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NETSCAPE APPLICATION SERVER

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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.
     Basic Web Applications


                                                  Documents




                                             DB
      Internet Connection
                                      Databases



 Client                  Web                  Enterprise
Browser                 Server                  Data
                        CGI, SSJS, NSAPI,
                        ISAPI, WAI, Etc.
                          Robust Web Applications


Presentation                       Business Logic        Data Tier
    Tier                                Tier

             HTTP
                              Documents

                                                         Databases

    Web              Web
  Browser           Servers


                                                        Enterprise C/S
                                                         Applications


                                          Application
                                            Servers


Rich Clients                                               Legacy
(Java C/C++, VB)                                          Systems
    Requirements of Web-based Business
    Applications


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

 Transaction Management Capabilities
   Scalability
   High Performance
   Robustness
   Security
 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)


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:

   Rapid deployment of transactional applications.
   Session and state management.
   High scalability.
   High performance.
   Security.
   Dynamic content generation.
   Management capabilities.
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


        Transaction Management System
        Database Access Services
        Presentation Services
        Application Services

 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.
       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

				
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posted:9/10/2011
language:English
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