added implementation of file storage service

java/com.sap.sse.filestorage/META-INF/MANIFEST.MF

@@ -5,3 +5,8 @@ Bundle-SymbolicName: com.sap.sse.filestorage
 Bundle-Version: 1.0.0.qualifier
 Bundle-Vendor: SAP
 Bundle-RequiredExecutionEnvironment: JavaSE-1.8
+Export-Package: com.sap.sse.filestorage,
+ com.sap.sse.filestorage.impl
+Import-Package: org.osgi.framework;version="1.8.0"
+Bundle-Activator: com.sap.sse.filestorage.impl.Activator
+Require-Bundle: org.apache.servicemix.bundles.aws-java-sdk;bundle-version="1.9.8"

java/com.sap.sse.filestorage/src/com/sap/sse/filestorage/FileStorageService.java

@@ -0,0 +1,30 @@
+package com.sap.sse.filestorage;
+
+import java.io.IOException;
+import java.io.InputStream;
+import java.net.URI;
+
+/**
+ * Service for storing files. The interface is intentionally agnostic of the underlying implementation,
+ * which may be provided e.g. by using Amazon's S3 or simply saving the files to a statically reachable
+ * directory on one of our servers.
+ * Implementations of this service are announced via the OSGi service registry.
+ * 
+ * TODO The storage service to use should be configured via the AdminConsole. Upon auto-discovering the
+ * available services, the AdminConsole should allow to edit properties for each service (e.g. access
+ * credentials for AWS S3). We probably need a generic property discovery mechanism (key-value based?),
+ * and to survive server restarts these properties should be saved to the MongoDB.
+ * @author Fredrik Teschke
+ *
+ */
+public interface FileStorageService {
+    /**
+     * @param originalFileName may be {@code null}
+     */
+    URI storeFile(InputStream is, String originalFileName, long lengthInBytes) throws IOException;
+    
+    /**
+     * From the given {@code uri} it should be possible to determine the file to remove.
+     */
+    void removeFile(URI uri);
+}

java/com.sap.sse.filestorage/src/com/sap/sse/filestorage/impl/Activator.java

@@ -0,0 +1,20 @@
+package com.sap.sse.filestorage.impl;
+
+import org.osgi.framework.BundleActivator;
+import org.osgi.framework.BundleContext;
+
+import com.sap.sse.filestorage.FileStorageService;
+
+public class Activator implements BundleActivator {
+
+    @Override
+    public void start(BundleContext context) throws Exception {
+        context.registerService(FileStorageService.class, new AmazonS3FileStorageServiceImpl(), null);        
+    }
+
+    @Override
+    public void stop(BundleContext context) throws Exception {
+
+    }
+
+}

java/com.sap.sse.filestorage/src/com/sap/sse/filestorage/impl/AmazonS3FileStorageServiceImpl.java

@@ -0,0 +1,96 @@
+package com.sap.sse.filestorage.impl;
+
+import java.io.InputStream;
+import java.net.URI;
+import java.net.URISyntaxException;
+import java.util.UUID;
+import java.util.logging.Level;
+import java.util.logging.Logger;
+
+import com.amazonaws.AmazonClientException;
+import com.amazonaws.auth.AWSCredentials;
+import com.amazonaws.auth.profile.ProfileCredentialsProvider;
+import com.amazonaws.services.s3.AmazonS3;
+import com.amazonaws.services.s3.AmazonS3Client;
+import com.amazonaws.services.s3.model.CannedAccessControlList;
+import com.amazonaws.services.s3.model.DeleteObjectRequest;
+import com.amazonaws.services.s3.model.ObjectMetadata;
+import com.amazonaws.services.s3.model.PutObjectRequest;
+import com.sap.sse.filestorage.FileStorageService;
+
+/**
+ * For testing purposes configure the access credentials as follows:
+ * To link this service to an AWS account, create the following file: ~/.aws/credentials
+ * and add credentials to it (get the access id and secret key from
+ * https://console.aws.amazon.com/iam/home?#security_credential).
+ * 
+ * TODO configure credentials in AdminConsole
+ * TODO configure bucket name in AdminConsole
+ * 
+ * @author Fredrik Teschke
+ *
+ */
+public class AmazonS3FileStorageServiceImpl implements FileStorageService {
+    private static final Logger logger = Logger.getLogger(AmazonS3FileStorageServiceImpl.class.getName());
+    
+    private static final String baseUrl = "s3.amazonaws.com";
+    private static final String retrievalProtocol = "http";
+    private static final String bucketName = "ftes-sap-sailing";
+    private final AmazonS3 s3;
+    
+    public AmazonS3FileStorageServiceImpl() {
+        /*
+         * The ProfileCredentialsProvider will return your [default]
+         * credential profile by reading from the credentials file located at
+         * (~/.aws/credentials).
+         */
+        AWSCredentials credentials = null;
+        try {
+            credentials = new ProfileCredentialsProvider().getCredentials();
+        } catch (Exception e) {
+            throw new AmazonClientException(
+                    "Cannot load the credentials from the credential profiles file. " +
+                    "Please make sure that your credentials file is at the correct " +
+                    "location (~/.aws/credentials), and is in valid format.",
+                    e);
+        }
+
+        s3 = new AmazonS3Client(credentials);
+    }
+    
+    private static String getKey(String originalFileName) {
+        String key = UUID.randomUUID().toString();
+        if (originalFileName != null) {
+            key += "/" + originalFileName;
+        }
+        return key;
+    }
+    
+    private static URI getUri(String key) {
+        try {
+            return new URI(retrievalProtocol, bucketName + "." + baseUrl, key, null);
+        } catch (URISyntaxException e) {
+            logger.log(Level.WARNING, "Could not create URI for uploaded file with key " + key, e);
+            return null;
+        }
+    }
+
+
+    @Override
+    public URI storeFile(InputStream is, String originalFileName, long lengthInBytes) {
+        ObjectMetadata metadata = new ObjectMetadata();
+        metadata.setContentLength(lengthInBytes);
+        String key = getKey(originalFileName);
+        PutObjectRequest request = new PutObjectRequest(bucketName, key, is, metadata)
+            .withCannedAcl(CannedAccessControlList.PublicRead);
+        s3.putObject(request);
+        return getUri(key);
+    }
+
+    @Override
+    public void removeFile(URI uri) {
+        String key = uri.getPath();
+        s3.deleteObject(new DeleteObjectRequest(bucketName, key));
+    }
+
+}