DB caching the html rendered by a .aspx page

J

Jon Maz

Hi,

My goal is to take the entire html/javascript stream spat out by .aspx pages
and save them as simple strings in a database (for caching purposes).

I'm not sure how I can get hold of this html stream, though - does anyone
have any strategies / code samples to get me going?

Thanks,

JON
 
V

vMike

Try something along these lines. I haven't tested this but it should point
you in the right direction


Protected Overrides Sub Render(ByVal writer As HtmlTextWriter)

Dim _stringBuilder As StringBuilder = New StringBuilder()
Dim _stringWriter As StringWriter = New StringWriter(_stringBuilder)
Dim _htmlWriter As HtmlTextWriter = New HtmlTextWriter(_stringWriter)
MyBase.Render(_htmlWriter)
Dim html As String = _stringBuilder.ToString()

'here is where you can manipulate or save the html string

writer.Write(html)

End Sub
 
S

Scott M.

You know, ASP.NET's OutputCache directive is VERY powerfull and does what
you are looking for. Check it out first.
 
J

Jon Maz

Hi All,

Thanks for the replies.

I really *do* need to cache entire pages of html/javascript to a db - the
number of pages involved is too great to cache in server memory, which is
what (if I understand correctly) the built-in asp.net caching does. So it
looks like I need some kind of custom solution here (feel free to correct me
if I'm wrong about this).

The site, which is for a publishing company, will use a Content Management
System to input dynamic content directly into the db. When the CMS user (a
journalist) is creating new page content via the CMS, he should have the
option to cache this new page immediately, ie before any site user has
viewed the .aspx page in a browser.

Now I'm really not sure how to go about this. An aspx page has a public
RenderControl method - should I be looking to use that somehow?

Any help appreciated,

Cheers,

JON

PS Also I'm not sure what the machine.config ProcessModel can do for me
(Jayson's suggestion in microsoft.public.dotnet.framework). Can anyone
elucidate?
 
K

Kevin Spencer

Here's the thing, Jon. ASP.Net was architected in a certain way, and runs
optimally when you use it that way. If you want to redesign the entire
architecture, you're certainly free to do so. You can build your own
HttpHandler if you want, starting all the way from the bottom. The CLR has
everything you need.

You think your app is too big for ASP.Net to handle the way it is designed?
Think again. Microsoft uses it on their web site. It was designed for
immense scalability. If you use it the way it was designed to be used, it
will certainly scale to your needs without you having to re-write the
platform.

--
HTH,
Kevin Spencer
..Net Developer
Microsoft MVP
Big things are made up
of lots of little things.
 
J

Jon Maz

Hi Kevin,

You may well be right, but unfortunately the design of the app is not going
to be my decision! The company is porting an existing web app / CMS from
Classic Asp into asp.net, and the Classic Asp version cached html/javascript
strings into a db. They've told me to go and find out how to replicate this
in asp.net.

If I *also* come back with some brand new ideas about new caching methods
that might serve better, then great, but my boss won't be too amused if I
tell him I simply have no idea how to replicate this existing caching
technique that always worked well for them. In fact the starting point of
my research was (of course) the built-in caching objects in .net. My boss's
response to articles on asp.net Caching (like
http://aspnet.4guysfromrolla.com/articles/022802-1.aspx) was to say "we have
over 30,000 articles to display on our site, you can't keep all that in
server memory".

Perhaps I/he misunderstand how asp.net caching works, and it *doesn't* work
by storing all cached data (in this case, 30,000+ articles) in memory. If
so, great - maybe someone can explain to me how it does work.

But anyway, the task I've been given is find out how to cache
html/javascript strings into a db using asp.net. Is it really the case that
I'd have to build my own HttpHandler to do this?! Hope not....

Thanks for the help so far,

JON
 
V

vMike

Jon,
The code I provide in my previous post above will give you the actual
html/javascript of the rendered page which you can save to a database. The
remaining task of calling the page from the database instead of
re-renderering the page would have to be built but could be based on the
parameters of the data you save the database.
 
J

Jon Maz

Hi Mike,

Thanks for that, I'll see what I can do on the basis of your code snippet.
Do you have any suggestions for how to call the page from the db?

The other thing I'm currently musing on is how to access the different html
streams for different browsers. Do you know at what point the
HtmlTextWriter checks which browser it is producing html for, and can you
"pass a browser type as a parameter" to it?

Thanks again,

JON
 
V

vMike

Your task sounds daunting and the potential for problems seems high. It may
be worth doing some benchmarking with test data and see if reading from the
database is faster than creating the pages on the fly. You might also do
some testing with the built in cache (Remember that you can cache the data
source, in whole or in part, and lots of other things like controls as well
as caching output pages). Maybe those test might be useful in convincing
others that the approach in dotnet should be different than asp. I don't
have enough experience to tell you which way to go on it, but you should be
able to use the code to save some pages and show that it can be done and you
can use that info to do the testing. There are a lot of others on the
newsgroup with a lot of experience that may have futher input.

Good Luck
 
E

Eric Newton

....continuing the debate...

Jon, caching the final output back to the db is putting even MORE strain on
the database machine... even if you use a caching server, ie a completely
separate database machine to hold the cached pages, you'll still never reach
local, in-memory caching performance.

Scalability of that solution is similar, however, IMO buying more RAM for
web servers and adding more webservers to the front line is a lot cheaper
and easier to maintain system then forcing a database backend to cache the
result.

Your client should respect your knowledge in .Net, and acknowledge the fact
that ASP.Net is almost completely different from Classic ASP, and in some
cases is over 10 times faster, even before using caching of any type...

....just my two cents...
 

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