8.9 Simple Distributed Web Services Using CORBA

The addresses for Implementation Repositories and naming services can be imbedded within HTML and used as part of a CGI call to a Web server. This technique can be used to implement simple distributed Web services using CORBA. Example 8.6 shows a simple HTML entry. When the link is clicked, a CORBA client executes. The CORBA client can then get to the server using the address of the Implementation Repository and the naming service that was passed from the HTML CGI command.

Example 8.6 A HTML document with an embedded call to a CORBA client program.
 <HTML> <HEAD> <TITLE> CORBA</TITLE> </HEAD> <BODY> <a href="http://www.somewhere.org/cgi-bin/client?- ORBImplRepoAddr+inet:hostname:port+- ORBNamingAddr+inet:hostname:port">Click</a> <P> </HTML> 

Here the client refers to a program that will access a CORBA producer or server program. The client has the name of the object that needs to be accessed and uses the naming service to resolve the reference. This technique does not require code to be downloaded to the user 's computer. Instead, the client code is executed on the Web server and will access the CORBA-based server program whether it is on an intranet connected to a Web server or somewhere else on the Internet. The client program will respond to the HTML browser using the appropriate CGI protocol. Figure 8-10 shows a simple Web services configuration using CORBA components .

Figure 8-10. A simple Web services configuration using CORBA components.

graphics/08fig10.gif

In addition to http , telnet can be used to launch CORBA-based clients and servers. The http protocol and the telnet protocol can be used to support global distribution of CORBA components. It is important to remember software, data, and system security when considering the design of distributed components that will be used across the Internet or intranet. Although security implementations and requirements are beyond the scope of this book, we mention it as a fundamental consideration in any distributed design. The Implementation Repository can be used to store security-type information. A CORBA implementation can be used in conjunction with SSL (Secure Socket Layer) and SSH (Secure Shell).



Parallel and Distributed Programming Using C++
Parallel and Distributed Programming Using C++
ISBN: 0131013769
EAN: 2147483647
Year: 2002
Pages: 133

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