I have this code
//file Globals.cs in App_Code folder
public class Globals
{
public static string labelText = "";
}
and a simple aspx page which has textbox, label and button. The CodeFile is:
public partial class _Default : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
Label1.Text = Globals.labelText;
}
protected void Button1_Click1(object sender, EventArgs e)
{
Globals.labelText = TextBox1.Text;
}
}
That is when I click on the button the Globals.labelText variable initializes from the textbox; the question is: why when I open this page in another browser the label has that value, which I set by the first browser, that is the static member is common for the every users. I thought that the every request provides in the individual appDomain which created by the individual copy of IIS process. WTF?
Yes you may use static variable to store application-wide data but it is not thread-safe. Use Application object with lock and unlock method instead of static variables.
Take a look at ASP.NET Application Life Cycle Overview for IIS 7.0 and ASP.NET Application Life Cycle Overview for IIS 5.0 and 6.0
No, static in this case is static in that manner only for the lifecycle of the process the request lives on. So this variable will be static the entire time you're processing a single request. In order to have a "static" variable in the manner you describe, you'd have to make it an application variable. Something like this:
//file Globals.cs in App_Code folder
public class Globals
{
// I really recommend using a more descriptive name
public static string LabelText
{
get
{
return Application("LabelText") ?? string.Empty;
}
set
{
Application("LabelText") = value;
}
}
}
By making it an application variable it should survive multiple page requests. A vulnerability it has though is that it will not survive an application pool recycle, and for large applications this can be problematic. If you truly want this variable to behave in a static manner reliably you're probably better off storing its state in a database somewhere.
Related
Last few days I thinkin about output cache in asp.net. In my task I need to implement output cache for the very big project. After hours of searching I did not find any examples.
Most popular way to use output cache is declarative, in this case you need to write something like this on the page which you want to cache.
But if you need to cache whole site you must write this on all pages or master pages on project. It is madness. In this case you cant store all configuration in one place. All page have his own configurations..
Global.asax could help me, but my site contains about 20 web progects and ~20 global.asax files. And i don't want copy same code to each project.
For these reasons, i made decision to create HTTPModule.
In Init method i subscribe to two events :
public void Init(HttpApplication app)
{
app.PreRequestHandlerExecute += new EventHandler(OnApplicationPreRequestHandlerExecute);
app.PostRequestHandlerExecute += new EventHandler(OnPostRequestHandlerExecute);
}
In method "OnPostRequestHandlerExecute" I set up output caching parameters for each new request :
public void OnPostRequestHandlerExecute(object sender, EventArgs e)
{
HttpApplication app = (HttpApplication)sender;
HttpCachePolicy policy = app.Response.Cache;
policy.SetCacheability(HttpCacheability.Server);
policy.SetExpires(app.Context.Timestamp.AddSeconds((double)600));
policy.SetMaxAge(new TimeSpan(0, 0, 600));
policy.SetValidUntilExpires(true);
policy.SetLastModified(app.Context.Timestamp);
policy.VaryByParams.IgnoreParams = true;
}
In "OnApplicationPreRequestHandlerExecute" method I set calback method to cache validation:
public void OnApplicationPreRequestHandlerExecute(object sender, EventArgs e)
{
HttpApplication app = (HttpApplication)sender;
app.Context.Response.Cache.AddValidationCallback(new HttpCacheValidateHandler(Validate), app);
}
And last part - callback validation method :
public void Validate(HttpContext context, Object data, ref HttpValidationStatus status)
{
if (context.Request.QueryString["id"] == "5")
{
status = HttpValidationStatus.IgnoreThisRequest;
context.Response.Cache.AddValidationCallback(new HttpCacheValidateHandler(Validate), "somecustomdata");
}
else
{
status = HttpValidationStatus.Valid;
}
}
To attach my HttpModule I use programmatically attach method :
[assembly: PreApplicationStartMethod(typeof(OutputCacheModule), "RegisterModule")]
This method works perfectly, but I want to know is there other ways to do this.
Thanks.
