How to check if browser caching disabled - c#

Is there a way in either Javascript or C# to tell if the browser that someone is using has disabled caching of static content?
I need to be able to test whether or not the browser is optimized for caching.

UPDATE
I did a bit more investigation of the problem and you can find more detailed answer in my recent post
Note, the solution described below (initially) is not cross browser solution.
Not sure if it helps, but you can try the following trick:
1. Add some resource to you page, let's say it will be javascript file cachedetect.js.
2. The server should generate cachedetect.js each time someone request it. And it should contain cache-related headers in response, i.e. if browser's cache is enabled the resource should be cached for long time. Each cachedetect.js should look like this:
var version = [incrementally generated number here];
var cacheEnabled; //will contain the result of our check
var cloneCallback;//function which will compare versions from two javascript files
function isCacheEnabled(){
if(!window.cloneCallback){
var currentVersion = version;//cache current version of the file
// request the same cachedetect.js by adding <script> tag dynamically to <header>
var head = document.getElementsByTagName("head")[0];
var script = document.createElement('script');
script.type = 'text/javascript';
script.src = "cachedetect.js";
// newly loaded cachedetect.js will execute the same function isCacheEnabled, so we need to prevent it from loading the script for third time by checking for cloneCallback existence
cloneCallback = function(){
// once file will be loaded, version variable will contain different from currentVersion value in case when cache is disabled
window.cacheEnabled = currentVersion == window.version;
};
head.appendChild(script);
} else {
window.cloneCallback();
}
}
isCacheEnabled();
After that you can simply check for cacheEnabled === true or cacheEnabled === false after some period of time.

I believe this should work: http://jsfiddle.net/pseudosavant/U2hdy/
Basically you have to preload a file twice and check how long it took. The second time should take less than 10ms (in my own testing). You will want to make sure the file you are testing is sufficiently large that it takes at bit to download, it doesn't have to be huge though.
var preloadFile = function(url){
var start = +new Date();
var file = document.createElement("img");
file.src = url;
return +new Date() - start;
};
var testFile = "http://upload.wikimedia.org/wikipedia/en/thumb/d/d2/Mozilla_logo.svg/2000px-Mozilla_logo.svg.png"
var timing = [];
timing.push(preloadFile(testFile));
timing.push(preloadFile(testFile));
caching = (timing[1] < 10); // Timing[1] should be less than 10ms if caching is enabled

Another approach that involves client and server.
Make a call to a page/endpoint, which will set a random unique id in response. Set the cache header for this page/endpoint
Make the same call again, which will set a different unique number
If the the numbers match it is coming from cache or it is coming from server

Related

ClientBuildManager.PrecompileApplication in Azure not using pre-compiled version

I have added the ClientBuildManager.PrecompileApplicaiton to my Azure web role as described here. The web role will start, however, takes an extraordinary long time (15-20 mins), presumably from the amount of files it has to compile (18K+).
After the role starts, I hit the site, which doesn't appear to be any faster in initial startup.
When I RDP to my web role, I can see 2 separate folders in the Temporary ASP.NET Files, one containing all of my pre-compiled code (3K+ files), the other containing a smaller set of files matching those that would be used during my initial request (50 files).
From what I can tell, the site is pre-compiling, however, the actual requests are not leveraging this pre-compilation and doing a normal on-the-fly compilation as before when a request is made.
After viewing the above, I made another request to a different page within my site and confirmed the folder with 50 files increased to 58 files, telling me it is in fact still doing on-the-fly compiling. The other folder with 3K files remained unchanged.
Here is the code I am using for my pre-compilation in my OnStart method:
var siteName = RoleEnvironment.CurrentRoleInstance.Id + "_Web";
var mainSite = serverManager.Sites[siteName];
var rootVirtualPath = String.Format("/LM/W3SVC/{0}/ROOT/", mainSite.Id);
var clientBuildManager = new ClientBuildManager(rootVirtualPath, null);
clientBuildManager.PrecompileApplication();
Am I missing something else that would force the role to use my pre-compiled files?
Here's the full code that works, note one important difference is to NOT include trailing slash in appVirtualDir
using (var serverManager = new ServerManager())
{
string siteName = RoleEnvironment.CurrentRoleInstance.Id + "_" + "Web";
var siteId = serverManager.Sites[siteName].Id;
var appVirtualDir = $"/LM/W3SVC/{siteId}/ROOT"; // Do not end this with a trailing /
var clientBuildManager = new ClientBuildManager(appVirtualDir, null, null,
new ClientBuildManagerParameter
{
PrecompilationFlags = PrecompilationFlags.Default,
});
clientBuildManager.PrecompileApplication();
}

