Examples of org.eclipse.jetty.continuation.Continuation

org.eclipse.jetty.continuation.Continuation
e need to get asynchronous results Object results = request.getAttribute("results); if (results==null) { Continuation continuation = ContinuationSupport.getContinuation(request); continuation.suspend(); myAsyncHandler.register(continuation); return; // or continuation.undispatch(); } async wait ... Async Handler: // when the waited for event happens continuation.setAttribute("results",event); continuation.resume(); Filter/Servlet: // when the request is redispatched if (results==null) { ... // see above } else { response.getOutputStream().write(process(results)); }
Suspend/Complete Usage

The suspend/complete style is used when an asynchronous handler is used to generate the response:
```
 Filter/Servlet: // when we want to enter asynchronous mode Continuation continuation = ContinuationSupport.getContinuation(request); continuation.suspend(response); // response may be wrapped myAsyncHandler.register(continuation); return; // or continuation.undispatch(); Wrapping Filter: // any filter that had wrapped the response should be implemented like: try { chain.doFilter(request,wrappedResponse); } finally { if (!continuation.isResponseWrapped()) wrappedResponse.finish() else continuation.addContinuationListener(myCompleteListener) } async wait ... Async Handler: // when the async event happens continuation.getServletResponse().getOutputStream().write(process(event)); continuation.complete() 
```
Continuation Timeout

If a continuation is suspended, but neither {@link #complete()} or {@link #resume()} iscalled during the period set by {@link #setTimeout(long)}, then the continuation will expire and {@link #isExpired()} will return true.

When a continuation expires, the {@link ContinuationListener#onTimeout(Continuation)}method is called on any {@link ContinuationListener} that has been registered via the{@link #addContinuationListener(ContinuationListener)} method. The onTimeout handlers may write a response and call {@link #complete()}. If {@link #complete()} is not called, then the container will redispatch the request as if {@link #resume()} had been called,except that {@link #isExpired()} will be true and {@link #isResumed()} will be false.
@see ContinuationSupport @see ContinuationListener

        }
        
        final Exchange result = (Exchange) request.getAttribute(EXCHANGE_ATTRIBUTE_NAME);
        if (result == null) {
            // no asynchronous result so leverage continuation
            final Continuation continuation = ContinuationSupport.getContinuation(request);
            if (continuation.isInitial() && continuationTimeout != null) {
                // set timeout on initial
                continuation.setTimeout(continuationTimeout);
            }


            // are we suspended and a request is dispatched initially?
            if (consumer.isSuspended() && continuation.isInitial()) {
                response.sendError(HttpServletResponse.SC_SERVICE_UNAVAILABLE);
                return;
            }


            if (continuation.isExpired()) {
                String id = (String) continuation.getAttribute(EXCHANGE_ATTRIBUTE_ID);
                // remember this id as expired
                expiredExchanges.put(id, id);
                log.warn("Continuation expired of exchangeId: {}", id);
                response.sendError(HttpServletResponse.SC_SERVICE_UNAVAILABLE);
                return;
            }


            // a new request so create an exchange
            final Exchange exchange = new DefaultExchange(consumer.getEndpoint(), ExchangePattern.InOut);


            if (consumer.getEndpoint().isBridgeEndpoint()) {
                exchange.setProperty(Exchange.SKIP_GZIP_ENCODING, Boolean.TRUE);
                exchange.setProperty(Exchange.SKIP_WWW_FORM_URLENCODED, Boolean.TRUE);
            }
            if (consumer.getEndpoint().isDisableStreamCache()) {
                exchange.setProperty(Exchange.DISABLE_HTTP_STREAM_CACHE, Boolean.TRUE);
            }
            
            HttpHelper.setCharsetFromContentType(request.getContentType(), exchange);
            
            exchange.setIn(new HttpMessage(exchange, request, response));
            // set context path as header
            String contextPath = consumer.getEndpoint().getPath();
            exchange.getIn().setHeader("CamelServletContextPath", contextPath);
            
            String httpPath = (String)exchange.getIn().getHeader(Exchange.HTTP_PATH);
            // here we just remove the CamelServletContextPath part from the HTTP_PATH
            if (contextPath != null
                && httpPath.startsWith(contextPath)) {
                exchange.getIn().setHeader(Exchange.HTTP_PATH,
                        httpPath.substring(contextPath.length()));
            }


            if (log.isTraceEnabled()) {
                log.trace("Suspending continuation of exchangeId: {}", exchange.getExchangeId());
            }
            continuation.setAttribute(EXCHANGE_ATTRIBUTE_ID, exchange.getExchangeId());


            // we want to handle the UoW
            try {
                consumer.createUoW(exchange);
            } catch (Exception e) {
                log.error("Error processing request", e);
                throw new ServletException(e);
            }


            // must suspend before we process the exchange
            continuation.suspend();


            ClassLoader oldTccl = overrideTccl(exchange);


            if (log.isTraceEnabled()) {
                log.trace("Processing request for exchangeId: {}", exchange.getExchangeId());
            }
            // use the asynchronous API to process the exchange
            
            consumer.getAsyncProcessor().process(exchange, new AsyncCallback() {
                public void done(boolean doneSync) {
                    // check if the exchange id is already expired
                    boolean expired = expiredExchanges.remove(exchange.getExchangeId()) != null;
                    if (!expired) {
                        if (log.isTraceEnabled()) {
                            log.trace("Resuming continuation of exchangeId: {}", exchange.getExchangeId());
                        }
                        // resume processing after both, sync and async callbacks
                        continuation.setAttribute(EXCHANGE_ATTRIBUTE_NAME, exchange);
                        continuation.resume();
                    } else {
                        log.warn("Cannot resume expired continuation of exchangeId: {}", exchange.getExchangeId());
                    }
                }
            });

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Examples of org.eclipse.jetty.continuation.Continuation

Suspend/Complete Usage

Continuation Timeout

Related Classes of org.eclipse.jetty.continuation.Continuation