1. Definition
Requirements engineering, refers to the use of engineering methods and standards to collect, record and analyze the customer's needs for information technology, and ultimately determine the functions that need to be achieved by the system, as well as the relevant features and constraints of the function. Requirements engineering contains three main parts: requirements research, requirements analysis, requirements management.
Note: About requirements management
Requirements management is a very important part of requirements engineering, including requirements tracking, control, change, version management, etc., it is to ensure that the content of the system, the quality of the progress of the important means of requirements management is more in favor of the software process management.
2. Role
The role of requirements engineering is summarized in one sentence: to collect what customers want to do, and ultimately determine what to actually do.
For the development of an application, the quality of the results of requirements engineering greatly affects the design of the software results, is the main link in determining the success or failure, from the customer to obtain a complete, record, analyze and confirm the requirements, and correctly passed to the subsequent project is a requirement analysts must have the ability. Requirements engineering analysis results in the formation of the requirements specification is not only the subsequent design and development of the basis, but also the customer to complete the system evaluation, acceptance of the basis.
On the other hand, the content of requirements engineering also greatly affects the cost of software development, technology, cycle time, resources, quality, and end customer satisfaction and many other aspects. The results of requirements engineering not only affect the final results obtained by the customer, but also affect the ultimate interests of the software developer.
The core work of requirements engineering is requirements research and requirements analysis, and there are two main final deliverables.
1) Requirements research results (requirements research data summary)
From the customer site through face-to-face research to collect first-hand demand information, including graphics, text and tables and other ways to record the original data, the formation of requirements research data summary.
2) Requirements analysis results (requirements specification)
Based on the analysis of the aforementioned research data, identify the final need to develop all the content, and confirmed by the customer, and ultimately the formation of the requirements specification, which is the basis for the subsequent design and development process.
1. Requirements collection and validation
In the process of going from the unclear original requirements of the customer to the process of coding and development, the part that contributes the most to the convergence is the ② requirements engineering, and the part that is easier to normalize and standardize is the part of the ③-5. ② The complexity of ① is sorted out and formed into a clear requirement specification. ③The results of ② are further extracted and transformed into the design results of architecture, functions and data. The results of ③ are further extracted and converted into the composition of components and mechanisms. ⑤ Develop the final software by coding the results of ④.
It can be seen from the graphical advancement changes, requirements engineering ② is responsible for the original requirements ① and the formation of a clear, clear, can be confirmed requirements specification task; and ③ ~ ⑤ a series of work, the more after the part of the more simple, the lower the complexity of the reduction of the lower, the more convergence of the things to be done. ② Requirements engineering is the pioneer, which takes on the most miscellaneous, messy and tiring work, and plays the biggest role in convergence in the five steps from the original customer requirements to coding. ② part of the graph of the convergence of the larger (trapezoidal slope), ③ later design and development of the graph of the closer to the positive rectangle, the smoother the work, otherwise ② ～ ⑤ are large slope of the trapezoidal shows that the requirements of the engineering work is not in place, in the subsequent design and development of the previous design and development will continue to find that there are problems in the previous requirements resulting in rework.
Note: The meaning of "convergence"
Convergence refers to the process of bringing complex original requirements together into a standardized operation. Standardized job content is not affected by the demand, regardless of whether the demand is complex or not the content is fixed.
2. Requirements, not always from customer research
Are the requirements for building an information system always obtained from the customer? This question reflects how much of the completed system has been proposed by software engineers (including consulting, requirements, design, development, implementation, etc.) These proposals often contain more advanced requirements, more added value, and multiple sources of requirements.
1) basic needs
Basic needs from the customer "research", this type of demand is mainly functional requirements, basically according to the customer's wishes to design and development, most of the content in the demand research, requirements analysis phase to determine.
2) Intermediate requirements
Intermediate requirements are not the functional requirements directly from the customer, but in the requirements analysis phase, business design phase, through the conversion of the business needs of the customer to the business requirements, optimization, fill in the gaps, enhance the process of demand, that is, to improve the business needs.
3) Advanced Requirements
Advanced requirements mainly come from software engineers based on the customer's target needs, new design concepts, new technologies and so on, that is to say, advanced requirements are designed by software engineers, for example, "things to find people process design (architecture)" "Component design (functionality) according to the task" "Reuse of data (data)" and so on. "Designing requirements requires that software engineers have sufficient knowledge and skills.
