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(a) Explain the terms HotJava and Java
Applet. [2]
- HotJava: Is a web browser written in Java
(1 mark)
- Java Applet: Java code (usually for graphical effects) which is
interpreted within a web browser (1 mark)
(b) What is Java bytecode? Describe
how bytecode is executed on the host system. [4]
- Is a Java compiled code (1 mark), that
is architecturally neutral or
platform independent code (1 mark)
- Java bytecode is interpreted by emulating virtual machine (1 mark),
the semantics of this machine are given by the Java Virtual Machine
(JVM) specification (1 mark)
Give credit for valid alternative answers.
(c) Show the <A> tag that is needed
to make the string “ICS” be a hyperlink to http://www.informatics.edu.sg.
[2]
<A HREF=“http://www.informatics.edu.sg”>
ICS </A>
(1 mark for showing <A HREF, plus 1 mark for being correct in every
detail.)
(d) Identify and explain any two ways
of improving the performance of the web browser on a client system.
[4]
- Web Caching (1 mark): to minimise the number
of TCP connections,
often web pages are stored at the browser in case they are needed
again (1 mark)
- Pipelining (1 mark): overlapping requests and parallel retrieval
from
client system (1 mark)
Give credit for valid alternative answers.
(e) Some web browsers attempt to speed
up browsing by automatically fetching all the pages that can be reached
via hyperlinks from the page your are reading, and then all the pages
linked from those pages, and so on. What benefits and problems can
you see with this scheme? [3]
Likely benefits:
Fast browsing; when you click the page will already have been cached
(1 mark)
Problems:
High network usage; many pages are fetched unnecessarily; may be
antisocial (1 mark)
There may be circular references; the process could go on forever
(1 mark)
You could end up cluttering your hard disk with substantial parts
of the
Web (1 mark)
Award marks for these or other valid points. This question is slightly
open-ended; it tests whether the candidate can apply his or her
knowledge of web browsing and cacheing.
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