Requirements Analysis Using Event/Response and Use Cases: Analysis Sequence

Planning

Getting requirements right is a process. Your business stakeholders will rarely (if ever) be able to give you all of their requirements without some method of generating relevant questions to draw the requirements from them. What I am going to present in this and the following posts on this topic is NOT a new way to document your old thinking. It is a new way to think about requirements.

The deliverables created from this approach are:

  • Identification of all processes in scope
  • Documentation of the specific Use Cases for each process
  • Identification of all of the stakeholders that interact with the business processes
  • Creation of a framework with which you can generate and execute your test cases

Many analysts start and end their requirements elicitation with “functional requirements” (e.g. “I need to search by Last Name” or “Requests for time off need to be approved by the manager”). In the Event/Response/Use Case approach, functional requirements are derived from the Use Cases at the end of the analysis process.

The analysis sequence is as follows:

  • Business Objectives
  • Project Objectives (1st cut)
  • Event Model
  • Project Objectives (verified)
  • Use Cases
  • Functional Requirements

In the next post, I will discuss how the Business and Project Objectives are defined and used in the Event/Response methodology.

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Requirements Analysis Using Event Response and Use Cases: Overview

Initiation

This is the start of a multi-part series on my favorite requirements elicitation technique: the Business Event/Response Analysis. Early versions of this methodology were developed in the late 1980’s by some of the great system development minds of that era. Since then it has evolved and I have adapted it to meet the needs of whatever organization for which I am working.

There are some that think you can gather requirements by just asking the sponsors and users “what do you want?”. Needless to say, this method will generate incomplete requirements and tends to start and end with functional requirements. In the latter half of the project when large requirements gaps are discovered, the sponsors/users blame the analyst and vice versa.

When I teach on this topic, I tell the analysts it is their responsibility to gather complete requirements. Given this, we need a method that will (1) generate the appropriate questions to ask, (2) ensure that we have the complete set of requirements, and (3) allow us to derive the functional requirements from the model.

The Business Event/Response method meets these desired outcomes. The advantages are:

  • It helps the Business Analyst create the questions needed to draw the requirements from the Business Owner, even if the Analyst has no knowledge of the business area.
  • It organizes the requirements in the context of Business Processes and Usage to promote better understanding.
  • The output serves as a starting point for defining the testing scope and scenarios.

In the upcoming posts I will describe this method in detail.

Requirements Elicitation Techniques Part 5 – Data Modeling

Planning

Data modeling is a complex topic. Becoming a professional data modeler takes months or years of education plus practical experience. It is not my intent to teach data modeling in this brief post, but to show how it related to requirements elicitation.

I introduced some of the concepts of data modeling in Part 4 of this series, “Business Rules Analysis”. The relationships between entities are the business rules and they are fixed in the structure of the data. Examples of these rules are “A Customer lives at one or more Addresses” and “An Address may contain one or more Customers”.

Entities can be found in the nouns in your requirements. They are people, places and things about which the organization wishes to store data. In the example above, “Customer” and “Address” are entities and are therefore capitalized in the rules statements.

Attributes are the elemental pieces of data that are associated with each Entity. In the logical data model, each attribute must be stored with one and only one Entity. The logical data model represents the business Entities, Attributes and Relationships without regard to physical implementation.

The physical data model represents how the logical data model will be implemented in a relational database. Here are two examples of the differences between the logical and physical data models:

  • In the logical model, you can have “many to many” relationships as in the Customer / Address example above. In the physical model you cannot implement many-to-many relationships, so there would need to be an additional table to store each Customer / Address combination.
  • In the logical model,  Attributes belong to one and only one entity. In the physical model, attributes can be included in multiple entities due to inclusion on table keys or for performance reasons.

The data is an important part of requirements gathering. It is an important tool in Event Discovery, as you will ask data related questions such as “What does having this data allow you to do?” and “If I took this data away, what would it prevent you from doing?” I would recommend all Project Managers at least be able to read and understand an Entity-Relationship diagram.

Requirements Analysis Using Event/Response and Use Cases – Final Summary

Planning

In the preceding posts, I gave you some guidance on how to execute the Event/Response methodology for scope and requirements analysis. In this last of the series of posts on this topic, I will take the 5,000 foot view and put it all together in a summary of steps.

  • Step 1 – Define the Business Objectives (the measurable benefits realized after implementation). These will be used to verify the scope and requirements.
  • Step 2 – Define the Project Objectives (the products, services and/or results delivered at project implementation). These will also be used to verify scope and requirements.
  • Step 3 – The Context Diagram. Look at the area under study as an outsourced business, with Suppliers (of data) and Customers (recipients of data/information/results).
  • Step 4 – The Event List. This represents your “business model”. You define all of the events that “wake up” your business and require a planned response. In the prior posts, I presented a variety of techniques for fleshing out these events. Included in the Event List are your business processes and stakeholders.
  • Step 5 – Validate the Event Model. Compare your event scope with the Business and Project Objectives and verify with the Project Sponsor that all objectives are covered by this scope.
  • Step 6 – Construct Use Cases. Use the defined business processes in the Event Model as the starting point for creating Use Cases.
  • Step 7 – Test Planning and Execution. The Event Model is a wonderful framework in which to define your test scenarios and cases. Take advantage of all the work you did in the requirements phase to make your test planning and execution easier.