The order of difficulty in acquiring the above three sources of requirements is Advanced Requirements > Intermediate Requirements > Basic Requirements.
Software engineers need to realize that the requirements engineering (research and analysis) is completed, not all the work to obtain the requirements is completed, but only by the customer directly to the completion of the requirements, and through the design engineering requirements discovery has not yet started.
Note: Advanced requirements affect development costs here only consider how to uncover valuable requirements, not the development costs associated with new requirements.
Requirements are usually categorized into two broad groups: functional and non-functional.
Functional requirements are the business processing functions that a system must provide, and are the main body of software requirements. When a requirement is not preceded by an adjective, it is usually referred to as a functional requirement.
Acquisition requirements can be divided into three categories, there is a conversion relationship between them, in accordance with the order of conversion is divided into: target requirements, business requirements and functional requirements.
Target requirements: the customer's information technology goals, ideas, hopes, values.
Business requirements: the system proposed by the customer to correspond to the content of the business, process, rules, etc.
Functional requirements.
Functional requirements: to determine the system must provide to deal with the business needs of the function and the specific description of the function.
Non-functional requirements refers to the establishment of a number of indicative conditions to determine the operation of the system, rather than for a specific functional requirements for business processing, they are used to determine whether the system can meet the following conditions: security, reliability, interoperability, robustness, ease of use, maintainability, portability, reusability, expandability, etc..
The results of pre-sales consulting contains a lot of demand analysis, business design is very important inputs, especially a lot of "target demand" from this, the target demand for subsequent information systems overall planning, top-level design has a very important impact
1. pre-sales consulting content
In the stage before entering into the design project, all exchanges and communication with customers are aimed at obtaining the demand, especially for large-scale projects, before the signing of the contract there is usually a pre-sales consulting stage, in this stage of the general software vendors will be sent to the more experienced consultants (such as expert consultants) to communicate with the customer to explore what kind of customer needs can be based on the needs provided solutions, this stage of the consultation has the following characteristics.● The contract has not yet been signed, the specific information system to do what is not yet determined, whether the contract depends on the results of the consultation.
● At this time, the customer side of the participants are mostly high-level enterprise, such as operators, senior managers and information technology executives.
● The customer's needs are mostly target needs, business needs, and even difficult pain points, and less about functional needs.
● Requirements will be related to the development strategy of the enterprise, the existing major problems and the company's expectations of information technology.
● The content of the exchange may be more abstract, and the demand is mostly implicit, whether it can become a real demand for the consultant to guide, identify, confirm and so on. Pre-sales consulting is usually about the relatively high-end needs, they are the main source of the subsequent demand analysis "target demand", is the business managers on the value of the information system expectations (although it may be implicitly put forward), in the follow-up of the so-called "requirements research "stage, often may not have the opportunity to go directly to listen to the needs of business executives, so this part of the content to be recorded as a very important demand, as a follow-up to the demand for analysis of the important reference material.
2. Pre-sales consulting and demand engineering
The pre-sales consulting approach is very dependent on the consultant's personal ability and charisma, it is not particularly standardized and standard deliverables as well as templates, so there is no consulting work explicitly included in the demand engineering (software vendors may be divided into different methods), which are focused on different.
(1) pre-sales consulting: the focus is on pre-sales consulting activities, proposed solutions to assist the sales department to sign the contract.
(2) demand engineering: the focus is to enter the customer site, the contract has been determined to carry out detailed research. Although the main purpose of the consultation is to facilitate the signing of the contract, but the information collected during the consultation phase is very important to analyze the object of demand engineering, especially the "target demand".
3. The role of the consultant
(1) The consultant, on behalf of the software company's highest level of professionalism, he should be the business card of the software vendor.
(2) The consultant is a comprehensive explanation of the concept of software vendors and the proposition of the evangelist.
(3) The consultant establishes a high starting point, the whole project starts from a high point, the total value will be high (for both the software vendor and the customer).
(4) The consultant should be able to use the knowledge and experience of the reserves, for the customer's decision makers to act as advisers, counselors.
(5) The focus of the consultant's work is to communicate with the decision makers of the customer's project, to obtain the customer's objectives, expectations and other target needs.
