Industry Segments - Segment Information (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Jan. 31, 2020	Jan. 31, 2019	Jan. 31, 2020	Jan. 31, 2019
Segment Reporting Information [Line Items]
Revenues	$ 30,600	$ 27,003	$ 86,193	$ 82,435
Operating income (loss)	2,819	2,130	4,459	4,263
Capital expenditures	101	120	339	1,014
Capitalized software	807	2,073	2,697	4,162
Depreciation and amortization	1,882	1,960	6,310	5,671
Earnings (loss) before income taxes	3,797	2,657	6,674	5,353
Supply Chain Management
Segment Reporting Information [Line Items]
Revenues	25,578	21,494	71,411	65,066
Operating income (loss)	6,693	4,981	14,904	12,021
Capital expenditures	43	21	117	145
Capitalized software	807	2,073	2,697	4,162
Depreciation and amortization	1,785	1,862	6,026	5,416
Earnings (loss) before income taxes	6,743	5,190	15,259	12,248
IT Consulting
Segment Reporting Information [Line Items]
Revenues	4,475	4,938	13,011	15,517
Operating income (loss)	43	244	210	999
Capital expenditures	0	0	0	1
Capitalized software	0	0	0	0
Depreciation and amortization	2	2	4	6
Earnings (loss) before income taxes	43	244	209	999
Other
Segment Reporting Information [Line Items]
Revenues	547	571	1,771	1,852
Operating income (loss)	(3,917)	(3,095)	(10,655)	(8,757)
Capital expenditures	58	99	222	868
Capitalized software	0	0	0	0
Depreciation and amortization	95	96	280	249
Earnings (loss) before income taxes	$ (2,989)	$ (2,777)	$ (8,794)	$ (7,894)