Detect Document Reload has occured on server

I have an winform/OCX that consumes a qlikview document. We have gotten a patch from QV so that RefreshDocument works in the OCX as the RefreshDocument does in QV application. But the Application shows a nice enabled button when the document has been reload on the server.
Does anyone know what needs to be done to detect that. Either in C# or in macro code or ManagementAPI ?
This is the ReloadDocument Code.
private void button2_Click(object sender, EventArgs e)
{
var myBloodybookmarkHack = "dynaBookmark" + Guid.NewGuid().ToString().Replace("-","");
axQlikOCX1.ActiveDocument.CreateUserBookmark(myBloodybookmarkHack, true);
//axQlikOCX1.OpenDocument(#"qvp://qvSeverName/path/MyDocument.qvw?bookmark=Server\dynaBookmarkb5aa82ae467540fdb0d18bb499044ed9");
axQlikOCX1.RefreshDocument();
axQlikOCX1.ActiveDocument.RecallUserBookmark(myBloodybookmarkHack);
axQlikOCX1.ActiveDocument.RemoveUserBookmark(myBloodybookmarkHack);
}
By suppressing the paint event I get this to run pretty ok. Next patch will include that it keeps the selections (Will be fixed in 11.2 servicerelease 6).
You need to detect if CreateUserBookmark was successfull or not and not restore the bookmark if the creation failed.
This code works in QV 11.2 serviceRelease 5.
The filesystem reads a new modified time when the qvw file is rewritten after load. Assuming the data portion of this application is not broken out from the QVW file. Likely, you could come very close to accomplishing this by checking for new timestamps. Alternatively, if logging is enabled in the qvw document you could log read the text file* that QlikView generates to accomplish the same thing.
*The text file writes are delayed sometimes so your file might be refreshed a little bit before the log states that it is.
We ended up using the QV Management api to get the last task reload time
Download the Qv management api demo from QV
This code shows you how to get tasks on a document. Through that you get when "last document reload task" was finished.
private DateTime GetLastDocumentRun(string documentName)
{
string QMS = "http://MyQlikviewserver:4799/QMS/Service";
var client = new QMSClient("BasicHttpBinding_IQMS", QMS);
string key = client.GetTimeLimitedServiceKey();
ServiceKeyClientMessageInspector.ServiceKey = key;
var taskStatusFilter = new TaskStatusFilter();
var clientTaskStatuses = client.GetTaskStatuses(taskStatusFilter, TaskStatusScope.All);
foreach (var taskStatus in clientTaskStatuses)
{
Trace.WriteLine(taskStatus.General.TaskName);
if (taskStatus.General.TaskName.ToLower().Contains(documentName.ToLower()))
{
string fin = taskStatus.Extended.FinishedTime + "";
DateTime finishedTime;
if (DateTime.TryParse(fin, out finishedTime))
return finishedTime;
Logger.ErrMessage("QvManagementApi.GetLastDocumentRun",new Exception("Task finished time did not return a valid datetime value:" + fin));
return DateTime.MinValue;
}
}
return DateTime.MinValue;
}
This is slow, so you should run on a different thread.
Also this does not show if the task is successfully reloaded. We haven't fix that yet but on taskStatus.Extended you have the last log, which you can text parse to get if it was successfully reloaded or not.
If I understand correctly you want to know if a document has finished reloading on a QlikView server right?
I've you OCX application has a constant connection, you could evaluate the ReloadTime() function in the document which would tell you when the document was last reloaded. If you listen for the function and issuing a DocumentRefresh while doing this, then you would get a changed timestamp once the newly reloaded document becomes avaible on the server.
The code your posting, does not reload a QlikView document. At least not in QlikView lingo, it just open the documents on the server.
Please elaborate if I misunderstand you.
Regards Torber

