Android Question Not able to send file with MQTT

[microbox]

Good day everyone! I would like to send image file(less than 4mb) to other online user. Sending with only text message is no problem.. but when trying to send with file keeps disconnecting. Can you have a moment to look into my the codes below.

Public Sub SendMessage(Body As String)
    If connected Then
        client.Publish2("all", CreateMessage(Body), 0, False)
    End If
End Sub


Private Sub CreateMessage(Body As String) As Byte()
    Dim m As Message
    m.Initialize
    m.Body = Body
    Log(m.Body)
    
    If  Main.gvFileName.Length > 1 Then
        If File.Exists(File.DirRootExternal & "/Download" , Main.gvFileName) Then
                Main.gvFolderPath = File.DirRootExternal & "/Download"
                Dim b() As Byte = File.ReadBytes(Main.gvFolderPath,Main.gvFileName)
                m.Body = Body
                m.From = currentName
                m.filename = Main.gvFileName
                m.Image = b
                Log("with file attached")
        End If
        
    Else
            m.Body = Body
            m.From = currentName
            Log("only message")
    
    End If
    Log(">> " & m.Body & " " & m.From & " " & m.filename & " L:" & m.Image.Length)
    Main.gvFileName = ""
    'client.Publish2("all", serializator.ConvertObjectToBytes(m), 0, True)
    Return serializator.ConvertObjectToBytes(m)
End Sub

Please let me know where I'm doing it wrong. Thanks for the help.

 

[Erel]

Which broker are you using? Are there any errors in the logs of the clients or broker?

What happens if you try to send a small file?

 

[microbox]

@Erel I'm still new to this, using jMqttBroker2. There are no errors, but when I try to send with file it terminates the connection. The same when sending small file.
I attached the file I'm working..kindly check if you have time. I appreciate it very much.

 

[Erel]

Does it happen with a very small file?

Try to increase the maximum packet size: https://www.b4x.com/android/forum/t...-limitation-on-messagesize.133081/post-840733

 

[microbox]

Thanks for the quick response @Erel, I will try to test to send a small file tonight. The code below gives an error.

Sub SetMaxMessageSize(broker As MqttBroker, MaxSize As String)
    broker.As(JavaObject).GetFieldJO("config").RunMethod("setProperty", Array("netty.mqtt.message_size", MaxSize))
End Sub

Undeclared variable 'javaobject' is used before it was assigned any value.

 

[Erel]

Check the JavaObject library and make sure to use B4A v11.

 

[microbox]

Check the JavaObject library and make sure to use B4A v11.

I have updated to B4A v11 but unfortunately when sending file(even small) closes the connection and does not transmit the file.
Below is the print log when it close the connection.

Log(">> " & m.Body & " " & m.From & " " & m.filename & " L:" & m.Image.Length)
>> Tom howdy Sam Josie.pdf L:55418

This is the part of the code that sends the message with file converted to bytes

If  Main.gvFileName.Length > 1 Then
        If File.Exists(File.DirRootExternal & "/Download" , Main.gvFileName) Then
                Main.gvFolderPath = File.DirRootExternal & "/Download"
                Dim b() As Byte = File.ReadBytes(Main.gvFolderPath,Main.gvFileName)
                m.Body = Body
                m.From = currentName
                m.filename = Main.gvFileName
                m.Image = b
                Log("with file attached")
        End If
 End if
 Return serializator.ConvertObjectToBytes(m)

 

[DonManfred]

What is the targetsdk in your app?
Are you sure you have access to the file you want to send?
What is the size of the b() Bytearray?

Also you are using two path references.
File.DirRootExternal & "/Download" when using File.Exists

and Main.gvFolderPath when reading the file.

 

[microbox]

What is the targetsdk in your app?
Are you sure you have access to the file you want to send?
What is the size of the b() Bytearray?

Also you are using two path references.
File.DirRootExternal & "/Download" when using File.Exists

and Main.gvFolderPath when reading the file.

Good eve @DonManfred,
Target sdk is 29, b = 55418. I'm pretty sure I got access to the file. But I will test more to check it.

 

[Erel]

1. Make sure that Message is declared in the Main module of all relevant apps.
2. Better to rename it to MBMessage or any other more unique name to avoid conflicts.
3. Forget from simply accessing File.DirRootExternal. It is no longer possible.
4. Test with this code:

Private Sub CreateMessage(Body As String) As Byte()
    Dim m As Message
    m.Initialize
    m.Body = Body
    m.From = currentName
    m.Filename = Main.gvFileName
    m.Image = Array As Byte(1, 2, 3)
    Return serializator.ConvertObjectToBytes(m)
End Sub

 

[microbox]

1. Make sure that Message is declared in the Main module of all relevant apps.
2. Better to rename it to MBMessage or any other more unique name to avoid conflicts.
3. Forget from simply accessing File.DirRootExternal. It is no longer possible.
4. Test with this code:

Private Sub CreateMessage(Body As String) As Byte()
    Dim m As Message
    m.Initialize
    m.Body = Body
    m.From = currentName
    m.Filename = Main.gvFileName
    m.Image = Array As Byte(1, 2, 3)
    Return serializator.ConvertObjectToBytes(m)
End Sub

@Erel thanks I will try it.

 

[microbox]

Hi @Erel, just a quick question.. sorry but I don't understand this line

m.Image = Array As Byte(1, 2, 3)

in my understanding m.image should be in array bytes (converted) from a specified file like below
Dim b() As Byte = File.ReadBytes(Main.gvFolderPath,Main.gvFileName)
m.Image = b
in m.Image = Array As Byte(1, 2, 3) how does it access the file?

 

[DonManfred]

in my understanding m.image should be in array bytes (converted) from a specified file like below

Yes. But the code ONLY creates a Array with 3 Byte. There is no single file involved in this Code.

TEST IT IF THIS WORKS or not.

If this do not work then you don´t need to try to access a file.
Get the short byte array working first.

 

[microbox]

@DonManfred it works, got it send the file( of 3 bytes).

3. Forget from simply accessing File.DirRootExternal. It is no longer possible.

How could I access it?

 

[Erel]

All options are listed here: https://www.b4x.com/android/forum/t...list-of-other-related-methods.129897/#content
Why are you using File.DirRootExternal?

 

[microbox]

All options are listed here: https://www.b4x.com/android/forum/t...list-of-other-related-methods.129897/#content
Why are you using File.DirRootExternal?

@Erel thanks for the response..I have my files in the Download folder to send to another device. I can transfer it to another folder. I'll have a read on the options accessible storage.

 

[microbox]

I moved the file to the application folder and access it, but I still can not send the file.

Private Sub CreateMessage(Body As String) As Byte()
    Dim m As MessageU
    m.Initialize
    m.Body = Body
    m.From = currentName
    Main.gvFileName = "sample.pdf"
    m.Filename = Main.gvFileName
    Dim DirFile As String
    DirFile = rp2.GetSafeDirDefaultExternal("")
    Log(DirFile)
    Dim b() As Byte = File.ReadBytes(DirFile, Main.gvFileName)
    m.Image = b
    Log(b.Length)

    Return serializator.ConvertObjectToBytes(m)
End Sub

..and it closes the connection.