Azure Functions Java Worker: Complete Implementation Guide

Azure Functions Java Worker enables running Java functions in Azure Functions runtime. This guide covers creating, deploying, and managing Java functions with Azure Functions.

Setup and Dependencies

1. Maven Configuration

<project> <modelVersion>4.0.0</modelVersion> <groupId>com.company.azure.functions</groupId> <artifactId>azure-java-functions</artifactId> <version>1.0.0</version> <packaging>jar</packaging> <properties> <maven.compiler.source>11</maven.compiler.source> <maven.compiler.target>11</maven.compiler.target> <functionAppName>java-functions-app</functionAppName> <functionAppRegion>eastus</functionAppRegion> <stagingDirectory>${project.build.directory}/azure-functions/${functionAppName}</stagingDirectory> <azure.functions.maven.plugin.version>1.26.0</azure.functions.maven.plugin.version> <azure.functions.java.library.version>3.0.0</azure.functions.java.library.version> </properties> <dependencies> <!-- Azure Functions Java Library --> <dependency> <groupId>com.microsoft.azure.functions</groupId> <artifactId>azure-functions-java-library</artifactId> <version>${azure.functions.java.library.version}</version> </dependency> <!-- Azure Storage SDK for Blob, Queue, Table bindings --> <dependency> <groupId>com.azure</groupId> <artifactId>azure-storage-blob</artifactId> <version>12.20.0</version> </dependency> <dependency> <groupId>com.azure</groupId> <artifactId>azure-storage-queue</artifactId> <version>12.16.0</version> </dependency> <!-- JSON Processing --> <dependency> <groupId>com.fasterxml.jackson.core</groupId> <artifactId>jackson-databind</artifactId> <version>2.15.2</version> </dependency> <!-- HTTP Client --> <dependency> <groupId>com.squareup.okhttp3</groupId> <artifactId>okhttp</artifactId> <version>4.11.0</version> </dependency> <!-- Logging --> <dependency> <groupId>org.slf4j</groupId> <artifactId>slf4j-simple</artifactId> <version>2.0.7</version> </dependency> <!-- Testing --> <dependency> <groupId>org.junit.jupiter</groupId> <artifactId>junit-jupiter</artifactId> <version>5.9.3</version> <scope>test</scope> </dependency> <dependency> <groupId>com.microsoft.azure.functions</groupId> <artifactId>azure-functions-java-library-test</artifactId> <version>1.0.0</version> <scope>test</scope> </dependency> </dependencies> <build> <plugins> <plugin> <groupId>com.microsoft.azure</groupId> <artifactId>azure-functions-maven-plugin</artifactId> <version>${azure.functions.maven.plugin.version}</version> <configuration> <appName>${functionAppName}</appName> <resourceGroup>java-functions-rg</resourceGroup> <appServicePlanName>java-functions-asp</appServicePlanName> <region>${functionAppRegion}</region> <runtime> <os>windows</os> <javaVersion>11</javaVersion> </runtime> <appSettings> <property> <name>FUNCTIONS_EXTENSION_VERSION</name> <value>~4</value> </property> <property> <name>FUNCTIONS_WORKER_RUNTIME</name> <value>java</value> </property> </appSettings> </configuration> <executions> <execution> <id>package-functions</id> <goals> <goal>package</goal> </goals> </execution> </executions> </plugin> <plugin> <groupId>org.apache.maven.plugins</groupId> <artifactId>maven-compiler-plugin</artifactId> <version>3.11.0</version> <configuration> <source>11</source> <target>11</target> <encoding>UTF-8</encoding> </configuration> </plugin> <plugin> <groupId>org.apache.maven.plugins</groupId> <artifactId>maven-surefire-plugin</artifactId> <version>3.0.0</version> </plugin> </plugins> </build> </project>

2. Host Configuration

{ "version": "2.0", "extensionBundle": { "id": "Microsoft.Azure.Functions.ExtensionBundle", "version": "[2.*, 3.0.0)" }, "extensions": { "http": { "routePrefix": "api", "maxOutstandingRequests": 200, "maxConcurrentRequests": 100, "dynamicThrottlesEnabled": true }, "queues": { "batchSize": 16, "newBatchThreshold": 8, "maxDequeueCount": 5, "maxPollingInterval": "00:00:02" }, "serviceBus": { "prefetchCount": 100, "messageHandlerOptions": { "autoComplete": true, "maxConcurrentCalls": 32, "maxAutoRenewDuration": "00:05:00" } } }, "logging": { "fileLoggingMode": "debugOnly", "logLevel": { "default": "Information", "Host.Results": "Error", "Function": "Information", "Host.Aggregator": "Trace" }, "applicationInsights": { "samplingSettings": { "isEnabled": true, "maxTelemetryItemsPerSecond": 5 } } }, "functionTimeout": "00:10:00", "healthMonitor": { "enabled": true, "healthCheckInterval": "00:00:10", "healthCheckWindow": "00:02:00", "healthCheckThreshold": 6, "counterThreshold": 0.80 } }