Change Background image every visit

I have about 50 background images for my site. What i am looking to do is randomly present the user with a different one for every visit. By this i mean they will surf through the site with the same background image during their visit.
After they close the browser and re-visit or come back and visit later, they then are presented with a new random background image. Don't need to save anything on what their previous background image was, just a random new one for each new visit to the site.
Not sure it this can be done with C#, Javascript, JQuery or CSS.
EDIT: I am using ASP.net 4.0 C# for my web app. Thanks
Don't use cookies as stated in the comments. This will only add extra bandwidth to the header messages sent to the server.
Instead, use local storage in the browser to save what the last image was they used. When a new session is started increment this value, and display the next image.
I've used jStorage on projects and it works fine.
You can save the currently shown image in their browsers storage, and maybe a session ID. Later, you can check if the session ID has changed. If so, then change to a different image.
var image = $.jStorage.get("image", 0);
var session_id = $.jStorage.get("session", "put current session id here");
if(session_id != "current session id")
{
image = (image < 50) ? 0 : image+1;
$.jStorage.set("image",image);
$.jStorage.set("session","current session id");
}
// use image to set background
EDIT:
Don't place this JavaScript in each web page. Instead, place it in a ASP.NET page that responses as a Javascript content type and load it via the page's header. This way page caching on the browser won't affect the script when the session changes.
Keep it in the Session. Pick it at random when it's not already in the session, it will stay the same as long as they're at your site -- and next time they come back, they'll get a new one.
For example (my C# is a little rusty):
public getBackground (HttpSessionState session) {
String bg = (string) session["session.randomBG"];
if (bg == null) {
// pick a random BG & store it.
bg = "pick one";
session["session.randomBG"] = bg;
}
return bg;
}
Hope this helps!
var list = [
"/images01.png",
"/images02.png",
...
];
/*background url*/ = list[Math.floor(Math.random()*list.length];
Sure it is possible. I will use pseudo-code here to show you how it could be done. Surely soon examples in Java will appear.
In the beginning of each page:
StartSession()
If ! SessionVariable[myBackground] then
x=Randomize 50
SessionVariable[myBackground]="image0" + x + ".jpg"
endif
<style>
body {background-image:url(SessionVariable[myBackground];}
</style>
Make sure you use the style tag where appropriate. The SessionVariable[myBackground] is user-created. In PHP it would look like this:
$_SESSION['myBackground']
Best wishes,
Try this function:
/**
* Change background image hourly.
* Name your images with 0.jpg, 1.jpg, ..., 49.jpg.
*/
function getBackground2() {
var expires = 3600000,
numOfImages = 50,
seed = Math.round(Date.now() / expires % numOfImages);
return '/path/to/background/' + seed + '.jpg';
}

how can I use js/coffee to screen scrape an asp page?

