Remote system communication
The z/OS® operating system is different from a workstation operating system architecturally. To facilitate the transport of data sets and files between the remote system and the client workstation, information about data transfer and port connections must be defined. Information about data transfer is called mapping information.
- Port
- Defines the communication channel that is used to transport data between the workstation and remote system.
- Mapping
- Defines the information that is required to move files between the workstation and remote system:
- File type
- Transfer mode
- Host and local code pages
Port
A port is an end point for communication between applications. It is the logical connection between the remote system components and the workstation component. The port provides queues for sending and receiving data. Each port has a port number for identification. The port number must be specified when you create a connection between the remote system and workstation.
The system programmer for your site defines a port number during installation for a remote daemon or REXEC port. You must contact the system programmer for your site to obtain the type of port and the port number.
Mapping
Most operating systems recognize and differentiate files by their file extensions, which are referred to as the file type. For example, a file with the .txt extension is processed as a text file, while a file with the .html extension is processed as a hypertext markup language file. On the z/OS system, the concept of file extensions does not exist. Therefore, each data set type or file must be explicitly defined so that it is transported and processed between the remote system and the workstation correctly.
The transfer mode refers to whether the file is transported as text or binary.
A computer system translates keyboard inputs to character values according to the code page that is specified on each system. z/OS systems employ the EBCDIC family of code pages and most workstation systems employ the ASCII family of code pages. When a file is transported between these two operating systems, code-page conversion must be taken into account so that the file is translated and displayed correctly on the destination system. IBM® Developer for z/OS handles this translation automatically, but to do so, it must be told in advance what code pages are being used on the remote system and the workstation.
Specifying mapping definitions provides the file type, transfer mode, and code page information that is required to transfer data between the remote system and workstation. The term mapping is used throughout the product documentation to refer to defining file transfers and other information. Developer for z/OS provides a set of default mappings to simplify the setup. For example, all data sets with an end qualifier COBOL are mapped to the .cbl file extension and text transfer mode. This mapping causes the members to be treated as COBOL source files when they are transported and opened on the workstation. Another default mapping assigns load modules with the end qualifier LOAD to the .exe file extension and binary transfer mode.
Each z/OS system can have its own mapping. Mapping definitions are defined by using the z/OS File System Mapping view.