via the TCP/IP protocol. The browser sends HTTP requests to the server, which responds with HTML pages and possibly additional programs in the form of ActiveX controls or Java applets.

Web Server Environment
This shows all the server-side processes that can take place in a Web server and application server. There is overlap between a Web server and an application server, as both can perform similar tasks. The Web server and application server can be in the same machine or in separate computers.

A Built-in Web Server
This home page is not coming from the Web, but from the Web server built into Tally's 8106 color laser printer. Any Web browser can access the configuration panel by IP address when Web server software provides the user interface. The 192.168.1.250 is the IP address of the printer.

Web Servers Are Everywhere
Web server software is built into this EasyCom print server, which plugs into the printer's parallel port.








What is application server
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An application server is a server computer in a computer network dedicated to running certain software applications (as opposed to e.g. a file server or print server). The term also refers to the software installed on such a computer to facilitate the serving (running) of other applications.

Because the exact role of an application server depends on the architecture of the application it is serving, it is an imprecise and fluid term. Generally, however, an application server will handle most, if not all of the business logic and data access of an application which has a complementary client side. This is perceived as beneficial from a number of standpoints, chiefly the benefits of centralization.

Data and code integrity
By centralizing business logic on an individual or small number of server machines, updates and upgrades to the application for all users can be guaranteed. There is no risk of old versions of the application accessing or manipulating data in an older, incompatible manner.
Centralized configuration
Changes to the application configuration, such as a move of database server, or system settings, can be done centrally.
Security
A central point through which access to data and portions of the application itself can be managed is considered a security benefit, devolving responsibility for authentication away from the potentially insecure client layer without exposing the database layer.
Performance
By limiting the network traffic to presentation layer traffic, it is perceived that the client-server model improves the performance of large applications in heavy usage environments.
Total Cost of Ownership (TCO)
The above benefits combined are considered to represent a cost saving to a company. In practise, however, the technical challenges of writing software that conforms to that paradigm combined with the need for software distribution to distribute client code somewhat negate these benefits.

Although the term Application server applies to all platforms, it has become synonymous with the Sun Microsystems J2EE platform. It has also come to encompass servers of web-based applications, although the paradigm is more similar to mainframe based applications than traditional client-server.

History

In the later part of the 1990s, it was thought that a massive shift over to centrally served applications was likely, and that the desktop PC would be replaced by lightweight network computers. This would have been a return to the much older model of computing as it was done in the 1960s, with a large, very expensive central computer being accessed by multiple users using dumb terminals. The difference now was the widespread use of the graphical user interface (GUI). Certain products, such as Citrix's WinFrame, became quite popular, allowing standard Windows software to be run on an NT server, and accessed from a wide variety of clients, including non-Windows platforms such as Mac and Unix. So far, this shift has not happened on the predicted scale, and serving a GUI-based application over a slow network has presented a number of technical challenges that have not entirely been solved. It remains to be seen if the prediction comes true or whether the late 90s interest turns out to have been a fad.

Java application servers

Following the success of the Java platform, the term application server often refers to a J2EE application server. JBoss (Red Hat), WebSphere (IBM), Oracle Application Server 10g (Oracle Corporation), Sun Java System Application Server and WebLogic (BEA) are the better known commercial J2EE application servers. GlassFish, open source Application Server from Sun, is the first to provide robust, commercial, compatible Java EE 5 implementation.

The JOnAS application server, developed by the ObjectWeb consortium, is the first non-commercial, open source application server to have reached the official certification of compliance with J2EE. The programming language used is Java. The web modules are servlets and JavaServer Pages (JSP), and business logic is built into Enterprise JavaBeans (EJB). The Java 2 Platform, Enterprise Edition (J2EE) provides standards for containing the web components. Tomcat from Apache and JOnAS from ObjectWeb are typical of containers to put these modules into. Both organizations provide the code freely and openly (open source).

JSP is a Servlet from Java that execute in a web container--the Java equivalent of CGI scripts. JSP is a way to create HTML pages by embedding references to the server logic within the page. HTML coders and Java programmers can work side by side by referencing each other's code within their own. JavaBeans are the independent class components of the Java2 architecture from Sun Microsystems.

The application servers mentioned above mainly serve Web applications. Some application servers are targeting networks other than the Web. This is the case of SIP servers, which target telephony networks. An example of a telephony server is the [Ubiquity] SIP Application Server, which complies with the IMS architecture, as well as the SIP Servlet API standard (JSR 116).

Other platforms

The term application server has also been applied to various non-J2EE and non-Java offerings. For example, with the rising popularity of .NET, Microsoft can claim to deliver an application server. Additional open source and commercial application servers are available from other vendors. Some examples are the Base4 Server and Zope. Contrary to prior versions of this entry, Microsoft's Windows Communication Foundation is not an application server, but rather a framework for communication (middleware).

Common features

Application server products typically bundle middleware to enable applications to intercommunicate with various qualities of service — reliability, security, non-repudiation, and so on. Application servers also provide an API to programmers, so that they don't have to be concerned with the operating system or the huge array of interfaces required of a modern web-based application. Communication occurs through the web in the form of HTML and XML, as a link to various databases, and, quite often, as a link to systems and devices ranging from huge legacy applications to small information devices, such as an atomic clock or a home appliance.

Portals are a very common application server mechanism by which organizations can manage information. They provide a single point of entry for all users, they can access Web services transparently from any device, and they are highly flexible. Portals can work inside or outside of the organization, and they can attach themselves to any part of it.

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Answer 2

Web server is a public-facing server that serves web pages.

App server is usually behind the firewall and serves common apps to local users.

Answer 3

it depends on the purpose
if u configure a webserver u can also use it as an app server
webserver usually is to host web pages an appserver usually host applications used by clients