Projects/docs/ReviewApplication.md

🧩 1. Service Layer (Business Logic)

These classes orchestrate repositories, apply business rules, and are called by route handlers. Many are referenced in your route files (e.g., ArticleRoutes, AuthRoutes, MessagingRoutes) but are missing or only stubs.

Service	Methods to Implement
UserService	register, login, findUserByUsername, updateProfile, changeEmail, changePassword, deactivate, follow, unfollow, getFollowers, getFollowing, getProfile (public/private), updateSecurityQuestion, updateNotificationSettings, getNotificationSettings, saveAvatar, getBookmarks, toggleBookmark, getRecentActivity, updateLastActive, isPrivate, etc.
ArticleService	create, update, delete, getArticle, getArticleDTO, search (with filters & pagination), getAllArticles, getArticlesByAuthor, toggleLike, isLikedBy, addComment, deleteComment, getComments, generateCitation, getAnalytics (user), getArticleAnalytics (views over time), incrementViewCount, getTrendingArticles, getFeaturedArticles, getGraphRecommendations (co‑citation, bibliographic, PageRank), publishDraft, batchDelete, batchPublish.
MessageService	sendMessage, getConversation, getMessagesBefore, getMessagesAfter, markAllRead, editMessage, deleteMessage, forwardMessage, getLastReadId, updateLastRead, recordTyping, isUserTyping, archiveConversation, unarchiveConversation, getArchivedConversations, sendEphemeral, scheduleMessage, getScheduledMessages, cancelScheduledMessage, getThreadReplies, replyToMessage, getEditHistory, getPrivateReactions, togglePrivateReaction.
GroupService	createGroup, getGroup, listUserGroups, updateGroup, deleteGroup, addMember, removeMember, promoteToAdmin, demoteFromAdmin, leaveGroup, generateInviteToken, joinByInviteToken, sendMessage, editMessage, deleteMessage, getMessages, getMessagesBefore, getMessagesSince, pinMessage, unpinMessage, getPinnedMessages, muteGroup, unmuteGroup, getMutedGroups, searchMessages, createPoll, getPoll, votePoll, closePoll, reopenPoll, deletePoll, getPollResults, getReactions, toggleReaction.
NotificationService	createNotification, getUserNotifications, markAsRead, markAllAsRead, deleteNotification, deleteAllForUser, getUnreadCount, sendRealTimeNotification (via WebSocket), getNotificationById.
AnalyticsService	getUserStats (total articles, likes, comments, views, followers, etc.), getUserViewsOverTime, getTopArticlesForUser, getAdminStats (platform), getPlatformActivity, getTopContributors, getArticleAnalytics (views, likes, comments per day), getDailyViews, getReferrerStats, getDemographics, getCitationMetrics, setViewThresholdAlert, getActiveAlerts, deleteAlert, getTrendingArticles, getPopularTags.
GapAnalysisService	getAllNodes, getNode, addNode, updateNode, deleteNode, searchNodes, getNodesByType, getAllEdges, getEdge, addEdge, updateEdge, deleteEdge, getEdgesForNode, getEdgesByType, getNodeDegrees, analyzeGap (AI), generateHypothesis, importGraph, exportGraph.
GrantService	getUpcomingGrants, getGrantsForUser, addGrant, updateGrant, deleteGrant, generateDraft (AI), analyzeRFP.
ProjectService	createProject, getUserProjects, getProjectsUserIsMember, getProject, updateProject, deleteProject, addMember, removeMember, setMemberRole, getMemberRole, getMemberJoinedAt, addTask, getTasksForProject, getTask, updateTask, moveTask, deleteTask, addOutput, removeOutput.
DataHubService	getUserResearchObjects, getAllResearchObjects, getResearchObject, addResearchObject, updateResearchObject, deleteResearchObject, incrementResearchObjectView, incrementResearchObjectDownload, getUserProtocols, getAllProtocols, getProtocol, addProtocol, updateProtocol, deleteProtocol, forkProtocol, getProtocolSteps, addProtocolStep, updateProtocolStep, deleteProtocolStep, getUserPreregistrations, getPreregistration, addPreregistration, updatePreregistration, updatePreregistrationSection, submitPreregistration, deletePreregistration.
