Pengembangan Perangkat Lunak Metodologi dan Analisis Sistem

Sistem analisis adalah studi rinci dari sistem saat ini yang mengarah ke spesifikasi sistem baru. Analisis Sistem untuk '-toko e dalam kaleng' akan menggunakan pendekatan berorientasi objek untuk memungkinkan kami untuk model entitas kita pada objek dunia nyata dan membantu kita memahami dan mendokumentasikan karakteristik mereka. 

OOA akan memungkinkan rawatan melalui pemetaan disederhanakan ke dunia nyata, yang menyediakan untuk usaha analisis kurang, kompleksitas kurang dalam desain sistem, dan verifikasi lebih mudah oleh pengguna, reusability dari artefak analisis yang menghemat waktu dan biaya, dan tergantung pada metode analisis dan bahasa pemrograman, peningkatan produktivitas melalui pemetaan langsung ke fitur Object-Oriented Bahasa Pemrograman. 

Berorientasi objek vs berorientasi Proses analisis 

Proses analisis berorientasi menggambarkan sistem sebagai suatu jaringan proses berinteraksi. Ini mencakup deskripsi data yang digunakan oleh proses-proses, yang dicatat dalam kamus data. Pendekatan ini sering mengarahkan analis jauh dari mempelajari komponen sistem dan hubungan mereka terhadap mempelajari bagaimana sistem akan dirancang dan dilaksanakan. Hal ini juga sulit untuk analisis proses-berorientasi pada konsep peta antara jaringan proses dan obyek yang sudah ada dalam sistem dunia nyata. 

Berbeda dengan proses yang berorientasi analisis, analisis berorientasi objek modularizes dokumen analisis sepanjang batas objek yang sama yang ada dalam sistem dunia nyata. Selain itu, pendekatan ini juga mengatur semua pengetahuan tentang setiap objek sistem di lokasi logis tunggal dalam dokumen analisis. Dengan demikian, informasi tentang objek sistem lebih mudah untuk menemukan dalam analisis berorientasi objek dibandingkan metode analisis lainnya. Pendekatan berorientasi objek juga mendorong analis untuk berkonsentrasi pada "apa" daripada "bagaimana", yang mengurangi godaan untuk melompat sebelum waktunya untuk merancang. Untuk membuatnya lebih mudah untuk memahami informasi tentang obyek, teknik berorientasi objek memberikan bentuk abstraksi termasuk agregasi, generalisasi dan klasifikasi. 

Wawancara, pengamatan di lapangan dan kuesioner hanya beberapa alat yang akan juga digunakan untuk analisis sistem. 

Ini akan membuat lebih mudah untuk menarik batas yang tepat dari '-toko e dalam kaleng' dan memungkinkan kita untuk: 

Menjaga dalam melihat masalah dan persyaratan baru 

Workout pro dan kontra termasuk daerah-daerah baru dari sistem 

Selama analisis sistem kami akan melihat pendekatan baru untuk merancang e-commerce situs web, dengan cakupan diperluas antarmuka pengguna grafis (GUI) desain dengan perhatian yang dibuat untuk navigasi pada layar mudah. Analisis sistem akan memungkinkan kita untuk mencari cara melaksanakan keamanan website dan perlindungan privasi termasuk firewall, kebijakan perusahaan, SSL, dll 

Pada DOTNUTSHELL , kami memahami bahwa sistem analisis pada akhirnya akan mengarah pada penilaian risiko yang akan memungkinkan kita untuk mengidentifikasi potensi risiko dari sistem dan meningkatkan alokasi sumber daya keputusan.

