Systems Analysis and Design 06: Process Specification & Structured Decision

Summary

This video discusses process specification methods, focusing on structured English, decision tables, and decision trees. It explains each method's structure, usage scenarios, and how to choose between them. Structured English is used for repetitive actions, decision tables handle complex conditions and rules, while decision trees highlight the sequence of events. The video also touches on error handling in decision tables and briefly introduces the object-oriented approach and UML for process analysis, but focuses primarily on data flow diagram (DFD) modeling. The session concludes with a reference to further reading in Chapter 2 on use case modeling.

Takeaways

• 📊 Structured English is a method for process specification, using English in a structured pattern for clarity in process flow.
• 🔄 There are four main structures in Structured English: Sequential, Decision, Case, and Iteration.
• 📝 Sequential structure involves actions performed in a sequence, like action 1 followed by action 2.
• ❓ The Decision structure uses if-else conditions to determine actions based on true or false evaluations.
• 🧩 Case structure involves mutually exclusive actions, meaning only one can occur depending on the conditions.
• 🔁 Iteration structure involves repeating actions until a condition is no longer met.
• 📦 A decision table helps in specifying processes by laying out conditions and corresponding actions in a tabular format.
• 🌳 Decision trees help specify processes based on sequences of events, useful when actions need to follow specific conditions.
• 📊 Decision tables are ideal for complex combinations of conditions, avoiding contradictions and redundancy.
• ⚙️ Object-oriented approaches like UML focus on entity objects and are not the main focus here, but were briefly mentioned for comparison.

Q & A

What are the three approaches for process specification mentioned in the video?

The three approaches for process specification are Structured English, Decision Tables, and Decision Trees.

What is Structured English and how is it used in process specification?

Structured English is a process specification approach that uses a simplified version of English with structured delivery patterns. It helps describe processes in a clear, logical way, using sequential, decision, case, or iteration structures.

Can you explain the four structures used in Structured English?

The four structures in Structured English are: (1) Sequential structure, which describes a process in sequence (action 1, action 2, etc.); (2) Decision structure, where conditions determine which action to take; (3) Case structure, where different actions are taken based on specific cases; and (4) Iteration structure, where actions repeat while a condition is met.

What is a Decision Table and how is it used?

A Decision Table is used to show conditions, alternative conditions, and actions for each combination of conditions in a tabular format. It helps map out complex logic by organizing possible conditions and corresponding actions.

What are some special situations that can arise when creating a Decision Table?

Special situations in Decision Tables include: (1) Combining similar rules; (2) Adding new rules that affect the entire table; (3) Avoiding logically impossible conditions; and (4) Preventing contradictions and redundancy in the rules.

When should you use a Decision Tree instead of other forms of process specification?

A Decision Tree is used when the sequence of conditions and actions is important, or when not all conditions are relevant to all actions. It visually represents decisions based on the sequence of events.

What are some common uses for Structured English in process specification?

Structured English is typically used when there are repetitive actions or when clear communication with users is important, making it easier to describe step-by-step processes.

How do Decision Tables help avoid contradictions and redundancies?

Decision Tables help avoid contradictions and redundancies by clearly organizing conditions and actions. Similar rules can be combined, and special attention is given to ensuring that no conflicting or repeated rules exist.

What is the importance of determining the processing type before choosing a specification form?

It is important to determine whether the process will be executed online, in batches, or manually before choosing a specification form, as this affects how the process will be structured and documented.

How does the object-oriented approach differ from the other process specification methods mentioned?

The object-oriented approach focuses on entity objects and database-based data, using Unified Modeling Language (UML) to describe processes through use cases, which differs from the data flow modeling methods focused on in the video.