i am making a program that sends data between a server program and its clients. They all use the server and client socket components found in Delphi! I have looked on the Internet and cannot find a way on how to measure how much data has been transferred through a socket!
Any help, especially some code (pascal/Delphi), would be very much appreciated!
here you have a full example http://delphi.about.com/od/fullcodeprojects/l/aa112903a.htm
If you use win/*nix API sockets (not a special libraries) you have to count returns from recv and send functions.
total_data = 0;
...
...
get_data = recv(...)
total_data = total_data + get_data
...
send_data = send(...)
total_data = total_data + send_data
Magenta Systems has a free set of components that can monitor network traffic using either raw sockets or WinPcap.
Update:
From your comment to RBA's response: The Magenta components let you identify and differentiate between different IP addresses and services (ports).
I keep stats on all my TCP traffic to the byte. Every time I send data I update the stats and every time I receieve data I update the stats. This is accurate to one byte and requires only a few lines of code. And it does not rely on any particular TCP components. Why is doing it this way so hard?
Related
I have a ROS node that allows you to "publish" a data structure to it, to which it responds by publishing an output. The timestamp of what I published and what it publishes is matched.
Is there a mechanism for a blocking function where I send/publish and output, and it waits until I receive an output?
I think you need the ROS_Services (client/server) pattern instead of the publisher/subscriber.
Here is a simple example to do that in Python:
Client code snippet:
import rospy
from test_service.srv import MySrvFile
rospy.wait_for_service('a_topic')
try:
send_hi = rospy.ServiceProxy('a_topic', MySrvFile)
print('Client: Hi, do you hear me?')
resp = send_hi('Hi, do you hear me?')
print("Server: {}".format(resp.response))
except rospy.ServiceException, e:
print("Service call failed: %s"%e)
Server code snippet:
import rospy
from test_service.srv import MySrvFile, MySrvFileResponse
def callback_function(req):
print(req)
return MySrvFileResponse('Hello client, your message received.')
rospy.init_node('server')
rospy.Service('a_topic', MySrvFile, callback_function)
rospy.spin()
MySrvFile.srv
string request
---
string response
Server out:
request: "Hi, do you hear me?"
Client out:
Client: Hi, do you hear me?
Server: Hello client, your message received.
Learn more in ros-wiki
Project repo on GitHub.
[UPDATE]
If you are looking for fast communication, TCP-ROS communication is not your purpose because it is slower than a broker-less communicator like ZeroMQ (it has low latency and high throughput):
ROS-Service pattern equivalent in ZeroMQ is REQ/REP (client/server)
ROS publisher/subscriber pattern equivalent in ZeroMQ is PUB/SUB
ROS publisher/subscriber with waitformessage equivalent in ZeroMQ is PUSH/PULL
ZeroMQ is available in both Python and C++
Also, to transfer huge amounts of data (e.g. pointcloud), there is a mechanism in ROS called nodelet which is supported only in C++. This communication is based on shared memory on a machine instead of TCP-ROS socket.
What exactly is a nodelet?
Since you want to stick with publish/ subscribers, assuming from your comment, that services are to slow I would have a look at waitForMessage (Documentation).
And for an example on how to use it you can have a look at this ros answers question.
All you need to do is to publish your data and immediately call waitForMessage on the output topic and manually pass the received message to your "callback".
I hope this is what you were looking for.
To get this request/reply behaviour ROS has a mechanism called ROS service.
You can specify the input and output of your service in a service file similar to a ROS message definition. You can then call the service of a node with your input and the call will receive an output when the service is finished.
Here is a tutorial how to use this mechanism in python. If you prefer C++ there is also one, you should find it.
I have a java client which is sending some message to an erlang server process listening on TCP.The java client sends the data using outputstream.On the server side i am using following call to uncompress the data after initialising zlib
zlib:inflate(ZStream, Data),
where Data is binary.I am getting data_error on this call.
Under what conditions do I get data_error with zlib.
Try setting a 0 or -15 WindowBits, would help if you paste more code like the zlib:inflateInit call, the binary dump of Data variable, and the Java side zlib init.