Core Function Implementations

1. HTTP Trigger Functions

package com.company.azure.functions; import com.microsoft.azure.functions.*; import com.microsoft.azure.functions.annotation.*; import com.fasterxml.jackson.databind.ObjectMapper; import java.io.IOException; import java.util.*; import java.util.concurrent.ConcurrentHashMap; import java.util.logging.Level; import java.util.logging.Logger; /** * HTTP Trigger Functions for User Management */ public class UserFunctions { private static final Logger LOGGER = Logger.getLogger(UserFunctions.class.getName()); private static final ObjectMapper OBJECT_MAPPER = new ObjectMapper(); private static final Map<String, User> USER_STORE = new ConcurrentHashMap<>(); private static final Random RANDOM = new Random(); /** * HTTP POST - Create User */ @FunctionName("createUser") public HttpResponseMessage createUser( @HttpTrigger( name = "req", methods = {HttpMethod.POST}, authLevel = AuthorizationLevel.FUNCTION, route = "users" ) HttpRequestMessage<Optional<String>> request, final ExecutionContext context) { context.getLogger().info("Java HTTP trigger processed a request to create user."); try { // Parse request body String requestBody = request.getBody().orElseThrow(() -> new IllegalArgumentException("Request body is required")); UserCreateRequest createRequest = OBJECT_MAPPER.readValue(requestBody, UserCreateRequest.class); // Validate input if (createRequest.getEmail() == null || createRequest.getEmail().trim().isEmpty()) { return request.createResponseBuilder(HttpStatus.BAD_REQUEST) .body("{\"error\": \"Email is required\"}") .header("Content-Type", "application/json") .build(); } // Check for duplicate email boolean emailExists = USER_STORE.values().stream() .anyMatch(user -> user.getEmail().equalsIgnoreCase(createRequest.getEmail())); if (emailExists) { return request.createResponseBuilder(HttpStatus.CONFLICT) .body("{\"error\": \"User with this email already exists\"}") .header("Content-Type", "application/json") .build(); } // Create user String userId = "user-" + System.currentTimeMillis() + "-" + RANDOM.nextInt(1000); User user = new User( userId, createRequest.getEmail(), createRequest.getFirstName(), createRequest.getLastName(), System.currentTimeMillis() ); USER_STORE.put(userId, user); // Log success context.getLogger().info("User created successfully: " + userId); // Return response UserResponse response = new UserResponse( "User created successfully", user ); return request.createResponseBuilder(HttpStatus.CREATED) .body(OBJECT_MAPPER.writeValueAsString(response)) .header("Content-Type", "application/json") .build(); } catch (IOException e) { context.getLogger().severe("Error parsing request body: " + e.getMessage()); return request.createResponseBuilder(HttpStatus.BAD_REQUEST) .body("{\"error\": \"Invalid JSON format\"}") .header("Content-Type", "application/json") .build(); } catch (Exception e) { context.getLogger().severe("Error creating user: " + e.getMessage()); return request.createResponseBuilder(HttpStatus.INTERNAL_SERVER_ERROR) .body("{\"error\": \"Internal server error\"}") .header("Content-Type", "application/json") .build(); } } /** * HTTP GET - Get User by ID */ @FunctionName("getUser") public HttpResponseMessage getUser( @HttpTrigger( name = "req", methods = {HttpMethod.GET}, authLevel = AuthorizationLevel.FUNCTION, route = "users/{id}" ) HttpRequestMessage<Optional<String>> request, @BindingName("id") String userId, final ExecutionContext context) { context.getLogger().info("Java HTTP trigger processed a request to get user: " + userId); try { User user = USER_STORE.get(userId); if (user == null) { return request.createResponseBuilder(HttpStatus.NOT_FOUND) .body("{\"error\": \"User not found\"}") .header("Content-Type", "application/json") .build(); } UserResponse response = new UserResponse( "User retrieved successfully", user ); return request.createResponseBuilder(HttpStatus.OK) .body(OBJECT_MAPPER.writeValueAsString(response)) .header("Content-Type", "application/json") .build(); } catch (Exception e) { context.getLogger().severe("Error retrieving user: " + e.getMessage()); return request.createResponseBuilder(HttpStatus.INTERNAL_SERVER_ERROR) .body("{\"error\": \"Internal server error\"}") .header("Content-Type", "application/json") .build(); } } /** * HTTP GET - List All Users */ @FunctionName("listUsers") public HttpResponseMessage listUsers( @HttpTrigger( name = "req", methods = {HttpMethod.GET}, authLevel = AuthorizationLevel.FUNCTION, route = "users" ) HttpRequestMessage<Optional<String>> request, final ExecutionContext context) { context.getLogger().info("Java HTTP trigger processed a request to list users."); try { List<User> users = new ArrayList<>(USER_STORE.values()); UserListResponse response = new UserListResponse( "Users retrieved successfully", users.size(), users ); return request.createResponseBuilder(HttpStatus.OK) .body(OBJECT_MAPPER.writeValueAsString(response)) .header("Content-Type", "application/json") .build(); } catch (Exception e) { context.getLogger().severe("Error listing users: " + e.getMessage()); return request.createResponseBuilder(HttpStatus.INTERNAL_SERVER_ERROR) .body("{\"error\": \"Internal server error\"}") .header("Content-Type", "application/json") .build(); } } /** * HTTP PUT - Update User */ @FunctionName("updateUser") public HttpResponseMessage updateUser( @HttpTrigger( name = "req", methods = {HttpMethod.PUT}, authLevel = AuthorizationLevel.FUNCTION, route = "users/{id}" ) HttpRequestMessage<Optional<String>> request, @BindingName("id") String