The Server Dialog and Server entities
The purpose of these entities is to develop and generate the server-side components of client/server graphic or textual applications.
The Server Dialog is a logical envelope that groups the various server components of an application.
In the Server Dialog, you give the general characteristics of the application. You specify the generation variants and options that apply by default to all the attached components.
- In an architecture without monitor, the client components directly
communicate with the server components. Each Business Component is
directly called by the Client or by the Client Monitor.
The structure of the service does not depend on the presence or absence of a monitor.
However, you must enter the processing specific to the communications technology or the security system in use in each Business Component.
The processing that is specific to the database management is specified in each service.
The database connection or opening is optionally indicated at the beginning of the Business Component processing.
- In an architecture with a monitor, the Server Monitor calls the appropriate service. It then
gives the control either to the Client Monitor or directly to the Client.
A Monitor groups common information and processing (communications management, compacting, trace, COMMIT, ROLLBACK, site-specific features). For some environments, like MICRO FOCUS and TUXEDO, using a monitor is a requirement.
However, some requirements of the application (confidentiality, data encryption) or technical constraints (communication protocols) require the use of an architecture with a monitor program. The monitor options make it easier to interface with the communication method and to insert data security and encryption/decryption processing.
The Business Component
A Business Component supports a set of services on a Logical View.
These services can be generic and dedicated to selections and updates on a Logical View. They can also be specific and support functional requirements.
- Accessing the external resources (files, databases),
- Completing checks and updates,
- Completing specific processing (calculations, extraction methods, and so forth),
- Managing the errors.
Generic services are independent of the storage medium that is used to manage their persistence.
A Business Component then describes the relations between a Logical View and the persistence objects that are used to select or update its instances.
The Server Monitor
- Receives the information that is sent by the client through the communication area,
- Calls the Server that corresponds to the service requested by the client,
- Returns the information to the Client Monitor.
The Error Message Server
The Error Message Server generates the messages of the errors that are detected by the Business Components. These messages are stored in a dedicated generated file.
The Initialization and Termination Business Component
An Initialization and Termination Business Component implements specific processing before and after the running of a request.
An Initialization and Termination Business Component is called before the first call to the Business Component that is associated with the request and after the last Business Component.
It is available either for an initialization or for a termination process.
For an initialization process, only the data that is sent by the client component through the user buffers can be processed in input.
Therefore, the generation of an Initialization and Termination Business Component contains the access functions and PERFORM instructions of the services that are associated with the Business Components.
Generation
For explanations on the contents of the generated code, see COBOL description of a generated Server.