[英]ZeroMQ send/receive on PHP works if script launched from CLI/shell but not from APACHE/web request
I'm testing ZeroMQ for PHP.我正在为 PHP 测试 ZeroMQ。 My goal is to send messages to a Python script.
我的目标是将消息发送到 Python 脚本。 Everything works fine if i launch my transmission script from PHP cli
如果我从 PHP cli 启动传输脚本,一切正常
php /path/to/myscript.php
while it fails if it's a web request.如果它是 web 请求,则会失败。 I've tried executing the server script from PHP cli as above (which seems to be the more logical way) and with a web request.
我已经尝试从上面的 PHP cli 执行服务器脚本(这似乎是更合乎逻辑的方式)并使用 web 请求。
I've got a Centos 7 server with PHP 7.2 and ZeroMQ 1.1.3 installed through PECL install.我通过 PECL 安装安装了 PHP 7.2 和 ZeroMQ 1.1.3 的 Centos 7 服务器。
I even tried launching the above command with shell_exec/exec inside the client script but it doesn't work.我什至尝试在客户端脚本中使用 shell_exec/exec 启动上述命令,但它不起作用。 Connection works fine, but it doesn't send nor receive.
连接工作正常,但它不发送也不接收。
Client code:客户端代码:
$context = new ZMQContext();
// Socket to talk to server
echo "Connecting to hello world server...\n";
$requester = new ZMQSocket($context, ZMQ::SOCKET_REQ);
$currentObject = $requester->connect("tcp://localhost:5555");
for ($request_nbr = 0; $request_nbr != 10; $request_nbr++) {
printf ("Sending request %d...\n", $request_nbr);
$risSend = $requester->send("Hello", ZMQ::MODE_NOBLOCK);
print_r($risSend);
$reply = $requester->recv();
printf ("Received reply %d: [%s]\n", $request_nbr, $reply);
}
Server Code:服务器代码:
$context = new ZMQContext(1);
// Socket to talk to clients
$responder = new ZMQSocket($context, ZMQ::SOCKET_REP);
$responder->bind("tcp://*:5555");
while (true) {
// Wait for next request from client
$request = $responder->recv();
printf ("Received request: [%s]\n", $request);
// Send reply back to client
$responder->send("World");
}
The browser gets stuck, without any error.浏览器卡住了,没有任何错误。 Even using a timeout it reaches the limit and exits but I can't get any error message.
即使使用超时,它也会达到限制并退出,但我无法收到任何错误消息。
OBSERVATION : The browser gets stuck, without any error.
观察:浏览器卡住了,没有任何错误。
This is pretty legal state.这是非常合法的 state。 For it to happen, it is quite enough to "miss" the arrival of the first
REQ
-side-already dispatched request and due to a pleasure do depend on a distributed-Finite-State-Automaton, we fall into an unsalvageable dead-lock, where the REQ
-side waits for an answer, that will never arrive (see next) and the REP
-side waits for a request, that will never arrive (see the REQ
-side already waiting ) and such a state remains forever that.为了让它发生,“错过”第一个
REQ
端已经发送的请求的到来就足够了,并且由于很高兴确实依赖于分布式有限状态自动机,我们陷入了无法挽救的死锁,其中REQ
端等待一个永远不会到达的答案(参见下一个),而REP
端等待一个永远不会到达的请求(参见REQ
端已经在等待),这样的 state 永远保持不变。
A best next step:最好的下一步:
In case one has never worked with ZeroMQ,如果从未使用过 ZeroMQ,
or have never met the concept of the art of Zen-of-Zero ,或者从来没有遇到过零之禅的艺术概念,
one may here enjoy to first look at "ZeroMQ Principles in less than Five Seconds " before diving into further details在深入了解更多细节之前,您可能会喜欢先看看“ZeroMQ原则在不到 5 秒内”
Start开始
with unconditionally working archetypes - a pair of PUSH / PULL
simplex-channels, that do not require a dFSA-two-step of REQ-REP-REQ-REP-REQ-REP-...-{deadlock}
... a principally unavoidable terminal state, about which one is just never sure when it happens, but it will... at some later time:o)具有无条件工作的原型 - 一对
PUSH / PULL
单纯形通道,不需要REQ-REP-REQ-REP-REQ-REP-...-{deadlock}
的 dFSA 两步...不可避免的终端 state,关于哪一个永远不确定它何时会发生,但它会......在以后的某个时间:o)
Next,下一个,
may increase a robustness of the message-flow, using zmq_setsockopt( ZMQ_IMMEDIATE, 1 )
that avoids moving messages onto incomplete connections between / among peers.可以使用
zmq_setsockopt( ZMQ_IMMEDIATE, 1 )
来增加消息流的稳健性,以避免将消息移动到对等点之间的不完整连接上。
Always总是
prefer non-blocking forms of .recv()
-methods, best with a pre-test of a message-presence with a .poll()
-method.更喜欢
.recv()
方法的非阻塞 forms,最好使用.poll()
方法对消息存在进行预测试。 Poller
-class, while available in many language-bindings is not always as handy and as flexible as using explicit .poll()
-method directly on a Socket
-instance. Poller
类虽然在许多语言绑定中都可用,但并不总是像直接在Socket
实例上使用显式.poll()
方法那样方便和灵活。
Also feel free to read more about fine-tuning the ZeroMQ tools and other implications of the Art of the Zen-of-Zero here .也可以随意阅读更多关于微调 ZeroMQ 工具和零之艺术的其他含义的信息。
A Server-side mock-up: As a { PASS |服务器端模型:作为 { PASS | FAIL }-proof of
.send()---.recv()
-delivery chain works? FAIL } -
.send()---.recv()
链有效吗?
