{"id":3353,"date":"2026-08-27T11:31:11","date_gmt":"2026-08-27T09:31:11","guid":{"rendered":"https:\/\/www.5thfloor.be\/"},"modified":"2026-09-24T13:35:11","modified_gmt":"2026-09-24T11:35:11","slug":"legacy-applicatie-herschrijven-ai","status":"publish","type":"post","link":"https:\/\/www.5thfloor.be\/nl\/legacy-applicatie-herschrijven-ai\/","title":{"rendered":"AI-ondersteunde iso-functionele herschrijving"},"content":{"rendered":"<p class=\"wp-block-paragraph\"><strong>Welke applicaties in uw portfolio vormen het grootste risico, en welke kunnen nog even wachten?<\/strong><\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Zodra de diagnose is gesteld, moet je actie ondernemen met betrekking tot het punt dat bovenaan de lijst staat. AI-ondersteund iso-functioneel herschrijven is deze stap.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\"><strong>Waarom mislukken zoveel herschrijvingen<\/strong>?<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>Iso-functionele herschrijving <\/strong>bouwt de applicatie opnieuw op met identiek waarneembaar gedrag (dezelfde schermen, dezelfde berekeningen, dezelfde regels, inclusief randgevallen), terwijl de interne structuur volledig opnieuw wordt ontworpen. De modernisering volgt daarna, op een basis die dit daadwerkelijk mogelijk maakt omdat de techniek volledig onder de knie is.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\"><strong>De rol van AI, en waarom uw teams centraal blijven staan<\/strong><\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">Om een gedrag vast te leggen, moet u weten wat het systeem vandaag de dag doet, en die informatie bestaat nergens in geschreven vorm. <strong>Een oud systeem bevat kennis die ontbreekt in de documentatie<\/strong>: regels die nooit zijn vastgelegd, speciale gevallen die in de loop van hervormingen zijn toegevoegd, en workarounds die zijn ingevoerd om aan een re\u00eble behoefte in de praktijk te voldoen.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>AI komt precies daar in beeld<\/strong>. Het leest het oude in plaats van het nieuwe te ontwerpen. <strong>Het doorzoekt de broncode, haalt daaruit de regels die daadwerkelijk worden toegepast en zet deze om in een vorm die uw analisten kunnen lezen, onderzoeken en corrigeren<\/strong>. Dit is wat onze oplossing al doet in uw gehele codebase, en wat hier wordt toegepast op de applicatie die u aan het herschrijven bent. <\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><strong><a href=\"https:\/\/www.5thfloor.be\/wp-content\/uploads\/2026\/09\/5thfloor_white_paper_AI_swarm_iso_functional_rewrite_EN.pdf\" target=\"_blank\" rel=\"noreferrer noopener\">Het whitepaper downloaden<\/a><\/strong><\/p>\n\n\n\n<div class=\"wp-block-uagb-image uagb-block-1ecbc856 wp-block-uagb-image--layout-default wp-block-uagb-image--effect-static wp-block-uagb-image--align-none\"><figure class=\"wp-block-uagb-image__figure\"><a class href=\"https:\/\/www.5thfloor.be\/wp-content\/uploads\/2026\/09\/5thfloor_white_paper_AI_swarm_iso_functional_rewrite_EN.pdf\" target=\"_blank\" rel=\"noreferrer