4. The ability of the consultant requirements
For expert consultants engaged in pre-sales consulting, his requirements are higher, mainly in the following areas (not limited to).
1) communication ability to communicate with the object of the customer's decision-making, production, finance and other intermediate management, the ability to higher requirements, for example,
● Understanding: whether to be able to understand the gist of high-level conversations, the implied demand?
● Demonstration: can you adequately demonstrate the service and product capabilities of the software company?
● Convince: can convince customers, for example, after the introduction of the system to make corresponding changes in the organization or management system?
This is the first time that we have seen a software company that has been able to convince its customers that it is a good idea to use the software.
2) Professional competence for the consultant, his professional competence requirements are comprehensive.
● Is the mastery of the basic knowledge of industry consulting?
● Is familiar with the client's main business and auxiliary business knowledge?
● Whether you are basically clear about the latest technology, matching cases, solutions, etc. in the software industry.
The engineering decomposition of requirements engineering is divided into two phases, namely, the requirements research phase and the requirements analysis phase
There are two main tasks in the requirements research phase: requirements research, and data summarization.
(1) Requirements research: the use of questionnaires, the status quo composition map, interview records, existing forms to collect customer needs.
(2) data summary: the information collected during the research process is summarized to form a summary of demand research data, as the basis for analysis in the demand analysis stage.
There are two main tasks in the demand analysis phase: demand analysis, data summary.
(1) Requirements analysis: Based on the requirements of the research data to analyze the needs of customers, and ultimately confirm the system needs to achieve the function.
(2) data summary: the results of the analysis of the information is summarized to form a requirements specification, as the subsequent input to the various design stages.
1. Demand research
The purpose is to collect and record customer demand for information technology, focusing on the content of the "record", rather than "analysis" or "design".
2. Demand analysis
On the basis of the understanding of the demand for research information, extraction, categorization, sorting, and at the same time, according to the analysis of the research to make up for the breakpoints, and the use of a more standardized way of expression, it is important to note that: the demand analysts through the analysis of the target needs, business needs and other high-end needs to add a personal understanding, as well as the enhancement of the company's information technology, so the demand analysis is a valuable opinion. Valuable opinions, so the results of the requirements analysis and the original record will be different between the requirements analyst's understanding on behalf of the software development team's understanding, and as a basis for confirmation to the customer, the final draft formed the next design session of the input information.
Therefore, the ability of the requirements analyst will ultimately affect the content, technology, cost and cycle time of the information system.
3. The relationship between the two
Both are described in non-technical design terms, with requirements research documented in "customer terms" and requirements analysis expressed in "business design terms". In the purpose of the work of the two are different, for example: requirements analysis to do business process diagrams must have business integrity, and in line with the standard expression of business processes; while the requirements of the business process diagrams collected by the research may be fragments of the discontinuous running account. Requirements analysis of the content of the demand entity to extract, categorization, the establishment of the demand system table; demand research stage does not require this comb, only the original collection and record can be (to retain the original state). The role of the results of the demand analysis are two: the front-end customer confirmation, to the back-end output design basis; the results of the demand research is only to provide information to the demand analysis. The biggest difference between the two is as follows.
(1) Requirements research: focus on the collection of raw requirements, records.
(2) Requirements analysis: focus on the overall understanding, collection, confirmation, requirements analysis is not a repeat of the requirements research.
The impact of the information completed in the requirements engineering phase on the subsequent design phases
(1) Requirements research: collecting and sorting out the customer's original requirements.
(2) Requirements analysis: research information is only provided to the requirements analysis, can not be directly referenced by the design (can be referred to).
(3) outline design: to complete the results of the needs analysis of the full coverage, give planning.
(4) Detailed design: in principle, the results of the outline design of the detailed design.
(5) application design: the requirements of the needs analysis on the application of the requirements of the system to give the realization of the method.
(6) technical design: non-functional requirements in the results of the requirements analysis, technical requirements to respond.
(7), (8) development ~ test: can not be the results of requirements analysis as the basis for development and testing (can be referred to).
(X) System Acceptance: The final acceptance of the system by the customer is based on the requirements specification.?
Requirements research is not in accordance with the order of work or the relationship between the content of the research to carry out, so there is no strict decomposition of work, it is in accordance with the needs of the different forms of expression of different division of the form of expression of the needs of the form is divided into three types.
