Where Application Servers Fit in 3-tier Architecture
Features of the Application Servers
1.Component Management : - Provides the manager for
handling all the components and run time
services like session management, synchronous/asynchronous
client notifications and executes server business logic.
2.Fault Tolerance: - Ability of the Application server
with no single point of failure, defining policies for recovery
and fail-over recovery in case of failure of one object or group
of objects.
3.Load Balancing: - Ability to send the request to the to
different servers depending upon the load and availability
of the server.
4.Transaction Management
5.Management Console :- Single point graphical management
console for remotely monitoring clients and server clusters
6.Security: Security features for applications security
Types of Application Servers
(Source: Upstream Consulting Document)
Application servers are categorised mainly in 3 types:
Web Information Servers: This type of server employs HTML
templates and scripts to generate pages incorporating values
from the database in them. These types of servers are stateless
servers. Some of these types of servers are Netscape Server,
HAHT, Allaire, Sybase, SilverStream etc.
Component Servers: The main purpose of these servers are to
provide database access and transaction processing services to
software components inlcuding DLL's, CORBA, and Java Bean.
Firstly, they provide environment for server-side components.
Secondly, they provide access to database and other services to
the component. These types of servers are stateless servers for
instance:
MTS - provides interface for DLL.
and other servers lying in this category are
Sybase Jaguar, IBM Component broker.
Active Application Server: This type of server supports
and providesA rich environment for server-side logic expressed
as objects, rules and components. These types of servers are
stateful servers and best suitable for dealing with based
eCommerce and decision processing.
Stateful servers are those servers which play the role of
transaction co-ordinator and manage the data state, while
Stateless servers doesn't do these things completely on their
own, but have to rely on database or transaction monitors
for the completion of the transaction.
NEXT ->
