The interface class for dynamically loaded plugins. More...

#include <VFS_node_interface.h>

Inheritance diagram for VFS_node_interface:

Public Member Functions
virtual	~VFS_node_interface ()

virtual QString	arguments (QString type)
	Describe the arguments needed to create a node. More...

virtual QString	code (QString nodename, QString libname, QString &error)
	Request code or other resource from a plugin bundle. More...

virtual VFS_node *	create (QString type, QVariantMap env, QDomElement child)
	Create a new node instance. More...

QString	describe ()
	Describe all the nodes in a plugin. More...

virtual QString	description (QString type)
	Descriptive text about an individual node. More...

virtual bool	initialize ()
	The plugin initializer. More...

bool	isRemote ()
	If a plugin represents a remote resource, this value will be true. More...

virtual bool	licensed (QString type)
	A licensing mechanism for node creation. More...

virtual QStringList	provides ()
	A string list of node names that this plugin is prepared to create. More...

VFS_node *	remoteNode ()
	Return the node needed to satisfy a remote request. More...

Protected Member Functions
	VFS_node_interface (VFS_node *remoteNode=nullptr)
	VFS_node_interface::VFS_node_interface. More...

QString	argumentString (QMetaObject s)
	Format a constructor string based on a node's metadata object. More...

Protected Attributes
bool	_remote
	Does this plugin exist on another resource? More...

VFS_node *	_remoteNode
	The node responding to requests for remote resources. More...

Detailed Description

The interface class for dynamically loaded plugins.

VFS_node_interface is a pure virtual class used to bundle nodes for plugin distribution.

Plugins are loaded from the plugin folders provided on the command line. All identified plugins are loaded immediately, and their initialize() method is called.

Definition at line 9 of file VFS_node_interface.h.

Constructor & Destructor Documentation

◆ VFS_node_interface()

VFS_node_interface::VFS_node_interface ( VFS_node * remoteNode = nullptr )

explicitprotected

VFS_node_interface::VFS_node_interface.

Parameters

remoteNode If this is a remote reference, this is a pointer to the node that will resolve a code request.

Definition at line 88 of file VFS_node_interface.cpp.

◆ ~VFS_node_interface()

VFS_node_interface::~VFS_node_interface ( )

virtual

Definition at line 94 of file VFS_node_interface.cpp.

Member Function Documentation

◆ arguments()

QString VFS_node_interface::arguments ( QString type )

virtual

Describe the arguments needed to create a node.

Parameters

type	The node name

Returns: The argument string.

The implementation of this pure method will look something like:

QString skeletonPlugin::arguments(QString type)
{
   if (type == "skeleton")
           return argumentString( skeleton::staticMetaObject );
 
   return VFS_node_interface::arguments(type);
}

See also: The Skeleton Plugin

Reimplemented in adminPlugin, google_oauth2Plugin, VFS_mongoPlugin, pamPlugin, and VFS_stdlib.

Definition at line 146 of file VFS_node_interface.cpp.

◆ argumentString()

QString VFS_node_interface::argumentString ( QMetaObject s )

protected

Format a constructor string based on a node's metadata object.

Parameters

s	A node's metadata object

Returns: A string representing each of a node's constructors

A node must flag its constructor(s) using Q_INVOKABLE for the signature data to be available.

Definition at line 297 of file VFS_node_interface.cpp.

◆ code()

QString VFS_node_interface::code	(	QString	nodename,
		QString	libname,
		QString &	error
	)

virtual

Request code or other resource from a plugin bundle.

Parameters

nodename	The node providing the code
libname	The library requested
error	A reference to an error string, for writing errors back to the caller

Returns: The raw source code or resource requested

This will generally result in javascript code for a user interface, but could return anything, including base64-encoded images, css, xml, json, etc.

When code is requested, the request is routed to a plugin by nodename. A plugin can service the request itself, or pass it on to a node's static code function. Larger plugins with many nodes will probably want to bundle all their resources together.

It is highly reccommended that if a library is not found, it will call VFS_node::code() for error handling.

See also: VFS_creator::code

Reimplemented in adminPlugin, VFS_mongoPlugin, and VFS_stdlib.

Definition at line 283 of file VFS_node_interface.cpp.

◆ create()

VFS_node * VFS_node_interface::create	(	QString	type,
		QVariantMap	env,
		QDomElement	child
	)

virtual

Create a new node instance.

Base implementation that does nothing.

Returns: The new VFS_node, or 0 (null) if it was unable to create it.

Plugins bundle groups of node definitions together. This is the factory function for creating new nodes.

For example:

VFS_node *myFancyPlugin::create(QString type, QVariantMap env, QDomElement child)
{
    if (type == "myFancyNode")
    {
        int a = VFS_creator::configAttribute(env,child,"alpha").toInt();
        QString b = VFS_creator::configAttribute(env,child,"beta",false,"beta string");
 
        return new myFancyNode(a,b);
    }
 
    if (type == "myMagicNode")
    {
        QString magicPath = VFS_creator::configPathAttribute(env,child,"magicPath");
 
        return new myMagicNode(magicPath);
    }
 
    return 0;
}

Please note the entries for a config file:

As a pure virtual function, this must be implemented in all plugins.

