The previous chapter presents introductory material.

Viewer Software

The viewer software provides the user interface for accessing information in the electronic publishing system. Since electronic publishing provides the user with access to a vast amounts of published information, the most appropriate metaphor appears to be that of a library. While at first thought the library metaphor might seem to be quite simple, anyone who has recently walked into a reasonable sized library knows what a daunting experience libraries can be, particularly for someone who is an infrequent library visitor. This section focuses in on the issues of providing a reasonable user interface to electronic publishing.

The Library Metaphor

The central task of using a library is the one of letting the user relatively easily navigate themselves to the information they are interested in. In current libraries, the basic information navigation tool is the "card" catalog which indexes the library's books based on author, subject, and title. Since many libraries have already discovered that it is economical to replace their paper based card catalogs with electronic ones, it is somewhat humorous to note that card catalogs no longer seem to have any cards. To eliminate this possible confusion, this paper refers to the card catalog as the author/subject/title indices. As a general rule, each library book typically has one entry in each of the author, subject, and title indices; exceptions to the general rule abound (e.g. multi-author books, multi-subject books, books with no easily identifiable author, etc.) While author/subject/title indices have limitations, all viewer software presenting a library metaphor for electronic publishing will provide access to these basic indices.

In addition to the standard author/subject/title indices, many libraries also purchase or maintain other indices. Examples of other indices are:

Periodical Index: A list of all periodicals maintained by the library.
Books in print: A list of books that are still available from publishers.
Forthcoming books: A list of books scheduled to be printed in the near future by publishers.

The viewer software must provide reasonable means for finding and using these additional indices.

Of course, whenever the user is having difficulty locating some information, a librarian can be consulted. A librarian is frequently able to help a user locate the information they are interested in (then again, sometimes a librarian does not have a clue.) Since the viewer software is presenting electronic publishing as a vast electronic library, it seems natural that users will occasionally need to consult with real, live, flesh-and-blood librarians. The consultation can be done either via electronic mail or by simply picking up the phone and calling a librarian directly. Since librarians must earn a living, there must be a way for compensating librarians for their services. The librarian compensation issue is discussed further below.

Accessing electronically published information is not free. In general, there is a tension between the authors who wish to maximize the amount of royalties collected and the users who are equally interested in reducing the amount of royalties they pay out. Free market economics will dictate what royalties authors and users find mutually acceptable. The viewer software needs to provide the user with the ability to set a royalty pay out level below which they will not be bothered; whenever an author asks for royalties that exceed this pay out level, the user is queried to see whether they are willing to pay the higher royalty rate.

The User Interface

Before discussing the viewer software issues in greater detail, it is worthwhile to go through some example viewer software screens. By the time electronic publishing is deployed, computers with window systems will be the norm (e.g. Microsoft Windows, Macintosh System 7, Unix Motif, etc.) Generally, window systems provide the user with multiple overlapping windows that can be independently resized and rearranged. In addition, the user has the ability to point at a screen location with a pointing device (i.e. a mouse) and click some sort of button (i.e. a mouse button) to cause an action to occur. The screens shown below do not adhere to any particular graphical look-and-feel, since look-and-feel standards vary depending upon window system being used. Hence, the box surrounding a line with two arrowheads corresponds to a stylized scroll bar that is meant to be adapted to the window system's standard look-and-feel as appropriate. In the screen examples shown below, clicking on a small shadow box causes the viewer software to perform some action; usually, the desired action is pretty obvious from the box location.

The design of good graphical user interfaces is extremely difficult and should be designed in conjunction with at least one human factors specialist. Since the screens shown below were not done in conjunction with a human factors specialist, they should merely be viewed as a broad outline of what viewer software should look like. In particular, the decision to always reuse the same window for displaying information is really quite arbitrary and should be revisited as a design decision.

After the user has installed the viewer software, they will be presented with window that looks somewhat like the one shown below. The top window panes stay pretty much the same as the user navigates through the electronic library. The lower half of the window contains the current view into the library. It starts out at the "top level" which is basically the standard author/subject/title indices and a customized menu list. The example shown below has a fairly simple customized top level menu consisting of Mail, Newspapers, Magazines, References, Catalogs, and Weather. Clicking on the box labeled "Top" always brings the user back to this top level window; similarly, clicking on "Back" takes the user back to the previous view. Clicking on "Properties" brings up a property sheet that permits the user to customize the viewer software; in particular, it is from the property sheet that the user can create and rearrange the customized menus accessible from the top level window. The properties window is discussed further below.

