Ko'proq

Ko'p xususiyatli sinflarga asoslangan holda yangi xususiyat sinfini yarating

Ko'p xususiyatli sinflarga asoslangan holda yangi xususiyat sinfini yarating


Kimdir shunga o'xshash savol beradimi yoki yo'qligini bilish uchun avvalgi xabarlarni qidirib topdim, ammo hech narsa topmadim. Menda bir nechta xususiyatli sinflar mavjud, ularning har biri bir nechta ko'pburchaklarni o'z ichiga oladi. Menda ikkita kerakli natijalar mavjud:

A) Mening kirish qatlamlarimning 50% dan ko'prog'i kesishgan joylarda yangi yagona xususiyatlar sinfini yaratishning oson usulini topmoqchiman. Menda mavjud bo'lgan qatlamlar soni har xil bo'ladi, ammo misol sifatida 6 dan foydalanamiz. Mening to'rtta kirish qatlamimning qaysi biri 50% dan ko'proq bo'lishidan qat'i nazar, bitta funktsiya sinfini yaratish yaxshi bo'lar edi. Men Intersect yordamida model yaratishga harakat qildim, ammo tizimdagi barcha 6 ta kirishlarning bir-biriga to'g'ri kelmasligi kerakligini aytadigan mantiqiy qismni etishmayapman, kamida to'rttasi.

B) Men istagan boshqa natijalar - bu mening kirishim asosida o'rtacha maydon bo'lgan yangi ko'pburchaklarni yaratadigan yangi xususiyatlar sinfi. Bunday holda men ushbu vositadan mening kiritgan ma'lumotlarimning 50% dan ko'prog'i ustma-ust keladigan maydonlarning matematik o'rtacha ko'rsatkichlari bilan yangi xususiyatlar sinfini yaratishni istardim. Men qidirib topdim, lekin menga hech qanday yordam beradigan bunday vositani topmadim.

Hozirda ArcInfo (Advanced) litsenziyam bor, ammo kengaytmalari yo'q. Maqsadlarimni ArcView (Basic desktop) yoki ArcInfo bilan amalga oshirishning biron bir usuli bo'lsa, afzalroq bo'ladi. Agar u erda kengaytma mavjud bo'lsa, men uning nima ekanligini bilishni xohlayman.


3 ko'pburchak qatlamiga asoslangan javob:

  1. Barcha qatlamlarni bitta ma'lumotlar to'plamiga birlashtirish (Geoprocessing-Merge), ALL_PGONS
  2. ALL_PGONS (Geoprosessing-Interters) bilan kesishish. Ikkinchi qavat yo'q, INTERSECT chiqishi
  3. INTERSECT jadvalida yangi matn maydonini yarating, uni LINKFLD deb nomlang
  4. Ushbu maydonni maydon kalkulyatori (Python) yordamida shunga o'xshash narsalar yordamida to'ldiring (siz taxmin qilingan tizim bilan ishlayapsiz deb o'ylayman):

    '% i% i'% (int (! Shape! .centroid.X), int (! Shape! .centroid.Y))

  5. INTERSECT jadvalida yangi qisqa maydon yarating, uni ONE deb nomlang

  6. LINKFLD maydonida saqlangan noyob qiymatlar sonini hisoblash uchun Xulosa statistikasidan foydalaning:

LINKFLD yordamida chiqish jadvalini (yuqoridagi misolda freq.dbf) INTERSECT jadvaliga qo'shiling. FREQUENCY yordamida kesishishni ramziy qilishingiz mumkin.

Shuningdek, siz qatlamlar sonining 50% dan yuqori bo'lgan ko'pburchaklarni tanlashingiz mumkin. Ularning darajasi sizning javobingiz.


Texnologiyani nafaqat ajoyib yangi narsa, balki o'quv vositasi sifatida ishlatish

Men birinchi marta AOL Instant Messenger-dagi "gapirish" xususiyati bo'yicha bobom va buvim bilan suhbatlashganda raqamli yoshni to'liq angladim. Nafaqat kompyuterga ega, balki undan qanday foydalanishni biladigan bobo-buvilarga ega bo'lish qanchalik yaxshi, deb o'yladim. Eng ajablanarli tomoni shundaki, mening bobom, hech qachon rasmiy texnikaviy ma'lumotga ega bo'lmagan, amakivachchamning yordami bilan qismlardan kompyuterlar, disk anakartlari, qattiq disklar va boshqalarni bitta emas, ikkitasini qurgan. U yuqori tezlikdagi Internetga ulangan, elektron pochta xabarlarini yuborgan va qabul qilgan, CD-disklarni yozgan va IM yordamida onlayn suhbat qurgan. U hatto mening buvim uchun kompyuter qurdi, u undan har kuni o'lim joylarini tekshirish uchun foydalanadi Uinston-Salem jurnali Veb-sayt va onlayn jumboqlarni bajaradi. U endi haqiqiy narsalarni qila olmaydi, chunki uning qismlari ko'rish va tushunish uchun juda kichikdir.


Shuningdek, siz sinf ob'ektini yaratishingiz va unga boshqa sinfda kirishingiz mumkin. Bu ko'pincha sinflarni yaxshi tashkil qilish uchun ishlatiladi (bir sinfda barcha maydonlar va usullar mavjud, boshqa sinfda Main () usuli mavjud (bajariladigan kod)).

Prog2.cs

Prog.cs

Ochiq kalit so'zni ko'rdingizmi? Bunga deyiladi kirish modifikatori, bu avtomobilning rang o'zgaruvchisiga / maydoniga boshqa sinflar uchun ham, masalan, Programma uchun ham kirish imkoniyatini beradi.

Siz haqida ko'proq ma'lumotga ega bo'lasiz kirish modifikatorlari va sinflar / ob'ektlar keyingi boblarda.


Yo'q, C # bir nechta merosni qo'llab-quvvatlamaydi. Siz bir nechta interfeyslarni amalga oshirishingiz mumkin, ammo bu aniq emas, chunki interfeyslarda aniq bir xatti-harakatlar amalga oshirilmaydi.

Buni C # -da Mixins orqali amalga oshirishingiz mumkin, u bir nechta merosga qaraganda boshqacha tarzda amalga oshiriladi, ammo oxirida siz bir nechta sinflarning barcha usullari bilan ob'ekt olasiz.

Bu tilning xususiyati emas, lekin uni uchinchi shaxslarda topish mumkin.

Bir nechta qiziqish:
- siz Mixin-da usullarni bekor qilishingiz mumkin, shu bilan yangi yaratilgan sinflarning xatti-harakatlarini tashqi tomondan o'zgartirasiz.
- doirada yaratilgan holda sinflar har xil bo'lgan doiralarni yaratishingiz mumkin.
- zavod orqali mixin'd moslamalarini yaratishingiz kerak (yangi MyObject () Mixinsni hisobga olmaydi).


Mundarija

Paradigma va o'ziga xos tilga asoslangan turli xil meros turlari mavjud. [7]

bu erda subklasslar bitta superklassning xususiyatlarini egallaydi. Sinf boshqa sinfning xususiyatlariga ega bo'ladi.

bu erda bitta sinf bir nechta superklassga ega bo'lishi va barcha ota-ona sinflaridan xususiyatlarni egallashi mumkin.

