Normally i have a static class that reads and writes to HttpContext.Current.Cache
However since adding threading to my project, the threads all get null reference exceptions when trying to retrieve this object.
Is there any other way i can access it, workarounds or another cache i can use?
I've got a page that I'm using as an e-mail template. I'd like to spin off a new thread, take the rendered page, and put it into an e-mail. Is this possible? If so, how? I haven't had luck so far.
View 3 Repliesi have the code for asynchronous call to the database. i execute the sql command into the begin method that will executed onto the separate thread. now i want to execute the another database call asynchronously so that this also execute onto the separate thread. code for one database cal is here....
private SqlConnection con, con1;
private SqlCommand cmd, cmd1;
private SqlDataReader dr, dr1;
protected void Page_Load(object sender, EventArgs e)
{
if (!IsPostBack)
{
AddOnPreRenderCompleteAsync(new BeginEventHandler(Begin),
new EndEventHandler(End)
);
}
}
/////////////BEGIN METHOD
IAsyncResult Begin(object sender, EventArgs e,AsyncCallback cb, object state)
{
string connect = "Data Source=.\SQLEXPRESS;Asynchronous Processing=true;AttachDbFilename=|DataDirectory|\Database.mdf;Integrated Security=True;User Instance=True";
con = new SqlConnection(connect);
con.Open();
cmd = new SqlCommand("SELECT FirstName,LastName,Age,Company,Profile FROM Person",con);
return cmd.BeginExecuteReader(cb, state);
}
//////END METHOD
void End(IAsyncResult ar)
{
dr = cmd.EndExecuteReader(ar);
Label2.Text = System.Threading.Thread.CurrentThread.GetHashCode().ToString();
GridView1.DataSource = dr;
GridView1.DataBind();
}
We have a web site which implements a central HttpSessionState management in App_Code like this:
[code]...
All of this worked fine ultil we needed to implement a time consuming process in a new thread...
In the second thread HttpContext.Current.Session is null (we know its because the current context its different between threads) so everything fails :
Investigating we found that you could pass the session from one thread to another like this:
[code]...
I want to remove checked items from checklistbox (winform control) in class file method which i am calling asynchronously using deletegate. but it showing me this error message:-
Cross-thread operation not valid: Control 'checkedListBox1' accessed from a thread other than the thread it was created on.
i have tried invoke required but again got the same error. Sample code is below:
[code]....
I have an ASP.NET Web Site I am creating in Visual Web Developer 2008 Express using Visual Basic as the language. It is actually a rewrite-with-mods of an existing ASP script and I'm trying to chew what I've bitten off. I created my page with a text box (txtOutput) on it and since the end product is very complex, and it's generally good practice to separate like functions, I have created 4 separate classes in the App_Code section.
My main page is Sync.aspx and has a code file Sync.aspx.vb with it.
One of my code files is SyncDatabases.vb and in it I have created
Public Class SyncDB
In that class I have created some routines such as
Public Function ReadMSDB(ByVal SQLString as string) as Boolean
In this routine I want to put information in my text box txtOutput on the main form (the default - Form1).
My problem is that if I try:
Form1.txtOutput.Text = "Hello world"
or just
txtOutput.Text = "Hello world"
it says Name 'Form1' (or 'txtOutput') is not declared. I am sure I am missing something simple but have no clue what it is. I assume it's the fact that the write command is in a file (class?) outside the file (class?) containing the page itself but I don't know how to address it properly.
I'm wondering how I can go about accessing page controls from a separate class I've made. I've tried a few things I found using google, but no luck :(
What I'm trying to do is keep a function that is used often, in a global class.
The function then accesses a page literal and calls ScriptManager.RegisterStartupScript. I was hoping this is possible, so then this function wouldn't have to be copied to all of the pages.
I have an ASP.Net 4.0 web application which very frequently loads data from the database and does heavy calculations on it. I want to cache this loaded and prepared data in a central cache that can be accessed by every user and computer who uses the application.
Simple use-case:
User 1 accesses webpage, cache is empty, data is loaded/calculated, data is cached
User 2 accesses webpage, cache contains data, data loaded from cache
User 3 accesses webpage, cache contains data, data loaded from cache
User 1 reloads webpage, cache contains data, data loaded from cache
Cache expires
User 3 refreshes webpage, cache is empty, data is loaded/calculated, data is cached
I know that ASP.Net has a built-in cache mechanism. What I don't know is whether it can be shared between different users accessing the site on different computer at the same time. I would also like to know how the system behaves in a web farm environment.
How can we debbug a multi-thread program to see local variables of each thread using visual studio 2008.
View 1 RepliesI'm new to threading and have used it successfully, but limited. I can spawn a thread and have the main thread reference variables in the spawned thread, but I don't know how to allow the spawned thread to reference (and update) variables in the main thread.
Any example threading code I've seen on the web appears to be WAY more complicated than what I do, so I am unable to understand or integrate into my code.
Here is a quick example of how I use threading:
[code].....
I am reading the Asp.net security documentation on msdn.I come across these tow terms and get really confused.
# WindowsIdentity = WindowsIdentity.GetCurrent()
which returns the identity of the security context of the currently executing Win32 thread.
# Thread = Thread.CurrentPrincipal
which returns the principal of the currently executing .NET thread which rides on top of the Win32 thread.
I have a password page and when someone enters an incorrect password I want to simply foil a brute force attack by having
bool isGoodPassword = (password == expected_password);
lock (this)
{
if (!isGoodPassword)
Thread.Sleep(2000);
}
I would expect that this would allow all correct passwords without stalling, but if one user enters a bad password another successful password from a different user would also be blocked. However, the lock doesn't seem to lock across ASP.NET threads.
