Incoming OCPP message validation

SteVe performs two types of validation on incoming OCPP messages:

1. OCPP protocol validation checks requirements defined directly by the OCPP specification, such as required fields, string lengths, and valid data types. A violation immediately stops processing, and SteVe sends a generic OCPP error response. We started doing these validations since version 3.11.0.

2. Business and semantic validation checks whether a technically valid message is logically consistent and safe to process. This is the subject of this page. We started doing these validations since version 3.12.0.

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Business and semantic validation failures are classified as either soft or hard.

Severity	Meaning	General behavior
Soft	Suspicious input that can still be processed	Log a warning and continue
Hard	Input that prevents safe normal processing	Log an error and apply request-specific failure handling

Multiple validation errors from one request can be reported together. Soft errors do not stop processing unless the request also contains a hard error.

The source of truth is the implementation in CentralSystemService16_ServiceValidator, together with its caller, CentralSystemService16_Service.

Operational time tolerance

Timestamp comparisons use an operational tolerance to accommodate clock drift and small differences in sampling time.

The default tolerance is five minutes. A timestamp exactly at the five-minute tolerance boundary is accepted.

Validation rules

OCPP request	Validation condition	Severity	Processing outcome
StatusNotification	connectorId < 0	Hard	Log an error and return an empty StatusNotificationResponse. Do not persist the connector status, cancel reservations, or publish the status-update event.
StatusNotification	The optional timestamp is later than server time plus tolerance	Soft	Log a warning and continue normally.
SecurityEventNotification	Timestamp is later than server time plus tolerance	Soft	Log a warning and continue normally, including persistence of the security event.
StartTransaction	connectorId < 1	Hard	Log an error, but intentionally continue. Persist the transaction, publish the transaction-started event, and return a transaction ID.
StartTransaction	meterStart < 0	Hard	Log an error, but intentionally continue. Persist the transaction, publish the transaction-started event, and return a transaction ID.
StartTransaction	Timestamp is later than server time plus tolerance	Soft	Log a warning and continue normally.
StopTransaction	Referenced transaction cannot be found	Hard	Persist the stop in transaction_stop_failed; do not create a normal transaction stop or publish the transaction-ended event. Attached transaction data cannot be persisted without the transaction record.
StopTransaction	Transaction was already stopped by the station	Hard	Persist the stop in transaction_stop_failed, persist eligible attached meter data, and skip normal stop processing and event publication.
StopTransaction	Transaction start timestamp is after the stop timestamp	Hard	Persist the stop in transaction_stop_failed, persist eligible attached meter data, and skip normal stop processing and event publication.
StopTransaction	Stop timestamp is later than server time plus tolerance	Hard	Persist the stop in transaction_stop_failed, persist eligible attached meter data, and skip normal stop processing and event publication.
StopTransaction	meterStart > meterStop	Hard	Persist the stop in transaction_stop_failed, persist eligible attached meter data, and skip normal stop processing and event publication.
StopTransaction	A non-empty stop idTag differs from the transaction's start idTag and the two tags are not related through parentIdTag (i.e. one is not the parent of the other, or they do not have the same parent)	Hard	Persist the stop in transaction_stop_failed, persist eligible attached meter data, and skip normal stop processing and event publication.
MeterValues with a transaction reference	Referenced transaction cannot be found	Hard	Log an error, return an empty MeterValuesResponse, and do not persist the meter values.
MeterValues with a transaction reference	Referenced transaction was already stopped by the station	Hard	Log an error, return an empty MeterValuesResponse, and do not persist the meter values.
MeterValues	connectorId < 0	Hard	Log an error, return an empty MeterValuesResponse, and do not persist the meter values.
MeterValues or StopTransaction.transactionData	A non-null meter value has no timestamp	Hard	Apply the hard-error processing behavior of the enclosing request.
MeterValues or StopTransaction.transactionData	A non-empty collection contains no usable timestamp, for example because every entry is null	Hard	Apply the hard-error processing behavior of the enclosing request.
MeterValues or StopTransaction.transactionData	At least one meter-value timestamp is later than server time plus tolerance	Soft	Log a warning and continue normally.
StopTransaction.transactionData	At least one meter-value timestamp is later than the stop timestamp plus tolerance	Soft	Log a warning and continue normally.
Transaction-related MeterValues or StopTransaction.transactionData	At least one meter-value timestamp is earlier than the transaction start timestamp minus tolerance	Soft	Log a warning and continue normally.

Request-specific behavior

Request	Behavior when a hard error occurs
StatusNotification	Stop processing and return an empty response
MeterValues	Stop processing and do not persist the values
StartTransaction	Continue because SteVe must return a transaction ID
StopTransaction	Store the attempted stop in transaction_stop_failed; do not create a normal stop or publish the transaction-ended event