Skip to main content
Version: v19

Architecture of a project

A 4D project is made of several folders and files, stored within a single project root folder (package folder). For example:

  • MyPackage (project root folder)
    • Components
    • Data
      • Logs
      • Settings
    • Documentation
    • Plugins
    • Project
      • DerivedData
      • Sources
      • Trash
    • Resources
    • Settings
    • userPreferences.username
    • WebFolder

If your project has been converted from a binary database, additional folders may be present. See "Converting databases to projects" on

Project folder

The Project folder typically contains the following hierarchy:

  • applicationName.4DProject file
  • Sources
    • Classes
    • DatabaseMethods
    • Methods
    • Forms
    • TableForms
    • Triggers
  • DerivedData
  • Trash (if any)

applicationName.4DProject file

Project development file, used to designate and launch the project. This file can be opened by:

In 4D projects, development is done with 4D and multi-user development is managed through source control tools. 4D Server can open .4DProject files for testing purposes.

Sources folder

catalog.4DCatalogTable and field definitionsXML
folders.jsonExplorer folder definitionsJSON
menus.jsonMenu definitionsJSON
settings.4DSettingsStructure database settings. They are not taken into account if user settings or user settings for data are defined.Warning: In compiled applications, structure settings are stored in the .4dz file (read-only). For deployment needs, it is necessary to use user settings or user settings for data to define custom settings.XML
tips.jsonDefined tipsJSON
lists.jsonDefined listsJSON
filters.jsonDefined filtersJSON
styleSheets.cssCSS style sheetsCSS
styleSheets_mac.cssMac css style sheets (from converted binary database)CSS
styleSheets_windows.cssWindows css style sheets (from converted binary database)CSS

DatabaseMethods folder

databaseMethodName.4dmDatabase methods defined in the project. One file per database methodtext

Methods folder

methodName.4dmProject methods defined in the project. One file per methodtext

Classes folder

className.4dmUser class definition method, allowing to instantiate specific objects. One file per class, the name of the file is the class nametext

Forms folder

formName/form.4DFormProject form descriptionjson
formName/method.4dmProject form methodtext
formName/Images/pictureNameProject form static picturepicture
formName/ObjectMethods/objectName.4dmObject methods. One file per object methodtext

TableForms folder

n/Input/formName/form.4DFormInput table form description (n is the table number)json
n/Input/formName/Images/pictureNameInput table form static picturespicture
n/Input/formName/method.4dmInput table form methodtext
n/Input/formName/ObjectMethods/objectName.4dmInput form object methods. One file per object methodtext
n/Output/formName/form.4DFormOutput table form description (n is the table number)json
n/Output/formName/Images/pictureNameOutput table form static picturespicture
n/Output/formName/method.4dmOutput table form methodtext
n/Output/formName/ObjectMethods/objectName.4dmOutput form object methods. One file per object methodtext

Triggers folder

table_n.4dmTrigger methods defined in the project. One trigger file per table (n is the table number)text

Note: The .4dm file extension is a text-based file format, containing the code of a 4D method. It is compliant with source control tools.

Trash folder

The Trash folder contains methods and forms that were deleted from the project (if any). It can contain the following folders:

  • Methods
  • Forms
  • TableForms

Within these folders, deleted element names are in parentheses, e.g. "(myMethod).4dm". The folder organization is identical to the Sources folder.

DerivedData folder

The DerivedData folder contains cached data used internally by 4D to optimize processing. It is automatically created or recreated when necessary. You can ignore this folder.

Libraries folder

This folder is used on macOS only.

The Librairies folder contains the file resulting from a compilation with the Silicon compiler on macOS.

Resources folder

The Resources folder contains any custom project resource files and folders. In this folder, you can place all the files needed for the translation or customization of the application interface (picture files, text files, XLIFF files, etc.). 4D uses automatic mechanisms to work with the contents of this folder, in particular for the handling of XLIFF files and static pictures. For using in remote mode, the Resources folder lets you share files between the server machine and all the client machines. See the 4D Server Reference Manual.

itemProject resource files and foldersvarious
Images/Library/itemPictures from the Picture Library as separate files(*). Names of these items become file names. If a duplicate exists, a number is added to the name.picture

(*) only if the project was exported from a .4db binary database.

