Monitoring systems are invisible, yet crucial. They help find out if there is a problem, and also help pin down the source of a failure so it can be fixed. Ideally, all of the boxes from the introductory post should have some point at which they can be monitored, both on input and output interfaces. In this post, I will briefly introduce the concepts in monitoring and explain why AVL systems, whether turn-key or custom-built, should have a monitoring component, and why that component should be evolve after delivery.
The four core concepts of monitoring systems are metrics, checks, alerts, and alarms.
Continue reading “AVL: Monitoring”
If you’ve done your homework on systems and how they hook up to the Internet, you have encountered the term API. APIs (Application Programming Interfaces) are defined methods for applications to talk to each other. All web users use them daily without knowing; if you load Google Maps or any Webmail page, your computer is first downloading a program that runs in your browser and that program is making ‘calls’ to an API to fill your screen with information. Many, though not all, AVL vendors include APIs with their system for data to be used in novel applications.
That is all well and good, but it might surprise some purchasers of AVL systems that they do not own the rights to data from their own vehicles. Like airline fares, some vendors un-bundle data ownership and the license to re-use it from their standard product, requiring extra payment to get access. This makes any additional applications or analysis very difficult. You shouldn’t let this happen, and many of us in the field are adamant. Further legal opinion on the topic can be found in TCRP Legal Digest 37, which notes that:
Although real-time data as such are not copyrightable, the majority view seems to be that a license or other agreement with provisions restricting access to or use or dissemination of data are not preempted by the Copyright Act. The rationale is that contracts affect the rights of the parties to the contract and do not involve exclusive rights against the world as exist under the copyright laws.
Legal digest 37 also contains sample contractual language to make data ownership clear. Ideally, this would be included in procurement documents.
Now that this is out of the way, I’d like to introduce Sean Barbeau’s presentation from APTA TransitTech 2013, which provides a very good introduction to APIs in the real-time transit context.