I am getting an error when running the following code in python 3, I look all over but could not find a right way to do it. any help will be appreciated.
raise TypeError('unicode strings are not supported, please encode to bytes: {!r}'.format(seq))
TypeError: unicode strings are not supported, please encode to bytes: 'relay read 7\n\r'
I need to send the following string via serial port: relay read #of relay.
import sys
import serial
if (len(sys.argv) < 2):
print ("Usage: relayread.py <PORT> <RELAYNUM>\nEg: relayread.py COM1 0")
sys.exit(0)
else:
portName = sys.argv[1];
relayNum = sys.argv[2];
#Open port for communication
serPort = serial.Serial(portName, 19200, timeout=1)
if (int(relayNum) < 10):
relayIndex = str(relayNum)
else:
relayIndex = chr(55 + int(relayNum))
serPort.write("relay read "+ relayIndex + "\n\r")
response = serPort.read(25)
if(response.find("on") > 0):
print ("Relay " + str(relayNum) +" is ON")
elif(response.find("off") > 0):
print ("Relay " + str(relayNum) +" is OFF")
#Close the port
serPort.close()
Use the string's encode method to construct the corresponding byte sequence.
In this case all of the characters in the string are in the ASCII range so it doesn't really matter which encoding scheme you use. (Differences between encoding schemes generally only matter when you're dealing with non-ASCII characters, ones whose ord() value is greater than 127.) So in this case you don't even need to specify a particular encoding scheme, you can simply use the encode method with no argument and let Python apply the platform's default encoding.
To do that, change this:
serPort.write("relay read "+ relayIndex + "\n\r")
to this:
serPort.write(("relay read "+ relayIndex + "\n\r").encode())
You'll probably have to do the reverse operation to get a string from the byte sequence returned by serPort.read. Change this:
response = serPort.read(25)
to:
response = serPort.read(25).decode()
BTW, it's typical for line endings in transmitted data to be represented by a Carriage Return followed by a Line Feed, or "\r\n". In your serPort.write call you're using the reverse of that, "\n\r". That's unusual but if that's what your device needs then so be it.
I'm trying to concat 2 variables Address and Payload. After that I want to send them with http to a server but I have 2 problems. When i try to concat the 2 variables with a delimiter ';' it doesn't work. Also sending the data of Payload or Address doesn't work. This is my code:
handle_rx(Gateway, #link{devaddr=DevAddr}=Link, #rxdata{port=Port, data= RxData }, RxQ)->
Data = base64:encode(RxData),
Devaddr = base64:encode(DevAddr),
TextAddr="Device address: ",
TextPayload="Payload: ",
Address = string:concat(TextAddr, Devaddr),
Payload = string:concat(TextPayload, Data),
Json=string:join([Address,Payload], "; "),
file:write_file("/tmp/foo.txt", io_lib:fwrite("~s.\n", [Json] )),
inets:start(),
ssl:start(),
httpc:request(post, {"http://192.168.0.121/apiv1/lorapacket/rx", [], "application/x-www-form-urlencoded", Address },[],[]),
ok;
handle_rx(_Gateway, _Link, RxData, _RxQ) ->
{error, {unexpected_data, RxData}}.
I have no errors that I can show you. When I write Address or Payload individually to the file it works but sending doesn't work...
Thank you for your help!
When i try to concat the 2 variables with a delimiter ';' it doesn't work.
5> string:join(["hello", <<"world">>], ";").
[104,101,108,108,111,59|<<"world">>]
6> string:join(["hello", "world"], ";").
"hello;world"
base64:encode() returns a binary, yet string:join() requires string arguments. You can do this:
7> string:join(["hello", binary_to_list(<<"world">>)], ";").
"hello;world"
Response to comment:
In erlang the string "abc" is equivalent to the list [97,98,99]. However, the binary syntax <<"abc">> is not equivalent to <<[97,98,99]>>, rather the binary syntax <<"abc">> is special short hand notation for the binary <<97, 98, 99>>.