"Ko'plab merosxo'rlik. Keng miqyosda samarali amalga oshirilishi juda qiyin bo'lgan. Masalan, C ++ tilidagi qisqacha bayonotida S maqsadiga bag'ishlangan kitobida Bred Koks aslida C ++ ga bir nechta merosni qo'shib bo'lmaydi, deb da'vo qilgan. Shunday qilib, ko'p meros ko'proq tuyuldi. Men juda ko'p merosni 1982 yilidayoq ko'rib chiqqanim va 1984 yilda sodda va samarali amalga oshirish usulini topganim sababli, men bu muammoga qarshi tura olmadim. Men bu voqealar ketma-ketligiga ta'sir qiladigan yagona holat deb o'ylayman. " [8]

bu erda subklass boshqa subklassdan meros bo'lib olinadi. "Ko'p darajali meros" rasmida ko'rsatilgandek, sinf boshqa hosil bo'lgan sinfdan kelib chiqishi odatiy holdir.

Sinf A sifatida xizmat qiladi asosiy sinf uchun olingan sinf B, bu esa o'z navbatida a vazifasini bajaradi asosiy sinf uchun olingan sinf C. Sinf B sifatida tanilgan oraliq asosiy sinf, chunki u o'rtasidagi meros uchun bog'lanishni ta'minlaydi A va C. Zanjir ABC sifatida tanilgan meros yo'li.

Ko'p darajali merosga ega bo'lgan kelib chiqqan sinf quyidagicha e'lon qilinadi:

Ushbu jarayon istalgan darajaga kengaytirilishi mumkin.

Bu erda bitta sinf bir nechta kichik sinflar uchun superklass (asosiy sinf) bo'lib xizmat qiladi. Masalan, ota-ona A sinfida ikkita B va C kichik sinflari bo'lishi mumkin, B va C ning ota-onalari ikkalasi ham A, lekin B va C ikkita alohida kichik sinflardir.

Gibrid meros - bu yuqoridagi ikki yoki undan ortiq turdagi merosning aralashmasi sodir bo'lganda. Bunga misol qilib, A sinfida B va C ikkita D subklasslari bo'lgan subklass mavjud. Bu ko'p darajali meros va ierarxik merosning aralashmasi.

Subklasslar, olingan sinflar, merosxo'r sinflari, yoki bolalar sinflari bir yoki bir nechta til sub'ektlarini bir yoki bir nechta boshqa sinflardan meros qilib olgan modulli lotin sinflari (deyiladi superklass, tayanch sinflar, yoki ota-onalar uchun darslar). Sinf merosining semantikasi har bir tilda turlicha bo'ladi, lekin odatda subklass o'z superklasslarining misol o'zgaruvchilari va a'zo funktsiyalarini avtomatik ravishda meros qilib oladi.

Hosil qilingan sinfni aniqlashning umumiy shakli: [9]

  • Yo'g'on ichak subklassning superklassdan meros bo'lib o'tishini bildiradi. Ko'rinish ixtiyoriy va agar mavjud bo'lsa, u ham bo'lishi mumkin xususiy yoki jamoat. Odatiy ko'rinish xususiy. Ko'rinish tayanch sinfining xususiyatlari ekanligini aniqlaydi xususiy olingan yoki ommaviy ravishda olingan.

Ba'zi tillar boshqa konstruktsiyalarning merosini ham qo'llab-quvvatlaydi. Masalan, Eyfelda sinfning spetsifikatsiyasini belgilaydigan shartnomalar ham merosxo'rlar tomonidan meros qilib olinadi. Superklass ixtisoslashgan subklasslar meros qilib olishi, o'zgartirishi va to'ldirishi mumkin bo'lgan umumiy interfeys va asosiy funktsionallikni o'rnatadi. Subklassga meros qilib olingan dastur subklassda qayta ishlatilgan hisoblanadi. Sinfning namunasiga havola, aslida uning subklasslaridan biriga tegishli bo'lishi mumkin. Ob'ektning haqiqiy sinfini kompilyatsiya vaqtida taxmin qilish mumkin emas. Yagona interfeys bir qator turli xil sinflar ob'ektlarining a'zo funktsiyalarini chaqirish uchun ishlatiladi. Subklasslar superklass funktsiyalarini bir xil uslub imzolarini taqsimlashi kerak bo'lgan mutlaqo yangi funktsiyalar bilan almashtirishi mumkin.

Subclassable bo'lmagan sinflar Edit

Ba'zi tillarda sinf deklaratsiyasiga ma'lum sinf modifikatorlarini qo'shish orqali sinf subklassable deb e'lon qilinishi mumkin. Masalan, Java va C ++ 11 da yakuniy kalit so'z yoki C # da muhrlangan kalit so'z. Bunday modifikatorlar sinf deklaratsiyasiga sinf kalit so'zi va sinf identifikatori deklaratsiyasidan oldin qo'shiladi. Bunday sinflarga bo'linmaydigan sinflar qayta ishlashni cheklaydi, ayniqsa, ishlab chiquvchilar faqat oldindan tuzilgan ikkiliklarga kirish huquqiga ega bo'lsalar, manba kodlari emas.

Subclassable bo'lmagan sinfda subclasslar mavjud emas, shuning uchun kompilyatsiya vaqtida ushbu sinf ob'ektlariga havolalar yoki ko'rsatgichlar aslida ushbu sinfning misollariga havola qilinganligi va subklasslar (ular mavjud emas) yoki superklasslarning misollari emasligi osonlikcha chiqarilishi mumkin. (mos yozuvlar turini rad etish, tizim tizimini buzadi). Ob'ektning aniq turi bajarilishidan oldin ma'lum bo'lganligi sababli, kech bog'lanish o'rniga (shuningdek, dinamik dispetcherlik deb ataladi) erta majburiy (statik dispetcherlik) ishlatilishi mumkin, bu bir nechta merosga bog'liq ravishda bir yoki bir nechta virtual usul jadvallarini qidirishni talab qiladi. yoki ishlatilayotgan dasturlash tilida faqat bitta meros qo'llab-quvvatlanadi.

O'chirib bo'lmaydigan usullar Tartibga solish

Sinflar subklassga bo'linmasligi mumkin bo'lganidek, usul deklaratsiyalari ham metodni bekor qilishni oldini oladigan usul modifikatorlarini o'z ichiga olishi mumkin (ya'ni subklassda xuddi shu nom va turdagi imzo bilan yangi funktsiya bilan almashtiriladi). Xususiy usulni bekor qilish mumkin emas, chunki unga boshqa sinflar kirishlari mumkin emas, chunki bu uning a'zosi funktsiyasidir (bu C ++ uchun to'g'ri emas). Java-da yakuniy usul, C # -da muhrlangan usul yoki Eyfelda muzlatilgan xususiyat bekor qilinishi mumkin emas.

Virtual usullarni tahrirlash

Agar superklass usuli virtual usul bo'lsa, u holda superklass uslubining chaqiruvlari dinamik ravishda yuboriladi. Ba'zi tillar usullarni maxsus virtual deb e'lon qilishni talab qiladi (masalan, C ++), boshqalarda esa barcha usullar virtual (masalan, Java). Virtual bo'lmagan usulni chaqirish har doim statik ravishda yuboriladi (ya'ni funktsiya chaqiruvining manzili kompilyatsiya vaqtida aniqlanadi). Statik dispetcherlik dinamik yuborishdan tezroq va inline kengayish kabi optimallashtirishga imkon beradi.

