# 2 Usage

###
2.1 Overview

This document focuses on the graphical parts of the tool. The concepts are explained in the reference manual for the module reltool.

###
2.2 System window

The system window is started with the function reltool:start/1. At startup the tool will process all beam files and app files in order to find out dependencies between applications and their modules. Once all this information has been derived, it will be possible to explore the tool.

The system window consists of four main pages (tabs):

- Libraries
- System settings
- Applications
- Releases

Click on a name tag to display its page.

####
Libraries

On the library page it is possible to control which sources the tool will use. The page is organized as a tree which can be expanded and collapsed by clicking on the little symbol in the beginning of the expandable/collapsible lines.

The Root directory can be edited by selecting the line where the path of the root directory is displayed and clicking the right mouse button. Choose edit in the menu that pops up.

Library directories can be added, edited or deleted. This is done by selecting the line where the path to a library directory is displayed and clicking the right mouse button. Choose add, edit or delete in the menu that pops up. New library directories can also be added by selecting the line Library directories and clicking the right mouse button. Choose add in the menu that pops up.

Escript files can be added, edited or deleted. This is done by selecting the line where the path to an escript file is displayed and clicking the right mouse button. Choose add, edit or delete in the menu that pops up. New escripts can also be added by selecting the line Escript files and clicking the right mouse button. Choose add in the menu that pops up.

When libraries and escripts are expanded, the names of their contained applications will be displayed. Double click on an application name to launch an application window.

####
System settings

On the system settings page it is possible to control some global settings that are used as defaults for all applications. Set the Application inclusion policy to include to include all applications that are not explicitly excluded. See incl_cond (application inclusion) and mod_cond (module inclusion) in the reference manual for the module reltool for more info.

The system settings page is rather incomplete.

####
Applications

There are four categories of applications on the applications page. Included contains applications that are explicitly included. Excluded contains applications that are explicitly excluded. Derived contains applications that either are used directly by explicitly included applications or by other derived applications. Available contains the remaining applications.

Select one or more applications and click on a button directly below the application column to change application category. For example, select an available application and click on its tick button to move the application to the included category. Clicking on the tick symbol for included applications will move the application back to the available category. The tick is undone.

The symbols in front of the application names are intended to describe the status of the application. There are error and warning symbols to signalize that there is something which needs attention. The tick symbol means that the application is included or derived and no problem has been detected. The cross symbol means that the application is excluded or available and no problem has been detected. Applications with error symbols are listed first in each category and are followed by the warnings and the normal ones (ticks and crosses) at the end.

Double click on an application to launch its application window.

####
Releases

The releases page is incomplete and very experimental.

####
File menu

- Display application dependency graph - Launches an application force graph window. All included and derived applications and their dependencies will be shown in a graph.

- Display module dependency graph - Launch a module force graph window. All included and derived modules and their dependencies will be shown in a graph.

- Reset configuration to default

- Undo configuration (toggle)

- Load configuration - Loads a new configuration from file.

- Save configuration - Saves the current configuration to file. Normally, only the explicit configuration parameters with values that differ from their defaults are saved. But the configuration with or without default values and with or without derived values may also be saved.

- Generate rel, script and boot files

- Generate target system

- Close - Close the system window and all its subwindows.

####
Dependencies between applications or modules displayed as a graph

The dependency graph windows are launched from the file menu in the system window. The graph depicts all included and derived applications/modules and their dependencies.

It is possible to perform some limited manipulations of the graph. Nodes can be moved, selected, locked or deleted. Move a single node or the entire graph by moving the mouse while the left mouse button is pressed. A node can be locked into a fix position by holding down the shift button when the left mouse button is released. Select several nodes by moving the mouse while the control key and the left mouse button are pressed. Selected nodes can be locked, unlocked or deleted by clicking on a suitable button.