That’s it for this topic. I hope you found it informative and useful. I have used this technique successfully in many real-world projects.

Requirements Analysis Using Event/Response and Use Cases – Test Planning and Execution

Planning

In addition to being a great way to elicit the complete scope of a project, the Event/Response methodology delivers a framework for test planning and execution. When using this methodology, what many call “User Acceptance Testing” can be replaced by the term “Event Testing”.

In my prior posts on this topic, I identified the primary deliverables of the Event/Response methodology as (1) the Event List (containing the event that triggers the response, the origin and data content of the information flow into your “business”, the named processes, the outputs of the processes and the destinations of the outputs) and (2) the Use Cases. You can plan to test by simulating the actual Events, creating the data flows, executing the processes and examining the outputs. The Use Cases give you a good start on creating the data and usage variations for each Event. Doing this yields a direct mapping of the scope and requirements to the test cases and execution.

Note that since the Event List also contains the roles of the actors initiating the events, as well as the roles receiving the outputs, security testing is also built into this framework.

Another major plus of planning and executing the tests this way is that you are testing the system as it will actually be used in context, as opposed to functional testing which tests bits of functionality in isolation.

A recent project of mine used this methodology and yielded 180 Events and over 1,600 test cases. Because of this comprehensive approach, the system was very well tested and only experienced minor problems after implementation.

Requirements Analysis Using Event/Response and Use Cases – Functional Requirements

Planning

In my previous post on the topic of Requirements Analysis, I showed you how to derive your Use Cases from the Event List. I also presented a list of recommended elements to be included in each Use Case. The primary element is the list of steps taken by the Actors and the System they interact with. Within these steps are the Functional Requirements.

In my initial post in this series, I mentioned that starting and ending requirements gathering with functional requirements was not very effective. Why? Because functional requirements are at too low of a level and places the burden on the memories of SME’s (Subject Matter Experts) instead of the analytical questions of the Business Analyst, where the burden really belongs. For large systems, if you start and end with functional requirements you will almost assuredly have an incomplete set of requirements.

Using the Event/Response methodology, we started with Event Discovery, using a wide variety of techniques to generate the questions the Business Analyst needs to ask. We fleshed out the Events, which led to discovery of the business processes in scope. We validated the model to make sure we had the complete list of Events and processes. We used the processes to create our Use Cases. We will now examine the Use Cases to derive the functional requirements. This is an organized, top down approach to requirements that will output as complete a set of requirements as is possible.

Within the steps of the Use Cases are things like “Insert Debit Card”, “Read Card”, “Select Action”, “Browse by Last Name”, etc. These are all functional requirements that must be satisfied by the solution. The system design must address all of these requirements. However, these are low-level capabilities and are not a good source for overall system design. By using the Event Model, the system designer can see the big picture and design a friendlier, more efficient system than is possible using just the functional requirements.

In the next post I will address the advantages of the Event Model when designing and executing tests.

Requirements Analysis Using Event/Response and Use Cases – Use Cases

Planning

Now that you have a complete and comprehensive Event List, you can now use this to create your Use Cases. Before I show you how, let’s first define “Use Case”:

  • A Use Case is simply a list of steps to achieve a goal
  • It may have multiple paths (for example, the Use Case for getting cash from an ATM has the normal path, plus an alternate path for the case where a user asks for more money than in their account)
  • A Use Case Scenario is a specific path thru the Use Case

Column 4 of the Event List (“…Then We Do This”) contains the names of all of the business processes within the scope of your project. Take each of these process names and create a corresponding Use Case. Here is a collection of data elements which you can include in the Use Case:

  • Use Case Name and ID (you can use a scheme such as capital U + the Event Process ID + decimal point + the Use Case sequential number. For example, U2.1.1)
  • Use Case brief description (The process name and perhaps an additional clarifying sentence or two)
  • Sub-System Name (e.g. “Accounts Payable”)
  • Triggering Event (from the Event List)
  • “Actors” (Stakeholders that interact with or are affected by the Use Case; Your Event List is a great starting point for identifying your Stakeholders)
  • Pre-conditions: What needs to be true before the execution of this Use Case (for example, “Customer ID has been established”)
  • Post-conditions: The state of the system after execution of the Use Case (for example, “Employee has possession of a company credit card”)
  • Process Flow. Include a column for the Actors and a column for the steps executed by the Actors and the System. Do this until the process is complete and accomplishes the Post-conditions.

In the next post I will discuss deriving Functional Requirements from the Use Cases.