IP address: contains sufficient information to uniquely identify a network and a specific computer on the network.
IP address contains Class ID, Net ID and Host ID
For example, nova.ksi.edu has IP address 192.217.188.1
11000000.11011001.1011110.00000001 ^^^----- -------- ------- ******** First 3 bits 110 indicates Class C Next 21 bits is Net ID Last 8 bits is Host ID
HTML CONCEPTS
Hyptertext: Test with links to other textsHome Page: The root of a hypertext structure
Web Browser: A tool to retrieve a document using URL from the Web server, interpret its HTML and present it to the user
URL: Universal Resource Locator, the "address" of a Web page
HTML: Hypertext Markup Language is the language to design the Web page
Tag: HTML essentially is made up out of tags, which are strings enclosed in angular brackets.
< HTML> < HEAD> < TITLE>Sample HTML document< /TITLE> < /HEAD> < BODY> < H3>Sample HTML document< /H3> < A HREF="http://www.ksi.edu/"> KSI Graduate School of Computer Science< /A> < FORM METHOD="get" ACTION="http://www.webbase.com/docs/webbase/examples/getname.htf"> Please enter the name to search for: < INPUT NAME="name" SIZE=15 VALUE="Denny"> < INPUT TYPE=SUBMIT value="Enter">< /FORM> < /BODY> < /HTML>The above HTML form as seen by the user looks like this:
Sample HTML document
KSI Graduate School of Computer ScienceIf you click the ENTER button, this will send a "GET" request to the server that looks like:
-
http://www.WebBase.com/docs/webbase/examples/getname.htf?name=Denny
This form 'getname.htf' takes the Query_String as input and returns another form which is then presented to the user.
This technique of passing information to the server is used by the common gateway interface CGI to perform tasks using CGI scripts (programs). It is also used by WebBase to pass information to the WebBase form (htf) to perform database retrieval/update operations.
For more information, consult A Beginner's Guide to HTML (1995)
COMPARISON OF DATABASE AND HYPERBASE
Hyperbase supports:* Non-linear text
* Information expansion
* Information navigation
The Difference between Database and Hyperbase:
HYPERBASE DATABASE
--------- --------
arbitory link predefined index
irregularity regularity (all the record
has same attributes)
good for navigation good for data processing &
& exploration information processing
easy to handle more difficult to handle
exceptions exceptions
User may get lost User must formulate queries
in hyperspace to retrieve information and
(disorientation) may not find what he does not
know
A GRAPH-THEORETIC MODEL FOR HYPERBASE
A hyperbase Hg is an ordered triple (N,A,L) whereN = {N1,...,Nm} is a set of information nodes
A = {Al1,...,Amn} is a set of anchors, or subregions within nodes, such that each node Ni has one or more anchors {Ai1, ..., Ain}
L = < Aij, Akl> is a set of links or ordered pair of anchors.
Browsing Operator:
A function mapping a link's first anchor (link originator) to a link's second anchor (link end0Authoring Operator:
defines a link by identifying its two anchors.LOST IN HYPERSPACE
A hyperbase becomes very complex because it has many nodes and linksTo solve the problem, we can try to cluster the nodes and/or links to form more abstract structures
Aggregate: A set of distinct concepts that taken together form a more abstract concept.
Aggregate Clustering with Exceptions ACE:
From the input hypertext graph, construct an aggregated E-R diagram (regularity) and an exception graph (irregularity)
Reference:
Y. Hara, A. M. Keller, G. Wiederhold, "Implementing Hypertext Database Relationships through Aggregations and Exceptions", Proc. of 3rd ACM Conference on Hypertext, San Antonio, Texas, Dec 15-18, 1991, 75-90.