noopener\"><noscript><img decoding=\"async\" src=\"https:\/\/www.5thfloor.be\/wp-content\/uploads\/2026\/08\/5th-floor-whitepaper-isofunctionnal-rewrite-1024x909.png\" alt class=\"uag-image-3357\" width=\"1118\" height=\"992\" title=\"5th-floor-whitepaper-isofunctionnal-rewrite\" loading=\"lazy\" role=\"img\"><\/noscript><img decoding=\"async\" src=\"data:image\/svg+xml,%3Csvg%20xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F2000%2Fsvg%22%20viewBox%3D%220%200%201118%20992%22%3E%3C%2Fsvg%3E\" alt class=\"uag-image-3357 lazyload\" width=\"1118\" height=\"992\" title=\"5th-floor-whitepaper-isofunctionnal-rewrite\" loading=\"lazy\" role=\"img\" data-src=\"https:\/\/www.5thfloor.be\/wp-content\/uploads\/2026\/08\/5th-floor-whitepaper-isofunctionnal-rewrite-1024x909.png\"><\/a><\/figure><\/div>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\">\n\n\n\n<div class=\"wp-block-uagb-advanced-heading uagb-block-3da65d22\"><h2 class=\"uagb-heading-text\">FAQ<\/h2><\/div>\n\n\n<div class=\"wp-block-uagb-faq uagb-faq__outer-wrap uagb-block-9853f0c4 uagb-faq-icon-row uagb-faq-layout-accordion uagb-faq-expand-first-true uagb-faq-inactive-other-true uagb-faq__wrap uagb-buttons-layout-wrap uagb-faq-equal-height\" data-faqtoggle=\"true\" role=\"tablist\"><div class=\"wp-block-uagb-faq-child uagb-faq-child__outer-wrap uagb-faq-item uagb-block-2a95f4d8\" role=\"tab\" tabindex=\"0\"><div class=\"uagb-faq-questions-button uagb-faq-questions\">\t\t\t<span class=\"uagb-icon uagb-faq-icon-wrap\">\n\t\t\t\t\t\t\t\t<svg viewbox=\"0 0 448 512\"><path d=\"M432 256c0 17.69-14.33 32.01-32 32.01H256v144c0 17.69-14.33 31.99-32 31.99s-32-14.3-32-31.99v-144H48c-17.67 0-32-14.32-32-32.01s14.33-31.99 32-31.99H192v-144c0-17.69 14.33-32.01 32-32.01s32 14.32 32 32.01v144h144C417.7 224 432 238.3 432 256z\" \/><\/svg>\n\t\t\t\t\t\t\t<\/span>\n\t\t\t\t\t\t<span class=\"uagb-icon-active uagb-faq-icon-wrap\">\n\t\t\t\t\t\t\t\t<svg viewbox=\"0 0 448 512\"><path d=\"M400 288h-352c-17.69 0-32-14.32-32-32.01s14.31-31.99 32-31.99h352c17.69 0 32 14.3 32 31.99S417.7 288 400 288z\" \/><\/svg>\n\t\t\t\t\t\t\t<\/span>\n\t\t\t<span class=\"uagb-question\">Waarin verschilt dit van een geautomatiseerde codeconversie?<\/span><\/div><div class=\"uagb-faq-content\"><p>Een conversie vertaalt de ene taal naar de andere met behoud van de oorspronkelijke structuur. Het resultaat is nieuw en blijft moeilijk te onderhouden. Een herschrijving behoudt het gedrag en bouwt de structuur opnieuw op, wat inhoudt dat er samen met u architecturale beslissingen worden genomen.<\/p><\/div><\/div><div class=\"wp-block-uagb-faq-child uagb-faq-child__outer-wrap uagb-faq-item uagb-block-83363705\" role=\"tab\" tabindex=\"0\"><div class=\"uagb-faq-questions-button uagb-faq-questions\">\t\t\t<span class=\"uagb-icon uagb-faq-icon-wrap\">\n\t\t\t\t\t\t\t\t<svg viewbox=\"0 0 448 512\"><path d=\"M432 256c0 17.69-14.33 32.01-32 32.01H256v144c0 17.69-14.33 31.99-32 31.99s-32-14.3-32-31.99v-144H48c-17.67 0-32-14.32-32-32.01s14.33-31.99 32-31.99H192v-144c0-17.69 