/**
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing,
* software distributed under the License is distributed on an
* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
* KIND, either express or implied. See the License for the
* specific language governing permissions and limitations
* under the License.
*/
package org.jooby;
import static java.util.Objects.requireNonNull;
import java.io.IOException;
import java.nio.channels.ClosedChannelException;
import java.nio.charset.StandardCharsets;
import java.util.*;
import java.util.concurrent.Executors;
import java.util.concurrent.ScheduledExecutorService;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.atomic.AtomicReference;
import org.jooby.Route.Chain;
import org.jooby.internal.SseRenderer;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import com.google.common.collect.ImmutableList;
import com.google.common.util.concurrent.MoreExecutors;
import com.google.inject.Injector;
import com.google.inject.Key;
import com.google.inject.TypeLiteral;
import com.google.inject.name.Names;
import javaslang.concurrent.Future;
import javaslang.concurrent.Promise;
import javaslang.control.Try;
import javaslang.control.Try.CheckedRunnable;
/**
* <h1>Server Sent Events</h1>
* <p>
* Server-Sent Events (SSE) is a mechanism that allows server to push the data from the server to
* the client once the client-server connection is established by the client. Once the connection is
* established by the client, it is the server who provides the data and decides to send it to the
* client whenever new <strong>chunk</strong> of data is available.
* </p>
*
* <h2>usage</h2>
*
* <pre>{@code
* {
* sse("/path", sse -> {
* // 1. connected
* sse.send("data"); // 2. send/push data
* });
* }
* }</pre>
*
* <p>
* Simple, effective and easy to use. The callback will be executed once when a new client is
* connected. Inside the callback we can send data, listen for connection close events, etc.
* </p>
*
* <p>
* There is a factory method {@link #event(Object)} that let you set event attributes:
* </p>
*
* <pre>{@code
* {
* sse("/path", sse -> {
* sse.event("data")
* .id("id")
* .name("myevent")
* .retry(5000L)
* .send();
* });
* }
* }</pre>
*
* <h2>structured data</h2>
* <p>
* Beside raw/string data you can also send structured data, like <code>json</code>,
* <code>xml</code>, etc..
* </p>
*
* <p>
* The next example will send two message one in <code>json</code> format and one in
* <code>text/plain</code> format:
* </p>
* :
*
* <pre>{@code
* {
* use(new MyJsonRenderer());
*
* sse("/path", sse -> {
* MyObject object = ...
* sse.send(object, "json");
* sse.send(object, "plain");
* });
* }
* }</pre>
*
* <p>
* Or if your need only one format, just:
* </p>
*
* <pre>{@code
* {
* use(new MyJsonRenderer());
*
* sse("/path", sse -> {
* MyObject object = ...
* sse.send(object);
* }).produces("json"); // by default always send json
* }
* }</pre>
*
* <h2>request params</h2>
* <p>
* We provide request access via two arguments callback:
* </p>
*
* <pre>{@code
* {
* sse("/events/:id", (req, sse) -> {
* String id = req.param("id").value();
* MyObject object = findObject(id);
* sse.send(object);
* });
* }
* }</pre>
*
* <h2>connection lost</h2>
* <p>
* The {@link #onClose(CheckedRunnable)} callback allow you to clean and release resources on
* connection close. A connection is closed by calling {@link #close()} or when the client/browser
* close the connection.
* </p>
*
* <pre>{@code
* {
* sse("/events/:id", sse -> {
* sse.onClose(() -> {
* // clean up resources
* });
* });
* }
* }</pre>
*
* <p>
* The close event will be generated if you try to send an event on a closed connection.
* </p>
*
* <h2>keep alive time</h2>
* <p>
* The keep alive time feature can be used to prevent connections from timing out:
* </p>
*
* <pre>{@code
* {
* sse("/events/:id", sse -> {
* sse.keepAlive(15, TimeUnit.SECONDS);
* });
* }
* }</pre>
*
* <p>
* The previous example will sent a <code>':'</code> message (empty comment) every 15 seconds to
* keep the connection alive. If the client drop the connection, then the
* {@link #onClose(CheckedRunnable)} event will be fired it.
