Filter
Top Products
9.4.5.1 TCP/IP Applications using the Sockets API for Assembler
VSE/ESA applications based on the SOCKET Assembler macro cannot be used
on an OS/390 system. They have to be recoded for the OS/390 TCP/IP.
9.4.5.2 TCP/IP Applications using the Preprocessor API
The HLL preprocessor API which is available on VSE/ESA for PL/I, Assembler
and COBOL is not compatible with the OS/390 TCP/IP interfaces. Therefore,
these programs have to be recoded for the OS/390 system as well.
9.4.5.3 TCP/IP Applications using the BSD/C Sockets
The BSD (″Berkeley″) C sockets interface on VSE/ESA is almost compatible to
the C socket API on OS/390. Only some additional (proprietary) functions or
parameters of the BSD/C interface are not supported by TCP/IP on OS/390. This
is why VSE/ESA TCP/IP applications based on the BSD/C sockets usually can be
migrated to OS/390 with only minor code changes.
9.4.5.4 TCP/IP Applications using the LE/VSE C Socket API
It is highly recommended to use the IBM C for VSE/ESA compiler, the IBM
Language Environment for VSE/ESA (LE/VSE) C run-time environment and the
LE/VSE C socket interface to write TCP/IP applications on VSE/ESA. These are
compatible with the OS/390 X/Open (XPG4.2) compliant socket interfaces. This
assures the maximum in compatibility and portability for cross platform
development. In this case, migrating the applications is just a matter of relinking
them on the OS/390 system. More information about sockets programming can
be found in the
TCP/IP for VSE/ESA User
′
s Guide
, SC33-6601.
The VSE applications don′t have to be necessarily C program since you can use
the LE/VSE C socket API also from within other languages using the ILC
(InterLanguage Communication). This is described in the book
Writing
Interlanguage Communication Applications
, SC33-6686.
9.4.5.5 CGI Programs
If you are running VSE/ESA as a Web server and therefore have implemented
CGI (Common Gateway Interface) programs on the VSE system, all these
programs have to be rewritten on OS/390 since the CGI interface on OS/390 is
totally different to the one on VSE/ESA.
9.4.6 Security
Security is an important consideration for an OS/390 system, especially if it′s
connected to large TCP/IP networks or even the Internet. TCP/IP on OS/390 has
some built-in internal security mechanism and relies on the services of an
external security manager such as IBM Resource Access Control Facility (RACF).
Basic TCP/IP security definitions on VSE (such as user ID/password) can be
easily defined in RACF for the OS/390 system. If you have implemented your own
security exit on VSE, similar exits can be written for the FTP server function on
OS/390. Furthermore, RACF can be used to protect whole libraries or single
resources from unauthorized TCP/IP access.
Additionally, the OS/390 system can be run as a firewall to secure the system
against users coming through the TCP/IP network.
Generally, you can achieve a higher level of security on the OS/390 system
which, of course requires a little more effort to set it up.
196 VSE to OS/390 Migration Workbook