Software Projects

Software Projects • You need to deliver the following things: • Project Agreement (already completed) • Documentation • Code • Demonstration for Client • Presentation in Class CS410 – Software Engineering Lecture #18: Rationale Management

Software Projects • Documentation: • Describes the capabilities of the software product • Explains to the end user how to use the software • Describes to other developers the most important classes, their members and methods. • Due by May 14. • It is recommended to write at least a rough draft of the documentation before writing the code. CS410 – Software Engineering Lecture #18: Rationale Management

Software Projects • Code: • Programming language: C++ • Operating system: Linux (software must be demonstrated on campus) • Object-oriented design • Comments • Due by May 14 (e-mail) CS410 – Software Engineering Lecture #18: Rationale Management

Software Projects • Demonstration for Client: • Demonstration in Unix Lab, PC Lab, Visual Attention Lab or client’s office • Can be done on a team member’s laptop • Customer will play around with the software and try to crash it • Code review: Every project participant will be asked questions about her/his code and why she/he chose that particular implementation. • Due by May 14 CS410 – Software Engineering Lecture #18: Rationale Management

Software Projects • Presentation in Class: • Duration for each team’s presentation: 20 minutes • Every team member has to speak • One person (team leader) provides overview of the system • Others present their part of the system, algorithms and data structures they used, issues they encountered, how they were resolved, etc. • Will take place on May 1, 6, and 8. CS410 – Software Engineering Lecture #18: Rationale Management

Software Projects • Rules: • Each team member must implement a clearly defined part of the software. • No re-use of any code unless explicitly allowed by the customer. • It is recommended to schedule at least one meeting with the customer during the development process. • Team members will evaluate each other after project completion. CS410 – Software Engineering Lecture #18: Rationale Management

Rationale Management • Rationale: • What is it? • Why should you care? • Rationale methods: • Representing rationale • Authoring rationale • Accessing rationale • State of practice & research • Summary CS410 – Software Engineering Lecture #18: Rationale Management

An Aircraft Example • A320: • First fly-by-wire passenger aircraft • 150 seats, short to medium haul • A319 & A321: • Derivatives of A320 • Same handling as A320 • Rationale: • Reduce pilot training & maintenance costs • Increase flexibility for airline CS410 – Software Engineering Lecture #18: Rationale Management

An Aircraft Example • A330 & A340: • Long haul and ultra long haul • 2x seats, 3x range • Similar handling as A320 family • Rationale: • With minimum cross training, A320 pilots can be certified to fly A330 and A340 airplanes • Consequence: • Any change in these five airplanes must maintain this similarity CS410 – Software Engineering Lecture #18: Rationale Management

What is Rationale? • Rationale is the reasoning that lead to the system. • Rationale includes: • Issues that were addressed, • Alternatives that were considered, • Decisions that were made to resolve the issues, • Criteria that were used to guide decisions, and • Debate developers went through to reach a decision. CS410 – Software Engineering Lecture #18: Rationale Management

Why Rationale? • Software systems are similar to passenger airplanes: • They result from a large number of decisions taken over an extended period of time. • Evolving assumptions • Legacy decisions • Conflicting criteria • High maintenance cost • Loss & rediscovery of information CS410 – Software Engineering Lecture #18: Rationale Management

Rationale Helps Deal with Change • Improve maintenance support: • Provide maintainers with design context • Improve learning: • New staff can learn the design by replaying the decisions that produced it • Improve analysis and design: • Avoid duplicate evaluation of poor alternatives • Make consistent and explicit trade-off CS410 – Software Engineering Lecture #18: Rationale Management

Levels of Rationale • No rationale captured: • Rationale is only present in memos, online communication, developers’ memory • Rationale reconstruction: • Rationale is documented in a document justifying the final design • Rationale capture: • Rationale is documented during design as it is developed • Rationale integration: • Rationale drives the design CS410 – Software Engineering Lecture #18: Rationale Management

