Oracle Functions does not currently support PL/SQL as a language for writing function code. PL/SQL is a procedural language used in Oracle Database for developing stored procedures, triggers, and other database-related code. However, Oracle Functions supports several other popular programming languages such as Go, Node.js, Python, and Java, allowing developers to choose the language that best suits their application requirements and their familiarity with the language. While PL/SQL is powerful for working with the Oracle Database, it is not an option for writing function code in the Oracle Functions serverless architecture.

The two statements that are NOT valid regarding the Oracle Cloud Infrastructure (OCI) Streaming service are: A stream can be configured with either a public or a private endpoint with support for customer managed encryption keys. This statement is not valid because the OCI Streaming service currently supports only private endpoints. Customer managed encryption keys are not currently supported for OCI Streaming. OCI Streaming can support up to 2,000 requests per second to each partition. This statement is not valid because the throughput of a stream is not defined by the partition in terms of requests per second. The throughput of a stream is defined in terms of data input and output rates. Each partition provides 1 MB/sec data input and 2 MB/sec data output, but it does not correspond to a specific number of requests per second. The other statements are valid: OCI Streaming stores all data for 24 hours by default, but that can be extended up to 7 days. Although OCI Streaming automatically encrypts all data while in transit, it is the developer's responsibility to encrypt data at rest, if needed.

In the given scenario, the developer should use the approach of creating an authorizer function using token-based authorization. Token-based authorization is a commonly used approach for authenticating API requests. It involves generating and issuing tokens to API callers, which they can then include in the requests they make to the API. The tokens serve as proof of authentication and are validated by the server to ensure the caller's identity and access rights. By creating an authorizer function using token-based authorization, the developer can implement a custom scheme that accepts string-based parameters from the API caller. This allows the developer to define their own authentication logic and validate the provided tokens according to their requirements. The authorizer function can be configured in the OCI API Gateway to be invoked before forwarding the request to the web application. It will perform the necessary token validation and authentication checks, allowing only authorized requests to access the protected resources of the web application.

The correct answer is: Invoke from the Docker CLI. Executing a function deployed in Oracle Functions is typically done using the following options: Invoke from the Fn Project CLI: The Fn Project CLI provides a command-line interface specifically designed for interacting with Oracle Functions. You can use commands like fn invoke to invoke a function. Trigger by an event in the Oracle Cloud Infrastructure (OCI) Events service: You can configure events in OCI to trigger your function based on various criteria, such as object storage events, resource state changes, or scheduled events. Invoke from the OCI CLI: The OCI CLI (Command Line Interface) allows you to interact with various services in Oracle Cloud Infrastructure, including Oracle Functions. You can use the fn invoke command to invoke a function. Send signed HTTP requests to the function's invoke endpoint: Oracle Functions provides an HTTP endpoint that can be used to invoke functions. You can send signed HTTP requests to this endpoint using tools or programming languages that support making HTTP requests. On the other hand, invoking a function deployed in Oracle Functions using the Docker CLI is not a valid option. The Docker CLI is primarily used for managing Docker containers and images, and it does not provide a direct mechanism for invoking functions in Oracle Functions.

The valid OKE cluster network configuration that meets the requirement of having the least attack surface while still allowing direct access to the deployed applications from the Internet is: Private subnets for nodes and the Kubernetes API endpoint; public subnets for load balancers. By placing the nodes and the Kubernetes API endpoint in private subnets, they are not directly accessible from the Internet, reducing the attack surface. The load balancers, on the other hand, are placed in public subnets, allowing them to be accessed from the Internet and serve as the entry point for accessing the deployed applications. This configuration ensures that the critical components of the cluster, such as the nodes and the API endpoint, are protected within the private network, while still providing accessibility to the applications through the load balancers. It helps to enhance security by limiting direct access to the internal components of the cluster while maintaining the availability of the deployed applications.