Data retrieval

When the Entry is used in an ITP Model the data described by the Entry has to be retrieved from the database. ITP supports two interfaces to retrieve data using the ITP iSeries Connection:

*DBMS400: this can only be used when the Entry was generated; the ITP iSeries Connection itself retrieves the data from the database file the Entry was generated over.
Program interface; the ITP iSeries Connection calls the program registered in the Entry. The program is called using the library list of the host DataManager job in which it is called (refer to the "ITP Administration manual").

The function to be performed by both these interfaces is exactly the same:

Key selection: if a Main entry has formal parameters, is used in a WITH or FORALL construction with an IN (as opposed to the PATH), and no key-values are passed to the ITP Model.
Data retrieval: if an Entry is used in an ITP Model.

The Singular/Plural attribute of an Entry has no influence on the function performed for either the "key selection" or the "data retrieval". The Singular/Plural attribute only specifies how the Entry must be used in an ITP Model (in a WITH or a FORALL construct). The intended working of *DBMS400 or the program is always the same. Both the *DBMS400 interface and the program are called with two parameters for ITP internal use followed by a parameter for every Formal parameter of the Entry. The first two parameters are both defined as 10 bytes alphanumeric, the other parameters are passed conform the definitions of the appropriate Formal parameter.

Part of the Data retrieval interface is the way in which data is send to the ITP Model that uses the Entry. This is done by a call to the program ISNDDTA (since version 2.1) or the QSNDDTAQ program in the ITP iSeries Connection option "Pre-2.1 Connection legacy". The first 4 parameters of the programs are the same as the parameters of the iSeries program QSNDDTAQ (which was actually used in ITP/400):

Parameter 1	10 bytes alphanumeric	ITP internal use; is equal to the first parameter of the retrieve data interface.
Parameter 2	10 bytes alphanumeric	ITP internal use; is equal to the second parameter of the retrieve data interface.
Parameter 3	Packed decimal (5,0)	Number of bytes passed in parameter 4.
Parameter 4	Buffer with length indicated by parameter 3	A buffer containing the data of one record retrieved and to be returned to the ITP Model.