Because COBOL ISAPI subroutines basically guarantee upward compatibility of sources for the COBOL CGI subroutines, migration of Web Applications created with COBOL CGI subroutines to those created with COBOL ISAPI subroutines is easy. However, there are some ISAPI specific functions, and so some program corrections and changes of the Compilation and link methods are needed. The following describes some points to be noted for migration.
First, the following table lists the differences between applications created using COBOL CGI subroutines (hereafter referred to as CGI applications) and those created using the COBOL ISAPI subroutines (hereafter referred to as ISAPI applications).
No. | Item | CGI application | ISAPI application |
|---|---|---|---|
1 | Application format | Main program (EXE) | Subprogram (DLL) |
2 | Run unit | Process | Thread |
3 | Module configuration | Free | Prepare GetExtensionVersion, HttpExtensionProc, and TerminateExtension as export functions, and otherwise free.. |
4 | Interface area with a WWW Server | Not required | Required |
5 | Return code | Not required or free | Required. The values have fixed meanings. |
6 | Manipulation of environment variables | Arbitrary | Limited |
7 | Manipulation of CGI environment variables | Can be manipulated using a provided subroutine or the DISPLAY/ACCEPT statements. | Can be manipulated using a provided subroutine. |
To convert a CGI application into an ISAPI application, you need to modify the above differences. The details are described in "Application Formats" and later.
Note that the following subroutines, although provided as COBOL ISAPI subroutines to maintain compatibility, can be used only in an environment where a Web application runs in the ASCII code system. It is recommended to use the conversion to ISAPI as an opportunity to replace these subroutines with the alternative ones.
Old Subroutine name | New Alternative subroutine |
|---|---|
COBW3_NAME | COBW3_GET_VALUE COBW3_GET_VALUE_XX COBW3_GET_VALUE_NX COBW3_GET_VALUE_XN COBW3_GET_VALUE_NN |
COBW3_VALUE | COBW3_CHECK_VALUE COBW3_CHECK_VALUE_X COBW3_CHECK_VALUE_N |
COBW3_CNV_SET | COBW3_SET_CNV COBW3_SET_CNV_XX COBW3_SET_CNV_NX COBW3_SET_CNV_XN COBW3_SET_CNV_NN |
COBW3_CNV_DEL | COBW3_DEL_CNV COBW3_DEL_CNV_X COBW3_DEL_CNV_N |
COBW3_CNV_INIT | COBW3_INIT_ CNV |
