What does this mean? Part I

In a meeting with colleagues I discovered that there was some slight confusion over the terminology used in multi-tenant systems. Therefore, I will give a short description of the differences between the terms which I regularly use and may cause confusion.

Multi-user vs single-user
A single-user application allows one user to use the application. Examples of this are most desktop applications, which allow customization (e.g. MS Word) for one user only. Multi-user applications allow multiple users to concurrently use the application, for example a system which would let you log in. An advantage of multi-user systems is that they do not require a new instance for each application user.

Multi-tenant vs single-tenant
In a single-tenant system, all users run their own application and database instance. In a multi-tenant system this instance is shared. I also refer to my introductory post on multi-tenancy.

Multi-tenant vs multi-user
Any system may have multiple users. In a multi-user system multiple users can use the application (e.g. Exact Synergy). The term multi-user does not imply anything for the architecture of the system. On the other hand, while a multi-tenant system is a multi-user system, multi-tenancy tells us something about the architecture of the system: namely that multiple users share the same application and database instance. Note that it is possible to have a multi-user system, which is not multi-tenant.

Web service vs business service
A business service is a service provided by a company, with which they (usually) make money. Examples are cooking lunch, offering a financial application and driving a cab. A web service is a method of accessing a specific application. Examples of a web service are generating a token, returning the server time and storing data in a database. The web service layer is implemented between the application and the user, and offers a user the possibility to easily integrate an application without deep knowledge of its architecture. For example, if I’d want to integrate eBay auctions into my application, I would use their web service to communicate with the eBay platform rather than finding out how their platform is implemented (also, they would probably not let me!).

If any other terms (or even this explanation!) confuse you, please let me know!