Therefore, if you write:
Address = [97,98,99].
then the code:
Bin = <<Address>>.
after variable substitution becomes:
Bin = <<[97,98,99]>>.
and that isn't legal binary syntax.
If you need to convert a string/list contained in a variable, like Address, to a binary, you use list_to_binary(Address)--not <<Address>>.
In your code here:
Json = string:join([binary_to_list(<<Address>>),
binary_to_list(<<Payload>>)],
";").
Address and Payload were previously assigned the return value of string:concat(), which returns a string, so there is no reason to (attempt) to convert Address to a binary with <<Address>>, then immediately convert the binary back to a string with binary_to_list(). Instead, you would just write:
Json = string:join(Address, Payload, ";")
The problem with your original code is that you called string:concat() with a string as the first argument and a binary as the second argument--yet string:concat() takes two string arguments. You can use binary_to_list() to convert a binary to the string that you need for the second argument.
Sorry I'm new to Erlang
As with any language, you have to study the basics and write numerous toy examples before you can start writing code that actually does something.
You don't have to concatenate strings. It is called iolist and is one of best things in Erlang:
1> RxData = "Hello World!", DevAddr = "Earth",
1> Data = base64:encode(RxData), Devaddr = base64:encode(DevAddr),
1> TextAddr="Device address", TextPayload="Payload",
1> Json=["{'", TextAddr, "': '", Devaddr, "', '", TextPayload, "': '", Data, "'}"].
["{'","Device address","': '",<<"RWFydGg=">>,"', '",
"Payload","': '",<<"SGVsbG8gV29ybGQh">>,"'}"]
2> file:write_file("/tmp/foo.txt", Json).
ok
3> file:read_file("/tmp/foo.txt").
{ok,<<"{'Device address': 'RWFydGg=', 'Payload': 'SGVsbG8gV29ybGQh'}">>}
I want to create an HTTP static file server using java NIO and it works fine for small files, but seems to truncate the HTTP response for larger files (672 KB out of a 3.8 MB image is returned according to my Chrome Inspector, and my browser displays a a partially corrupted image). Is this code below incorrect?
(I know there are existing libraries for this and eventually I will use one in my project. But initially I want to implement a basic one myself to see if my project concept is feasible.)
Iterator<SelectionKey> keys = selector.selectedKeys().iterator();
while (keys.hasNext()) {
SelectionKey key = keys.next();
keys.remove();
if (key.isAcceptable()) {
// New Client encountered
serverSocket.accept().configureBlocking(false)
.register(selector, SelectionKey.OP_READ);
} else if (key.isReadable()) {
// Additional data for existing client encountered
SocketChannel selectedClient = (SocketChannel) key.channel();
ByteBuffer buffer = ByteBuffer.allocate(548);
String requestedFile2 = getRequstedFile(key, selectedClient, buffer);
buffer.clear();
buffer.flip();
FileChannel fc = FileChannel.open(Paths.get(requestedFile2));
String string = "HTTP/1.1 200 Ok\nContent-Type: image/jpeg\nContent-Length: "
+ (Files.size(Paths.get(requestedFile2)) + "\n\n");
selectedClient.write(ByteBuffer.wrap(string.getBytes()));
while (fc.read(buffer) > -1) {
buffer.flip(); // read from the buffer
selectedClient.write(buffer);
buffer.clear();
}
selectedClient.close();
}
}
(Exception handling etc. omitted for brevity)
EDIT
I have a content-length-mismatch error message. So what is the right way to determine the HTTP response size when reading a file's contents using the NIO API?
buffer.clear();
That should be
buffer.compact();
and the loop should be
while (fc.read(buffer) > 0 || buffer.position() > 0)
You're assuming everything got written by the write.
Also you need to change the HTTP header line terminators to \r\n.
And you need to study RFC 2616 about the content length.
I guess you have to check return value from selectedClient.write(), check the SocketChannel.write() documentation:
Unless otherwise specified, a write operation will return only after writing all of the r requested bytes. Some types of channels, depending upon their state, may write only some of the bytes or possibly none at all.