Example: Centralized Traffic Control Trains S2 S3 Track circuits Signals Switches S1 S4 • CTC systems enable dispatchers to monitor and control trains remotely, • CTC allows the planning of routes and re-planning in case of problems. T1291> SW1 SW2 <T1515 CS410 – Software Engineering Lecture #18: Rationale Management

Centralized Traffic Control • CTC systems are ideal examples of rationale capture: • Long lived systems (some systems include relays installed last century) • Extended maintenance life cycle • Downtime is expensive (although not safety critical) • Low tolerance for bugs • Transition to mature technology • Initial developers are not available CS410 – Software Engineering Lecture #18: Rationale Management

Issues display?:Issue input?:Issue • Issues are concrete problems which usually do not have a unique, correct solution. • Issues are phrased as questions. How should track sections be displayed? How should the dispatcher input commands? CS410 – Software Engineering Lecture #18: Rationale Management

Proposals display?:Issue input?:Issue addressed by addressed by addressed by text-based:Proposal point&click:Proposal • Proposals are possible alternatives to issues. • One proposal can be shared across multiple issues. The display used by the dispatcher can be a text only display with graphic characters to represent track segments. The interface for the dispatcher could be realized with a point & click interface. CS410 – Software Engineering Lecture #18: Rationale Management

Consequent Issues display?:Issue input?:Issue addressed by addressed by addressed by text-based:Proposal point&click:Proposal raises terminal?:Issue • Consequent issues are issues raised by the introduction of a proposal. Which terminal emulation should be used for the display? CS410 – Software Engineering Lecture #18: Rationale Management

Criteria display?:Issue input?:Issue addressed by addressed by addressed by meets meets text-based:Proposal point&click:Proposal raises fails fails terminal?:Issue usability$:Criterion availability$:Criterion • A criterion represent a goodness measure. • Criteria are often design goals or nonfunctional requirements. The time to input commands should be less than two seconds. The CTC system should have at least a 99% availability. CS410 – Software Engineering Lecture #18: Rationale Management

Arguments • Arguments represent the debate developers went through to arrive to resolve the issue. • Arguments can support or oppose any other part of the rationale. • Arguments constitute the largest part of the rationale. CS410 – Software Engineering Lecture #18: Rationale Management

Arguments is opposed by display?:Issue input?:Issue addressed by addressed by addressed by meets meets text-based:Proposal point&click:Proposal raises fails fails is supported by terminal?:Issue availability-first!:Argument usability$:Criterion availability$:Criterion Point&click interfaces are more complex to implement than text-based interfaces. Hence, they are also more difficult to test. The point&click interface risks introducing fatal errors in the system that would offset any usability benefit the interface would provide. CS410 – Software Engineering Lecture #18: Rationale Management

Resolutions • Resolutions represent decisions. • A resolution summarizes the selected alternative and the supporting argument. • A resolved issue is said to be closed. • A resolved issue can be re-opened if necessary, in which case the resolution is demoted. CS410 – Software Engineering Lecture #18: Rationale Management

Resolutions text-based&keyboard :Resolution resolves resolves is opposed by display?:Issue input?:Issue addressed by addressed by addressed by meets meets text-based:Proposal point&click:Proposal raises fails fails is supported by terminal?:Issue availability-first!:Argument usability$:Criterion availability$:Criterion CS410 – Software Engineering Lecture #18: Rationale Management

Representing Rationale: Issue Models resolves Resolution. Issue? is a consequence responds meets + Proposal Criterion$ fails - supports + objects to - supports + objects to - Argument! CS410 – Software Engineering Lecture #18: Rationale Management

Representing Rationale • Many issue models have been proposed: • IBIS, QOC, DRL, WinWin • Similar in their essence • Differ in the amount of detail that can be captured • Challenges: • Require tool support for capture and access • Require integration with project management tools • Require integration with methodology CS410 – Software Engineering Lecture #18: Rationale Management