If you are streaming the data in relatively small chunks, you can use my ezlib on Github.
Performance wise it's around 69 % faster than erlang driver and also works better when you have concurrent sessions.
To integrate, use rebar as you would do for any other erlang app. To run a small example:
StringBin = <<"this is a string compressed with zlib nif library">>,
{ok, DeflateRef} = ezlib:new(?Z_DEFLATE),
{ok, InflateRef} = ezlib:new(?Z_INFLATE),
CompressedBin = ezlib:process(DeflateRef, StringBin),
DecompressedBin = ezlib:process(InflateRef, CompressedBin).
Do not use it to compress large blocks, because you can block the erlang scheduler. I will change this in the subsequent versions.
I have a problem with changing the standard options used by an Axis 1.4 generated web service client code.
We consume a certain web service of a partner who is using the old RPC/Encoded style, which basically means we're not able to go for Axis 2 but are limited to Axis 1.4.
The service client is retrieving data from the remote server through our proxy which actually runs quite nicely.
Our application is deployed as a servlet. The retrieved response of the foreign web service is inserted into a (XML) document we provide to our internal systems/CMS.
But if the external service is not responding - which didn't happen yet but might happen at anytime - we want to degrade nicely and return our produced XML document without the calculated web service information within a resonable time.
The data retrieved is optional (if this specific calculation is missing it isn't a big issue at all).
So I tried to change the timeout settings. I did apply/use all methods and keys I could find in the documentation of axis to alter the connection and socket timeouts by searching the web.
None of these seems to influence the connection timeouts.
Can anyone give me advice how to alter the settings for an axis stub/service/port based on version 1.4?
Here's an example for the several configurations I tried:
MyService service = new MyServiceLocator();
MyServicePort port = null;
try {
port = service.getMyServicePort();
javax.xml.rpc.Stub stub = (javax.xml.rpc.Stub) port;
stub._setProperty("axis.connection.timeout", 10);
stub._setProperty(org.apache.axis.client.Call.CONNECTION_TIMEOUT_PROPERTY, 10);
stub._setProperty(org.apache.axis.components.net.DefaultCommonsHTTPClientProperties.CONNECTION_DEFAULT_CONNECTION_TIMEOUT_KEY, 10);
stub._setProperty(org.apache.axis.components.net.DefaultCommonsHTTPClientProperties.CONNECTION_DEFAULT_SO_TIMEOUT_KEY, 10);
AxisProperties.setProperty("axis.connection.timeout", "10");
AxisProperties.setProperty(org.apache.axis.client.Call.CONNECTION_TIMEOUT_PROPERTY, "10");
AxisProperties.setProperty(org.apache.axis.components.net.DefaultCommonsHTTPClientProperties.CONNECTION_DEFAULT_CONNECTION_TIMEOUT_KEY, "10");
AxisProperties.setProperty(org.apache.axis.components.net.DefaultCommonsHTTPClientProperties.CONNECTION_DEFAULT_SO_TIMEOUT_KEY, "10");
logger.error(AxisProperties.getProperties());
service = new MyClimateServiceLocator();
port = service.getMyServicePort();
}
I assigned the property changes before the generation of the service and after, I set the properties during initialisation, I tried several other timeout keys I found, ...
I think I'm getting mad about that and start to forget what I tried already!
What am I doing wrong? I mean there must be an option, mustn't it?
If I don't find a proper solution I thought about setting up a synchronized thread with a timeout within our code which actually feels quite awkward and somehow silly.
Can you imagine anything else?
Thanks in advance
Jens
axis1.4 java client soap wsdl2java rpc/encoded xml servlet generated alter change setup stub timeout connection socket keys methods
I think it may be a bug, as indicated here:
https://issues.apache.org/jira/browse/AXIS-2493?jql=text%20~%20%22CONNECTION_DEFAULT_CONNECTION_TIMEOUT_KEY%22
Typecast service port object to org.apache.axis.client.Stub.
