Composable ERP Is a Discipline, Not a Product

The Term Everyone Is Using

If you have sat through an ERP presentation in the past year, you have probably heard the word composable. Analysts at Gartner have promoted the idea of composable ERP for several years, and vendors have adopted the language enthusiastically. SAP has paired it with a phrase of its own, clean core, which it uses to describe keeping the central ERP as close to standard as possible and moving custom functionality out to a separate platform.

The terms are new. The problem they address is not. Most mid-market manufacturers running an ERP that is ten or fifteen years old know the problem well, because they live with it every time they try to upgrade.

How the Core Gets Dirty

ERP systems are bought to standardize processes, and then they are customized to fit the business.

ERP systems are bought to standardize processes, and then they are customized to fit the business. Some of that customization is necessary. Manufacturers have real differences in how they quote, schedule, cost and ship, and those differences are often part of what makes them competitive.

The trouble starts when the customization goes into the core of the system itself. Modified standard programs, custom fields added to core tables, database triggers, reports that read directly from internal structures. Each change made sense at the time. Together they create a system that cannot be upgraded without a project to find, test and rewrite every modification. The upgrade gets postponed, the system falls further behind, and the company ends up running an old version that the vendor eventually stops supporting.

What Composable Actually Means

Strip away the marketing and composable ERP is a design principle. The core ERP handles the standard transactions that every manufacturer performs in broadly the same way: general ledger, purchasing, inventory, order management, basic production. It is kept as close to the vendor's standard as possible, so that it can be upgraded without drama.

Everything that makes your business distinctive is built around the core rather than inside it. A specialized quoting tool, a scheduling application tuned to your constraints, a customer portal, a shop floor data collection app, an analytics layer. These connect to the ERP through its published interfaces, not by modifying its internals. When the ERP is upgraded, the interfaces stay stable and the surrounding applications keep working.

The Discipline It Requires

This is where the vendor pitch and reality diverge. You cannot buy composability. You can buy a platform that makes it easier, but the discipline that makes it work belongs to you.

It starts with a rule: no modifications to the core without a formal decision that there is no alternative. Every request for a change is first answered with the question of whether the standard system can do it with configuration, or whether it can be built outside the core.

It continues with an inventory of the customizations you already have. For each one, decide whether it is still needed, whether the current standard product now does it, whether it can be moved outside the core, or whether it genuinely has to stay. A review like this often turns up modifications that are no longer used, or that the current standard product now covers.

And it depends on integration done properly. Applications built around the core must use stable, documented interfaces. An extension that reads directly from internal tables is still a modification, just one that lives in a different place.

When It Makes Sense, and When It Does Not

Composable design pays off when a manufacturer has genuinely differentiating processes that the standard ERP cannot support, and the capability to build and maintain applications around it, whether in-house or through a partner. It also pays off for companies that want to stay current with their vendor's releases.

It is a poor fit for a company that wants one vendor to provide everything and has little appetite for owning applications. In that case, choosing an ERP that fits more of the business out of the box, and accepting some changes in process, may be the better path.

The Bottom Line

Composable ERP and clean core are useful ideas wrapped in a lot of marketing. The substance is a discipline: keep the ERP core standard so it can be upgraded, build what makes you different around it through stable interfaces, and review existing modifications to retire or relocate them. No vendor can sell you that discipline, but every manufacturer facing an upgrade will benefit from adopting it.

At Cherry Street, this is the work we do. We help manufacturers inventory and rationalize their ERP customizations, decide what belongs in the core and what belongs around it, and build the surrounding applications on interfaces that will survive the next upgrade.