Quyidagi jadval qaysi o'zgaruvchilar va funktsiyalar meros bo'lib o'tishini sinfni hosil qilishda berilgan ko'rinishga bog'liqligini ko'rsatadi. [10]

  • Shaxsiy →
  • Himoyalangan →
  • Ommaviy →
  • Meros emas
  • Himoyalangan
  • Ommaviy
  • Meros emas
  • Xususiy
  • Xususiy
  • Meros emas
  • Himoyalangan
  • Himoyalangan

Ikki yoki undan ortiq sinflarni bir-biri bilan birgalikda bog'lash uchun meros ishlatiladi.

Tahrirni bekor qilish

Ko'pgina ob'ektga yo'naltirilgan dasturlash tillari sinf yoki ob'ektga meros bo'lib o'tgan aspektni amalga oshirishni - odatda xatti-harakatni almashtirishga imkon beradi. Ushbu jarayon deyiladi bekor qilish. Yo'q qilish murakkablikni keltirib chiqaradi: meros qilib olingan sinfning namunasi xatti-harakatlarning qaysi versiyasidan foydalanadi - o'z sinfiga kiruvchi yoki ota-ona (tayanch) sinfidan? Javob dasturlash tillari orasida turlicha bo'lib, ba'zi tillar ma'lum bir xatti-harakatni bekor qilmaslik kerakligini va asosiy sinf tomonidan belgilab qo'yilganidek o'zini tutishi kerakligini ko'rsatib beradi. Masalan, C # da asosiy usul yoki xususiyat faqat virtual, mavhum yoki bekor modifikatori bilan belgilangan bo'lsa, subklassda bekor qilinishi mumkin, Java kabi dasturlash tillarida esa boshqa usullarni bekor qilish uchun har xil usullarni chaqirish mumkin. [11] bekor qilishning alternativasi - meros qilib olingan kodni yashirish.

Kodni qayta ishlatish Tartibga solish

Amalga oshirish merosi - bu subklass bazaviy sinfda kodni qayta ishlatadigan mexanizm. Odatiy bo'lib, subklass asosiy sinfning barcha operatsiyalarini saqlab qoladi, ammo subklass ba'zi bir yoki barcha operatsiyalarni bekor qilishi mumkin, baza-klass dasturini o'zi bilan almashtiradi.

Quyida Python-ning namunasi keltirilgan.

Ko'pgina choraklarda kodni qayta ishlatish uchun sinf merosi foydadan chetda qoldi. [ iqtibos kerak ] Asosiy muammo shundan iboratki, amalga oshirishda merosxo'rlik polimorfik o'rnini bosuvchi ishonchni ta'minlamaydi - qayta ishlatish sinfining namunasi meros qilib olingan sinfning o'rnini almashtirishi mumkin emas. Muqobil texnika, aniq delegatsiya, ko'proq dasturiy harakatlarni talab qiladi, ammo o'rnini bosish masalasidan qochadi. [ iqtibos kerak ] C ++ da xususiy meros formasi sifatida foydalanish mumkin amalga oshirish merosi o'rnini bosmasdan. Jamiyat merosi "is-a" munosabatini ifodalaydi va delegatsiya "ega-a" munosabatini ifodalaydi, xususiy (va himoyalangan) merosni "munosabatlar" nuqtai nazaridan amalga oshiriladi. [12]

Merosdan foydalanishning yana bir tez-tez ishlatilishi - bu sinflarning ma'lum bir umumiy interfeysga ega bo'lishiga kafolat berishdir, ya'ni ular bir xil usullarni qo'llashadi. Ota-onalar sinfida amalga oshiriladigan operatsiyalar va operatsiyalarning kombinatsiyasi bo'lishi mumkin. Ko'pincha, supertype va subtype o'rtasida interfeys o'zgarishi bo'lmaydi - bola ota-ona sinfining o'rniga ta'riflangan xatti-harakatni amalga oshiradi. [13]

Vorislik subtitrga o'xshaydi, lekin ulardan farq qiladi. [14] Subtitrlash berilgan turni boshqa turga yoki mavhumlashtirishga almashtirishga imkon beradi va deyiladi: is-a tilni qo'llab-quvvatlashiga qarab, yashirin yoki aniq ravishda subtip va ba'zi mavjud mavhumlik o'rtasidagi munosabatlar. Aloqani subtitr mexanizmi sifatida merosni qo'llab-quvvatlaydigan tillarda meros orqali aniq ifodalash mumkin. Masalan, quyidagi C ++ kodlari sinflar o'rtasida aniq meros munosabatini o'rnatadi B va A, qayerda B ham subklass, ham pastki turidir A, va sifatida ishlatilishi mumkin A qayerda bo'lsa ham B ko'rsatilgan (ma'lumotnoma, ko'rsatgich yoki ob'ektning o'zi orqali).

Subsipalash mexanizmi sifatida merosxo'rlikni qo'llab-quvvatlamaydigan dasturlash tillarida, asosiy sinf va hosil bo'lgan sinf o'rtasidagi munosabatlar, faqat turlar o'rtasidagi munosabatlarga nisbatan, amalga oshirishlar o'rtasidagi munosabatlardir (kodni qayta ishlatish mexanizmi). Merosxo'rlik, hattoki subtipalash mexanizmi sifatida merosni qo'llab-quvvatlaydigan dasturlash tillarida ham, xulq-atvori subtipasiga olib kelmaydi. Ota-ona kutilgan kontekstda ishlatilganda ob'ekti noto'g'ri ish tutadigan sinfni yaratish umuman mumkin, Liskovni almashtirish printsipiga qarang. [15] (Konnotatsiya / denotatsiyani taqqoslang.) Ba'zi OOP tillarida kodni qayta ishlatish va kichik tiplash tushunchalari bir-biriga to'g'ri keladi, chunki subtipni e'lon qilishning yagona usuli boshqasini amalga oshirishni meros qilib olgan yangi sinfni aniqlashdir.

Dizayn cheklovlari Tartibga solish

Dasturni loyihalashda merosdan keng foydalanish ma'lum cheklovlarni keltirib chiqaradi.

Ushbu merosxo'rlik ierarxiyasini belgilashda biz ma'lum cheklovlarni aniqladik, ularning hammasi ham kerakli emas:

Murakkab qayta ishlatish printsipi merosga alternativadir. Ushbu uslub polimorfizmni va kodni qayta ishlatishni xatti-harakatlarni boshlang'ich sinf ierarxiyasidan ajratish va har qanday biznes-domen sinfida talab qilingan o'ziga xos xatti-harakatlar sinflarini o'z ichiga oladi. Ushbu yondashuv ish vaqtidagi xatti-harakatlarning modifikatsiyasiga yo'l qo'yib, sinf iyerarxiyasining statik xususiyatidan qochadi va bir sinfga ota-bobolarining xatti-harakatlari bilan cheklanib qolmasdan, bufet uslubidagi xatti-harakatlarni amalga oshirishga imkon beradi.