(ArticlesBase SC # 322630)

SUMBER : http://www.articlesbase.com/software-articles/software-development-methodologies-and-system-analysis-322630.html

Strategi analisis dan desain sistem dalam kerangka keseluruhan sistem manajemen manufaktur

Author: Bin Wu ^sebuah

Abstrak Manajemen Sistem Manufaktur (MSM) dapat didefinisikan sebagai suatu domain fungsional yang melibatkan semua kegiatan (seperti desain, implementasi, operasi dan pengawasan) yang diperlukan untuk mengatur dan mengoptimalkan sistem manufaktur karena kemajuan melalui siklus hidupnya. Kerangka yang diusulkan sebelumnya telah menetapkan bidang fungsional utama MSM, menguraikan isi dan hubungan dalam diri mereka, dan kemudian secara logis mengintegrasikan ini ke dalam sebuah loop tertutup untuk memberikan dasar bagi pengembangan seperangkat parameter yang konsisten dan prosedur. Salah satu unsur penting dari kerangka kerja ini adalah Strategi Manufaktur Analysis (MSA) Desain Sistem Manufaktur (MSD) interface, yang membantu untuk masalah manufaktur mengasosiasikan strategis dengan persyaratan desain sistem berikutnya. Tulisan ini menentukan struktur model / MSA MSD berinteraksi dalam konteks kerangka MSM.Memberikan panduan langkah-demi-langkah melalui MSA lengkap / siklus MSD, model didasarkan pada hasil dari analisis luas tentang metodologi yang relevan dan teknik yang tersedia dalam literatur, dan data dikumpulkan melalui praktek industri. Berikut deskripsi dari proses fungsionalitas, dan alat-alat sepanjang / siklus MSA MSD, berbagai fitur baru model ini akan dibahas dan sejumlah studi kasus akan disajikan untuk menggambarkan aplikasi praktis.

SUMBER : www.ranslate.googleusercontent.com

Management, system analysis, IT and Internet technologies

Has come it is time to bury the read book. It is necessary to take the new book in library, and to get acquainted with new characters, ideas, experiences. The pleasure from comprehension novel will be received not only you, my dear reader, but also me, as the author of the new book. 

I do not wish to forget the old. I will find the ideas most interesting, in my opinion, in the old site, and I will try to develop them in the future. Naturally, I will write abouteffective management , the system analysis . Information systems and the technology Internet also will be included in sphere of my researches. How without them? I have devoted them the professional work. 

There is still an important point in my further analysis of that was. Namely, I as anysystem develop. And this development concerns my already formulated ideas. Some of them require development, others require reconsideration, the third have simply lost the urgency, the fourth have appeared are impractical and about them I will not write. 

To find out what ideas are most interesting to my readers, I have taken advantage of the analytical tool developed by me for the analysis Internet . Though I will agree, that sometimes, the phenomena which today the person does not understand - appear tomorrow basic for activity of the person. 

It is a question of a series of articles about 

Internet-Audit. Bobrovnikov's rule. Part 2. Audit on the basis of the analysis of representation on the Internet. 

It is natural, that the technology Internet are a component of information technologies. Being the expert in information technologies and having studied in this branch more than 20 years, I attended to different aspects of working out and introduction ofinformation systems . Accordingly, I have accumulated an extensive material on this subject. A part of my understanding, that such information technologies in global sense and their role in I modern business have stated in a series of articles. For example, 

System analysis. Management by end results of activity (MERA). Computer science and the Internet. 

The effective utilisation of information technologies cannot be without good understanding of structure of business, bases of its functioning. I write about thesystem analysis , as the tool of research and modelling business of processes. In particular, 

Systems analysis. Management by end results of activity (MERA). Introduction. 

It is not necessary to believe, that system research is reduced only to use of tools of the system analysis . Inherently the system is more difficult, than we assume, and it certain laws of development which we not in forces to change are inherent. It is a question of it in several my articles. 

In our world many events are predetermined in advance. Suddenly does not occur there is nothing. Before any event (including some events and the phenomena which signal us about troubles occur accidents). It is necessary to concern sensitively only world around, to try to notice all signals which to us are sent by system . Problems will be less. About it I write in the article 

Together with system or scientific fortunetelling. 

