Introduction of an AudioServlet to provide audio streams through HTTP (…

…#2287)

* Introduction of an AudioServlet to provide audio streams through HTTP

Signed-off-by: Kai Kreuzer <kai@openhab.org>

* fixed missing stream removal

Signed-off-by: Kai Kreuzer <kai@openhab.org>

bundles/core/org.eclipse.smarthome.core.audio/META-INF/MANIFEST.MF

@@ -6,7 +6,9 @@ Bundle-Version: 0.9.0.qualifier
 Bundle-Vendor: Eclipse.org/SmartHome
 Bundle-RequiredExecutionEnvironment: JavaSE-1.7
 Bundle-ClassPath: .
-Import-Package: org.apache.commons.io,
+Import-Package: javax.servlet,
+ javax.servlet.http,
+ org.apache.commons.io,
  org.apache.commons.lang,
  org.eclipse.smarthome.config.core,
  org.eclipse.smarthome.core.audio,
@@ -20,6 +22,7 @@ Import-Package: org.apache.commons.io,
  org.eclipse.smarthome.io.console,
  org.eclipse.smarthome.io.console.extensions,
  org.osgi.framework,
+ org.osgi.service.http,
  org.slf4j
 Export-Package: org.eclipse.smarthome.core.audio
 Service-Component: OSGI-INF/*.xml

bundles/core/org.eclipse.smarthome.core.audio/OSGI-INF/AudioServlet.xml

@@ -0,0 +1,21 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!--
+
+ Copyright (c) 2014-2016 by the respective copyright holders.
+ All rights reserved. This program and the accompanying materials
+ are made available under the terms of the Eclipse Public License v1.0
+ which accompanies this distribution, and is available at
+ http://www.eclipse.org/legal/epl-v10.html
+
+-->
+<scr:component xmlns:scr="http://www.osgi.org/xmlns/scr/v1.1.0"
+ name="org.eclipse.smarthome.core.audio.audioservlet">
+ <implementation
+ class="org.eclipse.smarthome.core.audio.internal.AudioServlet" />
+ <reference interface="org.osgi.service.http.HttpService"
+ cardinality="1..1" policy="static" name="HttpService" bind="setHttpService"
+ unbind="unsetHttpService" />
+ <service>
+ <provide interface="org.eclipse.smarthome.core.audio.AudioHTTPServer"/>
+ </service>
+</scr:component>

bundles/core/org.eclipse.smarthome.core.audio/src/main/java/org/eclipse/smarthome/core/audio/AudioHTTPServer.java

@@ -0,0 +1,43 @@
+/**
+ * Copyright (c) 2014-2016 by the respective copyright holders.
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the Eclipse Public License v1.0
+ * which accompanies this distribution, and is available at
+ * http://www.eclipse.org/legal/epl-v10.html
+ */
+package org.eclipse.smarthome.core.audio;
+
+import java.net.URL;
+
+import org.eclipse.smarthome.core.audio.internal.AudioServlet;
+
+/**
+ * This is an interface that is implemented by {@link AudioServlet} and which allows exposing audio streams through
+ * HTTP.
+ * Streams are only served a single time and then discarded.
+ *
+ * @author Kai Kreuzer - Initial contribution and API
+ *
+ */
+public interface AudioHTTPServer {
+
+ /**
+ * Creates a url for a given {@link AudioStream} where it can be requested a single time.
+ *
+ * @param stream the stream to serve on HTTP
+ * @return the absolute URL to access the stream (using the primary network interface)
+ */
+ URL serve(AudioStream stream);
+
+ /**
+ * Creates a url for a given {@link AudioStream} where it can be requested a single time.
+ * This method makes sure that the HTTP response contains the "Content-Length" header as some clients require this.
+ * Note that this should only be used if really needed, since it might mean that the whole stream has to be read
+ * locally first in order to determine its length.
+ *
+ * @param stream the stream to serve on HTTP
+ * @return the absolute URL to access the stream (using the primary network interface)
+ */
+ URL serveWithSize(AudioStream stream);
+
+}

bundles/core/org.eclipse.smarthome.core.audio/src/main/java/org/eclipse/smarthome/core/audio/internal/AudioServlet.java