(1) Graphics: including graphics that express the current state of the customer's business, the needs expressed in the interface.
(2) Textual: the needs expressed in text collected through questionnaires and interviews.
(3) Forms: the actual reports provided by the customer, the demand for the form of documents.
These three types of information are not necessarily related to each other or order, can be collected at the same time.
The results of the needs research after sorting, the separation of non-functional requirements after the rest are functional requirements, according to the definition of functional requirements can be divided into: target requirements, business requirements and functional requirements, there is a conversion relationship between the three target requirements → business requirements → functional requirements. Strictly speaking, they are not three types of requirements but three levels of requirements, and ultimately only the third level of functional requirements can be realized in the system. The decomposition of work in the analysis phase is determined in this order.
(1) The first level of work: the analysis of the target requirements, the conversion to business requirements.
(2) The second level of work: the analysis of business requirements, the conversion to functional requirements.
(3) The third layer of work: the analysis and determination of functional requirements.
The establishment of the corresponding demand system, without this demand system, is to solve the customer's problem with personal experience, with this system, you can do with the collective experience and wisdom to solve the customer's problem. Here the demand system mainly refers to the establishment of "business needs".
The establishment of the demand system can bring a lot of value, try a few examples.
1. Systematic accumulation of knowledge
(1) The results of research and practice can be organized to accumulate, including: concepts, methods, standards, norms and so on.
(2) The accumulation of customer value, including: different business areas, industries, segments, systems, modules, functions, etc..
2. The need for commercial scale
(1) Enhance the value of the software enterprise can provide customers with systematic solutions.
(2) Extract, plan, and establish new business models to respond quickly to customer needs.
3. Reduce costs and improve efficiency
(1) Accumulated knowledge can be effectively reused, **** enjoy, reduce costs.
(2) can significantly shorten the development cycle, while helping to reduce the "demand distortion" phenomenon.
4. The first step in risk avoidance
(1) The best way to avoid risk is for everyone to know how to do it beforehand, which can be done with system support.
(2) the lack of human capacity, research and analysis of the short time problem, you can use the knowledge base to help solve.
5. A shortcut to quickly develop talent as a demand analyst, is required to have a lot of ability, such as "business ability", "communication ability", "abstraction ability", "performance ability", "ability to communicate", "ability to communicate", "ability to communicate", "ability to communicate", "ability to communicate", "ability to communicate", "ability to communicate". "But this is too abstract, difficult to understand, and can't be accomplished in a day. The establishment of a knowledge base that can provide most people with direct reference and **** to enjoy, so that those who need to be "in order to follow", it is like a "business platform", can let everyone provide experience, share knowledge, and by everyone **** with the maintenance.
Requirements engineering can be said to be the basics for everyone involved in the software industry. This is because it centers on:
(1) How to communicate with others, how to quickly understand others' ideas, how to convey ideas to others, etc.?
(2) How do you quickly find an entry point to a complex, unfamiliar object of study?
(3) How to express an unclear object in simple language, graphs or tables?
(4) How to translate the needs expressed in customer terms (knowledge, experience) into business design terms? And so on.
? The number of management information system requirements, the demand for value-added high and low, depending on the customer's purpose of information technology and the ability of demand analysts, demand analysts are usually sandwiched between the front of the "consultant" and the back of the "business designers" when the Software companies have these two positions or the project configuration of these two positions, the demand analyst's own ability to project the impact can be controlled to some extent, if the software companies do not have the other two positions or the project is not configured for these two positions, then the demand analyst to determine the highest level of the project (the highest level of the enterprise management project is usually determined by the business designer), so he must have a certain level of knowledge. Therefore, he must have some knowledge of consulting and business design.
Requirements engineering, with design inputs as the required standard
Requirements engineering is not only a "knowledge", but also a "technology" that can be implemented qualitatively and quantitatively, with templates, processes, and standards, and more importantly, with a strict transfer to the subsequent design. It has a template, process, standards, and more importantly, it has a strict transfer and inheritance relationship with the subsequent design, due to the scope of the design, content, format, etc. as the output standard of the demand engineering, so the content of the demand engineering to be done is very specific, standardized, as a "technology" of the demand engineering operability is greatly enhanced. Establishing a methodology that uses design input as the standard for requirements engineering can improve design quality, product quality, and work efficiency.