Chapter 9: the Forms of Resource Descriptions

Chapter 9 The Forms of Resource Descriptions Ryan Shaw Murray Maloney 9.1. Introduction . 467 9.2. Structuring Descriptions . 469 9.3. Writing Descriptions . 492 9.4. Worlds of Description . 501 9.5. Key Points in Chapter Nine . 508 9.1 Introduction Throughout this book, we have emphasized the importance of separately consid ering fundamental organizing principles, application-specific concepts, and de tails of implementation. The three-tier architecture we introduced in §1.6 is one way to conceptualize this separation. In §6.7, we contrasted the implementation-focused perspective for analyzing relationships with other per spectives that focus on the meaning and abstract structure of relationships. In this chapter, we present this contrast between conceptualization and implemen tation in terms of separating the content and form of resource descriptions. In the previous chapters, we have considered principles and concepts of organ izing in many different contexts, ranging from personal organizing systems to cultural and institutional ones. We have noted that some organizing systems have limited scope and expected lifetime, such as a task-oriented personal or ganizing system like a shopping list. Other organizing systems support broad uses that rely on standard categories developed through rigorous processes, like a product catalog. By this point you should have a good sense of the various conceptual issues you need to consider when deciding how to describe a resource in order to meet the The Discipline of Organizing goals of your organizing system. Considering those issues will give you some sense of what the content of your descriptions should be. In order to focus on the conceptual issues, we have deferred discussion of specific implementation issues. Implementation involves choosing the specific form of your descriptions, and that is the topic of this chapter. We can approach the problem of how to form resource descriptions from two perspectives: structuring and writing. From one perspective, resource descrip tions are things that are used by both people and computational agents. From this perspective, choosing the form of resource descriptions is a kind of design. This is easy to see for certain kinds of resource descriptions, notably signs and maps found in physical environments like airport terminals, public libraries, and malls. In these spaces, resource descriptions are quite literally designed to help people orient themselves and find their way. But any kind of resource descrip tion, not just those embedded in the built environment, can be viewed as a de signed object. Designing an object involves making decisions about how it should be structured so that it can best be used for its intended purpose. From a design perspective, choosing the form of a resource description means making decisions about its structure. In §6.5, we took a structural perspective on resources and the relationships among them. In this chapter, we will take a structural perspective on resource descriptions. The difference is subtle but important. A structural perspective on resource relationships focuses on how people or computational processes asso ciate, arrange, and connect those resources. A structural perspective on re source descriptions focuses on how those associations, arrangements, and con nections are explicitly represented or implemented in the descriptions we cre ate. Mismatches between the structure imposed on the resources being organ ized and the structure of the descriptions used to implement that organization could result in an organizing system that is complex, inefficient, and difficult to maintain, as you will see in our first example (Example 9.1, Description struc tured as a dictionary). The structures of resource descriptions enable or inhibit particular ways of in teracting with those descriptions, just as the descriptions themselves enable or inhibit particular ways of interacting with the described resources. (See §3.4 Designing Resource-based Interactions (page 127), and Chapter 10, Interac tions with Resources) Keep in mind that resource descriptions are themselves information resources, so much of what we will say in this chapter is applicable to the structures and forms of information resources in general. Put another way, the structure and form of information resources informs the design of re source descriptions. From another perspective, creating resource descriptions is a kind of writing. I may describe something to you orally, but such a description might not be very 468 Chapter 9 — The Forms of Resource Descriptions Professional Edition useful to an organizing system unless it were transcribed. Organizing systems need persistent descriptions, and that means they need to be written. In that sense, choosing the form of a resource description means making decisions about notation and syntax. Modern Western culture tends to make a sharp distinction between designing and writing, but there are areas where this distinction breaks down, and the creation of resource descriptions in organizing systems is one of them. In the following sections, we will use designing and writing as two lenses for looking at the problem of how to choose the form of resource descriptions. Specifically, we will examine the spectrum of options we have for structuring descriptions, and the kinds of syntaxes we have for writing those descriptions. 9.2 Structuring Descriptions Choosing how to structure resource descriptions is a matter of making princi pled and purposeful design decisions in order to solve specific problems, serve specific purposes, or bring about some desirable property in the descriptions. Most of these decisions are specific to a domain: the particular context of appli cation for the organizing system being designed and the kinds of interactions with resources it will enable. Making these kinds of context-specific decisions results in a model of that domain. (See §5.3.1.2 Abstraction in Resource Descrip tion (page 251).) Over time, many people have built similar kinds of descriptions. They have had similar purposes, desired similar properties, and faced similar problems. Unsur prisingly, they have converged on some of the same decisions. When common sets of design decisions can be identified that are not specific to any one do main, they often become systematized in textbooks and in design practices, and may eventually be designed into standard formats and architectures for creat ing organizing systems. These formally recognized sets of design decisions are known as abstract models or metamodels. Metamodels describe structures com monly found in resource descriptions and other information resources, regard less of the specific domain. While any designer of an organizing system will usu ally create a model of her specific domain, she usually will not create an entirely new metamodel but will instead make choices from among the metamodels that have been formally recognized and incorporated into existing standards. The re sulting model is sometimes called a “domain-specific language.” Reusing stand ard metamodels can bring great economical advantages, as developers can re use tools designed for and knowledge about these metamodels, rather than hav ing to start from scratch. In the following sections, we examine some common kinds of structures used as the basis for metamodels. But first, we consider a concrete example of how the structure of resource descriptions supports or inhibits particular uses. As we 9.2 Structuring Descriptions 469 The Discipline of Organizing Figure 9.1. A Batten Card. An example of a punch card used by Batten to describe a particular patent in a patent collection. Each card represented an individual description term, and each punch position on a card represented a particular patent. explained in Chapter 1, the concept of a resource de-emphasizes the differences between physical and digital things in favor of focusing on how things, in gener al, are used to support goal-oriented activity. Different kinds of books can be treated as information resources regardless of the particular mix of tangible and intangible properties they may have. Since resource descriptions are also information resources, we can similarly consider how their structures support particular uses, independent of whether they are physical, digital, or a mix of both. During World War II, a British chemist named W. E. Batten developed a system for organizing patents.516[Com] The system consisted of a language for describing the product, process, use, and apparatus of a patent, and a way of using punched cards to record these descriptions. Batten used cards printed with ma trices of 800 positions (see Figure 9.1). Each card represented a specific value from the vocabulary of the description language, and each position correspon ded to a particular patent. To describe patent #256 as covering extrusion of pol ythene to produce cable coverings, one would first select the cards for the val 470 Chapter 9 — The Forms of Resource Descriptions Professional Edition ues polythene, extrusion, and cable coverings, and then punch each card at the 256th position. The description of patent #256 would thus extend over these three cards. The advantage of this structure is that to find patents covering extrusion of pol ythene (for any purpose), one needs only to select the two cards corresponding to those values, lay one on top of the other, and hold them up to a light. Light will shine through wherever there is a position corresponding to a patent de scribed using those values. Patents meeting a certain description are easily found due to the structure of the cards designed to describe the patents. Of course, this system has clear Punchcard Machine disadvantages as well. Finding the concepts associated with a particular patent is tedious, be cause every card must be inspec ted. Adding a new patent is rela tively easy as long as there is an index that allows the cards for specific concepts to be located quickly. However, once the cards run out of space for punching holes, the whole set of cards must be duplicated to accommodate more patents: a very expensive Punchcards were an important informa operation.

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