srs doc for ecommerce, Exams of Business Systems

Download srs doc for ecommerce and more Exams Business Systems in PDF only on Docsity! Software Requirements Specifications Document CS3911 Software Requirements Specification (SRS) Template Items that are intended to stay in as part of your document are in bold; explanatory comments are in italic text. Plain text is used where you might insert wording about your project. The document in this file is an annotated outline for specifying software requirements, adapted from the IEEE Guide to Software Requirements Specifications (Std 830-1993). Tailor this to your needs, removing explanatory comments as you go along. Where you decide to omit a section, you might keep the header, but insert a comment saying why you omit the data. /app/work/qhbc04-srs_template2.doc Page 1 of 30 09/27/20 f Software Requirements Specifications Document CS3911 (Team Number) (Team Name) Software Requirements Specification Document Version: (n) Date: (mm/dd/yyyy) /app/work/qhbc04-srs_template2.doc Page 2 of 30 09/27/20 f Software Requirements Specifications Document 1. Introduction The following subsections of the Software Requirements Specifications (SRS) document should provide an overview of the entire SRS. The thing to keep in mind as you write this document is that you are telling what the system must do – so that designers can ultimately build it. Do not use this document for design!!! 1.1 Purpose Identify the purpose of this SRS and its intended audience. In this subsection, describe the purpose of the particular SRS and specify the intended audience for the SRS. 1.2 Scope In this subsection: (1) Identify the software product(s) to be produced by name (2) Explain what the software product(s) will, and, if necessary, will not do (3) Describe the application of the software being specified, including relevant benefits, objectives, and goals (4) Be consistent with similar statements in higher-level specifications if they exist This should be an executive-level summary. Do not enumerate the whole requirements list here. 1.3 Definitions, Acronyms, and Abbreviations. Provide the definitions of all terms, acronyms, and abbreviations required to properly interpret the SRS. This information may be provided by reference to one or more appendices in the SRS or by reference to documents. This information may be provided by reference to an Appendix. 1.4 References In this subsection: (1) Provide a complete list of all documents referenced elsewhere in the SRS (2) Identify each document by title, report number (if applicable), date, and publishing organization (3) Specify the sources from which the references can be obtained. This information can be provided by reference to an appendix or to another document. If your application uses specific protocols or RFC’s, then reference them here so designers know where to find them. /app/work/qhbc04-srs_template2.doc Page 5 of 30 09/27/20 f Software Requirements Specifications Document 1.5 Overview In this subsection: (1) Describe what the rest of the SRS contains (2) Explain how the SRS is organized Don’t rehash the table of contents here. Point people to the parts of the document they are most concerned with. Customers/potential users care about section 2, developers care about section 3. 2. The Overall Description Describe the general factors that affect the product and its requirements. This section does not state specific requirements. Instead, it provides a background for those requirements, which are defined in section 3, and makes them easier to understand. In a sense, this section tells the requirements in plain English for the consumption of the customer. Section3 will contain a specification written for the developers. 2.1 Product Perspective Put the product into perspective with other related products. If the product is independent and totally self-contained, it should be so stated here. If the SRS defines a product that is a component of a larger system, as frequently occurs, then this subsection relates the requirements of the larger system to functionality of the software and identifies interfaces between that system and the software. If you are building a real system,compare its similarity and differences to other systems in the marketplace. If you are doing a research-oriented project, what related research compares to the system you are planning to build. A block diagram showing the major components of the larger system, interconnections, and external interfaces can be helpful. This is not a design or architecture picture. It is more to provide context, especially if your system will interact with external actors. The system you are building should be shown as a black box. Let the design document present the internals. The following subsections describe how the software operates inside various constraints. 