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[英]Are the chunk sizes in an HTTP response with “Transfer-Encoding: chunked”, significant to protocols that sit on top of HTTP?
[英]HTTP/1.1 - Transfer-Encoding: chunked - delay in the middle of response
我正在使用WINC1500 WiFi(與Arduino一起)連接到服務器(https)並發送一些API請求。 在標題中,我發送:
POST /api/myapi.php HTTP/1.1
Host: myserver.com
Accept: application/json, text/javascript, */*; q=0.01
Content-Type: application/x-www-form-urlencoded; charset=iso-8859-1
Connection: keep-alive
Content-Length: 10
my_content
服務器響應正常,如下所示:
HTTP/1.1 200 OK
Date: Tue, 03 Sep 2019 16:31:14 GMT
Server: Apache
Expires: Thu, 19 Nov 1981 08:52:00 GMT
Cache-Control: no-store, no-cache, must-revalidate
Pragma: no-cache
Keep-Alive: timeout=5, max=100
Connection: Keep-Alive
Transfer-Encoding: chunked
Content-Type: application/json
18f
BlaBlaBla.... (399 chars = 18f in hexa)
0
問題在於,在第一個塊之后,等待終止塊會有延遲。 最后一塊是空的。 這是一個了解它的示例 :
HTTP/1.1 200 OK
Content-Type: text/plain
Transfer-Encoding: chunked
7\r\n
Mozilla\r\n
9\r\n
Developer\r\n
7\r\n
Network\r\n
0\r\n
\r\n
好吧...讓我們看一下時間線:
19:31:13.685 -> connecting...
19:31:14.325 -> posting...
19:31:15.745 -> end posting...
19:31:15.864 -> HTTP/1.1 200 OK
19:31:15.864 -> Date: Tue, 03 Sep 2019 16:31:14 GMT
19:31:15.864 -> Server: Apache
19:31:15.864 -> Expires: Thu, 19 Nov 1981 08:52:00 GMT
19:31:15.864 -> Cache-Control: no-store, no-cache, must-revalidate
19:31:15.864 -> Pragma: no-cache
19:31:15.904 -> Keep-Alive: timeout=5, max=100
19:31:15.904 -> Connection: Keep-Alive
19:31:15.904 -> Transfer-Encoding: chunked
19:31:15.904 -> Content-Type: application/json
19:31:15.904 ->
19:31:15.904 -> waitingChunkLength: 18f
19:31:15.904 -> 399
19:31:15.945 -> waitingChunk: BlaBlaBla.... (399 chars)
19:31:20.875 -> waitingChunkLength: 0
19:31:20.875 -> 0
19:31:20.875 -> waitingChunkTrailer:
19:31:20.875 -> Done...
Connection closed
在收到第一個也是唯一的塊之后,在接收最后一個(終止)塊之前會有很大的延遲。 實際上,最后一塊在服務器關閉連接之前發送。 我相信這是由於空閑時間而發生的。 有5秒鍾的不活動時間,因此服務器必須關閉連接。
我嘗試在收到第一個塊后立即向服務器發送消息(“確定”)。 在這種情況下,服務器會立即做出響應,但是正在關閉連接(我相信是由於消息不足):
19:45:43.818 -> connecting...
19:45:44.688 -> posting...
19:45:46.207 -> end posting...
19:45:46.322 -> HTTP/1.1 200 OK
19:45:46.322 -> Date: Tue, 03 Sep 2019 16:45:44 GMT
19:45:46.322 -> Server: Apache
19:45:46.322 -> Expires: Thu, 19 Nov 1981 08:52:00 GMT
19:45:46.322 -> Cache-Control: no-store, no-cache, must-revalidate
19:45:46.322 -> Pragma: no-cache
19:45:46.322 -> Keep-Alive: timeout=5, max=100
19:45:46.358 -> Connection: Keep-Alive
19:45:46.358 -> Transfer-Encoding: chunked
19:45:46.358 -> Content-Type: application/json
19:45:46.358 ->
19:45:46.358 ->
19:45:46.358 -> waitingChunkLength: 18f
19:45:46.358 -> 399
19:45:46.398 -> waitingChunk: BlaBlaBla.... (399 chars)
19:45:46.517 -> waitingChunkLength: 0
19:45:46.517 -> 0
19:45:46.517 -> waitingChunkTrailer:
19:45:46.517 -> Done...
Connection closed
我需要知道問題出在哪里。 我應該在每個塊之后向服務器發送特殊消息嗎? 由於這種行為,我無法利用“保持活動”會話。
在幾次修改固件后都沒有成功之后,我回到代碼中嘗試不同的方法。 問題似乎是POST操作的最后一行:
client.print("Content-Length: ");
client.println(10);
client.println();
client.println("my_content");
最后一行應該是:
client.print("my_content");
... println
在文本后附加回車符(ASCII 13或'\\ r')和換行符(ASCII 10或'\\ n')。 因此,這些額外的(意外)字符給我帶來了很多麻煩。 希望這也能解決您的問題。
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