@@ -0,0 +1,229 @@
+/**
+ * Copyright (c) 2014-2016 by the respective copyright holders.
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the Eclipse Public License v1.0
+ * which accompanies this distribution, and is available at
+ * http://www.eclipse.org/legal/epl-v10.html
+ */
+package org.eclipse.smarthome.core.audio.internal;
+
+import java.io.IOException;
+import java.net.InetAddress;
+import java.net.MalformedURLException;
+import java.net.URL;
+import java.net.UnknownHostException;
+import java.util.Hashtable;
+import java.util.Map;
+import java.util.UUID;
+import java.util.concurrent.ConcurrentHashMap;
+
+import javax.servlet.ServletException;
+import javax.servlet.ServletOutputStream;
+import javax.servlet.http.HttpServlet;
+import javax.servlet.http.HttpServletRequest;
+import javax.servlet.http.HttpServletResponse;
+
+import org.apache.commons.io.IOUtils;
+import org.apache.commons.lang.StringUtils;
+import org.eclipse.smarthome.core.audio.AudioFormat;
+import org.eclipse.smarthome.core.audio.AudioHTTPServer;
+import org.eclipse.smarthome.core.audio.AudioStream;
+import org.osgi.framework.BundleContext;
+import org.osgi.service.http.HttpContext;
+import org.osgi.service.http.HttpService;
+import org.osgi.service.http.NamespaceException;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+/**
+ * A servlet that serves audio streams via HTTP.
+ *
+ * @author Kai Kreuzer - Initial contribution and API
+ *
+ */
+public class AudioServlet extends HttpServlet implements AudioHTTPServer {
+
+ private static final long serialVersionUID = -3364664035854567854L;
+
+ private static final String SERVLET_NAME = "/audio";
+
+ private final Logger logger = LoggerFactory.getLogger(AudioServlet.class);
+
+ private Map<String, AudioStream> streams = new ConcurrentHashMap<>();
+
+ protected HttpService httpService;
+ private BundleContext bundleContext;
+
+ protected void activate(BundleContext bundleContext) {
+ this.bundleContext = bundleContext;
+ }
+
+ protected void deactivate(BundleContext bundleContext) {
+ this.bundleContext = null;
+ }
+
+ protected void setHttpService(HttpService httpService) {
+ this.httpService = httpService;
+
+ try {
+ logger.debug("Starting up the audio servlet at " + SERVLET_NAME);
+ Hashtable<String, String> props = new Hashtable<String, String>();
+ httpService.registerServlet(SERVLET_NAME, this, props, createHttpContext());
+ } catch (NamespaceException e) {
+ logger.error("Error during servlet startup", e);
+ } catch (ServletException e) {
+ logger.error("Error during servlet startup", e);
+ }
+ }
+
+ protected void unsetHttpService(HttpService httpService) {
+ httpService.unregister(SERVLET_NAME);
+ this.httpService = null;
+ }
+
+ /**
+ * Creates an {@link HttpContext}.
+ *
+ * @return an {@link HttpContext} that grants anonymous access
+ */
+ protected HttpContext createHttpContext() {
+ // TODO: Once we have a role-based permission system in place, we need to make sure that we create an
+ // HttpContext here, which allows accessing the servlet without any authentication.
+ HttpContext httpContext = httpService.createDefaultHttpContext();
+ return httpContext;
+ }
+
+ @Override
+ protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
+ String streamId = StringUtils.substringAfterLast(req.getRequestURI(), "/");
+ if (!streams.containsKey(streamId)) {
+ logger.debug("Received request for invalid stream id at {}", req.getRequestURI());
+ resp.sendError(HttpServletResponse.SC_NOT_FOUND);
