Editing Data dictionary (section)

==Middleware==
In the construction of database applications, it can be useful to introduce an additional layer of data dictionary software, i.e. [[middleware]], which communicates with the underlying DBMS data dictionary. Such a "high-level" data dictionary may offer additional features and a degree of flexibility that goes beyond the limitations of the native "low-level" data dictionary, whose primary purpose is to support the basic functions of the DBMS, not the requirements of a typical application. For example, a high-level data dictionary can provide alternative [[entity-relationship model]]s tailored to suit different applications that share a common database.<ref>U.S. Patent 4774661, [http://www.freepatentsonline.com/4774661.html Database management system with active data dictionary], 19 November 1985, AT&T</ref> Extensions to the data dictionary also can assist in [[query optimization]] against [[distributed database]]s.<ref>U.S. Patent 4769772, [http://www.freepatentsonline.com/4769772.html Automated query optimization method using both global and parallel local optimizations for materialization access planning for distributed databases], 28 February 1985, Honeywell Bull</ref> Additionally, DBA functions are often automated using restructuring tools that are tightly coupled to an active data dictionary.

[[Software framework]]s aimed at [[rapid application development]] sometimes include high-level data dictionary facilities, which can substantially reduce the amount of programming required to build [[Menu (computing)|menus]], [[Form (programming)|forms]], reports, and other components of a database application, including the database itself. For example, PHPLens includes a [[PHP]] [[class library]] to automate the creation of tables, indexes, and [[foreign key]] constraints [[Portability (software)|portably]] for multiple databases.<ref>PHPLens, [http://phplens.com/lens/adodb/docs-datadict.htm ADOdb Data Dictionary Library for PHP] {{Webarchive|url=https://web.archive.org/web/20071107170943/http://www.phplens.com/lens/adodb/docs-datadict.htm |date=7 November 2007 }}</ref> Another PHP-based data dictionary, part of the RADICORE toolkit, automatically generates program [[Object (computer science)|objects]], [[Scripting language|scripts]], and SQL code for menus and forms with [[data validation]] and complex [[join (SQL)|joins]].<ref>RADICORE, [http://www.radicore.org/viewarticle.php?article_id=5 What is a Data Dictionary?]</ref> For the [[ASP.NET]] environment, [[Base One International|Base One's]] data dictionary provides cross-DBMS facilities for automated database creation, data validation, performance enhancement ([[Cache (computing)|caching]] and index utilization), [[application security]], and extended [[data type]]s.<ref>Base One International Corp., [http://www.boic.com/b1ddic.htm Base One Data Dictionary]</ref> [[Visual DataFlex]] features<ref>VISUAL DATAFLEX,[http://www.visualdataflex.com/features.asp?pageid=1030 features] {{Webarchive|url=https://web.archive.org/web/20180405135738/http://www.visualdataflex.com/features.asp?pageid=1030 |date=5 April 2018 }}</ref> provides the ability to use DataDictionaries as class files to form middle layer between the user interface and the underlying database.   The intent is to create standardized rules to maintain data integrity and enforce business rules throughout one or more related applications.

Some industries use generalized data dictionaries as technical standards to ensure interoperability between systems. The real estate industry, for example, abides by a [https://ddwiki.reso.org RESO's Data Dictionary] to which the [[National Association of Realtors|National Association of REALTORS]] mandates<ref>{{Cite web|title=Real Estate Transaction Standards (RETS) Web API|url=https://www.nar.realtor/about-nar/policies/mls-policy/real-estate-transaction-standards-rets-web-api|access-date=2020-10-11|website=nar.realtor|date=23 January 2015 |language=en}}</ref> its [[Multiple listing service|MLSs]] comply with through its policy handbook.<ref>{{Cite web|title=Handbook on Multiple Listing Policy|url=https://www.nar.realtor/handbook-on-multiple-listing-policy|access-date=2020-10-11|website=nar.realtor|date=January 2015 |language=en}}</ref> This intermediate mapping layer for MLSs' native databases is supported by software companies which provide API services to MLS organizations.