---
schema_version: "1"
id: e41db670efa9634cdd70ff7aa1688f04cf5eef7d455e718a187564b2ad3c7e7b
title: Apex Class Names and Developer Names
collection: admin
version: current
locale: en-us
portal_url: https://docs.salesforce.com/admin/current/en-us/platform/264-0-0/external_services_schema_def_apex_class_names.md
canonical_url: https://help.salesforce.com/s/articleView?id=platform.external_services_schema_def_apex_class_names.htm&release=264.0.0&type=5
source_site: help.salesforce.com
content_type: documentation
content_hash: e784dcfd6659dd54688ab4f6a39d5d0b61b8877f2e408784ee208703802a4210
description: Learn how External Services derives Apex class names from your schema.
products:
  - Salesforce Platform
  - Security
release: "264"
---
# Apex Class Names and Developer Names

Learn how External Services derives Apex class names from your schema.

### Required Editions

<table class="slds-table slds-table_bordered slds-max-medium-table_stacked slds-m-bottom_small edition"><colgroup><col></colgroup><tbody><tr class=""><td class="slds-cell-wrap" style="vertical-align:top;">Available in: Lightning Experience</td></tr><tr class=""><td class="slds-cell-wrap" style="vertical-align:top;">Available in: <strong>Enterprise</strong>, <strong>Performance</strong>, <strong>Unlimited</strong>, and <strong>Developer</strong> Editions</td></tr></tbody></table>

The derived Apex class name for a registered API specification schema object can be a maximum of 255 characters. Ensure that class names are the correct length. To create a shorter name if errors are encountered during registration, choose a short service name, or edit the schema object name definition.

The _operation_ developer name is derived from the registered API specification. The _object_ developer name is derived from the Apex class name. The developer name must fit within a maximum of 80 characters. If the name is larger than 80 characters, a unique developer name is automatically derived to fit within 80 characters. If the individual derived object or operation unique developer names in the nested data structure don't themselves exceed 80 characters, then the nested data structure name can go up to 255 characters. If name collision errors are encountered for existing registrations, for example, to activate additional operations, try these steps:

- If the registration has been distributed in a managed package or is in use by flows, save a new copy of the registration.
- If the registration isn’t in use, either delete and recreate the registration or make a copy, delete the original registration, and save the copy as the original registration.

#### See Also

- [Schema Examples](https://help.salesforce.com/s/articleView?id=platform.external_services_examples.htm&release=264.0.0&type=5 "Explore various scenarios with OpenAPI 2.0 and OpenAPI 3.0 compliant JSON or YAML schemas supported by External Services. The examples cover schema elements like HTTP header as input parameters, and include example usage in Apex. Understanding the examples helps with proper syntax and code placement.")
- [Invoke External Service Callouts Using Apex](https://help.salesforce.com/s/articleView?id=platform.external_services_apex_invoking.htm&release=264.0.0&type=5 "You can call external service registrations natively from Apex. Make a callout to an external service like the Apex Http Class without the need to write boilerplate code. The registered services are strongly typed in Apex with the registration’s schema as Apex types. These Apex types reflect your registered service’s specification, making the Apex compiler do the heavy lifting for you.")