14.33-32.01 32-32.01s32 14.32 32 32.01v144h144C417.7 224 432 238.3 432 256z\" \/><\/svg>\n\t\t\t\t\t\t\t<\/span>\n\t\t\t\t\t\t<span class=\"uagb-icon-active uagb-faq-icon-wrap\">\n\t\t\t\t\t\t\t\t<svg viewbox=\"0 0 448 512\"><path d=\"M400 288h-352c-17.69 0-32-14.32-32-32.01s14.31-31.99 32-31.99h352c17.69 0 32 14.3 32 31.99S417.7 288 400 288z\" \/><\/svg>\n\t\t\t\t\t\t\t<\/span>\n\t\t\t<span class=\"uagb-question\">Wat is het verschil met een migratie of een herontwerp?<\/span><\/div><div class=\"uagb-faq-content\"><p>Bij een migratie wordt de infrastructuur gewijzigd zonder de bedrijfscode aan te raken. Bij een iso-functionele herschrijving wordt de technologie gewijzigd met behoud van het gedrag. Bij een herontwerp wordt het gedrag gewijzigd, en daarmee ook het bedrijfsproces en het bijbehorende regelgevingskader.<\/p><\/div><\/div><div class=\"wp-block-uagb-faq-child uagb-faq-child__outer-wrap uagb-faq-item uagb-block-83363705\" role=\"tab\" tabindex=\"0\"><div class=\"uagb-faq-questions-button uagb-faq-questions\">\t\t\t<span class=\"uagb-icon uagb-faq-icon-wrap\">\n\t\t\t\t\t\t\t\t<svg viewbox=\"0 0 448 512\"><path d=\"M432 256c0 17.69-14.33 32.01-32 32.01H256v144c0 17.69-14.33 31.99-32 31.99s-32-14.3-32-31.99v-144H48c-17.67 0-32-14.32-32-32.01s14.33-31.99 32-31.99H192v-144c0-17.69 14.33-32.01 32-32.01s32 14.32 32 32.01v144h144C417.7 224 432 238.3 432 256z\" \/><\/svg>\n\t\t\t\t\t\t\t<\/span>\n\t\t\t\t\t\t<span class=\"uagb-icon-active uagb-faq-icon-wrap\">\n\t\t\t\t\t\t\t\t<svg viewbox=\"0 0 448 512\"><path d=\"M400 288h-352c-17.69 0-32-14.32-32-32.01s14.31-31.99 32-31.99h352c17.69 0 32 14.3 32 31.99S417.7 288 400 288z\" \/><\/svg>\n\t\t\t\t\t\t\t<\/span>\n\t\t\t<span class=\"uagb-question\">Schrijft de AI de code helemaal zelf?<\/span><\/div><div class=\"uagb-faq-content\"><p>Nee. De AI produceert een eerste versie, zowel op basis van het lezen van de bestaande code als door zelf code te genereren. Uw teams valideren het verkregen gedrag ten opzichte van het verwachte gedrag. We documenteren dit mechanisme in detail in ons experimentrapport.<\/p><\/div><\/div><div class=\"wp-block-uagb-faq-child uagb-faq-child__outer-wrap uagb-faq-item uagb-block-83363705\" role=\"tab\" tabindex=\"0\"><div class=\"uagb-faq-questions-button uagb-faq-questions\">\t\t\t<span class=\"uagb-icon uagb-faq-icon-wrap\">\n\t\t\t\t\t\t\t\t<svg viewbox=\"0 0 448 512\"><path d=\"M432 256c0 17.69-14.33 32.01-32 32.01H256v144c0 17.69-14.33 31.99-32 31.99s-32-14.3-32-31.99v-144H48c-17.67 0-32-14.32-32-32.01s14.33-31.99 32-31.99H192v-144c0-17.69 14.33-32.01 32-32.01s32 14.32 32 32.01v144h144C417.7 224 432 238.3 432 256z\" \/><\/svg>\n\t\t\t\t\t\t\t<\/span>\n\t\t\t\t\t\t<span class=\"uagb-icon-active uagb-faq-icon-wrap\">\n\t\t\t\t\t\t\t\t<svg viewbox=\"0 0 448 512\"><path d=\"M400 288h-352c-17.69 0-32-14.32-32-32.01s14.31-31.99 32-31.99h352c17.69 0 32 14.3 32 31.99S417.7 288 400 288z\" \/><\/svg>\n\t\t\t\t\t\t\t<\/span>\n\t\t\t<span class=\"uagb-question\">Wie is eigenaar van de geproduceerde code?