Netscape Application Server

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31 Οκτ 2013 (πριν από 3 χρόνια και 9 μήνες)

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Netscape Application Server



Application Server for Business
-
Critical Applications





Presented By : Khalid Ahmed


DS 520
-

Fall 98







OLD CLIENT
-
SERVER MODEL


Connection
Clients were required to have dedicated lines, leased lines, dialups,
or some other access to the Server.


Network Protocol
Clients had to use the same network protocols as the Server they
wanted to communicate with, TCP/IP, IPX/SPX, NetBUI, etc.


Hardware Requirements

Clients had to meet specific machine requirements: microprocessor
speed; screen resolution; RAM; hard disk space; modem speed; etc.
Clients were required to make a huge investment in hardware.



OLD CLIENT
-
SERVER MODEL



Operating System Requirements
The Clients had to run a specific Operating System and version.



Software Updates
Application updates via floppy disks or CDs were frequent. The
Client was required to perform the costly installation or update.



New Client
-
Server Model


Internet Connection

Clients need only have access to the Internet to access a website.
Network requirements are largely eliminated because TCP/IP is
the default Internet protocol.
Now it’s easy for clients to communicate with a server.


Instant Access

Clients no longer need to install or update applications, they
simply access the service on a website. Any updates you’ve made
to the application will be immediately available.

Now it’s easy and inexpensive for you to update your services.


Client Browser
Clients can use almost any browser and they don’t need special
hardware. They can also use any Operating System and version
for which a web browser exists.
Now it’s inexpensive for clients to access a server.

DB

Databases

Documents

Enterprise

Data

Web

Server

CGI, SSJS, NSAPI,

ISAPI, WAI, Etc.

Client

Browser

Internet Connection


Basic Web Applications


Robust Web Applications

Presentation

Tier

Rich Clients


(
Java C/C++, VB
)

Web

Browser


Business Logic
Tier

Web

Servers

Application
Servers

Data Tier

Databases

Enterprise C/S
Applications

Legacy

Systems

Documents

HTTP


Requirements of Web
-
based Business


Applications


Transaction

Management

Capabilities


Scalability


High Performance


Robustness


Security


In order to deploy robust applications over the web, the web
solution must deliver on the following key requirements for
business critical computing:


Shortcomings of the Web for Deploying


Business Applications


Lack of transaction management capabilities and
stateless environment.


No model for application scalability.


Unpredictable performance under heavy and varying
loads.


Difficult application deployment and management.


Lack of end
-
to
-
end security.




Netscape Application Server (
NAS
)


Rapid deployment of transactional applications.


Session and state management.


High scalability.


High performance.


Security.


Dynamic content generation.


Management capabilities.

Netscape application server is a programmable application server. It
provides all the core system and application services required to
enable rapid deployment and facilitate management of high volume,
transaction
-
based web applications.

Some of it’s key features include:


Key Components of Netscape Application


Server


Netscape Application Server Architecture


Netscape Application Server Components


Web Server to Netscape Application Server (NAS)
Communication

Communication between a web server and NAS occurs
through NSAPI, ISAPI and optimized CGI.
Communication with the web browsers occurs through
the HTTP, SHTTP or SSL protocols.


Load Balancing System
Incoming requests first pass through the NAS load
balancing system, which directs requests to available
servers for optimized processing under heavy loads.


Request Management System
The NAS is a multi
-
threaded system and the Request
Management System assigns threads from a dynamic
thread pool to process the requests.


Netscape Application Server Components


Application Logic Processing System
The application
logic processing system handles all requests related to
processing business logic. Requests are identified by
their Globally Unique IDentifier (GUID) and checked
against the Global Directory Service (GDS). The GDS
determines the language of the application logic object.
It then loads the appropriate language specific handler
for the request.It could be a .class file for a java
application or a .DLL file for a C++ application.


System and Application Services
These services can be broadly classified into four
categories:


Netscape Application Server Components


Administrative Services

The administrative services provides us with a
framework for managing distributed NAS and
applications.

It supports Java based administrator
tools for easy point
-
and
-
click management of servers
and applications.


Kernel Services

It provides low
-
level services to all the other services
and sub
-
systems.



Transaction Management System



Database Access Services



Presentation Services



Application Services


How does the NAS operate ?

When a request comes in from a web browser, the
request is passed to the web server via the HTTP,
SHTTP or SSL protocol. The request is processed
by the appropriate Web Connector such as NSAPI
(for Netscape webservers) or ISAPI (for Microsoft
web servers). The request is then forwarded to a
correspondong Listener. The web connectors and
listeners manage the passing of requests from the
web server to the NAS.

In a environment with multiple NAS, a request is
first handled by the Load Balancing System. It
then directs the request to the server best suited
for this process. The Request management system


How does the NAS operate ?

then assigns threads from a dynamic thread pool to

process the request.

The request is then handed to the application logic

processing system where the appropriate application
logic is executed to process the request. Application
logic processing might involve calling one or more
functions from the following subsystems:



Data Access Services such as database access


operations and connection caching.



Transaction management system such as transaction


manager and database request manager.



System and Application Services such as session


manager and distributed state manager.



Presentation Services such as presenting formatted


data to the browser.


NAS Applications as part of a


three
-
tiered environment.

The applications on a Netscape Application Server run


in a distributed, three
-
tiered environment.


NAS Applications as part of a


three
-
tiered environment.

Client Tier

The first tier is the client or user interface tier. The
software providing the user interface can be either a
web browser displaying a HTML page or a client
application installed on desktop PC’s.

Middle Tier

The middle tier is the NAS. This tire consists of server
machines running both NAS software and server
-
side
application code.

Database Tier

The database tier consists of one or more database
servers, which can be from different vendors.


Netscape Application Builder



Rapid Development of Business Applications



Wizards for Point
-
&
-
click Development



Pre
-
built Application Services and Class Libraries (Java, C/C++)



Reusable Application Components



Distributed Deployment of Application Components



Distributed Development Using Three
-
Tier Programming Model


Netscape Application Builder


Robust Application Development Tools



Application Logic


Designer



HTML Designer



Query Designer



Project Manager



Third
-
party Tool


Support


Netscape Server administration


Advanced cluster management


Enterprise
-
wide views of all servers and processes


Event monitoring & alerts


Multi
-
view graphical

performance monitoring


ACL, User & Group

Management


Load balancing

customization


Application administration


Application partitioning


Integrated deployment


Summary

Key Benefits of the Netscape Application Server:



Enables Rapid Development of Business Applications



Provides Industry Leading Performance & Scalability



Provides High Availability & Reliability



Enables Enterprise Application Integration



Allows Client
-
Independence

(HTML, Java, C++, VB)



Provides Open & Extensible Architecture