RSS - eto format, prednazna4enniy dla publikacii novostey na novostnix i podobnix im saytax, na4inaa ot takix vedu6ix novostnix saytov, kak Wired, Slashdot, i kon4aa li4nimi setevimi dnevnikami (weblog-ami). No po suti, publikovat' mojno ne tol'ko novosti. Prakti4eski luboy material, kotoriy mojno razdelit' na otdel'nie 4asti, mojno publikovat' s pomo6'u RSS: naprimer, ob&avlenia o poslednix publikaciax v "wiki", informacia ob obnovleniax v CVS, istoria izmeneniy, vnesennix v knigu. Posle togo, kak informacia preobrazovana v format RSS, programma, ponimau6aa etot format, mojet vitagivat' svedenia o vnesennix izmeneniax i v zavisimosti ot rezul'tata, naprimer, avtomati4eski predprinimat' kakie-libo deystvia.
Programmi, umeu6ie rabotat' s RSS, nazivautsa agregatorami, i oni o4en' popularni sredi ludey, vedu6ix setevie dnevniki (weblog-i). Nekotorie programmi-dnevniki daje pozvolaut drugim delat' kommentarii k zapisam. I mnogie dnevniki umeut publikovat' zapisi v formate RSS. Programma-agregator pozvolaet vam sobirat' vse eti publikacii vmeste, i vi polu4aete vozmojnost' odnovremenno sledit' za poavleniem novix novostey na vsex saytax srazu i 4itat' ix kratkoe soderjanie, ne pose6aa kajdiy sayt v otdel'nosti.
Kratkaa istoria
Programmisti, bud'te bditel'ni! Pod terminom "RSS" skrivaetsa format, kotoriy raspalsa na neskol'ko razli4nix versiy kak minimum dvux razli4nix (no su6estvuu6ix odnovremenno) formatov. Isxodniy RSS, versiu 0.90, razrabotali v kompanii Netscape. Eto bil format, prednazna4enniy dla sozdania novostnix portalov vedu6ix novostnix kompaniy. Tak kak mnogie pos4itali ego sli6kom slojnim, kompania Netscape razrabotala bolee prostuu versiu - 0.91, kotoruu, vpro4em, zabrosila, poterav vsakiy interes k biznesu portalov. No versia 0.91 bila peredana na poruki kompanii UserLand Software, kotoraa sobiraetsa ispol'zovat' etot format kak osnovu dla svoix weblog-produktov i drugix web-prilojeniy.
Tem vremenem, tret'a, uje nekommer4eskaa organizacia, otkolov6is' ot ob6ego te4enia, sozdala noviy format, kotoriy, kak polagalos', sootvetstvuet duxu i principam isxodnogo formata RSS 0.90 (t.e. do togo, kak on bil upro6en do 0.91). Etot format, osnovanniy na azike RDF, nazvali RSS 1.0. K sojaleniu, kompania UserLand ne prinimala u4astia v razrabotke etogo novogo formata, i kak za6itnik upro6ennoy versii 0.90 ona ne bila s4astliva, kogda poavilsa format RSS 1.0. Vmesto prinatia etogo formata UserLand re6ila razvit' vetku 0.9x i sozdala versii 0.92, potom 0.93, 0.94 i nakonec 2.0.
Vot takoy vinegret.
Tak kakim je formatom mne pol'zovat'sa?
Itak, su6estvuet 7 - tol'ko podumayte "7!" - razli4nix formatov, i vse oni nazivautsa RSS. Kak programmistu, pi6u6emu programmu-agregator, vam pridetsa srajat'sa so vsemi etimi formatami. Nu a kakoy format vibrat' pol'zovatelu, publikuu6emu svoi novosti v formate RSS?
