Prentice Hall and Sun Microsystems. Personal use only; do not redistribute.

1.2 The Advantages of Servlets Over  Traditional  CGI

7

example, servlets could be embedded in mail or FTP servers to extend their

functionality. In practice, however, this use of servlets has not caught on, and

I'll only be discussing HTTP servlets.

1.2 The Advantages of Servlets 

Over  Traditional  CGI

Java servlets are more efficient, easier to use, more powerful, more portable,

safer, and cheaper than traditional CGI and many alternative CGI like tech 

nologies. 

Efficient

With traditional CGI, a new process is started for each HTTP request. If the

CGI program itself is relatively short, the overhead of starting the process can

dominate the execution time. With servlets, the Java Virtual Machine stays

running and handles each request using a lightweight Java thread, not a

heavyweight operating system process. Similarly, in traditional CGI, if there

are N simultaneous requests to the same CGI program, the code for the CGI

program is loaded into memory N times. With servlets, however, there would

be N threads but only a single copy of the servlet class. Finally, when a CGI

program finishes handling a request, the program terminates. This makes it

difficult to cache computations, keep database connections open, and per 

form other optimizations that rely on persistent data. Servlets, however,

remain in memory even after they complete a response, so it is straightfor 

ward to store arbitrarily complex data between requests.

Convenient

Servlets have an extensive infrastructure for automatically parsing and decod 

ing HTML form data, reading and setting HTTP headers, handling cookies,

tracking sessions, and many other such high level utilities. Besides, you already

know the Java programming language. Why learn Perl too? You're already con 

vinced that Java technology makes for more reliable and reusable code than

does C++. Why go back to C++ for server side programming? 

Second edition of this book: www.coreservlets.com; Sequel: www.moreservlets.com.

Servlet and JSP training courses by book's author: courses.coreservlets.com.