Properties Window

When the user clicks on the box labeled "Author Index" in the top level window, an search window that looks somewhat like the one shown in the search window below is presented; in this example, the user has searched for an author named "Heinlein" and found the fairly well known science fiction author named Robert A. Heinlein. The subject and title index windows look very similar to the author index window. The user can click on one of the book glyphs to immediately jump to the selected book.

For the example shown above, if the user clicks the book glyph for "Beyond This Horizon", a book view similar to the one below is shown. A book typically starts out with the title, author and copyright information followed by a table of contents. By clicking on one of the chapter glyphs in the table of contents, the user is immediately taken to the specified chapter and reading can commence; alternatively, the user can just use the scroll bar to scroll past the end of the table of contents to find chapter 1.

Book Window

The first thing to notice about the example user interface is that it models a library very closely. A user can walk into just about any library in the world, find the card catalog (or its equivalent) and start searching for information. The library metaphor is followed closely, except that rather than getting an index number and searching for the book in the stacks, the user can start reading the information immediately.

Hypertext Links

One of the exciting facilities that electronic publishing can provide over and above what is available with paper publishing is the ability to interconnect material via hypertext links. The term "hypertext link" was originally coined by Theodore (Ted) Nelson and corresponds to a facility whereby a user can quickly jump from one piece of material to another piece of (usually) related material.

For electronic publishing it is useful to distinguish between two kinds of hypertext links - embedded and overlaid. An embedded hypertext link is one that is published with a document and is always displayed. An overlaid hypertext link is one that is published separately from the original document; the viewer software will provide the user with the ability to control which overlay hypertext links are to be displayed in conjunction with a document.

Embedded hypertext links can be further categorized into intra-document and inter-document hypertext links. Intra-document hypertext links are ones that jump around within a document; some examples of intra-document hypertext links are:

to connect a table of contents to the corresponding chapters
to interconnect a document index back to the corresponding document sections.
to provide for footnotes.
to provide for internal cross references within a document.
to connect a piece of text to an embedded figure or table.

Inter-document hypertext links are ones used to reference other separately published documents that quite possibly reside in other repositories; examples of inter-document hypertext links are:

the ability directly access information that is found in a bibliography.
the ability to connect an author/subject/title index entry to a document.
the ability to quote material directly out of another document by reference without having to copy the quote. This kind of quote is quite appealing in that both saves space and permits royalties to be shared amongst multiple authors.

To the user, embedded hypertext links would manifest themselves as some sort of glyph which if clicked upon, would cause the hypertext link to be traversed. After the user has examined as much of the information at the other end of the hypertext link, clicking on the box labeled "Back" will return the user to where they came from.

Overlay hypertext links are published separately from the documents that they are attached to. The authors of overlay hypertext links collect royalties whenever the user decides to traverse one of them. Thus, in electronic publishing there is money to be made in both publishing original documents and publishing overlay hypertext links that interconnect the documents.

The naive view of overlay hypertext links is that they are global and all of them will always be displayed. Alas, the quality of overlay hypertext links will vary greatly and users will quickly tire of experimenting to find out which ones are interesting or not, particularly if the user is paying for the privilege of traversing the links. A more realistic model of overlay hypertext links is that there will be a number of organizations that publish groupings of overlay hypertext links and users will pick a number of these overlay groupings to display. Organizations that maintain high quality standards for their overlay hypertext link groupings will be actively subscribed to; conversely, organizations with lower quality standards will be less actively utilized.

The most common form of overlay hypertext link will be a unidirectional point-to-point link. As the user is reading a document, occasionally they will come across a glyph that marks one end of a unidirectional point-to-point link. In the examples below, an end-point will be represented as a circle with a number in it. When the user clicks on an end-point glyph, a hypertext link summary window similar to the one below is popped-up and it is scrolled to show the appropriate end-point glyph. By convention, unidirectional point-to-point hypertext links are structured so that the bulk of the cost of traversing the link does not occur until the user clicks on the appropriate box in the overlay hypertext links window. Bidirectional point-to-point links are constructed using two unidirectional point-to-point links.