Data folder

The data folder contains the data file and all files and folders relating to the data.

data.4dd(*)Data file containing data entered in the records and all the data belonging to the records. When you open a 4D project, the application opens the current data file by default. If you change the name or location of this file, the Open data file dialog box will then appear so that you can select the data file to use or create a new onebinary
data.journalCreated only when the database uses a log file. The log file is used to ensure the security of the data between backups. All operations carried out on the data are recorded sequentially in this file. Therefore, each operation on the data causes two simultaneous actions: the first on the data (the statement is executed normally) and the second in the log file (a description of the operation is recorded). The log file is constructed independently, without disturbing or slowing down the user’s work. A database can only work with a single log file at a time. The log file records operations such as additions, modifications or deletions of records, transactions, etc. It is generated by default when a database is created.binary
data.match(internal) UUID matching table numberXML

(*) When the project is created from a .4db binary database, the data file is left untouched. Thus, it can be named differently and placed in another location.

Settings folder

This folder contains user settings files for data used for application administration.

These settings take priority over user settings files and structure settings files.

directory.jsonDescription of 4D groups, users, and their access rights when the application is run with this data file.JSON
Backup.4DSettingsDatabase backup settings, used to set the backup options when the database is run with this data file. Keys concerning backup configuration are described in the 4D XML Keys Backup manual.XML
settings.4DSettingsCustom database settings for this data file.XML

Logs folder

The Logs folder contains all log files used by the project. Log files include, in particular:

  • database conversion,
  • web server requests,
  • backup/restore activities journal (Backup Journal[xxx].txt, see Backup journal)
  • command debugging,
  • 4D Server requests (generated on client machines and on the server).

An additional Logs folder is available in the system user preferences folder (active 4D folder, see Get 4D folder command) for maintenance log files and in cases where data folder is read-only.

Settings folder

This folder contains user settings files used for application administration.

These settings take priority over structure settings files. However, if a user settings file for data exists, it takes priority over user settings file.

directory.jsonDescription of 4D groups and users for the application, as well as their access rightsJSON
Backup.4DSettingsDatabase backup settings, used to set the backup options) when each backup is launched. This file can also be used to read or set additional options, such as the amount of information stored in the backup journal. Keys concerning backup configuration are described in the 4D XML Keys Backup manual.XML
BuildApp.4DSettingsBuild settings file, created automatically when using the application builder dialog box or the BUILD APPLICATION commandXML

userPreferences.userName folder

This folder contains files that memorize user configurations, e.g. break point or window positions. You can just ignore this folder. It contains for example:

methodPreferences.jsonCurrent user method editor preferencesJSON
methodWindowPositions.jsonCurrent user window positions for methodsJSON
formWindowPositions.jsonCurrent user window positions for formsJSON
workspace.jsonList of opened windows; on macOS, order of tab windowsJSON
debuggerCatches.jsonCaught calls to commandsJSON
recentTables.jsonOrdered list of tablesJSON
preferences.4DPreferencesCurrent data path and main window positionsXML
CompilerIntermediateFilesIntermediate files resulting from Apple Silicon compilationFolder

Components folder

This folder contains the components to be available in the application project. It must be stored at the same level as the Project folder.

An application project can be used itself as a component:

  • for development: put an alias of the .4dproject file in the Components folder of the host project.
  • for deployment: build the component and put the resulting .4dz file in a .4dbase folder in the Components folder of the host application.

Plugins folder

This folder contains the plug-ins to be available in the application project. It must be stored at the same level as the Project folder.

Documentation folder

This folder contains all documentation files (.md) created for the project elements such as classes, methods, or forms. Documentation files are managed and displayed in the 4D Explorer.

For more information, refer to Documenting a project.


Defaut root folder of the 4D Web server for pages, pictures, etc. It is automatically created when the Web server is launched for the first time.