The company I work for has proxies/WAN accelerators between our international sites to cache Intranet web content. I have a Silverlight application being hosted on a server at one location, but being accessed by clients in another location. When the users access the web page hosting the Silverlight app, they get the stale xap file being cached by the proxy and not the latest version from the server. Local users always get the latest xap as their requests are not going through a proxy.
I've tried the various header/metadata techniques mentioned elsewhere to prevent caching, and the containing web page itself is being served up fresh, but I still get the old .xap file. Short of getting our IT admin to disable proxy caching for my site, is there anything I can do make sure the latest xap file get retrieved from the server instead of the proxy? The containing page is ASP.NET.
What I do is just add a querystring at the end of the path to the xap file. Then when you change the querystring variable, the proxies etc. should see it as a request to a new file. So far this has worked fine for me.
So basically, when embedding an .xap in a straight-up HTML file, you would do this:
<param name="source" value="ClientBin/SilverlightApplication1.xap?cachepreventer=whatevervalue"/>
And then when you deploy a new version, just change "whatevervalue" to something else.
EDIT
If you need to use this technique in many places in your app I would read the querystring value from config and just write it to the page using asp.net. That way you only need to update it in one place when you deploy.
If you want to make sure every time the xap file is retrieved and you don't want to worry about it - just use
<param name="source" value="ClientBin/YourSilverlightapp.xap?<%=Guid.NewGuid().ToString() %>"/>
of course - this lends itself to a heavier cache load. I do like the helper method above though if you only want changes to be propagated to the client.
Related
I am building a react app, which consists in a Single Page Application, hosted on Amazon S3.
Sometimes, I deploy a change to the back-end and to the front-end at the same time, and I need all the browser sessions to start running the new version, or at least those whose sessions start after the last front-end deploy.
What happens is that many of my users still running the old front-end version on their phones for weeks, which is not compatible with the new version of the back-end anymore, but some of them get the updates by the time they start the next session.
As I use Webpack to build the app, it generates bundles with hashes in their names, while the index.html file, which defines the bundles that should be used, is uploaded with the following cache-control property: "no-cache, no-store, must-revalidate". The service worker file has the same cache policy.
The idea is that the user's browser can cache everything, execpt for the first files they need. The plan was good, but I'm replacing the index.html file with a newer version and my users are not refetching this file when they restart the app.
Is there a definitive guide or a way to workaround that problem?
I also know that a PWA should work offline, so it has to have the ability to cache to reuse, but this idea doesn't help me to perform a massive and instantaneous update as well, right?
What are the best options I have to do it?
You've got the basic idea correct. Why your index.html is not updated is a tough question to answer to since you're not providing any code – please include your Service Worker code. Keep in mind that depending on the logic implemented in the Service Worker, it doesn't necessarily honor the HTTP caching headers and will cache everything including the index.html file, as it seems now is happening.
In order to have the app work also in offline mode, you would probably want to use a network-first SW strategy. Using network-first the browser tries to load files from the web but if it doesn't succeed it falls back to the latest cached version of the particular file it tried to get. Another option would be to choose what is called a stale-while-revalidate strategy. That first gives the user the old file (which is super fast) and then updates the file in the background. There are other strategies as well, I suggest you read through the documentation of the most widely used SW library Workbox (https://developers.google.com/web/tools/workbox/modules/workbox-strategies).
One thing to keep in mind:
In all other strategies except "skip SW and go to the network", you cannot really ensure the user gets the latest version of the index.html. It is not possible. If the SW gives something back from the cache, it could be an old version and that's that. In these situations what is usually done is a notification to the user that a new version of the app has been donwloaded in the background. Basically user would load the app, see the version that was available in the cache, and SW would then check for updates. If an update was found (there was a new index.html and, because of that, new service-worker.js), the user would see a notification telling that the page should be refreshed. You can also trigger the SW to check for an update from the server manually from your own JS code if you want. In that situation, too, you would show a notification to the user.
Does this help you?
I'm trying to make a hybrid python-js application with cefpython.
I would like to have:
JS and HTML files local to the cef python app (e.g. in './html', './js', etc)
Load one of the HTML files as the initial page
Avoid any CORS issues with files accessing each other (e.g. between directories)
The following seems to work to load the first page:
browser = cef.CreateBrowserSync(url='file:///html/index.html',
window_title="Rulr 2.0")
However, I then hit CORS issues.
Do I need to run a webserver also? Or is there an effective pattern for working with local files?
Try passing "disable-web-security" switch to cef.Initialize or set BrowserSettings.web_security_disabled.
Try also setting BrowserSettings.file_access_from_file_urls_allowed and BrowserSettings.universal_access_from_file_urls_allowed.