2.1.1 System Interfaces List each system interface and identify the functionality of the software to accomplish the system requirement and the interface description to match the system. These are external systems that you have to interact with. For instance, if you are building a business /app/work/qhbc04-srs_template2.doc Page 6 of 30 09/27/20 f Software Requirements Specifications Document application that interfaces with the existing employee payroll system, what is the API to that system that designer’s will need to use? 2.1.2 Interfaces Specify: (1) The logical characteristics of each interface between the software product and its users. (2) All the aspects of optimizing the interface with the person who must use the system This is a description of how the system will interact with its users. Is there a GUI, a command line or some other type of interface? Are there special interface requirements? If you are designing for the general student population for instance, what is the impact of ADA (American with Disabilities Act) on your interface? 2.1.3 Hardware Interfaces Specify the logical characteristics of each interface between the software product and the hardware components of the system. This includes configuration characteristics. It also covers such matters as what devices are to be supported, how they are to be supported and protocols. This is not a description of hardware requirements in the sense that “This program must run on a Mac with 64M of RAM”. This section is for detailing the actual hardware devices your application will interact with and control. For instance, if you are controlling X10 type home devices, what is the interface to those devices? Designers should be able to look at this and know what hardware they need to worry about in the design. Many business type applications will have no hardware interfaces. If none, just state “The system has no hardware interface requirements” If you just delete sections that are not applicable, then readers do not know if: a. this does not apply or b. you forgot to include the section in the first place. 2.1.4 Software Interfaces Specify the use of other required software products and interfaces with other application systems. For each required software product, include: (1) Name (2) Mnemonic (3) Specification number (4) Version number (5) Source For each interface, provide: (1) Discussion of the purpose of the interfacing software as related to this software product (2) Definition of the interface in terms of message content and format /app/work/qhbc04-srs_template2.doc Page 7 of 30 09/27/20 f Software Requirements Specifications Document What is it about your potential user base that will impact the design? Their experience and comfort with technology will drive UI design. Other characteristics might actually influence internal design of the system. 2.4 Constraints Provide a general description of any other items that will limit the developer's options. These can include: (1) Regulatory policies (2) Hardware limitations (for example, signal timing requirements) (3) Interface to other applications (4) Parallel operation (5) Audit functions (6) Control functions (7) Higher-order language requirements (8) Signal handshake protocols (for example, XON-XOFF, ACK-NACK) (9) Reliability requirements (10) Criticality of the application (11) Safety and security considerations This section captures non-functional requirements in the customers language. A more formal presentation of these will occur in section 3. 2.5 Assumptions and Dependencies List each of the factors that affect the requirements stated in the SRS. These factors are not design constraints on the software but are, rather, any changes to them that can affect the requirements in the SRS. For example, an assumption might be that a specific operating system would be available on the hardware designated for the software product. If, in fact, the operating system were not available, the SRS would then have to change accordingly. This section is catch-all for everything else that might influence the design of the system and that did not fit in any of the categories above. 2.6 Apportioning of Requirements. Identify requirements that may be delayed until future versions of the system. After you look at the project plan and hours available, you may realize that you just cannot get everything done. This section divides the requirements into different sections for development and delivery. Remember to check with the customer – they should prioritize the requirements and decide what does and does not get done. This can also be useful if you are using an iterative life cycle model to specify which requirements will map to which interation. /app/work/qhbc04-srs_template2.doc Page 10 of 30 09/27/20 f Software Requirements Specifications Document 3. Specific Requirements This section contains all the software requirements at a level of