PollService	createPoll, getPoll, updatePoll, deletePoll, vote, getUserVote, getPollResults, getPollAnalytics, exportResultsToCsv, getPollsByCreator, getPollTemplates, instantiateTemplate, schedulePoll, setPollPrivacy, searchPolls, deleteExpiredPolls, hasAnyVotes, isUserInGroup, isUserInProject.
EventService	listEvents, getUpcomingEvents, getUserEvents, getEvent, createEvent, updateEvent, deleteEvent, incrementViewCount, setAttendeeStatus, getAttendees, addReminder, getRemindersForUser, deleteReminder, createRecurringEvents, exportUserEventsToIcal, searchEvents.
LabInventoryService	getAllChemicals, getChemical, addChemical, updateChemical, deleteChemical, getLowStockCount, getExpiringSoonCount, getExpiredCount, getUnacknowledgedAlertsCount, getAllLocations, getSupplierCount, getTotalScanCount, getRecentlyAdded, getTopExpiring, getCountByLocation, getCountByType, getIncompatibilities, areCompatible, checkAndCreateAlerts, acknowledgeAlert, acknowledgeAllAlertsForChemical, createAlert, getAlert, deleteAlert, getChemicalByBarcode, getChemicalByCasNumber, incrementScanCount.
PeerReviewService	submitPaper, getSubmissionById, getOpenSubmissions, getSubmissionsByStatus, getSubmissionsAssignedToReviewer, assignReviewer, submitReview, getReviewById, getReviewsForSubmission, getReviewsByReviewer, getReviewerCredential, saveReviewerCredential, deleteReviewerCredential, getAllSubmissions, getAllReviews, deleteSubmission.
WorkspaceService	getUserPanels, getPanelById, createPanel, updatePanel, renamePanel, deletePanel, duplicatePanel, reorderPanels, exportWorkspaceToJson, importWorkspaceFromJson, clearAllPanels, getBuiltInPresets, applyPreset, createShareToken, getSharedPanel, getActivePanel, setActivePanel, createBackup, restoreBackup, listBackups, deleteBackup.
VoiceSettingsService	getSettings, updateSettings, resetToDefault, getAllProfiles, getProfile, saveProfile, deleteProfile, activateProfile, getLanguageOverrides, setLanguageOverrides, getAvailableTtsVoices, generateTestAudio, listWakeWords, addWakeWord, removeWakeWord, getCustomGrammar, setCustomGrammar, exportAllSettings, importAllSettings.
RagService	chatSimple, chat (RAG), getAvailableModels, getSuggestedQuestions, indexDocument, getIndexingStatus, getUserDocuments, deleteDocument, getConversationHistory, clearConversationHistory, deleteMessageFromHistory, predictCommands, clearAllHistory, reindexAllDocuments, getRagStats, isLLMHealthy, getEmbeddingModelInfo.
PasswordResetService	getSecurityQuestion, resetPassword.
TwoFactorService	generateSecret, getQrCode, verifyCode, enableTwoFactor, disableTwoFactor, generateBackupCodes, getBackupCodes, regenerateBackupCodes.
SearchService	search (messages), getIndexedCount (full‑text search statistics).
MediaService	uploadMedia, getMedia, deleteMedia, updateMediaGroupMessageId.
RateLimitService	allowRequest (uses TokenBucket).
ContentModeration	moderate (check profanity), censor.
CitationGraphService	getCoCitationRecommendations, getBibliographicCouplingRecommendations, getPageRankRecommendations.
GNNRecommendationService	getPersonalizedFeed, getContextualRecommendations, getTrendingArticles, getSimilarArticles, getSuggestedUsers, getUsersByInterest, recordFeedback, getPersonalizedTrending, refresh, fullRetrain, getModelStats, resetModel, setEnabled.
RecommendationService	getPersonalizedFeed, getTrendingArticles, getTrendingArticlesByCategory, getTrendingArticlesByTimeRange, getSimilarArticles, getArticlesByTags, getSuggestedUsers, getSuggestedUsersByInterest, getHybridFeed, recordFeedback, getUserRecommendationHistory, refreshModel, fullRetrain, getModelStats, resetModel.

