Use EventBridge to route events, OpenSearch to index and analyze them, and an API Gateway WebSocket API to deliver selected updates to browser clients. A backend such as Lambda connects those services: it validates and normalizes events, applies authorization and tenant filters, updates OpenSearch, and sends compact results to connected clients. EventBridge does not push OpenSearch data directly to a browser, and OpenSearch Dashboards is best kept for exploration and historical analysis rather than used as the live-update transport.
How the event-to-browser flow works
The services have separate roles. EventBridge matches events and invokes a target; OpenSearch stores and analyzes indexed data; API Gateway WebSockets maintain browser connections and let a backend send callbacks to clients. A controlled backend is where those roles are joined.
- Emit an event. An application or AWS service produces an event. EventBridge can also deliver near-real-time system events describing changes to OpenSearch Service domains, as AWS explains in Monitoring Amazon OpenSearch Service domains. Those domain-change events are not the same thing as a stream of every document indexed in OpenSearch.
- Match and route it. An EventBridge rule filters matching events and invokes a target such as Lambda, Kinesis, Step Functions, SNS, or SQS.
- Validate and process it. The backend checks the event, enforces authorization and tenant boundaries, and converts it into a normalized document or aggregate suitable for indexing.
- Update OpenSearch. The backend writes the data to OpenSearch. It can query OpenSearch when the browser needs a result based on current indexed data, rather than assuming an incoming event alone contains everything needed for the display.
- Send a small update to subscribers. The backend posts a compact metric delta or selected query result to the relevant connection IDs through the API Gateway Management API.
- Render the change. The browser updates its chart or status view. OpenSearch Dashboards remains available for users who need to explore broader datasets, run queries, or inspect historical trends.
A WebSocket API supports two-way communication between a client app and its backend, unlike a request-and-response REST API, according to AWS’s Overview of WebSocket APIs in API Gateway. In a dashboard, the browser can use that channel to subscribe, unsubscribe, or send other routed messages, while the backend uses the management API to send updates back.
What each service should—and should not—do
| Component | Useful responsibility | Boundary to keep in mind |
|---|---|---|
| OpenSearch or OpenSearch Service | Indexing, search, aggregations, and analysis of logs, metrics, and traces; OpenSearch Dashboards provides visualizations and dashboards. | It is the searchable analytics store, not the browser connection manager. |
| EventBridge | Event bus, event filtering, and target invocation. | It is not the low-latency browser transport or a durable time-series database. Its OpenSearch domain system events describe domain changes, not necessarily application-level data changes. |
| API Gateway WebSocket API | Persistent client connections, route selection, and callbacks to connected clients. | It does not perform the dashboard’s authorization, data shaping, or OpenSearch query logic for you. |
| Lambda or another backend | Normalization, authorization, tenant filtering, query execution, and fan-out. | It is an application layer you must design, secure, and operate; the three named services do not automatically provide a complete subscription and delivery system. |
| CloudWatch and CloudTrail | Operational metrics, alarms, and API-call history for the system. | Use them to observe and investigate the pipeline, not as substitutes for application-level event handling. |
Designing the WebSocket connection and fan-out
API Gateway provides the predefined $connect, $disconnect, and $default routes; you can add custom routes for messages such as subscriptions. AWS documents a maximum WebSocket connection lifetime of two hours and closure of idle connections after 10 minutes in its Overview of WebSocket APIs in API Gateway. Clients therefore need reconnect behavior, and the server needs a way to determine which active connections should receive each update.
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A connection registry, often implemented with DynamoDB, can associate connection IDs with users, tenants, or subscriptions. The registry, subscription filters, batching policy, retries, and stale-connection cleanup are design choices—not guarantees built into EventBridge, OpenSearch, or API Gateway. Keep the data sent over a callback small: a count change or chart delta often avoids repeatedly sending a full query result.
Authorize each connection and each data operation
- Authorize a client during
$connectwith IAM or a Lambda authorizer. - Repeat tenant and permission checks in backend subscription handling and every query. Connection-time authorization protects the session; it does not replace checks on the data requested later.