detail sufficient to enable designers to design a system to satisfy those requirements, and testers to test that the system satisfies those requirements. Throughout this section, every stated requirement should be externally perceivable by users, operators, or other external systems. These requirements should include at a minimum a description of every input (stimulus) into the system, every output (response) from the system and all functions performed by the system in response to an input or in support of an output. The following principles apply: (1) Specific requirements should be stated with all the characteristics of a good SRS  correct  unambiguous  complete  consistent  ranked for importance and/or stability  verifiable  modifiable  traceable (2) Specific requirements should be cross-referenced to earlier documents that relate (3) All requirements should be uniquely identifiable (usually via numbering like 3.1.2.3) (4) Careful attention should be given to organizing the requirements to maximize readability (Several alternative organizations are given at end of document) Before examining specific ways of organizing the requirements it is helpful to understand the various items that comprise requirements as described in the following subclasses. This section reiterates section 2, but is for developers not the customer. The customer buys in with section 2, the designers use section 3 to design and build the actual application. Remember this is not design. Do not require specific software packages, etc unless the customer specifically requires them. Avoid over-constraining your design. Use proper terminology: The system shall… A required, must have feature The system should… A desired feature, but may be deferred til later The system may… An optional, nice-to-have feature that may never make it to implementation. Each requirement should be uniquely identified for traceability. Usually, they are numbered 3.1, 3.1.1, 3.1.2.1 etc. Each requirement should also be testable. Avoid imprecise statements like, “The system shall be easy to use” Well no kidding, what does that mean? Avoid “motherhood and apple pie” type statements, “The system shall be developed using good software engineering practice” Avoid examples, This is a specification, a designer should be able to read this spec and build the system without bothering the customer again. Don’t say things like, “The /app/work/qhbc04-srs_template2.doc Page 11 of 30 09/27/20 f Software Requirements Specifications Document system shall accept configuration information such as name and address.” The designer doesn’t know if that is the only two data elements or if there are 200. List every piece of information that is required so the designers can build the right UI and data tables. 3.1 External Interfaces This contains a detailed description of all inputs into and outputs from the software system. It complements the interface descriptions in section 2 but does not repeat information there. Remember section 2 presents information oriented to the customer/user while section 3 is oriented to the developer. It contains both content and format as follows:  Name of item  Description of purpose  Source of input or destination of output  Valid range, accuracy and/or tolerance  Units of measure  Timing  Relationships to other inputs/outputs  Screen formats/organization  Window formats/organization  Data formats  Command formats  End messages 3.2 Functions Functional requirements define the fundamental actions that must take place in the software in accepting and processing the inputs and in processing and generating the outputs. These are generally listed as “shall” statements starting with "The system shall… These include:  Validity checks on the inputs  Exact sequence of operations  Responses to abnormal situation, including  Overflow  Communication facilities  Error handling and recovery  Effect of parameters  Relationship of outputs to inputs, including  Input/Output sequences /app/work/qhbc04-srs_template2.doc Page 12 of 30 09/27/20 f Software Requirements Specifications Document Specify the factors required to guarantee a defined availability level for the entire system such as checkpoint, recovery, and restart. This is somewhat related to reliability. Some systems run only infrequently on-demand (like MS Word). Some systems have to run 24/7 (like an e-commerce web site). The required availability will greatly impact the design. What are the requirements for system recovery from a failure? “The system shall allow users to restart the application after failure with the loss of at most 12 characters of input”. 