The article 

Model of stable conditions and developments of a system (states, parties, firms) 

tells about that the system develops in the certain recurrence connected with comprehension by system who it such. It is a question of process of accumulation and devaluation of knowledge (information) . It is my attempt to answer a question, and why the mankind history develops so (as developed), instead of differently. In the article I have drawn a cut of space of development of system . In realities, systemdevelopment has a spiral appearance. If to "pierce" my diagramme a line designating time, and to use a continuity principle we will receive a spiral (it reminds a spindle on which the history of development of human community "is reeled up", of it in the future). 

My old site was initially devoted to effective management which cannot be constructed without an effective system of management . That I understand as it is in details described in the article 

Introduction, ie what I mean by effective management systems. 

Of management we do not think without understanding of the basic tools with which help it is under construction: a consensus, the compromise, authoritarianism. It is a question of it in the article 

Review and classification of management systems. 

In the article 

Problems, aims and tasks in business 

it is a question of main principles of the planning, applied in management . Including I tried to realise a ratio between strategy and tactics. 

About management it is possible to argue as on the exact science, so about art. I tried to look at control systems under both foreshortenings. That to speak aboutmanagement as about the exact science I had to think up the interesting mathematical tool 

Rarefied sets. 

The idea consists in the following. For unequivocal system we can connect the phenomena among themselves and, accordingly, probabilities. In case of complex and ambiguous system it is difficult to reveal all interrelations. I suggest to analyze two likelihood characteristics: the probability "yes" and probability "is not present" (following logic to a design: without delay yes, than is not present and without delay is not present, than yes). 

You ask and here management ? On this question I have answered in the article 

Logic of business organization. 

I have tried to connect among themselves diverse concepts: theories of sets, planning principles in management , systems of decision-making and business managementstructure. 

In general management can be compared in any sense to a live organism in which certain "diseases" - deformations are inherent. Partially I have described them in the article 

Defects of management hierarchies, 

assuming, that any company is, from a part self-organised by system (about it there is a speech in the article 

Organization and Business Management Model). 

Management closely related with information technologies . Today, I am convinced,effective management is impossible without correct and optimum use of information technologies in which basis is: 

Information policy of the company. Addition. Concept of uniform information space. 

(I have tried to construct the generalised conceptual model of an information system). Use of information technologies should be optimised under budgets: service of users, a server economy, networks, the industrial software, ERP, etc. 

I have tried to glance in the conceptual future information and the Internet oftechnologies . It seems to me, that the IT world is today in some technologicalstagnation connected with effect of rigid division of mankind on consumers and suppliers of information technologies . The parity between the pro and not the pro in a IT has reached the saturation, the new sight at old things accordingly to "push" progress is required. About it I write in the article 

Consulting system on solution of problems on business with usage of Internet technologies. Knowledge base. Setting of the task. 

If want, it is my professional dream - to realise this project. 

There can be an impression, that me interests only the general, theoretical positions. It not so. The majority of my ideas, is the conclusions gained in practice. Behind each such "opening" there are certain people, events and firms. That in details to describe situations which have helped me to understand essence of this or that event it is required to write the big work. On it I do not have means and, hence, time. My site and researches is a personal initiative which, hopes, has helped, will help and will help with uneasy business of the organisation of effective management (including with useinformation and the Internet of technologies) .

Sincerely yours, Pavel Bobrovnikov

SUMBER : http://www.ironya.com/

Keterampilan Teknis di Analisis Sistem

Oleh Erin Moseley , eHow Kontributor

diperbaharui: April 8, 2010

1.      Sistem analis tidak perlu hanya untuk menunjukkan kemampuan besar komunikasi, tenang dan motivasi diri, tetapi juga memiliki keterampilan teknis yang berkembang dengan baik. keterampilan teknis yang kuat akan melihat analis melalui masalah yang paling sulit. College kursus dan sertifikasi semuanya memberikan latar belakang yang besar bagi para analis, dan pekerjaan pengalaman datang hanya dengan waktu. Bahasa pemrograman yang lebih, komputer program dan sistem operasi mereka belajar, lebih baik disesuaikan mereka adalah untuk petualangan berikutnya.

