We need get "Total Open Receivables Value" of a customer since a external system

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We need get "Total Open Receivables Value" of a customer since a external system. We need a communication like a Webservices, because it must support a high number of requests and answer quickly.

We are aware of the existing option of building a report in OTBI and extracted the data required  as csv file  to be loaded into the target system  is not effective  as this information will be requested very often.

There is some webservice in standard Oracle Fusion for get this value?

Can we develop a webservice for get this value?

I attach a screenshot of the field.