Library Browser

The Library Browser enables users to browse and search collections of resources such as videos, Tracker tab files (.trk) and Tracker project files (.trz). Collections may be located on a local drive or remote server.

When a resource of interest is found, it can be opened in Tracker with a double-click or downloaded to the local machine with the download button..

1. Opening a collection or resource file

Opening a collection displays it in a tab with a tree in the left pane and an HTML page in the right pane as shown above. The title of the tab is the name of the collection.

Opening a resource file such as a video or Tracker project adds it to the Recent Local Files collection and displays that collection in a tab.

There are three ways to open a collection or resource file into the Library Browser (shown above):

1. Choose a collection by name from the Collections menu or File|Open Recent menu.
2. Choose the File|Open... menu item and use the file chooser to open a file or collection on a local drive. Collections may be either:
1. Directories containing resource files. The resources in the directory are displayed in the tree.
2. XML documents previously saved by the library browser.
3. Enter a path directly into the toolbar URL field as with a web browser.

2. Resource properties

Each resource is represented by a node in a collection tree. Nodes may also be subcollections. Every resource has the following properties:

1. Name: identifies the resource. Displayed as the node name in the tree.
2. Type: may be Collection, Tracker project, EJS model, Video, Image, HTML page, PDF document, or Other. Displayed as the node icon in the tree.
3. HTML page: describes the resource and provides links to additional information. Displayed in the right pane when the node is selected. If no HTML page is defined, the right pane displays the node name, type and (for videos) thumbnail image.
4. Metadata: searchable author names, contact information and keywords. Displayed in the tooltip when the mouse hovers over the node.
5. Target: the resource file itself. Displayed in the URL field on the toolbar when the node is selected. Opened in Tracker (and/or HTML browser or PDF viewer) when the node is double-clicked or the toolbar Open button is clicked. Some nodes (e.g. collection nodes) have no target.

A Tracker project file is a resource that consists of a zip file containing an entire Tracker project, including one or more Tracker tabs with associated videos, HTML/PDF documentation and metadata. For more information see Tracker Projects.

3. The OSP cache

In order to increase performance and provide a searchable database, some files are stored in the Open Source Physics (OSP) cache on the local machine when collections are opened in the library browser.

1. Searchable XML documents that describe the collections and contain references to the actual resource files.
2. HTML pages (and associated images) extracted from zip files.
3. Thumbnail images of videos and ComPADRE Digital Library resources.
4. Resource files that are downloaded from the web when loading into Tracker.

Choose the Manage|Cache... menu item to view the status of the OSP cache in the Library Manager. Click a Clear button to clear cached HTML pages, thumbnails and OSP resources from a particular server. Click the Clear All button to clear the entire cache. Note: searchable cached XML documents are managed separately, and are NOT deleted when clearing the cache.

Reopening a web-based collection that has been previously cached does NOT reload the collection from the web but instead opens the cached XML file. This speeds up the process considerably. To delete the cached XML file and reload the web collection from its source, select the root node and click the Refresh button on the toolbar. Local collections are always opened directly, not from the cache.

4. Searching for resources

To search for resources enter a search term or phrase into the toolbar Search field. Search terms are compared with resource names, resource types, author names, contact information, keywords and other metadata defined by a resource. Search terms are case-insensitive but must be matched in their entirety. Note: only resources defined in searchable cached XML documents can be discovered. For this reason, it is recommended that you open all collections of interest when first using the library browser (be sure to leave them open long enough to fully load and save themselves in the cache--for some collections this can take several minutes).

Search results are displayed in a new tab.

The tree nodes displayed in the search results are fully functional--that is, you can browse or open them in Tracker in the usual way. But it is often useful to open them in their original collections which may contain related resources. To open a search result in its original collection, right-click the node and choose Show Original from the popup menu.

To fine-tune your search you can use the logic operators AND and OR (must be upper case) in your search phrase. When using more than one logic operator you should include parentheses for clarification (e.g. "yo-yo OR (disk AND energy)"). The search terms separated by these operators are used independently as described above, then the independent results are combined logically to obtain the final search results.

Click the Search Targets button to choose which cached XML documents to search. You can delete an unwanted XML file from the search cache by clicking its Delete button in the Search Targets tab of the Library Manager.