* </p>
*
* <p>
* This feature is useful when you want to detect {@link #onClose(CheckedRunnable)} events without
* waiting for the next time you send a new event. But for example, if your application already
* generate events every 15s, then the use of keep alive is useless and you can avoid it.
* </p>
*
* <h2>require</h2>
* <p>
* The {@link #require(Class)} methods let you access to application services:
* </p>
*
* <pre>{@code
* {
* sse("/events/:id", sse -> {
* MyService service = sse.require(MyService.class);
* });
* }
* }</pre>
*
* <h2>example</h2>
* <p>
* The next example will generate a new event every 60s. It recovers from a server shutdown by using
* the {@link #lastEventId()} and clean resources on connection close.
* </p>
* <pre>{@code
* {
* // creates an executor service
* ScheduledExecutorService executor = Executors.newScheduledThreadPool(1);
*
* sse("/events", sse -> {
* // if we go down, recover from last event ID we sent. Otherwise, start from zero.
* int lastId = sse.lastEventId(Integer.class).orElse(0);
*
* AtomicInteger next = new AtomicInteger(lastId);
*
* // send events every 60s
* ScheduledFuture<?> future = executor.scheduleAtFixedRate(() -> {
* Integer id = next.incrementAndGet();
* Object data = findDataById(id);
*
* // send data and id
* sse.event(data).id(id).send();
* }, 0, 60, TimeUnit.SECONDS);
*
* // on connection lost, cancel 60s task
* sse.onClose(() -> {
* future.cancel(true);
* });
* });
* }
*
* }</pre>
*
* @author edgar
* @since 1.0.0.CR
*/
public abstract class Sse implements AutoCloseable {
/**
* Event representation of Server sent event.
*
* @author edgar
* @since 1.0.0.CR
*/
public static class Event {
private Object id;
private String name;
private Object data;
private Long retry;
private MediaType type;
private String comment;
private Sse sse;
private Event(final Sse sse, final Object data) {
this.sse = sse;
this.data = data;
}
/**
* @return Event data (if any).
*/
public Optional<Object> data() {
return Optional.ofNullable(data);
}
/**
* Event media type helps to render or format event data.
*
* @return Event media type (if any).
*/
public Optional<MediaType> type() {
return Optional.ofNullable(type);
}
/**
* Set event media type. Useful for sengin json, xml, etc..
*
* @param type Media Type.
* @return This event.
*/
public Event type(final MediaType type) {
this.type = requireNonNull(type, "Type is required.");
return this;
}
/**
* Set event media type. Useful for sengin json, xml, etc..
*
* @param type Media Type.
* @return This event.
*/
public Event type(final String type) {
return type(MediaType.valueOf(type));
}
/**
* @return Event id (if any).
*/
public Optional<Object> id() {
return Optional.ofNullable(id);
}
/**
* Set event id.
*
* @param id An event id.
* @return This event.
*/
public Event id(final Object id) {
this.id = requireNonNull(id, "Id is required.");
return this;
}
/**
* @return Event name (a.k.a type).
*/
public Optional<String> name() {
return Optional.ofNullable(name);
}
/**
* Set event name (a.k.a type).
*
* @param name Event's name.
* @return This event.
*/
public Event name(final String name) {
this.name = requireNonNull(name, "Name is required.");
return this;
}
/**
* Clients (browsers) will attempt to reconnect every 3 seconds. The retry option allow you to
* specify the number of millis a browser should wait before try to reconnect.
*
* @param retry Retry value.
* @param unit Time unit.
* @return This event.
*/
public Event retry(final int retry, final TimeUnit unit) {
this.retry = unit.toMillis(retry);
return this;
}
/**
* Clients (browsers) will attempt to reconnect every 3 seconds. The retry option allow you to
* specify the number of millis a browser should wait before try to reconnect.
*
* @param retry Retry value in millis.
* @return This event.
*/
public Event retry(final long retry) {
this.retry = retry;
return this;
}
/**
* @return Event comment (if any).
*/
public Optional<String> comment() {
return Optional.ofNullable(comment);
}
/**
* Set event comment.
*
* @param comment An event comment.
* @return This event.
