Download ActiveX

Active X
Microsoft’s Answer
to
Dynamic Content
Reference:
Using Active X by Brian Farrar
QUE pub. @96
Static Content
1
Client
www
1
Server
Internet
2
2
1- Browser asks for a page
2- Server returns page and Browser displays
CGIs
1
Client
www
1
Server
Internet
3
3
2
1- Browser invokes CGI program
2
CGI
program
2- Server runs CGI program to create page
3- Server returns result of CGI to browser to display
Does CGI make page dynamic?
Yes
No
• result of whatever CGI • page itself doesn’t do
produced
anything
• created on the fly
• browser renders it and
is finished
• looks like any other
page
More Dynamic Activity
Needed at Client
• Helper apps launched by browser as
external program based on MIME type of
file.
• Examples
– Adobe acrobat files
– Quicktime video
– RealTime audio
Helper App Problems
• User needs to know what to download
–
–
–
–
–
not as much of a problem now: automatic
more software to install on client
author must figure out how to distribute code
version control maintenance problems
still widely used in past
Versions of HTML
•
•
•
•
HTML 1.0
CGIs and HTML 2.0
HTML 3.0
….
STILL NO
DYNAMIC
CONTENT
MANAGED
BY THE
CLIENT
Other Ways to Make Dynamic
Client Pull
• after a delay client
asks for another page
to display
• uses <META> tag
Server Push
• Basically a cgi
– Sends a file
– delays
– sends another file
Forms and CGIs
• Forms uses standard input controls to get
user input
• Browser invokes the CGI indicated on the
page with data from the from
• Server can respond to users differently!
• Use GET or POST methods
SUN adds dynamic content
•
•
•
•
Java applets
Java
Java Script
Hot Java Browser (not a hot item)
Java
• A language designed by SUN to be
executed by an interpreter INSIDE THE
BROWSER!
• Client downloads a program and executes it
rather than displaying a page
• Any browser which adopts java can run the
program - multi-platform!
• All major browsers quickly adopted it.
What else does Java add?
• Authors distribute programs over web
• User clicks and gets latest program rather
than a static page
• Always the latest version
• Browser can be user interface for all
programs
• Authors control distribution / authenticate
Applets vs Applications
Java Applets
• java programs which
run in the browser
• security concerns
addressed in browser
by crippling access to
disk etc.
Java Applications
• like applets
• run OUTSIDE the
browser
• standalone programs
• compilable
• like c++ applications
• security not an issue
Java Script
• Whole new beast
• Much less powerful
• Allows for
– user controls on form
– handlers for events
• Dynamically and Locally control browser
• LOGIC in html
• Procedures actually at top of html source
VB Script
• A Microsoft thing
• Same concept as Java Script
• Only in Internet Explorer (3.0 +)
NETSCAPE
JavaScript
Internet Explorer
VBScript
Another approach
• Not as general as a new language
• Easier to display MIME types
• Netscape has an API to let program actually
be absorbed into the browser
• Called PLUG-INS
A look back!
Programming Development
• OOP/OOD
• RAD Tools (graphical)
• interprogram/process communication
Interprocess/program
Communication
• Unix
– sockets
– pipes
• Microsoft adds
– DDE
– Drag n Drop OLE
• embedded or linked
• Manual
– export and import
Objects and Design
Object Communication
• Objects interact by invoking methods and
passing messages to handlers
• Would like to have objects ask
– what another object can do
– what methods are available
and then use the functionality available
Similarities apps and html scripts
• Message/event
handlers
• window controls
but apps
can be OO
design extensibility
• Message/event
handlers
• window controls
Microsoft View
OLE
Application
Application & OLE object
have strict boundaries
ActiveX
Application
Application & ActiveX object
have loose boundaries
Microsoft View
ActiveX
Browser
ActiveX
Application
Same Active X objects used in Browser AND application
Application program/design effort more usable