我的ASP.NET页如何在客户端代码和服务器代码之间来回切换几次？

Question

OK, the tite seems a little confusing, so I'll try to explain more thoroughly...

The process the page does currently follows the following sequence: - User clicks a button - server-side code goes retrieve data from the DB and exposes said data to the client using, populating, let's say, hidden fields. - client-side code uses this data to fire up a an ActiveX component which performs a few tasks with the data provided.

And this works fine, however, we need to optimize the process because the ActiveX component is not fit to handle high volumes of data. We need to send data into "blocks" to the component, rather them send all data at once as it is done today.

However, I just hit a roadblock here, on how can I make the page go back and forth from server to client code multiple times? Like... "user clicks a button, server retrieves first block of data, sends to client, client executes ActiveX for the first block, client requests next block, server retrieves second block, sends to client, client executes ActiveX for the second block, client requests third block... and so on"? I can't get past the first request, since I can't register a client script block 2 times and expect AJAX to handle those multiple sequential callbacks...

Or is there a way?

Answer 1

This sounds more like an architectural issue than anything else.

What you should be doing here is:

1) User clicks a button. This is NOT a regular submit button. Just a plain old button that executes some local javascript.

2) Local javascript makes an AJAX request to determine how many records are available.

3) That javascript then does a loop based on the number of available records divided by the amount you want to pull per chunk.

3.a) Execute AJAX request for a chunk

3.b) Throw the data into your ActiveX control - which, btw, I really would suggest you guys think about getting rid of. There are so many issues with ActiveX that it's not even funny.

4) Repeat 3.a and 3.b until completion.

You'll notice that at no point was a full post back performed. You'll also notice that you shouldn't have to register any client script blocks.

Now the draw back here is purely in the ActiveX control. Can it be instantiated from javascript multiple times in a page or are you forced to only use a single instance?

If it's limited to a single instance, then you'll need a different approach entirely.