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digitalmars.D - Interprocess Communication between Python and D

reply Utk <bhiogade20 gmail.com> writes:
I'm trying to send data from python script to D using tcp 
sockets. As I'm new to D I referred to 
https://forum.dlang.org/post/lqahvaeqddaddnkhpfyf forum.dlang.org 
for client and server code. When I'm sending packed data from 
python it is of the form
```d
u'\x0f\x10\x00\x00\x00\x01\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x04\x00\x00\x00\x04\x00\x00\x00\x00\x00\x00\x00\xbaH\x0c\x00'
```
basically a string! This data is successfully received on the 
client side in D but when the data is changing to
```d
u'\x0f\x0c\x00\x00\x00\x01\x00\x00\x00\x00\x00\x01\x00\x00\x00\x00\x00\x00\x00\x00\x04\x00\x00\x00\x00\x00\x00\x00'
```
I'm receiving nothing on the client-side in D.
Client code:
```d
void main() {
     import std.socket, std.stdio;
     auto socket = new Socket(AddressFamily.INET,  
SocketType.STREAM);
     char[1024] buffer;
     socket.connect(new InternetAddress("127.0.0.1", 10000));
     auto received = socket.receive(buffer); // wait for the 
server to say hello
     writeln("Server said: ", buffer[0 .. received]);
}
```
(same code as mentioned in the above link)
**Can someone please help me with this?**
Also when I'm sending the data in the 1st format, I'm receiving 
```�H``` as an output on the client, what changes in code should 
I make so that I receive the data in the same format as sent from 
Python?
Jun 23 2021
next sibling parent reply jfondren <julian.fondren gmail.com> writes:
On Thursday, 24 June 2021 at 04:28:45 UTC, Utk wrote:

 I'm trying to send data from python script to D using tcp 
 sockets. As I'm new to D I referred to 
 https://forum.dlang.org/post/lqahvaeqddaddnkhpfyf forum.dlang.org for client
and server code. When I'm sending packed data from python it is of the form
 ```d
 u'\x0f\x10\x00\x00\x00\x01\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x04\x00\x00\x00\x04\x00\x00\x00\x00\x00\x00\x00\xbaH\x0c\x00'
 ```
 basically a string! This data is successfully received on the 
 client side in D but when the data is changing to
 ```d
 u'\x0f\x0c\x00\x00\x00\x01\x00\x00\x00\x00\x00\x01\x00\x00\x00\x00\x00\x00\x00\x00\x04\x00\x00\x00\x00\x00\x00\x00'
 ```
 I'm receiving nothing on the client-side in D.
 Client code:
 ```d
 void main() {
     import std.socket, std.stdio;
     auto socket = new Socket(AddressFamily.INET,  
 SocketType.STREAM);
     char[1024] buffer;
     socket.connect(new InternetAddress("127.0.0.1", 10000));
     auto received = socket.receive(buffer); // wait for the 
 server to say hello
     writeln("Server said: ", buffer[0 .. received]);
 }
 ```
 (same code as mentioned in the above link)
 **Can someone please help me with this?**
 Also when I'm sending the data in the 1st format, I'm receiving 
 ```�H``` as an output on the client, what changes in code 
 should I make so that I receive the data in the same format as 
 sent from Python?


As the buffer's a char[], it's being printed as a string, which
means dumping those raw NUL bytes and such into the terminal, 
which
is displaying them in a way that's surprising you.

But all of that's working just fine. Change the buffer to 
ubyte[1024]
and with no other changes you'll get this output:

Server said: [15, 16, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 
4, 0, 0, 0, 4, 0, 0, 0, 0, 0, 0, 0, 186, 72, 12, 0]
Jun 23 2021
next sibling parent jfondren <julian.fondren gmail.com> writes:
On Thursday, 24 June 2021 at 05:53:51 UTC, jfondren wrote:

 Server said: [15, 16, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 
 4, 0, 0, 0, 4, 0, 0, 0, 0, 0, 0, 0, 186, 72, 12, 0]


Some alternatives:

Server said: 
\0f\0c\00\00\00\01\00\00\00\00\00\01\00\00\00\00\00\00\00\00\04\00\00\00\00\00\00\00

from:

```d
ubyte[1024] buffer;
...
writefln("Server said: %(\\%02x%)", buffer[0 .. received]);
```

Server said: 
"\x0F\f\0\0\0\x01\0\0\0\0\0\x01\0\0\0\0\0\0\0\0\x04\0\0\0\0\0\0\0"

from:

```d
char[1024] buffer;
...
writefln("Server said: %(%s%)", [buffer[0 .. received]]);
```
Jun 23 2021
prev sibling parent reply Utk <bhiogade20 gmail.com> writes:
On Thursday, 24 June 2021 at 05:53:51 UTC, jfondren wrote:

 On Thursday, 24 June 2021 at 04:28:45 UTC, Utk wrote:
 But all of that's working just fine. Change the buffer to 
 ubyte[1024]


Oh, I see! Thanks a lot, will try that.
Jun 23 2021
parent reply Nicholas Wilson <iamthewilsonator hotmail.com> writes:
On Thursday, 24 June 2021 at 06:10:08 UTC, Utk wrote:

 Oh, I see! Thanks a lot, will try that.


For future questions please use the learn forum:

https://forum.dlang.org/group/learn
Jun 24 2021
parent Utk <bhiogade20 gmail.com> writes:
On Thursday, 24 June 2021 at 07:56:35 UTC, Nicholas Wilson wrote:

 On Thursday, 24 June 2021 at 06:10:08 UTC, Utk wrote:

 Oh, I see! Thanks a lot, will try that.


 For future questions please use the learn forum:

 https://forum.dlang.org/group/learn


Sure!
Jun 24 2021
prev sibling parent reply Adam D Ruppe <destructionator gmail.com> writes:
On Thursday, 24 June 2021 at 04:28:45 UTC, Utk wrote:

 (same code as mentioned in the above link)


That code was assuming you were sending strings which is why it 
did that.

I wrote a newer version of that socket tutorial btw here:

http://dpldocs.info/this-week-in-d/Blog.Posted_2019_11_11.html

But I again used `char` there. However, if you just change that 
to `ubyte`, you can use the rest of the code for binary data.

(technically, the code works the same way, it is just the `write` 
that formats it differently for char vs ubyte when it is 
displayed, but still ubyte is generally the  right thing to do 
anyway, i probably should have used it even if i am sending hello 
strings.)
Jun 24 2021
parent Utk <bhiogade20 gmail.com> writes:
On Thursday, 24 June 2021 at 12:06:30 UTC, Adam D Ruppe wrote:

 On Thursday, 24 June 2021 at 04:28:45 UTC, Utk wrote:

 (same code as mentioned in the above link)


 That code was assuming you were sending strings which is why it 
 did that.

 I wrote a newer version of that socket tutorial btw here:

 http://dpldocs.info/this-week-in-d/Blog.Posted_2019_11_11.html

 But I again used `char` there. However, if you just change that 
 to `ubyte`, you can use the rest of the code for binary data.

 (technically, the code works the same way, it is just the 
 `write` that formats it differently for char vs ubyte when it 
 is displayed, but still ubyte is generally the  right thing to 
 do anyway, i probably should have used it even if i am sending 
 hello strings.)


I see! Thanks a lot for the information and your code snippets, 
they helped a lot!
Jun 24 2021