Explanation
The following are the integration frameworks that have been released for ABAP cloud development:
SOAP consumption: This framework allows you to consume SOAP web services from ABAP cloud applications. You can use the ABAP Development Tools in Eclipse to create a service consumption model based on a WSDL file or URL. The service consumption model generates the required ABAP artifacts, such as proxy classes, data types, and constants, to access the web service. You can then use the proxy classes to call the web service operations from your ABAP code1 Business Events: This framework allows you to publish and subscribe to business events from ABAP cloud applications. Business events are messages that represent a change in the state of a business object or process. You can use the ABAP Development Tools in Eclipse to create a business event definition based on a CDS view entity or a projection view. The business event definition specifies the event key, the event payload, and the event metadata. You can then use the ABAP Messaging Channel (AMC) framework to publish and subscribe to business events using the AMC API2 OData services: This framework allows you to expose and consume OData services from ABAP cloud applications. OData is a standardized protocol for creating and consuming RESTful APIs. You can use the ABAP RESTful Application Programming Model (RAP) to create OData services based on CDS view entities or projection views. The RAP framework generates the required OData metadata and runtime artifacts, such as service definitions, service bindings, and service implementations. You can then use the SAP Gateway framework to register and activate your OData services. You can also use the ABAP Development Tools in Eclipse to consume OData services from other sources using the service consumption model3 The other integration frameworks are not released for ABAP cloud development, as they are either not supported or not recommended for cloud scenarios. These frameworks are:
CDS Views: CDS views are not an integration framework, but a data modeling framework. CDS views are used to define data models based on database tables or other CDS view entities. CDS views can have associations, aggregations, filters, parameters, and annotations. CDS views can also be used as the basis for other integration frameworks, such as OData services or business events4 Business Add-ins (BAdls): BAdls are not supported for ABAP cloud development, as they are part of the classic ABAP enhancement framework. BAdls are used to implement custom logic in predefined enhancement spots in the standard SAP code. BAdls are not compatible with the cloud strategy and the clean core paradigm, as they modify the SAP code and can cause upgrade and maintenance issues. For ABAP cloud development, SAP recommends using the key user extensibility tools or the side-by-side extensibility approach instead of BAdls.
References: Consuming SOAP Services - ABAP Keyword Documentation, Business Events - ABAP Keyword Documentation, OData Services - ABAP Keyword Documentation, CDS Data Model Views - ABAP Keyword Documentation, [Business Add-Ins (BAdIs) - ABAP Keyword Documentation]

Explanation
In ABAP SQL, an alias is a temporary name that can be assigned to a field or a database table in a query. An alias can be used to make the query more readable, to avoid name conflicts, or to access fields or tables with long names. An alias is created with the AS keyword and is only valid for the duration of the query1.
The following are examples of how to assign an alias to a field or a database table in ABAP SQL:
B: field (from field list): A field is a column of a table or a view that contains data of a certain type. A field can be assigned an alias in the field list of a SELECT statement, which specifies the fields that are selected from the data source. For example, the following query assigns the alias name to the field carrname of the table scarr:
SELECT carrid, carrname AS name FROM scarr.
The alias name can be used instead of carrname in other clauses of the query, such as WHERE, GROUP BY, ORDER BY, and so on2.
C: database table: A database table is a collection of data that is organized in rows and columns. A database table can be assigned an alias in the FROM clause of a SELECT statement, which specifies the data source that is selected from. For example, the following query assigns the alias c to the table scarr:
SELECT c.carrid, c.carrname FROM scarr AS c.
The alias c can be used instead of scarr in other clauses of the query, such as WHERE, JOIN, GROUP BY, ORDER BY, and so on3.
The following are not valid for assigning an alias in ABAP SQL:
A: order criterion (from order by clause): An order criterion is a field or an expression that is used to sort the result set of a query in ascending or descending order. An order criterion cannot be assigned an alias in the ORDER BY clause of a SELECT statement, because the alias is not visible in this clause. The alias can only be used in the clauses that follow the clause where it is defined1.
D: group criterion (from group by clause): A group criterion is a field or an expression that is used to group the result set of a query into subsets that share the same values. A group criterion cannot be assigned an alias in the GROUP BY clause of a SELECT statement, because the alias is not visible in this clause. The alias can only be used in the clauses that follow the clause where it is defined1.
References: 1: ALIASES - ABAP Keyword Documentation 2: SELECT List - ABAP Keyword Documentation 3: FROM Clause - ABAP Keyword Documentation

Explanation
The function find_any_not_of returns the position of the first character in the string val that is not contained in the string sub. If no such character is found, the function returns 0. In this case, the string val contains only the characters A, B, and a, which are all contained in the string sub, so the function returns 0. The other functions return positive values, as follows:
Count_any_of returns the number of occurrences of any character in the string sub within the string val.
In this case, it returns 8, since there are 8 A's and B's in val.
Count returns the number of occurrences of the string sub within the string val. In this case, it returns 2, since there are 2 AB's in val.
find_any_of returns the position of the first character in the string val that is contained in the string sub.
In this case, it returns 1, since the first character A is in sub. References: String Functions - ABAP Keyword Documentation, Examples of String Functions - ABAP Keyword Documentation