5. Managing collections

The library browser provides direct access to collections in the following digital libraries, available in the Collections menu:

1. A local library called My Library, managed by the user and discussed in this section.
2. The ComPADRE Digital Library, a part of the National Science Digital Library system.
3. The Tracker Home Library, managed by the Open Source Physics project.
4. The Shared Library containing collections contributed by other educators and students. To find out how to share your own collections, see Building the shared and ComPADRE libraries.

My Library initially contains the Recent Local Files collection, which shows all recently opened resources, and the editable My Collection collection to which the user can add resources as described in Editing local collections below. It is easy to customize My Library by adding your own favorite collections.

There are two ways to add a collection to My Library:

1. Open the collection of interest in a tab, then right-click the tab and choose Add this to My Library from the popup menu. You will be prompted to assign the collection a name for the Collections menu.
2. Choose the Manage|My Library... menu item to open the Library Manager, then click the Add button and enter the collection URL in the Add Collection dialog. You will be prompted to assign the collection a name for the Collections menu.

The Library Manager also enables you to rename, reorder and/or remove collections from My Library. To rename a collection, select it and edit the name in the Name field. To reorder or remove a collection, select it and use the buttons provided. Note: renaming a collection changes only its menu name, not its tab title.

6. Creating and sharing resources and collections

Resources: resources may be one of the following:

1. Tracker tab or project: TRK or TRZ file. Opened in Tracker.
2. Video or image: video or image file. Opened in Tracker.
3. HTML pages: HTML file. Opened in the default HTML browser.
4. PDF documents: PDF file. Opened in the default PDF viewer.

Collections: there are two types of collections, live and XML. Live collections are views of resource files in a single directory (with subdirectories if desired). XML collections are XML documents with references to resource files which can be anywhere, including other servers.

1. Live collections: This is the easiest option.
1. Local: put the resources into a local directory and open the directory in the library browser. Optional but recommended: add HTML information files to the same directory (see below).
2. Web: put the resources along with the OSP Digital Library PHP script into a directory on a server (see Sharing Your Tracker Collection) and open the URL path to the script in the library browser. Optional but recommended: add an HTML information file to the server directory (see below). Note: the server must run the PHP script. You may have to change the script extension. Check with your web administrator if unsure.
2. XML collections: This is the most flexible option.
1. Use File|New Collection... to create a new empty XML collection or File|Save Collection As... to create an XML copy of an open collection.
2. Edit the XML collection as described in Editing XML collections.
3. To share the XML collection on the web, see Uploading XML collections to the web.
4. Open the URL path to the XML file in the library browser.

7. HTML information files for live collections

Resources in live collections (with the notable exception of Tracker projects) will have minimal documentation and metadata unless you add correctly named and coded HTML information files to the same directory. For effective HTML information files, use the following guidelines:

1. Filename: strip the extension and append "_info.html" to the name of the PHP script or resource target file (e.g. "library_collection_info.html" for script "library_collection.php", "wheels_info.html" for local directory "wheels", "loop2_info.html" for tracker file "loop2.trk" or video file "loop2.flv").
2. Title: set the <title> in the HTML <head> section to the desired resource or collection name (e.g. <title>Modeling a Hot Wheels Loop</title>).
3. Metadata: add a <meta> tag in the HTML <head> section for each type of metadata you wish to include. For example:

<meta name="author" content="Douglas Brown">
<meta name="contact" content="Cabrillo College">
<meta name="keywords" content="circular motion, centripetal acceleration, toy truck, Newton's second law">

4. Body: include a brief description of the collection or resource, including image and hyperlinks if desired. Remember that the HTML pane in the library browser may be small. Extensive documentation and/or instructions should be in separate HTML and/or PDF resources.

8. Editing XML collections

An XML collection saved on a local drive is editable by default unless it has been set to read-only by the operating system. To edit a local collection, open it in the library browser and click the Open Editor button on the toolbar. The editor displays (a) a button bar for creating and organizing resource nodes and (b) data fields for describing and defining the resources themselves.

Button bar: the button bar provides the following buttons:

• Add Resource and Add Collection (available only when a collection node is selected): click to add a new resource or subcollection node to the selected node.
• Copy Node and Cut Node: click to copy or cut the selected node to the clipboard. Note: the only way to delete a node is to cut it.
• Paste Node (available only when a collection node is selected): click to add the clipboard node to the selected node.
• Move Up and Move Down: click to change the position of the selected node.
• Show Metadata: click to show the metadata fields.