Versii RSS i rekomendacii
Versia
Vladelec
Za
Status
Soveti
0.90
Netscape
Otmenen versiey 1.0
Ne pol'zuytes'
0.91
UserLand
O4en'-o4en' prostoy
Oficial'no otmenen vixodom versii 2.0. No vse e6e popularen
Pol'zuytes' dla prostix publikaciy. Esli vam ponadobitsa bol'6ee, vi legko smojete pereyti na 2.0
0.92, 0.93, 0.94
UserLand
Bol'6e vozmojnostey, 4em u 0.91
Otmenen s vixodom versii 2.0
Pol'zuytes' versiey 2.0
1.0
RSS-DEV Working Group
Osnovan na azike RDF. Ras6iraetsa s pomo6'u moduley. Ne zavisit ot kakoy-libo odnoy kompanii
Stabilen. Vedetsa aktivnaa razrabotka moduley
Ispol'zuyte dla prilojeniy, gde ispol'zuetsa RDF, libo v tom slu4ae, esli vam nujen kakoy-to opredelenniy modul'
2.0
UserLand
Ras6iraetsa s pomo6'u moduley. Prost pri migracii s vetki formatov 0.9x
Stabilen. Vedetsa aktivnaa razrabotka moduley
Ispol'zuyte dla publikacii novostey ob6ego nazna4enia
Kak vigladit RSS?
Skajem, vi zaxoteli napisat' programmu, kotoraa s4itivaet novosti v formate RSS, 4tobi, naprimer, publikovat' zagolovki novostey na svoem sayte, ili 4tobi sozdat' portal novostey i tak dalee. Kak vigladit RSS-fayl? Vse zavisit ot togo, o kakoy versii RSS idet re4'. Vot primer fayla v formate RSS 0.91 (urezannaa versia novostey s www.xml.com):
http://www.xml.com/ XML.com features a rich mix of information and services for the XML community. en-us
http://www.xml.com/pub/a/2002/12/04/normalizing.html In this second and final look at applying relational normalization techniques to W3C XML Schema data modeling, Will Provost discusses when not to normalize, the scope of uniqueness and the fourth and fifth normal forms.
http://www.xml.com/pub/a/2002/12/04/som.html Priya Lakshminarayanan describes in detail the use of the .NET Schema Object Model for programmatic manipulation of W3C XML Schemas.
http://www.xml.com/pub/a/2002/12/04/svg.html In this month"s SVG column, Antoine Quint looks back at SVG"s journey through 2002 and looks forward to 2003.
Vse prosto, pravda? Blok novostey (channel) sostoit iz zagolovka, ssilki, dannix o azike novostey i opisania. Posle etogo idet spisok samix novostey, gde v kajdom punkte ukazivaetsa zagolovok, ssilka i kratkoe opisanie novosti.
Teper' davayte vzglanem, kak ta je samaa informacia vigladit v formate RSS 1.0:
http://www.xml.com/ XML.com features a rich mix of information and services for the XML community. en-us
http://www.xml.com/pub/a/2002/12/04/normalizing.html In this second and final look at applying relational normalization techniques to W3C XML Schema data modeling, Will Provost discusses when not to normalize, the scope of uniqueness and the fourth and fifth normal forms. Will Provost 2002-12-04
http://www.xml.com/pub/a/2002/12/04/som.html Priya Lakshminarayanan describes in detail the use of the .NET Schema Object Model for programmatic manipulation of W3C XML Schemas. Priya Lakshminarayanan 2002-12-04
http://www.xml.com/pub/a/2002/12/04/svg.html In this month"s SVG column, Antoine Quint looks back at SVG"s journey through 2002 and looks forward to 2003. Antoine Quint 2002-12-04
Dovol'no mnogoslovno, ne tak li? Te, kto znakom s RDF, srazu uznaut, 4to etot fayl - RDF-dokument, soxranenniy v XML. Ostal'nie, razberutsa, 4to v fayle predstavlena vsa ta je informacia, 4to i v pervom primere. Mi tol'ko dobavili e6e nekotoruu dopolnitel'nuu informaciu, kak, naprimer, avtorstvo kajdoy novosti, i datu publikacii, kotorix net v RSS 0.91.
