webgen is a command line application for generating a web site from templates and content files. Despite this fact, the implementation also provides adequate support for using webgen as a library and full support for extending it.
The Webgen namespace houses all classes/modules used by webgen. The class Webgen::Website is the main class, you might want to have a look at its documentation.
webgen can be extended very easily. Any file called init.rb put into the ext directory of the website or into one of its sub-directories is automatically loaded when a Webgen::Website object is created (by using a Webgen::BundleLoader).
You can extend webgen in several ways. However, no magic or special knowledge is needed since webgen relies on the power of Ruby itself. So, for example, an extension is just a normal Ruby class.
Following are links and descriptions on how to develop specific types of extensions:
- Webgen::Task
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Information on how to implement functionality that operates on a website in a standard manner.
- Webgen::Source
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Information on how to implement a class that provides source paths for webgen. For example, one could implement a source class that uses a database as backend.
- Webgen::Destination
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Information on how to implement a class that writes content to a destination location. The default destination class just writes to the file system. One could, for example, implement a destination class that writes the generated files to multiple locations or to a remote server.
- Webgen::ContentProcessor
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Information on how to develop an extension that processes the content. For example, markup-to-HTML converters are implemented as content processors in webgen.
- Webgen::PathHandler
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Information on how to implement a class that handles objects of type Path and creates Node instances. For example, Webgen::PathHandler::Page handles the conversion of ‘*.page’ files to ‘*.html’ files.
- Webgen::Tag
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Information on how to implement a webgen tag. webgen tags are used to provide an easy way for users to include dynamic content such as automatically generated menus.
- Webgen::ItemTracker
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Information on how to implement a class that tracks certain items that can be used to determine wheter a given node object has changed.
Here is a list of modules/classes that are used throughout webgen and provide useful methods for developing extensions:
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Webgen::Path (represens a source path that will get converted into a Webgen::Node)
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Webgen::Node (the internal representation of destination paths)
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Webgen::Tree (the tree structure holding all Webgen::Node objects)
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Webgen::Page (provides methods for working with files in Webgen Page Format)
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Webgen::Cache (provides caching functionality for other objects)
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Webgen::Utils (a collection of useful utilities)
The blackboard (a Webgen::Blackboard object, accessible via Webgen::Website#blackboard) provides an easy-to-use facility to be notified of certain messages. All registered listeners for a message are notified when the message gets dispatched.
Following is the list of all messages that are dispatched by the webgen core classes and built-in extensions:
- :website_initialized
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This message is dispatched once a Webgen::Website object is fully initialized, ie. after all extensions have been loaded, the configuration applied and frozen and the cache restored (which is also immediately before Webgen::Website.new returns).
No parameters are given.
- :apply_meta_info_to_path
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This message is dispatched before a node from a path is created and can be used to add additional meta information to the path.
The path in question is given as parameter.
- :before_node_created
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This message is dispatched after the meta information from the configuration option ‘path_handler.default_meta_info’ is applied to a path but before anything else happens to the path (like updating the meta information has with meta information found in the content of the path).
The path in question is given as parameter.
- :reused_existing_node
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This message is dispatched when a node that should be created already exists and is therefore not created again (which would lead to an error). An example would be fragment nodes that are created during the rendering.
The node is given as parameter.
- :after_node_created
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This message is dispatched after a node has been created.
The node is given as parameter.
- :before_secondary_nodes_created
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This message is dispatched before secondary nodes are created from a Webgen::Path object.
The path in question and the node alcn which led to the creation of the path (may be
nilif the secondary nodes are not created during rendering) are given as parameters. - :after_secondary_nodes_created
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This message is dispatched after secondary nodes have been created from a Webgen::Path object.
The path in question and the created nodes are given as parameters.
- :after_tree_populated
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This message is dispatched after all initial nodes have been created and the tree has been populated. Note that further :after_node_created messages may be dispatched because nodes can additionally be created during the rendering phase.
No parameters are given.
- :before_all_nodes_written
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This message is dispatched before any node is written to its destination in a generation pass. Since webgen may need multiple passes to correctly write all nodes, this message may also be dispatched multiple times.
No parameters are given.
- :before_node_written
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This message is dispatched after webgen determined that the content of a node has changed but before it is written to its destination. Note that this message is also dispatched for those nodes whose ‘no_output’ meta information key is set to
true.Also note that this message be may dispatched multiple times for the same node if, after all nodes have been written, it is determined that it has changed again.
The node in question is given as parameter.
- :after_node_written
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This message is dispatched after a node has been written to its destination. Note that if the node in question has the meta information ‘no_output’ set but the Webgen::ItemTracker has determined that it has changed nonetheless, this message is still dispatched because the node would have been written.
Also note that this message be may dispatched multiple times for the same node if, after all nodes have been written, it is determined that it has changed again.
The node and its (possibly) rendered content are given as parameters.
- :after_all_nodes_written
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This message is dispatched after all nodes have been written. Note that this message is dispatched multiple times if needed (if nodes have changed again).
No parameters are given.
- :node_resolution_failed
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This message is dispatched when webgen tries to resolve a node by using an alcn/acn/absolute path, the node could not be found and it is deemed that this resolution failure is critical.
The path in question as well as the requested language are given as parameter.
- :before_node_deleted
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This message is dispatched before a node is deleted from the Webgen::Tree. When this message is dispatched, all child nodes have already been deleted.
The node is given as parameter.
- :website_generated
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This message is dispatched after the website is completely generated.
No parameters are given.