These button actions can also be executed by right-clicking a node and selecting the action from the popup menu. Note: the Copy Node action is available by right-clicking any node in any collection, even when not editing. This enables users to easily add any resource to their own collection.

Data fields: the data fields display the following resource properties:

• Name: the node name displayed in the tree.
• Type: the type of resource. May be Collection, Tracker Project, EJS Model, Video, Image, HTML Page, PDF Document, or Other.
• HTML File (optional): the path to the file displayed in the HTML pane when the node is selected. The path may be absolute or relative to the base URL (see discussion below).
• Base URL (optional): the base URL used to resolve relative paths for the HTML and resource files.
• Resource (disabled for collection nodes): the path to the resource target file. The path may be absolute or relative to the base URL (see discussion below).

Metadata fields: clicking the Show Metadata button displays the following additional fields (not shown in the figure above):

• Author: the authors of the project.
• Contact: contact information for the authors (e.g. institution, email, etc.).
• Keywords: searchable keywords and phrases. It is common, but not required, to separate key phrases with commas.
• Metadata (dropdown list of metadata names and values): additional metadata names and values of any kind can be entered here.

To view the metadata defined for a resource without showing the metadata fields, hover over the node with the mouse to display the tooltip.

9. Absolute and relative paths in XML collections

In the collection editor, resource and HTML paths may be entered as absolute or relative to the base URL. In general, relative paths are preferable for the following reasons:

• The base URL can be defined for an entire collection or subcollection. Child resources inherit the parent base URL automatically, making it unnecessary to re-enter a path repeatedly. When a resource inherits from its parent the path is displayed in a pale green color as shown in the figure above. To override the parent, simply enter a new path in the Base URL field.
• It is faster, easier and more accurate to enter and read short (relative) resource and HTML file names.
• If the actual resource and HTML files are stored in a directory structure that can be moved and/or uploaded as a unit, then the entire collection file can be updated by changing only the base URL(s).

To convert an absolute path to relative (or vice-versa), right-click the Resource or HTML File field and choose Set to relative (or Set to absolute) from the popup menu.

10. Uploading XML collections to the web

XML collections can only be created, edited and saved on a local drive. But by uploading your resources to the web and changing the base URL of your collection, your XML collection becomes completely portable--you may email the XML file to others, post it on the web or share it on a local network. For example. the Rolling and Slipping collection shown being edited above can now be found at https://physlets.org/tracker/library/roll_slip_collection.xml.

To put your local collection on the web, open the XML file in the library browser and follow these steps (this assumes you have assembled your resource target and HTML files locally and used relative paths in the collection editor as described above):

1. Identify the server directory you will use for your web collection (e.g. "www.my_institution.edu/my_shared_projects").
2. Upload your resource files (including subdirectories, if any) to the server directory.
3. Open the collection editor, and select the root node.
4. Change the base URL to the server directory URL path (e.g. "http://www.my_institution.edu/my_shared_projects").
5. If needed, change the base URL of other subcollections or resources in your collection.
6. Browse your collection to verify that the web resources are available and behaving as expected.
7. Save the modified XML collection file (or Save As to preserve the original).

11. Building the Shared and ComPADRE libraries

The Shared Library contains collections contributed by other Tracker users, and we encourage you to help build the library by developing and hosting web-based collections (Tracker projects and/or videos) and emailing the collection path to the Shared Library editor, Douglas Brown (dobrown at cabrillo dot edu). Collections that are added to the library are immediately available from the Collections|Shared Library menu visible to all Tracker users.

The ComPADRE Digital Library, a part of the National Science Digital Library system, is a growing network of educational resource collections supporting teachers and students in Physics and Astronomy. As a user you may explore collections designed to meet your specific needs and help build the network by recommending resources, commenting on resources, and starting or joining discussions. For more information, see <http://www.compadre.org/OSP/>. To recommend an OSP resource for ComPADRE, visit the Suggest a Resource page at <http://www.compadre.org/osp/items/suggest.cfm>. Contact the OSP Collection editor, Wolfgang Christian, for additional information.