Hypertext Link Window

The Property Sheet

The user controls the viewer software behavior through the property sheet window. The user brings up the property sheet by clicking on the box labeled "Properties". The property sheet is used to:

create/delete/maintain accounts and set royalty thresholds
customize top-level menus
control the rendering of text
select overlay hypertext groupings
select filtering options
mask/highlight spans of text

Account Property Sheet

Before a user can use the viewer software at all, at least one account must be set up. Since multiple people might use same machine and viewer software, the viewer software must implement the concept of an account (e.g. members of the same family.) An account registration portion of the property sheet might look somewhat as shown below:

Account Window

An account contains:

an account name, password, and privilege. Each account is named, typically with the first name of the person who will use it. Since usage of electronic publishing results in usage/royalty payments, it is prudent to protect account usage with a password. A privileged account is one that can create, delete, and change other accounts. Accounts set up for children will almost certainly have restrictions placed upon them.
an electronic bank phone number and account number. Each account may choose to utilize a different electronic bank. An electronic bank is identified by the phone number to call to interact with it.
a cache phone number. Each account may choose to utilize a different cache service. Like electronic banks, a cache is identified by the phone number to call to interact with it.
royalty/usage thresholds. While "a picture is worth a thousand words" it may take substantially more storage than 1000 words. Thus, users will choose to pay differing rates for text, images, audio, and hypertext links. The user can set a payment threshold for each of these information types. Whenever the user attempts to access information that exceeds one of these thresholds, a pop-up window will appear that queries the user whether or not the higher rate is acceptable.
account thresholds and transfer amounts. The user specifies a cache account threshold below which additional money is transferred from the user's electronic bank account to the cache account; the amount transferred is also user specified. Whenever the electronic bank account balance drops below the electronic bank account balance threshold, the user is informed via a pop-up that the electronic bank account needs to be replenished.

The Masks Property Sheet

The masks portion of the property sheet allows the user to control information masking. Information masks allow adults to restrict and/or emphasize information. The primary purpose of the masking facility is to provide a mechanism for parents to impose some quality standards and/or restrictions on the electronically published material that their children access. A masking facility is required since electronic publishing will not be able to enforce any standards on any of the electronically published material. While restricting information from adults is a dubious practice, restricting information from children is quite common. If the viewer software lacks a masking facility, many parents will choose to entirely disallow their children from independently accessing any electronically published material; this would certainly be unfortunate.

The "Masks Property Sheet Window" shown below is obtained by clicking on the box labeled "Masks" in the property sheet window. The first step towards selecting a mask is to find it. By clicking on the box labeled "Search" a search window very similar to the author search window is shown in the main window; this window is called the "Mask Search Window". The user can search and scroll through the mask search window for whatever masks seem appropriately interesting. Organizations will choose to publish mask sets either for profit or for because they feel strongly about their particular mask criteria; those organizations in the latter category will probably price their mask as close to free as they can. Whenever an appropriate mask is found, the user first clicks on the box labeled "Add" and then clicks on the box next to the desired mask to cause the named mask to show up in "Mask List". Masks can be deleted from "Mask List" by first selecting the mask to be deleted and then clicking on the box labeled "Delete". (The placement of the "Search", "Add", and "Delete" controls seems sub-optimal, to say the least.)

Mask Windaow

A mask's display characteristics are shown by selecting the desired mask in "Mask List". They can be modified by simply going through the display characteristics and changing them. A mask that is locked can only be changed by a privileged account. Parents that are setting up accounts for children will almost certainly choose to lock some of the masks. A mask for which "Exclusively" has been selected, will suppress all material that does not meet the specified mask. In general, it is best to only have one mask at a time set to "Exclusively". Conversely, a mask for which "Elide" has been selected will replace all material that meets the criteria with an ellipses (i.e. "...") The other font characteristics can be set to provide additional highlighting.

The implementation of masks is very similar to hypertext links and is deferred until repositories are discussed.

