Synergistic Solutions, Inc. (SSI) is a vendor of EAI software for telecommunications companies. Their products focus on customer provisioning of high-capacity services such as DS1 and DS3, developing systems that provide a unified, GUI interface to legacy applications (Operational Support Systems, mostly). Their systems pull together information from many legacy systems and present it to design engineers so those engineers don't have to deal with multiple systems, because there is a huge learning curve on those legacy systems.
SSI called upon System Innovations when their products had been accepted by a major telecommunications company, with the one provision that those products would be designed and documented in UML, with particular emphasis on the product architecture. The purchasing company told SSI they would require a stringent review of SSI's product architecture, as delivered in the Unified Modeling Language.
The examples that follow include some of the models that were developed for SSI's product suite. They were originally published with permission in Laura's book, Integration Models: Templates for Business Transformation.
Layers of code add to complexity
NetFlow is a product SSI makes that helps correct problems in the administration of hardwired elements in the Operational Support Systems (OSS) that are commonly used to administer them. These OSS systems are not designed to handle certain configurations of network elements that actually occur in the field, with the result that there are interruptions to the flow of the process of managing those disallowed configurations. The NetFlow product helps design engineers by identifying those configurations, "fixing" their entries in a special database, and informing the OSS of their existence.
The model shown in Figure 2 was developed to capture the use cases that describe the desired functionality of the NetFlow product. It uses the Tree structure to depict the possible branches in functionality, ending in more detailed possibilities on the right side of the diagram.
The NetFlow Use Case Tree defines the desired functionality for a middleware product.
The highest level of function for this product is the administration of hardwired elements. That function is composed of the following sub-functions:
- Build and maintain the hardwired database
- Poll and manage the work list that conveys the information from and to the legacy systems
- Find hardwired elements
Under the "build and maintain the hardwired database" function, the "build database" function is composed of the following:
- One-time automatic build
- Manual build
The "maintain database" function includes the following:
- Update based on Cable Pairs job
- Update as found in the field
Finding hardwired elements consists of finding and posting the service order so that it flows properly through the process for the variety of possible configurations (F1 Cable Pairs hardwired to Object Repeater Bay to Multiplexer, Object Repeater Bay to Multiplexer, and so forth).
The Use Case Tree provides encapsulation of functionality at a high level. A similar Use Case Tree is developed to capture all requirements for error-handling and error message processing. Use Cases are subsequently resolved into collaboration diagrams, which depict one scenario for each significant use case. Scenarios model the objects that collaborate to deliver those use cases. To show how NetFlow works, the team develops a generic model of the core middleware that controls processing of NetFlow, which is a product called the Business Process Server (BPS).
Need for non-linear modeling techniques
The BPS is a generic support process, which accesses a common database, developed in Oracle, to configure its rules, queues, and external interfaces based on the start-up command line. When running, the BPS spawns the pre-determined number of remote system interface processes, which can interface with remote systems with a number of protocols including EHALAPI, sockets, and ODBC. The BPS loads and executes the pre-determined business rules for its start up defined role.
Class diagrams and collaboration diagrams are used to specify the components of the BPS and show how they collaborate. Then those components are reused in the collaboration diagrams that depict the scenarios for another SSI product, the NetLocate system, seen in Figure 3.
The NetLocate collaboration diagram shows how this EAI product accesses remote data sources through pre-defined BPS components.
The non-linear and self-referential nature of the BPS is modeled and captured in class diagrams so that components can be reused in collaboration diagrams.
Interfaces and metadata
As is the case for many EAI products, NetLocate and NetFlow provide interfaces to legacy systems that maintain intricate rules (or metadata) for accessing data and functions inherent to the legacy systems. EAI products providing access to legacy data can be modeled with the introduction of a UML metadata class type, which stores the rules for data access.
Other EAI features provide a unified front-end to the functionality of legacy systems. UML architecture models can utilize the Facade class to model these front ends, introduced by Gamma et al in the book, Design Patterns: Elements of Reusable Object-Oriented Software. Similar to the more familiar concept of database views, the Facade class can be used to depict a window upon functionality resident in legacy applications.
Customized reuse of product components
SSI uses a layered UML model to depict the system blueprint diagram for its NetLocate product. The model in Figure 4 helps the client purchasing this system to understand the intended architecture and what will be required to deploy the product in a particular environment. It also helps SSI reuse the components of existing products to formulate customized new products for clients.
Synergistic Solution's NetLocate product models the system's component architecture in UML.
The NetLocate system blueprint diagram organizes the components of the system into layers, including:
- Application specific
- Oracle-stored procedures that are used to access the Oracle database and the database belonging to certain remote systems from which NetLocate retrieves data.
- Application general
- Web browser and HTML coding used to provide user access to the retrieved data.
- Components specific to the NetLocate product, such as application and Web servers, and program DLLs and executables required to provide system functionality.
- System software
- Operating system and Oracle database management system.
The layered model shows the required components from the architecture viewpoint. Subsequent models, such as the component responsibility model, reorganize the components according to their interaction and the functionality they collaborate to deliver.