I want a example of multithreading .i want to use it in a web form not on console.i am using C#.net .and how to use thread.sleep method for a particular thread.
View 5 RepliesI have access to two seperate databases (mySQL) located on two servers. I need to get the data, link the tables on a key field and display the results in a datagrid. My challenge is that if the search criteria changes for the display it affects rows returned from on table and should thus automatically affect the linked table and resulting data returned.
what the best approach would be to achieving this? So far I have set up a dataset with a dataadapter and table for each connection and then linked the tables in the dataset. The problem that I'm having is getting the linked resultsets to work.
On my form I have the datagrid with two Objectdatasources one for each dataadapter and i believe that's where I'm going wrong...
I am beginner to ASP.NET MVC.
We are doing project in Asp.Net MVC and Nhibernate.
How to seperate my project in to layers ? how to design classes ?
should i followany patterns ? repository patterns ?
Is it correct to implement my caching object like this in my controller :
[code]....
And I Use it like this :
[code]....
We have a wfc layer that wraps the business classes and database access and use a client that lives on the database layer. Amongst our group we are attempting to form standards. Some want to have the client call the web method and pass the page they are requesting and the page size. Pass that to the database and then page in SQL Server use RowNum.Some want to cache the full list of objects in http cache on the service tier and page in memory. They concern here is memory use on the server.
Which would be best for a medium number of users with potentially large number of records to manage (say 30K) Is it better to cache them all in memory and work from there or page at the database as the application scales?
What are the "optimal" parameters for creating an AppFabric cache when you will be storing session state in the cache? MSDN Cache-Related Commands
Powershell command line:
New-Cache [-CacheName] <String> [-Eviction <String>] [-Expirable <String>] [-Force [<SwitchParameter>]] [-NotificationsEnabled <String>] [-Secondaries <Int32>] [-TimeToLive <Int64>]
[code]...
Since I don't want my sessions to be removed unless the session has been abandoned either via code or Session Timeout...For eviction, I would think "None" and for expireable, I would think False.I have tested and calling Session.Abandon does remove the object from the cache. I have also tested to see if by extending my session, the session object in cache is also extended. This does seem to work the "correct" way.
We have a data driven ASP.NET website which has been written using the standard pattern for data caching (adapted here from MSDN):
public DataTable GetData()
{
string key = "DataTable";
object item = Cache[key] as DataTable;
[code]...
The trouble with this is that the call to GetDataFromSQL() is expensive and the use of the site is fairly high. So every five minutes, when the cache drops, the site becomes very 'sticky' while a lot of requests are waiting for the new data to be retrieved.
What we really want to happen is for the old data to remain current while new data is periodically reloaded in the background. (The fact that someone might therefore see data that is six minutes old isn't a big issue - the data isn't that time sensitive). This is something that I can write myself, but it would be useful to know if any alternative caching engines (I know names like Velocity, memcache) support this kind of scenario. Or am I missing some obvious trick with the standard ASP.NET data cache?
We are using HttpRuntime.Cache API in an ASP.NET to cache data retrieved from a database.
For this particular application, our database queries feature a LOT of parameters, so our cache keys look something like this:
table=table1;param1=somevalue1;param2=somevalue2;param3=somevalue3;param4=somevalue4;param5=somevalue5;param6=somevalue6... etc...
we have so many parameters that the cache key is several hundred characters long. is there a limit to the length of these cache keys? Internally, it is using a dictionary, so theoretically the lookup time should be constant. However, I wonder if we have potential to run into some performance/memory problem.
I have use Nhibernate in my MVC Project by me known, Nhibernate have cache on Session and Object. now, I want use HttpContext.Current.Cache (system.web) for cache data something in project. my code same that have problem, haven't it. and that's right or wrong.
View 2 RepliesI've got a web application that runs of a state server. It looks like soon it may need to distributed and there will be two web servers behind a load balancer.
This works great for session state but my next challenge is Cache
My application leverages heavily of cache. I understand ASP.Net 4.0 will be offering more here but nothing much has been said about the how too.
There are two challenges that I face
1). Each webserver will have its own copy of cache whereas it would be more efficient to put this to a third server the same as session state is put to state server.
2). The real challenge is keeping cache in sync if a simple dataset derived from the database is changed my code dumps that cache item and reloads the cache. That's all well on one webserver but webserver number two wont know to drop that particular cache item and reload it. This could cause some unexpected problems in the application.
For scenario number 2 I could attempt to do some smart coding so server number two knows to dump the cache and reload it.
My guess is someone else has already been here before and there's probably a better implementation approach rather than writing extra code.
Does anyone know how I could achieve the goal of keeping Cache in sync between multiple webservers or even better farm Cache management to another server?
I need to enable caching in my asp.net application, but I do not want to use the webserver's memory for holding cache objects. If I add the page directive for output caching will the page be stored in the asp.net cache object?
View 2 RepliesI want to be able to maintain certain objects between application restarts.
To do that, I want to write specific cached items out to disk in Global.asax Application_End() function and re-load them back on Application_Start().
I currently have a cache helper class, which uses the following method to return the cached value:
return HttpContext.Current.Cache[key];
Problem: during Application_End(), HttpContext.Current is null since there is no web request (it's an automated cleanup procedure) - therefore, I cannot access .Cache[] to retrieve any of the items to save to disk.
Question: how can I access the cache items during Application_End()?
Im building a image gallery which reads file from disk, create thumbnails on the fly and present them to the user. This works good, except the processing takes a bit time.
I then decided to cache the processed images using the ASP .NET Application Cache. When a image is processed I add the byte[] stream to the cache. As far as I know this is beeing saved into the system memory. And this is working perfect, the loading of the page is much faster.
My question is if there are thousands of images which gets cached in the Application Cache, will that affect the server performance in any way?
