Use true Ajax from scratch
Make
Script based web service which could be called by JavaScript
I
remember the days when I need to call web service from JavaScript using some
HTML component called webservice.htc. It was a pain to consume web service
using that component as compare to current solution provided by Asp.net Ajax
team of Microsoft. I must say, Hats off to Microsoft for making life easier of
the developers of their technologies. Following are few factors for using
“calling web service from JavaScript”.
When
you need to:
- Call web
server and perform some operation on server like updating database or some
File I/O operations or have to queue the requests and have less to do on
client side like just need to show Operation completed or data based
updated.
- Send request
to web server asynchronously and don’t want to put user on wait for
completion of request
- Perform
operation on server side more efficiently as you wont follow page life
cycle
When
you don’t need to:
- Initiate Page
object and/or need to follow page life cycle
- Post back page
and Render page automatically
- Send request
to web server synchronously and put user on wait of completion of
processing
- Submit form
- Use cache,
session or need to access any asp.net intrinsic object
Aforementioned
points tells simply, when to call web service from JavaScript and when not.
For more details and better understanding please visit following link http://worldofasp.net/tut/ajax_webservice/Ajax_enabled_web_service_237.aspx
Thanks
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XMLHTTPRequest
Normally,
when you have to do some operation at server side, say some database oriented
operation like any of well known CRUD (create, retrieve, update and delete)
operations. You will submit whole form/page to server and get a whole new page
from server to re paint on your browser. In very few, situations that are ok
but mostly its not required at all.
Suppose,
you have header image, left navigation bar, footer links like (contact us,
about us, privacy policy…) and in middle of page some textboxes and one submit
button.
You
fill those textboxes and want to save given information in database and then
clear the textboxes. Sounds good!
But
what happen, when you click on submit button, all the contents on the web page
will go to the server like header, footer, navigation bar and your textboxes.
Purpose of submit button was to save information given in database then why
header, navigation bar and footer being sending to server. I guess, it doesn’t
make sense until they are needed to update.
So,
if you want to send your specific controls data only to server and want to
update those controls at browser side, then here comes “XMLHTTPRequest” object.
XMLHTTPRequest
is JavaScript object which used to send request to server and receive response
from server. Through XMLHTTPRequest, you can communicate with server
synchronously and asynchronously as well. It depends upon your need of
communication. If your next step(s) relying on server response then you need
synchronous communication pattern but if don’t want to keep user on wait, don’t
want to freeze User Interface (UI) at user side and can proceed without having
result on next line of call then you can use asynchronous communication pattern.
For more details and better understanding please visit following link http://worldofasp.net/tut/XMLHTTPRequest/XMLHTTPRequest_236.aspx
Thanks
Kindly feedback :)