B4X

Send a Staged REST Request with a Streamed Body

Demonstrates Rest.SendReqStreamBody, which sends a request whose body is read from a Stream, then reads the response in separate steps.

The file paths are relative to the application's current working directory. Absolute paths may also be used. Supply the paths appropriate to your own environment.

Background. The staged request model separates sending from reading: a SendReq method transmits the request, ReadResponseHeader reads the status line and headers, and a ReadResp method reads the body. This gives fine control over large or streamed messages compared with the single-call full-request methods.

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Dim success As Boolean = False

Dim rest As ChilkatRest
rest.Initialize("rest")
Dim bTls As Boolean = True
Dim bAutoReconnect As Boolean = True
success = rest.Connect("example.com", 443, bTls, bAutoReconnect)
If success = False Then
    Log(rest.LastErrorText)
    Return
End If


'  The file paths are relative to the application's current working directory.  Absolute paths
'  may also be used.  Supply the paths appropriate to your own environment.

'  The request body is read from a Stream whose source is a local file.
Dim bodyStream As ChilkatStream
bodyStream.Initialize("bodyStream")
bodyStream.SourceFile = "qa_data/upload.json"

rest.AddHeader("Content-Type", "application/json")

'  Send the request, reading the body from the stream.  The 3rd argument is the Stream.
success = rest.SendReqStreamBody("POST", "/api/upload", bodyStream)
If success = False Then
    Log(rest.LastErrorText)
    Return
End If


'  After sending, read the response status line and header fields.  The return value is the HTTP
'  status code, or -1 if no response was received.
Dim statusCode As Int = rest.ReadResponseHeader
If statusCode < 0 Then
    Log(rest.LastErrorText)
    Return
End If

Log("Response status code: " & statusCode)

'  Read the response body as text.
Dim responseBody As String = rest.ReadRespBodyString
If rest.LastMethodSuccess = False Then
    Log(rest.LastErrorText)
    Return
End If

Log(responseBody)