The Filter Property Sheet

If the world library is to live up to its name, it will contain vast amounts of material is either out-of-date and/or written in an unfamiliar language. If all of the out-of-date and/or unfamiliar language material index entries are presented intermixed with up-to-date and familiar language material in a single index, the task of culling out the uninteresting entries is foisted upon the user, thereby making the index very difficult to use. The problem of culling out uninteresting index entries is called the index clutter problem and if it is not solved, indices will be extremely difficult to use. The solution to the index clutter problem is to provide filtering facilities that allow the user to suppress the display of index entries that are unlikely to be of interest. While filtering can be based on the more generic masking facility, for both performance and cost reasons, it is more appropriate to special case the filtering based on publication date and language.

When the user clicks on the box labeled "Filter" a filter property sheet similar to the one below is shown. The user can activate the dates that they are interested in clicking on the box next to the date ranges they are interested. The selection of a set of languages is very similar to mask selection. Clicking on the box labeled "Search" causes the main window to display a language search window very similar to the author search window. When the user wishes to add a language to "Language List", the box labeled "Add" is clicked followed by clicking the language box in the language search window. A language is removed from the "Language List" by clicking on the box labeled "Delete" followed by clicking on the appropriate language box in the "Language List". Individual language are toggled on and off by clicking on the appropriate language box in the "Language List".

Filter Window

The implementation of filters is deferred until repositories are discussed.

The Hypertext Property Sheet

As discussed in the section on hypertext links, users will need the ability to select among a number of hypertext link publishers. The facility to search hypertext links is very similar to the mask searching facility. When the user clicks on the box labeled "Hypertext" a property sheet similar to the one shown below appears. The user can bring a hypertext link publisher search window similar to the author search window shown clicking on the box labeled "Search". After having that looks interesting, the user clicks on "Add" to add it to the "Hypertext" subwindow. Hypertext publishers are deleted using the "Delete" command. Particular hypertext link publishers are enabled/disabled by going to the "Hypertext List" and clicking on the box next to the publisher to toggle its state. The order of hypertext link publishers in the "Hypertext List" specifies the order in which hypertext links are searched for. Thus, when the user displays some text, they will see the text first, followed shortly thereafter by whatever hypertext links are associated with the text; thus, hypertext links from the top of the "Hypertext List" will show up more quickly than ones from the bottom of the list. The boxes labeled "Move Up" and "Move Down" are used to rearrange the order of entries in the "Hypertext List".

Hypertext Search Window

The Menu Property Sheet

Users will need the ability to quickly get to information that they commonly access. A customizable menu facility is one facility that will enable users to quickly get to commonly accessed information. By clicking on the box labeled "Customize", a menu customization property sheet similar to the one below is shown. Menus are hierarchical. The boxes labeled "Go Up One Menu" and "Go To Sub-menu" are used to go up and down the menu hierarchy. The boxes labeled "Move Menu Up One" and "Move Menu Down One" are used to rearrange the order menu entries. The boxes labeled "Cut/Delete Menu" and "Paste Menu" are used to move menu entries from one menu to another; this is accomplished by cutting a menu entry (using "Cut/Delete"), moving to another menu (using "Go Up/Down"), and pasting the menu entry (using "Paste") to the desired menu. New menu entries are appended to the current menu using the box labeled "Append New Menu Name". A menu is connected to an existing hypertext link via the box labeled "Connect Menu to Hypertext Link".

Customize Window

For example, to create the menu for "Newspapers", the user performs the following steps:

The "Newspapers" sub-menus is created by:
- clicking on "Go to Sub-menu",
- a pop-up appears asking the user to select the sub-menu from the current menu,
- the user clicks on "Newspapers",
- another pop-up appears asking the user to confirm whether a new sub-menu is to be created, and
- the user clicks on the box labeled "Yes".
The user adds the "Wall Street Journal" and "New York Times" to the menus by:
- typing "Wall Street Journal" into the enter area in "Append New Menu Name",
- clicking on the box labeled "Append New Menu Name", and
- entering "New York Times" the same way.
The user connects up the "Wall Street Journal" hypertext link as follows:
- in the main window, the user clicks on "Top" to get the top level menu,
- the user clicks on "Titles" to bring up the title index search window that looks like author search window,
- the user types "Wall Street Journal" into the search name text entry area and clicks on the box labeled "Search",
- the index entry labeled "Wall Street Journal" appears,
- in the menu Customization property sheet window, the user clicks on the box labeled "Connect menu to Hypertext Link",
- a pop-up appears asking the user to select a menu entry from the current list,
- the user clicks on the box labeled "Wall Street Journal" in the property sheet,
- another pop-up appears asking the user to click on the hypertext link in main window to be connected to,
- the user clicks on "Wall Street Journal" in the main window, and
- the connection to the "New York Times" is done the same way.

