servers names
TRANSCRIPT
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JAVA SERVLETSJAVA SERVLETS
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Web ServerA web server is a network server that
manages access to files, folders and other resources over Internet or local Intranet via HTTP ◦ Handle permissions◦ Execute programs◦ Keep track of directories and files◦ Communicate with client computers
A web server consists of a computer with:◦ a suitable operating system◦ a suitable file system◦ a network connection◦ web server software – which accepts requests
from browsers such as IE and Netscape
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Web Server ………A Web server handles the HTTP protocol.
When the Web server receives an HTTP request, it responds with an HTTP response, such as sending back an HTML page.
To process a request, a Web server may respond with a HTML page or image, send a redirect, or delegate the dynamic response generation to some other program such as CGI scripts, JSPs (JavaServer Pages), servlets, ASPs (Active Server Pages), server-side JavaScripts, or some other server-side technology.
such server-side programs generate a response, most often in HTML, for viewing in a Web browser.
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Web Server ……..Web server's delegation model is fairly simple.
When a request comes into the Web server, the Web server simply passes the request to the program best able to handle it.
The Web server doesn't provide any functionality beyond simply providing an environment in which the server-side program can execute and pass back the generated responses.
The server-side program usually provides for itself such functions as transaction processing, database connectivity, and messaging.
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Web Server …….
While a Web server may not itself support transactions or database connection pooling, it may employ various strategies for fault tolerance and scalability such as load balancing, caching, and clustering—features oftentimes erroneously assigned as features reserved only for application servers
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Web ArchitectureMulti-tier architecture:
◦ Application-level or middleware: has an application server, which is used to find requested data and services, makes them available for viewing, and carries out transactions.
◦ Data and service level: has a variety of data and services accessible by the application server.
Databaseserver
Client computers with web browsers
Web server
Internet
HTTP request
HTTP response
Presentation level
Content level Data and service level
Application server
Application level
Billing system
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Application Server Application server exposes business
logic to client applications through various protocols, including HTTP.
Application server provides access to business logic for use by client application programs. The application program can use this logic just as it would call a method on an object (or a function in the procedural world).
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Application ServerApplication server clients can include
GUIs (running on a PC, a Web server, or even other application servers.
The information traveling back and forth between an application server and its client is not restricted to simple display markup.
Instead, the information is program logic. Since the logic takes the form of data and method calls and not static HTML, the client can employ the exposed business logic however it wants.
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Application Server In most cases, the server exposes this
business logic through a component API, such as the EJB (Enterprise JavaBean) component model found on J2EE (Java 2 Enterprise Edition) application servers.
Moreover, the application server manages its own resources that include security, transaction processing, resource pooling, and messaging.
Like a Web server, an application server may also employ various scalability and fault-tolerance techniques.
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Application Server
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Web servers Web servers
Internet Information Server
Personal Web Server
Java Web Server
Apache Tomcat Server
Web Logic
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Tomcat web serverTomcat web serverFor the deployment the steps are to be
followed:
1. Put the source code for the servlet in the Server_root/webapps/ROOT/WEB-INF/classes
directoryThis is a standard location for servlet class files.2. Include server_root /lib/servlet.jar somewhere
in class path so that the two packages will be included in the class path.
3. Compile the servlet using javac filename.java4. After compiling start the server by looking the
startup.sh script in the server root/bin directory
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To access the servlet, type the URL in the browser as (if the server is on the local machine)
http://localhost :8080/servlet/passwordcheck.
Tomcat web serverTomcat web server
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Introduction to servletsIntroduction to servletsServlet runs on the server and will
respond to a request from the client either in the form of HTML pages, dynamic pages or indeed applets.