Well, this has been an interesting little excursion. I really wanted to make sure that I tried to test the boundaries of the "Java-free" EGL/RPG architecture and as soon as I did, I ran into a little bump.
The problem is that you can't use a variable as the URL of the REST request. I don't understand the limitation and I haven't really asked about it yet, but the limitation is real for now. And because of that, you can't just pass your parameters as variables in the URL and then retrieve them with simple calls to QzhbCgiParse in your RPG-CGI program.
All is not lost. As it turns out, when you call a function in a REST service the parameters for the function are passed to the REST service as a JSON string. The JSON string is somewhat buried in the POST data and to make it even more challenging the data is in ASCII, but the parameters are more or less accessible, depending on how hard you're willing to look.
I'm going to take the time to write a simple procedure to extract the parameter string from the POST data. Then in order to make things simple I'll write a second procedure to treat the parameter string as a single string parameter (if that's not too confusing). It will assume that any REST function has only a single parameter of type string.
With that, I can then build comma delimited data in the Rich UI client and parse it in the RPG program using %scan. It's not quite as seamless or flexible as the magic Record-to-Data Structure conversion of EGL, but it will prove the point. Once that's done, though, I think it will be time for me to move to a true EGL Service implementation.
Anyway, that's what I'm working on. Hopefully I'll have it done in the next day or so. It's just a little bit of a speed bump.
Comments would be great. And if an IBMer happens along this and thinks I'm doing something completely bizarre, feel free to let me know...