Following are notes on interfacing J with other applications.
J as Client
Excel and other spreadsheets.
Fortran subroutine access by creating a DLL.
Kdb+ database.
R statistical system, see R home page
Reading data out of Text Files.
Read and write NTFS File Streams.
J as Server
APL examples of calling J from APL.
Using J in Excel has examples of calling J from Excel.
A client/server Mac application has a Cocoa/Objective C client and a J server.
J dynamic library with Xcode to load in Mac OS X automatically without symbol assings
VBScript passing multidimensional arrays between VBScript and J
Jay Script J Language Active Script Connector
JX A C interface to J like K
MappingFilesBewteenCandJ mmap map means of sharing arrays between C and J
JFEX j.dll - A commentary on j602/system/examples/jfe/jfex.c
GTK
GTK to use GTK+ 2.0 as a GUI for J console
Java
Calling Java using Java Native Interface (JNI) directly from J
Java Native OpenGL to use Java and native OpenGL as GUI for J
.NET
.NET Interop, example of creating a re-usable cover framework with automatic type conversion, exception handling etc.
J with C#, step-by-step illustrated guide with Visual Studio examples for J601a
J with VB.NET, a guide on using J602a with Visual Studio .NET 2008 Express Edition
ADO.NET Array Adapter returns query result from any data provider in a generic way, represents results as boxed array and imports to J.
Web Services
SOAP Web Service exposing J component, consumed by .NET and Java
SOAP Call from J to the Web Service above
Mac SOAP Client consuming the web service with Mac clients and Automator