Implement a simpler alternative to ApplicationContext.TransactionListener

[vaadin-bot]

Originally by @Artur-

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The context level transaction listener is too complex for most cases.

• It is hard to grasp that the transaction listener is called for all applications belonging to the session.
• The user must manually compare the application parameter to verify the call is relevant for the application
• The transaction listener is called after init and not before which makes it impossible to init an application based on something passed in the servlet request.

Proposed solution:

• Create an additional application level transaction listener
• public interface ApplicationTransactionListener extends Serializable
• public void transactionStart(Object transactionData);
• public void transactionEnd(Object transactionData);
• The transaction listener is called at the start of every request
• If application implements the interface
• Before init() in first UIDL request

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Imported from https://dev.vaadin.com/ issue #3731

[vaadin-bot]

Originally by @Artur-

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Might make it into 6.2

[vaadin-bot]

Originally by @mstahv

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in [10107] added a derived solution of Artus proposition.

Added added HttpServletRequestListener and PortletRequestListener which can be implemented by Application. Application implementing those interfaces will be called with both request and response before "payload" is applied to application and after terminal is done with its response.

With these interfaces it should be easier to implement common TransactionListener tasks + we have better typed arguments for developers. Still we are not polluting basic application with terminal dependent stuff. An example of using cookies below:

public class CookieExample extends com.vaadin.Application implements
        HttpServletRequestListener, PortletRequestListener {

    private HttpServletResponse response;
    private HttpServletRequest request;

    @Override
    public void init() {
        setMainWindow(new Window());

        Button b = new Button("Set cookie");

        b.addListener(new Button.ClickListener() {

            public void buttonClick(ClickEvent event) {
                Cookie cookie = new Cookie("foo", "bar");
                cookie.setMaxAge(60);
                response.addCookie(cookie);
            }
        });

        Button bs = new Button("Get cookie");

        bs.addListener(new Button.ClickListener() {

            public void buttonClick(ClickEvent event) {
                Cookie[] cookies = request.getCookies();
                for (int i = 0; i < cookies.length; i++) {
                    Cookie cookie = cookies[i];
                    if (cookie.getName().equals("foo")) {
                        getMainWindow().showNotification(
                                cookie.getName() + " : " + cookie.getValue());
                    }
                }
            }
        });

        getMainWindow().addComponent(b);
        getMainWindow().addComponent(bs);

    }

    public void onRequestEnd(HttpServletRequest request,
            HttpServletResponse response) {
        this.response = null;
        this.request = null;
    }

    public void onRequestStart(HttpServletRequest request,
            HttpServletResponse response) {
        this.response = response;
        this.request = request;
    }

    public void onRequestEnd(PortletRequest request, PortletResponse response) {

    }

    public void onRequestStart(PortletRequest request, PortletResponse response) {
        // TODO Auto-generated method stub

    }

}

[vaadin-bot]

Originally by @mstahv

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in [10114] ensured start/end to happen in pairs for both new interfaces + transaction listeners