<\/span><\/div><div class=\"uagb-faq-content\"><p>U. Dit punt wordt contractueel vastgelegd vanaf de eerste offerte, samen met de kwestie van de opslaglocatie van de broncode tijdens de werkzaamheden.<\/p><\/div><\/div><div class=\"wp-block-uagb-faq-child uagb-faq-child__outer-wrap uagb-faq-item uagb-block-83363705\" role=\"tab\" tabindex=\"0\"><div class=\"uagb-faq-questions-button uagb-faq-questions\">\t\t\t<span class=\"uagb-icon uagb-faq-icon-wrap\">\n\t\t\t\t\t\t\t\t<svg viewbox=\"0 0 448 512\"><path d=\"M432 256c0 17.69-14.33 32.01-32 32.01H256v144c0 17.69-14.33 31.99-32 31.99s-32-14.3-32-31.99v-144H48c-17.67 0-32-14.32-32-32.01s14.33-31.99 32-31.99H192v-144c0-17.69 14.33-32.01 32-32.01s32 14.32 32 32.01v144h144C417.7 224 432 238.3 432 256z\" \/><\/svg>\n\t\t\t\t\t\t\t<\/span>\n\t\t\t\t\t\t<span class=\"uagb-icon-active uagb-faq-icon-wrap\">\n\t\t\t\t\t\t\t\t<svg viewbox=\"0 0 448 512\"><path d=\"M400 288h-352c-17.69 0-32-14.32-32-32.01s14.31-31.99 32-31.99h352c17.69 0 32 14.3 32 31.99S417.7 288 400 288z\" \/><\/svg>\n\t\t\t\t\t\t\t<\/span>\n\t\t\t<span class=\"uagb-question\">Geldt dit alleen voor COBOL?<\/span><\/div><div class=\"uagb-faq-content\"><p>Nee. De moeilijkheid komt voort uit het ontbreken van specificaties en uit de koppeling, niet uit de taal zelf. Een tien jaar oude, slecht gedocumenteerde applicatie levert hetzelfde probleem op.<\/p><\/div><\/div><\/div>","protected":false},"excerpt":{"rendered":"<p>Which applications in your portfolio pose the greatest risk, and which ones can wait? Once the diagnosis is made, you need to take action on the one at the top of the list. AI-assisted iso-functional rewriting is this step. Why do so many rewrites fail? Iso-functional rewriting rebuilds the application with identical observable behavior (same [&hellip;]<\/p>\n","protected":false},"author":9,"featured_media":3356,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"inline_featured_image":false,"_uag_custom_page_level_css":"","_post_is_featured":"","_post_subtitle":"","_post_team_members":[],"_post_wp_authors":[9],"_post_external_authors":[],"footnotes":""},"categories":[49],"tags":[],"class_list":["post-3353","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-projects"],"yoast_head":"<!-- This site is optimized with the Yoast SEO plugin v28.6 - https:\/\/yoast.com\/product\/yoast-seo-wordpress\/ -->\n<title>AI-Assisted Iso-Functional Rewriting of Legacy Systems<\/title>\n<meta name=\"description\" content=\"Iso-functional rewriting rebuilds a critical legacy application with identical behavior. AI reads the existing code, your teams validate every rule.\" \/>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/www.5thfloor.be\/nl\/legacy-applicatie-herschrijven-ai\/\" \/>\n<meta property=\"og:locale\" content=\"nl_NL\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"AI-Assisted Iso-Functional Rewriting of Legacy Systems\" \/>\n<meta property=\"og:description\" content=\"Iso-functional rewriting rebuilds a critical legacy application with identical behavior. AI reads the existing code, your teams validate every rule.