Amalga oshirishning merosxo'rligi dasturchilar va ob'ektga yo'naltirilgan dasturlash nazariyotchilari o'rtasida kamida 1990 yildan beri bahsli. Ular orasida mualliflar ham bor Dizayn naqshlari, uning o'rniga interfeys merosini qo'llab-quvvatlaydigan va merosga nisbatan kompozitsiyani afzal ko'rgan. Masalan, sinflar orasidagi merosning statik xususiyatini engib o'tish uchun dekorativ naqsh (yuqorida aytib o'tilganidek) taklif qilingan. Xuddi shu muammoning yanada fundamental echimi sifatida, rolga yo'naltirilgan dasturlash aniq munosabatlarni o'rnatadi, o'ynagan, meros va kompozitsiya xususiyatlarini yangi tushunchaga birlashtirish. [ iqtibos kerak ]

Allen Xolubning so'zlariga ko'ra, amalga oshirilish merosxo'rligining asosiy muammosi shundaki, u "zaif bazaviy sinf muammosi" shaklida keraksiz bog'lanishni joriy qiladi: [5] asosiy sinfni amalga oshirishdagi o'zgartirishlar subklasslarda beparvo xulq-atvor o'zgarishiga olib kelishi mumkin. Interfeyslardan foydalanish bu muammoni oldini oladi, chunki hech qanday dastur birgalikda foydalanilmaydi, faqat API. [16] Buni ta'kidlashning yana bir usuli - "meros kapsulani buzadi". [17] Mijoz kodi tizim tomonidan ta'minlangan sinflardan meros bo'lib o'tishi va keyinchalik algoritmlarida tizim sinflari o'rnini bosishi kerak bo'lgan ramkalar kabi ochiq ob'ektga yo'naltirilgan tizimlarda muammo aniq yuzaga keladi. [5]

Xabar qilinishicha, Java ixtirochisi Jeyms Gosling, agar u Java-ni qayta tuzadigan bo'lsa, uni kiritmasligini aytib, dastur merosiga qarshi chiqdi. [16] Subtitrdan merosni ajratuvchi (interfeys merosi) 1990 yildayoq paydo bo'lgan til dizaynlari [18] bunga zamonaviy misol Go dasturlash tili.

Murakkab meros yoki etarlicha etuk bo'lmagan dizaynda ishlatiladigan meros yo-yo muammosiga olib kelishi mumkin. 1990-yillarning oxirida meros tizimdagi tuzilish kodiga asosiy yondashuv sifatida ishlatilganda, ishlab chiquvchilar tabiiy ravishda tizimning funktsional imkoniyatlari o'sib borishi bilan kodlarni bir necha meros qatlamlariga ajratishni boshladilar. Agar ishlab chiquvchilar jamoasi bir nechta meros qatlamlarini bitta javobgarlik printsipi bilan birlashtirgan bo'lsa, u juda ko'p kodlarning juda nozik qatlamlarini yaratdi, ularning ko'pchiligida har bir qatlamda faqat 1 yoki 2 qatorli kodlar bo'ladi. Jamoalar har 2-3 qatlamda murakkablikning oshishiga qarshi kodni qayta ishlatish foydasini muvozanatlashtiradigan 2 yoki 3 qatlamlarning eng maqbul sonli qatlami ekanligini yaxshi bilishdan oldin, 10 va 30 qatlamgacha meros doiralarida ishlash odatiy hol emas edi. Masalan, 30 ta qatlam qaysi disk raskadrovka kerakligini bilish uchun disk raskadrovka muammosini hal qildi. PowerBuilder asosan merosdan foydalanadigan eng yaxshi kod kutubxonalaridan birini yaratdi, u 3-4 qatlam bilan qurilgan. Meros kutubxonasidagi qatlamlar soni juda muhim va ularni 4 qatlam ostida yoki ostida saqlash kerak, aks holda kutubxona juda murakkab bo'lib, foydalanish uchun ko'p vaqt talab etadi.

Merosga oid yana bir muammo shundaki, subklasslar kodda aniqlangan bo'lishi kerak, ya'ni dastur foydalanuvchilari yangi subklasslarni qo'sha olmaydi. Boshqa dizayn naqshlari (masalan, Entity-komponent-tizim) dastur foydalanuvchilariga ish vaqtida ob'ektning o'zgarishini aniqlashga imkon beradi.


Geografik masofa metrikasi asosida xususiyatlarni tanlashning yangi algoritmi: Avstriyaning suv resurslarini oqim oqimini prognoz qilish bo'yicha amaliy ish

Ushbu maqolada turli xil stantsiyalarga ega bo'lgan katta havzalarni oqimini prognoz qilish uchun sun'iy neyron tarmog'i bilan kiritilgan o'zgaruvchan tanlov - xususiyatlarni tanlash usullariga e'tibor qaratilgan. Hozirgi gidrologiya tadqiqotlari jamiyatidagi xususiyatlarni tanlash usullari bunday havzalarda muammoni hal qilishga qodir emas. Maqola geografik masofani metrik sifatida ishlatish g'oyasiga asoslangan yangi xususiyatlarni tanlash algoritmini - Bubble Selection-ni taklif qiladi. Algoritmning ishlashini baholash Bubble Selection-ni qo'llash orqali amalga oshiriladi, bu 540 stantsiyadagi Avstriyaning suv resurslarini bitta ish rejimida modellashtirish. Maqsad har bir stantsiya uchun xususiyatlarni 2412 ta stantsiya orasidan tanlash, oqim oqimi, yog'ingarchilik, qor, qor qalinligi va suv sathining o'lchovlari mavjud. Tavsiya etilgan algoritm funktsiyalar hajmini sezilarli darajada kamaytirishga imkon beradi. Ko'pikni tanlash algoritmi ketma-ket yo'nalishni tanlash algoritmi bilan qo'shimcha ravishda birlashtiriladi. Gibrid modelning ishlash ko'rsatkichlari aniqlanish koeffitsienti, Nash-Satkliff samaradorligi va foizlarning noaniqligi bo'yicha Feature Ranking usuli ko'rsatkichlari bilan taqqoslanadi. Natijalar tavsiya etilgan gibrid algoritmning Xususiyatlar reytingidan ustunligini ko'rsatadi. Qog'oz katta havzani modellashtirish bo'yicha metodologiyani taqdim etadi va bu xususiyatlarni tanlash algoritmiga ega bo'lishi kerak bo'lgan ba'zi qobiliyatlarni ochib beradi.

Bu obuna tarkibini oldindan ko'rish, sizning muassasa orqali kirish.


Rollar

Rol a'zoga berilgan imtiyozlar to'plamini belgilaydi. Imtiyozlar a'zolarga odatiy roli yoki odatiy roli orqali beriladi. Tashkilotga qo'shilganda a'zolarga rol beriladi.

Agar sizga qanday rol tayinlanganiga amin bo'lmasangiz yoki rolingiz haqida ko'proq ma'lumotga muhtoj bo'lsangiz, "Rol haqida ma'lumot" tugmasini bosing profilingizning rol qismida.

Ro'yxatdan qo'shilgandan so'ng, ularning rolini ma'murlar va a'zolik rollarini o'zgartirish huquqiga ega bo'lganlar o'zgartirishi mumkin. Administratordan yoki administratordan rollarni o'zgartirish faqat ma'murlar tomonidan amalga oshirilishi mumkin.

Standart rollar

ArcGIS Enterprise quyidagi standart rollar uchun imtiyozlar to'plamini belgilaydi:

A'zoning foydalanuvchi turi a'zoga tayinlanishi mumkin bo'lgan standart rollarni belgilaydi. Har bir rolga mos keladigan foydalanuvchi turlari quyida keltirilgan.

