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Oracle Visual Builder: Applications That Outlive Their First Release · Module 6 · Connecting to Fusion

CORS and the errors it produces

Lesson 65 of 176 · 3 min

Why a call WORKS IN ONE PLACE AND NOT ANOTHER, and how to RECOGNISE THIS FAILURE FROM ITS SYMPTOM rather than by elimination. This is a browser rule rather than an Oracle one, and it is included because it costs people a day the first time and ten seconds every time after — entirely on whether they recognise it. THE RULE IS THAT A PAGE MAY NOT READ A RESPONSE FROM A DIFFERENT ORIGIN UNLESS THAT ORIGIN SAYS IT MAY. The browser sends the request and then refuses to hand the result to your page, because the server did not include a header permitting your application's origin. THE SYMPTOM IS THE THING TO LEARN, BECAUSE IT IS MISLEADING IN A SPECIFIC WAY. The console says the request was blocked by CORS policy, and the network tab shows a request that appears to have succeeded — or an OPTIONS request you…

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In this module: Module 6 · Connecting to Fusion

  1. 1What a service connection is
  2. 2Creating one against a Fusion REST APIFree preview
  3. 3Authentication, and whose identity is used
  4. 4Why a shared service account is usually wrong
  5. 5Query parameters, filtering and fields
  6. 6Pagination, properly
  7. 7Writing back to Fusion
  8. 8When the shape changes underneath you
  9. 9Calling an OIC integration instead
  10. 10Handling a service that is down
  11. 11CORS and the errors it produces
  12. 12What breaks: four connection failures
  13. 13Lab briefing · Connect, over-fetch, then fix it