Browsing - Overview and Contents

Through a combination of database tables and collmgr field configuration, dynamic browsing is available through the DLXS middleware. When the proper CGI-based URL is received, the middleware checks for certain metadata in the database tables, packages some of it in XML, uses some of it, as is in its stored format of XML, and lets XSLT format the results. At run time, no XPAT queries are needed, only MySQL queries are run against the item browse tables in the dlxs database.

After the tables are prepared, that is, populated with item metadata through the $DLXSROOT/bin/browse/updatebrowsedb.pl script (aka "database populator"), configuration for the behavior of dynamic browsing is accomplished by modifying certain collmgr fields.

Provisions will soon be made for creating static HTML browse pages with the database populator script.

Item browse database tables

There are three tables in the dlxs database that are specifically used for dynamic browsing in the middleware:

ItemColl
ItemBrowse
ItemBrowseCounts

The ItemColl table holds, for each item/document and collection combination, one row containing the following columns:

the idno
the collection id
the modification date of the row's information
XML metadata about the item: in the case of TextClass, this is simply the DLXSTEXTCLASS/HEADER element that is retrieved from an XPAT query in the "database populator" script. In the case of ImageClass, the Perl subclass used by the database populator grabs information from the MySQL or XPAT data and wraps it in specific XML before filling in this field.

The ItemBrowse table holds, for each item/document's browseable field (e.g., author, title, etc.):

the idno
the field name
the value of the field
rank (not currently used)

The ItemBrowseCounts table holds, for each collection, a list of rows containing:

colleciton id
the field name
the first character or the first two characters of the sortable field's value (sortable title, author's name)
the count of items that begin with that first character or those first two characters

Collmgr fields for configuration

The main fields in the collmgr that need to be set properly are:

locale
browsenav
browsefields

See Configure the collmgr fields below for more information.

Preparing collections for browsing

Configure the collmgr fields

Start collmgr and change the following fields:

devhost: if you are running the database populator in a development environment (that is, where DLPS_DEV environment variable is set), you can have the middleware use XPAT-indexed data that is on a machine different from the usual host. This can be useful for testing purposes.
locale: (this should be changed to a UTF-8 type of encoding, e.g., en_US.UTF-8)
browsenav: enter 0, 1, or 2. If you want no paging, that is, that all items in the colleciton appear on one HTML page for the user to browse, enter 0. Enter 1, if you want "one level of browsing", that is, that a separate page be created for each first character of the value in question (e.g., title or author) and that a navigation bar be built that allows the user to navigate to each page, for example, jump to the page listing items whose value begins with "M". Entering 2 in this field will create a "two-level browse", where two navigation bars will be created. The first bar will allow the user to jump to items whose values begin with a particular first character (e.g., jump to the records that begin with "B"). The second navigation bar will allow the user to jump to items whose values begin with a particular two-character combination, (e.g., records that begin with "Bu"). This decision is left to the collection coordinator. We have found that the level is based on how many total items there are in the collection and therefore what is a reasonable number of browseable items for a single HTML page.
browsefields: list the browseable fields for the collection. For example, some collections may have only title browsing, others may need both title and author, etc.

Populating the item browse tables

To initially populate or to update the item browse tables, simply run the database populator. To do so, enter:

$DLXSROOT/bin/browse/updatebrowsedb.pl class=AAA c=BBB host=CCC

where AAA is either "text" or "image" and where BBB is the collection id of the collection you want to create browsing for and CCC is the name of the host on which resides the XPAT index for the collection. You may want to point the script at new or test data on a machine that is different from your production machine. If that is the case, you may also want to change the devhost field for the collection in collmgr and test the collection in development mode (with the DLPS_DEV environment variable set).