https://help.mulesoft.com/s/feed/0D52T000055pzgsSAA.

Security Assertion Markup Language (SAML) is an open standard that allows identity providers (IdP) to pass authorization credentials to service providers (SP).
SAML transactions use Extensible Markup Language (XML) for standardized communications between the identity provider and service providers.
SAML is the link between the authentication of a user's identity and the authorization to use a service.
WS-Security is the key extension that supports many authentication models including: basic username/password credentials, SAML, OAuth and more.
A common way that SOAP API's are authenticated is via SAML Single Sign On (SSO). SAML works by facilitating the exchange of authentication and authorization credentials across applications. However, there is no specification that describes how to add SAML to REST web services.

* If we store Correlation id value in step 1 as Mule event variables/attributes, the values will be cleared after server restart and we want system to be fault tolerant.
* The Correlation ID value in Step 1 should be stored in a persistent object store.
* We don't need to store Correlation ID value in Step 3 to persistent object store. We can store it but as we also need to make application performant. We can avoid this step of accessing persistent object store.
* Accessing persistent object stores slow down the performance as persistent object stores are by default stored in shared file systems.
* As the SOAP service is idempotent in nature. In case of any failures , using this Correlation ID saved in first step we can make call to SOAP service and validate the Correlation ID.
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Additional Information:
* Competing Consumers are multiple consumers that are all created to receive messages from a single Point-to-Point Channel. When the channel delivers a message, any of the consumers could potentially receive it. The messaging system's implementation determines which consumer actually receives the message, but in effect the consumers compete with each other to be the receiver. Once a consumer receives a message, it can delegate to the rest of its application to help process the message.

* In case you are unaware about term idempotent re is more info:
Idempotent operations means their result will always same no matter how many times these operations are invoked.

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