Which could be the case here. Either add another inner loop which would write to output as long as there are bytes remaining in the buffer. Or you can amend the loop according to example in ByteBuffer.compact(): http://docs.oracle.com/javase/7/docs/api/java/nio/ByteBuffer.html#compact()
while (buffer.position() > 0 || fc.read(buffer) > 0) {
buffer.flip(); // read from the buffer
selectedClient.write(buffer);
buffer.compact();
}
And remember that the code supposes that selectedClient is blocking. If that wasn't the case, you would need to invoke another select() waiting on the selectedClient becoming writable...
I am using gawk 4.1.1 to parse Cisco IOS configuration files, comparing switch configs to the routers above them, to eventually pull out IP addresses. My problem is I need to skip a record (interface) if I have already processed the vlan before. The catch is I am processing multiple files from different sites, and each site has it's own vlans.
So I thought an array of arrays would work best, where array[pop] could be array[den01], array[nyc01], etc. Dynamically creating those index-arrays from the variable pop, pulled from a text file.
The data processing works fine, except that it produces duplicate vlan numbers at a given site. The "dbfile" contains every vlan seen on every switch, from every site, and some people have redundant links so their vlan shows up twice.
Below is a snippet of my code:
#!/bin/bash
for i in `cat dbfile` ]; do
# set lots of variables to pull into awk
awk -v i=$i -v name=$name -v intname=$intname -v cvupfile=$cvupfile -v pop=$pop -v cid=$cid -v custvlan=$custvlan 'BEGIN { RS="!"; FS=" "; array[pop][0] = "" }
{
if ( $1 ~ "interface" && $2 ~ "Vlan" )
{
# trim Vlan ID so only the actual vlan number remains
seenvlan=gensub(/^Vlan/, "", "g", $2)
if ( seenvlan == custvlan )
{
# this is where trouble starts. I never get this IF to be true
if ( custvlan in array[pop] )
{
print "Duplicate VLAN found!"
}
else
{
# vlan is unique, make index for it
array[pop][custvlan]=custvlan
# debug output
for ( i in array )
print "This is first element: " i
for ( j in array[i] )
print "This is second element: " array[i][j]
print "Here is value from array: " array[pop][custvlan]
exit
}
}
}
}
END {
}' $crt
done
Here is some sample output. It shows 3 records processed. The fact that "This is the second element" is printed twice seems like a clue, but I'm not sure what it means. I am making a bunch of null indexes under array[pop]?
This is first element: den01
This is second element:
This is second element: 235
Here is value from array: 235
This is first element: den01
This is second element:
This is second element: 279
Here is value from array: 279
This is first element: den01
This is second element:
This is second element: 131
Here is value from array: 131
A user can POST a document to our web service. We stream it elsewhere. But, at the end of the streaming, we need to be sure they didn't lie about their Content-Length.
I assume if headerContentLength > realContentLength, the request will just wait for them to send the rest, eventually timing out. So that's probably OK.
What about if headerContentLength < realContentLength? I.e. what if they keep sending data after they said they were done?
Is this taken care of by Node.js in any way? If not, what is a good way to check? I suppose I could just count up the bytes inside of some data event listeners---i.e., req.on("data", function (chunk) { totalBytes += chunk.length; }). That seems like a kludge though.
To check the actual length of the request, you have to add it up yourself. The data chunks are Buffers and they have a .length property that you can add up.
If you specify the encoding with request.setEncoding(), your data chunks will be Strings instead. In that case, call Buffer.byteLength(chunk) to get the length. (Buffer is a global object in node.)
Add up the total for each of your chunks and you'll know how much data was sent.
Here's a rough (untested) example:
https.createServer(function(req, res) {
var expected_length = req.headers['content-length']; // I think this is a string ;)
var actual_length = 0;
req.on('data', function (chunk) {
actual_length += chunk.length;
});
req.on('end', function() {
console.log('expected: ' + expected_length + ', actual: ' + actual_length);
});
});
Note: length refers to the maximum length of the Buffer's content, not the actual length. However, it works in this case because chunk buffers are always created at the exact correct length. Just be aware of that if you're working with buffers somewhere else.