  • Viewer - jamoat, tashkilot yoki a'zo bo'lgan guruh bilan baham ko'rilgan xaritalar, ilovalar, sahnalar va qatlamlar kabi narsalarni ko'rish. Tashkilotga tegishli guruhlarga qo'shiling. GeoCode manzillari yoki joy nomlari uchun Map Viewer-ga CSV, matn yoki GPX fayllarini torting. Map Viewer va ilovalarda ko'rsatmalar oling. Tomoshabin roli tayinlangan a'zolar tarkibni yarata olmaydi yoki almasha olmaydi yoki tahlil qila olmaydi. Viewer roli barcha foydalanuvchi turlariga mos keladi.
  • Ma'lumotlar muharriri - Viewer imtiyozlari va boshqa ArcGIS foydalanuvchilari tomonidan birgalikda foydalaniladigan xususiyatlarni tahrirlash qobiliyati. Ma'lumotlarni tahrirlash roli Viewer-dan tashqari barcha foydalanuvchi turlariga mos keladi.
  • Foydalanuvchi - ma'lumotlar muharriri imtiyozlari, shuningdek, guruhlar va tarkib yaratish imkoniyati. Foydalanuvchilar tashkilotning xaritalari, ilovalari, qatlamlari va vositalaridan foydalanishi va a'zolarga guruhdagi barcha narsalarni yangilashga imkon beradigan guruhlarga qo'shilishlari mumkin. Foydalanuvchi roli tayinlangan a'zolar shuningdek xaritalar va ilovalarni yaratishi, xususiyatlarini tahrirlashi, portalga narsalar qo'shishi, tarkibni almashishi va guruhlarni yaratishi mumkin. Foydalanuvchining roli Creator, GIS Professional, Storyteller va Insights Analyst foydalanuvchi turlariga mos keladi.
  • Publisher - foydalanuvchi imtiyozlari, shuningdek joylashtirilgan veb-qatlamlarni, ArcGIS Server qatlamlarini nashr etish, ma'lumotlar do'konlarini ro'yxatdan o'tkazish, ma'lumotlar do'koni elementlaridan nashr qilish, xususiyat va raster tahlillarni o'tkazish qobiliyati. Publisher roli Creator, GIS Professional, Storyteller va Insights Analyst foydalanuvchi turlariga mos keladi.
  • Administrator - noshirning imtiyozlari va tashkilotni va boshqa foydalanuvchilarni boshqarish uchun imtiyozlari.

Tashkilotda kamida bitta ma'mur bo'lishi kerak, ammo ikkitasi tavsiya etiladi. Tashkilot ichida ma'mur roliga tayinlanishi mumkin bo'lgan a'zolar sonida chegara yo'q, ammo xavfsizlik sababli siz ushbu rolni faqat unga bog'liq bo'lgan qo'shimcha imtiyozlarni talab qiladiganlarga tayinlashingiz kerak. Administrator roli Creator, GIS Professional va Insights Analyst foydalanuvchi turlariga mos keladi.

Yangi a'zolarga tayinlangan standart rolni tanlash uchun Organization & gt Settings & gt Yangi a'zolarning standart parametrlariga o'ting va "Rol" ochiladigan menyusidan rolni tanlang.

Standart foydalanuvchi turi tanlangandan keyingina siz standart rolni tanlashingiz mumkin. Faqat tanlangan standart foydalanuvchi turiga mos keladigan rollar ochiladigan menyuda ko'rsatiladi.

Quyidagi jadvalda standart rollarda mavjud bo'lgan imtiyozlar ko'rsatilgan.

Geosearch-dan foydalaning (joylar va manzillarni qidiring)

Geokod manzillari va joy nomlari

Xostlangan veb-qatlamlarni nashr etish

Serverga asoslangan qatlamlarni nashr etish

Ommaviy ma'lumotlar do'konidan nashr etish

ArcGIS daftarlarini yaratish va tahrirlash

Barcha a'zolarni, tarkibni va guruhlarni boshqaring

Veb-sayt va xavfsizlikni sozlang

Maxsus rollarni yarating va o'zgartiring

Ro'yxatdan hisoblarini o'chirish va o'chirish

Agar sayt sozlamalari a'zolarning tashkilotdan tashqarida bo'lishishiga yo'l qo'ymasa, tashkilot tarkibini jamoatchilik bilan baham ko'ring

Boshqa foydalanuvchilarning joylashuv treklarini ko'rish

Yuqorida sanab o'tilgan imtiyozlarning aksariyati odatiy rolning bir qismi sifatida ham belgilanishi mumkin, ammo ba'zi ma'muriy imtiyozlar odatiy rollarda mavjud emas, chunki ular standart administratorlar uchun saqlanadi.

Portalingiz bilan serverni birlashtirganingizda, portalning xavfsizlik do'koni serverga kirishni boshqaradi. Bu qulay kirish tajribasini ta'minlaydi, shuningdek, federatsiya serveriga qanday kirishingiz va boshqarishingizga ta'sir qiladi. Masalan, siz federatsiya qilganingizda, ArcGIS Server xizmatlarida ilgari tuzilgan barcha foydalanuvchilar, rollar va ruxsatlar endi haqiqiy emas. Xizmatlarga kirish o'rniga portal a'zolarining rollari va almashish huquqlari bilan belgilanadi. Federatsiyaning saytingizga qanday ta'sir qilishi haqida ko'proq bilish uchun federatsiya serverini boshqarish bo'limiga qarang.

Maxsus rollar

O'zingizning tashkilotingizdagi standart rollarni maxsus rollarni yaratish orqali yanada nozik imtiyozlar to'plamiga qo'shishni xohlashingiz mumkin. Masalan, sizning tashkilotingiz ba'zi a'zolarga odatiy Publisher bilan bir xil imtiyozlarni berishni xohlashi mumkin, lekin ularga GeoEnrichment-dan foydalanishga ruxsat bermasdan. Bunga standart Publisher roliga asoslangan maxsus rolni yaratish, GeoEnrichment imtiyozini o'chirish va GeoEnrichment-ga yoki boshqa shunga o'xshash narsaga Publisher-ning maxsus rolini chaqirish orqali erishish mumkin.

Faqat standart administratorlar yoki Ro'yxatdan rollari imtiyoziga ega bo'lgan maxsus ma'mur roli tayinlanganlar maxsus rollarni yaratishi va o'zgartirishi mumkin. Ushbu ma'murlar mavjud umumiy va ma'muriy imtiyozlarning har qanday kombinatsiyasi asosida maxsus rollarni sozlashi mumkin. Maxsus rol yaratilgandan so'ng, rollarni o'zgartirish imtiyoziga ega bo'lgan har qanday tashkilot a'zosi rolni a'zolarga tayinlashi mumkin.

Nashr qilishning har qanday imtiyozlariga (funktsiyalar, plitkalar yoki sahnalar uchun) ega bo'lgan maxsus rolni tayinlagan a'zo, shuningdek sizning portalingiz bilan federatsiyalangan serverlarda ArcGIS Server xizmatlarining boshqa turlarini yaratishi mumkin. Kelgusida bunday ish oqimlarini oldini olish uchun ushbu funksiyani cheklash mumkin. Agar foydalanuvchilarga ArcGIS Server xizmatlarini nashr etish imkoniyati zarur bo'lsa, ularni standart Publisher roliga qo'shish tavsiya etiladi.

Portal sozlamalarini boshqarish uchun ma'muriy imtiyozlarni o'z ichiga olgan maxsus rollarni yaratish qobiliyatiga egasiz. Bu ma'murlarga ma'lum ma'muriy vazifalar to'plamini foydalanuvchilarga standart administrator rolida ularga to'liq imtiyozlar bermasdan topshirish imkoniyatini beradi. Masalan, Tashkilot veb-saytining imtiyozlarini o'z ichiga olgan maxsus roli bo'lgan foydalanuvchi xavfsizlik yoki server sozlamalarini boshqarish kabi boshqa ma'muriy vazifalarni bajarish imkoniyatisiz portalning veb-sayt sozlamalarini boshqarish qobiliyatiga ega bo'ladi.

