Flutter and IBM as400

Question

a particular question: is there a direct way to make an AS400 connection or do you have to go through PHP? I don't have to read data on DB2, but do the various commands (wrkactjob, wrksyssts, etc.). Thank you.... sorry for the English. what I thought (maybe it can't be done) is this: in the app screen there are buttons, each button executes a command (wrkactjob, clroutq, etc.) and the answer occurs in another screen ... I didn't want to write commands directly like on 5250 or telnet

Answer 1

From your referral to typical "health checking" programs, like wrkactjob, and wrksyssts I guess your primary goal is to have an application running on your Android based phone to quickly check the status of a machine from wherever you are. Correct?

Have you considered how to get access to the machine's IP address when you're on the road and not connected to the local WiFi?

You can access this "performance data" through SQL — as John Y pointed out — and display it in whatever for is convenient on your mobile device. But I highly doubt Android provides ODBC infrastructure, even though you might manage to get the correct binary blobs (CPU wise) of the ODBC drivers from IBM botched into Android.

Otherwise you want to create a mechanism to scrape the screen for whatever is displayed, and translate that textual representation into UI elements provided by Flutter, if you want UI elements instead of textual output.

If you already have your doubts that you can't do telnet with Flutter, I think you'll have to learn a lot about Flutter as an SDK before even thinking about how to start developing an application. TCP/IP networking services are a function of the underlying OS and you'll have to go through all the Flutter abstraction layers to eventually be able to build a TCP session. With some luck, there is already code available to handle the telnet protocol peculiarities for you. Perhaps not, then you need to provide telnet negotiation and protocol yourself. This is documented in numerous RFCs. Use Google yourself.

Next point is: You need to establish translation routines for conversion of EBCDIC charset data into ASCII. Because Android is Linux based, you need to learn how to call libc routines like iconv() through Flutter, providing a C interface for charset conversion, including EBCDIC flavors as source/target.

Final point: You need to learn how to interpret the 5250 data stream, and translate the terminal emulator instructions into dynamically place Flutter UI elements at appropriate positions on screen. And of course you need to understand what to send back to IBM i to make it understand your request. The tn5250 data stream is also documented in publicly available RFCs.

There once was a facility called Workstation Gateway in the OS, but as I've found out, it has been removed in V5R2. This might have provided an easier means, because the 5250 data stream was converted on the fly to plain HTML.

Now it's your turn to decide if your goal is worth the apparent effort you're required to go through.

Answer 2

I am not sure what you mean by "direct". Do you mean doing your own socket programming? You could, but there are easier ways to connect.

The most obvious and straightforward choices are probably ODBC, JDBC, HTTP, and SSH.

ODBC and JDBC of course provide an SQL-based interface, and you can use that to issue commands (via the QCMDEXC procedure or scalar function) or access an increasingly comprehensive array of IBM i services.

If what you need still isn't available via SQL, or you simply don't like working in SQL, you could make use of the XMLSERVICE library, which provides its own programming interface "on top of" any of the connection types mentioned above. Despite all the instructions for building from source, normally this should already be installed on your IBM i. There are higher-level wrappers for XMLSERVICE in several programming languages (.NET, Node.js, PHP, Python, Ruby, and Swift), but as of this writing, not Dart. I am not familiar with Flutter, but I imagine you could use the JavaScript interop package to work with the Node.js wrapper.