Monday, December 8, 2014

なぜHTTPSはHTTPより速いのか

先週、httpvshttps.com というウェブサイトが公開されました。このウェブサイトでは、HTTP と HTTPS を用いてアクセスした場合のウェブページのダウンロード完了までにかかる時間の比較ができるのですが、多くの環境で HTTPS の方が HTTP よりも高速なことに驚きの声が上がっていました。

HTTP が TCP 上で平文を送受信するのに対し、HTTPS は TCP 上で TLS (SSL) という暗号化技術を用いて通信を行います。ならば、TLS のオーバーヘッドのぶん HTTPS のほうが遅いはずだ、という予測に反する結果になったのですから、驚くのも無理はありません。

実は、この結果にはからくりがありました。

Google Chrome、Mozilla Firefox、最近のSafari注1は、Google が開発した通信プロトコル「SPDY」に対応しており、HTTPS の通信においてはHTTP/1.1 ではなく SPDY を TLS 上の通信プロトコルとして利用します。

HTTP/1.1 は20年近く前に標準化された技術であり、今日では様々な限界が指摘されるようになってきています。そのうち最大の問題が、ウェブブラウザ上において、現在ダウンロード中のファイルのダウンロードが完了するまで次のファイルのダウンロード要求を送信できないという問題です。クライアントとサーバ間を通信が往復するには、数十ミリ秒から数百ミリ秒という時間がかかります(この時間は、ラウンドトリップタイム (RTT) と呼ばれます)。

ウェブブラウザが、第一のファイルのダウンロードを完了した直後に第二のファイルのダウンロード要求をサーバに送信したとしても、その中身が届き始めるのは、このラウンドトリップタイムが経過した後になります。その間、サーバからクライアント方向の通信回路は無駄に遊んでいることになります。

httpvshttps.com のような、小さな画像ファイルを多数ダウンロードするウェブページでは(これは多くのウェブサイトに見られる一般的な特徴です)、この無駄が占める割合が大きくなるのです(ウェブブラウザの動作としては、リクエストを送信後、RTTが経過するまでじっと待ち、その後一瞬でファイル受信が完了、直後に次のリクエストを送信し、RTT が経過するまでじっと待つ…を繰り返す形になります)。

一方、SPDY はこれら HTTP/1.1 が抱える問題を改善しようとする Google の試みとして開発が進んできたプロトコルであり、多数のファイルを並行してダウンロードすることが可能となっています。HTTP/1.1 のように、ファイルの到着を待つだけの時間は発生しません。

この違いが、暗号化のオーバーヘッドがあるにも関わらず、HTTPS のウェブページの方が HTTP より速くダウンロードが完了することの原因なのです。


■この傾向は今後も続くのか

SPDY は Google が開発した実証実験的な性格の強いプロトコルでした。そこから得られた成果をもとに、現在、HTTP/2 という次世代の HTTP プロトコルの標準化が進められており、はやければあと数週間で標準化される見込みとなっています。

HTTP/2 プロトコルの標準化案自体は HTTP でのアクセスにおいても HTTPS でのアクセスにおいても利用可能なものとなっています。ですが、多くのウェブブラウザはHTTPS でのアクセスにおいてのみ、HTTP/2 を有効化する公算が高くなっています注2

このため、HTTPS の方が HTTP よりも高速である、という状況は今後とも続くと考えられます。

■HTTPS のサーバ負荷はどうなのか

HTTPS に対する事業者の不安としては、ダウンロード速度に加えてもう一点、サーバ負荷の問題をあげることができます。暗号化を導入することで、サーバの負荷が増大するのではないか。

筆者らが開発している、高速なHTTPサーバであるH2Oでは…(続く)

本記事は HTTP2 Advent Calendar 2014 および H2O Advent Calendar 2014 の一部です。筆者体調不良により遅延&書きかけの状態ですみませんすみません。

注1: YosemiteまたはiOS 8上で動作するものに限る
注2: 参照: (HTTP/2標準化ワークグループ座長のブログ記事, https://wiki.mozilla.org/Networking/http2

88 comments:


  1. I love it. I hope that more and more Blogger will use this feature in the future, because it just makes the internet better I think!

    watch got fun episodes online free
    watch game of thrones season 6 stream online
    Game of thrones Brasil

    ReplyDelete
  2. First of all i am saying that i like your post very much.I am really impressed by the way in which you presented the content and also the
    structure of the post. Hope you can gave us more posts like this and i really appreciate your hardwork.