userId, final ExecutionContext context) { context.getLogger().info("Java HTTP trigger processed a request to update user: " + userId); try { User existingUser = USER_STORE.get(userId); if (existingUser == null) { return request.createResponseBuilder(HttpStatus.NOT_FOUND) .body("{\"error\": \"User not found\"}") .header("Content-Type", "application/json") .build(); } String requestBody = request.getBody().orElseThrow(() -> new IllegalArgumentException("Request body is required")); UserUpdateRequest updateRequest = OBJECT_MAPPER.readValue(requestBody, UserUpdateRequest.class); // Update user User updatedUser = new User( existingUser.getId(), existingUser.getEmail(), // Email cannot be changed updateRequest.getFirstName() != null ? updateRequest.getFirstName() : existingUser.getFirstName(), updateRequest.getLastName() != null ? updateRequest.getLastName() : existingUser.getLastName(), existingUser.getCreatedAt() ); USER_STORE.put(userId, updatedUser); UserResponse response = new UserResponse( "User updated successfully", updatedUser ); return request.createResponseBuilder(HttpStatus.OK) .body(OBJECT_MAPPER.writeValueAsString(response)) .header("Content-Type", "application/json") .build(); } catch (IOException e) { context.getLogger().severe("Error parsing request body: " + e.getMessage()); return request.createResponseBuilder(HttpStatus.BAD_REQUEST) .body("{\"error\": \"Invalid JSON format\"}") .header("Content-Type", "application/json") .build(); } catch (Exception e) { context.getLogger().severe("Error updating user: " + e.getMessage()); return request.createResponseBuilder(HttpStatus.INTERNAL_SERVER_ERROR) .body("{\"error\": \"Internal server error\"}") .header("Content-Type", "application/json") .build(); } } /** * HTTP DELETE - Delete User */ @FunctionName("deleteUser") public HttpResponseMessage deleteUser( @HttpTrigger( name = "req", methods = {HttpMethod.DELETE}, authLevel = AuthorizationLevel.FUNCTION, route = "users/{id}" ) HttpRequestMessage<Optional<String>> request, @BindingName("id") String userId, final ExecutionContext context) { context.getLogger().info("Java HTTP trigger processed a request to delete user: " + userId); try { User removedUser = USER_STORE.remove(userId); if (removedUser == null) { return request.createResponseBuilder(HttpStatus.NOT_FOUND) .body("{\"error\": \"User not found\"}") .header("Content-Type", "application/json") .build(); } DeleteResponse response = new DeleteResponse( "User deleted successfully", userId, System.currentTimeMillis() ); return request.createResponseBuilder(HttpStatus.OK) .body(OBJECT_MAPPER.writeValueAsString(response)) .header("Content-Type", "application/json") .build(); } catch (Exception e) { context.getLogger().severe("Error deleting user: " + e.getMessage()); return request.createResponseBuilder(HttpStatus.INTERNAL_SERVER_ERROR) .body("{\"error\": \"Internal server error\"}") .header("Content-Type", "application/json") .build(); } } // Data Models public static class UserCreateRequest { private String email; private String firstName; private String lastName; // Getters and setters public String getEmail() { return email; } public void setEmail(String email) { this.email = email; } public String getFirstName() { return firstName; } public void setFirstName(String firstName) { this.firstName = firstName; } public String getLastName() { return lastName; } public void setLastName(String lastName) { this.lastName = lastName; } } public static class UserUpdateRequest { private String firstName; private String lastName; // Getters and setters public String getFirstName() { return firstName; } public void setFirstName(String firstName) { this.firstName = firstName; } public String getLastName() { return lastName; } public void setLastName(String lastName) { this.lastName = lastName; } } public static class User { private final String id; private final String email; private final String firstName; private final String lastName; private final long createdAt; public User(String id, String email, String firstName, String lastName, long createdAt) { this.id = id; this.email = email; this.firstName = firstName; this.lastName = lastName; this.createdAt = createdAt; } // Getters public String getId() { return id; } public String getEmail() { return email; } public String getFirstName() { return firstName; } public String getLastName() { return lastName; } public long getCreatedAt() { return createdAt; } } public static class UserResponse { private final String message; private final User user; public UserResponse(String message, User user) { this.message = message; this.user = user; } // Getters public String getMessage() { return message; } public User getUser() { return user; } } public static class UserListResponse { private final String message; private final int total; private final List<User> users; public UserListResponse(String message, int total, List<User> users) { this.message = message; this.total = total; this.users = users; } // Getters public String getMessage() { return message; } public int getTotal() { return total; } public List<User> getUsers() { return users; } } public static class DeleteResponse { private final String message; private final String userId; private final long deletedAt; public DeleteResponse(String message, String userId, long deletedAt) { this.message = message; this.userId = userId; this.deletedAt = deletedAt; } // Getters public String getMessage() { return message; } public String getUserId() { return userId; } public long getDeletedAt() { return deletedAt; } } }