*/
public Event comment(final String comment) {
this.comment = requireNonNull(comment, "Comment is required.");
return this;
}
/**
* @return Retry event line (if any).
*/
public Optional<Long> retry() {
return Optional.ofNullable(retry);
}
/**
* Send an event and optionally listen for success confirmation or error:
*
* <pre>{@code
* sse.event(data).send().onSuccess(id -> {
* // success
* }).onFailure(cause -> {
* // handle error
* });
* }</pre>
*
* @return A future callback.
*/
public Future<Optional<Object>> send() {
Future<Optional<Object>> future = sse.send(this);
this.id = null;
this.name = null;
this.data = null;
this.type = null;
this.sse = null;
return future;
}
}
/**
* Server-sent event handler.
*
* @author edgar
* @since 1.0.0.CR
*/
public interface Handler extends Route.Filter {
@Override
default void handle(final Request req, final Response rsp, final Chain chain) throws Throwable {
Sse sse = req.require(Sse.class);
String path = req.path();
rsp.send(new Deferred(deferred -> {
try {
sse.handshake(req, () -> {
Try.run(() -> handle(req, sse)).onSuccess(deferred::resolve).onFailure(ex -> {
deferred.reject(ex);
Logger log = LoggerFactory.getLogger(Sse.class);
log.error("execution of {} resulted in error", path, ex);
});
});
} catch (Exception ex) {
deferred.reject(ex);
}
}));
}
/**
* Event handler.
*
* @param req Current request.
* @param sse Sse object.
* @throws Exception If something goes wrong.
*/
void handle(Request req, Sse sse) throws Exception;
}
/**
* Single argument event handler.
*
* @author edgar
* @since 1.0.0.CR
*/
public interface Handler1 extends Handler {
@Override
default void handle(final Request req, final Sse sse) throws Exception {
handle(sse);
}
void handle(Sse sse) throws Exception;
}
/* package */static class KeepAlive implements Runnable {
/** The logging system. */
private final Logger log = LoggerFactory.getLogger(Sse.class);
private Sse sse;
private long retry;
public KeepAlive(final Sse sse, final long retry) {
this.sse = sse;
this.retry = retry;
}
@Override
public void run() {
String sseId = sse.id();
log.debug("running heart beat for {}", sseId);
Try.run(() -> sse.send(Optional.of(sseId), HEART_BEAT).future().onFailure(ex -> {
log.debug("connection lost for {}", sseId);
sse.fireCloseEvent();
Try.run(sse::close);
}).onSuccess(id -> {
log.debug("reschedule heart beat for {}", id);
// reschedule
sse.keepAlive(retry);
}));
}
}
/** Keep alive scheduler. */
private static final ScheduledExecutorService scheduler = Executors
.newSingleThreadScheduledExecutor(r -> {
Thread thread = new Thread(r, "sse-heartbeat");
thread.setDaemon(true);
return thread;
});
/** Empty comment. */
static final byte[] HEART_BEAT = ":\n".getBytes(StandardCharsets.UTF_8);
/** The logging system. */
protected final Logger log = LoggerFactory.getLogger(Sse.class);
private Injector injector;
private List<Renderer> renderers;
private final String id;
private List<MediaType> produces;
private Map<String, Object> locals;
private AtomicReference<CheckedRunnable> onclose = new AtomicReference<>(null);
private Mutant lastEventId;
private boolean closed;
private Locale locale;
public Sse() {
id = UUID.randomUUID().toString();
}
protected void handshake(final Request req, final Runnable handler) throws Exception {
this.injector = req.require(Injector.class);
this.renderers = ImmutableList.copyOf(injector.getInstance(Renderer.KEY));
this.produces = req.route().produces();
this.locals = req.attributes();
this.lastEventId = req.header("Last-Event-ID");
this.locale = req.locale();
handshake(handler);
}
protected abstract void handshake(Runnable handler) throws Exception;
/**
* A unique ID (like a session ID).
*
* @return Sse unique ID (like a session ID).
*/
public String id() {
return id;
}
/**
* Server sent event will send a Last-Event-ID header if the server goes down.
*
* @return Last event id.
