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Asynchronous Report Generation Pattern

The Asynchronous Report Generation Pattern is a design approach used to handle computationally intensive or time-consuming report creation tasks without blocking the user interface or delaying API responses.^[001-TODO__code.md]

Core Workflow

The process begins when a client submits a request to generate a report, typically by providing search parameters and a desired export format (e.g., CSV or PDF).^[001-TODO__code.md] Instead of waiting for the report to finish, the system immediately returns an identifier (ID) for the report request.^[001-TODO__code.md]

This ID serves as a handle that allows the client to track the status of the report or retrieve the final document later, decoupling the request from the actual execution time.^[001-TODO__code.md]

State Management

The system maintains the state of the report generation process, usually tracking it through statuses such as RUNNING, SUCCESS, or FAIL.^[001-TODO__code.md]

A database record is created with these details, storing the search parameters and the current status.^[001-TODO__code.md] This ensures that the process is persistent and can be monitored or retried in case of failures.^[001-TODO__code.md]

Implementation Logic

Query Deduplication

To prevent redundant processing for identical requests made within a short time frame, the system may implement a deduplication check^[001-TODO__code.md]. This often involves creating a hash of the search parameters and checking the database for recent, successful, or running jobs with the same hash^[001-TODO__code.md].

Chunking and Merging

For large datasets, the report generation is often split into smaller, manageable chunks.^[001-TODO__code.md] The system may generate individual file segments (e.g., page 1, page 2) and store them temporarily.^[001-TODO__code.md] Once all segments are successfully created, a background process combines these segments into a single, final document^[001-TODO__code.md].

Failure Handling

Robust implementations include mechanisms to handle timeouts or errors during generation^[001-TODO__code.md]. If the process fails, the status is updated to FAIL, often with an accompanying error message, rather than leaving the request in a perpetual RUNNING state^[001-TODO__code.md].

Sources

^[001-TODO__code.md]