Nesmotra na to, 4to RSS 1.0 avlaetsa smes'u RDF i XML, strukturno on sxoj s predidu6imi versiami RSS - sxoj dostato4no, 4tobi mi rassmatrivali ego kak obi4niy XML-fayl. Sledovatel'no mi mojem napisat' odnu programmu, kotoraa umeet izvlekat' informaciu iz oboix formatov: i iz RSS 0.91 i iz RSS 1.0. Odnako est' vse-taki nekotorie razli4ia, o kotorix va6a programma doljna znat':
Kornevim elementom v RSS 1.0 avlaetsa rdf:RDF, a ne rss. Vam libo pridetsa avno obrabativat' oba etix elementa, libo prosto ignorirovat' ix i slepo izvlekat' tol'ko tu informaciu, kotoraa vam nujna.
V RSS 1.0 ispol'zuutsa prostranstva imen (namespaces). Prostranstvo imen dla RSS 1.0 vigladit tak http://purl.org/rss/1.0/. I eto prostranstvo imen prinimaetsa po umol4aniu. Krome togo v fayle ispol'zuutsa prostranstva imen http://www.w3.org/1999/02/22-rdf-syntax-ns# dla elementov, specifi4nix dla RDF (mi ix toje mojem ignorirovat'), i http://purl.org/dc/elements/1.1/ (Dublin Core) dla dopolnitel'nix metadannix ob avtorax statey i datax publikaciy.
Vi mojete poyti dvuma putami: esli va6 XML-parser ne ponimaet prostranstva imen, vi mojete prosto s4itat', 4to v fayle ispol'zuutsa elementi s prefiksami i slepo iskat' v nix elementi items i dc:creator. Takoy sposob srabotaet v bol'6instve slu4aev, tak kak v novostax formata RSS 1.0 4a6e vsego ispol'zuetsa tol'ko prostranstvo imen, prinatoe po umol4aniu, i prostranstvo imёn Dublin Core. Kone4no, danniy sposob - ne eleganten, ved' net nikakix garantiy, 4to v kakix-nibud' novostax ne budet ispol'zovano kakoe-libo drugoe prostranstvo imen (4to vpolne legal'no s to4ki zrenia RDF i XML). I va6 parser propustit vse novosti.
Esli je va6 XML-parser ponimaet prostranstva imen, vi mojete postroit' bolee iza6noe re6enie, kotoroe sumeet razobrat' novosti i formate 0.91 i v formate 1.0.
Menee o4evidniy, no vajniy fakt sostoit v tom, 4to v RSS 1.0 elementi item naxodatsa vne elementa channel. V RSS 0.91 elementi item raspolojeni vnutri channel. V 0.90 oni bili snaruji. V 2.0 - oni vnutri. Vo-kak! Ne zaputaytes' s tem, v kakom elemente nado iskat' novosti.
Nakonec, vi zametite, 4to v elemente channel est' odin element items. On nujen tol'ko dla RDF-parserov (zadaet poradok novostey). Vi mojete ego ignorirovat' i s4itat', 4to vse novosti idut v tom poradke, v kakom raspolojeni elementi item.
A kak vigladit format RSS 2.0? K s4ast'u, dla programm, ponimau6ix formati RSS 0.91 i 1.0, format RSS 2.0 budet pro6e parenoy repi.
http://www.xml.com/ XML.com features a rich mix of information and services for the XML community. en-us
http://www.xml.com/pub/a/2002/12/04/normalizing.html In this second and final look at applying relational normalization techniques to W3C XML Schema data modeling, Will Provost discusses when not to normalize, the scope of uniqueness and the fourth and fifth normal forms. Will Provost 2002-12-04
http://www.xml.com/pub/a/2002/12/04/som.html Priya Lakshminarayanan describes in detail the use of the .NET Schema Object Model for programmatic manipulation of W3C XML Schemas. Priya Lakshminarayanan 2002-12-04
http://www.xml.com/pub/a/2002/12/04/svg.html In this month"s SVG column, Antoine Quint looks back at SVG"s journey through 2002 and looks forward to 2003. Antoine Quint 2002-12-04
Kak pokazivaet danniy primer, v RSS 2.0 toje ispol'zuutsa prostranstva imen, kak i v RSS 1.0. No eto ne RDF. Kak i v RSS 0.91, net prostranstva imen, prinatogo po umol4aniu, a novosti (v elementax item) razme6eni opat' v elemente channel.
What is RSS? avtor: 2002 (c) Mark Pilgrim i XML.com perevod: Aleksandr Ka4anov
