java writeInt from php,

Question

hey all i am trying to make a data output stream in php to write back primitive data types to a java application

i created a class that write the data to an array (write it same as java do , copy from java code)

and finally i am writing back the array to the client.

feels like its not working well

for example the writeInt method send to the java client some wrong values am i doing ok ?

thank you

here is my code

private $buf   = array();


public function writeByte($b) {
  $this->buf[] = pack('c' ,$b);
}

public function writeInt($v) { 
  $this->writeByte($this->shiftRight3($v , 24) & 0xFF);
  $this->writeByte($this->shiftRight3($v , 16) & 0xFF);
  $this->writeByte($this->shiftRight3($v ,  8) & 0xFF);
  $this->writeByte($this->shiftRight3($v ,  0) & 0xFF);

}


private function shiftRight3($a ,$b){
  if(is_numeric($a) && $a < 0){
    return ($a >> $b) + (2<<~$b);
  }else{
    return ($a >> $b);
  }
}


public function toByteArray(){
    return $this->buf;
}

this is how i am setting the main php file

   header("Content-type: application/octet-stream" ,true);
   header("Content-Transfer-Encoding: binary" ,true);

this is how i am returning the data

  $arrResult = $dataOutputStream->toByteArray();
  for ($i = 0 ; $i < count($arrResult) ; $i ++){
     echo $arrResult[$i];
  }

I EDIT THE QUESTION ,ACCOURDING TO MY CODE CHANGING in the java client side seems that i have 2 bytes to read start always i have 13 , 10 , which is \r \n how come i am reading them always ?

(in my test i am sending one byte to the java client side ,

  URL u = new URL("http://localhost/jtpc/test/inputTest.php");
  URLConnection c = u.openConnection();

  InputStream in =  c.getInputStream();
  int read = 0;
  for (int j = 0; read != -1 ; j++) {
    read = in.read();
    System.out.println("More to read : " + read);
  }
 )

  the output will be ,
   More to read : 13
   More to read : 10
   More to read : 1 (this is the byte i am sending)

Is there a particular reason you're doing it this way instead of using an intermediary data transport, like JSON, WDDX, or plain old XML? — Charles
– Charles, Commented Jul 25, 2010 at 5:18
yes there is , i have a mechanism for a network protocol me and friend implemented in java ages ago , and i prefer this protocol on top of other things — shay
– shay, Commented Jul 25, 2010 at 5:29
GOT IT WEIRD.... i thing i got my sample working i wrote 3 different int values and its look fine what i had to do is ignore to first 2 bytes that i am reading , can some one help me why ? i update the post on how i am sending byte now — shay
– shay, Commented Jul 26, 2010 at 20:33

jmz · Accepted Answer · 2010-07-25 06:19:10Z

3

Php has pack() function for turning data into binary form. Unpack() reverses the operation.

$binaryInt = pack('I', $v);

answered Jul 25, 2010 at 6:19

jmz

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7 Comments

shay Over a year ago

my methods work when i print the values to log before sending them just store the data as binary data and send it wont work for me . i tried to use pack but this wont helping echo the data back has strange value in java printing them in php side looks ok so i guess this is just the binary thing

Stephen C Over a year ago

@shay - how are you "echoing back" in Java? I wouldn't expect binary data to be readable if read as bytes and converted / printed as a String.

shay Over a year ago

@jmz i use pach('c' ,$v) , working great i have another problem now

shay Over a year ago

*pack working great ,my new problem is why i am always reading \r\n from the php side

jmz Over a year ago

@Shay: I'm sorry but I don't quite follow what you mean by reading \r\n from the php side? Do you receive a CRLF when you expect something else, or the actual string backslash-r-backslash-n?

|

Community · Accepted Answer · 2021-10-07 05:59:28Z

3

The one thing that strikes me as odd is that you are setting the content type to application/zip, but you don't seem to be creating a ZIP encoded output stream. Is this an oversight ... or does PHP perform the encoding for you without you asking?

EDIT

According to RFC 2046, the recommended content type for a binary data format whose content type is not standardized is "application/octet-stream". There is also a practice of defining custom content subtypes with a name starting with "x-" (for experimental), but RFC 2046 says that this practice is now strongly discouraged.

edited Oct 7, 2021 at 5:59

CommunityBot

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answered Jul 25, 2010 at 6:44

Stephen C

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7 Comments

shay Over a year ago

just trying to force it to some binary data . there is a generic content type for raw data ?

shay Over a year ago

i tried this header("Content-type: application/octet-stream"); header("Content-Transfer-Encoding: binary"); not helping see my comment to previous post

Stephen C Over a year ago

@shay - Oh well. But you needed to fix it anyway. Otherwise any client (e.g. browser) that that paid attention to content-type headers would attempt to treat the response as ZIP file!

shay Over a year ago

hey thank you Stephen C , i was able to echo the bytes data back to java , using java DataInputStream to read the data types , but i have to read the two first bytes ,in order to start reading primitive data type , before i am echoing back in php i see that my array length is 4 , in java side i need to read first 2 bytes , then read the INT (which is 4 bytes)

shay Over a year ago

also i update my question for what i am doing , the 4 bytes that i am reading is the the source code of DatainputStream.readInt();

|

user207421 · Accepted Answer · 2010-07-25 06:14:23Z

1

You don't need that shiftRight3() method, just use >>, as you are masking the result, and then turning it into a chr(). Throw it away.

answered Jul 25, 2010 at 6:14

user207421

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