Performance Tuning

 

2.      Komputer, router, program dan jaringan yang dikonfigurasi untuk menyediakan kondisi kerja yang terbaik bagi karyawan. Analis perlu memahami bagaimana segala sesuatu di situs tersebut bekerja sama dan dapat menyempurnakan dan meningkatkan wilayah yang membutuhkan perhatian. Pemantauan kemacetan yang memperlambat produktivitas perusahaan ke bawah dan kemudian menyesuaikan program sistem untuk mengatasi masalah adalah dalam pekerjaan sehari-hari.

 

3.      Bahasa Pemrograman

Pengetahuan dan keakraban dengan bahasa pemrograman umum seperti C + + dan Java berguna di tempat kerja. Sistem analis tidak selalu perlu untuk melakukan coding, tetapi mereka harus mampu membacanya. Dengan cara itu mereka dapat membicarakannya dengan programmer yang bertanggung jawab untuk memodifikasi itu.

4.      Komputer Platform

Keakraban dengan sistem operasi seperti AIX, Windows, Mac dan Linux berguna dalam lingkungan yang menggunakan teknologi banyak atau jika pekerjaan memerlukan banyak perjalanan.

5.      Kemampuan Hardware

pengetahuan yang mendalam tentang jenis perangkat keras yang digunakan pada setiap tempat kerja diperlukan untuk analis sistem untuk memastikan sejauh mana masalah komputer dan kerusakan peralatan mungkin. Pengetahuan tentang kapasitas penyimpanan dan komputasi komputer, routing peralatan, printer dan perangkat eksternal dan Bluetooth dapat membantu para karyawan terus bekerja sambil perbaikan dilakukan.

6.      Struktur dan Fungsi Jaringan

Analis menangani komputer di jaringan, sehingga hanya logis bahwa mereka akrab dengan topologi jaringan, atau struktur, dan juga bagaimana mengelola jaringan. Keterampilan semacam ini umumnya diperoleh pada pekerjaan dan juga melalui kelas yang diajarkan oleh perusahaan-perusahaan yang memproduksi jaringan perangkat lunak.

7.      Struktur data

Data mana-mana di tempat kerja, dan database yang umum di semua perusahaan, besar dan kecil. database proprietary dan perusahaan yang lebih umum seperti Oracle dan Foxpro digunakan di seluruh industri didasarkan pada struktur data yang serupa.

8.      Keamanan Komputer

pelanggaran keamanan yang lebih umum dari sebelumnya, dan analis membantu menjaga komputer bebas dari virus dan gangguan invasif lainnya. Mereka membantu mengembangkan strategi untuk memastikan di tempat integritas data. Analis membantu menentukan kebijakan perusahaan mengenai keamanan komputer seperti tidak membiarkan karyawan untuk men-download perangkat lunak ke jaringan.

SUMBER : http://translate.googleusercontent.com

Persyaratan untuk Karir sebagai suatu Analisis Sistem Komputer

Dengan Keith Evans , eHow Kontributor

diperbaharui: 25 Mei 2010

1.                           

Desain sistem komputer sistem analis bagi pengguna akhir.

Sistem komputer kunci analis adalah anggota staf TI, bekerja untuk membantu merancang dan mengimplementasikan sistem komputer bagi pengguna akhir dan untuk memecahkan masalah. Calon analis sistem komputer harus mempertahankan beragam keterampilan dan keahlian. Dari maju pendidikan dan pelatihan spesifik industri untuk kemampuan interpersonal yang baik, analis sistem komputer masa depan harus memiliki keterampilan mengatur bulat baik yang akan memenuhi semua kebutuhan majikan.

Pendidikan

2.                              Sebuah komputer sistem analis harus memiliki cukup tinggi pasca- sekolah pendidikan untuk menarik calon majikan. Meskipun persyaratan pendidikan bervariasi dari majikan ke majikan, Biro Tenaga Kerja AS dan Statistik poin bahwa majikan biasanya lebih memilih pelamar dengan setidaknya gelar empat tahun. Lebih khusus lagi, menurut pendidikan referensi website StateUniversity.com, pengusaha umumnya mencari pelamar yang memiliki sarjana atau gelar master di bidang komputer-terkait seperti ilmu komputer, ilmu informasi atau rekayasa.

