In the beginning stages of developing an e-business system, many stakeholders must contribute requirements, domain model details for the analysis, and specifications for design and implementation. This book does not attempt to cover the full development lifecycle but instead focuses on analysis and some parts of design, all with an eye toward the use of XML. Within this context, we must consider the needs of several diverse stakeholder communities. I have narrowed the focus for this book to five groups: consumers, business analysts, Web application specialists, system integration specialists, and content developers.
A complete analysis of an e-business system would require documenting many different use cases that describe the convergence of these stakeholder communities in B2B and business-to-customer (B2C) interaction scenarios. Figure 1-1 illustrates one high-level use case diagram that incorporates all five of the identified stakeholder communities. This high-level view spans the requirements from designing the product catalog structure and content to presenting personalized views of this catalog to consumers.
A use case specification identifies a set of "actors" that interact with each use case. Each actor represents the role of a user that works with the resulting system after it is deployed; a specific human user may fulfill several different roles. As shown in Figure 1-1, UML use case diagrams always represent an actor using a "stick person" icon. Each oval represents an individual use case that describes (in a separate document and/or diagram) the activity flow required to achieve the goal of that use case. The use case diagram presents an outside view (from the perspective of the actors) of the system without specifying how that functionality is designed or implemented.
I use the term stakeholder rather than actor in this description because of its broader meaning. A stakeholder represents all roles that have an interest in the goals of a use case, not only those who directly participate in performing the use case activities. Thus, a Consumer stakeholder provides requirements for the design of portals and business processes, although he or she may not have a direct role in performing the steps within those use cases.
Future chapters will decompose the individual use cases into scenarios illustrated with class diagrams, object diagrams, sequence diagrams, and activity diagrams that specify how XML fits into the overall e-business solution. But first, I'll describe the typical characteristics of each stakeholder community in a bit more detail.
A consumer may be either a business customer in the supply chain (for example, a buyer of components for a manufacturer) or an end-user retail customer. I use the term consumer rather than customer to emphasize that consumption occurs at many points along the e-business supply chain. In many current situations, this consumer represents a human user who is interacting with the product catalog service. However, we will increasingly see automated consumer agents, also called 'bots (a truncated form of the word robot), that fulfill the consumer role. A B2B consumer may be an automated order submission process triggered by the production schedule, or a retail consumer may be represented by an automated shopping agent that performs comparison shopping across sites.
The use case diagram shows the consumer as a stakeholder in both designing the business processes and in designing the portal's personalized views of the catalog. The business processes for business consumers are very different from those supporting retail customers. Therefore, the use case diagram includes two more specialized use cases that extend the general use case for designing business processes. During requirements analysis of a B2B service, representative consumers must be included, either in individual interviews or as part of larger focus groups. This input would be documented in text documents associated with the relevant use cases and in activity or sequence diagrams of the event flows.
The difference in requirements for human or 'bot consumers is unspecified in this high-level use case diagram. Their different requirements would need to be described in the individual use cases, or likely in additional sub-use cases that define the specialization. For example, both a human and an automated 'bot consumer require a personalized presentation of the catalog, but the means of personalization may be quite different. A human user would expect an HTML browser-based presentation that is tailored to his or her preferences and supports quick navigation without a lot of distracting, irrelevant information. On the other hand, a 'bot may expect a filtered subset of the catalog content that is tailored to its particular interests as a buyer. Of course, either of these kinds of personalization can be enabled by effective use of XML.
In the context of an XML application, consumers are both sources and recipients of communication. As a source, the consumer produces XML-based messages containing product catalog queries, requests for quotes, or orders. A consumer receives product catalog information encoded in XML documents, which is then presented in a Web browser or imported into the recipient's business system. Both scenarios are covered in later chapters.
The use case diagram in Figure 1-1 depicts the business analyst as being central to implementing a successful e-business application. The analyst participates in each of the use cases, often as the integrative force and visionary for the overall system. The business analyst also collaborates with the content developer to create the domain model for the product catalog. Other stakeholders such as marketing, sales, and accounting would be included in a full requirements analysis. The analyst then works with the Web application specialist to design a dynamic, personalized Web site for this product catalog.
