DirList2ODBC - Terminology

 

Term Definition
Administrative access When you have administrative access, which is when your user has CanViewHiddenEntries in tblUser enabled and ADMINMODE is currently set to 1, you can view and modify users in tblDirEntry who have the Exclude flag set.  Be sure you read the section on the ADMINMODE statement for enabling and disabling the administrative mode on a recordset.
Auditing E-mails an administrator when users perform audited operations in the DirList2 database.
Base directory A directory on the system that contains home directories of users. DirList2 Server scans a defined base directory for user's home directories and builds its index files from it.
Catalog function Catalog functions give ODBC clients information about the data types and table definitions for the data that the driver handles.   The DirList2ODBC driver implements every catalog function in the ODBC 2.0 specification except for SQLColumnPrivileges, SQLProcedureColumns, SQLProcedures, and SQLTablePrivileges.
CGI Common Gateway Interface.  A CGI program runs under a web server when requested from a web client such as a browser.  The client sends a request to a resource on the server, typically a GET or a POST, and that resource, if a CGI program, will be run on the web server.  The CGI program reads the input, processes it, and returns the result to the web server, which then returns that response to the original web client.
Classification data See extended data.
Connection pooling When enabled, connections that are freed by an ODBC client will not be freed in the actual driver if an ODBC client requests the same type of connection within the pooling timeout.  If this does not happen, however, the ODBC Driver Manager will free the connection in the driver.  In some environments, such as in ASP and PHP web pages, connections are typically created and freed in a short window, and if many people are hitting the site in a small time window, connection pooling can save time by "recycling" active connections for new connection requests.
Database A dynamic collection of tables and their fields.  A database can be modified and changed at will, and data can be extracted from one or more tables with user-defined criteria, making a database quite flexible and powerful to users and programs alike.
DBMS Database Management System.  A DBMS is an implementation of a database.
DDL Database Design Language.  SQL functions that create, modify, and delete tables fit into this category.  DirList2ODBC does not support any DDL functions.  See also DML.
DML Database Manipulation Language.  SQL functions that store, manipulate, and retrieve data from tables fit into this category.  DirList2ODBC supports most DML functions to various extents.  See also DDL.
Directory entries Directory records associated with home directories on the host system.
DirList2 A specialized database system that allows easy presentation and administration of user information on a POSIX system.
DirList2ODBC The name of the driver that allows ODBC clients such as Access to use the DirList2 system as if it was a regular database system.
DirList2 Server An implementation of the DirList2 specification that allows presentation and administration through a web interface.  The server is actually a CGI program and thus has unique circumstances when compared to other DBMSes.
DSN Data Source Name.  In ODBC, each data source has a unique name in the system that, when used, allows the ODBC Driver Manager to lookup which driver to use, and from there the data source name tells the ODBC driver which settings to use such as how to connect to the DBMS and what parameters to use.
Extended data Data for fields that are not built into the standard directory entry fields.  Extended data types are defined as classifications (aka, "classes") in the DirList2 system.
Field A single item of data that represents some property of the table that it is in.  A field can have one of several data types.
Field qualification Specifying the table before a field is referred to as qualifying a field.  When the selected tables have fields with the same names, field qualification is required, but in other situations field qualification is optional.   In DirList2ODBC, field qualification might have slight performance benefits if you are querying data from many tables.  Otherwise, field qualification might actually waste a couple fractions of a millisecond.
Home directory A user's personal directory, usually a subdirectory under /home or C:\WinNT\Profiles. DirList2 Server scans a defined base directory for user directories and builds its index files from it.
Host system The system that DirList2 Server is running on.   This is usually a POSIX compliant system.
Index In DirList2, an index is the database file itself.  This is an "index" of the home directories on the host system, hence its name.  When specifying an index file as a parameter in the ODBC driver, you must leave out the directory and the .idx2 extension; the server automatically adds these.
Literal A literal, quite "literally," is a value.  As an example, "Hi" would qualify as a literal as would the number 25.  Conditions and field names, however, are not literals.   tblDirEntry.UserName would not qualify as a literal and neither would (UserName OR Exists).
Locking Grants exclusive access to a user in order to prevent others from modifying the database at the same time.
ODBC Open Database Connectivity.  This is an interface developed by Microsoft, X/Open, and others that allows applications to access diverse databases with a single, flexible interface.
ODBC client A program that uses ODBC to access databases.
ODBC driver An ODBC driver implements functions in the ODBC specification that are relevant to the DBMS that it is designed to speak with.  When these functions are used, the driver responds to the function calls by performing the requested operation(s) in the actual DBMS.   This usually involves establishing a connection to the DBMS and then exchanging data.  The driver in this program is called DirList2ODBC, and it allows ODBC clients to speak with DirList2 system.
ODBC Driver Manager When an ODBC client uses ODBC, it is actually speaking the the ODBC Driver Manager, whose job is to load the correct driver for a requested data source and forward function calls and results to and from the actual driver.  Some ODBC Driver Managers, such as Microsoft's implementation, can provide other services for a driver such as emulating cursors for drivers that do not support them.
POSIX Portable Operating System Interface.  This type of system is required for DirList2 Server to compile on.  Lookup POSIX on www.whatis.com for more information.
Primary key One or more fields in a table that uniquely identify a single row of data.
Recordset A table of fields and values usually generated from an ODBC operation that returns a recordset.  The SQL SELECT statement and the ODBC catalog functions return recordsets.
Sequence number Each time the index file is updated, whether it be a write or a delete to any of the tables, the sequence number in the header of the index file is incremented.  This allows programs such as the web interface to detect changes so that they can warn the user about stale search results and similar situations.
Signed value A number that can be negative.  The leftmost bit is used as an indicator of negation; 0 is positive and 1 is negative.   As a result of this situation, the highest positive number is cut in half (using integer division).  On the good side, however, the lowest value drops from zero to the negative value of half of the highest original positive number (using integer division), minus one.  See unsigned value for the opposite situation.
Sort table A sort table defines the orders that web queries can extract from the database.  For more information, view the server documentation.
SQL Structured Query Language.  This standardized database language allows users and programs to easily and powerfully store, manipulate, and retrieve data regardless of the underlying DBMS.
String Zero or more characters that are put together for a value.  As an example, this definition consists of a "string" of characters that, when together, create a value, which in our case is the definition for the term "string."  This is different from a number because strings typically have different lengths depending on how long the message is.  In contrast, numbers take up the same amount of space in a given numeric type regardless of the value, making numbers more convenient and faster for handling and storing numeric data.   STRING is also a data type used in DirList2ODBC.  Be sure you read the release note on string searches.
Table A collection of fields.   Note that this is not necessarily a sort table, which is something else.
Unsigned value A value that cannot be negative.  The highest value equals 2 raised to the number of bits in the number minus one.  The lowest value, obviously, is zero.  See signed value for the opposite situation.
Update an index Updating an index asks DirList2 Server to go through the directory specified by BaseDir in tblIndexInfo.   During this process, new entries are added to the database, non-existent users have their Exists flag in tblDirEntry set to false, and web directories, specified by WebDocsDir in tblIndexInfo, are poked for valid web sites for entries that have CheckWebSite set to true in tblDirEntry.
Web query When a user accesses DirList2 with a web browser, the server returns the values of the fields requested in addition to a HTML header and footer if present.

 

Copyright (c) 2000 Steven Lawrance
Copyright (c) 1999-2000 Bryant College
Written by Steven Lawrance
DirList2 Server Version: 2.6
DirList2ODBC Version: 1.51
Last Revision: 10-08-2000