B4R Tutorial Downloading a Web page with ESP8266

Erel

Administrator
Staff member
Licensed User
Edit: use rHttpUtils2 instead: https://www.b4x.com/android/forum/threads/module-rhttputils2-http-client.74785/#content
As a general rule, I recommend to use Raspberry Pi with B4J to interact with web servers or http clients. It is much more powerful and simpler to develop. The Arduino and ESP8266 strengths are in other domains.

This small example sends a http request with WiFiSocket and reads the response with AsyncStreams.

B4X:
Sub Process_Globals
   Public Serial1 As Serial
   Private wifi As ESP8266WiFi
   Private astream As AsyncStreams
   Private socket As WiFiSocket
End Sub

Private Sub AppStart
   Serial1.Initialize(115200)
   Log("AppStart")
   If wifi.Connect("dlink") Then 'change as needed
     Log("Connected to router")
   Else
     Log("Failed to connect")
     Return
   End If
   Connect(0)
End Sub

Sub Connect(unused As Byte)
   If socket.ConnectHost("example.com", 80) = False Then
     Log("trying to connect again")
     CallSubPlus("Connect", 1000, 0)
     Return
   End If
   Log("Connected to server")
   astream.Initialize(socket.Stream, "Astream_NewData", "Astream_Error")
   Dim eol() As Byte = Array As Byte(13, 10)
   astream.Write("GET / HTTP/1.1".GetBytes)
   astream.Write(eol)
   astream.Write("Host: www.example.com".GetBytes)
   astream.Write(eol)
   astream.Write("Connection: close".GetBytes)
   astream.Write(eol)
   astream.Write(eol)
End Sub

Sub Astream_NewData (Buffer() As Byte)
   Log(Buffer)
End Sub

Sub Astream_Error
   Log("Disconnected")
End Sub
The html page will be printed to the logs.

This code depends on the following libraries:
rESP8266, rESP8266WiFi and rRandomAccessFile.
 
Last edited:

John Decowski

Member
Licensed User
I try to download simple website hosted by my own iis server and returns http error 400 bad request invalid verb

Any ideas?
 
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