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🧩 2. Controllers / Route Handlers (Missing Endpoints)

Even though you have route skeleton files (e.g., ArticleRoutes, AuthRoutes), many endpoints are not implemented. Below are the missing route handlers (grouped by feature).

Feature	Missing Endpoints	Required Service
Recent Items	GET /api/recent-items	UserService (or new RecentItemService)
Unified Inbox	GET /api/unified-inbox	UnifiedInboxService (aggregate messages, notifications, paper Q&A, broadcasts)
Discovery	GET /api/discovery/digest GET /api/discovery/recommendations	NotificationService RecommendationService (alias)
User liked articles	GET /api/users/me/liked-articles	ArticleService
Messaging last read	GET /api/conversations/{username}/last-read	MessageService (call /read-status)
Secret chat keys	GET /api/conversations/{username}/keys	EncryptionKeyRepository (already exists)
Group pinned messages	GET /api/groups/{groupId}/pinned	GroupService (alias to /pins)
Paper Collections	GET /api/collections POST /api/collections DELETE /api/collections/{id} POST /api/collections/{id}/papers DELETE /api/collections/{id}/papers/{paperId}	CollectionService (new) + CollectionRepository
Reference Manager	GET /api/documents/{docId}/references POST /api/documents/{docId}/references PUT /api/documents/{docId}/references/{refId} DELETE /api/documents/{docId}/references/{refId} POST /api/references/connect-zotero POST /api/references/connect-mendeley	ReferenceService + ReferenceRepository
Preprint Submission	POST /api/preprints/screen POST /api/preprints/submit	PreprintService + PreprintRepository
Provenance	GET /api/provenance/{entityType}/{entityId} POST /api/provenance/{entityType}/{entityId}/verify	ProvenanceService + ProvenanceEventRepository
Export	POST /api/ai/export POST /api/documents/{docId}/export	ExportService (calls external converter)

Additionally, you need to implement the route files that are currently stubs: ArticleRoutes, AuthRoutes, MessagingRoutes, UserRoutes, AnalyticsRoutes, etc. – they contain placeholder // TODO or empty method bodies.

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🧩 3. DTOs (Data Transfer Objects)

Many route handlers return or consume DTOs. You already have some (e.g., ArticleDTO, CreateArticleRequest), but many are missing.

DTO	Purpose	Used In
ArticleDTO	Return article metadata (without full body for lists)	ArticleService
CreateArticleRequest	Input for article creation	ArticleService
CommentDTO	Comment data (id, author, body, createdAt)	ArticleService
UserProfileDTO	Public profile information	UserService
UserSettingsDTO	Notification, privacy, security settings	UserService
AnalyticsDTO	User analytics (total views, likes, etc.)	AnalyticsService
ViewStatDTO	Daily views (date, count)	AnalyticsService
MessageDTO	Private message representation (without internal fields)	MessageService
GroupMessageDTO	Group message representation	GroupService
ConversationDTO	Private conversation summary (with, lastMessage, unread)	MessageService
GroupDTO	Group metadata (id, name, memberCount, lastMessage)	GroupService
MemberDTO	Group member (userId, username, role)	GroupService
PollDTO	Poll/quiz data (question, options, results)	PollService
PollVoteDTO	Vote submission	PollService
ChemicalDTO	Chemical inventory item (with NFPA, location, expiry)	LabInventoryService
AlertDTO	Inventory alert	LabInventoryService
EventDTO	Event details (title, startTime, location, host)	EventService
ProjectDTO	Project summary	ProjectService
TaskDTO	Kanban task	ProjectService
ProtocolDTO	Protocol with steps	DataHubService
PreregistrationDTO	Preregistration (template, sections)	DataHubService
ResearchObjectDTO	Object metadata (type, title, authors, DOI)	DataHubService
GrantDTO	Grant deadline (name, agency, deadline, amount)	GrantService
RecommendationResultDTO	Recommended article (id, title, score, tags)	RecommendationService
ScreeningResultDTO	Preprint screening result	PreprintService
BackupCodesDTO	List of backup codes	TwoFactorService
TwoFactorSecretDTO	Secret + QR code for 2FA setup	TwoFactorService
VoiceSettingsDTO	Voice assistant configuration	VoiceSettingsService
WorkspacePanelDTO	Panel layout (type, title, props, position)	WorkspaceService
WorkspacePresetDTO	Preset definition	WorkspaceService