Try seeing if IIS caching provides what you need.
http://www.iis.net/configreference/system.webserver/caching
I have written a static class and suppose to share it's members between all sessions. it works for all the browsers running on the same cumputer but the data is not shared between different users from different location. my website is written with ASP.NET
this is my class
public static class GlobalPool
{
public static List<string> OnlineUsers;
}
and I instantiate the OnlineUSers property in Global.asax as
void Application_Start(object sender, EventArgs e)
{
// Code that runs on application startup
GlobalPool.OnlineUsers = new List<string>(100);
}
I add username whenever a user logs into my website:
public void Login(int aMemberSerial)
{
User = new MemberDataAccess().Read(aMemberSerial);
new MemberDataAccess().Login(User);
GlobalPool.OnlineUsers.Add(User.Username);
Message = PostBusiness.NewPost(User);
}
This is not robust code. ASP.NET application routinely recycle (the App Pool) and so all your data will go away.
The best way to approach this is to store the list in a database, and when a Session expires, remove that user from the data store.
I am looking at a legacy enterprise application, which written using ASP.NET. No controls or web forms. This is how it works:
EmployeeList.aspx:
<%# Page Language="C#" AutoEventWireup="true" CodeFile="EmployeeList.aspx.cs" Inherits="EmployeeList" %>
EmployeeList.aspx.cs:
protected void Page_Load(object sender, EventArgs e)
{
// Security Check
// Load Template, get version 1.4 of active employee list
StringBuilder template = GetTemplate("Employee", "ActiveList", "1.4", true);
// Get list from database
using(SqlDataReader objReader = GetListFromDB())
{
while(objReader.Read())
{
//fills data
TUtils.Replace(template, ROW, "%name%", objReader[0]);
}
}
// return response
Response.Write(template.ToString());
}
private StringBuilder GetTemplate(string x, string y, string v, bool z);
{
// returns template
}
private SqlDataReader GetListFromDB() {
// returns data reader
}
My question is, since we are not using web forms, is there a way to introduce NUnit in this event driven model (as shown above)?
Also, please avoid suggestions to move to ASP.NET MVC or other patterns, which we are considering, but wondering is there any way to convert this enterprise application testable.
This is absolutely possible. You should have a look on implementing MVP pattern with ASP.NET Webforms. There are several open source implementations but you can do a smaller specialized on your your own.
The basics are to move your code behind logic to a presenterclass. The presenter class has a reference to the page implementing an interface. The trick in your case will be to Mock the Page.Response object for your test. Thats why it´s hard to unit test it right way. The PageResponse Property contains a object deriving from HttpResponseBase and that´s the baseclass you should Mock in your tests and do your asserts on with your example. You could start with that and then extend your presenter with functionalty like Session, Request etc.
If you don´t have any markup at all probably you can just create the presenter in the view constructor and don´t bother of having and reference to the view.
To clarify: The big trick is to get the code out of the aspx.cs file. That beast is not testable.
Sample base class for Presenters:
public class Presenter<T> where T : class, IView
{
protected readonly T View;
protected Presenter(T view, ILogger logger)
{
View = view;
}
public virtual void page_PreRender(object sender, EventArgs e)
{
}
public virtual void page_Init(object sender, EventArgs e)
{
}
public virtual void page_Load(object sender, EventArgs eventArgs)
{
}
public HttpContextBase HttpContext { protected get; set; }
protected HttpRequestBase Request
{
get { return HttpContext.Request; }
}
}
Since most of your code is in the code-behind, I dont think that the usual testing approach with NUnit / Visual Studio testing framework will work well.
However, I think one possible approach is to use UI Testing frameworks like WATIN / Selenium. This will enable you to still write tests for the various functionality.
I have done something similar in the past by basically writing a test case for every UI action that results in a server postback. May not be ideal but it does allow you to automate your testing.
I'm reading two values from the web.config in the Application_Start of my Global.asax.cs. The string values from the web.config are assigned to their public properties, also defined in the Global.asax.cs .
How do I access the properties in the global.asax.cs file from another class, method, and namespace?
Update #1
This is more complicated than I thought (or maybe I'm just making it complicated). The class where I want to reference these properties in a plain ol' class library and I don't have access to httpcontext (or I don't know how to access it).
Cast the current application instance to your Global type and access the properties there.
var app = (Your.App.Namespace.Global)HttpContext.Current.ApplicationInstance;
var x = app.YourProperty;
If the Global.asax.cs doesn't manipulate the values, then simply read the values from the web.config like you already do in global.asax.cs.