Pelatihan dan Sertifikasi

3.                              Selain pendidikan formal, pengusaha biasanya mengharapkan pelamar untuk memiliki pelatihan komputer khusus khusus. Tergantung pada sistem lebih memilih majikan dan kontrak vendor, menurut referensi kerja situs CareerOverview.com, pengusaha lebih memilih pelamar yang memegang CompTIA A + komputer sertifikasi, Microsoft Certified Systems Engineer (MCSE) atau Cisco Certified Network Associate (CCNA) sertifikasi. Selain itu, menurut CareerOverview.com, pengusaha mengharapkan sistem komputer analis untuk mempertahankan mata uang dan kemahiran dalam industri dengan mendaftar di melanjutkan pendidikan. Perubahan industri teknologi pesat, dan banyak karyawan dalam peran analis sistem komputer harus mendaftarkan diri dalam melanjutkan pendidikan setiap beberapa tahun dalam rangka untuk tetap mengikuti inovasi-inovasi baru.

Pengalaman

4.                              Calon analis sistem komputer harus memiliki pengalaman yang cukup besar, meskipun mereka mungkin memperoleh pengalaman di beberapa bidang yang berhubungan dengan komputer. Menurut StateUniversity.com, komputer banyak sistem analis transfer ke karir dari jalur lain kerja, beberapa baris ini termasuk pemrograman komputer dan pengolahan data. Selain itu, beberapa pengusaha mungkin membutuhkan pengalaman tambahan yang terkait dengan pengusaha bisnis utama. Sebuah komputer sistem analis yang bekerja di bank, misalnya, mungkin perlu beberapa pengalaman keuangan. Seorang analis yang bekerja untuk sebuah perusahaan manufaktur mungkin perlu beberapa pengalaman dalam industri.

Interpersonal Keterampilan

5.                              Sistem komputer analis menghabiskan sebagian yang baik dari hari mereka bekerja dengan pengguna akhir sistem ini, menurut US News and World Report. Untuk alasan ini, analis sistem komputer calon harus memiliki kemampuan interpersonal yang sangat baik. Dalam beberapa kasus, keterampilan ini membantu analis industri menerjemahkan jargon yang sangat spesifik dan istilah non-teknis menjadi informasi yang berguna bagi technophiles komputer yang akan merancang sistem pengguna. Selain itu, analis harus bekerja secara langsung dengan semua pengguna akhir sistem, dan persyaratan ini dapat mengekspos analis untuk beragam tipe kepribadian dan tingkat keterampilan teknis. Untuk benar berkomunikasi dengan berbagai pengguna, analis harus mempertahankan kemampuan interpersonal yang luar biasa.

Keterampilan Organisasi

6.                              Saat bekerja dengan pengguna untuk mengidentifikasi kebutuhan dan mengimplementasikan sistem yang baru dirancang, analis sistem komputer harus mampu mengidentifikasi, mendokumentasikan dan mengkomunikasikan semua aspek dari sistem baru pengguna. Karena banyak sistem menjadi sangat kompleks, tugas ini memerlukan keterampilan organisasi yang luar biasa.

SUMBER : http://translate.googleusercontent.com

System Analysis - Stages in the System Development Life Cycle

Stages in the Systems Development Life Cycle

The systems life cycle models the stages involved in developing an Information technology system. The system life cycle may be looked at as a 7 phase- problem solving procedure. 
These stages are:

• Initiation
• Preliminary Investigation
• System Analysis
• System Design
• System Development
• System Implementation
• System Maintenance

Initiation Stage

This is the first stage of the system life cycle and it involves finding out all about the existing system . Problems (limitations) with the existing systems are determined, and possible solutions are identified. This leads to a feasibility study which involves, costing, timescales, hardware and software requirements and staffing issues.