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🧩 4. Utilities & Helper Classes

Utility	Description	Required By
JsonUtils	Jackson object mapper wrapper (you already have it in util)	All route handlers
TokenUtil	Extract JWT from Authorization header	AuthUtils, AuthRoutes
SessionManager	Create, validate, refresh sessions; manage CSRF tokens; store username → token mapping; invalidate sessions	AuthUtils, AuthRoutes
WebSocketManager	Manage active WebSocket sessions, send messages to specific users, broadcast to groups/topics	MessagingRoutes, NotificationService
RateLimitService	Use TokenBucket to check if request is allowed	MessagingRoutes, AuthRoutes
ContentModeration	Filter profanity using a word list or external API	MessagingRoutes
MailService	Send emails (verification, password reset, invitation, daily digests)	UserService, PasswordResetService, NotificationService
FileStorageService	Save uploaded files (avatars, manuscripts, research objects, etc.) to disk/cloud; return URL	UserService, PeerReviewService, DataHubService
CitationGenerator	Convert article metadata to APA/MLA/BibTeX string	ArticleService
ExportConverter	Convert HTML to PDF, DOCX, LaTeX (possibly using external tools like wkhtmltopdf, Pandoc)	ExportService
PasswordEncoder	BCrypt hashing for passwords	UserService (already used)
TotpUtil	Generate TOTP secret, QR code URI, verify code (wrapper around Google Authenticator)	TwoFactorService
HtmlSanitizer	Sanitize HTML from editor (prevent XSS)	ArticleService, MessageService
MarkdownConverter	Convert markdown to HTML (if needed)	ArticleService
CacheManager	Simple in‑memory cache (e.g., for frequently requested articles)	Optional – performance
AsyncTaskExecutor	Execute long‑running tasks asynchronously (e.g., document indexing, email sending)	RagService, MailService
ScheduledTaskManager	Schedule jobs (e.g., daily digest, cleanup expired tokens)	NotificationService, SessionManager
ApiError	Standard error response structure	All controllers
GlobalExceptionHandler	Catch exceptions and return appropriate HTTP status codes	All controllers
ValidationUtils	Validate email, username, password strength	UserService, AuthRoutes

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🧩 5. Security & Configuration

Component	Description
JwtUtil	Generate and parse JWT tokens (claims, expiration)
CsrfTokenManager	Generate and validate CSRF tokens per session
CorsConfig	Configure CORS for frontend origin
WebSecurityConfig (Spring)	Define which endpoints are public, which require authentication
PasswordEncoder bean	BCryptPasswordEncoder
AuthenticationProvider (if using Spring Security)	Custom authentication logic
ApplicationProperties	Read environment variables (database URL, API keys, mail settings)
DatabaseInitializer	Create tables on startup (if using auto‑migration)

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🧩 6. WebSocket & SSE

Component	Description
WebSocketHandler (or @ServerEndpoint)	Handle WebSocket connections for messaging, typing, presence, reactions.
WebSocketConfig	Register the WebSocket endpoint (/ws) and configure STOMP (if using) or raw WebSocket.
SseEmitterManager (SSE)	Manage SSE connections for notifications, keep‑alive, event replay.
WebSocketMessage	DTO for messages sent over WebSocket (type, payload).

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🧩 7. Database Migration & Schema

Even though you have repository classes, you must create the actual SQL tables. Provide SQL scripts (or use Flyway/Liquibase) for all entities:

• users
• articles
• comments
• tags (article_tags)
• messages
• conversations
• groups
• group_members
• group_messages
• polls, poll_options, poll_votes
• reactions (or store inside messages)
• notifications
• chemicals, alerts
• events, event_attendees, event_reminders
• projects, project_members, project_tasks, project_outputs
• research_objects
• protocols, protocol_steps
• preregistrations, preregistration_sections
• grants
• graph_nodes, graph_edges
• workspace_panels
• voice_settings
• paper_collections, collection_papers
• managed_references, reference_groups
• preprints
• provenance_events
• pre_keys, signed_pre_keys
• encryption_keys (for secret chats)

