Being a big fan of file encapsulation (essentially centralizing business logic relating to a file), I've created a fair number of file encapsulated service programs. They use native I/O. Since the service program is a one-stop shop, the file is defined as Update/Add. This causes a couple issues:
1. File needs to be copied into a test library.
In our environment we don't have separate test and production environments. In fact, most testing references a client's production library. This has actually worked fine without consequence. We always run STRDBG UPDPROD(*NO) for testing. What this means is that any file that is encapsulated needs to be copied into a test library otherwise the service program won't open the file. This is a minor pain (however has on occasion caused issues in testing b/c a file had pre-existed in a test library and it wasn't updated).
2. Files opened for update don't block read.
One of our main files I really wanted encapsulated couldn't be because it's a transaction file with millions of records. No blocking on read loops hurts. A lot.
3. Using SQL bloats job log in test mode. Slows single-record access.
IBM has really been pushing using SQL to access data, so I thought this might be a good occasion to follow that path they've laid out. Doing so addresses issues #1 & #2 above. I've modified one of our file encapsulated service programs to use SQL. I think it works pretty slick. Although one not-so-slick aspect is the "chain." Presumably Closing an existing cursor, Preparing a cursor, Declaring the cursor, then Fetching the cursor is going to be a lot slower than a simple chain. I'm willing to live with that, although I'm getting some beef about over-complicating it. In addition, using SQL and running the program with STRDBG UPDPROD(*NO) balloons the job log. Maybe I shouldn't care about the size of the job log in test, although in one of my tests of 100,000 records (~80k chains), the job wrapped twice and then I killed it. In this situation I may be able to load the file into an array or something, but I know that won't always be the case. (I do realize this is only an issue in testing, but I can also foresee concerns about this slowing down testing since it's writing out to the job log so much.)
This had me wondering how other shops handle file encapsulation. I know my last job had a completely separate test environment. That's not likely going to happen here anytime soon.
We also don't have change management software. Files being encapsulated had made some of our file changes quite a bit easier.
Here is a sample of the code. If you have the time, I'd appreciate comments.
CustomCall Data Systems