Data Sources

Contents or URLs can be searched for using the <contents>, <templates> or <media> tags, which allow you to search a data source (directory, delimiter-separated-values file, database etc.) for a pattern.

<contents> and <media> tags can also pick up metadata from metatable files while searching for content or media items, using the metatable attribute.

Currently two data source protocols are defined, file: and svfile: .

Attributes Supported By Datasource Tags

src

All datasources require this attribute, which specifies a protocol and path, in a URL-style syntax: protocol:path . file: is the default protocol, if none is specified.

name

This attribute is used to specify the pattern of data, under this path, which will be converted into content or media items. The part of the data's location which matches this name pattern will become the name of the item. Typically, WebMake glob patterns, such as "*.txt" or ".../*.html" are used.

skip

A pattern which should match filenames that should be skipped. Files that match this pattern will not be included as content or media items, or as metatables. Glob patterns, again, are used here.

prefix

The items' names can be further modified by specifying a prefix and/or suffix; these strings are prepended or appended to the raw name to make the name the content is given.

suffix

See above.

namesubst

a Perl-formatted s// substitution, which is used to convert source filenames to content names. See the example under The File: Protocol, below.

nametr

a Perl tr// translation, which is used to convert source filenames to content names.

listname

a name of a content item. This content item will be created, and will contain the names of all content items picked up by the <contents> or <media> search.

metatable

a search pattern, similar to name above, which provides filenames from which metadata will be loaded.

metatableformat

The format for the above metatable files.

In addition, the attributes supported by the content tag can be specified as attributes to <contents>, including format, up, map, etc.

Also, the attributes supported by the <metatable> tag can be used if you've specified a metatable attribute. Note that metatableformat should be used instead of format, as format is already used for the content items.

The content blocks picked up from a <contents> search can also contain meta-data, such as headlines, visibilty dates, workflow approval statuses, etc. by including metadata.

The file: protocol loads content from a directory; each file is made into one content chunk. The src attribute indicates the source directory, the name attribute indicates the glob pattern that will pick up the content items in question.

<contents src="stories" name="*.txt" />

The filename of the file will be used as the content chunk's name -- unless you use the namesubst command; see below for details on this.

Note that, for efficiency, the files in question are not actually opened until their content chunks are referenced using ${name} or get_content("name").

Normally only the top level of files inside the src directory are added to the content set. However, if the name pattern starts with .../, the directory will be searched recursively:

<contents src="stories" name=".../*.txt" />

The resulting content items will contain the full path from that directory down, i.e. the file stories/dir1/foo/bar.txt exists, the example above would define a content item called ${dir1/foo/bar.txt}.

If you use the namesubst command, the filename will be modified using that substitution, to give the content item's name. So, for example, this contents tag:

<contents src="stories" name="*.txt" namesubst="s/.txt//" />

will load these example files as follows:

Filename	Content Name
stories/index.txt	${index}
stories/foo.txt	${foo}
stories/directory/bar.txt	${directory/bar}
stories/zz/gum/baz.txt	${zz/gum/baz}

You can now load metadata from external files while searching a directory tree for content items or media files. This allows you to load image titles, etc. from files which match the filename pattern you specify in the metatable attribute.

The attributes supported by the <metatable> tag can be used in the datasource tag's attribute set, if you've specified a metatable attribute, allowing you to define the format of the metatable files you expect to find.

There's one major difference between normal metatables and metatables found via a data source; the names in this kind of metatable refer to the content or media object's filename, not its content name.

In other words, the names of any content items referred to in the metatable files will be modified, as follows:

• if the name attribute contains .../, then the content items could be deep in a subdirectory. The metatable file does not have to contain the full path to the content item's name; it can just contain the item's filename relative to the metatable itself.
• if a namesubst or nametr function is specified, the content names in the metatable will be processed with this. Again, this means that the metatable data just has to provide the filename, not whatever the resulting content item will be called.

These features will hopefully make the operation a little more intuitive, as users who add files to a media or contents directory will not have to figure out what the resulting content item will be called; they can just refer to them by their filename, when tagging them with metadata.

The svfile: protocol loads content from a delimiter-separated-file; the src attribute is the name of the file, the name is the glob pattern used to catch the relevant content items. The namefield attribute specifies the field number (counting from 1) which the name pattern is matched against, and the valuefield specifies the number of the field from which the content chunk is read. The delimiter attribute specifies the delimiter used to separate values in the file.

<contents src="svfile:stories.csv" name="*"

namefield=1 valuefield=2 delimiter="," />

New data sources for <contents> and <media> tags are added by writing an implementation of the DataSourceBase.pm module, in the HTML::WebMake::DataSources package space (the lib/HTML/WebMake/DataSources directory of the distribution).

Every data source needs a protocol, an alphanumeric lowercase identifier to use at the start of the src attribute to indicate that a data source is of that type.

Each implementation of this module should implement these methods:

new ($parent)

instantiate the object, as usual.

add ()

add all the items in that data source as content chunks. (See below!)

get_location_url ($location)

get the location (in URL format) of a content chunk loaded by add().

get_location_contents ($location)

get the contents of the location. The location, again, is the string provided by add().

get_location_mod_time ($location)

get the current modification date of a location for dependency checking. The location, again, is in the format of the string provided by add().

Notes:

• If you want add() to read the content immediately, call $self->{parent}->add_text ($name, $text, $self->{src}, $modtime).
• add() can defer opening and reading content chunks straight away. If it calls $self->{parent}->add_location ($name, $location, $lastmod), providing a location string which starts with the data source's protocol identifier, the content will not be loaded until it is needed, at which point get_location_contents() is called.
• This location string should contain all the information needed to access that content chunk later, even if add() was not been called. Consider it as similar to a URL. This is required so that get_location_mod_time() (see below) can work.
• All implementations of add() should call $fixed = $self->{parent}->fixname ($name); to modify the name of each content chunk appropriately, followed by
  $self->{parent}->add_file_to_list ($fixed); to add the content chunk's name to the filelist content item.
• Data sources that support the <media> tag need to implement get_location_url, otherwise an error message will be output.
• Data sources that support the <contents> tag, and defer reading the content until it's required, need to implement get_location_contents, which is used to provide content from a location set using $self->{parent}->add_location().

• Data sources that support the <contents> tag need to implement get_location_mod_time. This is used to support dependency checking, and should return the modification time (in UNIX time_t format) of that location. Note that since this is used to compare the modification time of a content chunk from the previous time webmake was run, and the current modification time, this is called before the real data source is opened.