CodeBase is a high-speed xBASE compatible database engine for C/C++, Visual Basic, Delphi & Java programmers. You can use CodeBase to write high performance database applications that are multi-user compatible with FoxPro, dBASE and Clipper, create anything from a Java applet to a full-blown Windows database application to a simple DOS utility, write scalable applications that can be deployed as single-user, multi-user or client/server, all without changing any of your source code, and port your applications to Windows, DOS, UNIX, OS/2, and Macintosh. There's a free 30-Day Test Drive option available. CodeBase is available for every major operating system including Windows XP, 2000, 9x, NT, CE, DOS, OS/2, Macintosh, and a variety of Linux and UNIX platforms including Solaris, SunOS, HP/UX, AIX, SCO, and others.
Ice is a modern alternative to object middleware such as CORBA or COM/DCOM/COM+. It is easy to learn, yet provides a powerful network infrastructure for demanding technical applications. It features an object-oriented specification language, easy to use C++ and Java mappings, a highly efficient protocol (including protocol compression), asynchronous method invocation and dispatch, dynamic transport plug-ins, TCP/IP and UDP/IP support, SSL-based security, a firewall solution, and much more.
REALbasic is a cross-platform software development environment for developers who want to create and deliver native applications for Mac OS, Windows, and Linux. For example, you can create an application for Mac OS and Linux from a Windows machine. It is intended for people with all levels of programming experience. It is object-oriented, powerful, and supports advanced programming concepts like inheritance, polymorphism, interfaces, delegates, introspection, etc.
db4o is an object database for Java and all .NET environments. Its features include ACID transactions, automatic class schema recognition, query-by-example, a S.O.D.A. object querying API, native queries, LINQ support on .NET, callback methods, memory files, cascade-on-delete, multi-threaded access, and Java Webstart and servlet support.