The algorithm that is used to draw a graph with as few crossed links as possible is called force graph. A force graph consists of nodes and directed links between nodes. Each node is associated with a repulsive force that pushes nodes away from each other. This force can be adjusted with the left slider or with the mouse wheel. Each link is associated with an attractive force that pulls the nodes nearer to each other. This force can be adjusted with the right slider. If this force becomes too strong, the graph will be unstable. The third parameter that can be adjusted is the length of the links. It is adjusted with the middle slider.

The Freeze button starts/stops the redrawing of the graph. Reset moves the graph to the middle of the window and resets all graph settings to default, with the exception of deleted nodes.

###
2.3 Application window

The application window is started by double clicking on an application name. The application window consists of four pages (tabs):

- Application settings
- Modules
- Application dependencies
- Module dependencies

Click on a name tag to display its page.

####
Application settings

Select version of the application in the Source selection policy part of the page. By default the latest version of the application is selected, but it is possible to override this by explicitly selecting another version.

Note that in order for reltool to sort application versions and thereby be able to select the latest, it is required that the version id for the application consists of integers and dots only, for example 1, 2.0 or 3.17.1.

By default the Application inclusion policy on system level is used for all applications. Set the value to include if you want to explicitly include one particular application. Set it to exclude if you want to exclude the application despite that it is used by another (explicitly or implicitly) included application. derived means that the application automatically will be included if some other (explicitly or implicitly) included application uses it.

By default the Module inclusion policy on system level is used for all applications. Set it to derived if you only want actually used modules to be included. Set it to app if you, besides derived modules, also want the modules listed in the app file to be included. Set it to ebin if you, besides derived modules, also want the modules that exist as beam files in the ebin directory to be included. Set it to all if you want all modules to be included, that is the union of modules found in the ebin directory and listed in the app file.

The application settings page is rather incomplete.

####
Modules

There are four categories of modules on the modules page. Included contains modules that are explicitly included. Excluded contains modules that are explicitly excluded. Derived contains modules that either are used directly by explicitly included modules or by other derived modules. Available contains the remaining modules.

Select one or more modules and click on a button directly below the module column to change module category. For example, select an available module and click on its tick button to move the module to the included category. Clicking on the tick symbol for included modules will move the module back to the available category. The tick is undone.

The symbols in front of the module names are intended to describe the status of the module. There are error and and warning symbols to signalize that there is something that needs attention. The tick symbol means that the module is included or derived and no problem has been detected. The cross symbol means that the module is excluded or available and no problem has been detected. Modules with error symbols are listed first in each category and are followed by warnings and the normal ones (ticks and crosses) at the end.

Double click on a module to launch its module window.

####
Application dependencies

There are four categories of applications on the Application dependencies page. If the application is used by other applications, these are listed under Used by. If the application requires other applications be started before it can be started, these are listed under Required. These applications are listed in the applications part of the app file. If the application includes other applications, these are listed under Included. These applications are listed in the included_applications part of the app file. If the application uses other applications, these are listed under Uses.

Double click on an application name to launch an application window.

####
Module dependencies

There are two categories of modules on the Module dependencies page. If the module is used by other modules, these are listed under Modules using this. If the module uses other modules, these are listed under Used modules.

Double click on an module name to launch a module window.

###
2.4 Module window

The module window is started by double clicking on an module name. The module window consists initially of two pages (tabs):

- Dependencies
- Code

Click on a name tag to display its page.

####
Dependencies

There are two categories of modules on the Dependencies page. If the module is used by other modules, these are listed under Modules using this. If the module uses other modules, these are listed under Used modules.

Double click on an module name to launch a module window.

####
Code

On the Code page the Erlang source code is displayed. It is possible to search forwards and backwards for text in the module. Enter a regular expression in the Find field and press enter. It is also possible to go to a certain line in the module. The Back button can be used to go back to the previous position.

Put the marker on a function name and double click to go to the definition of the function. If the function is defined in another module, that module will be loaded and added to the page list.