A'zoga maxsus rol orqali berilishi mumkin bo'lgan imtiyozlar, foydalanuvchi tomonidan tayinlangan foydalanuvchi turi bilan bog'liq imtiyozlardan oshmasligi kerak. Masalan, Viewer foydalanuvchi turiga ega bo'lgan a'zoni tahrirlash imtiyozlariga ega rolni tayinlash mumkin emas.


Maxsus pastki tarmoqlar

31-bitli subnetslar

30-bitli subnet maskasi to'rtta IPv4-manzilga imkon beradi: ikkita xost manzili, bitta nolinchi tarmoq va bitta hammaga tarqatiladigan manzil. "Nuqta-nuqta" havolasida faqat ikkita xost manzili bo'lishi mumkin. Eshittirish va barcha nol manzillarni "nuqta-nuqta" havolalari bilan bo'lishiga hojat yo'q. 31-bitli kichik tarmoq niqobi to'liq ikkita xost manziliga imkon beradi va efirga uzatiladigan va nolinchi manzillarni yo'q qiladi, shu bilan IP-manzillardan nuqta-nuqta havolalari uchun minimal foydalanishni saqlaydi.

RFC 3021-ga murojaat qiling - IPv4-dan Point-to-Point havolalarida 31-bitli prefikslardan foydalanish.

Niqob 255.255.255.254 yoki / 31.

/ 31 pastki tarmog'i ketma-ket yoki POS interfeyslari kabi haqiqiy nuqta-nuqta havolalarida ishlatilishi mumkin. Biroq, ular chekilgan interfeyslar kabi translyatsiya interfeysi turlarida ham foydalanishlari mumkin. Agar shunday bo'lsa, ushbu chekilgan segmentda faqat ikkita IPv4 manzil mavjudligiga ishonch hosil qiling.

192.168.1.0 va 192.168.1.1 192.168.1.0/31 kichik tarmog'ida.

Ogohlantirish bosilgan, chunki gigabitEthernet - bu translyatsiya segmenti.

32-bitli subnets

255.255.255.255 (a / 32 subnet) pastki tarmoq maskasi faqat bitta IPv4 xost manzili bo'lgan ichki tarmoqni tavsiflaydi. Ushbu subnetslardan tarmoq havolalariga manzil tayinlash uchun foydalanib bo'lmaydi, chunki ular uchun har doim bitta havola uchun bir nechta manzil kerak bo'ladi. / 32 dan foydalanish faqat bitta manzilga ega bo'lishi mumkin bo'lgan havolalarda foydalanish uchun qat'iy ravishda saqlanib qolgan. Cisco routerlari uchun misol loopback interfeysi. Ushbu interfeyslar ichki interfeyslar bo'lib, boshqa qurilmalarga ulanmaydi. Shunday qilib, ular / 32 pastki tarmog'iga ega bo'lishi mumkin.


Windows 10, 1607 versiyasi uchun MDM-da yangilik

Yangi yoki yangilangan maqola Tavsif
Ilovalarni yon yuklash Windows 10, 1607 versiyasidan boshlab, ilovalarni yonma-yon yuklashga faqat EnterpriseModernAppManagement CSP orqali ruxsat beriladi. Mahsulot kalitlari (5x5) endi Windows 10, 1607 versiya qurilmalarida yon yuklashni yoqish uchun qo'llab-quvvatlanmaydi.
NodeCache CSP Windows 10, 1607 versiyasida boshlangan NodeCache ildiz tugunining qiymati com.microsoft/1.0/MDM/NodeCache.
EnterpriseDataProtection CSP Yangi CSP.
CSP siyosati Quyidagi qoidalar olib tashlandi:
- DataProtection / AllowAzureRMSForEDP - ushbu siyosatni EnterpriseDataProtection CSP-ga ko'chirdi
- DataProtection / AllowUserDecryption - ushbu siyosatni EnterpriseDataProtection CSP-ga ko'chirdi
- DataProtection / EDPEnforcLevel - ushbu siyosatni EnterpriseDataProtection CSP-ga ko'chirdi
- DataProtection / RequireProtectionUnderLockConfig - ushbu siyosatni EnterpriseDataProtection CSP-ga ko'chirdi
- DataProtection / RevokeOnUnenroll - ushbu siyosatni EnterpriseDataProtection CSP-ga ko'chirdi
- DataProtection / EnterpriseCloudResources - ushbu siyosatni NetworkIsolation siyosatiga o'tkazdi
- DataProtection / EnterpriseInternalProxyServers - ushbu siyosatni NetworkIsolation siyosatiga o'tkazdi
- DataProtection / EnterpriseIPRange - ushbu siyosatni NetworkIsolation siyosatiga o'tkazdi
- DataProtection / EnterpriseNetworkDomainNames - ushbu siyosatni NetworkIsolation siyosatiga o'tkazdi
- DataProtection / EnterpriseProxyServers - ushbu siyosatni NetworkIsolation siyosatiga o'tkazdi
- Security / AllowAutomaticDeviceEncryptionForAzureADJoinedDevices - bu siyosat eskirgan.

Windows 10, 1607 versiyasi uchun WiFi / AllowManualWiFiConfiguration va WiFi / AllowWiFi qoidalari qo'shildi:
- Windows 10 Pro
- Windows 10 Enterprise
- Windows 10 Education