It goes without out saying that a human factors specialist will be able to improve upon this user interface.

The Render Property Sheet

The user can control how text is to be displayed by clicking on the box labeled "Render" to cause a window similar to the one below to be shown. With the "Render" property sheet, the user can select among the various categories of text (i.e. author, title, paragraph, footnote, etc.) and control the indentation, line spacing, and font characteristics (size, style, color, etc.)

Render Property Sheet

Viewer Software Installation

It is important that the viewer software be easy to install. Before the user can start browsing electronically published material, they will have to do the following:

Get the viewer software off of the distribution media (e.g. floppy disk, CD-ROM, etc.) and install it on the local hard disk.
As described in 5.0, the user needs to find an electronic bank. At installation time, the viewer software can provide a reasonably up-to-date list of electronic banks. The user can set up an electronic bank account by either visiting the electronic bank's office in person, or by postal mail. When the user visits the electronic bank in person, they bring cash or a money order to deposit and leave with an electronic checkbook floppy disk. If postal mail is used, the user print out an application form using their own printer, fill in the information, write a check against their own checking account, mail both to the electronic bank, and the electronic bank will mail an electronic checkbook floppy disk back to the user.
Some electronic banks will probably provide a stream-lined service whereby the user can call up, provide a credit card number, the electronic bank will ship a temporary electronic checkbook over the phone lines to the user's computer to be written onto a floppy disk supplied by the user. The electronic checkbook supplied by the electronic bank will arrive via the postal mail a few days later.
Once the user has an electronic bank account, a viewer software account can be set up by filling in the information shown in the account property sheet. The viewer software can provide a list of reasonably up-to-date cache phone numbers to select from.
The remaining property sheets can be preinitialized to contain reasonable values so that the user can get immediately start browsing electronically published information.
The user can be walked through the whole installation process using electronically published installation material; enough of this installation material would be shipped with the viewer software to get the user get "on-line."

Authoring Software

Whenever the user wants to author information for publication, they need to use authoring software. While the viewer software could provide its own authoring software, it probably makes more sense to let the user author their own material using the word processor of their choice and instead have the viewer software provide a capability for translating the information into the appropriate format for electronic publication.

For example, material can be written using Frame Maker, written out in Maker Interchange Format (i.e MIF) and some software can read the MIF file and produce the appropriate electronic format. References to other material can ...

Electronic Mail and Bulletin Boards

An electronic publication system should provide a means for users to communication between themselves using the system. Two common forms of electronic correspondence are bulletin boards and direct person-to-person mail.

Bulletin boards are the easiest to provide. Each user that wants to contribute material will publish it using their repository. A central location will contain a list of hypertext links to each piece of material posted to the electronic bulletin board. There is a certain elegance to having the cost of the bulletin board distributed amongst the bulletin board's contributors; of course, a heavily read bulletin board will actually generate revenue for its contributors. The only cost that must be maintained by the bulletin board itself is the cost of a queue of hypertext links.

Electronic direct person-to-person mail is a bit more difficult to provide since correspondence is generally private. Public key cryptography is a perfect match for this problem. A private message can be sent to someone by encrypting it with a public key and the publishing it via the same mechanism as electronic buxletin boards. Again, the user will need to bear the cost of a queue of hypertext links to information sent to them. The cost of the queue can be reduced by charging a royalty for inserting a hypertext link into it; this strategy should reduce the amount of "junk e-mail" that advertisers will attempt to send.

Viewer Software Summary

Hopefully, this whirl-wind tour of the viewer software has convinced you that the viewers software is feasible but will require a significant amount of work to produce.

You may go to the next chapter discussing repositories or back to the table of contents.