The following sections detail the analysis and design of the EZ Coffee Brewer system. Importantly, six analysis models and three design models were selected in the exploration of the given problem statement. The analysis models covered are the use case diagram, use case scenarios, class model, context diagram, data flow diagram (level 1), and statechart diagram. The design models covered are the class, responsibilities, and collaboration (CRC) cards; collaboration diagram; and subsystem diagram. 

For analysis, the use case model was chosen to understand the primary usages of the system by the user. This allowed the team to focus on only the most important functionality throughout the project. The use case scenarios were used to fully understand the process of setting up the machine and brewing the coffee from start to finish to ensure consistency across different models for the remainder of the analysis and design. Similarly, the class diagram was used to understand the various components of the system and how they exist in relation to one another. Identifying interdependencies and interactions here was vital in beginning to draft collaborations in the design phase of the project. On the other hand, the context, data flow, and statechart diagrams were drafted to understand the technical functionality of the coffee machine. These were based on the use case scenarios previously drafted. 

For the design phase of the project, a primary interest was placed on the CRC cards and corresponding collaboration and subsystem diagrams. By taking ample time to iterate and fully draft these models, a thorough understanding of the implementation classes and their collaborations was achieved. 

Importantly, all models and methods were created within a three-week time period. The analysis models were first drafted, followed by the design models. However, after the first drafts were completed, the analysis and design models were iteratively fleshed out to ensure consistency throughout the project. 

Several assumptions were made throughout the process. These assumptions are listed below. 

Assumptions: 

1) The coffee machine may enter a pairing state by holding down the On/Off Button. This assumption is used in the development of the CRC cards. 

2) The user does not need to obtain the phone application to accomplish brewing and setting up the machine, though the phone application may be used to initiate the process if desired. 

3) The warmer plate may be turned on by quickly tapping the power button on the coffee machine if the user does not wish to enable the warmer plate through the phone application. 

4) The coffee machine does not allow the user to brew coffee without any water available for brewing. At least one cup of water must be poured into the coffee machine to allow brewing to occur. 

This section details the two scenarios written for the two primary use cases. The primary use cases, Brew Coffee and Set Up Coffee Machine, are initially referenced in the use case diagram above. 

The class model displays all components of the system as object classes. Additionally, the model displays the attributes and behaviors of each class, as well as the interactions between each object. The Coffee Machine class is shown in the center of the model, which represents the physical coffee machine. Because the coffee machine is an aggregation of several components, the Warmer Plate, Water Scale, Light Indicator, Coffee Machine Display, Water Strainer, and Filter holder are all aggregates of the Coffee Machine. 

The Statechart Diagram displays the many states of the system and how they’re interacted with. This diagram shows how to navigate through each one and what each state does while active. 

By combining the identified classes and the contracts, the following CRC cards and the corresponding responsibilities of each class are generated. 

The collaboration diagram shown below reflects the CRC card design. The same classes and contracts are shown as represented by the CRC cards. The collaboration diagram provides a visual representation of the CRC cards to aid in visualizing and understanding the design presented. Additionally, the collaboration diagram effectively displays the interactions between classes, showing where each collaboration occurs. 

This webpage details the successful analysis and design of the EZ Coffee Brewer system. The work detailed in this webpage involved multiple revisions and iterations to achieve consistency with both the problem statement and other created models, and several challenges were seen throughout the process. Interestingly, the team retains confidence that the unique design may be successfully implemented in future stages of the project. 

The biggest challenge faced by the team was ensuring agreement between the different models, such as making certain that the process indicated through the statechart diagram agreed with the steps for coffee brewing indicated in the use case scenarios. Additionally, this was the first time the team received exposure to both analyzing and designing a system from one given problem statement from start to finish, and it therefore took a significant amount of time to ensure correctness, especially with the design models. If the team were to receive a new problem statement, there is significant certainty that the process would be expedited. 

The CRC process was particularly challenging due to the complexity of the system. Although the domain of the system was well scoped, the collaboration diagram nonetheless contained a high number of interdependencies and identified classes, which emphasize the complexity of the system. As additional classes were added to the CRC cards whenever necessary, the complexity of the design continued to grow. However, the team successfully documented the design and ensured both completeness and agreement between the CRC cards, the collaboration diagram, and the subsystem diagram. 

If the project were to be completed again with a new problem statement, the team would spend additional time increasing the cohesion and decreasing the coupling of the design in particular. The relatively high amount of coupling in the collaboration diagram is manageable and implementable, but clearly retains room for improvement.