Appendix D Glossary

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A

Absolute Pathname

A pathname that begins with the root directory, such as /SYS/PUB/TDP. See also pathname and relative pathname.

Artificial Member

Workgroup membership is composed of natural and artificial members. A process becomes an artificial member when it is explicitly placed into the workgroup via :ALTPROC or AIFPROCPUT. A process remains an artificial member of its assigned workgroup until:

• the workgroup is purged, or
• the process is explicitly released from its artificial assignment via the :ALTPROC command or AIFPROCPUT.

That is, an artificial member is not affected by changing one of the process attributes used in workgroup assignment. In addition, a scan would only effect the process if the process' workgroup had a purge pending.

Asynchronous Port

A port that provides the capability of interrupting the creator upon receipt of a message to that port. User code will only be interrupted when it is executing at privileged levels 2 or 3, and it is not set critical or in system code. Asynchronous ports may only have one receiver and it must be the port creator. Asynchronous ports are NOT permanent.

B

Base

The base is the highest priority value (lowest numeric value) of processes within that workgroup (BASE=Value). Values can range between the priority values of 150 and 255. Internally the priorities range from 32767 to 0. AIFSCGET/PUT return or modify internal priorities. Processes will begin their transactions at the base priority and decay as they consume CPU. The base is a required workgroup characteristic.

Boost Property

The boost property can be set to either decay or oscillate (BOOST= {DECAY, OSCILLATE}). A value of decay is the default and means the priority of a process within that workgroup will begin at the base and decay as the process consumes CPU. A value of oscillate indicates that the priority of the process will be reset to the base if it decays to the limit (the priority of the process will oscillate between the base and limit priorities). The boost property is an optional workgroup characteristic with a default value of DECAY.

C

CI

CI is an abbreviation for the command interpreter. The CI analyzes and processes commands entered during a session or submitted as part of a job.

Connectionless Send

The ability to send to an AIF port without having previously done an AIFPORTOPENi on that port. The only type of Vconnectionless send that can be done is a "no wait" send.

Constant Priority Process

This process does not decay and remains at the same level regardless of the queue the process is in. By default, only the processes in AS, BS, and certain processes in CS queue of type UCOP and System belong to this process category.

CM Files

The MPE/iX file system currently consists partially of NM files and CM files. Consequently, CM code handles certain types of files after switching to CM. Files that require switching to CM are called CM files.

Current Working Directory (CWD)

The directory in which you are working and from which relative pathnames are resolved. See also directory and relative pathname.

CWD

An acronym for Current Working Directory.

D

Decayable Boosting

This causes the priority to descend gradually through a series of drops until a transaction is completed or decays to the bottom of a queue. After this occurs the priority resets to the base of the CS queue.

Default Workgroups

One of five system-defined workgroups created to provide backward compatibility with the five scheduling queues. These workgroups, AS_Default, BS_Default, CS_Default, DS_Default, and ES_Default, are created with the same scheduling characteristics as their namesake and have the scheduling queue as their only membership criterion. The characteristics of the AS_Default and BS_Default workgroups cannot be changed. The characteristics of the CS_Default, DS_Default, and ES_Default can be changed through AIFSCPUT and AIFWGPUT.

directory

A special kind of file that contains entries that point to other files. It acts like a container for files and other directories. On MPE/iX, accounts and groups are special types of directories.

E

Envelope

The envelope in the context of IPC and message-passing is analogous to the envelope you use to send a letter through the Postal Service. The envelope is the overhead portion of the total data required to send a message from a sender process to a receiver process. The envelope contains the priority of the message, reply information (the return address), and other miscellaneous information needed for routing and scheduling.

Envelope Code

The envelope code is an integer value that can be passed with any message. This value is available to a receiver process without reading the actual message. If the message sent can fit within an integer value, a zero length message can be sent with the actual message contained entirely in the envelope code.

F

FIFO

FIFO is an abbreviation for first in first out. Since messages can be assigned a priority between 0 and 31, where 0 has the highest priority, a message of priority 0 is received before a message of priority 1, even if the priority 1 message arrived in the port first. Messages sent with the same priority are delivered in the same order they were sent, or FIFO.

File Code

A file code is a four-digit integer that identifies the function of a special purpose file. For example, a V/3000 forms file has a file code of 1035. For a list of file code numbers and their meanings, consult the File System Reference Manual.

File Equation

A file equation directs the input to, or output from, a program, job, or session. You create a file equation by using the File command to equate a file name to another file or device.

File Name

Most of the AIF interfaces accept and return fully qualified file names in a single standard format.

File Number

Each OPEN (FOPEN or HPFOPEN) returns a number to the caller which is a process-specific handle for this instance of the OPEN. For the remainder of the section, a file number always signifies the file context addressed by this process-specific handle.