2. Blob Storage Trigger Functions

package com.company.azure.functions; import com.microsoft.azure.functions.*; import com.microsoft.azure.functions.annotation.*; import com.azure.storage.blob.BlobClient; import com.azure.storage.blob.BlobContainerClient; import com.azure.storage.blob.BlobServiceClient; import com.azure.storage.blob.BlobServiceClientBuilder; import com.fasterxml.jackson.databind.ObjectMapper; import java.io.ByteArrayInputStream; import java.io.IOException; import java.nio.charset.StandardCharsets; import java.util.logging.Logger; /** * Blob Storage Trigger Functions */ public class BlobStorageFunctions { private static final Logger LOGGER = Logger.getLogger(BlobStorageFunctions.class.getName()); private static final ObjectMapper OBJECT_MAPPER = new ObjectMapper(); private static BlobServiceClient blobServiceClient; static { // Initialize Blob Service Client String connectionString = System.getenv("AzureWebJobsStorage"); blobServiceClient = new BlobServiceClientBuilder() .connectionString(connectionString) .buildClient(); } /** * Blob Trigger - Process new user data files */ @FunctionName("processUserDataBlob") public void processUserDataBlob( @BlobTrigger( name = "content", path = "user-data/{name}", dataType = "binary", connection = "AzureWebJobsStorage" ) byte[] content, @BindingName("name") String filename, final ExecutionContext context) { context.getLogger().info("Java Blob trigger function processed a blob: " + filename); try { String fileContent = new String(content, StandardCharsets.UTF_8); context.getLogger().info("Blob content: " + fileContent); // Process the blob content UserBatchData batchData = OBJECT_MAPPER.readValue(fileContent, UserBatchData.class); context.getLogger().info(String.format( "Processing batch data with %d users", batchData.getUsers().size())); // Process each user in the batch for (UserBatchData.UserData userData : batchData.getUsers()) { processUserData(userData, context); } // Move processed blob to archive container moveBlobToArchive(filename, content, context); context.getLogger().info("Successfully processed blob: " + filename); } catch (Exception e) { context.getLogger().severe("Error processing blob " + filename + ": " + e.getMessage()); // Move failed blob to error container moveBlobToError(filename, content, context); } } /** * Blob Output - Generate user report */ @FunctionName("generateUserReport") public HttpResponseMessage generateUserReport( @HttpTrigger( name = "req", methods = {HttpMethod.GET}, authLevel = AuthorizationLevel.FUNCTION, route = "reports/users" ) HttpRequestMessage<Optional<String>> request, @BlobOutput( name = "report", path = "reports/user-report-{datetime}.json", connection = "AzureWebJobsStorage" ) OutputBinding<String> reportOutput, final ExecutionContext context) { context.getLogger().info("Java HTTP trigger function processed a request to generate user report."); try { // Generate report data UserReport report = generateUserReportData(); String reportJson = OBJECT_MAPPER.writeValueAsString(report); // Set output blob content reportOutput.setValue(reportJson); return request.createResponseBuilder(HttpStatus.OK) .body("{\"message\": \"User report generated successfully\", \"reportPath\": \"reports/user-report-\" + System.currentTimeMillis() + \".json\"}") .header("Content-Type", "application/json") .build(); } catch (Exception e) { context.getLogger().severe("Error generating user report: " + e.getMessage()); return request.createResponseBuilder(HttpStatus.INTERNAL_SERVER_ERROR) .body("{\"error\": \"Failed to generate report\"}") .header("Content-Type", "application/json") .build(); } } private void processUserData(UserBatchData.UserData userData, ExecutionContext context) { context.getLogger().info("Processing user: " + userData.getEmail()); // Implement user processing logic // This could include validation, transformation, storage, etc. try { Thread.sleep(100); // Simulate processing time context.getLogger().info("Successfully processed user: " + userData.getEmail()); } catch (InterruptedException e) { Thread.currentThread().interrupt(); context.getLogger().warning("User processing interrupted: " + userData.getEmail()); } } private void moveBlobToArchive(String filename, byte[] content, ExecutionContext context) { try { BlobContainerClient archiveContainer = blobServiceClient.getBlobContainerClient("user-data-archive"); if (!archiveContainer.exists()) { archiveContainer.create(); } BlobClient archiveBlob = archiveContainer.getBlobClient(filename); archiveBlob.upload(new ByteArrayInputStream(content), content.length, true); // Delete from original container BlobContainerClient sourceContainer = blobServiceClient.getBlobContainerClient("user-data"); BlobClient sourceBlob = sourceContainer.getBlobClient(filename); sourceBlob.delete(); context.getLogger().info("Moved blob to archive: " + filename); } catch (Exception e) { context.getLogger().severe("Error moving blob to archive: " + e.getMessage()); } } private void moveBlobToError(String filename, byte[] content, ExecutionContext context) { try { BlobContainerClient errorContainer = blobServiceClient.getBlobContainerClient("user-data-errors"); if (!errorContainer.exists()) { errorContainer.create(); } BlobClient errorBlob = errorContainer.getBlobClient(filename); errorBlob.upload(new ByteArrayInputStream(content), content.length, true); // Delete from original container BlobContainerClient sourceContainer = blobServiceClient.getBlobContainerClient("user-data"); BlobClient sourceBlob = sourceContainer.getBlobClient(filename); sourceBlob.delete(); context.getLogger().info("Moved blob to error container: " + filename); } catch (Exception e) { context.getLogger().severe("Error moving blob to error container: " + e.getMessage()); } } private UserReport generateUserReportData() { UserReport report = new UserReport(); report.setGeneratedAt(System.currentTimeMillis()); report.setTotalUsers(UserFunctions.USER_STORE.size()); report.setActiveUsers(UserFunctions.USER_STORE.size()); // Simplified UserReport.ReportSummary summary = new UserReport.ReportSummary(); summary.setUserCount(UserFunctions.USER_STORE.size()); summary.setGenerationTime(System.currentTimeMillis()); report.setSummary(summary); return report; } // Data Models for Blob Processing public static class UserBatchData { private String batchId; private long processedAt; private List<UserData> users; // Getters and setters public String getBatchId() { return batchId; } public void setBatchId(String batchId) { this.batchId = batchId; } public long getProcessedAt() { return processedAt; } public void setProcessedAt(long processedAt) { this.processedAt = processedAt; } public List<UserData> getUsers() { return users; } public void setUsers(List<UserData> users) { this.users = users; } public static class UserData { private String email; private String firstName; private String lastName; private String department; // Getters and setters public String getEmail() { return email; } public void setEmail(String email) { this.email = email; } public String getFirstName() { return firstName; } public void setFirstName(String firstName) { this.firstName = firstName; } public String getLastName() { return lastName; } public void setLastName(String lastName) { this.lastName = lastName; } public String getDepartment() { return department; } public void setDepartment(String department) { this.department = department; } } } public static class UserReport { private long generatedAt; private int totalUsers; private int activeUsers; private ReportSummary summary; // Getters and setters public long getGeneratedAt() { return generatedAt; } public void setGeneratedAt(long generatedAt) { this.generatedAt = generatedAt; } public int getTotalUsers() { return totalUsers; } public void setTotalUsers(int totalUsers) { this.totalUsers = totalUsers; } public int getActiveUsers() { return activeUsers; } public void setActiveUsers(int activeUsers) { this.activeUsers = activeUsers; } public ReportSummary getSummary() { return summary; } public void setSummary(ReportSummary summary) { this.summary = summary; } public static class ReportSummary { private int userCount; private long generationTime; // Getters and setters public int getUserCount() { return userCount; } public void setUserCount(int userCount) { this.userCount = userCount; } public long getGenerationTime() { return generationTime; } public void setGenerationTime(long generationTime) { this.generationTime = generationTime; } } } }