*/
public Optional<String> lastEventId() {
return lastEventId(String.class);
}
/**
* Server sent event will send a Last-Event-ID header if the server goes down.
*
* @param type Last event id type.
* @param <T> Event id type.
* @return Last event id.
*/
public <T> Optional<T> lastEventId(final Class<T> type) {
return lastEventId.toOptional(type);
}
/**
* Listen for connection close (usually client drop the connection). This method is useful for
* resources cleanup.
*
* @param task Task to run.
* @return This instance.
*/
public Sse onClose(final CheckedRunnable task) {
onclose.set(task);
return this;
}
/**
* Send an event and set media type.
*
* <pre>{@code
* sse.send(new MyObject(), "json");
* }</pre>
*
* On success the {@link Future#onSuccess(java.util.function.Consumer)} callback will be executed:
*
* <pre>{@code
* sse.send(new MyObject(), "json").onSuccess(id -> {
* //
* });
* }</pre>
*
* The <code>id</code> of the success callback correspond to the {@link Event#id()}.
*
* On error the {@link Future#onFailure(java.util.function.Consumer)} callback will be executed:
*
* <pre>{@code
* sse.send(new MyObject(), "json").onFailure(cause -> {
* //
* });
* }</pre>
*
* @param data Event data.
* @param type Media type, like: json, xml.
* @return A future. The success callback contains the {@link Event#id()}.
*/
public Future<Optional<Object>> send(final Object data, final String type) {
return send(data, MediaType.valueOf(type));
}
/**
* Send an event and set media type.
*
* <pre>{@code
* sse.send(new MyObject(), "json");
* }</pre>
*
* On success the {@link Future#onSuccess(java.util.function.Consumer)} callback will be executed:
*
* <pre>{@code
* sse.send(new MyObject(), "json").onSuccess(id -> {
* //
* });
* }</pre>
*
* The <code>id</code> of the success callback correspond to the {@link Event#id()}.
*
* On error the {@link Future#onFailure(java.util.function.Consumer)} callback will be executed:
*
* <pre>{@code
* sse.send(new MyObject(), "json").onFailure(cause -> {
* //
* });
* }</pre>
*
* @param data Event data.
* @param type Media type, like: json, xml.
* @return A future. The success callback contains the {@link Event#id()}.
*/
public Future<Optional<Object>> send(final Object data, final MediaType type) {
return event(data).type(type).send();
}
/**
* Send an event.
*
* <pre>{@code
* sse.send(new MyObject());
* }</pre>
*
* On success the {@link Future#onSuccess(java.util.function.Consumer)} callback will be executed:
*
* <pre>{@code
* sse.send(new MyObject()).onSuccess(id -> {
* //
* });
* }</pre>
*
* The <code>id</code> of the success callback correspond to the {@link Event#id()}.
*
* On error the {@link Future#onFailure(java.util.function.Consumer)} callback will be executed:
*
* <pre>{@code
* sse.send(new MyObject()).onFailure(cause -> {
* //
* });
* }</pre>
*
* @param data Event data.
* @return A future. The success callback contains the {@link Event#id()}.
*/
public Future<Optional<Object>> send(final Object data) {
return event(data).send();
}
/**
* Factory method for creating {@link Event} instances.
*
* Please note event won't be sent unless you call {@link Event#send()}:
*
* <pre>{@code
* sse.event(new MyObject()).send();
* }</pre>
*
* The factory allow you to set event attributes:
*
* <pre>{@code
* // send data
* MyObject data = ...;
* sse.event(data).send();
*
* // send data with event name
* sse.event(data).name("myevent").send();
*
* // send data with event name and id
* sse.event(data).name("myevent").id(id).send();
*
* // send data with event name, id and retry interval
* sse.event(data).name("myevent").id(id).retry(1500).send();
* }</pre>
*
* @param data Event data.
* @return A new event.
*/
public Event event(final Object data) {
return new Event(this, data);
}
/**
* Ask Guice for the given type.
*
* @param type A service type.
* @param <T> Service type.
* @return A ready to use object.
*/
public <T> T require(final Class<T> type) {
return require(Key.get(type));
}
/**
* Ask Guice for the given type.
*
* @param name A service name.