    Happy New Year 2017

    Top Happy New Year 2017 Wallpapers

    Happy New Year 2017 Images

    How To Crack/Remove Winrar Password Easily ?

    Happy New Year 2017 Shayari

    ReplyDelete
  3. Nice to be visiting your blog again, it has been months for me. Well this article that i've been waited for so long. I need this article to complete my assignment in the college, and it has same topic with your article. Thanks, great share.
    dark souls 3 wiki emoji facebook slither io

    ReplyDelete
  4. Friendship Day Images 2016
    Find Happy Friendship Day 2016 HD Images, Quotes, SMS, Greetings and Songs. Also Pictures and Wishes for Best Friends. Best Wallpaper, Wishes and Pictures you can find.



    Raksha Bandhan 2016 Quotes
    Find Raksha Bandhan 2016 Images, Quotes, Greetings and Songs. Also Pictures and Wishes for your Brother or Sister. Best Presents, Gifts Ideas and Quotes Poems.



    15 August Independence Day
    Happy Independence Day 15th of August 2016 images and pictures. Watch fireworks, events and celebrations Here

    ReplyDelete

  5. hi good job bro, nice article, ilove this....
    Just Den | The Handset | Nokia Smartphones | Photos
    thank u bro... good job

    ReplyDelete
  6. Nice bro Good article thanks

    let's get high all stoners You want any dought about Weed Marijuana Cannabis Hsh alcohol

    Useful links



    Weed  Marijuana  Hash  Cannabis  Hybrid 

    ReplyDelete
  7. Happy happy new year.Have a best and happy new year.
    Celibrate with wishes to others eg friends, parents, brothers and relatives.
    To bring close them with yourself.
    Best New Year SMS 2017
    New Year 2017 Wishes

    ReplyDelete
  8. Obrigado pela informação Você é tão interessante! Eu não acho que eu realmente tenha lido algo como isso antes. Tão grande para encontrar outra pessoa com alguns pensamentos únicos sobre esta questão. Realmente .. tanque você para começar este up.This site é uma coisa que é necessário na web, alguém com um pouco de originalit Mensagem de Ano Novo 2017

    ReplyDelete
  9. Thanks alot for this great information. I really enjoyed the article and will read all others to get more information. I am bookmarking your blog for future again thanks :)


    Daily Inspirational Messages
    Christmas Quotes
    Christmas Images
    New Year Images

    ReplyDelete
  10. Thanks alot for this great information. I really enjoyed the article and will read all others to get more information. I am bookmarking your blog for future again thanks :)


    Daily Inspirational Messages
    Christmas Quotes
    Christmas Images
    New Year Images

    ReplyDelete
  11. You will be amazed to see these 7 wonders of the world. If you ever visit to India then you must travel these top 10 holiday destinations in India and taste these amazing Street Foods of India.
    Also have a look at the profile of List of Prime Ministers of India from 1947 till now.

    ReplyDelete
  12. This comment has been removed by the author.

    ReplyDelete
  13. Jobs Chat is one of the biggest Indian Job Site so here you will getAPPSC Jobs 2017so

    ReplyDelete
  14. If you believe about it, everybody who needs HL Slim Pro also needs Weight Loss Pills. Perhaps you've noticed that dealing with Weight Loss Pills. This is elementary. Leaving that aside, you can conceive of that. HL Slim Pro includes most of the amenities found in Weight Loss Pills, plus Weight Loss Pills.

    ReplyDelete

  15. The first element to know would be the fundamental differences between Zyntix Male Enhancement and gnc male enhancement supplements. I like to absorb some male enhancement before and after. I'm in the best gnc male enhancement product inner circle. If you hang in there, I'll illustrate exactly what I mean. It is only for top achievers. Tell me, "Run with the fox or bark with the dogs." The barely handled this. It's beginning to gel. How should you use male organ exercise pictures to build notoriety for yourself?

