Alert the host about any updates

Question

Alert the host about any updates

I am currently working on an ASP.NET application that is hosted by a C# application using WebBrowser. The ASP.NET application runs within the C# application environment.

My challenge lies in finding a way to notify the C# application when certain events, such as button clicks, occur. It seems like utilizing Javascript would be the most suitable approach. However, the issue I'm facing is that the only URL visible to the C# application is /Default.aspx. Therefore, all JavaScript functions (e.g., window.external.myfunc(..)) must be accessed from this page.

Do you have any suggestions or ideas? I've hit a roadblock and could use some guidance. Additionally, I'm unsure about how to invoke JavaScript functions from the code-behind. I've seen ScriptManager.RegisterClientScriptBlock being used frequently, but can it be called multiple times on a single page?

Thank you in advance for your help!

Just to provide more context, I am using WebBrowser.ObjectForScripting in the C# client to connect with a custom object that handles these window.external function calls from JavaScript. So far, this setup has been effective.

c#javascript asp.net

Answer 1

Answer №1

The section involving ObjectForScripting and window.external is functioning properly.

To execute JavaScript functions from your ASP.NET code, you must utilize ajax calls from the JavaScript. There are two methods to achieve this:

1. Establish a web service and continuously invoke it to monitor any changes (i.e., polling). This approach is straightforward and can be easily implemented, for instance, using jQuery:

$.ajax(...);

Subsequently, trigger your window.external.func() from the callback of that ajax call (if the desired value is returned). Remember, with this method, there will always be a delay as the client needs to poll the server.

2. Establish a persistent connection to the server and push data from the server when it's available. To accomplish this, consider utilizing something like SignalR. This resolves the issue of delay but maintains an open connection, which may introduce other challenges.

Ultimately, the primary factor in choosing between these two methods is your tolerance for delay. If waiting around 15 seconds on average is acceptable, opt for the first method with a polling frequency of 30 seconds. For real-time updates, implement the second method while being mindful of potential issues such as prolonged connections and SignalR's lack of session-state support.

I simply wanted to present these alternatives. Please let me know if anything is unclear.

Answer 2

The section involving ObjectForScripting and window.external is functioning properly.

To execute JavaScript functions from your ASP.NET code, you must utilize ajax calls from the JavaScript. There are two methods to achieve this:

1. Establish a web service and continuously invoke it to monitor any changes (i.e., polling). This approach is straightforward and can be easily implemented, for instance, using jQuery:

$.ajax(...);

Subsequently, trigger your window.external.func() from the callback of that ajax call (if the desired value is returned). Remember, with this method, there will always be a delay as the client needs to poll the server.

2. Establish a persistent connection to the server and push data from the server when it's available. To accomplish this, consider utilizing something like SignalR. This resolves the issue of delay but maintains an open connection, which may introduce other challenges.

Ultimately, the primary factor in choosing between these two methods is your tolerance for delay. If waiting around 15 seconds on average is acceptable, opt for the first method with a polling frequency of 30 seconds. For real-time updates, implement the second method while being mindful of potential issues such as prolonged connections and SignalR's lack of session-state support.

I simply wanted to present these alternatives. Please let me know if anything is unclear.

Alert the host about any updates

Answer №1

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