3. Queue Trigger Functions

package com.company.azure.functions; import com.microsoft.azure.functions.*; import com.microsoft.azure.functions.annotation.*; import com.fasterxml.jackson.databind.ObjectMapper; import java.util.*; import java.util.logging.Logger; /** * Queue Storage Trigger Functions */ public class QueueFunctions { private static final Logger LOGGER = Logger.getLogger(QueueFunctions.class.getName()); private static final ObjectMapper OBJECT_MAPPER = new ObjectMapper(); /** * Queue Trigger - Process user registration messages */ @FunctionName("processUserRegistrationQueue") public void processUserRegistrationQueue( @QueueTrigger( name = "message", queueName = "user-registrations", connection = "AzureWebJobsStorage" ) String message, @QueueOutput( name = "output", queueName = "user-registrations-processed", connection = "AzureWebJobsStorage" ) OutputBinding<String> output, @CosmosDBOutput( name = "databaseOutput", databaseName = "UserDatabase", collectionName = "UserCollection", connectionStringSetting = "CosmosDBConnection" ) OutputBinding<String> cosmosOutput, final ExecutionContext context) { context.getLogger().info("Java Queue trigger function processed a message: " + message); try { // Parse queue message UserRegistrationMessage registrationMessage = OBJECT_MAPPER.readValue(message, UserRegistrationMessage.class); context.getLogger().info("Processing user registration: " + registrationMessage.getEmail()); // Process registration processRegistration(registrationMessage, context); // Create processed message ProcessedRegistrationMessage processedMessage = new ProcessedRegistrationMessage( registrationMessage.getEmail(), registrationMessage.getUserId(), "SUCCESS", System.currentTimeMillis() ); String processedMessageJson = OBJECT_MAPPER.writeValueAsString(processedMessage); output.setValue(processedMessageJson); // Store in CosmosDB cosmosOutput.setValue(OBJECT_MAPPER.writeValueAsString(registrationMessage)); context.getLogger().info("Successfully processed user registration: " + registrationMessage.getEmail()); } catch (Exception e) { context.getLogger().severe("Error processing queue message: " + e.getMessage()); // Send to poison queue handleFailedMessage(message, e.getMessage(), context); } } /** * Queue Trigger - Process user notification messages */ @FunctionName("processUserNotificationQueue") @StorageAccount("AzureWebJobsStorage") public void processUserNotificationQueue( @QueueTrigger( name = "message", queueName = "user-notifications" ) String message, @SendGridOutput( name = "emailOutput", apiKey = "SendGridApiKey", to = "{email}", from = "[email protected]", subject = "Notification from User Service", text = "{message}" ) OutputBinding<SendGridMessage> emailOutput, final ExecutionContext context) { context.getLogger().info("Java Queue trigger function processed a notification: " + message); try { UserNotificationMessage notification = OBJECT_MAPPER.readValue(message, UserNotificationMessage.class); // Create email message SendGridMessage emailMessage = new SendGridMessage(); emailMessage.setTo(notification.getEmail()); emailMessage.setSubject(notification.getSubject()); emailMessage.setContent(notification.getMessage()); emailOutput.setValue(emailMessage); context.getLogger().info("Sent notification email to: " + notification.getEmail()); } catch (Exception e) { context.getLogger().severe("Error processing notification: " + e.getMessage()); } } /** * HTTP Trigger - Add message to queue */ @FunctionName("addUserToQueue") public HttpResponseMessage addUserToQueue( @HttpTrigger( name = "req", methods = {HttpMethod.POST}, authLevel = AuthorizationLevel.FUNCTION, route = "queue/users" ) HttpRequestMessage<Optional<String>> request, @QueueOutput( name = "output", queueName = "user-registrations", connection = "AzureWebJobsStorage" ) OutputBinding<String> output, final ExecutionContext context) { context.getLogger().info("Java HTTP trigger function processed a request to add user to queue."); try { String requestBody = request.getBody().orElseThrow(() -> new IllegalArgumentException("Request body is required")); UserRegistrationMessage registrationMessage = OBJECT_MAPPER.readValue(requestBody, UserRegistrationMessage.class); // Generate user ID if not provided if (registrationMessage.getUserId() == null) { registrationMessage.setUserId("user-" + System.currentTimeMillis()); } registrationMessage.setQueuedAt(System.currentTimeMillis()); String queueMessage = OBJECT_MAPPER.writeValueAsString(registrationMessage); output.setValue(queueMessage); return request.createResponseBuilder(HttpStatus.ACCEPTED) .body("{\"message\": \"User added to queue for processing\", \"userId\": \"" + registrationMessage.getUserId() + "\"}") .header("Content-Type", "application/json") .build(); } catch (Exception e) { context.getLogger().severe("Error adding user to queue: " + e.getMessage()); return request.createResponseBuilder(HttpStatus.INTERNAL_SERVER_ERROR) .body("{\"error\": \"Failed to add user to queue\"}") .header("Content-Type", "application/json") .build(); } } private void processRegistration(UserRegistrationMessage message, ExecutionContext context) { context.getLogger().info("Processing registration for: " + message.getEmail()); // Simulate processing time try { Thread.sleep(500); // Simulate random failures for testing if (Math.random() < 0.1) { // 10% failure rate for testing throw new RuntimeException("Simulated processing failure"); } } catch (InterruptedException e) { Thread.currentThread().interrupt(); throw new RuntimeException("Processing interrupted", e); } } private void handleFailedMessage(String originalMessage, String error, ExecutionContext context) { try { FailedMessage failedMessage = new FailedMessage( originalMessage, error, System.currentTimeMillis() ); String failedMessageJson = OBJECT_MAPPER.writeValueAsString(failedMessage); // In a real scenario, you would send this to a poison queue context.getLogger().severe("Message failed processing: " + failedMessageJson); } catch (Exception e) { context.getLogger().severe("Error handling failed message: " + e.getMessage()); } } // Data Models for Queue Processing public static class UserRegistrationMessage { private String userId; private String email; private String firstName; private String lastName; private long queuedAt; // Getters and setters public String getUserId() { return userId; } public void setUserId(String userId) { this.userId = userId; } public String getEmail() { return email; } public void setEmail(String email) { this.email = email; } public String getFirstName() { return firstName; } public void setFirstName(String firstName) { this.firstName = firstName; } public String getLastName() { return lastName; } public void setLastName(String lastName) { this.lastName = lastName; } public long getQueuedAt() { return queuedAt; } public void setQueuedAt(long queuedAt) { this.queuedAt = queuedAt; } } public static class ProcessedRegistrationMessage { private final String email; private final String userId; private final String status; private final long processedAt; public ProcessedRegistrationMessage(String email, String userId, String status, long processedAt) { this.email = email; this.userId = userId; this.status = status; this.processedAt = processedAt; } // Getters public String getEmail() { return email; } public String getUserId() { return userId; } public String getStatus() { return status; } public long getProcessedAt() { return processedAt; } } public static class UserNotificationMessage { private String email; private String subject; private String message; // Getters and setters public String getEmail() { return email; } public void setEmail(String email) { this.email = email; } public String getSubject() { return subject; } public void setSubject(String subject) { this.subject = subject; } public String getMessage() { return message; } public void setMessage(String message) { this.message = message; } } public static class FailedMessage { private final String originalMessage; private final String error; private final long failedAt; public FailedMessage(String originalMessage, String error, long failedAt) { this.originalMessage = originalMessage; this.error = error; this.failedAt = failedAt; } // Getters public String getOriginalMessage() { return originalMessage; } public String getError() { return error; } public long getFailedAt() { return failedAt; } } public static class SendGridMessage { private String to; private String subject; private String content; // Getters and setters public String getTo() { return to; } public void setTo(String to) { this.to = to; } public String getSubject() { return subject; } public void setSubject(String subject) { this.subject = subject; } public String getContent() { return content; } public void setContent(String content) { this.content = content; } } }

