Page 123 - DCAP603_DATAWARE_HOUSING_AND_DATAMINING

Unit 6: Source Integration

Today’s web servers pull double duty. Not only do they serve up file content to hordes of web notes
clients, but they perform rudimentary application processing, as well. With enabling technologies
such as Common Gateway Interface (CGI), Netscape Application Programming Interface
(NSAPI), and Internet Server Application Programming Interface (ISAPI), web servers can query
the web client for information, and then, using web server APIs, they can pass that information
to an external process that runs on the web server (Figure 6.6). In many cases, this means users
can access information on a database server or on application servers.
figure 6.6: using the Web server api to customize information sent to the client Level

Database servers

Database servers, when leveraged with portals work just as they do in more traditional client/
server architectures they respond to requests and return information. Sometimes the requests
come from web servers that communicate with the database server through a process existing on
the web server. Sometimes they come directly from web client communication with the database
server via a Call-Level Interface (CLI), such as JDBC for ActiveX.

Back-end applications

Back-end applications are enterprise applications existing either within a single enterprise or
across many enterprises. These are typically a mix of ERP systems, such as SAP R/3 or PeopleSoft,
custom applications existing on mainframes, and newer client/server systems. Portals gather the
appropriate information from these back-end systems and externalize this information through
the user interface.
Although the mechanism employed to gather back-end information varies from technology to
technology, typically, portal development environments provide connectors or adaptors to link
to various back-end systems, or they provide APIs to allow developers to bind the back-end
systems to the portal technology.
application servers

Application servers work with portal applications by providing a middle layer between the back-
end applications, databases, and the web server. Application servers communicate with both the
web server and the resource server using transaction-oriented application development. As with
three-tier client/servers, application servers bring load-balancing recovery services and fail-over
capabilities to the portal.

LoveLy professionaL university 117