+ } else {
+ logger.debug("Stream to serve is {}", streamId);
+
+ AudioStream stream = streams.remove(streamId);
+
+ // try to set the content-type, if possible
+ String mimeType = null;
+ if (stream.getFormat().getCodec() == AudioFormat.CODEC_MP3) {
+ mimeType = "audio/mpeg";
+ } else if (stream.getFormat().getContainer() == AudioFormat.CONTAINER_WAVE) {
+ mimeType = "audio/wav";
+ } else if (stream.getFormat().getContainer() == AudioFormat.CONTAINER_OGG) {
+ mimeType = "audio/ogg";
+ }
+ if (mimeType != null) {
+ resp.setContentType(mimeType);
+ }
+
+ // try to set the content-length, if possible
+ if (stream instanceof DiscreteAudioStream) {
+ Integer size = ((DiscreteAudioStream) stream).size();
+ if (size != null) {
+ resp.setContentLength(size);
+ }
+ }
+
+ ServletOutputStream os = resp.getOutputStream();
+ IOUtils.copy(stream, os);
+ resp.flushBuffer();
+ IOUtils.closeQuietly(stream);
+ }
+ }
+
+ @Override
+ public URL serve(AudioStream stream) {
+ String streamId = UUID.randomUUID().toString();
+ streams.put(streamId, stream);
+ return getURL(streamId);
+ }
+
+ @Override
+ public URL serveWithSize(AudioStream stream) {
+ if (stream.markSupported()) {
+ DiscreteAudioStream streamWithSize = new DiscreteAudioStream(stream);
+ return serve(streamWithSize);
+ } else {
+ // TODO: We should also support streams without mark support, but this will mean that we have to read it
+ // first to memory or file system and create a new AudioStream from there.
+ logger.warn("Stream cannot be reset, so it is served without size through HTTP");
+ return serve(stream);
+ }
+ }
+
+ private URL getURL(String streamId) {
+ try {
+ String ipAddress = InetAddress.getLocalHost().getHostAddress(); // we use the primary interface; if a client
+ // knows it any better, he can himself
+ // change the url according to his needs.
+ String port = bundleContext.getProperty("org.osgi.service.http.port"); // we do not use SSL as it can cause
+ // certificate validation issues.
+ return new URL("http://" + ipAddress + ":" + port + SERVLET_NAME + "/" + streamId);
+ } catch (UnknownHostException | MalformedURLException e) {
+ logger.error("Failed to construct audio stream URL: {}", e.getMessage(), e);
+ return null;
+ }
+ }
+
+ /**
+ * This is a wrapper class around {@link AudioStream}, which additionally provides information about its size.
+ * Currently, it only support mark-supporting AudioStreams, which are read and reset in order to dertermine the
+ * stream size.
+ */
+ class DiscreteAudioStream extends AudioStream {
+
+ private Integer size;
+ private AudioStream stream;
+
+ public DiscreteAudioStream(AudioStream stream) {
+ this.stream = stream;
+ }
+
+ public Integer size() {
+ if (size == null) {
+ size = calculateSize();
+ }
+ return size;
+ }
+
+ private Integer calculateSize() {
+ if (stream.markSupported()) {
+ return readStreamAndReset(stream);
+ }
+ return null;
+ }
+
+ private Integer readStreamAndReset(AudioStream s) {
+ int bytes = 0;
+ int avail = 0;
+ try {
+ while ((avail = s.available()) > 0) {
+ bytes += avail;
+ s.skip(avail);
+ }
+ s.reset();
+ } catch (IOException e) {
+ logger.warn("Cannot determine size of audio stream!", e);
+ return null;
+ }
+ return bytes;
+ }
+
+ @Override
+ public AudioFormat getFormat() {
+ return stream.getFormat();
+ }
+
+ @Override
+ public int read() throws IOException {
+ return stream.read();
+ }
+
+ @Override
+ public void close() throws IOException {
+ stream.close();
+ }
+
+ }
+}