Principle:Vespa engine Vespa Document Operation Reception
| Knowledge Sources | |
|---|---|
| Domains | Document_Processing, Indexing |
| Last Updated | 2026-02-09 00:00 GMT |
Overview
Document operation reception is the process of accepting incoming document lifecycle operations, classifying them by type, dispatching them to specialized handlers, and returning structured progress results.
Description
In any search engine or document store, the indexing pipeline must handle a variety of document operations: additions (puts), modifications (updates), and deletions (removes). Document operation reception is the entry point that receives a batch of these operations, iterates over them, and routes each one to the correct processing path based on its type.
The reception layer is responsible for several critical concerns:
- Type-based dispatch: Each document operation carries a distinct semantic meaning. A put operation creates or replaces a document, an update modifies specific fields of an existing document, and a remove deletes a document entirely. The reception logic must inspect the type of each operation and invoke the corresponding handler.
- Timeout management: Document processing may be subject to deadline constraints, particularly in high-throughput systems where operations are processed in batches. The reception layer calculates the remaining time budget and passes deadline information downstream so that long-running operations can be interrupted gracefully.
- Error classification: When processing fails, the nature of the failure determines the appropriate response. Input validation errors indicate malformed documents that should be rejected. Overload conditions signal that the system is temporarily at capacity and the operation should be retried later. Timeout errors mean the processing could not complete within the allowed time window.
- Batch atomicity: The reception layer processes all operations in a batch, collecting their outputs. Upon successful completion, the original operations are replaced with the processed results, ensuring that downstream consumers see only fully processed documents.
Usage
Document operation reception should be applied at the boundary between the document feeding infrastructure and the indexing pipeline. It is the first stage of processing after a document operation arrives from an external client or an internal reprocessing trigger.
Use this pattern when:
- You need a single entry point that handles all document lifecycle operations uniformly.
- You require structured error responses that distinguish between transient failures (overload, timeout) and permanent failures (invalid input).
- You want to enforce deadline-based processing to prevent any single batch from consuming unbounded time.
- You need to transform document operations in-place within a processing pipeline where the output replaces the input.
Theoretical Basis
The document operation reception pattern follows a command dispatch architecture. Each document operation is a command object that encapsulates an intent (put, update, remove) along with its payload. The reception layer acts as a dispatcher that inspects the command type and routes it to the appropriate handler.
The pseudocode for this pattern is:
function receiveOperations(batch):
if batch is empty:
return DONE
deadline = computeDeadline(batch.timeLeft)
results = []
for each operation in batch:
switch type(operation):
case PUT:
results.add(processPut(operation, deadline))
case UPDATE:
results.add(processUpdate(operation, deadline))
case REMOVE:
results.add(processRemove(operation))
default:
return INVALID_INPUT("unsupported type")
on InvalidInputException:
return INVALID_INPUT(reason)
on OverloadException:
return OVERLOAD(reason)
on TimeoutException:
return TIMEOUT(reason)
batch.replaceWith(results)
return DONE
The error classification follows the retry semantics pattern:
| Error Type | Retry Behavior | Upstream Action |
|---|---|---|
| Invalid Input | No retry | Reject the document |
| Overload | Retry with backoff | Slow down feeding rate |
| Timeout | Retry immediately | Resubmit the batch |
This separation of error types enables upstream systems to implement intelligent retry policies without needing to understand the internal details of the indexing pipeline.