The significance of "I"

Architecture
1

What is the general meaning and significance of the capital “i”, “I”, eye, in many class names?
(This font is really not helping state this question.)

IEventService
ICompositeExtensibleService
IDataChangeEventWriter
IDataChangeEventReader
IDataChaneEventManager
IDataChangeListener
IUnprocessedDataChangeEventHan
IRestConfig
IServiceConfig
com.leidos.leaf.beans.query.filter.booIean (That is a capital “i”, not an a lower case “L”)

2

This is a naming convention while not required is fairly common. An “I” preceding a name indicates that it is an interface rather than a concrete implementation. An example of this convention can be seen here Names of Classes, Structs, and Interfaces - Framework Design Guidelines | Microsoft Docs. LEAF consistently uses this convention to help quickly identify definition of a service from concrete implementations.

So for example the interface IEventService defines the functionality that all implementations of an event service should provide. There are a couple of concrete implementations, EventServiceKafka and EventServiceLocal, which are implementation specific and can be used anywhere an IEventService is required.

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3

Thanks.
And the last entry in the list, booIean?

4

I didn’t notice that comment, that looks like a typo to me. I will contact the team to see if it can be fixed.

Thanks

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