Investigation Stage

This stage is often referred to as the preliminary investigation stage, in which case the problems are defined, the scope of the system is determined, alternative solutions are suggested and a short report is produced.

Analysis Stage

Within this stage, data is collected and a deeper look (study) of the existing system is done. Data collection may be done through observation, interviews, document analysis and questionnaires.

Modeling tools are then used to analyze the system and new requirements are defined. 
Modeling tools may include checklists, structural diagrams such as top-down analysis methodology, flow charts, grid charts and decision tables. Others are automated design tools such as computer-aided software engineering tools (CASE) which help system analysts to evaluate hardware and software alternatives. 
At the end of this analysis, findings are documented. The documentation of these findings includes the description and scope of the existing system, the requirement of the new system and a proposed development programme or schedule is produced.

Design Stage

The design stage takes into consideration all the information gathered in the previous stages and uses this information to produce a technical document which is often referred to as the system specification. 
Before the report or specification is produced however, alternative designs are evaluated. The evaluation of the designs involves economic, technical and operational feasibility. Economic consideration will include cost benefit analysis, while operational and technical evaluation will consider among others flexibility, scalability, integration and security. 
At the end, a report is also produced which will include alternative designs and a recommendation.

System Development

The system specification developed in the design stage is used to develop the system. Under system development, two options are considered; this involves the type of developing software to use. This may be:

• A packaged software (off-the shelf) eg Microsoft access software
• Custom design software (bespoke)

This stage will also take in to consideration the hardware that is needed and the installation process. 
The last step of this stage may also include the testing of the new system in which case sample data are fed into the system and the results are evaluated to ensure that the system is working according to specification.

System Implementation

The system implementation stage involves the installation of the system, staff training and conversion. There are different types of conversion plan, these are:

• Direct approach: the old system is completely abandoned and a new one takes it place.
• Parallel approach : Just as the name implies the old and the new systems are operated concurrently. This continues until the new system proves that it can be operated on its own and that it is works according to specification.
• Pilot approach: This is when the new system is launched in just one sector or department of the entire organization or business. If the system works according to specification, it will then be implemented fully.

Note:

Stages of a system life cycle may differ depending on a given model. While some stages are separated in one model, they may be merged in another. The main point here is to understand what these stages involve and their roles in the development of information systems .

SUMBER : http://www.divinekonection.info/articles/System-Analysis---Stages-in-the-System-Development-Life-Cycle-a14.html

Structured Systems Analysis and Design Method

Overview

SSADM is a waterfall method by which an Information System design can be arrived at. SSADM can be thought to represent a pinnacle of the rigorous document-led approach to system design, and contrasts with more contemporary Rapid Application Development methods such as DSDM .

SSADM is one particular implementation and builds on the work of different schools of structured analysis and development methods, such as Peter Checkland's Soft Systems Methodology , Larry Constantine's Structured Design , Edward Yourdon's Yourdon Structured Method , Michael A. Jackson's Jackson Structured Programming , and Tom DeMarco'sStructured Analysis .

The names "Structured Systems Analysis and Design Method" and "SSADM" are now Registered Trade Marks of the Office of Government Commerce (OGC), which is an Office of the United Kingdom's Treasury. ^{[ citation needed ]}

[ edit ]History

§                     1980: Central Computer and Telecommunications Agency (CCTA) evaluate analysis and design methods.

§                     1981: Learmonth & Burchett Management Systems (LBMS) method chosen from shortlist of five.

§                     1983: SSADM made mandatory for all new information system developments

§                     1984: Version 2 of SSADM released

§                     1986: Version 3 of SSADM released, adopted by NCC

§                     1988: SSADM Certificate of Proficiency launched, SSADM promoted as 'open' standard

§                     1989: Moves towards Euromethod, launch of CASE products certification scheme

§                     1990: Version 4 launched

§                     1993: SSADM V4 Standard and Tools Conformance Scheme Launched

§                     1995: SSADM V4+ announced, V4.2 launched

[ edit ]SSADM techniques

The three most important techniques that are used in SSADM are:

Logical Data Modeling

This is the process of identifying, modeling and documenting the data requirements of the system being designed. The data are separated into entities (things about which a business needs to record information) and relationships (the associations between the entities).