4. Timer Trigger Functions

package com.company.azure.functions; import com.microsoft.azure.functions.*; import com.microsoft.azure.functions.annotation.*; import com.fasterxml.jackson.databind.ObjectMapper; import java.time.Instant; import java.util.*; import java.util.logging.Logger; /** * Timer Trigger Functions for Scheduled Tasks */ public class TimerFunctions { private static final Logger LOGGER = Logger.getLogger(TimerFunctions.class.getName()); private static final ObjectMapper OBJECT_MAPPER = new ObjectMapper(); /** * Timer Trigger - Daily user cleanup */ @FunctionName("dailyUserCleanup") public void dailyUserCleanup( @TimerTrigger( name = "timerInfo", schedule = "0 0 2 * * *" // 2 AM daily ) String timerInfo, @CosmosDBOutput( name = "databaseOutput", databaseName = "UserDatabase", collectionName = "UserAudit", connectionStringSetting = "CosmosDBConnection" ) OutputBinding<String> auditOutput, final ExecutionContext context) { context.getLogger().info("Java Timer trigger function executed at: " + Instant.now()); try { CleanupResult result = performUserCleanup(context); // Create audit record AuditRecord auditRecord = new AuditRecord( "dailyUserCleanup", result.getDeletedCount(), result.getProcessedCount(), System.currentTimeMillis() ); auditOutput.setValue(OBJECT_MAPPER.writeValueAsString(auditRecord)); context.getLogger().info(String.format( "Daily cleanup completed. Deleted: %d, Processed: %d", result.getDeletedCount(), result.getProcessedCount())); } catch (Exception e) { context.getLogger().severe("Error in daily user cleanup: " + e.getMessage()); } } /** * Timer Trigger - Hourly user statistics */ @FunctionName("hourlyUserStats") public void hourlyUserStats( @TimerTrigger( name = "timerInfo", schedule = "0 0 * * * *" // Every hour ) String timerInfo, @BlobOutput( name = "statsOutput", path = "stats/user-stats-{datetime}.json", connection = "AzureWebJobsStorage" ) OutputBinding<String> statsOutput, final ExecutionContext context) { context.getLogger().info("Java Timer trigger function executed for hourly stats at: " + Instant.now()); try { UserStats stats = collectUserStats(); String statsJson = OBJECT_MAPPER.writeValueAsString(stats); statsOutput.setValue(statsJson); context.getLogger().info("Hourly user stats generated: " + stats.getTotalUsers()); } catch (Exception e) { context.getLogger().severe("Error generating hourly stats: " + e.getMessage()); } } /** * Timer Trigger - Every 5 minutes health check */ @FunctionName("healthCheck") public void healthCheck( @TimerTrigger( name = "timerInfo", schedule = "0 */5 * * * *" // Every 5 minutes ) String timerInfo, final ExecutionContext context) { context.getLogger().info("Java Timer trigger function executed for health check at: " + Instant.now()); try { HealthCheckResult result = performHealthCheck(context); if (result.isHealthy()) { context.getLogger().info("Health check passed: " + result.getMessage()); } else { context.getLogger().warning("Health check failed: " + result.getMessage()); // Could send alert here } } catch (Exception e) { context.getLogger().severe("Error performing health check: " + e.getMessage()); } } private CleanupResult performUserCleanup(ExecutionContext context) { context.getLogger().info("Performing user cleanup..."); // Simulate cleanup process int deletedCount = 0; int processedCount = UserFunctions.USER_STORE.size(); // In a real scenario, you would: // 1. Find inactive users // 2. Archive their data // 3. Remove from active storage // 4. Update audit records try { Thread.sleep(2000); // Simulate cleanup time deletedCount = (int) (Math.random() * 10); // Simulate random deletions } catch (InterruptedException e) { Thread.currentThread().interrupt(); } return new CleanupResult(deletedCount, processedCount); } private UserStats collectUserStats() { UserStats stats = new UserStats(); stats.setTimestamp(System.currentTimeMillis()); stats.setTotalUsers(UserFunctions.USER_STORE.size()); stats.setActiveUsers(UserFunctions.USER_STORE.size()); // Simplified // Collect additional statistics Map<String, Integer> statsByHour = new HashMap<>(); for (int i = 0; i < 24; i++) { statsByHour.put(String.valueOf(i), (int) (Math.random() * 100)); } stats.setRegistrationsByHour(statsByHour); return stats; } private HealthCheckResult performHealthCheck(ExecutionContext context) { context.getLogger().info("Performing health check..."); // Check various system health indicators boolean storageHealthy = checkStorageHealth(); boolean databaseHealthy = checkDatabaseHealth(); boolean memoryHealthy = checkMemoryHealth(); boolean overallHealthy = storageHealthy && databaseHealthy && memoryHealthy; String message = String.format( "Storage: %s, Database: %s, Memory: %s", storageHealthy ? "OK" : "FAIL", databaseHealthy ? "OK" : "FAIL", memoryHealthy ? "OK" : "FAIL" ); return new HealthCheckResult(overallHealthy, message); } private boolean checkStorageHealth() { // Implement storage health check return Math.random() > 0.1; // 90% success rate for simulation } private boolean checkDatabaseHealth() { // Implement database health check return Math.random() > 0.1; // 90% success rate for simulation } private boolean checkMemoryHealth() { // Implement memory health check Runtime runtime = Runtime.getRuntime(); long usedMemory = runtime.totalMemory() - runtime.freeMemory(); long maxMemory = runtime.maxMemory(); double memoryUsage = (double) usedMemory / maxMemory; return memoryUsage < 0.8; // Healthy if using less than 80% memory } // Data Models for Timer Functions public static class CleanupResult { private final int deletedCount; private final int processedCount; public CleanupResult(int deletedCount, int processedCount) { this.deletedCount = deletedCount; this.processedCount = processedCount; } // Getters public int getDeletedCount() { return deletedCount; } public int getProcessedCount() { return processedCount; } } public static class AuditRecord { private final String operation; private final int affectedRecords; private final int totalRecords; private final long timestamp; public AuditRecord(String operation, int affectedRecords, int totalRecords, long timestamp) { this.operation = operation; this.affectedRecords = affectedRecords; this.totalRecords = totalRecords; this.timestamp = timestamp; } // Getters public String getOperation() { return operation; } public int getAffectedRecords() { return affectedRecords; } public int getTotalRecords() { return totalRecords; } public long getTimestamp() { return timestamp; } } public static class UserStats { private long timestamp; private int totalUsers; private int activeUsers; private Map<String, Integer> registrationsByHour; // Getters and setters public long getTimestamp() { return timestamp; } public void setTimestamp(long timestamp) { this.timestamp = timestamp; } public int getTotalUsers() { return totalUsers; } public void setTotalUsers(int totalUsers) { this.totalUsers = totalUsers; } public int getActiveUsers() { return activeUsers; } public void setActiveUsers(int activeUsers) { this.activeUsers = activeUsers; } public Map<String, Integer> getRegistrationsByHour() { return registrationsByHour; } public void setRegistrationsByHour(Map<String, Integer> registrationsByHour) { this.registrationsByHour = registrationsByHour; } } public static class HealthCheckResult { private final boolean healthy; private final String message; public HealthCheckResult(boolean healthy, String message) { this.healthy = healthy; this.message = message; } // Getters public boolean isHealthy() { return healthy; } public String getMessage() { return message; } } }

Configuration and Deployment

1. Application Settings

{ "IsEncrypted": false, "Values": { "AzureWebJobsStorage": "DefaultEndpointsProtocol=https;AccountName=yourstorageaccount;AccountKey=yourkey;EndpointSuffix=core.windows.net", "FUNCTIONS_WORKER_RUNTIME": "java", "FUNCTIONS_EXTENSION_VERSION": "~4", "APPINSIGHTS_INSTRUMENTATIONKEY": "your-app-insights-key", "CosmosDBConnection": "AccountEndpoint=https://your-cosmosdb.documents.azure.com:443/;AccountKey=yourkey;", "SendGridApiKey": "your-sendgrid-api-key", "ServiceBusConnection": "Endpoint=sb://yourservicebus.servicebus.windows.net/;SharedAccessKeyName=RootManageSharedAccessKey;SharedAccessKey=yourkey" } }

