Review: xBASE Products for Linux

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Some Linux aficionados would lke to run their DOS-based xBASE database under Linux. Robert Broughton examines two products that make this possible.
dBMAN

dBMAN functions primarily in interpretive mode, although it is possible to compile programs. (Compiling a program does not produce an executable binary; It produces a .run file, which still requires dBMAN to execute it.) When dBMAN starts up, a CMD: prompt appears at the top of the screen. At this point, you can type in ASSIST, which starts up a menu-driven interface similar to ones available with FoxPro or dBASE, but limited in comparison; dBMAN's ASSIST only allows one file to be open at a time, which in turn means that it is not possible to set up relations. It is possible to start up a simple program generator from ASSIST. Again, it has a single file limitation.

It is also possible to enter CREATE REPORT or MODIFY REPORT at the CMD: prompt. This will put you in dBMAN's report writer, which works very nicely. The report writer allows relations. I had a little bit of trouble getting it to write a report with lines wider than 80 columns, but I eventually got it to work.

dBMAN provides a function called PMENU() to create pull-down menus. PMENU doesn't have any mechanism for temporarily disabling a menu choice.

dBMAN handles windows differently from other xBASE products. Prior to defining a window, you call PUSHWIND() to push the current window onto a stack. (When a program is in its initial state, the entire screen is considered to be a window.) You then call WINDOW() to create the window. When you are finished with it, you call POPWIND(), which removes the window, and makes the previous window active.

dBMAN allows you to define only one hot key. You do so by invoking the ONKEY( ) function. This will have no effect until you execute the statement ON KEY statement. (statement will normally be DO hot-key-handler.)

The BROWSE Command has a long list of options. You can browse only certain fields, and you can specify the width of each field, and whether it is editable. The list of fields can include fields in other files, which is great if you have relationships set up.

dBMAN does not use either termcap or terminfo. Instead, it includes a file named dbmterm.dbm. It looks a lot like termcap. The first problem I had to solve after installing dBMAN was that there were no entries for either “xterm” or “console”.

I created one for color xterms without a whole lot of difficulty, and it is included in Listing 1.

dBMAN has no facility for executing functions written in C or assembler.

There were a couple of nasty bugs in the version of dBMAN I evaluated, which was 5.32. The main one was that procedure files simply didn't work if the procedure file was a .prg. If you compiled it into a .run file, it worked OK.

A Benchmark

I put together a simple benchmark program, which can be found in Listing 2.

The test file I used contained 33,830 records. I ran the benchmark with dBMAN (compiled and non-compiled), FlagShip, and FoxPro 2.0 under MS-DOS. The benchmark was done on a 66MHz 486 with a SCSI disk. Here are the results. At first glance, you might conclude that both dBMAN and FlagShip were blown out of the water by FoxPro. This would be unfair. FoxPro generally beats similar MS-DOS products in benchmarks, because FoxPro, by design, grabs all resources it can find. No well-behaved Linux program would do this. To put it another way, dBMAN and FlagShip would run a lot faster if they allocated most of the 16 megabytes of memory on my machine, but someone doing text editing on another terminal would see their performance suffer.

Compatibility

xBASE files always have separate data (.dbf) and index files. The format of data files is pretty much uniform for all xBASEs, but as far as I know, no two xBASE products use the same index file formats. I was able to use the same .dbf files with FlagShip and dBMAN, but I haven't tried any memo fields yet. (Memo fields put free-form text into a separate file, usually with the .dbt extension.)

Resources

Robert Broughton (a1040@mindlink.bc.ca) has been developing software for 23 years, and has been using Linux since February, 1993. He is employed by Zadall Systems Group, in Burnaby, BC, Canada.

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