REST vs SOAP vs OData: Which Integration Standard Should Your Enterprise Use?

This article draws on WEM No-Code's experience deploying enterprise integration workflows across SAP, ERP, and legacy system environments in regulated European industries, including financial services, manufacturing, and government. Where SAP-specific behavior is described, references reflect SAP S/4HANA and SAP BTP documentation.

When your organization decides to connect two enterprise systems, whether that's SAP to a logistics platform, a CRM to a customer portal, or a legacy ERP to a modern workflow layer, one of the first technical decisions is which integration standard to use.

REST, SOAP, and OData are the three standards you'll encounter most frequently in enterprise environments. Each represents a different philosophy about how systems should communicate, what data formats they should exchange, and how much structure and governance the protocol itself should enforce.

Choosing incorrectly doesn't mean the integration fails to work. It means it works until something changes, a system upgrade, a compliance audit, a new data volume, and then it becomes difficult and expensive to maintain. This guide explains what each standard is, where each performs best, and how to make the right choice for your enterprise context, including the governance layer that no standard provides on its own.

Most teams treat the choice of integration standard as a developer decision: pick whatever the connecting system supports, build the integration, move on. That approach produces integrations that work in development but create compounding problems in production.

The standard chosen determines three things that matter to the business as much as to IT:

• Data structure and format: how data is packaged, transmitted, and parsed on the receiving end. The wrong format creates translation overhead or, in high-volume environments, performance bottlenecks.
• Error handling and reliability: some standards have built-in retry and fault tolerance; others leave that entirely to the implementation. When an integration fails silently in a regulated environment, that's a compliance event, not just a technical issue.
• Governance and auditability: what the protocol enforces about security, authentication, and message integrity, and what has to be built separately. This is the gap most integration guides skip.

These three dimensions, not raw performance benchmarks, are what enterprise teams should actually weigh when choosing a standard.

REST, Representational State Transfer, isn't a protocol. It's an architectural style for designing communication between systems over HTTP. REST doesn't specify data formats, error handling, or authentication; it defines principles about how resources should be addressed, how state should be managed, and how standard HTTP verbs (GET, POST, PUT, DELETE, PATCH) should map to operations.
In practice, REST has become the default standard for modern API design because it's flexible, stateless, and works well with JSON, the data format most modern applications and cloud services use natively.

REST's flexibility is also its governance gap. Because REST is an architectural style rather than a protocol, it enforces nothing about security, message signing, transaction integrity, or error handling.

Two different REST APIs can behave completely differently; one might include comprehensive error codes and retry headers, another might return HTTP 200 for a failed operation. Without a governance layer above the REST calls, something enforcing consistent authorization, logging, and error handling, REST integrations can be difficult to audit and harder to troubleshoot when they fail.

SOAP, Simple Object Access Protocol, is a strict XML-based messaging protocol. Unlike REST, SOAP is a formal specification: it defines exactly how messages must be structured (in an XML envelope), how services must be described (via WSDL, Web Services Description Language), and how security, transactions, and reliability must be handled (via WS-* extension standards such as WS-Security and WS-ReliableMessaging).

SOAP was the dominant enterprise integration standard from roughly 2000 to 2010 and remains deeply embedded in legacy enterprise environments, particularly in banking, insurance, government, and older SAP deployments where integration was built on RFC (Remote Function Call) or BAPI (Business Application Programming Interface) endpoints exposed via SOAP wrappers.

SOAP's rigidity, the same feature that makes it reliable, makes it expensive to maintain. WSDL contracts are verbose and tightly coupled; when the underlying service changes, the WSDL needs updating and every consuming system needs to adapt.

In enterprise environments that deploy frequently, SOAP integrations become change bottlenecks. They also need specialized expertise to build and debug correctly, which increases both development time and the risk of misconfiguration in the security layer.

OData, Open Data Protocol, is a REST-based protocol developed by Microsoft and standardized by OASIS. It extends REST with a formal query language, a standardized metadata format (the $metadata endpoint), and conventions for filtering, sorting, and paginating data across collections. OData is, in effect, a structured REST standard: it takes REST's flexibility and adds the consistency and discoverability enterprise applications need when working with large, structured datasets.

