Visual DataFlex: Difference between revisions

Revision as of 17:12, 13 August 2014

Revision as of 19:09, 15 September 2014

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'''Visual DataFlex''' ishas abeen [[4GL]]re-branded windowsas '''[[programming languageDataFlex]]''' by [[Data Access Worldwide (company)|Data Access Worldwide]] as of the release of version 2014/18.0 in August, targeted2014. atThe rapidlylatest creatinginformation about the product is consolidated in the [[databaseDataFlex]] and client-server type programsarticle.

Visual DataFlex is a [[4GL]] [[programming language]] and IDE/Studio targeted at application developers needing to rapidly create Windows client-server and web [[database]] business applications.

== Architecture ==

Visual DataFlex has a 3-layer architecture:

Visual DataFlex’s [[Multitier_architecture|multi-tier (N-tier) application architecture]] provides a well-defined structure for developers to create Windows and Web applications, Web Services and [[Service-oriented_architecture|Service Oriented Architectures (SOA)]].

;Bottom layer: At this level you have the database tables.

===Database Tier===

;Middle layer: Here you have Data Dictionary classes which are the core of the product. Data Dictionaries define the business rules for each table in your database. For example, when orders are saved a customer's balance can be adjusted and the balance tested against the customer's credit limit. An error can be raised if the customer's balance would exceed the allowable credit limit. Rules for saving, editing, deleting, or finding records are defined too. For example, you may not be allowed to delete an inventory item because there is history for it i.e. there are sales or purchases of the item. Finding of certain records can be limited to users who have the required credentials.

Visual DataFlex’s architecture abstracts the database tier enabling the interchangeable use of different SQL databases such as Microsoft SQL Server, IBM DB2, Pervasive PSQL, Oracle, and ODBC data sources, or the embedded DataFlex database.

===Database Rules & Application Logic Tier===

;Top layer: A graphical user interface ([[GUI]]) that allows users to enter, find, create, modify, or delete data. The UI will respect all of the business rules defined in the Data Dictionary classes.

In Visual DataFlex, an application’s database and business rules are defined in and managed by "Data Dictionaries." Data Dictionaries are a middle tier between the application’s database and user interface that:

* Provide applications with a extended, application-specific information that is not part of the physical database. It extends the database.

== History ==

* Protect the data – Data Dictionaries define and validate allowable data additions and updates.

* Reduce programming errors and maintenance by centralizing an application’s business logic. All information and rules about a database and how it is managed is stored in one place - the Data Dictionary. If a developer needs to make an application logic change, it is made in the Data Dictionary and all parts of the application, regardless of user interface, acquire the change.

===User Interface Tier===

Data Access Worldwide of Miami, USA, developed the language having built its business up around the console mode [[DataFlex]] language which was released prior to [[MS-DOS|DOS]] and competed with [[dBase|dBase II]] in early microcomputer technology. The first attempt at a windows product was ''DataFlex for Windows'' which failed as it was a sort of windows bolted on top of DOS product. Then they released Visual DataFlex 4.0 in 1997 which allowed users to write native 32 bits Windows applications. Every 6 months a new revision level is released. Visual DataFlex is now in revision 18.0, named DataFlex 2014,<ref>{{cite web|url=http://www.visualdataflex.com/features.asp?pageid=1073|title=Visual DataFlex Features-Visual DataFlex 2014/18.0 |publisher=Visualdataflex.com |date= |accessdate=2012-07-05}}</ref> and features a datadictionary layer of business rules which is of dual use with the windows product and the webapp extension.

Visual DataFlex user interfaces can be developed for Windows desktop, Web browser and mobile environments. Similarly structured user interface frameworks for Windows and web connect to Data Dictionaries to complete the application stack.

== History ==

With version 18.0 in 2014 the company re-branded the product to "DataFlex" with several product families under the same brand.

[[Data Access Worldwide (company)|Data Access Worldwide]] of Miami, USA is the developer and publisher of the Visual DataFlex software suite and language. The company originally started with the character-based application development environment for early DOS and multi-user networks. The first Windows product was DataFlex for Windows, which was followed by Visual DataFlex 4.0 in 1997. Since then, Visual DataFlex has been enhanced through numerous revisions and platform expansions including browser-based web applications that offer functionality similar to Windows desktop applications. With version 18.0's release in 2014, the company re-branded the product to "DataFlex" with several product families under the same brand. Data Access Worldwide’s software development teams are based in Miami, Florida U.S.A. and Hengelo, The Netherlands.

== References ==

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== External links ==

* [http://www.visual-dataflexdataaccess.com/dataflex/ Latest DataFlex OfficialProduct websiteInformation]

* [http://support.dataaccess.com/forums/ Support forumForums]

* [http://support.dataaccess.com/Forums/blog.php DataFlex Development Team Blog]

* [http://www.visualdataflex.com Visual DataFlex product website (deprecated as of August, 2014)]

* [http://www.vdfwiki.com vdfwiki.com]

* [http://support.dataaccess.com/forums/ Support forum]

* [http://www.vdf-guidance.com Visual DataFlex open source website]

* [http://www.visual-dataflex.co.uk Asckey Data Services UK Channel Partners]

[[Category:4GLDesktop_database_application_development_tools]]

[[Category:4GL]]

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