Call of Segments in a Logical View
You can call Segments and Logical Views in the -CE Lines tab of the Logical View editor. In this context, a Segment that is called in a Logical View is considered as an elementary Data Element. When you enter or select a Segment call line, the Segment call definition section opens. You must indicate the Logical View attributes in this section or directly in the table. The information on the Logical View data transfer can be indicated in the table, or in a wizard that you open from this section or from the table. The selection of subschemas must be indicated in this wizard.
- Occurs
- In this field, you enter the number of occurrences on 3 numeric characters. It corresponds to the OCCURS clause. It is not possible to create a repeated group area apart from the repeated structure (see the Data Type field). Repeated Data Elements are not authorized in graphic applications.
Logical View attributes
- Data type
- When a client calls a selection service, this service can implement an extraction method and its
parameters by value. The Business Component that answers the call must recognize the extraction
method and its parameters to correctly complete the service. The only way to send this information
is through the message that is sent by the client.
The extraction method is sent to the Business Component through the technical part of the message. Parameters must be described in the application part of the message, which is in the Logical View.
In the Data type field, you specify the parameters by value for all the extraction methods that can be used by the Logical View. To do so, you call defined Data Elements. For each parameter, you enter the E type, which indicates that it is a parameter. Each identifier Data Element (U type) is an implicit parameter. The other Data Elements that describe the contents of the Logical View cannot be used as parameters. The E-type Data Element does not belong to the description of a Logical View. If necessary, you can define and call a child Data Element.Table 1. Specification of the data type Options Description None The Data Element is not used as a parameter. You indicate it for the Data Elements that describe the Logical View. U: identifier for paging The Data Element is used as a selection criterion or start key for the reading of data occurrences in the database. It is the identifier for the paging of a list for the client. As output from the server, it contains the selection criteria values of the next page. R: repeated structure There is only one repeated structure for a Logical View. A repeated structure is specified in the group Data Elements. This Data Element indicates the beginning of the repeated Data Elements. The end of the repeated Data Elements is deduced from the number of Data Elements in a group. The number of occurrences must be indicated in the Number of occurrences field in the Logical View definition. E: extraction parameter The Data Element is used as a parameter for an extraction method. The E type Data Elements must be entered in the -CE Lines before the Data Elements that describe the Logical View contents. Each identifier Data Element (U type) is an implicit extraction parameter. The other Data Elements that describe the Logical View cannot be used as parameters. If necessary, you can define and call a child Data Element.
- Data Element presence
- For each called Data Element, select one of the following check
options in the list:
Table 2. Specification of the Data Element presence Options Description O: required Required Data Element. The check for its presence is generated in the client and in the Business Component if CHECKSER=YES. Note: It includes checks in relation to the Data Element description.P: required Required Data Element. The check for its presence is generated only in the Business Component if CHECKSER=YES. Note: It includes checks in relation to the Data Element description.Blank The checks that are specified in the Data Element description are generated in the client and in the Business Component if CHECKSER=YES. F: optional The checks that are specified in the Data Element description are only generated in the Business Components if CHECKSER=YES.
- Redefines
- Redefinition is possible within a Segment or Logical View. It
generates the COBOL REDEFINES clause. The Data Element
that contains this option redefines the Data Element of the same COBOL
level that precedes it in the -CE lines. If a Data Element that redefines
another Data Element is contained in a group, it is considered to
be an elementary Data Element. It must be taken into account in the
calculation of the number of Data Elements that are contained in a
group (except for DL/1 database Segments). Note: When Data Elements are redefined, their respective lengths are not taken into account. It is your responsibility. The redefined Data Element length is used for the address calculation. Redefined Data Elements are ignored when generating for the Database Description function. If the Redefines box is checked, no initial value can be entered.
- To redefine a Data Element, select the Redefines option. A Set of Redefines line is created in the -CE lines. It contains the redefined Data Element and the preceding Data Element of the same level in the tree structure. You must then define the Occurs option in the Set of Redefines section.
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The data transfer information can also be indicated directly in the table.
-G Lines
Click -G Lines to define -GC lines (comments), -GE lines (error messages), and -GG lines (generation elements) for each Segment that is called in the Logical View.