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comparison: netwerk/protocol/http/README
netwerk/protocol/http/README
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- TOR_BUG_9701
- changeset 15
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| -1:000000000000 | 0:49be089585b1 |
|---|---|
| 1 Darin Fisher | |
| 2 darin@netscape.com | |
| 3 8/8/2001 | |
| 4 | |
| 5 HTTP DESIGN NOTES | |
| 6 | |
| 7 | |
| 8 CLASS BREAKDOWN | |
| 9 | |
| 10 nsHttpHandler | |
| 11 - implements nsIProtocolHandler | |
| 12 - manages preferences | |
| 13 - owns the authentication cache | |
| 14 - holds references to frequently used services | |
| 15 | |
| 16 nsHttpChannel | |
| 17 - implements nsIHttpChannel | |
| 18 - talks to the cache | |
| 19 - initiates http transactions | |
| 20 - processes http response codes | |
| 21 - intercepts progress notifications | |
| 22 | |
| 23 nsHttpConnection | |
| 24 - implements nsIStreamListener & nsIStreamProvider | |
| 25 - talks to the socket transport service | |
| 26 - feeds data to its transaction object | |
| 27 - routes progress notifications | |
| 28 | |
| 29 nsHttpConnectionInfo | |
| 30 - identifies a connection | |
| 31 | |
| 32 nsHttpTransaction | |
| 33 - implements nsIRequest | |
| 34 - encapsulates a http request and response | |
| 35 - parses incoming data | |
| 36 | |
| 37 nsHttpChunkedDecoder | |
| 38 - owned by a transaction | |
| 39 - removes chunked decoding | |
| 40 | |
| 41 nsHttpRequestHead | |
| 42 - owns a nsHttpHeaderArray | |
| 43 - knows how to fill a request buffer | |
| 44 | |
| 45 nsHttpResponseHead | |
| 46 - owns a nsHttpHeaderArray | |
| 47 - knows how to parse response lines | |
| 48 - performs common header manipulations/calculations | |
| 49 | |
| 50 nsHttpHeaderArray | |
| 51 - stores http "<header>:<value>" pairs | |
| 52 | |
| 53 nsHttpAuthCache | |
| 54 - stores authentication credentials for http auth domains | |
| 55 | |
| 56 nsHttpBasicAuth | |
| 57 - implements nsIHttpAuthenticator | |
| 58 - generates BASIC auth credentials from user:pass | |
| 59 | |
| 60 | |
| 61 ATOMS | |
| 62 | |
| 63 nsHttp:: (header namespace) | |
| 64 | |
| 65 eg. nsHttp::Content_Length | |
| 66 | |
| 67 | |
| 68 TRANSACTION MODEL | |
| 69 | |
| 70 InitiateTransaction -> ActivateConnection -> AsyncWrite, AsyncRead | |
| 71 | |
| 72 The channel creates transactions, and passes them to the handler via | |
| 73 InitiateTransaction along with a nsHttpConnectionInfo object | |
| 74 identifying the requested connection. The handler either dispatches | |
| 75 the transaction immediately or queues it up to be dispatched later, | |
| 76 depending on whether or not the limit on the number of connections | |
| 77 to the requested server has been reached. Once the transaction can | |
| 78 be run, the handler looks for an idle connection or creates a new | |
| 79 connection, and then (re)activates the connection, assigning it the | |
| 80 new transaction. | |
| 81 | |
| 82 Once activated the connection ensures that it has a socket transport, | |
| 83 and then calls AsyncWrite and AsyncRead on the socket transport. This | |
| 84 begins the process of talking to the server. To minimize buffering, | |
| 85 socket transport thread-proxying is completely disabled (using the flags | |
| 86 DONT_PROXY_LISTENER | DONT_PROXY_PROVIDER | DONT_PROXY_OBSERVER with | |
| 87 both AsyncWrite and AsyncRead). This means that the nsHttpConnection's | |
| 88 OnStartRequest, OnDataAvailable, OnDataWritable, and OnStopRequest | |
| 89 methods will execute on the socket transport thread. | |
| 90 | |
| 91 The transaction defines (non-virtual) OnDataReadable, OnDataWritable, and | |
| 92 OnStopTransaction methods, which the connection calls in response to | |
| 93 its OnDataAvailable, OnDataWritable, and OnStopRequest methods, respectively. | |
| 94 The transaction owns a nsStreamListenerProxy created by the channel, which | |
| 95 it uses to transfer data from the socket thread over to the client's thread. | |
| 96 To mimize buffering, the transaction implements nsIInputStream, and passes | |
| 97 itself to the stream listener proxy's OnDataAvailable. In this way, we | |
| 98 have effectively wedged the response parsing between the socket and the | |
| 99 thread proxy's buffer. When read, the transaction turns around and reads | |
| 100 from the socket using the buffer passed to it. The transaction scans the | |
| 101 buffer for headers, removes them as they are detected, and copies the headers | |
| 102 into its nsHttpResponseHead object. The rest of the data remains in the | |
| 103 buffer, and is proxied over to the client's thread to be handled first by the | |
| 104 http channel and eventually by the client. | |
| 105 | |
| 106 There are several other major design factors, including: | |
| 107 | |
| 108 - transaction cancelation | |
| 109 - progress notification | |
| 110 - SSL tunneling | |
| 111 - chunked decoding | |
| 112 - thread safety | |
| 113 - premature EOF detection and transaction restarting | |
| 114 - pipelining (not yet implemented) | |
| 115 | |
| 116 | |
| 117 CACHING | |
| 118 | |
| 119 <EOF> |
