I am writing an ASP.NET web page which calls an API to update my client's property website using XML data. The data from the API is real-time, so I would like to run the page every 10 minutes.
Clearly I don't want to load my page manually to keep my client's property website up-to-date. There is a lot of help in Stack Overflow and elsewhere on this type of question but I have become a little overwhelmed by the options. I think that one way to go would be:
Windows Task Scheduler to fire every ten minutes (to trigger a VB.Net Service)
VB.Net Service (to run the web page)
My page runs..
That feels like overkill, and I haven't written a Windows Service or used the Task Scheduler and it feels like there should be 2 steps not three.
Now if I do use a VB.Net Service then I think that it might be better to give more work to the VB.Net Service rather than put my script in a web page, but I am used to writing web pages!
I can't help feeling that if I just keep the page open in a browser somewhere I can easily use JavaScript to run the page every 10 minutes, but that means ensuring it's open in a browser. Bad solution I think...
What I need is an overview of my options to make an informed decision and if it means learning then fine. Thanks in advance!
You can use javascript/Jquery to call a page/webmethod continously in timely manner
setInterval(function() {
// call your page or webmethod
}, 1000 * 60 * x); // x is your time interval in mins, in your case x=10
In my opinion the best approach would be to create a windows service and have the service call the web page. The windows service is much more stable than the Task Scheduler because the task scheduler can overlap if the previous Scheduled event did not finish. Also using the windows service gives you more control over error handling and logging
Get started with this link:
http://code.msdn.microsoft.com/windowsdesktop/CSWindowsService-9f2f568e
Related
I have a mobile application integrated to a server where users can see tasks assigned and close the task request after work. In this project timing is very important, at least ones in a minute program should check if a task is assigned. Moreover mobile should also check the server if there is a change on the task that it already downloaded.
Because of the nature of the project download amount is high. How can we reduce it? Should we use another technology for server communication (Now we use ASP.NET Web Service Application)?
Thanks in advance.
Use JSON instead of XML Server.
Try using selective sync options like instead of complete tasks sync as it would become slow with higher number of tasks.
Mark task changes locally on mobile. mark entities dirty and then only update marked tasks to cloud/Server.
as SLaks suggested use push instead of pull it will save mobile battery and user's data package.
Here is what can help you:
Microsoft Sync Framework.
http://msdn.microsoft.com/en-us/sync/bb887608.aspx
http://weblogs.aspnet05.orcsweb.com/sbehera/archive/2009/04/10/sync-framework-for-windows-mobile-devices-amp-some-use-full-links.aspx
I'm putting together a website that will track user-defined events with time limits. Every user would be free to create events, and when the time limit expired, the server would need to take some action based on the outcome of the event. The specific component I'm struggling with is the time-keeping: think like eBay's auction clock -- it's set to expire at a certain time, clearly runs server-side, and takes some action when the time runs out. Searches for a "server side timer," unfortunately, just bring back results for a timer that gets the time from the server instead of the client. :(
The most obvious solution is to run a script on the server, some program that would watch all the clocks and take action when any of them expired. Tragically, I'll be using free web hosting, and sincerely doubt that I'll be able to find someone who'll let me run arbitrary stuff on their servers.
The solutions that I've looked into:
Major concept option 1: persuade each user's browser to run the necessary timers (trivial javascript), and when the timers expire, take necessary action. The problem with this approach is obvious: there could be hundreds, if not thousands, of simultaneous expiring timers (they'll tend to expire in clusters), and the worst case is that every possible user could be viewing their timer expire. That's a server overload waiting to happen at the worst possible instant.
Major concept option 2: have one really trusted browser, say, a user logged in to the website as "cron" which could run all of the timers at once. The action would all happen in that browser's javascript, and would work great, as long as that browser never crashed, that machine never failed, and that internet connection never went down.
As you can see, I feel like I'm barking up the wrong forest on this problem. Some other ideas that have presented themselves:
AJAX: I'm not seeing anything here that will do quite what I need. It's all browser-run stuff, nothing like a server-side process that could run independent of the user's browser.
PHP: Runs neatly on the server, but only in response to client requests. I'm not seeing any clean way to make PHP fork off a process and run a timer independent of the user's browser.
JS: same problems as PHP, but easier to read. ;)
Ruby: There may be some multi-threading with Ruby, but it isn't readily apparent to me. Would it be possible to have each user's browser check to see if a timer process was running for their event, and spawn a new server-side ruby process if it wasn't?
I'm wide open for ideas -- I've started playing with concepts in JS and PHP, but I'm not tied to any language, particularly. The only constraint, really, is that I won't own the server that I'm running the site on, so I can't just run a neat little local process that does what I need it to do. :(
Any thoughts? Thanks in advance,
Dan
ASP.NET has multi-threading. You can have a static variable to collect the event data, and use a thread to do whatever needed when the time comes. After you can empty the static variable so it's ready for future use.
http://leedale.wordpress.com/2007/07/22/multithreading-with-aspnet-20/
You might want to take a look at the Quartz scheduler for Java which also has a .NET version. With a friendly open source license (Apache 2.0) this is probably a very good starting point.
