Glossary

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Alphabetical Index

A

B

C

D

E

F

G

H

I - N

O

P

Q

R

S

T

U

V

W

X Y Z

Glossary

A

Application

MIDAS Applications are programs provided by the MIDAS system to perform various functions e.g. data logging, web server etc. They run as MIDAS #Clients.

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B

Buffer

MIDAS maintains buffers (i.e. #Shared Memory) for ODB, System Messages, Data, Alarms and History system information. These buffers are managed by the Buffer Manager.

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C

Client

A MIDAS Client is an #Application provided by the MIDAS system or (partially) written by the user (e.g. a #Frontend) that links with the MIDAS libraries and runs under the MIDAS system to allow the user to run a MIDAS #Experiment. MIDAS clients can be Local or Remote.

Local

A MIDAS client than runs on the Experiment Host.

Remote

A MIDAS client than runs on a Remote Host.

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D

Data Bank

data in an event in a particular format

Device

a Hardware module (e.g. a scaler) to be accessed by software called a device driver.

Driver

(also device driver). Software that allows access to a particular hardware module.

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E

Environment Variables

Certain Environment Variables are used by MIDAS. Only MIDASSYS is required.

Equipment

usually Software equipment

Hardware

Hardware Devices (e.g. a set of scalers) grouped together for convenience of data readout by a Software Equipment.

Software

usually called "Equipment". A single or a collection of sub-tasks meant to collect and regroup logical or physical data (read from a Hardware Equipment) under a single and uniquely identified event. Software Equipments are usually found in Frontends, and are reflected in the /Equipment ODB tree.

Event

a collection of data sent into the data stream by an Equipment, usually in the form of data banks.

Experiment

a MIDAS experiment defined on the Experiment Host. Optionally defined in the exptab file.

Host

see #Host

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F

Frontend

A MIDAS application built by the user which usually has access to hardware equipment in use by the experiment. Includes Frontend Code linked with a fixed framework mfe.c to form a Frontend.

Code

The frontend code is the user-written part of the frontend application (e.g. frontend.c) describing sequence of actions to acquire the hardware data. See Frontend above.

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H

History

The MIDAS History System records useful information in parallel with the data logging. This can be displayed graphically.

Host

Computer running MIDAS clients, usually #Experiment Host.

Experiment

the experiment host is the host computer on which the MIDAS experiment #Shared Memory resides.

Remote

a remote host is a host computer on which (remote) MIDAS client(s) run which connect to the MIDAS experiment on the Experiment Host. See Quickstart Linux to set up a remote host.

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O

ODB

The Online Data Base (ODB) contains all the information needed for an experiment. It can be accessed and/or edited using the ODB Page of the #Web Server or odbedit application.

Directory

The ODB is structured as a "directory". ODB Directory is used as alternative name for an ODB Tree.

Key

Data in the ODB are contained in Key/Data pairs in an ODB Tree or subtree. ODB Keys can be of various Types. In the Path /Logger/write data, the key is write data.

Type

ODB Key Types can be one of BYTE,CHAR,WORD,SHORT,DWORD,INT,BOOL,FLOAT,DOUBLE,STRING

Data

Data is contained in Key/Data pairs in the ODB. Use the #Web Server or odbedit application to view the Key/Data pairs.

Path

"address" used to access an ODB Key using the directory structure of the ODB, e.g. /Logger/write data. Upper/Lower Case is ignored.

Subdirectory

Alternative name to ODB Subtree used by some authors

Subtree

An ODB subtree starts at a lower level than an ODB Tree, e.g. /Experiment/Security subtree.

Tree

data in the ODB are structured in a tree form with each "directory" dealing with a specific section of the acquisition. An ODB Tree starts at the top level, e.g. /Equipment ODB tree.

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R

Remote host

see#Host

Run

A run starts when the MIDAS system receives a Start Transition , and continues until it receives a Stop transition

State

MIDAS defines three run states: Stopped, Paused and Running. See Run States and Transitions.

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S

Server

MIDAS

A remote procedure call (RPC) server mserver available for remote access to a MIDAS experiment.

Web

See #Web Server

Shared Memory

The MIDAS shared memory regions in RAM are called buffers, and managed by the MIDAS Buffer Manager. MIDAS uses shared memory for the ODB, System Messages, Data buffer, Alarms and History systems. The MIDAS shared memory saved files (.*.SHM) for an experiment reside on the Experiment host at the path given by the Environment Variable MIDASSYS.

State

See #Run State

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T

Task

a MIDAS client application. Task and Utility are used in this document as alternatives to Application by different authors.

Transition

A transition occurs when a MIDAS experiment changes from one run state to another. See Run States and Transitions.

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U

Utility

a MIDAS client application. Utility and Task are used in this document as alternatives to Application by different authors.

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W

Web Server

The MIDAS Web Server is the application mhttpd. It is accessible from a browser and is used to control and monitor a MIDAS experiment.