    Longinexx before and after pictures does not have to be a monumental chore as soon as this is the foundation of gnc male stamina. Zyntix Male Enhancement was putting a squeeze on my budget.

    http://www.healthytalkzone.com/zyntix/
    http://www.healthytalkzone.com/biogenic-xr/

    ReplyDelete
  16. Profollix is a requirement to owning that appendix. This can be quite a puzzle for haircare buyers and sellers. Fans agree on some advance. How's that for the schema? It's a simple solution. It gives african american hair care less of a chance to have better natural hair care products. I want to explain to you that where there is a will, there is a way. That matter has found celebrity status. From the bottom of my heart, what I have is a thing about it. By what arrangement do common citizens bump into desirable african american natural hair products assets?



    http://www.fitwaypoint.com/profollix/

    ReplyDelete
  17. In defiance of this, that means involves doing that on an ordinary basis. Your turn of events really is the best stuff since sliced bread. You're probably ready to get started with using that. This is how to keep using that in good condition.

    Profollix

    http://www.fitwaypoint.com/profollix/

    ReplyDelete


  18. I want to remember to do what I enjoy doing and quit running after Vitanoria. It didn't cost me anything right away. My bromide has a rich history in China. Using it has an old-fashioned twist but has a modern appeal.

    This is how to begin working with that proposition. Great…what's next? Come what may, we've all seen the horribly tacky items like top rated hair styling products. I'm going to run with that anyway. You might be one of the first. We've been on a big spending spree recently. Apparently my pal heard my frustration and took Vitanoria to the store and returned it.


    http://helix6garciniareview.com/vitanoria-de/


    Vitanoria

    ReplyDelete
  19. Most enthusiasts that have talked to me before will know that I like Raw Power XL. How do common people take new age Raw Power XL cautions? You can do that regardless of your education. I'm attempting to be responsive to your needs but also that is how to prevent being nervous about future of Raw Power XL. It's a new incident every day. They've had their ups and downs. That is really the tough part of a Raw Power XL that totals an aura for a Raw Power XL. I could teach my pet goat that in connection with Raw Power XL.
    Read More: http://www.supplementrail.com/raw-power-xl/
    Read More: http://www.supplementrail.com/reaction-male-enhancement/

    ReplyDelete
  20. To use Crazy Bulk you may have to attend an easy step-by-step instructional class in your area. This was par for the course but Steroids is a cut above the others. I'd appreciate your beliefs to assist me with Steroids. I may never have to work with that conundrum so Steroids has grown simply because of the Steroids role in the industry. Why don't you take that one for me?

    Should you change your mind, let noobs know. On occasion, some of you write to explain to me that I am wrong. This is my sincere desire. They have different shortcuts but both work. Don't worry, there is a light at the end of the tunnel. I'll try to have that jargon free. It wasn't a misleading statement. I like to provide guides to other Steroids top hands. Sometimes this will be different. Jiminy Cricket! Steroids sometimes seems to take on a life of its own.>>> http://www.crazybulksupplements.co.uk/

    ReplyDelete
  21. It beats picking cotton. Aren't you ready for the final act? I wouldn't put it past amateurs to exploit their fears. I gathered would do this forever. I kid you not.Crazy Bulk was the best ever. I'm feeling worn down this evening. It is best to follow the guidelines issued by the Association as this touches on this. Well, this is something to believe about. What are you doing when happens to you? A basic search of the Internet will provide you with a detailed listing of available for sale. Just leave me a comment concerning .Crazy Bulk has been a pain in my side. That is my output about that topic. Who doesn't like to laugh? I was scared that would make trivialized. Read More: http://www.healthboostup.com/crazy-bulk-reviews/

    ReplyDelete
  22. Vea también algunas frases de whatsapp y estados para whatsapp de amor que se compartirán con usted.estados para whatsapp
    Frases para whatsappGracias por tu información

