HTTP/2 を読み解く技術

HTTP2.0 勉強会 #3での発表資料。

Transcript

1. )551ΛಡΈղٕ͘ज़
   

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2. Moto Ishizawa
   (@summerwind)
   1/27
   

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3. http://summerwind.jp/docs/draft-ietf-httpbis-http2-09/
   2/27
   

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4. )551ͷ࢓༷ॻΛಡΈղͨ͘Ίʹඞ
   ཁͳ஌ࣝ΍ٕज़Λ঺հ͠·͢ɻ
   3/27
   

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5. ωοτϫʔΫؔ࿈
   

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6. HTTP/1.1 pipelining only partially
   addressed request concurrency and suffers
   from head-of-line blocking.
   “
   ”
   ― 1. Introduction
   5/27
   

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7. Head-of-line Blocking (HoL Blocking)
   σʔλΛૹ৴͢ΔΩϡʔ
   Data #1
   Data #2
   Data #3
   Data #4
   Data #5
   ૹ৴ʹࣦഊ͠
   ࠶ૹ͕ඞཁͳσʔλ
   ૹ৴଴ͪͷσʔλͨͪ
   )P-#MPDLJOH
   
   6/27
   

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8. Head-of-line Blocking (HoL Blocking)
   Client Server
   HTTP/1.1 pipelining
   ΋͠࠷ॳͷϨεϙϯεͷॲཧʹ
   ͕͔͔࣌ؒͬͨ৔߹ɺ2ͭ໨Ҏ߱ͷ
   Ϩεϙϯε΋ͦΕʹҾ͖ͣΒΕΔ
   (HoL Blocking)
   ϦΫΤετͷૹ৴
   Ϩεϙϯεͷૹ৴
   7/27
   

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9. Flow control is used for both individual
   streams and for the connection as a whole.
   “
   ”
   ― 5.2. Flow Control
   8/27
   

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10. Flow control
    9/27
    σʔλͷ௨৴࣌ʹɺड৴ଆͷॲཧ͕௥͍͔ͭͣʹσʔλͷ
    औΓ͜΅͕͠ൃੜ͢ΔͷΛ๷͙ͨΊɺঢ়گʹԠͯ͡ૹ৴ଆ
    ͕σʔλͷૹ৴Λఀࢭͨ͠Γɺૹ৴ྔΛௐ੔ͨ͠Γ͢Δͨ
    Ίͷ࢓૊Έɻ
    !
    ௨৴ͷ։࢝࣌ʹड৴ଆ͕΢Πϯυ΢αΠζͱݺ͹ΕΔҰ౓
    ʹड৴Մೳͳ༰ྔΛૹ৴ଆʹ௨஌͠ɺૹ৴ଆ͸ͦͷαΠζ
    ʹैͬͯૹ৴ྔΛ੍ޚ (΢Πϯυ΢੍ޚ) ͢Δɻ
    

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11. Flow control
    Client
    53όΠτड৴ͨ͠ͷͰ
    ࢒Γ͸47όΠτ
    53όΠτૹ৴
    47όΠτૹ৴
    47όΠτड৴ͨ͠ͷͰ
    ࢒Γ͸0όΠτ
    ΢Πϯυ΢͕100όΠτ
    Ͱ͋Δ͜ͱΛ௨஌
    Server
    ߹ܭͰ100όΠτૹ৴
    ͨ͠ͷͰҰ࣌ૹ৴ఀࢭ
    89όΠτॲཧͨ͠ͷͰ
    89όΠτ·Ͱ͸ૹ৴
    Մೳͳ͜ͱΛ఻͑Δ
    ૹ৴Λ࠶։
    89όΠτૹ৴
    10/27
    

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12. Flow control (HTTP/2)
    Client
    ίωΫγϣϯͷ΢Πϯυ΢͸࢒Γ65,482όΠτ
    ετϦʔϜID: 1ͷ΢Πϯυ΢͸࢒Γ47όΠτ
    ετϦʔϜID: 1ʹ53όΠτૹ৴
    ετϦʔϜID: 1ʹ47όΠτૹ৴
    ίωΫγϣϯͷ΢Πϯυ΢͸࢒Γ65,435όΠτ
    ετϦʔϜID: 1ͷ΢Πϯυ΢͸࢒Γ0όΠτ
    SETTINGSϑϨʔϜͷ
    SETTINGS_INITIAL_WINDOW_SIZEͰετϦʔϜ
    ͷ΢Πϯυ΢͕100όΠτͰ͋Δ͜ͱΛ௨஌
    (ίωΫγϣϯͷ΢Πϯυ΢͸65,535όΠτݻఆ)
    Server
    89όΠτΛॲཧͨ͠ͷͰɺετϦʔϜID: 1ʹ
    WINDOW_UPDATEϑϨʔϜΛૹ৴ͯ͠ɺ
    ετϦʔϜID: 1ͷ΢Πϯυ΢Λ89όΠτʹ͢Δ
    ετϦʔϜID: 1ʹ89όΠτૹ৴
    11/27
    