Data Flow Modeling

This is the process of identifying, modeling and documenting how data moves around an information system. Data Flow Modeling examines processes (activities that transform data from one form to another), data stores (the holding areas for data), external entities (what sends data into a system or receives data from a system), and data flows (routes by which data can flow).

Entity Behavior Modeling

This is the process of identifying, modeling and documenting the events that affect each entity and the sequence in which these events occur.

[ edit ]Stages

The SSADM method involves the application of a sequence of analysis, documentation and design tasks concerned with the following.

[ edit ]Stage 0 - Feasibility study

In order to determine whether or not a given project is feasible, there must be some form of investigation into the goals and implications of the project. For very small scale projects this may not be necessary at all as the scope of the project is easily apprehended. In larger projects, the feasibility may be done but in an informal sense, either because there is not time for a formal study or because the project is a “must-have” and will have to be done one way or the other.

When a feasibility study is carried out, there are four main areas of consideration:

§         Technical - is the project technically possible?

§         Financial - can the business afford to carry out the project?

§         Organizational - will the new system be compatible with existing practices?

§         Ethical - is the impact of the new system socially acceptable?

To answer these questions, the feasibility study is effectively a condensed version of a fully-blown systems analysis and design. The requirements and users are analyzed to some extent, some business options are drawn up and even some details of the technical implementation.

The product of this stage is a formal feasibility study document. SSADM specifies the sections that the study should contain including any preliminary models that have been constructed and also details of rejected options and the reasons for their rejection.

[ edit ]Stage 1 - Investigation of the current environment

This is one of the most important stages of SSADM. The developers of SSADM understood that though the tasks and objectives of a new system may be radically different from the old system, the underlying data will probably change very little. By coming to a full understanding of the data requirements at an early stage, the remaining analysis and design stages can be built up on a firm foundation.

In almost all cases there is some form of current system even if it is entirely composed of people and paper. Through a combination of interviewing employees, circulating questionnaires, observations and existing documentation, the analyst comes to full understanding of the system as it is at the start of the project. This serves many purposes:

§         the analyst learns the terminology of the business, what users do and how they do it

§         the old system provides the core requirements for the new system

§         faults, errors and areas of inefficiency are highlighted and their reparation added to the requirements

§         the data model can be constructed

§         the users become involved and learn the techniques and models of the analyst

§         the boundaries of the system can be defined

The products of this stage are:

§         Users Catalogue describing all the users of the system and how they interact with it

§         Requirements Catalogues detailing all the requirements of the new system

§         Current Services Description further composed of

§         Current environment logical data structure (ERD)

§         Context diagram (DFD)

§         Levelled set of DFDs for current logical system

§         Full data dictionary including relationship between data stores and entities

To produce the models, the analyst works through the construction of the models as we have described. However, the first set of data-flow diagrams (DFDs) are the current physical model, that is, with full details of how the old system is implemented. The final version is the current logical model which is essentially the same as the current physical but with all reference to implementation removed together with any redundancies such as repetition of process or data.

In the process of preparing the models, the analyst will discover the information that makes up the users and requirements catalogues.

[ edit ]Stage 2 - Business system options

Having investigated the current system, the analyst must decide on the overall design of the new system. To do this, he or she, using the outputs of the previous stage, develops a set of business system options. These are different ways in which the new system could be produced varying from doing nothing to throwing out the old system entirely and building an entirely new one. The analyst may hold a brainstorming session so that as many and various ideas as possible are generated.

The ideas are then collected to form a set of two or three different options which are presented to the user. The options consider the following:

§         the degree of automation

§         the boundary between the system and the users

§         the distribution of the system, for example, is it centralized to one office or spread out across several?