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🧩 8. Additional Supporting Code

Component	Description
Custom Exceptions	ResourceNotFoundException, UnauthorizedException, BadRequestException, ConflictException, etc.
Validation Annotations	@ValidUsername, @ValidPassword (custom) – optional
Audit Fields	CreatedAt, UpdatedAt automatically set (use @PrePersist, @PreUpdate in JPA)
Pagination Helper	Convert page/limit parameters to offset/limit and return paginated responses
Date/Time Formatter	Consistent ISO‑8601 formatting
Health Check Endpoint	GET /health (already present)
Metrics Endpoint	GET /metrics for Prometheus (optional)
API Documentation	Swagger/OpenAPI configuration (springdoc-openapi)
Dockerfile	Containerise the backend
CI/CD Pipeline	GitHub Actions / Jenkins (optional)

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✅ What You Already Have (from your files)

• Models – almost complete (User, Article, Comment, Message, GroupChat, GroupMessage, Poll, Chemical, etc.) – you provided many .java files.
• Repositories – you have JDBC‑based repositories (ArticleRepository, UserRepository, etc.). They are functional but may need small adjustments.
• Route skeletons – you have ArticleRoutes, AuthRoutes, MessagingRoutes, etc., but many methods are empty or only print logs. They need to be filled with actual business logic.
• Some utilities – JsonUtils, RouteUtils, AuthUtils, TokenBucket, etc.

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🎯 Final Recommendation

Start by implementing the services (the longest list). Then fill in the route handlers (one by one, based on frontend needs). Create DTOs as you go. The utilities (Mail, FileStorage, WebSocket, etc.) can be added later but are required for full functionality.

🚀 1. Infrastructure & Architecture

Component	Technology / Implementation	Why It’s Needed
API Gateway	Spring Cloud Gateway, Kong, NGINX	Route external traffic to the correct backend service, handle SSL termination, rate limiting, authentication at the edge.
Service Discovery	Netflix Eureka, Consul, Kubernetes Service	If you split into microservices, services need to find each other dynamically.
Load Balancer	Spring Cloud LoadBalancer, HAProxy, AWS ALB	Distribute traffic across multiple instances of your backend.
Reverse Proxy + CDN	CloudFront, Cloudflare, Fastly	Serve static assets (React build) globally, cache API responses, protect against DDoS.
WebSocket Server	Spring WebSocket + STOMP (separate instance)	Handle real‑time messaging independently, scale horizontally.
Database	PostgreSQL / MySQL (with read replicas)	Primary relational store; read replicas for high‑load queries.
Database Pooling	HikariCP (default in Spring Boot)	Efficiently manage database connections.
Distributed Cache	Redis, Caffeine	Cache frequently accessed data (user profiles, session, rate limits, computed recommendations).
Message Queue	RabbitMQ, Apache Kafka	Process long‑running tasks asynchronously: sending emails, indexing documents, generating reports, AI inference.
Object Storage	AWS S3, MinIO (self‑hosted)	Store uploaded files (avatars, manuscripts, research objects, voice notes). Generate presigned URLs for secure access.
Search Engine	Elasticsearch, OpenSearch	Full‑text search across articles, messages, users, grants, chemicals – far faster than SQL LIKE.
Distributed Locking	Redis Redlock	Prevent race conditions (e.g., two users claiming same peer‑review assignment).