See also: The Skeleton Plugin

Parameters

type	The node type, as listed in provides() and referenced in a config.xml
env	The constructor environment
child	The config DOM element

Returns: Always returns a nullptr

Subclasses must implement this for a plugin to be useful. This base implementation is present so that a minimal plugin can implement initialize() without providing any nodes.

Reimplemented in adminPlugin, google_oauth2Plugin, VFS_mongoPlugin, pamPlugin, VFS_stdlib, and VFS_tcp_mount_directory.

Definition at line 255 of file VFS_node_interface.cpp.

◆ describe()

QString VFS_node_interface::describe ( )

Describe all the nodes in a plugin.

Returns: A description string for each node in provides()

Definition at line 194 of file VFS_node_interface.cpp.

◆ description()

QString VFS_node_interface::description ( QString type )

virtual

Descriptive text about an individual node.

Parameters

type	The node name

Returns: The description string.

The implementation of this pure method will look something like:

QString skeletonPlugin::description(QString type)
{
   if (type == "skeleton")
           return "A node provided as an example for the documentation.  It does nothing.";
 
   return VFS_node_interface::description(type);
}

See also: The Skeleton Plugin

Reimplemented in adminPlugin, google_oauth2Plugin, VFS_mongoPlugin, pamPlugin, and VFS_stdlib.

Definition at line 120 of file VFS_node_interface.cpp.

◆ initialize()

bool VFS_node_interface::initialize ( )

virtual

The plugin initializer.

Returns: bool The initialization status.

This is an opportunity to register filetypes, log data, or perform any other prep work needed.

For instance:

bool myFancyPlugin::initialize()
{
    if (!VFS_node_type::registerType("magic","myFancyPlugin:magicNode",true))
    {    VFS::WARN( "Could not register type 'magic'... is it already registered by something else?" );
         return false;
    }
 
    if (!connectToLicenseServer("myFancyPlugin"))
    {    VFS::WARN( "Could not connect to license server for 'myFancyPlugin'.  License was denied." );
         return false;
    }
 
    return true;
}

If a plugin fails to initialize, it can return false here and will not be added to the plugin registry.

This may also be used to create a (network or other) license check for this node group so future licensed() requests don't have to do network validation. In practice nodes should be licensed per use, not globally when the application starts, and should be checked at some interval for validity.

Reimplemented in adminPlugin, google_oauth2Plugin, pamPlugin, and VFS_stdlib.

Definition at line 184 of file VFS_node_interface.cpp.

◆ isRemote()

bool VFS_node_interface::isRemote ( )

If a plugin represents a remote resource, this value will be true.

Returns: the value of _remote

Definition at line 342 of file VFS_node_interface.cpp.

◆ licensed()

bool VFS_node_interface::licensed ( QString type )

virtual

A licensing mechanism for node creation.

Parameters

type	The node type being queried

Returns: boolean licensing state

By default, all nodes are licensed for use. A plugin can choose to license on a group level or individual node level. It can use network functions or read the filesystem or whatever it needs to do to determine state.

Reimplemented in VFS_stdlib.

Definition at line 224 of file VFS_node_interface.cpp.

◆ provides()

QStringList VFS_node_interface::provides ( )

virtual

A string list of node names that this plugin is prepared to create.

Base implementation that returns an empty list.

Returns: The list of nodes

Plugins bundle groups of node definitions together. This is the list of nodes.

For example:

QStringList myFancyPlugin::provides()
{
    QStringList p;
 
    p << "myFancyNode";
    p << "myMagicNode";
 
    return p;
}

As a pure virtual function, this must be implemented in all plugins.

See also: The Skeleton Plugin

Returns: An empty list

Subclasses must implement this for a plugin to be useful. This base implementation is present so that a minimal plugin can implement initialize() without providing any nodes.

Reimplemented in adminPlugin, google_oauth2Plugin, VFS_mongoPlugin, pamPlugin, VFS_stdlib, and VFS_tcp_mount_directory.

Definition at line 239 of file VFS_node_interface.cpp.

◆ remoteNode()

VFS_node * VFS_node_interface::remoteNode ( )

Return the node needed to satisfy a remote request.

Returns: VFS_node_interface::_remoteNode

By default, this is a nullptr.

Definition at line 354 of file VFS_node_interface.cpp.

Member Data Documentation

◆ _remote

bool VFS_node_interface::_remote

protected

Does this plugin exist on another resource?

Definition at line 50 of file VFS_node_interface.h.

◆ _remoteNode

VFS_node* VFS_node_interface::_remoteNode

protected

The node responding to requests for remote resources.

Definition at line 51 of file VFS_node_interface.h.

The documentation for this class was generated from the following files:

Public Member Functions

Protected Member Functions

Protected Attributes

Detailed Description

Constructor & Destructor Documentation

◆ VFS_node_interface()

◆ ~VFS_node_interface()

Member Function Documentation

◆ arguments()

◆ argumentString()

◆ code()

◆ create()

◆ describe()

◆ description()

◆ initialize()

◆ isRemote()

◆ licensed()

◆ provides()

◆ remoteNode()

Member Data Documentation

◆ _remote

◆ _remoteNode