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The Validation Service provides the functionality required to determine if a ticket is valid at a specific time at a certain route. This is usually done through an app or different form of readers (validators) that can interpret BoB tickets or BoB IDs. or not. Validation is a check of the validity of a ticket in time and place. The result of a validation is either positive or negative. A positive validation result will confirm that the ticket is used at the right place, geography and/or vehicle type etc, at the right time. A negative validation result will indicate that the ticket is not valid for the place and/or time. A negative validation result can be handled in many ways depending on the business rules of the PTA/traffic company. Validation can be done by different devices such as bus validators, handheld units, gates or platform validators. A validation may also activate a ticket or payment procedure.
The Validation Service interprets the ticket information, first by ensuring that the electronic signature provided are authentic and created by a trusted party. The second step is to check the ticket's content to determine if it is valid on the current trip, or not. It compares the information contained within the ticket with corresponding information provided from the environment in which the validator operates in, typically a vehicle where it is being provided information regarding location, direction, zones and time (among other things). The checking presupposes that the ticket is designed in accordance with the Mobile Ticket Specifications. The Validation Service typically implements a parser for the TICKLE language (MTS6), and works in a semi-offline scenario. The greater part of the validation takes place locally in the validator, where it can be executed in a matter of a few milliseconds. After the local validation, a validation transaction are sent to the ticketing backend, where additional checks can be made, for example to detect double-spending across different vehicles and revoking such tickets. Such on-line transactions may however be too slow to always be completed over cellular networks in real-time as passengers are boarding. Therefore, these checks will be opportunistic, meaning if they can not complete within a certain time window (which may vary depending on several factors, such as traveller volume and ticket types) the validation checks will pass if local factors indicate a valid ticket.
Another variant of the Validation Service is the type of validator used for ticket inspections. Inspection is a check of the validity of a ticket. If the ticket is found to be invalid, a fine could be issued. Inspection is typically handled by dedicated staff that are apart from bus drivers or train hosts. As the Validation Service is used for inspecting tickets the requirements may be different. On-line fraud checks may have longer time-outs, and the transactions sent to the ticketing back-end are sent using a different interface (the inspection endpoint), and the transactions are registered as ticket inspection events rather than validation events.
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