CODEWITHSUNDEEP
javaplayframework
user181351
user181351

Reputation:

How can i write a loading page with play framework

I would like to implement a page that be displayed to the user whilst a system command is run. As soon as the command completes the user should be routed to another page.

What are some strategies to implement this?

(A solution without javascript would be ideal)

Upvotes: 6

Views: 687

Answers (1)

mcls
mcls

Reputation: 9784

It can definitely be done. You want to look at Asynchronous programming with HTTP in the documentation, it explains how to do this in a non-blocking way. You will need a little bit of javascript for the redirecting part though.

And I don't know what you mean with "system command" but you probably want to create a job for it, so you can trigger it with a request. You can then poll it until it's finished and then redirect the user. But really the documentation does an infinitely better job at explaining it then I'm doing now.

Here's an example of a controller action where I assume your system command returns some kind of String output for the user. When the Job is completed it will sent a response to the user, thus triggering the success handler in the javascript example.

public static void executeSystemCommand(String input) {
    Promise<String> outputPromise = new SystemCommandJob(input).now();
    String output = await(outputPromise);
    renderText(output);
}

Basically if you're using jQuery's $.ajax you can use the complete event to poll the data (just do the request again if it didn't succeed within the timeout time) and use the success/done event to redirect the user when the application responds to indicate that the "system command" is done running.

Example of a function you could use:

function poll(){
    $.ajax({ 
        url: "/systemcommand", 
        success: function(data){
            // redirect to next page here
            document.location.href = '/output'
        }, 
        complete: poll, 
        timeout: 20000  
    });
};

There is also a great example on long polling in javascript on StackOverflow.

Upvotes: 4

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