Skip to main content

Backwards Compatibility Requirements

When your company upgrades a product, you and your product manager may concern yourselves with backwards compatibility.

Backwards compatibility refers to the extent to which the upgraded product works with existing ways of using the product. The upgrade may introduce new features and new ways of interacting with the product. But if a user can interact with the new version in the exact same manner and achieve the exact same results as with the old version, then it is fully backwards compatible.

However, backwards compatibility is not an end in itself. It avoids the following problems associated with existing users' lack of familiarity:
  • Relearning/retraining. To use a product that isn't backwards compatible efficiently, a user may undergo a punitive learning curve to get up to speed.
  • Mistakes. A user unfamiliar with the new interface may be more likely to make mistakes while using the product, causing possible physical, psychological, or monetary damage.
  • Fear of upgrading. Even if upgrading would be worth it from a cost/benefit perspective, users may be reluctant to buy or use the new version.
Your product manager should generally avoid making backwards compability a requirement. Instead, the requirements should include measurable constraints on the learning curve and the probability of destructive mistakes. The testing team should create and execute tests that ensure the upgrade meets these constraints before release.

Some degree of backwards compatibility will likely be a part of satisfying these requirements, but designers may find superior ways of satisfying them. For example, a designer may conceive of a new user interface that is so much simpler that it's easier to learn the new way of using the product than it is to use it the old way.

Armed with metrics showing that the learning curve and risk of destructive mistakes are minimal, your sales team has a powerful way of overcoming the fear of upgrading, regardless of whether the upgrade is backwards compatible.

Comments

Popular posts from this blog

Why Spreadsheets Suck for Prioritizing

The Goal As a company executive, you want confidence that your product team (which includes all the people, from all departments, responsible for product success) has a sound basis for deciding which items are on the product roadmap. You also want confidence the team is prioritizing the items in a smart way. What Should We Prioritize? The items the team prioritizes could be features, user stories, epics, market problems, themes, or experiments. Melissa Perri  makes an excellent case for a " problem roadmap ", and, in general, I recommend focusing on the latter types of items. However, the topic of what types of items you should prioritize - and in what situations - is interesting and important but beyond the scope of this blog entry. A Sad but Familiar Story If there is significant controversy about priorities, then almost inevitably, a product manager or other member of the team decides to put together The Spreadsheet. I've done it. Some of the mos

Use Case as a Black Box

Consider the following use case: Purchase Items Actor: Purchaser Precondition: Purchaser types at least thirty words per minute and has a web navigation efficiency rating of at least 40. Postcondition: For the average Purchaser acting at full efficiency, the number of seconds elapsed is no more than 30 + 20 * n, where n is the number of items purchased. The name of the use case represents a functional requirement. What does the product do, or enable the user to do? Purchase items. What are we to make of the preconditions and postconditions? What relationship do they have to the requirements for the product? Answer: the preconditions and postconditions are the nonfunctional requirements attached to the functional requirement . Another way of expressing the nonfunctional requirement would be as an attribute and associated constraint: Usability: For a Purchaser who types at least thirty words per minute and has a web navigation efficiency rating of at least 40, it shall take no

Henry Ford's "Faster Horse" Quote

You may have heard the ( apocryphal ) Henry Ford quote: If I'd asked customers what they wanted, they would have said "a faster horse". Over at the On Product Management blog , Saeed gives his take on this infamous quote. He "hates" it, and gives some compelling reasons. Saeed is spot on in his explanations. Personally, I think the quote is great, but it's a matter of interpretation. The valid point of the quote is not that it's a bad idea to facilitate a conversation with your market to better understand it. The valid points are: You must ask the right questions to get valuable answers. You must interpret the answers thoughtfully - often outside their direct meaning - to glean reliable information. Asking questions is not always the best way to "listen" to your market. (E.g., sometimes pure observational studies are more reliable.) Nonetheless, I find the quote is helpful to combat "armchair product management" in the