Some lightweight Databases

Embedded/lightweight databases are also useful.

There are three options.

1. db4o
Object-oriented lightweight database, supporting Java and. net, a little look at the class library, found. the "Java direction" of the Net version is very serious, so that the Library also contains a bunch of Java basic API encapsulation (namespace sharpen). In addition, there is a disadvantage that the encapsulation is not thorough enough, everything in the internal namespace is exposed. It is estimated that the main implementation is Java. the. NET version is only to modify the Java version and add Java compatibility.Code.
2. SQLite
Relational databases written in pure C are. NET and Java drivers. the. NET driver is fully compatible with ADO. net.
3. perst
Perst is an object-oriented lightweight database that supports Java and. net. I think its. Net API is well encapsulated and can be understood at almost a glance. It supports. NET 1.1 and 2.0. The default value is 1.1. to support 2.0, you need to add the compilation conditions use_generics during compilation.

The above database systems are all open-source. For specific protocols used, refer to their internal systems.
Other open-source databases