H

Handler

The code that is specified to handle interrupts from an asynchronous port. This user-written routine will be required to have only one parameter, an AIF port ID. This ID is passed to the handler upon its invocation, by the AIF subsystem. The address of the handler must be provided at creation time to the AIFPORTOPEN for an asynchronous port.

HFS

An acronym for the hierarchical file system.

hierarchical file system (HFS)

A file system that is tree structured and can contain files at many different levels. This file organization is obtained through the use of directories, which can contain files and other directories.

Home Group

The home group is the group assigned to a user when the user name is defined with the Newuser command. The group is the user's default logon group if a group name is not specified with the Hello or Job command.

I

IPC

IPC is an abbreviation for Inter Process Communication, which is message-passing between processes. Although normally occurring between two or more different processes, the communication can also occur between a single process and itself.

J

Job

A job is a sequence of instructions issued to the computer that does not require an interactive dialog between the user and the computer. Each job on the system is uniquely identified by a job number.

Job/Session Number

A job/session number uniquely identifies either a job or session.

Job State

A generic term used for the stages that a job or session might pass through during its lifespan.

L

Limit

The limit is the lowest priority (highest numeric value) of processes within that workgroup (LIMIT=value). Values can range between the priority values of 150 and 255. Internally the priorities range from 32767 to 0. AIFSCGET/PUT return or modify internal priorities. Process priorities within the workgroup will not decay beyond the limit. If the boost property for the workgroup is oscillate, process priorities will be reset to the base value once they decay to the limit. The limit is a required workgroup characteristic.

Linked Spoolfile

A linked spoolfile has an entry in the SPFDIR and resides in the HPSPOOL account. Input spoolfiles reside in @.IN.HPSPOOL. Output spoolfiles reside in @.OUT.HPSPOOL. If a user copies a spoolfile from OUT.HPSPOOL to his or her local group and account, the copy has no entry in the SPFDIR and is therefore not a linked spoolfile. Refer to the spooler management routine AIFSpoolfLink for further information.

Logon

Logon is the job/session, user and account name associated with a process. The logon of a process can change dynamically through AIFCHANGELOGON. Logon is one of the process attributes used to determine workgroup membership. Therefore, a change in logon may result in an immediate change in workgroup assignment.

M

Mail Slot

The front panel storage slot used to insert or remove Magneto-Optical Media in an optical disk library system.

Maximum CPU Percentage

The maximum CPU percentage is a upper bound for the amount of CPU the processes in a workgroup can consume relative to other workgroups. The maximum CPU percentage value can be used to limit the amount of CPU consumed by a workgroup. This control may result in the system idling if the workgroup hits its maximum percentage and there are no other users who want the CPU. The default value is 100%.

Maximum Quantum

The maximum quantum is an upper bound for the dynamically calculated quantum ( average transaction time ) value for that workgroup ( MAXQUANT=Value ). Values range between 0 and 32767. The maximum quantum is an optional workgroup characteristic with a default value of 1000.

Media Label

A record defining the label for Magneto-Optical Media which consists of three parts including media_name, subname1, and subname2.

Media Name

A packed array of 1 to 32 characters used to identify the first part of the media label.

Media Slot

A number specifying a Magneto-Optical disk library system media storage slot.

Membership Criteria

The membership criteria of a workgroup is composed of a number of category specifications. Three categories are currently supported ( logon, program, and scheduling queue ). For a given workgroup, at least one category must be specified. If multiple specifications are specified, a process must match one specification from each category. Categories not specified take their default values.

The following table lists the default values for the membership criteria:

Table D-1 Membership Criteria Default Values

Membership Criteria	Default Values
Logon	@,@.@ (any jobname,user.account)
Program	@.@.@ (any program)
Scheduling Queue	AS, BS, CS, DS, ES (any queue)

Message

The Message is the portion of the overall package handled internally by the AIF Ports code that is delivered to the receiver process. It is the data that is "sent."

Message File

A message file acts as a first-in-first-out queue of records, with entries made by FWRITE and deletions made by FREAD. These are often used for interprocess communication by having one process submit records while another process removes them.

Minimum CPU Percentage

The minimum CPU percentage is a lower bound for the amount of CPU the processes in a workgroup can consume relative to other workgroups. The minimum CPU percentage value can be used to guarantee a certain amount of CPU to a workgroup. Note that the CPU consumption of the workgroup may not precisely match the specified minimum CPU percentage if there is insufficient demand within the workgroup. The default value is 0%.

Minimum Quantum

The minimum quantum is a lower bound for the dynamically calculated quantum ( average transaction time ) value for that workgroup ( MINQUANT=Value ). Values range between 0 and 32767. The mimimum quantum is an optional workgroup characteristic with a default value of 1 for user workgroups and CS_Default workgroup. The default value for DS_Default and ES_Default is 2000.