Authoring Rationale • Approaches: • Reconstruction • Record-and-replay • Byproduct of development methodology • Challenges: • Lot of information to capture • Disruptive for developers • Formalizing knowledge is expensive CS410 – Software Engineering Lecture #18: Rationale Management

Accessing Rationale • Browse & search: • Full text search allows to identify interesting nodes • Issue model links allow the browsing of related issues quickly • Passive & active design critique: • Rationale can be used by knowledge based critiques to evaluate a design • Challenges: • Evolving terminology • Navigation through a large flat space CS410 – Software Engineering Lecture #18: Rationale Management

State of the Practice • Standalone issue based tools: • QuestMap • Problem management tools: • Work flow application tracking problems and resolutions • Integrated with configuration management • Some tools (e.g., ClearQuest) allow schema to be customized • RequisitePro: • Requirements management • Integrated with configuration management • Explicitly captures rationale behind change CS410 – Software Engineering Lecture #18: Rationale Management

An example of issue database (LN IBIS database template in Domino Lotus Notes). CS410 – Software Engineering Lecture #18: Rationale Management

State of Research • Many solutions for representation exist and can be tailored to a specific problem. • Progress in natural language search and in hypertext technology make access a less critical issue. • Current challenges: • Integration with methodology • Integration with tools • Overhead CS410 – Software Engineering Lecture #18: Rationale Management

Open Issues • Formalizing knowledge is costly: • Maintaining a consistent design model is expensive. • Capturing and maintaining its rationale is worse. • The benefits of rationale are not perceived by current developers: • If the person who does the work is not the one who benefits from it, the work will have lower priority. • 40-90% of off-the-shelf software projects are terminated before the product ships. • Capturing rationale is usually disruptive. • Current approaches do not scale to real problems. CS410 – Software Engineering Lecture #18: Rationale Management

Why Software Configuration Management? • The problem: • Multiple people have to work on software that is changing • More than one version of the software has to be supported: • Released systems • Custom configured systems (different functionality) • System(s) under development • Software must run on different machines and operating systems Need for coordination • Software Configuration Management • manages evolving software systems • controls the costs involved in making changes to a system CS410 – Software Engineering Lecture #18: Rationale Management

What is Software Configuration Management? • Definition: • A set of management disciplines within the software engineering process to develop a baseline. • Description: • Software Configuration Management encompasses the disciplines and techniques of initiating, evaluating and controlling change to software products during and after the software engineering process. • Standards (approved by ANSI): • IEEE 828: Software Configuration Management Plans • IEEE 1042: Guide to Software Configuration Management CS410 – Software Engineering Lecture #18: Rationale Management

SCM Activities • Configuration item identification • is the modeling of the system as a set of evolving components • Promotion management • is the creation of versions for other developers • Release management • is the creation of versions for the clients and users • Branch management • is the management of concurrent development • Variant management • is the management of versions intended to coexist • Change management • is the handling, approval and tracking of change requests CS410 – Software Engineering Lecture #18: Rationale Management

SCM Roles • Configuration Manager: • Responsible for identifying configuration items. The configuration manager can also be responsible for defining the procedures for creating promotions and releases • Change control board member: • Responsible for approving or rejecting change requests • Developer: • Creates promotions triggered by change requests or the normal activities of development. The developer checks in changes and resolves conflicts • Auditor: • Responsible for the selection and evaluation of promotions for release and for ensuring the consistency and completeness of this release CS410 – Software Engineering Lecture #18: Rationale Management

Terminology and Methodology • What are • Configuration Items, • Baselines, • SCM Directories, • Versions, Revisions and Releases? The usage of the terminology presented here is not strict but varies for different configuration management systems. CS410 – Software Engineering Lecture #18: Rationale Management

Terminology: Configuration Item • “An aggregation of hardware, software, or both, that is designated for configuration management and treated as a single entity in the configuration management process.” Software configuration items are not only program code segments but all type of documents that are produced during development, e.g.: • all types of code files • drivers for tests • analysis or design documents • user or developer manuals • system configurations (e.g. version of compiler used) In some systems, not only software but also hardware configuration items (CPUs, bus speed frequencies) exist! CS410 – Software Engineering Lecture #18: Rationale Management

