[tyingq]

Ah, a cobol browser plugin? Cool. And yeah, environments. It's like porting JS to the mainframe, but not providing the POSIX facade to allow it to make files, schedule batch jobs, kill processes, connect to the network, store data in a database, access rights, auth, etc.

[acdha]

Yes – AcuCOBOL had a COBOL development system which was byte-coded like Java (the technical founder had actually overlapped with Gosling in undergrad, I believe) so we already had the capability to copy the compiled program onto most platforms (Most Unix variants, VMS, Win16 and Win32, OS/2, DOS, OS/400, etc.) and launch it with the native runtime. There was also some ability to transparently redirect I/O — you could have any CALL which didn't wasn't in the local compiled code do an RPC call to a remote server, and redirect some or all ISAM operations to either a remote server or (with another license) a SQL database.

Once they had that infrastructure, it wasn't a huge amount of work to package the runtime as a plugin which was configured to enable the remote call & I/O options by default. Which is exactly restating your last point: having already done the hard 95% of the work, this part was straightforward.