MPE file

The term MPE file refers to a file that can be represented using MPE semantics (for example, CI.PUB.SYS).

N

Natural Member

A process becomes a natural member of a workgroup when it is placed into the workgroup via the system. The system will scan the ordered list of workgroups, selecting the first workgroup whose membership criteria match the process' attribute.

NM Files

The MPE/iX file system currently consists partially of NM files and CM files. Consequently, CM code handles certain types of files after switching to CM. Files that do not require switching to CM are called NM files.

NMS

NMS is an abbreviation for the Native Mode Spooler. This new MPE/iX native mode spooler replaces the previous CM SPOOLER and SPOOK.

P

pathname

A pathname specifies where a particular file or directory is within the directory structure; that is what path the system must take when traversing the directory. See also absolute pathname and relative pathname.

PID

PID is an abbreviation for Process ID. Just as every process is assigned a PIN #, in MPE/iX every process is also assigned a PID. The PID is a 64-bit long integer comprised of the machine #, the PIN #, and a reuse counter.

PIN

PIN is an abbreviation for Process Identification Number. In MPE/iX every process is assigned a PIN #. The PIN is a 16-bit short integer.

Port

A Port refers to the collection of data structures managed by the AIF Ports procedures. It provides a level of abstraction when sending a message form one process to another. The sending process does not need to be explicitly aware of exactly which process reads the message; it simply sends a message to a given Port knowing that some process will eventually read it. Likewise, the receiver does not necessarily need to know which process sent it a message; the receiver only needs to know that the message came from a given Port. A message is considered to pass through a Port during the send/receive cycle.

Port Manager

As part of the feature set provided with the AIF Ports facility, a process can be designated as the Port Manager for the Port. When a Port Manager is not involved in the message transfer, the AIF Ports code prioritizes a message from the sender along with any previously sent but unreceived messages, then signals a receiver process ready for another message that a message is available. When a Port Manager process is involved, the AIF Ports code simply stores the message from the sender in the Port data structures, then sends the envelope portion of the message to the Port Manager so it can assume processing of the message.

Port Name

A Port name is a name given to a Port, which can consist of from 1 to 16 characters and can contain any characters. The name is upshifted before use.

Port Password

A Port password is a password to be associated with a Port. The process that creates a Port establishes the Port password. All subsequent opens must use the same password.

POSIX

Portable Operating System Interface. A set of standards that address various areas of operating system technology. The POSIX standards describe functions of an operating system interface that applications use to become POSIX-compliant. The main point of POSIX is to facilitate software portability and minimize porting costs.

Priority Boost

A priority boost raises the priority of a process. This occurs at the end of a transaction when a process holds a resource that a higher priority process needs, when a process has a stalled transaction, or when Break or Ctrl-Y must be processed.

Private Spoolfile

A private spoolfile is HPFOPENed with the PRIVATE option. Under NMS all input spoolfiles are private spoolfiles, and a user can designate output spoolfiles private for security purposes. Refer to the NMS manual for further information on private spoolfiles.

Process-specific File

The same physical file maybe opened more than once by the same process. Some of the file context is common for all the OPENs issued by a process against a physical file. This kind of information is referred to as process-specific information.

Program File

The name of the program file that is currently loaded for execution by the process. This name may change if the process makes use of the POSIX exec system call. The program file is one of the process attributes used to determine the workgroup membership. Therefore, changing the program file may result in an immediate change in workgroup assignment.

R

Receiver Process

The receiver process is the complement to a sender process. If one process is sends messages, the receiver process reads these messages.

Record Pointer

The file system maintains information about where the user is located in the file (what the next read fetches and where the next write is dispatched). The record pointer, the record number, and the offset within the record all provide the complete context. When a record pointer is shared, all three are shared.

Relative Pathname

A pathname that is interpreted from the current working directory. For example, ./dir1/longfilename refers to the file longfilename in directory dir1 in the current working directory.

Return_array

The system-wide interface returns values in arrays of this type. The actual structure of the array varies depending on the type of keys passed, but the general form is: Array [1..x] of appropriate type. x represents any integer and appropriate type is specified in AIFSysWideGet.

S

Scheduling Characteristics

The scheduling characteristics of the workgroup determine the scheduling policies which govern the processes within that workgroup. The base and limit priorities determine the range of the priority values for processes within the workgroup, while the quantum bounds define the range over which the quantum can change. The timeslice and boost property values also determine the scheduling behavior. The other scheduling characteristic is CPU Percentage bounds.

