Question

What would be best practice for the following situation. I have an ecommerce store that pulls down inventory levels from a distributor. Should the site, for everytime a user loads a product detail page use the third party API for the most up to date data? Or, should the site using third party APIs and then store that data for a certain amount of time in it’s own system and update it periodically?

To me it seems obvious that it should be updated everytime the product detail page is loaded but what about high traffic ecommerce stores? Are completely different solutions used for that case?

Answer 1

In this case I would definitely cache the results from the distributor’s site for some period of time, rather than hitting them every time you get a request. However, I would not simply use a blanket 5 minute or 30 minute timeout for all cache entries. Instead, I would use some heuristics. If possible, for instance if your application is written in a language like Python, you could attach a simple script to every product which implements the timeout.

This way, if it is an item that is requested infrequently, or one that has a large amount in stock, you could cache for a longer time.

if product.popularityrating > 8 or product.lastqtyinstock < 20:
   cache.expire(productnum)
distributor.checkstock(productnum)

This gives you flexibility that you can call on if you need it. Initially, you can set all the rules to something like:

 cache.expireover("3m",productnum)
 distributor.checkstock(productnum)

In actual fact, the script would probably not include the checkstock function call because that would be in the main app, but it is included here for context. If python seems too heavyweiaght to include just for this small amount of flexibilty, then have a look at TCL which was specifically designed for this type of job. Both can be embedded easily in C, C++, C# and Java applications.