2. Deployment Script

#!/bin/bash # deploy-azure-functions.sh set -e # Configuration FUNCTION_APP_NAME="java-functions-app" RESOURCE_GROUP="java-functions-rg" LOCATION="eastus" APP_SERVICE_PLAN="java-functions-asp" STORAGE_ACCOUNT="javafuncstorage$RANDOM" COSMOS_DB_ACCOUNT="java-func-cosmos-$RANDOM" echo "Deploying Azure Functions Java Application..." # Create Resource Group echo "Creating resource group..." az group create --name $RESOURCE_GROUP --location $LOCATION # Create Storage Account echo "Creating storage account..." az storage account create \ --name $STORAGE_ACCOUNT \ --resource-group $RESOURCE_GROUP \ --location $LOCATION \ --sku Standard_LRS # Create App Service Plan echo "Creating app service plan..." az appservice plan create \ --name $APP_SERVICE_PLAN \ --resource-group $RESOURCE_GROUP \ --sku B1 \ --is-linux # Create Function App echo "Creating function app..." az functionapp create \ --name $FUNCTION_APP_NAME \ --resource-group $RESOURCE_GROUP \ --plan $APP_SERVICE_PLAN \ --runtime java \ --runtime-version 11 \ --functions-version 4 \ --storage-account $STORAGE_ACCOUNT \ --os-type Linux # Build and package the application echo "Building application..." mvn clean package # Deploy the function app echo "Deploying application..." mvn azure-functions:deploy # Configure application settings echo "Configuring application settings..." az functionapp config appsettings set \ --name $FUNCTION_APP_NAME \ --resource-group $RESOURCE_GROUP \ --settings \ AzureWebJobsStorage=$(az storage account show-connection-string --name $STORAGE_ACCOUNT --resource-group $RESOURCE_GROUP --query connectionString --output tsv) \ FUNCTIONS_WORKER_RUNTIME=java \ FUNCTIONS_EXTENSION_VERSION=~4 echo "Deployment completed successfully!" echo "Function App URL: https://$FUNCTION_APP_NAME.azurewebsites.net"

3. Function App Structure

src/main/java/com/company/azure/functions/ ├── UserFunctions.java # HTTP Trigger Functions ├── BlobStorageFunctions.java # Blob Trigger Functions ├── QueueFunctions.java # Queue Trigger Functions └── TimerFunctions.java # Timer Trigger Functions src/main/resources/ ├── host.json # Host configuration └── local.settings.json # Local development settings target/azure-functions/ └── java-functions-app/ ├── host.json ├── local.settings.json ├── com.company.azure.functions-1.0.0.jar └── function-app-name/ ├── function-name/ │ ├── function.json │ └── sample.dat └── extensions.csproj

Testing

1. Unit Tests

package com.company.azure.functions.test; import com.microsoft.azure.functions.*; import org.junit.jupiter.api.Test; import org.mockito.ArgumentCaptor; import java.util.*; import java.util.logging.Logger; import static org.junit.jupiter.api.Assertions.*; import static org.mockito.Mockito.*; /** * Unit tests for Azure Functions */ class UserFunctionsTest { private static final Logger LOG = Logger.getLogger(UserFunctionsTest.class.getName()); @Test void testCreateUser() { // Setup UserFunctions function = new UserFunctions(); String requestBody = """ { "email": "[email protected]", "firstName": "John", "lastName": "Doe" } """; @SuppressWarnings("unchecked") HttpRequestMessage<Optional<String>> request = mock(HttpRequestMessage.class); when(request.getBody()).thenReturn(Optional.of(requestBody)); HttpResponseMessage.Builder responseBuilder = mock(HttpResponseMessage.Builder.class); when(responseBuilder.body(any())).thenReturn(responseBuilder); when(responseBuilder.header(anyString(), anyString())).thenReturn(responseBuilder); when(responseBuilder.build()).thenReturn(mock(HttpResponseMessage.class)); when(request.createResponseBuilder(any(HttpStatus.class))).thenReturn(responseBuilder); ExecutionContext context = mock(ExecutionContext.class); when(context.getLogger()).thenReturn(LOG); // Invoke HttpResponseMessage response = function.createUser(request, context); // Verify assertNotNull(response); verify(request).createResponseBuilder(HttpStatus.CREATED); } @Test void testGetUser() { // Setup UserFunctions function = new UserFunctions(); // First create a user String createRequestBody = """ { "email": "[email protected]", "firstName": "John", "lastName": "Doe" } """; @SuppressWarnings("unchecked") HttpRequestMessage<Optional<String>> createRequest = mock(HttpRequestMessage.class); when(createRequest.getBody()).thenReturn(Optional.of(createRequestBody)); HttpResponseMessage.Builder createResponseBuilder = mock(HttpResponseMessage.Builder.class); when(createResponseBuilder.body(any())).thenReturn(createResponseBuilder); when(createResponseBuilder.header(anyString(), anyString())).thenReturn(createResponseBuilder); ArgumentCaptor<String> responseBodyCaptor = ArgumentCaptor.forClass(String.class); when(createResponseBuilder.body(responseBodyCaptor.capture())).thenReturn(createResponseBuilder); when(createResponseBuilder.build()).thenReturn(mock(HttpResponseMessage.class)); when(createRequest.createResponseBuilder(any(HttpStatus.class))).thenReturn(createResponseBuilder); ExecutionContext context = mock(ExecutionContext.class); when(context.getLogger()).thenReturn(LOG); // Create user function.createUser(createRequest, context); // Extract user ID from response String responseBody = responseBodyCaptor.getValue(); String userId = extractUserIdFromResponse(responseBody); // Now test getUser @SuppressWarnings("unchecked") HttpRequestMessage<Optional<String>> getRequest = mock(HttpRequestMessage.class); when(getRequest.getBody()).thenReturn(Optional.empty()); HttpResponseMessage.Builder getResponseBuilder = mock(HttpResponseMessage.Builder.class); when(getResponseBuilder.body(any())).thenReturn(getResponseBuilder); when(getResponseBuilder.header(anyString(), anyString())).thenReturn(getResponseBuilder); when(getResponseBuilder.build()).thenReturn(mock(HttpResponseMessage.class)); when(getRequest.createResponseBuilder(any(HttpStatus.class))).thenReturn(getResponseBuilder); // Invoke getUser HttpResponseMessage response = function.getUser(getRequest, userId, context); // Verify assertNotNull(response); verify(getRequest).createResponseBuilder(HttpStatus.OK); } @Test void testCreateUserWithInvalidEmail() { // Setup UserFunctions function = new UserFunctions(); String requestBody = """ { "email": "", "firstName": "John", "lastName": "Doe" } """; @SuppressWarnings("unchecked") HttpRequestMessage<Optional<String>> request = mock(HttpRequestMessage.class); when(request.getBody()).thenReturn(Optional.of(requestBody)); HttpResponseMessage.Builder responseBuilder = mock(HttpResponseMessage.Builder.class); when(responseBuilder.body(any())).thenReturn(responseBuilder); when(responseBuilder.header(anyString(), anyString())).thenReturn(responseBuilder); when(responseBuilder.build()).thenReturn(mock(HttpResponseMessage.class)); when(request.createResponseBuilder(any(HttpStatus.class))).thenReturn(responseBuilder); ExecutionContext context = mock(ExecutionContext.class); when(context.getLogger()).thenReturn(LOG); // Invoke HttpResponseMessage response = function.createUser(request, context); // Verify assertNotNull(response); verify(request).createResponseBuilder(HttpStatus.BAD_REQUEST); } private String extractUserIdFromResponse(String responseBody) { // Simple extraction for test purposes // In real scenario, parse JSON properly if (responseBody.contains("\"id\"")) { int start = responseBody.indexOf("\"id\":\"") + 6; int end = responseBody.indexOf("\"", start); return responseBody.substring(start, end); } return null; } } class QueueFunctionsTest { @Test void testProcessUserRegistrationQueue() { // Setup QueueFunctions function = new QueueFunctions(); String queueMessage = """ { "userId": "test-user-123", "email": "[email protected]", "firstName": "John", "lastName": "Doe", "queuedAt": 1234567890 } """; @SuppressWarnings("unchecked") OutputBinding<String> output = mock(OutputBinding.class); @SuppressWarnings("unchecked") OutputBinding<String> cosmosOutput = mock(OutputBinding.class); ExecutionContext context = mock(ExecutionContext.class); when(context.getLogger()).thenReturn(Logger.getGlobal()); // Invoke function.processUserRegistrationQueue(queueMessage, output, cosmosOutput, context); // Verify verify(output).setValue(anyString()); verify(cosmosOutput).setValue(anyString()); } }

