What is causing HTTP 503 responses on calls to B2C Service REST and/or SOAP APIs?
Connect REST API, Connect Web Services for SOAP (CWS)
Oracle B2C Service
HTTP 503 responses are expected under certain conditions when using the Oracle B2C Service REST and SOAP APIs. This relates to the API Throttling capability of the product that is described in product feature documentation here. This is also described in REST API documentation here, and SOAP API documentation here ('API Throttling' section).
If REST API requests are being rejected due to API throttling, the API response will include both a HTTP 503 response, and OSC-CREST-00035 API error code. In the case of the SOAP API the HTTP 503 response there is no documented corresponding error code, and so further troubleshooting will be necessary to confirm the source of the behavior. Further, any 503 response from the Oracle API may not be logged to the Apache Web logs, as the API traffic may be blocked before it reaches the Oracle B2C Service web server hosting the primary API functionality.