Quyidagi yangi qoidalar qo'shildi:
- AboveLock / AllowCortanaAboveLock
- ApplicationManagement / DisableStoreOriginatedApps
- Autentifikatsiya / AllowSecondaryAuthenticationDevice
- Bluetooth / AllowPrepairing
- Brauzer / AllowExtensions
- Browser / PreventAccessToAboutFlagsInMicrosoftEdge
- Browser / ShowMessageWhenOening OpenSitesInInternetExplorer
- DeliveryOptimization / DOAbsoluteMaxCacheSize
- DeliveryOptimization / DOMaxDownloadBandwidth
- DeliveryOptimization / DOMinBackgroundQoS
- DeliveryOptimization / DOModifyCacheDrive
- DeliveryOptimization / DOMonthlyUploadDataCap
- DeliveryOptimization / DOPercentageMaxDownloadBandwidth
- DeviceLock / EnforceLockScreenAndLogonImage
- DeviceLock / EnforceLockScreenProvider
- Defender / PUAProtektsiya
- Tajriba / AllowThirdPartySuggestionsInWindowsSpotlight
- Tajriba / AllowWindowsSpotlight
- Experience / ConfigureWindowsSpotlightOnLockScreen
- Tajriba / DoNotShowFeedbackNotifications
- Litsenziyalash / AllowWindowsEntitlementActivation
- Litsenziyalash / DisallowKMSClientOnlineAVSValidation
- LockDown / AllowEdgeSwipe
- Maps / EnableOfflineMapsAutoUpdate
- Maps / AllowOfflineMapsDownloadOverMeteredConnection
- Messaging / AllowMessageSync
- NetworkIsolation / EnterpriseCloudResources
- NetworkIsolation / EnterpriseInternalProxyServers
- NetworkIsolation / EnterpriseIPRange
- NetworkIsolation / EnterpriseIPRangesAreAuthoritative
- NetworkIsolation / EnterpriseNetworkDomainNames
- NetworkIsolation / EnterpriseProxyServers
- NetworkIsolation / EnterpriseProxyServersAreAuthoritative
- NetworkIsolation / NeutralResources
- Bildirishnomalar / DisruptNotificationMirroring
- Maxfiylik / DisableAd AdvertisingId
- Maxfiylik / LetAppsAccessAccountInfo
- Maxfiylik / LetAppsAccessAccountInfo_ForceAllowTheseApps
- Privacy/LetAppsAccessAccountInfo_ForceDenyTheseApps
- Privacy/LetAppsAccessAccountInfo_UserInControlOfTheseApps
- Privacy/LetAppsAccessCalendar
- Privacy/LetAppsAccessCalendar_ForceAllowTheseApps
- Privacy/LetAppsAccessCalendar_ForceDenyTheseApps
- Privacy/LetAppsAccessCalendar_UserInControlOfTheseApps
- Privacy/LetAppsAccessCallHistory
- Privacy/LetAppsAccessCallHistory_ForceAllowTheseApps
- Privacy/LetAppsAccessCallHistory_ForceDenyTheseApps
- Privacy/LetAppsAccessCallHistory_UserInControlOfTheseApps
- Privacy/LetAppsAccessCamera
- Privacy/LetAppsAccessCamera_ForceAllowTheseApps
- Privacy/LetAppsAccessCamera_ForceDenyTheseApps
- Privacy/LetAppsAccessCamera_UserInControlOfTheseApps
- Privacy/LetAppsAccessContacts
- Privacy/LetAppsAccessContacts_ForceAllowTheseApps
- Privacy/LetAppsAccessContacts_ForceDenyTheseApps
- Privacy/LetAppsAccessContacts_UserInControlOfTheseApps
- Privacy/LetAppsAccessEmail
- Privacy/LetAppsAccessEmail_ForceAllowTheseApps
- Privacy/LetAppsAccessEmail_ForceDenyTheseApps
- Privacy/LetAppsAccessEmail_UserInControlOfTheseApps
- Privacy/LetAppsAccessLocation
- Privacy/LetAppsAccessLocation_ForceAllowTheseApps
- Privacy/LetAppsAccessLocation_ForceDenyTheseApps
- Privacy/LetAppsAccessLocation_UserInControlOfTheseApps
- Privacy/LetAppsAccessMessaging
- Privacy/LetAppsAccessMessaging_ForceAllowTheseApps
- Privacy/LetAppsAccessMessaging_ForceDenyTheseApps
- Privacy/LetAppsAccessMessaging_UserInControlOfTheseApps
- Privacy/LetAppsAccessMicrophone
- Privacy/LetAppsAccessMicrophone_ForceAllowTheseApps
- Privacy/LetAppsAccessMicrophone_ForceDenyTheseApps
- Privacy/LetAppsAccessMicrophone_UserInControlOfTheseApps
- Privacy/LetAppsAccessMotion
- Privacy/LetAppsAccessMotion_ForceAllowTheseApps
- Privacy/LetAppsAccessMotion_ForceDenyTheseApps
- Privacy/LetAppsAccessMotion_UserInControlOfTheseApps
- Privacy/LetAppsAccessNotifications
- Privacy/LetAppsAccessNotifications_ForceAllowTheseApps
- Privacy/LetAppsAccessNotifications_ForceDenyTheseApps
- Privacy/LetAppsAccessNotifications_UserInControlOfTheseApps
- Privacy/LetAppsAccessPhone
- Privacy/LetAppsAccessPhone_ForceAllowTheseApps
- Privacy/LetAppsAccessPhone_ForceDenyTheseApps
- Privacy/LetAppsAccessPhone_UserInControlOfTheseApps
- Privacy/LetAppsAccessRadios
- Privacy/LetAppsAccessRadios_ForceAllowTheseApps
- Privacy/LetAppsAccessRadios_ForceDenyTheseApps
- Privacy/LetAppsAccessRadios_UserInControlOfTheseApps
- Privacy/LetAppsAccessTrustedDevices
- Privacy/LetAppsAccessTrustedDevices_ForceAllowTheseApps
- Privacy/LetAppsAccessTrustedDevices_ForceDenyTheseApps
- Privacy/LetAppsAccessTrustedDevices_UserInControlOfTheseApps
- Privacy/LetAppsSyncWithDevices
- Privacy/LetAppsSyncWithDevices_ForceAllowTheseApps
- Privacy/LetAppsSyncWithDevices_ForceDenyTheseApps
- Privacy/LetAppsSyncWithDevices_UserInControlOfTheseApps
- Security/PreventAutomaticDeviceEncryptionForAzureADJoinedDevices
- Settings/AllowEditDeviceName
- Speech/AllowSpeechModelUpdate
- System/TelemetryProxy
- Update/ActiveHoursStart
- Update/ActiveHoursEnd
- Update/AllowMUUpdateService
- Update/BranchReadinessLevel
- Update/DeferFeatureUpdatesPeriodInDays
- Update/DeferQualityUpdatesPeriodInDays
- Update/ExcludeWUDriversInQualityUpdate
- Update/PauseFeatureUpdates
- Update/PauseQualityUpdates
- Update/SetProxyBehaviorForUpdateDetection
- Update/UpdateServiceUrlAlternate (Added in the January service release of Windows 10, version 1607)
- WindowsInkWorkspace/AllowWindowsInkWorkspace
- WindowsInkWorkspace/AllowSuggestedAppsInWindowsInkWorkspace
- WirelessDisplay/AllowProjectionToPC
- WirelessDisplay/RequirePinForPairing

Updated the Privacy/AllowAutoAcceptPairingAndPrivacyConsentPrompts description to remove outdated information.

Updated DeliveryOptimization/DODownloadMode to add new values.

Updated Experience/AllowCortana description to clarify what each supported value does.

Added the new 1.3 version of the DDF.


Create New Feature Class Based off Multiple Feature Classes - Geographic Information Systems

Reference: Sommerville, Software Engineering, 10 ed., Chapter 15

In most engineering disciplines, systems are designed by composing existing components that have been used in other systems. Software engineering has been more focused on original development but it is now recognized that to achieve better software, more quickly and at lower cost, we need a design process that is based on systematic software reuse. There has been a major switch to reuse-based development over the past 10 years.

  • System reuse: Complete systems, which may include several application programs.
  • Application reuse: An application may be reused either by incorporating it without change into other or by developing application families.
  • Component reuse: Components of an application from sub-systems to single objects may be reused.
  • Object and function reuse: Small-scale software components that implement a single well-defined object or function may be reused.
  • Accelerated development: Bringing a system to market as early as possible is often more important than overall development costs. Reusing software can speed up system production because both development and validation time may be reduced.
  • Effective use of specialists: Instead of doing the same work over and over again, application specialists can develop reusable software that encapsulates their knowledge.
  • Increased dependability: Reused software, which has been tried and tested in working systems, should be more dependable than new software. Its design and implementation faults should have been found and fixed.
  • Lower development costs: Development costs are proportional to the size of the software being developed. Reusing software means that fewer lines of code have to be written.
  • Reduced process risk: The cost of existing software is already known, whereas the costs of development are always a matter of judgment. This is an important factor for project management because it reduces the margin of error in project cost estimation. This is particularly true when relatively large software components such as subsystems are reused.
  • Standards compliance: Some standards, such as user interface standards, can be implemented as a set of reusable components. For example, if menus in a user interface are implemented using reusable components, all applications present the same menu formats to users. The use of standard user interfaces improves dependability because users make fewer mistakes when presented with a familiar interface.
  • Creating, maintaining, and using a component library: Populating a reusable component library and ensuring the software developers can use this library can be expensive. Development processes have to be adapted to ensure that the library is used.
  • Finding, understanding, and adapting reusable components: Software components have to be discovered in a library, understood and, sometimes, adapted to work in a new environment. Engineers must be reasonably confident of finding a component in the library before they include a component search as part of their normal development process.
  • Increased maintenance costs: If the source code of a reused software system or component is not available then maintenance costs may be higher because the reused elements of the system may become increasingly incompatible with system changes.
  • Lack of tool support: Some software tools do not support development with reuse. It may be difficult or impossible to integrate these tools with a component library system. The software process assumed by these tools may not take reuse into account. This is particularly true for tools that support embedded systems engineering, less so for object-oriented development tools.
  • Not-invented-here syndrome: Some software engineers prefer to rewrite components because they believe they can improve on them. This is partly to do with trust and partly to do with the fact that writing original software is seen as more challenging than reusing other people's software.