Terminology: Baseline • “A specification or product that has been formally reviewed and agreed to by responsible management, that thereafter serves as the basis for further development, and can be changed only through formal change control procedures.” • Examples: • Baseline A: The API of a program is completely defined; the bodies of the methods are empty. • Baseline B: All data access methods are implemented and tested; programming of the GUI can start. • Baseline C: GUI is implemented, test-phase can start. CS410 – Software Engineering Lecture #18: Rationale Management

More on Baselines Release (Customer) Version (Developer) Revision (Developer) • Many naming schemes for baselines exist (1.0, 6.01a, ...). • 3 digit scheme: 7.5.5 CS410 – Software Engineering Lecture #18: Rationale Management

Baselines in SCM Baseline A (developmental) All changes relative to baseline A Baseline B (functional) All changes relative to baseline B Baseline C (beta test) All changes relative to baseline C Official Release CS410 – Software Engineering Lecture #18: Rationale Management

Standard SCM Directories Promotion Release • Programmer’s Directory • (IEEE Std: “Dynamic Library”) • Completely under control of one programmer. Master Directory • (IEEE Std: “Controlled Library”) • Central directory of all promotions. Central source code archive Software Repository • (IEEE Std: “Static Library”) • Externally released baselines. Foo’95 Foo’98 CS410 – Software Engineering Lecture #18: Rationale Management

Change Management • Change management is the handling of change requests. • A change request leads to the creation of a new release. • General change process: • The change is requested (this can be done by anyone including users and developers). • The change request is assessed against project goals. • Following the assessment, the change is accepted or rejected. • If it is accepted, the change is assigned to a developer and implemented. • The implemented change is audited. CS410 – Software Engineering Lecture #18: Rationale Management

Change Management • The complexity of the change management process varies with the project: • Small projects can perform change requests informally and fast. • Complex projects require detailed change request forms and the official approval by one or more managers. CS410 – Software Engineering Lecture #18: Rationale Management

Controlling Changes Promote Policy Release Policy User Master Directory Software Repository Programmer Promotion Release • Two types of controlling change: • Promotion: The internal development state of a software is changed. • Release:A set of promotions is distributed outside the development organization. CS410 – Software Engineering Lecture #18: Rationale Management

Change Policies • Approaches for controlling change to libraries (Change Policies): • Informal (good for research type environments) • Formal approach (good for externally developed CIs and for releases) CS410 – Software Engineering Lecture #18: Rationale Management

Change Policies • Whenever a promotion or a release is performed, one or more policies apply. • The purpose of change policies is to guarantee that each version, revision or release (see next slide) conforms to commonly accepted criteria. • Examples for change policies: • “No developer is allowed to promote source code which cannot be compiled without errors and warnings.” • “No baseline can be released without having been beta-tested by at least 500 external persons.” CS410 – Software Engineering Lecture #18: Rationale Management

Version vs. Revision vs. Release • Version: • An initial release or re-release of a configuration item associated with a complete compilation or recompilation of the item. Different versions have different functionality. • Revision: • Change to a version that corrects only errors in the design/code, but does not affect the documented functionality. • Release: • The formal distribution of an approved version. CS410 – Software Engineering Lecture #18: Rationale Management

Tools for SCM • Software configuration management is normally supported by tools with different functionality. • Examples: • RCS: very old but still in use; only version control system • CVS: based on RCS, allows concurrent working without locking • Perforce: repository server; keeps track of developer’s activities • ClearCase: multiple servers, process modeling, policy check mechanisms CS410 – Software Engineering Lecture #18: Rationale Management

Tasks for the Configuration Managers SCMP following the IEEE 828-1990 standard Define configuration items Define promote /release policies Define responsibilities Set up configuration management system CS410 – Software Engineering Lecture #18: Rationale Management

Software Projects