There are a few options in CEF for loading custom content and that can be used to load filesystem content without any security restrictions. There is a resource handler, a scheme handler and a resource manager. In CEF Python only resource handler is currently available. There is the wxpython-response.py example on README-Examples.md page.
Resource manager is a very easy API for loading various content, it is to be implemented in Issue #418 (PR is welcome):
https://github.com/cztomczak/cefpython/issues/418
For scheme handler see Issue #50:
https://github.com/cztomczak/cefpython/issues/50
Additionally there is also GetResourceResponseFilter in upstream CEF which is an easier option than resource handler, to be implemented via Issue #229:
https://github.com/cztomczak/cefpython/issues/229
You could also run an internal web server inside your app (easy to do with Python) and serve files that way. Upstream CEF also has a built-in web server functionality, however I don't think this will be exposed in cefpython, as it's already easy to set up web server in Python.
I would like to accesss the sitecore DB and items from console application like
Sitecore.Data.Database db = Sitecore.Context.Database
or
Sitecore.Data.Database db = Sitecore.Data.Database.GetDatabase("master")
how do I configure and setup my console application to access the DB as above?
Thanks Everyone for the suggestion, I am really interested in config changes, I used webservice, but it has very limited methods. For example, if I would like create an Item with the template and insert the item with prepopulated value, there is no such option. The reason I am looking for the console apporach is I would like to import the contents from XML or excel sheet and push those to the sitecore tree, eventually use the scheduled task to run the console app periodically. I do not want to copy the entire web.config and app_config. If anyone has already done this, could you please post your steps and necessary config changes?
You have two options I think:
1) Import the Sitecore bits of a website's web.config into your console application's app.config, so that the Sitecore API "just works"
I'm sure I read a blog post about this, but I can't find the reference right now. (I will have another look) But I think the simple but long winded approach is to copy all of the <sitecore/> element and all the separate files it references. I'm fairly sure you can whittle this down to a subset of the config required for data access with a bit of thinking.
2) Don't use the Sitecore API directly, connect to a web service that exposes access to it remotely.
There are a few of these that already exist. Sitecore itself exposes one, Sitecore Rocks has one, and Hedgehog TDS has one too. And you can always write your own (since any web service running inside the Sitecore ASP.Net app can make database calls and report values back and forth - just remember to consider security if this web service might end up exposed externally for any reason)
John West links to some relevant stuff here:
http://www.sitecore.net/Learn/Blogs/Technical-Blogs/John-West-Sitecore-Blog/Posts/2013/09/Getting-Data-Out-of-the-Sitecore-ASPNET-CMS.aspx
-- Edited to add --
I've not found the blog post I remember. But I came across this SO thread:
Accessing Sitecore API from a CLI tool
which refers to this blog post:
http://www.experimentsincode.com/?p=232
which I think gives the info you'll need for option 1.
(And it reminds me that, of course, when you copy the config stuff you have to copy the Sitecore binaries into your app's folder as well)
I would just like to expand on #JermDavis' post and note that Sitecore isn't a big fan of being accessed when not in a web application. However, if you still want to do this, you will need to make sure that you have all of the necessary configuration settings from the web.config and App_Config of your site in your console application's app.config file.
Moreover, you will never be able to call Sitecore.Context in a console application, as the Sitecore Context sits on top of the HttpContext which means that it must be an application and have a valid request for you to use it. What you are looking for is something more along the lines of Sitecore.Configuration.Factory.GetDatabase("master").
Good luck and happy coding :)
This sounds like a job for the Sitecore Item Web API. I use the Sitecore Item Web API whenever I need to access Sitecore data from the master database outside the context of the Content Management server or outside of the context of the Sitecore application. The Web API definitely does not allow you to do everything that the standard Sitecore API does but it can act as a good base and I now extend upon the Web API instead of writing my own custom web services whenever possible.
Thanks to JemDavis's advise.
After I copied the configuration and made changes to config section to get rid of conflicts. I copied almost all of Sitrecore, analytics and lucene dlls, it worked great.
Only thing you have to remember is, copy the app_config folder to the same location where your dlls are.
Thanks again JemDavis....
I have a Java based web application running on google appengine that depends on data in the datastore. When I update this backend data and deploy. I can see the data change immediately if I access the url 1-dot-myapp.appspot.com. I cannot get the default version of the url (myapp.appspot.com) to update on another device unless I access the full specific version of the url.
How can I force the default version of the application to update on deployment?
Thank you
I went back and looked at my cookies information. 1-dot-myapp.appspot.com only has a _ga cookie, the entry for myapp.appspot.com has 3 cookie values: application cache, ACID, and _ga. I was surprised that 1-dot-myapp.appspot.com did not have an application cache value in the cookie. So now I guess my question is. How can I force the application cache to renew as desired.
