Our Melbourne integration development follows a methodology designed for reliable, maintainable system connectivity: (1) Integration assessment (weeks 1-2): understanding the system landscape. System inventory: cataloguing all systems requiring integration — technology platform, API availability, data model, and current integration methods (if any). For each system: API assessment (REST? SOAP? GraphQL? No API?), authentication (OAuth, API key, basic auth?), rate limits (how many requests per second/minute?), data format (JSON, XML, CSV, proprietary?), and documentation quality (well-documented API vs. undocumented legacy system). Data flow mapping: defining what data needs to flow between which systems, in which direction, at what frequency, and with what business logic. Melbourne enterprise: typically revealing 20-40 data flows across the system landscape — some obvious (orders from eCommerce to ERP), some hidden (employee data changes needing to propagate to 8 systems). Integration pattern selection: for each data flow — real-time event-driven (system A triggers an event → integration processes immediately → system B updated within seconds. Best for: time-sensitive data — orders, inventory, and customer interactions), near-real-time polling (integration checking for changes every 1-5 minutes. Best for: data that needs to be current but not instant — CRM updates, pricing changes), batch (scheduled processing of accumulated data — hourly, daily, or weekly. Best for: large-volume data transfers, reporting data, and financial reconciliation), or request-response (system A requesting data from system B on demand. Best for: lookup operations — checking stock availability, verifying customer details). (2) Architecture and design (weeks 2-3): designing the integration solution. Integration architecture: choosing the right approach. Point-to-point (direct connections between systems — simple for 2-3 systems but creating a maintenance nightmare for 5+ systems. Each new system: requiring connections to every existing system. Melbourne enterprises: often starting with point-to-point and reaching a maintenance crisis at 8-12 connections), integration hub (centralised integration platform — all systems connect to the hub, which routes, transforms, and manages data flows. Scalable: adding a new system requires only connecting it to the hub. Our recommendation: for Melbourne enterprises with 4+ systems requiring integration), event-driven (publish-subscribe architecture — systems publishing events to a message broker, other systems subscribing to relevant events. Scalable and loosely coupled: systems don't need to know about each other. Best for: real-time, high-volume integrations), and iPaaS (integration Platform as a Service — cloud-based integration using platforms like Workato, Celigo, or Make. Good for: standard SaaS-to-SaaS integrations with available connectors. Limitation: custom business logic and legacy system integration often exceeding iPaaS capability). API design: for integrations requiring custom APIs — REST API design following OpenAPI specification. Versioning (API versions enabling backward-compatible evolution — existing integrations continuing to work when new features are added), error handling (clear error responses enabling consuming systems to handle failures gracefully — retry logic, dead letter queues, and human notification for unresolvable errors), and documentation (automated API documentation from OpenAPI spec — Swagger UI for developer reference). Data transformation: defining how data maps between systems. Schema mapping (field-by-field mapping between source and target systems — handling different field names, data types, and formats), business logic (transformation rules beyond simple mapping — calculating derived values, applying business rules, and enriching data), and validation (ensuring data quality during transformation — rejecting invalid data, logging warnings for unusual values, and applying default values for missing fields). (3) Development (weeks 3-6): building the integrations. Technology stack: Node.js (our default for Melbourne integration projects — excellent ecosystem for API connectivity, async processing, and data transformation), message broker (RabbitMQ or AWS SQS for event-driven integrations — reliable message delivery with retry and dead letter capability), and database (PostgreSQL for integration state management — tracking which records have been synchronised, storing transformation logs, and maintaining integration health data). Connector development: building connectors for each system. Well-documented APIs (Shopify, Salesforce, Xero — connectors built using official SDKs or API clients, leveraging existing OAuth flows and webhooks), poorly-documented APIs (legacy systems with minimal documentation — reverse-engineering API behaviour through testing, building robust error handling for undocumented error conditions), no API (legacy systems with no API — database-level integration (reading/writing directly to the database — with careful consideration of data integrity), file-based integration (CSV/XML file exchange — polling for new files, processing, and archiving), or screen scraping (automated UI interaction — used only as a last resort when no other option exists)). Error handling: robust error management. Retry logic (transient failures — network issues, rate limits, temporary unavailability — automatically retried with exponential backoff), dead letter queue (permanently failed items captured for manual review — not lost, not blocking other processing), alerting (failures notified to operations team — with context enabling rapid resolution), and reconciliation (periodic comparison of data between systems — identifying any items that fell through the cracks). (4) Testing (weeks 5-7): ensuring reliability. Integration testing: testing data flows end-to-end. Happy path (data flowing correctly through the integration — correct transformation, correct delivery, correct timing), error scenarios (what happens when a system is unavailable? When data is malformed? When rate limits are exceeded? Each error scenario: tested and verified to be handled gracefully), volume testing (testing at expected data volumes — 100 orders/day vs. Black Friday 5,000 orders/day. The integration: performing correctly under both normal and peak conditions), and edge cases (unusual data — special characters in names, very large orders, international addresses, and other unusual but possible data that might break the integration). Regression testing: automated tests running continuously — verifying that integrations continue to work as systems are updated. SaaS platforms updating frequently — an API change by Shopify or Xero could break an integration. Continuous testing: detecting breaks before they affect business operations. (5) Deployment and monitoring (weeks 6-8+): going live and maintaining. Deployment: staged rollout — testing with a subset of data before enabling full production flows. Monitoring: continuous integration health monitoring. Data flow monitoring (tracking data volumes, processing times, and success rates — dashboards showing integration health at a glance), error monitoring (real-time alerting for integration errors — classified by severity and impact), SLA monitoring (tracking whether data is flowing within defined time windows — orders synchronised within 5 minutes, financial data reconciled within 1 hour), and data quality monitoring (tracking data quality metrics — completeness, accuracy, and consistency between systems). Operations: ongoing integration maintenance. API version updates (when integrated systems release new API versions — testing and updating connectors), data model changes (when business requirements change — adding new data flows, modifying transformations), and performance optimisation (tuning integration performance as data volumes grow).