In the SAP ecosystem, OData is the native API standard for SAP Fiori applications and SAP S/4HANA. Any enterprise running SAP S/4HANA will have OData services as its primary programmatic interface to SAP data, from materials management to financial postings to sales order processing.

OData's query power is also a governance exposure. An OData service that isn't properly secured can be queried for data far beyond what the consuming application should access. The $filter and $expand operators, used carelessly, can extract large volumes of sensitive data from SAP in a single request. Governance controls, field-level restrictions, query depth limits, and authorization scoping need to be applied at the service layer, not assumed from the protocol.

The table below summarizes the decision-relevant differences across the three standards for enterprise integration teams.

No single standard is universally superior. The right choice depends on what the target system exposes natively, what the data volume and latency requirements are, and what governance obligations apply to the data being exchanged.

For enterprises running SAP, which includes a significant share of European large-cap companies across manufacturing, financial services, and government, the integration standard question is often partially answered by SAP itself.

• Legacy SAP ECC: RFC and BAPI interfaces, typically exposed via SOAP wrappers for external consumption. If your SAP landscape is still on ECC, SOAP is likely what the system speaks natively.
• SAP S/4HANA: OData v2 and v4 are the native API standards, and SAP recommends OData v4 for all new developments. REST remains relevant for integration with SAP BTP services.
• SAP BTP Integration Suite: supports REST, SOAP, and OData, acting as a mediation layer between SAP systems and external services. If your organization uses BTP as an integration layer, the standard choice may be abstracted by the platform.

The practical implication: an enterprise extending SAP S/4HANA to a no-code workflow platform or a customer portal should generally use OData natively for SAP data access. Wrapping those OData services in a REST abstraction is sometimes done for simplicity, but introduces a translation layer that can obscure OData's rich metadata and filtering capabilities.

For the fuller picture of how this plays out in practice, see how WEM No-Code extends SAP without custom development.

REST, SOAP, and OData each address different aspects of how data moves between systems. None of them address who authorized the data to move, what business rules govern the decision to trigger the integration, or how the result gets logged for audit purposes.

That's the governance gap. It isn't a failure of the standards; it's simply outside their scope. Governance is the responsibility of the layer above the integration standard: the orchestration layer.
In regulated industries, the governance gap has direct compliance consequences. GDPR expects personal data transferred between systems to be authorized, logged, and retrievable on request.

DORA, the EU's Digital Operational Resilience Act, expects financial entities to demonstrate the resilience and audit-readiness of their integration architecture. The EU AI Act imposes similar requirements on AI systems that consume API-connected data as inputs to decisions.

An integration built on the most technically correct standard, WS-Security-signed SOAP over a dedicated connection, is still a compliance liability if there's no governance record of who authorized it, what data it accessed, and what happened when it failed.

Orchestration software sits above the individual API calls and enforces the governance model: who can trigger this process, under what conditions, with what data, subject to what human review checkpoints, and with what complete audit trail. For the broader picture of what that layer does, see What Is Orchestration Software?.

WEM No-Code doesn't require business teams to choose between REST, SOAP, and OData, or to manage protocol differences at the workflow layer. Its integration architecture handles all three natively, letting business teams configure multi-system workflows that call SAP OData services, legacy SOAP endpoints, and modern REST APIs within the same governed process.

The governance model travels with the workflow, not with the protocol. A WEM No-Code workflow that calls an SAP OData service to retrieve an order, a REST API to check delivery status, and a SOAP interface to confirm a financial posting applies the same authorization model, audit logging, and human review rules to each step, regardless of the underlying standard.

This matters for enterprise teams managing heterogeneous system landscapes, which is the reality for most large European organizations. Arval connected WEM workflows to their existing core system without writing code and without standardizing on a single protocol first. The orchestration layer handled the protocol differences; the governance model handled the compliance requirements.

For organizations evaluating how to extend SAP S/4HANA workflows to business teams, or how to add governed AI agents that consume SAP data as inputs, WEM No-Code's SAP integration layer provides the connection without the protocol management overhead.