- Keep OpenSearch behind a restricted service layer rather than exposing unsigned public APIs. AWS’s OpenSearch tutorial recommends a controlled API/Lambda layer.
- Sign calls to the API Gateway Management API with SigV4 and grant the backend only the management actions it needs.
- Apply least-privilege data and network policies to OpenSearch access.
Handle disconnects, duplicates, and delivery failure
AWS says the $disconnect route runs after a connection closes, but delivery is best effort and is not guaranteed; see Manage connected users and client apps: $connect and $disconnect routes. Treat the registry as potentially stale. When a callback returns a gone-connection error, remove that connection ID. Make retries safe through idempotent processing, and define how the system handles duplicate events, out-of-order updates, backpressure, and a client that reconnects after missing messages.
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EventBridge and Lambda are asynchronous boundaries, so the architecture should specify its acceptable freshness and recovery behavior rather than promise instantaneous, exactly-once browser updates. Monitor ingest lag, query latency, callback failures, active connections, and authorization failures using CloudWatch metrics and alarms; use CloudTrail API-call history when investigating relevant actions.
Choose the OpenSearch deployment for the workload
Provisioned OpenSearch domains and OpenSearch Serverless differ in operational and scaling choices. The appropriate option depends on workload shape and requirements; the available evidence does not establish a universal cost or performance winner.
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| Decision axis | Provisioned OpenSearch domain | OpenSearch Serverless |
|---|---|---|
| Workload isolation | Assess how the domain’s workload and resource allocation fit the system’s isolation needs. | Assess how the serverless model fits the required workload isolation. |
| Indexing and search scaling | Plan scaling around the provisioned domain model. | Indexing and search compute are separated; account for this distinction in scaling and isolation decisions. |
| Storage model | Evaluate the domain’s storage and operational requirements for the workload. | Amazon S3 is primary index storage. |
| Network controls, cost model, and operational ownership | Compare the domain’s network controls, cost model, and ownership burden against your requirements. | Compare Serverless network controls, cost model, and ownership burden; do not assume they match a provisioned domain. |
| Feature compatibility | Verify required features against the domain offering you plan to use. | Verify required features against Serverless; compatibility should not be assumed to be identical. |
Choose polling or WebSockets based on freshness and operating cost
Polling is simpler when a page can tolerate checking periodically and there are few clients or updates. WebSockets suit a dashboard that needs server-initiated updates, but they add connection state, subscription management, reconnect handling, and server-side fan-out. Neither approach has a generally established freshness or cost advantage without workload-specific measurements.
| Consideration | Polling | WebSockets |
|---|---|---|
| Freshness | Updates arrive when the next poll runs; the interval determines how quickly a change can appear. | The server can send a selected update without waiting for the browser’s next poll. |
| Connection and state complexity | Uses repeated requests and does not require a persistent subscription connection. | Requires connection lifecycle management and usually a registry and subscription filters. |
| Browser recovery | The next successful request can retrieve current data after a temporary interruption. | The client must reconnect and may need to resubscribe or refresh state after a missed update. |
| Server work and fan-out | Repeated requests can trigger redundant queries, including when data has not changed. | Requires backend fan-out to the appropriate connected clients; batching and compact deltas can help manage that work. |
| Failure recovery | A later poll can recover current state, though it may not show intermediate changes. | Define retry, duplicate, ordering, and missed-message behavior; a reconnect can require a fresh query or snapshot. |
Use OpenSearch Dashboards or build a custom live client?
OpenSearch Dashboards is the natural place to create OpenSearch visualizations and explore historical data. A purpose-built dashboard is more appropriate when the page must combine sources, enforce application-specific tenant boundaries, or control exactly which live updates a user sees. The custom client can use WebSockets for a compact live view while retaining a link or workflow into OpenSearch Dashboards for deeper analysis. A custom interface gives more control, but you must own its authentication, authorization, connection handling, and update behavior.
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