§         cost/benefit

§         impact of the new system

Where necessary, the option will be documented with a logical data structure and a level 1 data-flow diagram.

The users and analyst together choose a single business option. This may be one of the ones already defined or may be a synthesis of different aspects of the existing options. The output of this stage is the single selected business option together with all the outputs of stage 1.

[ edit ]Stage 3 - Requirements specification

This is probably the most complex stage in SSADM. Using the requirements developed in stage 1 and working within the framework of the selected business option, the analyst must develop a full logical specification of what the new system must do. The specification must be free from error, ambiguity and inconsistency. By logical, we mean that the specification does not say how the system will be implemented but rather describes what the system will do.

To produce the logical specification, the analyst builds the required logical models for both the data-flow diagrams (DFDs) and the entity relationship diagrams (ERDs). These are used to produce function definitions of every function which the users will require of the system, entity life-histories (ELHs) and effect correspondence diagrams, these are models of how each event interacts with the system, a complement to entity life-histories. These are continually matched against the requirements and where necessary, the requirements are added to and completed.

The product of this stage is a complete Requirements Specification document which is made up of:

§         the updated Data Catalogue

§         the updated Requirements Catalogue

§         the Processing Specification which in turn is made up of

§         user role/function matrix

§         function definitions

§         required logical data model

§         entity life-histories

§         effect correspondence diagrams

Though some of these items may be unfamiliar to you, it is beyond the scope of this unit to go into them in great detail.

[ edit ]Stage 4 - Technical system options

This stage is the first towards a physical implementation of the new system. Like the Business System Options, in this stage a large number of options for the implementation of the new system are generated. This is honed down to two or three to present to the user from which the final option is chosen or synthesised.

However, the considerations are quite different being:

§         the hardware architectures

§         the software to use

§         the cost of the implementation

§         the staffing required

§         the physical limitations such as a space occupied by the system

§         the distribution including any networks which that may require

§         the overall format of the human computer interface

All of these aspects must also conform to any constraints imposed by the business such as available money and standardisation of hardware and software.

The output of this stage is a chosen technical system option.

[ edit ]Stage 5 - Logical design

Though the previous level specifies details of the implementation, the outputs of this stage are implementation-independent and concentrate on the requirements for the human computer interface.

The three main areas of activity are the definition of the user dialogues. These are the main interfaces with which the users will interact with the system. The logical design specifies the main methods of interaction in terms of menu structures and command structures.

The other two activities are concerned with analyzing the effects of events in updating the system and the need to make enquiries about the data on the system. Both of these use the events, function descriptions and effect correspondence diagrams produced in stage 3 to determine precisely how to update and read data in a consistent and secure way.

The product of this stage is the logical design which is made up of:

§         Data catalogue

§         Required logical data structure

Logical process model which includes dialogues and model for the update and enquiry processes

[ edit ]Stage 6 - Physical design

This is the final stage where all the logical specifications of the system are converted to descriptions of the system in terms of real hardware and software. This is a very technical stage and an simple overview is presented here.

The logical data structure is converted into a physical architecture in terms of database structures. The exact structure of the functions and how they are implemented is specified. The physical data structure is optimized where necessary to meet size and performance requirements.

The product is a complete Physical Design which could tell software engineers how to build the system in specific details of hardware and software and to the appropriate standards.

[ edit ]Advantages and disadvantages

Using this methodology involves a significant undertaking which may not be suitable to all projects.

The main advantages of SSADM are:

§         Three different views of the system

§         Mature

§         Separation of logical and physical aspects of the system

§         Well-defined techniques and documentation

§         User involvement

The size of SSADM is a big hindrance to using it in all circumstances. There is a large investment in cost and time in training people to use the techniques. The learning curve is considerable as not only are there several modeling techniques to come to terms with, but there are also a lot of standards for the preparation and presentation of documents.

SUMBER: http://en.wikipedia.org/wiki/Structured_Systems_Analysis_and_Design_Method