ETO terminology
Certain terms have meanings that are specific to ETO and that are therefore important for understanding and administering ETO.
Terminals
The definitions for terminal, static terminal, and dynamic terminal are described in this topic.
- A terminal is a physical VTAM® logical unit (LU) that establishes a session with IMS. A physical terminal is represented using a control block.
- When terminals are not built by ETO but are defined at system definition, they are called static terminals. When messages are sent to a static terminal they are queued to a logical terminal (LTERM) message queue, where they await retrieval by the recipient.
- When a terminal is not defined at system definition and ETO builds a terminal, that terminal is called a dynamic terminal, or an ETO terminal. For dynamic terminals, the logical terminal (LTERM) is known as a dynamic user message queue, LTERM associates the messages with the user, rather than with the physical terminal. Associating messages with the users provides more security for these users, because they can access their messages only when they sign on using their unique user ID. In addition, all users in the network can access their messages from any physical terminal, instead of being restricted to using a particular physical terminal.
Dynamic users
Definition: An ETO dynamic user is a user who signs on to a dynamic terminal and who has a unique identification (user ID) that IMS uses for delivering messages. The user is usually associated with a person but can also be associated with another entity, such as a printer.
Terminal structures
A terminal structure is an IMS control block that represents a specific terminal that is known to IMS. A terminal structure is created when the individual terminal logs on to IMS. It is deleted when the terminal logs off with no remaining associated activity (such as status that must be retained for the next connection to IMS).
User structures
A user structure is a set of IMS control blocks, including a user block and one or more LTERM blocks. The message queues are associated with the dynamic user, as opposed to the physical terminal, and they are queued to the user ID.
The dynamic user structure connects to the physical terminal only when the user signs on. This provides a secure environment, because different users accessing the same terminal cannot receive each other's messages.
- A dynamic user signs on to IMS.
- Output messages that are destined for a dynamic user are sent to the user, but the user has not signed on to IMS.
Usually, a user structure represents a person who uses IMS. The user structure name is usually the same as the user ID. A user structure can also represent a logical destination, such as a printer. In this case, the user structure name can be the same as or different from the LTERM name that your installation uses in its application programs and its exit routines. For example, you can assign the same name to a user structure for a printer that you assign to its LTERM destination node name. However, output is then queued according to the terminal, and not to the user.
The following figures show the differences between static resources and ETO dynamic resources.