Figure 1-1 e-Business stakeholder interactions
The business analyst uses this knowledge of the product catalog model to collaborate with the system integration specialists. System integration requirements include adaptation of legacy systems into this new e-business application at multiple stages of both B2B and B2C business processes, plus integration with other external systems such as credit authorization and shipping.
The business analyst uses his or her knowledge of the overall e-business environment to oversee the requirements gathering process for an integrated solution. He or she must understand the process for using the UML in use case and activity modeling and be able to facilitate design of the UML static structure models that represent the XML vocabularies for system integration and Web presentation. This last modeling responsibility is the central topic of this book.
Web Application Specialist
A Catalog Exchange Service (CatX) is analyzed as a sample application in this book. For the CatX system, Web application specialists are most often concerned with the portal server component and portal requirements and design. But this is no simple matter! We are still very early in the maturity of XML processing directly within Web browsers. So for the next year or two, it's likely that much of the Web application processing for XML content will be executed within application servers. For example, Java servlets may process the XML catalog content, using an XSLT transformation to produce HTML content for the e-marketplace portal interface.
There are many sub-roles within the community of Web application specialists. Dynamic server pages have become the mainstays of Web development; for example, the J2EE standard for JavaServer Pages (JSP), Microsoft's Active Server Pages (ASP), or Allaire's ColdFusion. These technologies are often used to process XML content for Web browser delivery. However, XML is also introducing new technologies into the Web developer's toolkit. The Extensible Stylesheet Language (XSL) is now used in combination with Cascading Style Sheets (CSS) to transform and format XML documents for presentation on the Web. These topics are discussed in later chapters as part of designing XML portals.
Jim Conallen's book [Conallen, 2000] examines the broader details and alternative architectures for designing Web applications. I focus attention on the analysis and design of XML content within e-business solutions. Chapters 2 and 5 explore the use of XML by Web application specialists and introduce the benefits of UML from their perspective.
There are also many exciting new developments in wireless Internet access via mobile phones, PDAs, and other specialized Internet devices. In most cases, XML plays a significant, if not dominant, role in communicating information to and from these wireless devices. This new stakeholder role fits most closely with the skills of advanced Web application specialists but will also require development of new skills. I'll have more to say about this subject in later chapters, particularly regarding the use of XSLT to transform XML catalog content for presentation by the wireless world.
System Integration Specialist
System integration specialists play a very significant role in B2B e-commerce. It is almost a certainty that one will encounter several incompatible systems when integrating e-business processes across several organizations in a supply chain or marketplace. Prior to the availability of XML, the most common solutions were to attempt development of standard APIs using technologies like CORBA, RMI, or DCOM, or to adopt message-oriented middleware that supported reliable, asynchronous routing and delivery of data and events. These approaches proved difficult and expensive to implement in a widely distributed, heterogeneous environment using the public Internet for transport and did not have a good solution for formatting the large blocks of structured data contained in the message's body.
XML-enabled applications take a very different approach to integration. Instead of standardizing the APIs for system integration, the data format is standardized for text-based documents exchanged among participants. This is sometimes referred to as platform-independent data, which complements the Java programming language as platform-independent code for a complete, vendor-independent integration solution.
Use of XML for the content format allows these documents to be parsed and transformed with the use of standards-based tools that are very inexpensive, or often free. Thus, exporting and importing XML documents has become a common means for integrating otherwise incompatible systems. Many B2B integration solutions are now adopting a hybrid of message-oriented middleware, carrying XML structured content in the message body.
These are all primary tasks within the domain of system integration specialists. The use case diagram shown in Figure 1-1 includes one use case for integrating B2B transactions. Obviously, there are many details yet to be explored in these requirements. Chapters 3 and 4 introduce the use of UML for modeling business processes and the XML vocabularies required for B2B integration.
Within a large organization, hundreds of people may be involved in developing catalog content in the form of product specifications, price lists, white papers, frequently asked question (FAQ) lists, and so on. Since all of this content is potentially useful in a B2B service, the content developers must be involved in specification of the catalog vocabulary. These stakeholders will be consulted in upcoming chapters as we construct the UML models for the required behavior and structure of the XML documents.