If you can control cron jobs, which at least I could on HostPapa's shared hosting, you could run a php file every second which checks the timers and takes action based on them.
I would suggest AJAX anyway, what we did on a game server was emulation of "server connects to client" via AJAX request to server without any time-out (asynchronous connection). Basically you create one extra connection for each client that hangs on the server and waits for the server to take self-invoked action. After the action is done you start a new hanging connection immediately so you have one hanging all the time (so the server can talk to your client any time it wants). You can send javascript code from the server that will decide what will happen next. You can check clients to have these hanging connections on the server side to count as valid and of course run your timers on the server.
I want to build the following back-end service:
For each call to the service, spawn a web browser that loads a webpage (including flash) and returns a screenshot of the page to the caller at intervals (ie every 3 seconds) until the caller disconnects. This needs to scale for many callers (thousands perhaps), each of which needs its own browser session.
When I decided I needed to build this program, I was surprised that I had basically no idea how I could do it.
On stackoverflow, I found the following link which looks promising: http://www.genuitec.com/about/labs.html
Any other ideas?
You can use XULRunner (Mozilla engine) on your server side. I'm in doubt though that this solution is scalable.
I am developing a Windows Phone app where users can update a list. Each update, delete, add etc need to be stored in a database that sits behind a web service. As well as ensuring all the operations made on the phone end up in the cloud, I need to make sure the app is really responsive and the user doesn’t feel any lag time whatsoever.
What’s the best design to use here? Each check box change, each text box edit fires a new thread to contact the web service? Locally store a list of things that need to be updated then send to the server in batch every so often (what about the back button)? Am I missing another even easier implementation?
Thanks in advance,
Data updates to your web service are going to take some time to execute, so in terms of providing the very best responsiveness to the user your best approach would be to fire these off on a background thread.
If updates not taking place (until your app resumes) due to a back press is a concern for your app then you can increase the frequency of sending these updates off.
Storing data locally would be a good idea following each change to make sure nothing is lost since you don't know if your app will get interrupted such as by a phone call.
You are able to intercept the back button which would allow you to handle notifying the user of pending updates being processed or requesting confirmation to defer transmission (say in the case of poor performing network location). Perhaps a visual queue in your UI would be helpful to indicate pending requests in your storage queue.
You may want to give some thought to the overall frequency of data updates in a typical usage scenario for your application and how intensely this would utilise the network connection. Depending on this you may want to balance frequency of updates with potential power consumption.
This may guide you on whether to fire updates off of field level changes, a timer when the queue isn't empty, and/or manipulating a different row of data among other possibilities.
General efficiency guidance with mobile network communications is to have larger and less frequent transmissions rather than a "chatty" or frequent transmissions pattern, however this is up to you to decide what is most applicable for your application.
You might want to look into something similar to REST or SOAP.
Each update, delete, add would send a request to the web service. After the request is fulfilled, the web service sends a message back to the Phone application.
Since you want to keep this simple on the Phone application, you would send a URL to the web service, and the web service would respond with a simple message you can easily parse.
Something like this:
http://webservice?action=update&id=10345&data=...
With a reply of:
Update 10345 successful
The id number is just an incrementing sequence to identify the request / response pair.
There is the Microsoft Sync Framework recently released and discussed some weeks back on DotNetRocks. I must admit I didnt consider this till I read your comment.
I've not looked into the sync framework's dependencies and thus capability for running on the wp7 platform as yet, but it's probably worth checking out.
Here's a link to the framework.
And a link to Carl and Richard's show with Lev Novik, an architect on the project if you're interested in some background info. It was quite an interesting show.
While building this web service and the app that calls it, we have noticed that the first call to the web service each day is extremely slow. It even will time out on some days. However, every call after that work great. Can anybody shed light on why this might be and how we can get rid of this pain?
Thanks in advance!
If it's an ASP.NET web service, it may be the CLR initializing and loading and verifying the assemblies for the first time. You may want to consider pre-compilation
Agree with the other answers on caching, initialization, etc. As far as a workaround, one possibility may be to set up some sort of daily task (SQL Server job, Windows service, something else?) to simulate a hit to the service each day, so that your users don't experience this first slow request.
If it is an ASP.NET web service, then you might want to check the settings of the application pool the web service is running in, especially the idle timeout which defaults to 20 minutes in IIS7.
Configuring IIS7 idle-timeout
Even if it is not an ASP.NET web service, other web servers will have equivalent configuration settings you have to tweak to keep your web service alive overnight.
Can you duplicate the same behavior on your database? It could just be the db needing to optimise the query for the first run (Maybe the parameter is today's date?).
Are there a lot of static constructors or set up code in the Global.asax class? Because IIS recycles worker processes periodically, the start up code may be running again.
The rule for optimization is: don't guess. Put in profiling to find out exactly what is slow, and then work to make that faster. Everything already posted provides excellent tips on where to start looking for slowness.