(i.e)
org.apache.axis.client.Stub stub = (org.apache.axis.client.Stub) port;
Then set all the properties:
stub._setProperty(org.apache.axis.client.Call.CONNECTION_TIMEOUT_PROPERTY, 10);
stub._setProperty(org.apache.axis.components.net.DefaultCommonsHTTPClientProperties.CONNECTION_DEFAULT_CONNECTION_TIMEOUT_KEY, 10);
stub._setProperty(org.apache.axis.components.net.DefaultCommonsHTTPClientProperties.CONNECTION_DEFAULT_SO_TIMEOUT_KEY, 10);
I'm making a application in Erlang, with a GUI in Java.
I've managed to establish a connection between the to languages, but now i need to (i guess) send a message from Java to Erlang, every time I e.g press a button.
Is that the right way to go?
How would such a message look?
I've found a few good sites about this form of integration, but I feel like im not getting everything.
http://www.trapexit.org/How_to_communicate_java_and_erlang
Besides classic Java-Erlang communication via OTP jinterface you can research such methods like:
- thrift
- ice from zeroC (no official erlang binding)
- maybe two http servers on both sides (I like this approach)
- protocol buffers (rather not, it is better for larger data transfers)
You need to learn the shape of your traffic and choose the best solution.
Jinterface is not so bad, tho.. (here is official doc: http://www.erlang.org/doc/apps/jinterface/jinterface_users_guide.html)
If jinterface is too complicated you might just use the packet option on open_port and use
byte[] in_buf = new byte[256];
byte[] out_buf = new byte[256];
int in_count = System.in.read ();
int offset = 0;
do
{
int c = System.in.read (in_buf, offset, in_count-offset);
offset += c;
}
while (offset < in_count);
To read packets from erlang and to write use:
System.out.write(out_count);
System.out.write(out_buf, 0, out_count);
On the erlang side this would match with
open_port({spawn, "<path-to-java> -cp <classpath> your-java-prog",
[{packet, 1}]).
If you need larger packets use {packet, 2} or {packet, 4} and adapt the java.
Inside the packets you can run whatever protocol you like on both sides.
I am working on an application similar to yours: C++ GUI and Erlang server. I use TCP sockets to exchange messages between the GUI and server, and Erlang server patterns for handling requests (I may have more than one GUI hooked up to the server at the same time).
I have this simple piece of code that writes to a socket, then reads the response from the server. The server is very fast (responds within 5ms every time). However, while writing to the socket is quick -- reading the response from the socket is always MUCH slower. Any clues?
module UriTester
module UriInfo
class << self
def send_receive(socket, xml)
# socket = TCPSocket.open("service.server.com","2316")
begin
start = Time.now
socket.print(xml) # Send request
puts "just printed the xml into socket #{Time.now - start}"
rescue Errno::ECONNRESET
puts "looks like there is an issue!!!"
socket = TCPSocket.open("service.server.com","2316")
socket.print(xml) # Send request
end
response=""
while (line =socket.recv(1024))
response += line
break unless line.grep(/<\/bcap>/).empty?
end
puts "SEND_RECEIVE COMPLETED. IN #{Time.now - start}"
# socket.close
response
end
end
end
end
Thanks!
Writing to the socket will always be way faster than reading in this case because the write is local to the machine and the read has to wait for a response to come over the network.
In more detail, when the call to write / send returns all the system is telling you is that N bytes have been successfully copied to the sockets kernel space buffer. It does not mean that the data has actually been sent across the network yet. In fact, the data can sit in the socket buffer for quite a long time ( assuming you're using TCP ). This is because of something called the Nagle algorithm which is intended to make efficient use of network bandwidth. This unseen Nagle delay adds to the round trip time and how long till you get a response. The server might also delay it's response for the same reason adding even more to the response time.
So when you time the write and it returns quickly, that doesn't actually mean anything useful.
As mentioned earlier the read from the socket will be way longer since when you time the read you are actually timing the round trip travel time plus server response time, which is always going to be way slower than the time it takes to copy data from a user space program to a kernel buffer.
What is it that you are actually trying to measure and why?