<?php /* Create new PUSH-ing end */
$aCTX = new ZMQContext();
try { /* Try: things may turn wreck havoc */
$PUSHer = $aCTX->getSocket(, ZMQ::SOCKET_PUSH );
echo "POSACK'd: .getSocket() was made\n";
}
catch ( ZMQSocketException $e ){
echo " NACK'd: I told you ...\n"; /* Handle with care ... */
if ( $e->getCode() === ZMQ::ERR_... ) {
echo " - Got ERR_..., read ZeroMQ API documentation for details\n";
} else {
die( " - Get ERR: " . $e->getMessage() );
}
}
try { /* Try: things may turn wreck havoc */
$PUSHer->bind( "tcp://A.B.C.D:NNN" ); /* IP address to .connect() */
echo "POSACK'd: .bind() was made\n";
}
catch ( ZMQSocketException $e ){
echo " NACK'd: I told you ...\n"; /* Handle with care ... */
if ( $e->getCode() === ZMQ::ERR_... ) {
echo " - Got ERR_..., read ZeroMQ API documentation for details\n";
} else {
die( " - Get ERR: " . $e->getMessage() );
}
}
$retries = 1234567;
do { /* Start a loop */
try { /* Try: to PUSH.send() */
echo "Trying to send a message #" . ( 1234568 - $retries ) . "\n";
$PUSHer->send( "This is a message", ZMQ::MODE_DONTWAIT );
echo "POSACK'd: PUSHer.send() was made\n";
}
} catch ( ZMQSocketException $e ) {
echo " NACK'd: I told you ...\n"; /* Handle with care ... */
if ( $e->getCode() === ZMQ::ERR_... ) {
echo " - Got ERR_..., read ZeroMQ API documentation for details\n";
} else { /* For all ERR_... states */
die( " - Got ERR_...: " . $e->getMessage() );
}
}
/* --------------------------------------------------------------------
Here one may add an attempt to .recv( $PULLer, ZMQ::MODE_DONTWAIT );
and test for a non-empty string returned
-------------------------------------------------------------------- */
usleep( 1 ); /* Sleep a bit between operations */
} while ( --$retries );
?>
Client-side mock-up , to test the PUSH-er lives and .send()
-s客户端模型,用于测试 PUSH-er 生命和
.send()
-s
import time, datetime, zmq; print( "Thissssss Sssssssssssssssssssssssssssssssssssssssnake uses ZeroMQ ver:{0:}".format( zmq.__version__ ) )
aCtx = zmq.Context()
aPull= aCtx.Socket( zmq.PULL )
aPull.setsockopt( zmq.LINGER, 0 ) # always ... be explicit
aPull_address2c = "tcp://A.B.C.D:NNN"
M0 = "{0:} try a .connect( {1:} ), if it gets to PUSH-er side"
M1 = "{0:} try a .recv(), if it gets any message"
M2 = "{0:} got a .recv()->[[[ {1:} ]]]"
M3 = "{0:} EXC'd will gracefully release resources and terminate..."
M4 = "{0:} did"
try:
print( M0.format( datetime.datetime.isoformat( datetime.datetime.now() ),
aPull_address2c
)
)
aPull.connect( aPull_address2c );
while True:
print( M1.format( datetime.datetime.isoformat( datetime.datetime.now() ) )
m = aPull.recv( zmq.NOBLOCK ) # always ... avoid blocking waits
if ( len( m ) > 0 ):
print( M2.format( datetime.datetime.isoformat( datetime.datetime.now() ),
str( m ) # always ... fused to str()
)
)
time.sleep( 5 )
else:
time.sleep( 1 )
pass
################################################################
# Here one may add an attempt to aPush.send( M4, zmq.NOBLOCK )
# and test if the reverse path aPush->$PULLer goes well
################################################################
except:
print( M3.format( datetime.datetime.isoformat( datetime.datetime.now() ) )
finally:
aPull.close() # always ... be explicit
aCtx.term() # always ... be explicit
print( M4.format( datetime.datetime.isoformat( datetime.datetime.now() ) )
Ok, i finally found the solution.好的,我终于找到了解决方案。 Thanks to @user3666197 i managed to get an error.
感谢@user3666197,我设法得到了一个错误。 And it was a "permission denied" error.
这是一个“权限被拒绝”错误。
With CentOS (and probably all linux sytems with SELinux) you gotta add a rule for the port used by ZMQ for the webserver .使用 CentOS(可能还有所有带有 SELinux 的 linux 系统),您必须为 ZMQ用于 webserver的端口添加一条规则。
Example:例子:
semanage port -a -t http_port_t -p tcp 5555
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