However, if the Global.asax.cs does manipulate the values, then you could write the values into the "Application" object.
void Application_Start(object sender, EventArgs e)
{
// Code that runs on application startup
Application.Add("Foo", "Bar");
}
Lastly, you can mark the property you want to expose from the Global as static.
public static string Abc { get; set; }
void Application_Start(object sender, EventArgs e)
{
// Code that runs on application startup
Abc = "123";
}
I am working on a project management web application. The user has a variety of ways to display a list of tasks. When viewing a list page, they click on task and are redirected to the task edit page.
Since they are coming from a variety of ways, I am just curious as to the best way to redirect the user back to the calling page. I have some ideas, but would like to get other developers input.
Would you store the calling url in session? as a cookie? I like the concept of using an object handle the redirection.
I would store the referring URL using the ViewState. Storing this outside the scope of the page (i.e. in the Session state or cookie) may cause problems if more than one browser window is open.
The example below validates that the page was called internally (i.e. not requested directly) and bounces back to the referring page after the user submits their response.
public partial class _Default : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
if (Request.UrlReferrer == null)
{
//Handle the case where the page is requested directly
throw new Exception("This page has been called without a referring page");
}
if (!IsPostBack)
{
ReturnUrl = Request.UrlReferrer.PathAndQuery;
}
}
public string ReturnUrl
{
get { return ViewState["returnUrl"].ToString(); }
set { ViewState["returnUrl"] = value; }
}
protected void btn_Click(object sender, EventArgs e)
{
//Do what you need to do to save the page
//...
//Go back to calling page
Response.Redirect(ReturnUrl, true);
}
}
This message my be tagged asp.net but I think it is a platform independent issue that pains all new web developers as they seek a 'clean' way to do this.
I think the two options in achieving this are:
A param in the url
A url stored in the session
I don't like the url method, it is a bit messy, and you have to remember to include the param in every relevent URL.
I'd just use an object with static methods for this. The object would wrap around the session item you use to store redirect URLS.
The methods would probably be as follows (all public static):
setRedirectUrl(string URL)
doRedirect(string defaultURL)
setRedirectUrl would be called in any action that produces links / forms which need to redirect to a given url. So say you had a projects view action that generates a list of projects, each with tasks that can be performed on them (e.g. delete, edit) you would call RedirectClass.setRedirectUrl("/project/view-all") in the code for this action.
Then lets say the user clicks delete, they need to be redirected to the view page after a delete action, so in the delete action you would call RedirectClass.setRedirectUrl("/project/view-all"). This method would look to see if the redirect variable was set in the session. If so redirect to that URL. If not, redirect to the default url (the string passed to the setRedirectUrl method).
I agree with "rmbarnes.myopenid.com" regarding this issue as being platform independent.
I would store the calling page URL in the QueryString or in a hidden field (for example in ViewState for ASP.NET). If you will store it outside of the page scope (such as Session, global variable - Application State and so on) then it will not be just overkill as Tom said but it will bring you trouble.
What kind of trouble? Trouble if the user has more than one tab (window) of that browser open. The tabs (or windows) of the same browser will probably share the same session and the redirection will not be the one expected and all the user will feel is that it is a bug.
My 2 eurocents..
I personally would store the required redirection info in an object and handle globally. I would avoid using a QueryString param or the like since they could try bouncing themselves back to a page they are not supposed to (possible security issue?). You could then create a static method to handle the redirection object, which could read the information and act accordingly. This encapsulates your redirection process within one page.
Using an object also means you can later extend it if required (such as adding return messages and other info).
For example (this is a 2 minute rough guideline BTW!):
public partial class _Default : System.Web.UI.Page
{
void Redirect(string url, string messsage)
{
RedirectionParams paras = new RedirectionParams(url, messsage);
RedirectionHandler(paras); // pass to some global method (or this could BE the global method)
}
protected void Button1_Click(object sender, EventArgs e)
{
Redirect("mypage.aspx", "you have been redirected");
}
}
public class RedirectionParams
{
private string _url;
public string URL
{
get { return _url; }
set { _url = value; }
}
private string _message;
public string Message
{
get { return _message; }
set { _message = value; }
}
public RedirectionParams(string url, string message)
{
this.URL = url;
this.Message = message;
}
}