Redis Message Aggregator

Overview

The Redis Message Aggregator node collects and aggregates messages associated with a specific key (such as a user ID, group ID, or a combination) using Redis as a backend. It is designed to handle multiple triggers that send messages independently but need to be combined into a single aggregated output intelligently.

This node supports two main strategies for aggregation:

• Smart Wait: Waits until no new messages arrive within a specified timeout period before outputting the aggregated message.
• Immediate on Complete: Outputs the aggregated message immediately once it detects that the last message ends with one of the predefined "end words" indicating completion.

Practical Use Cases

• Combining chat messages from a user or group that arrive in parts into a single coherent message.
• Collecting sensor or event data over a short time window before processing.
• Aggregating fragmented notifications or logs before sending them downstream.

For example, if a chatbot receives multiple partial inputs from a user, this node can wait until the user finishes typing (detected by a pause or an end word) and then output the full combined message.

Properties

Output

The node outputs JSON objects describing the aggregation status and results. The structure varies depending on the strategy and state:

• status: Indicates the current state, e.g., "messages_aggregated", "message_stored", "timeout", "no_messages".
• key: The aggregation key used.
• aggregatedMessage: The combined message string (present when messages are aggregated).
• messageCount: Number of messages aggregated.
• originalMessages: Array of original message objects with content and timestamp.
• trigger: What caused the output, e.g., "immediate_complete", "smart_timeout".
• aggregatedAt: ISO timestamp when aggregation occurred.
• reason: Explanation for certain statuses like waiting or timeout.
• totalWaitTime: Total wait time in seconds (for smart wait).

If binary data were involved, it would be summarized here, but this node only handles textual JSON data.

Dependencies

• Requires a Redis server accessible via credentials configured in n8n.
• Needs an API key credential or connection details for Redis (host, port, password, TLS, etc.).
• Uses the ioredis library internally to interact with Redis.
• No other external services are required.

Troubleshooting

Common Issues

• Missing Redis Credentials: The node will throw an error if Redis credentials are not provided or invalid.
• Connection Failures: Network issues or incorrect Redis connection parameters can cause connection errors.
• Timeouts: If messages expire in Redis before aggregation completes, the node may output a "no_messages" or "timeout" status.
• Lock Contention: The node uses Redis locks to prevent concurrent aggregations; if locking fails repeatedly, aggregation might be delayed or skipped.

Error Messages

• "Không tìm thấy Redis credentials": Means Redis credentials are missing; ensure proper credentials are set up.
• Errors containing "READONLY" indicate Redis is in read-only mode; check Redis server status.
• Other errors include JSON parsing failures or Redis command errors; verify message content format and Redis health.

Resolution Tips

• Verify Redis credentials and connectivity.
• Adjust wait times according to message frequency.
• Ensure end words are correctly specified for immediate strategy.
• Monitor Redis server logs for operational issues.

Links and References

• Redis Official Documentation
• ioredis GitHub Repository
• n8n Documentation - Creating Custom Nodes
• Message Aggregation Patterns