The following table lists the default values for the scheduling characteristics:

Table D-2 Scheduling Characteristics Default Values

Scheduling Characteristics	Default Values
Boost Property	Decay
Minimum CPU Percentage	0%
Minimum Quantum	1 (2000 for DS_Default and ES_Default)
Maximum CPU Percentage	100%
Maximum Quantum	2000
Timeslice	200 (1000 for AS_Default and BS_Default)

Scheduling Queue

In the current implementation, scheduling queue can mean one of two things. First, a scheduling queue is a process attribute that can be set by the user (e.g., :RUN foo;PRI=BS). This attribute can also be changed dynamically through :ALTPROC, the intrinsic GETPRIORITY, or the AIF, AIFPROCPUT. Second, scheduling queue refers to a collection of processes with similar scheduling characteristics. MPE/iX currently supports five queues. The AS and BS queues are typically used for system processes, the CS queue is typically used for interactive users, while the DS and ES queues are typically used for batch jobs.

Scheduling queue, as a process attribute, is an integral part of the workgroup concept. This is one of the process attributes used to determine workgroup membership. Because of its dynamic nature, a change in the process' queue attribute results in an immediate change in the process' workgroup assignment.

Search_key

The system-wide interface returns arrays of keys. The number of keys returned in a call depends on the space that you allocate. If more keys can be returned then this is indicated in the status, a special key is returned that can be used in a subsequent call to AIFSysWideGet to start the scan from that search key without repeating the keys returned before. The search key should be defined as array [1..48] of char.

Sender Process

The sender process, sometimes referred to as the sender, enables a message to be sent and received by another process.

Session

A session is an interactive dialog between the user and the computer. Each session on the system is uniquely identified by a session number.

SPFDIR

This is an abbreviation for spoolfile directory, which is the table that the NMS uses to maintain information about spoolfiles.

SPIT

This is an abbreviation for the Spooling Process Information Table, which is the table that NMS uses to maintain information about spooling processes.

Spoolfile

The spoolfiles generated by the file system for the NMS are ordinary disc files. This prevents input and output spoolfiles from being lost during system boots as they currently are. A new file type identifies the files as spoolfiles and allows them to be managed in this manner.

Two new file codes have also been assigned: 1515 for input spoolfiles and 1516 for output spoolfiles. Input spoolfiles are created in the IN group of the reserved account HPSPOOL, and output spoolfiles are created in the OUT group of the HPSPOOL account.

Streams LDEV

The streams LDEV is the device specified with the Streams command to be used as the input device for all jobs on the system. This device should not actually exist, as it is a 'pseudo-device' that must be configured with the device class JOBTAPE.

Subname1

A packed array of 1 to 16 characters used to identify the second part of the media label.

Subname2

A packed array of 1 to 16 characters used to identify the third part of the media label.

Surface

A number of either 0 or 1. The number zero specifies the "A" side of a Magneto-Optical Media and the number one specifies the "B" side. Sometimes referred to as "side".

System Average Quantum (SAQ)

System Average Quantum determines how rapidly process priorities decay. There are different SAQs for the CS, DS and ES queues. Within the CS queue, the SAQ is adjusted as processes complete transactions and represents the average transaction time of processes in the CS queue. The SAQ for the DS and the ES queues is a user-configurable value chosen to represent the average transaction time of these queues.

System Logging

System logging is a facility that records the occurrence of specific events and system resource usage into the system log files on a job/session basis. The system manager can enable or disable system logging types.

System Process

A system process is one that is a child of PROGEN or has inherited system process status from its parent. By definition, a system process executes with a non-decayable (linear) priority. However, a process does not need to be a system process to have a non-decayable priority. Process Management considers a system process an integral part of the OS and will abort the system if a system process dies.

T

Timeslice

The timeslice is the maximum number of milliseconds a process in that workgroup can hold the CPU before returning to the Scheduler to have its priority recalculated (TIMESLICE=value). Values must be multiples of 100, with a minimum value of 100 and a maximum value of 32700. The timeslice is an optional workgroup characteristic with a default value 200 milliseconds for CS_Default, DS_Default, ES_Default and user-defined workgroups. The default value for AS_Default and BS_Default workgroups is 1000.

Transaction

A transaction is comprised of a series of events. Most commonly, a transaction is the action performed between terminal read waits. A transaction is also considered complete when a process pauses at length (more than two seconds), blocks on a call to IO_Wait, or blocks waiting for IPC.

U

UFID

UFID is an abbreviation for for Unique File Identifier. It is a unique name to a single file throughout the life of a system. It is unique even across system boots.

User Files

The files opened for a particular user could have been opened either by an explicit OPEN (FOPEN or HPFOPEN) by the user program, or by the system on behalf of the user. The files opened explicitly are called user files and the remainder are non-user files. This procedure can be used to modify the information about user files only.

W

Workgroup

A workgroup is a collection of processes with identical scheduling characteristics. The scheduling characteristics include base and limit priority, timeslice value, boost property, etc.

Workgroup membership is determined by matching specific process attributes against a set of predefined membership criteria. The process attributes selected include logon, program file, profile, and scheduling queue.

Workgroup membership criteria and scheduling characteristics are determined by the System Manager.