I've got a website that I'd like to pull data from and it's really stuck in the stone ages. There's no web service, no API and it's very much an ASP/Session/table-based-layout page. Pretty fugly.
I'd like to just screen scrape it and use js (coffeescript) to automate that. I wonder if this is possible. I could do this with C# and linqpad but then I'm stuck parsing the tables (and sub-tables and sub-sub-tables) with regex. Plus if I do it with js or coffeescript I'll get much more comfortable with those languages and I'll be able to use jQuery for pulling elements out of the DOM.
I see two possibilities here:
use C# and find a library that will do things like Jquery but in C# code
use coffeescript (js) and use jquery to find the elements that I'm looking for in the page
I'd also like to automate the page a bit (get next set of results). This is strictly for personal use -- I'm not pulling results of someone's search to use in my business. I just want to make a crappy search engine do what I want.
I wrote a class that allows you to supply a bunch of urls and a code block to scrape pages inside a chrome extension. You can find the github repo here: https://github.com/jkarmel/Executor. It could use some more testing and I need to work on the documentation, but it looks like it might be what you are looking for.
Here is how you would use it to get the all the links from a few different pages:
/*
* background.js by Jeremy Karmel.
*/
URLS = ['http://www.apple.com/',
'http://www.google.com/',
'http://www.facebook.com/',
'http://www.stanford.edu'];
//Function will be provided to exector to collect information
var getLinks = function() {
var links = [];
var numLinks = $('a');
$links.each(function(i, val) {links.push(val.href)});
var request = {data: links, url: window.location.href};
chrome.extension.sendRequest(request);
}
var main = function() {
var specForUsersTopics = {
urls : URLS,
code : getLinks,
callback : function(results) {
for (var url in results) {
console.log(url + ' has ' + results[url].length + ' links.');
var links = results[url];
for (var i = 0; i < links.length; i++)
console.log(' ' + links[i]);
}
console.log('all done!!!!');
}
};
var exec = Executor(specForUsersTopics);
exec.start();
}
main();
So basically the code to collect the links would be supplied to the executor instance and then you would do whatever you wanted with the results in the callback. It can deal with longish lists of url (~1000) and it will work on more than one at a time (default == 5). It doesn't handle errors in the code block very well right now, so be sure to test the code you are supplying.
I'm liking Curtain A) "use C# and find a library..."
"HTML Agility Pack" might be just what you're looking for:
http://htmlagilitypack.codeplex.com/
You can do it easily with Node.js, jsdom, and jQuery. See this tutorial (in JavaScript).

Selenium 2 WebDriver - Chrome - Getting the value from a text box that is set via JavaScript

I am using Selenium 2 (latest release from Googlecode) and I have it firing up Chrome and going to a url.
When the page has loaded some javascript executes to set the value of a textbox.
I tell it to find a textbox by id which it does but it doesn't have the value within it (if I hardcode a value it finds it).
Looking at the PageSource e.g. Console.WriteLine(driver.PageSource); shows the html and the textbox is empty.
I've tried using :
driver.FindElement(By.Id("txtBoxId") to get the element and that too doesn't fetch the value.
I've also tried ChromeWebElement cwe = new ChromeWebElement(driver, "txtBoxId"); (which complains about Stale data).
Any thoughts?
John
Finally I found the answer! This is the code that works for me
WebDriverWait wait = new WebDriverWait(_driver, new TimeSpan(0,0,60));
wait.Until(driver1 => _driver.FindElement(By.Id("ctl00_Content_txtAdminFind")));
Assert.AreEqual("Home - My Housing Account", _driver.Title);
Here is my source!
http://code.google.com/p/selenium/issues/detail?id=1142
Selenium 2 does not have wait functions built in for elements in the DOM. This was the same thing as in Selenium 1.
If you have to wait for something you could do it as
public string TextInABox(By by)
{
string valueInBox = string.Empty;
for (int second = 0;; second++) {
if (second >= 60) Assert.Fail("timeout");
try
{
valueInBox = driver.FindElement(by).value;
if (string.IsNullOrEmpty(valueInBox) break;
}
catch (WebDriverException)
{}
Thread.Sleep(1000);
}
return valueInBox;
}
Or something along those lines
I use webdriver through ruby (cucumber watir-webdriver, actually), and I tend to do this:
def retry_loop(interval = 0.2, times_to_try = 4, &block)
begin
return yield
rescue
sleep(interval)
if (times_to_try -= 1) > 0
retry
end
end
yield
end
Then whenever I have content appearing due to javascript writes or whatever, i just wrap it in a retry_loop like so:
retry_loop do #account for that javascript might fill out values
assert_contain text, element
end
As you'll notice there is no performance penalty if it is already there. The reverse case (checking that something is NOT there) will always need to reach the timeout, obviously.
I like the way that keeps details packed away in the method and the test code clean.
Perhaps you could use something similar in C++?

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