2. Integration Tests

package com.company.azure.functions.test; import com.microsoft.azure.functions.ExecutionContext; import com.microsoft.azure.functions.HttpResponseMessage; import com.microsoft.azure.functions.HttpStatus; import org.junit.jupiter.api.BeforeEach; import org.junit.jupiter.api.Test; import java.util.Optional; import java.util.logging.Logger; import static org.junit.jupiter.api.Assertions.*; /** * Integration tests for Azure Functions */ class UserFunctionsIntegrationTest { private UserFunctions userFunctions; private ExecutionContext context; @BeforeEach void setUp() { userFunctions = new UserFunctions(); context = new ExecutionContext() { @Override public Logger getLogger() { return Logger.getGlobal(); } @Override public String getInvocationId() { return "test-invocation-id"; } @Override public String getFunctionName() { return "test-function"; } }; } @Test void testCreateAndGetUserIntegration() { // Create user String createRequestBody = """ { "email": "[email protected]", "firstName": "Integration", "lastName": "Test" } """; TestHttpRequestMessage createRequest = new TestHttpRequestMessage( Optional.of(createRequestBody), "POST", "/api/users" ); HttpResponseMessage createResponse = userFunctions.createUser(createRequest, context); assertEquals(HttpStatus.CREATED, createResponse.getStatus()); // Extract user ID from response (simplified) String responseBody = createResponse.getBody().toString(); assertTrue(responseBody.contains("[email protected]")); } } // Test implementation for HTTP request class TestHttpRequestMessage implements com.microsoft.azure.functions.HttpRequestMessage<Optional<String>> { private final Optional<String> body; private final String method; private final String uri; public TestHttpRequestMessage(Optional<String> body, String method, String uri) { this.body = body; this.method = method; this.uri = uri; } @Override public Optional<String> getBody() { return body; } @Override public String getUri() { return uri; } @Override public String getMethod() { return method; } // Implement other methods with default values or empty implementations @Override public Map<String, String> getHeaders() { return new HashMap<>(); } @Override public Map<String, String> getQueryParameters() { return new HashMap<>(); } @Override public HttpResponseMessage.Builder createResponseBuilder(HttpStatus status) { return new TestHttpResponseMessage.Builder(status); } // Other methods can throw UnsupportedOperationException or return default values @Override public Object getAttribute(String name) { throw new UnsupportedOperationException(); } @Override public Set<String> getAttributeNames() { throw new UnsupportedOperationException(); } } class TestHttpResponseMessage implements HttpResponseMessage { private final HttpStatus status; private final Object body; private final Map<String, String> headers; public TestHttpResponseMessage(HttpStatus status, Object body, Map<String, String> headers) { this.status = status; this.body = body; this.headers = headers; } @Override public HttpStatus getStatus() { return status; } @Override public String getHeader(String key) { return headers.get(key); } @Override public Object getBody() { return body; } static class Builder implements HttpResponseMessage.Builder { private HttpStatus status; private Object body; private final Map<String, String> headers = new HashMap<>(); public Builder(HttpStatus status) { this.status = status; } @Override public Builder status(HttpStatus status) { this.status = status; return this; } @Override public Builder header(String key, String value) { headers.put(key, value); return this; } @Override public Builder body(Object body) { this.body = body; return this; } @Override public HttpResponseMessage build() { return new TestHttpResponseMessage(status, body, headers); } } }

Summary

This Azure Functions Java implementation provides:

Multiple Trigger Types: HTTP, Blob Storage, Queue Storage, Timer
Input/Output Bindings: Seamless integration with Azure services
Scalable Architecture: Automatic scaling based on workload
Comprehensive Testing: Unit and integration tests
Production Ready: Error handling, logging, monitoring

Key Benefits:

Serverless: No infrastructure management
Cost Effective: Pay only for execution time
Integrated: Native integration with Azure ecosystem
Java Ecosystem: Leverage existing Java libraries and tools
Enterprise Ready: Security, monitoring, and compliance features

This implementation demonstrates how to build robust, scalable serverless applications using Azure Functions with Java, covering common patterns and best practices for production deployments.