* @param type A service type.
* @param <T> Service type.
* @return A ready to use object.
*/
public <T> T require(final String name, final Class<T> type) {
return require(Key.get(type, Names.named(name)));
}
/**
* Ask Guice for the given type.
*
* @param type A service type.
* @param <T> Service type.
* @return A ready to use object.
*/
public <T> T require(final TypeLiteral<T> type) {
return require(Key.get(type));
}
/**
* Ask Guice for the given type.
*
* @param key A service key.
* @param <T> Service type.
* @return A ready to use object.
*/
public <T> T require(final Key<T> key) {
return injector.getInstance(key);
}
/**
* The keep alive time can be used to prevent connections from timing out:
*
* <pre>{@code
* {
* sse("/events/:id", sse -> {
* sse.keepAlive(15, TimeUnit.SECONDS);
* });
* }
* }</pre>
*
* <p>
* The previous example will sent a <code>':'</code> message (empty comment) every 15 seconds to
* keep the connection alive. If the client drop the connection, then the
* {@link #onClose(CheckedRunnable)} event will be fired it.
* </p>
*
* <p>
* This feature is useful when you want to detect {@link #onClose(CheckedRunnable)} events without
* waiting until you send a new event. But for example, if your application already generate
* events
* every 15s, then the use of keep alive is useless and you should avoid it.
* </p>
*
* @param time Keep alive time.
* @param unit Time unit.
* @return This instance.
*/
public Sse keepAlive(final int time, final TimeUnit unit) {
return keepAlive(unit.toMillis(time));
}
/**
* The keep alive time can be used to prevent connections from timing out:
*
* <pre>{@code
* {
* sse("/events/:id", sse -> {
* sse.keepAlive(15, TimeUnit.SECONDS);
* });
* }
* }</pre>
*
* <p>
* The previous example will sent a <code>':'</code> message (empty comment) every 15 seconds to
* keep the connection alive. If the client drop the connection, then the
* {@link #onClose(CheckedRunnable)} event will be fired it.
* </p>
*
* <p>
* This feature is useful when you want to detect {@link #onClose(CheckedRunnable)} events without
* waiting until you send a new event. But for example, if your application already generate
* events
* every 15s, then the use of keep alive is useless and you should avoid it.
* </p>
*
* @param millis Keep alive time in millis.
* @return This instance.
*/
public Sse keepAlive(final long millis) {
scheduler.schedule(new KeepAlive(this, millis), millis, TimeUnit.MILLISECONDS);
return this;
}
/**
* Close the connection and fire an {@link #onClose(CheckedRunnable)} event.
*/
@Override
public final void close() throws Exception {
closeAll();
}
private void closeAll() {
synchronized (this) {
if (!closed) {
closed = true;
fireCloseEvent();
closeInternal();
}
}
}
protected abstract void closeInternal();
protected abstract Promise<Optional<Object>> send(Optional<Object> id, byte[] data);
protected void ifClose(final Throwable cause) {
if (shouldClose(cause)) {
closeAll();
}
}
protected void fireCloseEvent() {
CheckedRunnable task = onclose.getAndSet(null);
if (task != null) {
Try.run(task).onFailure(ex -> log.error("close callback resulted in error", ex));
}
}
protected boolean shouldClose(final Throwable ex) {
if (ex instanceof IOException) {
// is there a better way?
boolean brokenPipe = Optional.ofNullable(ex.getMessage())
.map(m -> m.toLowerCase().contains("broken pipe"))
.orElse(false);
return brokenPipe || ex instanceof ClosedChannelException;
}
return false;
}
private Future<Optional<Object>> send(final Event event) {
List<MediaType> produces = event.type().<List<MediaType>> map(ImmutableList::of)
.orElse(this.produces);
SseRenderer ctx = new SseRenderer(renderers, produces, StandardCharsets.UTF_8, locale, locals);
return Try.of(() -> {
byte[] bytes = ctx.format(event);
return send(event.id(), bytes);
}).recover(cause -> {
Promise<Optional<Object>> promise = Promise.make(MoreExecutors.newDirectExecutorService());
promise.failure(cause);
return promise;
}).get().future();
}
}