CHAPTER 8 ?– USING THE ASP.NET AJAX CONTROL TOOLKIT (PART 2) 180
Figure 8-8. NoBot control used invisibly in a login page
The NoBot extender can also limit the number of requests per IP address as well as a
delay between the request and postbacks. These are all attributes of a human user
accessing the web application through a browser. Table 8-8 lists the main properties of
the NoBot control.
Table 8-8. NoBot Control Properties
Property Name Description
CutoffMaximumInstances Maximum number of postbacks allowed by a single IP
address within the allowed timeframe
CutoffWindowSeconds Cutoff window (in seconds) for previous postbacks from an
IP address
OnGenerateChallengeAndResponse An event used to implement custom challenge/response
logic
ResponseMinimumDelaySeconds Minimum number of seconds required for a postback
To use the NoBot extender in your page, you can start with a couple of TextBox controls
for user input signifying a typical form and an instance of the NoBot extender.
In the following code segment, a method name is assigned to the
OnGenerateChallengeAndResponse property.
Pages:
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263