More TMS WEB Core Tips & tricks
Today we want to bring to your attention two totally different TMS WEB Core features. These little tidbits that can bring your TMS WEB Core web client application from good to great. The first is about handling application termination and the second is about getting something more out of TWebStretchPanel. Application termination For long, handling web application termination was simple: it was not really handled. When there was a reason to handle it server side, software developers came up with the concept of sessions. In a nutshell, when a user first requests a HTML page from the server, a session is started and typically a session timer runs. If the users requests a page update or performs another request from the user, the session timer is reset. If the user does nothing or worse, closes the browser, the server timer runs and when it reaches a predefined time, for example 20 minutes, the session is considered closed and thus stopped. We have all experienced the consequences. You decide to go and grab a cup of coffee, meet a colleague in the coffee room, have an interesting talk that of course takes longer than expected and you return to your desk, want to continue using your web application and you are greeted with a session timeout and need to login again. In the world of modern single-page web client applications with stateless REST backend, this is a lot less likely to occur as it is way less likely to have a reason for server side session management. An easy way to look at it, is that the session state is now kept in the client and the web client application will just perform stateless HTTP(s) requests to a backend when data update or retrieval is needed. And still, even in this much more server resource friendly scenario, developers might have a reason to know when the user closes the web application to save something client or server side. To handle this, modern browsers expose the browser window “unload” and “onbeforeunload” JavaScript event. This event is triggered when the browser window is about to be closed or the user leaves the page via navigation. Other than just handling leaving the web client application, it can also be signalled to the user and a confirmation dialog shown to ask if the user really wants to leave. In TMS WEB Core, taking advantage of this is really simple. In your TMS WEB Core web client application, handle the main form’s OnBeforeUnload event. If you wish to show a confirmation dialog, return the confirmation message text via the parameter AMessage. Note that in Google Chrome, a confirmation message will be shown when the message is not empty but it will contain the standard Google text. For the reason, see: https://bugs.chromium.org/p/chromium/issues/detail?id=587940 Here is a code extract that shows the concept. A simple string variable will determine whether some action is needed before closing or not. This string s is empty by default but during application execution can be set (here via a button click). When this string is not empty, it is used to show a prompt when the user wants to close the application via the form.OnBeforeUnload event and in the form.Unload event it can be effectively handled to do a last action before unloading. […]