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🔐 2. Security

Component	Technology	Purpose
OAuth2 / OpenID Connect	Spring Security OAuth2, Keycloak, Auth0	Let users log in with Google, ORCID, institutional SSO.
JWT Refresh Tokens	Custom implementation	Short‑lived access tokens + refresh token stored in http‑only cookie for better security.
CSRF Protection	Spring Security CSRF (enabled for state‑changing endpoints)	Already partially there, but needs full enforcement.
CORS Configuration	Spring @CrossOrigin or global config	Restrict which origins can call your API.
Rate Limiting per User / IP	Bucket4j, Resilience4j RateLimiter	Already have TokenBucket – upgrade to distributed rate limiting using Redis.
IP Whitelist / Blacklist	Custom filter	Block known malicious IPs (e.g., from admin panel).
HTTPS / TLS	Let’s Encrypt, Cloudflare	Encrypt all traffic.
Encryption at Rest	Database encryption (AES‑256) + secure key management	Protect sensitive user data.
Secret Management	HashiCorp Vault, AWS Secrets Manager, Kubernetes Secrets	Store database passwords, API keys, JWT secrets securely.
Audit Logs	Custom AuditService + separate database table	Track who accessed what resource (GDPR requirement).
Data Anonymization / Pseudonymization	Custom service	For research data exports, remove PII.
Vulnerability Scanning	OWASP Dependency‑Check, Snyk	Scan dependencies for known CVEs.

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📈 3. Observability & Monitoring

Component	Technology	Why Important
Structured Logging	Logback + JSON layout, Loki (Grafana)	Make logs machine‑parseable, centralise them.
Distributed Tracing	OpenTelemetry + Jaeger / Zipkin	Trace requests across multiple services (e.g., API → DB → AI service).
Metrics	Micrometer + Prometheus + Grafana	Monitor request latency, error rates, database pool usage, queue length.
Application Performance Monitoring (APM)	New Relic, Datadog, Elastic APM	Detect slow endpoints, SQL queries, external calls.
Health Checks	Spring Boot Actuator (/health, /info, /metrics)	Kubernetes liveness/readiness probes, load balancer health.
Alerts	Alertmanager (Prometheus), PagerDuty, Opsgenie	Get notified when CPU spikes, error rate rises, queue backs up.
Error Tracking	Sentry, Rollbar	Capture unhandled exceptions, aggregate by type, show stack traces.
Real User Monitoring (RUM)	Sentry, Datadog RUM	See how frontend performs for real users.
Synthetic Monitoring	Grafana Cloud, Pingdom	Periodically call critical endpoints to ensure uptime.

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⚙️ 4. Messaging & Async Processing

Component	Technology	Use Case
Task Queue	RabbitMQ, Kafka (with Spring AMQP / Kafka)	Indexing PDFs, sending emails, generating AI summaries, exporting large documents.
Dead Letter Queue	RabbitMQ DLX, Kafka with retry topics	Handle failed tasks gracefully.
Idempotency Keys	Custom header + Redis	Prevent duplicate message sending, duplicate payment processing.
Webhook Delivery	Custom WebhookService with retries + exponential backoff	Notify external systems (e.g., data repositories) about new publications.
Scheduled Jobs	Spring @Scheduled, Quartz	Daily digest emails, cleanup expired sessions, renew pre‑keys.
Batch Processing	Spring Batch	Process large CSV imports/exports in chunks.

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💾 5. Data & Caching

Component	Technology	When to Use
Read‑Through / Write‑Through Cache	Spring Cache abstraction + Redis	Cache frequently read data (user profiles, article metadata).
Query Cache	Hibernate Second‑Level Cache, Caffeine	Reduce SQL load for repeated queries.
Database Indexing	SQL CREATE INDEX	Speed up WHERE clauses, joins, sorting. Essential for large tables.
Partitioning / Sharding	PostgreSQL declarative partitioning, custom sharding	Split massive tables (e.g., messages) by date or user hash.
Read Replicas	Spring @Transactional(readOnly=true) + routing datasource	Offload analytic queries from master.
Full‑Text Search	Elasticsearch (sync via Change Data Capture)	Real‑time search across articles, messages, users.
Time‑Series Data	TimescaleDB (PostgreSQL extension)	Store and query article view events efficiently.
Data Archival	Custom job + cold storage (S3 Glacier)	Move old logs, deleted messages to cheap storage.