Although reuse is often simply thought of as the reuse of system components, there are many different approaches to reuse that may be used. Reuse is possible at a range of levels from simple functions to complete application systems. The reuse landscape covers the range of possible reuse techniques.

  • The development schedule for the software.
  • The expected software lifetime.
  • The background, skills and experience of the development team.
  • The criticality of the software and its non-functional requirements.
  • The application domain.
  • The execution platform for the software.

Frameworks are moderately large entities that can be reused. They are somewhere between system and component reuse. Frameworks are a sub-system design made up of a collection of abstract and concrete classes and the interfaces between them. The sub-system is implemented by adding components to fill in parts of the design and by instantiating the abstract classes in the framework.

Application frameworks are moderately large entities that can be reused. They are somewhere between system and component reuse. Frameworks are a sub-system design made up of a collection of abstract and concrete classes and the interfaces between them. The sub-system is implemented by adding components to fill in parts of the design and by instantiating the abstract classes in the framework.

Web application frameworks (WAF) support the construction of dynamic websites as a front-end for web applications. WAFs are now available for all of the commonly used web programming languages e.g. Java, Python, Ruby, etc. Interaction model is based on the Model-View-Controller composite design pattern. An MVC framework supports the presentation of data in different ways and allows interaction with each of these presentations. When the data is modified through one of the presentations, the system model is changed and the controllers associated with each view update their presentation.

  • Security: WAFs may include classes to help implement user authentication (login) and access.
  • Dynamic web pages: Classes are provided to help you define web page templates and to populate these dynamically from the system database.
  • Database support: The framework may provide classes that provide an abstract interface to different databases.
  • Session management: Classes to create and manage sessions (a number of interactions with the system by a user) are usually part of a WAF.
  • User interaction: Most web frameworks now provide AJAX support, which allows more interactive web pages to be created.

Frameworks are generic and are extended to create a more specific application or sub-system. They provide a skeleton architecture for the system. Extending the framework involves Adding concrete classes that inherit operations from abstract classes in the framework Adding methods that are called in response to events that are recognized by the framework. Problem with frameworks is their complexity which means that it takes a long time to use them effectively.

  • Component and system configuration
  • Adding new components to the system
  • Selecting from a library of existing components
  • Modifying components to meet new requirements.
  • Core components that provide infrastructure support. These are not usually modified when developing a new instance of the product line.
  • Configurable components that may be modified and configured to specialize them to a new application. Sometimes, it is possible to reconfigure these components without changing their code by using a built-in component configuration language.
  • Specialized, domain-specific components some or all of which may be replaced when a new instance of a product line is created.
  • Application frameworks rely on object-oriented features such as polymorphism to implement extensions. Product lines need not be object-oriented (e.g. embedded software for a mobile phone)
  • Application frameworks focus on providing technical rather than domain-specific support. Product lines embed domain and platform information.
  • Product lines often control applications for equipment.
  • Software product lines are made up of a family of applications, usually owned by the same organization.

Product line architectures must be structured in such a way to separate different sub-systems and to allow them to be modified. The architecture should also separate entities and their descriptions and the higher levels in the system access entities through descriptions rather than directly.

  • Different versions of the application are developed for different platforms.
  • Different versions of the application are created to handle different operating environments masalan. different types of communication equipment.
  • Different versions of the application are created for customers with different functional requirements.
  • Different versions of the application are created to support different business processes.
  • Design time configuration: The organization that is developing the software modifies a common product line core by developing, selecting or adapting components to create a new system for a customer.
  • Deployment time configuration: A generic system is designed for configuration by a customer or consultants working with the customer. Knowledge of the customer's specific requirements and the system's operating environment is embedded in configuration data that are used by the generic system.

An application system product is a software system that can be adapted for different customers without changing the source code of the system. Application systems have generic features and so can be used/reused in different environments. Application system products are adapted by using built-in configuration mechanisms that allow the functionality of the system to be tailored to specific customer needs.

  • As with other types of reuse, more rapid deployment of a reliable system may be possible.
  • It is possible to see what functionality is provided by the applications and so it is easier to judge whether or not they are likely to be suitable.
  • Some development risks are avoided by using existing software. However, this approach has its own risks, as I discuss below.
  • Businesses can focus on their core activity without having to devote a lot of resources to IT systems development.
  • As operating platforms evolve, technology updates may be simplified as these are the responsibility of the COTS product vendor rather than the customer.
  • Requirements usually have to be adapted to reflect the functionality and mode of operation of the COTS product.
  • The COTS product may be based on assumptions that are practically impossible to change.
  • Choosing the right COTS system for an enterprise can be a difficult process, especially as many COTS products are not well documented.
  • There may be a lack of local expertise to support systems development.
  • The COTS product vendor controls system support and evolution.

Configurable application systems are generic application systems that may be designed to support a particular business type, business activity or, sometimes, a complete business enterprise. For example, an application system may be produced for dentists that handles appointments, dental records, patient recall, etc. Domain-specific systems, such as systems to support a business function (e.g. document management) provide functionality that is likely to be required by a range of potential users.

An Enterprise Resource Planning (ERP) system is a generic system that supports common business processes such as ordering and invoicing, manufacturing, etc. These are very widely used in large companies - they represent probably the most common form of software reuse. The generic core is adapted by including modules and by incorporating knowledge of business processes and rules. A number of modules to support different business functions. A defined set of business processes, associated with each module, which relate to activities in that module. A common database that maintains information about all related business functions. A set of business rules that apply to all data in the database.

  • A number of modules to support different business functions.
  • A defined set of business processes, associated with each module, which relate to activities in that module.
  • A common database that maintains information about all related business functions.
  • A set of business rules that apply to all data in the database.
  • Selecting the required functionality from the system.
  • Establishing a data model that defines how the organization's data will be structured in the system database.
  • Defining business rules that apply to that data.
  • Defining the expected interactions with external systems.
  • Designing the input forms and the output reports generated by the system.
  • Designing new business processes that conform to the underlying process model supported by the system.
  • Setting parameters that define how the system is deployed on its underlying platform.

Integrated application systems

  • Which individual application systems offer the most appropriate functionality? Typically, there will be several application system products available, which can be combined in different ways.
  • How will data be exchanged? Different products normally use unique data structures and formats. You have to write adaptors that convert from one representation to another.
  • What features of a product will actually be used? Individual application systems may include more functionality than you need and functionality may be duplicated across different products.

Application system integration can be simplified if a service-oriented approach is used. A service-oriented approach means allowing access to the application system's functionality through a standard service interface, with a service for each discrete unit of functionality. Some applications may offer a service interface but, sometimes, this service interface has to be implemented by the system integrator. You have to program a wrapper that hides the application and provides externally visible services.


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