3.6.3 Security Specify the factors that would protect the software from accidental or malicious access, use, modification, destruction, or disclosure. Specific requirements in this area could include the need to:  Utilize certain cryptographic techniques  Keep specific log or history data sets  Assign certain functions to different modules  Restrict communications between some areas of the program  Check data integrity for critical variables 3.6.4 Maintainability Specify attributes of software that relate to the ease of maintenance of the software itself. There may be some requirement for certain modularity, interfaces, complexity, etc. Requirements should not be placed here just because they are thought to be good design practices. If someone else will maintain the system 3.6.5 Portability Specify attributes of software that relate to the ease of porting the software to other host machines and/or operating systems. This may include:  Percentage of components with host-dependent code  Percentage of code that is host dependent  Use of a proven portable language  Use of a particular compiler or language subset  Use of a particular operating system Once the relevant characteristics are selected, a subsection should be written for each, explaining the rationale for including this characteristic and how it will be tested and measured. A chart like this might be used to identify the key characteristics (rating them High or Medium), then identifying which are preferred when trading off design or implementation decisions (with the ID of the preferred one indicated in the chart to the right). The chart below is optional (it can be confusing) and is for demonstrating /app/work/qhbc04-srs_template2.doc Page 15 of 30 09/27/20 f Software Requirements Specifications Document tradeoff analysis between different non-functional requirements. H/M/L is the relative priority of that non-functional requirement. ID Characteristic H/M/L 1 2 3 4 5 6 7 8 9 10 11 12 1 Correctness 2 Efficiency 3 Flexibility 4 Integrity/Security 5 Interoperability 6 Maintainability 7 Portability 8 Reliability 9 Reusability 10 Testability 11 Usability 12 Availability Definitions of the quality characteristics not defined in the paragraphs above follow. • Correctness - extent to which program satisfies specifications, fulfills user’s mission objectives • Efficiency - amount of computing resources and code required to perform function • Flexibility - effort needed to modify operational program • Interoperability - effort needed to couple one system with another • Reliability - extent to which program performs with required precision • Reusability - extent to which it can be reused in another application • Testability - effort needed to test to ensure performs as intended • Usability - effort required to learn, operate, prepare input, and interpret output THE FOLLOWING (3.7) is not really a section, it is talking about how to organize requirements you write in section 3.2. At the end of this template there are a bunch of alternative organizations for section 3.2. Choose the ONE best for the system you are writing the requirements for. 3.7 Organizing the Specific Requirements For anything but trivial systems the detailed requirements tend to be extensive. For this reason, it is recommended that careful consideration be given to organizing these in a manner optimal for understanding. There is no one optimal organization for all systems. Different classes of systems lend themselves to different organizations of requirements in section 3. Some of these organizations are described in the following subclasses. 3.7.1 System Mode /app/work/qhbc04-srs_template2.doc Page 16 of 30 09/27/20 f Software Requirements Specifications Document Some systems behave quite differently depending on the mode of operation. When organizing by mode there are two possible outlines. The choice depends on whether interfaces and performance are dependent on mode. 3.7.2 User Class Some systems provide different sets of functions to different classes of users. 3.7.3 Objects Objects are real-world entities that have a counterpart within the system. Associated with each object is a set of attributes and functions. These functions are also called services, methods, or processes. Note that sets of objects may share attributes and services. These are grouped together as classes. 3.7.4 Feature A feature is an externally desired service by the system that may require a sequence of inputs to effect the desired result. Each feature is generally described in as sequence eof stimulus-response pairs. 3.7.5 Stimulus Some systems can be best organized by describing their functions in terms of stimuli. 3. 7.6 Response Some systems can be best organized by describing their functions in support of the generation of a response. 