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13. Note, however, that this can lead to
    suboptimal use of available network
    resources if flow control is enabled without
    knowledge of the bandwidth-delay product.
    “
    ”
    ― 5.2.2. Appropriate Use of Flow Control
    12/27
    

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14. Bandwidth-delay product (BDP)
    ωοτϫʔΫଳҬ෯ × σʔλͷԟ෮஗Ԇ࣌ؒ
    ωοτϫʔΫ্ʹྲྀ͢͜ͱ͕Ͱ͖Δ࠷దͳσʔλͷྔΛࣔ͢ɻ
    ΢Πϯυ΢αΠζͷ࠷ద஋ΛٻΊΔͨΊʹ࢖༻͢Δ஋ɻ
    13/27
    

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15. Bandwidth-delay product (BDP)
    ྫ: RTT͕100ms͔͔Δ10MbpsͷճઢͷBDPΛܭࢉ͢Δɻ
    10Mbps = 10,000,000bit/s = 1,221KB/s
    100ms = 0.1s
    1,221KB/s × 0.1s = 122.1KB
    ͜ͷ஋͔Βɺ΢Πϯυ΢αΠζ͸࠷௿Ͱ΋122.1KB͕ඞཁɻ
    BDPͷ஋Λ΋ͱʹ΢Πϯυ΢αΠζͷνϡʔχϯάΛ͓͜ͳ͏ɻ
    14/27
    

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16. 5-4ؔ࿈
    

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17. A client that makes a request to an "https"
    URI without prior knowledge about support
    for HTTP/2.0 uses TLS with the application
    layer protocol negotiation extension.
    “
    ”
    ― 3.3. Starting HTTP/2.0 for "https" URIs
    16/27
    

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18. Application Layer Protocol Negotiation (ALPN)
    Client Server
    TLS Handshake
    ClientHello
    ServerHello
    ALPN Extension
    HTTP/1
    HTTP/2
    SPDY/3
    ALPN Extension
    Selected protocol
    HTTP/2
    17/27
    

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19. Application Layer Protocol Negotiation (ALPN)
    https://github.com/http2/http2-spec/wiki/ALPN-Status
    18/27
    

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20. )551Yؔ࿈
    

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21. The 1xx series of HTTP response status codes
    are not supported in HTTP/2.0.
    “
    ”
    ― 8.1.1. Informational Responses
    20/27
    

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22. The 1xx Series of HTTP response status codes
    100 Continue
    ϦΫΤετϔομΛड৴ͨ͠αʔόʔ͕ɺϦΫΤετϘςΟͷ
    ड৴͕Մೳͳ͜ͱΛ஌ΒͤΔͨΊͷεςʔλείʔυɻ
    !
    101 Switching Protocols
    ௨৴ʹ࢖༻͢ΔϓϩτίϧΛ HTTP ͔Βଞͷϓϩτίϧʹ
    ੾Γସ͑ΔͨΊʹ࢖༻͢Δεςʔλείʔυɻ
    21/27
    

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23. Client Server
    100 Continue
    ϦΫΤετ
    100 Continue
    POST /search HTTP/1.1
    Expect: 100-continue
    ৘ใఏڙϨεϙϯε
    ϦΫΤετϘσΟ
    Ϩεϙϯε
    The 1xx Series of HTTP response status codes
    22/27
    

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24. In HTTP/2.0, the CONNECT method is used to
    establish a tunnel over a single HTTP/2.0
    stream to a remote host.
    “
    ”
    ― 8.3. The CONNECT Method
    23/27
    

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25. CONNECT (HTTP/1.1)
    Client Proxy Server
    ϦΫΤετ
    CONNECT example.com:80 HTTP/1.1
    Host: example.com:80
    Ϩεϙϯε
    200 Connection Established
    αʔόʔʹର͢ΔϦΫΤετ
    GET /index.html HTTP/1.1
    தܧ͞ΕͨϦΫΤετ
    GET /index.html HTTP/1.1
    ઀ଓ
    24/27
    

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26. CONNECT (HTTP/2)
    Client Proxy Server
    HEADERS ϑϨʔϜ
    :method : CONNECT
    :authority : example.com:80
    HEADERS ϑϨʔϜ
    :status : 200
    DATA ϑϨʔϜ
    GET /index.html HTTP/1.1
    ϦΫΤετ
    GET /index.html HTTP/1.1
    ઀ଓ
    25/27
    

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27. http://bit.ly/browser-networking
    26/27
    

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28. Enjoy HTTP/2 ;-)
    

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