|The goal of this thesis is to examine the usability of current directory standards in the context of workflow-supporting office platforms. As a basis, in chapter 2, an infrastructure model comprising objects that are relevant for a directory service, is developed. It can be utilized both by workflow management applications in order to assign persons or organizational units to tasks as well as by directory services to provide users with information about the organization.
Chapters 3 and 4 introduce the most important standards for directory services, the X.500 standard recommendations of the ITU, and LDAP, the lightweight directory protocol, developed at the IETF. X.500 defines a full directory service, including an information model, concepts for distribution, access control and authorization as well as management and administration facilities. The various protocols defined in the standard are fully integrated into the OSI architecture, what complicates the development of X.500 clients and servers for non OSI environments. LDAP was developed to ease the access to X.500 directories. It is a simplification of the access protocol and does not provide a complete directory service in its current version. However, improvements in future versions move in this direction. In contrast to native X.500, LDAP meets wide acceptance in the industry and is supported by many groupware platforms and internet environments.
In chapter 5, the directory standards are confronted with the requirements defined in chapter 2. The X.500 information model is examined for the capability of representing the infrastructure model developed before; security and distribution concepts are evaluated in the context of workflow management environments. The result is entirely positive. Most parts of the infrastructure model can be mapped onto predefined objects, the missing objects classes and attribute types can be specified very flexibly. The distribution and security concepts of X.500 are very sophisticated and meet all requirements.
After the positive judgement of the X.500 concepts, the options for an implementation of an X.500 conform directory service in a groupware environment are examined. Lotus Notes, the standard platform for groupware and workflow applications, unfortunately does not support any standard protocol in the current version. Gateways and external directory products have to be used to publish directory information stored in Notes. However, Lotus announced full LDAP support for releases to come later this year. This will allow to access directory information residing on any LDAP server using a Notes client. Likewise, any LDAP client may directly access directory information stored in Notes. Using a particular gateway, even X.500 DUAs and DSAs can communicate with Notes servers. An architecture like this would perfectly fit into modern workflow management system environments.
To summarize the result of this thesis, it can be said that the X.500 concepts are open, flexible and powerful enough to serve as directory backbone for workflow-supporting office platforms. The weaknesses of X.500, which are the integration in the complex OSI architecture and the complexity of its protocols may be compensated by LDAP in the future. Another possible direction is that LDAP more and more evolves to a complete directory service and pushes away its big brother. The next version of LDAP will allow LDAP servers to communicate with each other in order to forward requests and replicate information. This evolution in connection with the wide acceptance LDAP has met could actually make it the future directory standard.
In the context of workflow management and organization modeling both scenarios fit well. A standard for storing and accessing directory information is likely to come, and the leading platforms will support it. Be it LDAP or X.500, both are open enough to allow the implementation of powerful flexible organization models. Emphasis may be put to improve these models to both provide powerful directory services and serve workflow management systems in order to optimize the support of business processes.
In order to continue the research in this environment, several further steps can be made. The infrastructure model steadily has to be improved, especially considering workflow management systems that start to cross company borders and explore the Internet. Furthermore, as soon as Notes support for LDAP is available, pilot projects should be launched to evaluate the product. Critical issues are the flexibility of the implementation and the LotusScript interface to LDAP.