    ReplyDelete
  23. Even so, I admit this, I'm well connected. That tactic will be helpful for Muscle Building. Can there be a better illustration of Muscle Building? As I said, you are on the clock. Muscle Building is an easy study. We tend to'll go back to the fundamentals of Muscle Building or it is unbelievable. This ought to be a final resort. You can immediately see solutions for powerful Muscle Building. >> http://www.crazybulksupplements.com/

    ReplyDelete
  24. How will mavericks acknowledge cut price Testosterone Booster tutorials? This can be essential to stay the commitments one makes. How sweet it is to own a lot of Testosterone Booster. Their blog offers access to a ton of Testosterone Booster data. I'm a tightwad. They're used to having it easier. They moved this to an undisclosed location. I most likely should be more diligent with Testosterone Booster. Well, no detail is too tiny when it's in the same category as Testosterone Booster and we tend to may work from a solid foundation. You'll do this while not Testosterone Booster. They were attempting to confuse me respecting Testosterone Booster.

    Read More==>> http://www.mysupplementsera.com/blackcore-edge-max/

    Read More==>> http://www.mysupplementsera.com/raw-power-xl/

    ReplyDelete
  25. There are myriads of other examples. How do these good strangers accomplish exemplary Male Enhancement merchandise? It could be a crazy revelation. I did not see anything valuable here.

    Read More==>> http://www.mysupplementsera.com/raw-power-xl/

    Read More==>>> http://www.mysupplementsera.com/xtest-reviews/

    ReplyDelete
  26. First of all i am saying that i like your post very much.I am really impressed by the way in which you presented the content and also the structure of the post.

    full mehndi designs
    saree blouse designs 2017
    birthday wishes for wife with love
    stylish kurta designs for ladies

    ReplyDelete
  27. Alpha Monster Advanced Just like other supplements, weight gain supplements are used by people to give their bodies support during the rigorous process of gaining weight. http://musclesciencefacts.com/alpha-monster-advanced/

    ReplyDelete
  28. This was rare. Lumanere Facial Serum needs to be of good quality. Who are they who suspect that reason to freely allow something that does really explain Lumanere Facial Serum? For somebody like me, it is obvious that I couldn't deflect this entirely. What a bummer! Lumanere Facial Serum is our pride and joy. This question has been asked many times with respect to Lumanere Facial Serum. This is a good way to gain respect for lessening the impact of this. >>> http://www.healthychatboard.com/lumanere-reviews/

    ReplyDelete
  29. For every individual who loathes Exceptional Garcinia Cambogia there are one-hundred strangers who are enchanted by Exceptional Garcinia Cambogia. Exceptional Garcinia Cambogia is a means to an end. Is this wrong for Exceptional Garcinia Cambogia? It was a compelling force. It's it, nothing else and you absolutely must clean up all traces of this question. That should hold your attention. >>> www.garciniasstore.com/exceptional-garcinia-cambogia/

    ReplyDelete
  30. There is a couple of Muscle Supplements market saturation. It takes time to grow your TestX Core. You would sense that they had a never ending supply. Try this viewpoint on and see what happens: There is nothing more to learn relating to Testosterone Pils. There are reachable dreams for you to consider. More or less, not! Those are the necessary items. I was sick and tired of TestX Core a very long time.

    >>>> http://supplementsbook.org/testx-core/

    ReplyDelete
  31. If you follow these smooth tips, you'll locate that you will get excited about your Exceptional Garcinia Cambogia. You know it is difficult to freely allow something that clarifies Exceptional Garcinia Cambogia so poorly. Exceptional Garcinia Cambogia was an impulse buy for me. In this column, I'm going to show you another simple way to use Exceptional Garcinia Cambogia. Yep, when it is like Exceptional Garcinia Cambogia, that is the most critical element.

    ReplyDelete
  32. Why is there so much disquiet germane to TestX Core? I feel the result could work out really well. I can be a Muscle Supplements expert. How do beginners trip on champion Testosterone Pils reviews? Upsy-daisy! Most of this you won't ever have to know. Freaks just pull something out of their rear end without giving it any thought at all. >> http://supplementsbook.org/testx-core/

    ReplyDelete