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🧪 6. Testing & CI/CD

Phase	Tools	Why
Unit Testing	JUnit 5, Mockito	Test business logic in isolation.
Integration Testing	Spring Boot Test, Testcontainers	Test with real database, RabbitMQ, Elasticsearch.
API Contract Testing	Pact	Ensure frontend and backend expectations match.
End‑to‑End Testing	Playwright, Cypress	Test critical user journeys (login, send message, publish article).
Load Testing	JMeter, Gatling, k6	Simulate thousands of users; find bottlenecks.
Security Testing	OWASP ZAP, Burp Suite	Scan for common vulnerabilities (XSS, SQLi).
CI/CD Pipeline	GitHub Actions, GitLab CI, Jenkins	Automatically build, test, and deploy on every commit.
Container Registry	Docker Hub, GitHub Container Registry, AWS ECR	Store Docker images.
Orchestration	Kubernetes (k8s)	Manage deployments, scaling, rolling updates.
Infrastructure as Code	Terraform, Pulumi, AWS CloudFormation	Define servers, databases, load balancers as code.
Blue‑Green / Canary Deployments	Kubernetes with Argo Rollouts, AWS CodeDeploy	Zero‑downtime releases, rollback capability.

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🧾 7. Business & Compliance

Component	Implementation	Purpose
GDPR / CCPA Compliance	Data deletion endpoint, consent management	Let users request deletion of their data.
Data Retention Policy	Scheduled job	Automatically delete old logs, deleted messages after 30/90 days.
Usage Billing	Stripe, Lago (open‑source)	If you ever charge for premium features.
Payment Webhooks	Custom endpoint	Handle subscription events, invoices.
Privacy Policy / Terms of Service	Static pages + acceptance tracking	Legal requirement.
Cookie Consent	Frontend library + backend consent flag	Comply with EU cookie law.
Data Export	GDPR export endpoint (JSON/CSV)	Users can download all their data.
Audit Logging	Separate table + API	Required for ISO 27001, SOC2 certification.

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🧩 8. Feature Flags & Experimentation

Component	Technology	Benefit
Feature Flags	LaunchDarkly, Flagsmith, custom (FeatureFlagService)	Enable/disable features without deployment.
A/B Testing	Custom assignment logic + metrics	Test new UI, recommendation algorithm variants.
Gradual Rollout	Flags + user percentage	Roll out a feature to 1% of users, then 10%, etc.

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🧠 9. Additional AI / ML Serving

Component	Implementation	Use
Model Serving	TensorFlow Serving, ONNX Runtime, BentoML	Serve recommendation model (GNN), classifier for smart notifications.
Feature Store	Feast (open‑source)	Manage features for ML models.
Model Monitoring	Evidently AI, WhyLogs	Detect data drift, model degradation.
Async Inference	Kafka + ML microservice	Process RAG queries, batch gap analysis offline.

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🌍 10. Localisation & Internationalisation (i18n)

Component	Implementation
Locale Detection	Accept-Language header, user preference in DB
Message Bundles	Spring MessageSource + .properties files
Date/Time Formatting	User’s timezone stored in profile, use ZonedDateTime
Right‑to‑Left (RTL) Support	Frontend CSS; backend doesn’t need much.

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📦 11. Production Environment Checklist

• Domain name with SSL certificate
• CDN for static assets (React build, uploaded images)
• WAF (Web Application Firewall) – Cloudflare, AWS WAF
• Database backups (automated, encrypted, stored off‑site)
• Disaster Recovery plan (RTO / RPO)
• Log rotation and retention policy
• Security headers (HSTS, CSP, X‑Frame‑Options)
• Rate limiting for critical endpoints (login, register, send message)
• IP whitelist for admin endpoints
• Regular security audits (dependency updates, penetration testing)
• Compliance documentation (if handling medical/student data)

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✅ Implementation Roadmap (What to Build First)

1. Caching – Redis for session store, rate limiting, and frequent queries.
2. Async Tasks – RabbitMQ for email sending, document indexing, PDF export.
3. Full‑Text Search – Elasticsearch for articles, messages, and users.
4. Observability – Prometheus + Grafana for metrics, Loki for logs.
5. Security Hardening – CSRF, rate limiting, JWT refresh tokens, HTTPS.
6. CI/CD – GitHub Actions to build, test, and deploy to staging.
7. Production Environment – Docker + Kubernetes on cloud (or self‑hosted).

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🎯 Final Advice

You don’t need to implement everything at once. Start with caching, async tasks, structured logging, and basic monitoring. Then add Elasticsearch, a message queue, and Kubernetes as you scale. For a research platform, compliance (GDPR) and data durability are top priorities.