What I came up with was to either remove reference to my manifest file from my html or to rename my manifest file. So when ever I want to for the client browser to update the cache I redploy with a newly named manifest file. The manifst file is renamed with a version number like manifest2.mf. Then my build modifies all references for manifest to the newly name manifest file i.e. manifest2.mf. My html files and my appengine.xml file then us manifest2.mf . these changes seem to force the client browsers to update their cache.
I have a silverlight business aplication that gets data from silverlight enabled webservice.
When I run the application in dev environment, it works fine.
when i deploy the application and the Asp.net web development server is working, then to the application works fine.
But when I stop the development server, the application can't access a service.
My questions are:
When I deploy a silverlight business application, doesn't the service get deployed and get started.
The endpoint address in my ServiceReferences.Clientconfig file is endpoint address="http://localhost:9702/MyWebservice.scv. Do I need to change this?
The enpoint address in the web.config is blank.
Appreciate your help
Because the WCF client code is declared as a "partial" class, what I've been doing to this point is creating another c# partial class file to host a GetClient() method on it. You'll notice that the code is taking into account the port that the service is on... in a few of the environments that I've posted or will be posting to, as well as the development environment, the application is not always on port 80.
Namespace Project.Service
{
public partial class ServiceClient
{
public static ServiceClient GetClient()
{
return new ServiceClient("CustomBinding_Service",
new System.ServiceModel.EndpointAddress(new Uri(string.Format("{0}://{1}:{2}/Services/Service.svc",
Application.Current.Host.Source.Scheme, Application.Current.Host.Source.Host, Application.Current.Host.Source.Port), UriKind.Absolute)));
}
}
}
Hope this helps someone!
Yes you are going to want to change your endpoint address. I recommend doing it in the silverlight code when creating the connection to the WCF service. The service itself lives on the web server, whereas the silverlight application lives on the clients computer. If the web server stops, the web service stops but the silverlight app can keep running.
edit:
To do this in code, as long as the path is always in the same domain as the app you can use do like so:
BasicHttpBinding binding = new BasicHttpBinding(BasicHttpSecurityMode.None) //Use whatever security you need here
{
MaxReceivedMessageSize = int.MaxValue,
MaxBufferSize = int.MaxValue
};
Client client = new Client(binding, new EndpointAddress(new Uri(Application.Current.Host.Source, "../MyService.svc")));
Thanks so much for your help. I tried your approach to create the client code but that didn't work. And that's because the problem seems to be somewhere else.
So I installed fiddler to see the traffic.
Fiddler showed that the service was being accessed but the http response code was 302 showing that there was some redirection involved.
The address of my application is like this http:///Silverlightapp/(S(oirppxrwzhlf2a2vbia1ui45))/Default.aspx#/Home and it is hosted on IIS 6.
So I had to employ a workaround by installing the service on machine with IIS7 (and there was no session id involved like in the above url).I still kept the silverlight application hosted on IIS 6.
Anyway, in summary, to anyone who reads the thread, I did the following to troubleshoot and solve issue(temporarily)
Changed the end point address in the ServiceReferences.ClientConfig file. When you add the service using discover option in VS, the endpoint address is of the localhost and this must be changed.
Registered the service model using ServiceModelReg -i command. (this solved my problem that my applicaiton was only working from development server and not IIS)
-Put the CrossDomain and ClientAccessPolicy files in c:]inetpub\wwwroot folders.
-Used fiddler to look at http response codes. I had to do no configuration in fiddler.
Changed the binarymessageEncoding to textMessageEncoding iin the web.config file of the silverlight web project that also hosted the ecf service. I did this becasue adding a silverlight enabled wcf service creates a custom binding configuration in the web.config file by default uses binary encoding. I needed text encoding to see errors in fidder. But this didn't help much becasue I only saw the name of the operation in the Inspector>xml tab in fiddler. This was the same even after my issues was resolved by workaround.
Thanks for the help
Don't do it in code. Otherwise you won't be able to change it later without recompiling the application (when the address will need to change, perhaps years down the road when you've lost the source code :)
Change the address in ServiceReferences.ClientConfig to where the service is actually hosted... e.g. http://example.com/myVdir/MyWebservice.svc
If later on you need to change the address without recompiling:
- Open the .xap file (it's just a zip file with a different extension)
- Find the .ClientConfig file and change the address
- Put it back together as a .zip file and rename to .xap
Also, I can't remember anymore whether the .ClientConfig supports relative addresses (e.g. just "MyWebService.svc"), but if it does it may be a good solution as well.