\" \/>\n<meta property=\"og:url\" content=\"https:\/\/www.5thfloor.be\/nl\/legacy-applicatie-herschrijven-ai\/\" \/>\n<meta property=\"og:site_name\" content=\"5th floor\" \/>\n<meta property=\"article:published_time\" content=\"2026-08-27T09:31:11+00:00\" \/>\n<meta property=\"article:modified_time\" content=\"2026-09-24T11:35:11+00:00\" \/>\n<meta property=\"og:image\" content=\"https:\/\/www.5thfloor.be\/wp-content\/uploads\/2026\/08\/iso-functional-rewrite-application-it.jpg\" \/>\n\t<meta property=\"og:image:width\" content=\"1280\" \/>\n\t<meta property=\"og:image:height\" content=\"1920\" \/>\n\t<meta property=\"og:image:type\" content=\"image\/jpeg\" \/>\n<meta name=\"author\" content=\"Gilles Stragier\" \/>\n<meta name=\"twitter:card\" content=\"summary_large_image\" \/>\n<meta name=\"twitter:label1\" content=\"Written by\" \/>\n\t<meta name=\"twitter:data1\" content=\"Gilles Stragier\" \/>\n\t<meta name=\"twitter:label2\" content=\"Est. reading time\" \/>\n\t<meta name=\"twitter:data2\" content=\"2 minutes\" \/>\n<script type=\"application\/ld+json\" class=\"yoast-schema-graph\">{\"@context\":\"https:\\\/\\\/schema.org\",\"@graph\":[{\"@type\":\"Article\",\"@id\":\"https:\\\/\\\/www.5thfloor.be\\\/ai-legacy-application-rewrite\\\/#article\",\"isPartOf\":{\"@id\":\"https:\\\/\\\/www.5thfloor.be\\\/ai-legacy-application-rewrite\\\/\"},\"author\":{\"name\":\"Gilles Stragier\",\"@id\":\"https:\\\/\\\/www.5thfloor.be\\\/#\\\/schema\\\/person\\\/d86d41955340da69d18bfa0487edc373\"},\"headline\":\"AI-Assisted Iso-functional Rewriting\",\"datePublished\":\"2026-08-27T09:31:11+00:00\",\"dateModified\":\"2026-09-24T11:35:11+00:00\",\"mainEntityOfPage\":{\"@id\":\"https:\\\/\\\/www.5thfloor.be\\\/ai-legacy-application-rewrite\\\/\"},\"wordCount\":223,\"publisher\":{\"@id\":\"https:\\\/\\\/www.5thfloor.be\\\/#organization\"},\"image\":{\"@id\":\"https:\\\/\\\/www.5thfloor.be\\\/ai-legacy-application-rewrite\\\/#primaryimage\"},\"thumbnailUrl\":\"https:\\\/\\\/www.5thfloor.be\\\/wp-content\\\/uploads\\\/2026\\\/08\\\/iso-functional-rewrite-application-it.jpg\",\"articleSection\":[\"Projects\"],\"inLanguage\":\"nl-NL\"},{\"@type\":\"WebPage\",\"@id\":\"https:\\\/\\\/www.5thfloor.be\\\/ai-legacy-application-rewrite\\\/\",\"url\":\"https:\\\/\\\/www.5thfloor.be\\\/ai-legacy-application-rewrite\\\/\",\"name\":\"AI-Assisted Iso-Functional Rewriting of Legacy Systems\",\"isPartOf\":{\"@id\":\"https:\\\/\\\/www.5thfloor.be\\\/#website\"},\"primaryImageOfPage\":{\"@id\":\"https:\\\/\\\/www.5thfloor.be\\\/ai-legacy-application-rewrite\\\/#primaryimage\"},\"image\":{\"@id\":\"https:\\\/\\\/www.5thfloor.be\\\/ai-legacy-application-rewrite\\\/#primaryimage\"},\"thumbnailUrl\":\"https:\\\/\\\/www.5thfloor.be\\\/wp-content\\\/uploads\\\/2026\\\/08\\\/iso-functional-rewrite-application-it.jpg\",\"datePublished\":\"2026-08-27T09:31:11+00:00\",\"dateModified\":\"2026-09-24T11:35:11+00:00\",\"description\":\"Iso-functional rewriting rebuilds a critical legacy application with identical behavior. 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