3.7.7 Functional Hierarchy When none of he above organizational schemes prove helpful, the overall functionality can be organized into a hierarchy of functions organized by either common inputs, common outputs, or common internal data access. Data flow diagrams and data dictionaries can be use dot show the relationships between and among the functions and data. 3.8 Additional Comments /app/work/qhbc04-srs_template2.doc Page 17 of 30 09/27/20 f Software Requirements Specifications Document Outline for SRS Section 3 Organized by mode: Version 1 3. Specific Requirements 3.1 External interface requirements 3.1.1 User interfaces 3.1.2 Hardware interfaces 3.1.3 Software interfaces 3.1.4 Communications interfaces 3.2 Functional requirements 3.2.1 Mode 1 3.2.1.1 Functional requirement 1.1 ..... 3.2.1.n Functional requirement 1.n 3.2.2 Mode 2 ..... 3.2.m Mode m 3.2.m.1 Functional requirement m.1 ..... 3.2.m.n Functional requirement m.n 3.3 Performance Requirements 3.4 Design Constraints 3.5 Software system attributes 3.6 Other requirements /app/work/qhbc04-srs_template2.doc Page 20 of 30 09/27/20 f Software Requirements Specifications Document Outline for SRS Section 3 Organized by mode: Version 2 3. Specific Requirements 3.1 Functional Requirements 3.1.1 Mode 1 3.1.1.1 External interfaces 3.1.1.1 User interfaces 3.1.1.2 Hardware interfaces 3.1.1.3 Software interfaces 3.1.1.4 Communications interfaces 3.1.1.2 Functional Requirement 3.1.1.2.1 Functional requirement 1 ..... 3.1.1.2.n Functional requirement n 3.1.1.3 Performance 3.1.2 Mode 2 ..... 3.1.m Mode m 3.2 Design constraints 3.3 Software system attributes 3.4 Other requirements /app/work/qhbc04-srs_template2.doc Page 21 of 30 09/27/20 f Software Requirements Specifications Document Outline for SRS Section 3 Organized by user class (i.e. different types of users ->System Adminstrators, Managers, Clerks, etc.) 3. Specific Requirements 3.1 External interface requirements 3.1.1 User interfaces 3.1.2 Hardware interfaces 3.1.3 Software interfaces 3.1.4 Communications interfaces 3.2 Functional requirements 3.2.1 User class 1 3.2.1.1 Functional requirement 1.1 ..... 3.2.1.n Functional requirement 1.n 3.2.2 User class 2 ..... 3.2.m User class m 3.2.m.1 Functional requirement m.1 ..... 3.2.m.n Functional requirement m.n 3.3 Performance Requirements 3.4 Design Constraints 3.5 Software system attributes 3.6 Other requirements /app/work/qhbc04-srs_template2.doc Page 22 of 30 09/27/20 f Software Requirements Specifications Document Outline for SRS Section 3 Organized by stimulus (Good for event driven systems where the events form logical groupings) 3 Specific Requirements 3.1 External interface requirements 3.1.1 User interfaces 3.1.2 Hardware interfaces 3.1.3 Software interfaces 3.1.4 Communications interfaces 3.2 Functional requirements 3.2.1 Stimulus 1 3.2.1.1 Functional requirement 1.1 ..... 3.2.1.n Functional requirement 1.n 3.2.2 Stimulus 2 ..... 3.2.m Stimulus m 3.2.m.1 Functional requirement m.1 ..... 3.2.m.n Functional requirement m.n 3.3 Performance Requirements 3.4 Design Constraints 3.5 Software system attributes 3.6 Other requirements /app/work/qhbc04-srs_template2.doc Page 25 of 30 09/27/20 f Software Requirements Specifications Document Outline for SRS Section 3 Organized by response (Good for event driven systems where the responses form logical groupings) 3 Specific Requirements 3.1 External interface requirements 3.1.1 User interfaces 3.1.2 Hardware interfaces 3.1.3 Software interfaces 3.1.4 Communications interfaces 3.2 Functional requirements 3.2.1 Response 1 3.2.1.1 Functional requirement 1.1 ..... 3.2.1.n Functional requirement 1.n 3.2.2 Response 2 ..... 3.2.m Response m 3.2.m.1 Functional requirement m.1 ..... 3.2.m.n Functional requirement m.n 3.3 Performance Requirements 3.4 Design Constraints 3.5 Software system attributes 3.6 Other requirements /app/work/qhbc04-srs_template2.doc Page 26 of 30 09/27/20 f Software Requirements Specifications Document Outline for SRS Section 3 Organized by functional hierarchy (Good if you have done structured analysis as part of your design.) 3 Specific Requirements 3.1 External interface requirements 3.1.1 User interfaces 3.1.2 Hardware interfaces 3.1.3 Software interfaces 3.1.4 Communications interfaces 3.2 Functional requirements 3.2.1 Information flows 3.2.1.1 Data flow diagram 1 3.2.1.1.1 Data entities 3.2.1.1.2 Pertinent processes 3.2.1.1.3 Topology 3.2.1.2 Data flow diagram 2 3.2.1.2.1 Data entities 3.2.1.2.2 Pertinent processes 3.2.1.2.3 Topology ..... 3.2.1.n Data flow diagram n 3.2.1.n.1 Data entities 3.2.1.n.2 Pertinent processes 3.2.1.n.3 Topology 3.2.2 Process descriptions 3.2.2.1 Process 1 3.2.2.1.1 Input data entities 3.2.2.1.2 Algorithm or formula of process 3.2.2.1.3 Affected data entities 3.2.2.2 Process 2 3.2.2.2.1 Input data entities 3.2.2.2.2 Algorithm or formula of process 3.2.2.2.3 Affected data entities .…. 3.2.2.m Process m 3.2.2.m.1 Input data entities 3.2.2.m.2 Algorithm or formula of process 3.2.2.m.3 Affected data entities 3.2.3 Data construct specifications 3.2.3.1 Construct 1 3.2.3.1.1 Record type 3.2.3.1.2 Constituent fields 3.2.3.2 Construct 2 3.2.3.2.1 Record type /app/work/qhbc04-srs_template2.doc Page 27 of 30 09/27/20 f