PowerBuilder

Refresh Access Token on 401 Unauthorized and Retry (Service Account)

See more Google Cloud Storage Examples

Demonstrates how to handle an expired access token error, refresh the token, and retry the request. (In this case, the request is to download an object from Google Cloud Storage.) PowerBuilder

integer li_rc
integer li_Success
oleobject loo_SbToken
oleobject loo_Http
string ls_Url
oleobject loo_FileData
integer li_ResponseCode
oleobject loo_Fac
string ls_JsonKey
oleobject loo_GAuth
oleobject loo_TlsSock
oleobject loo_SbErrorResponse

li_Success = 0

// This example requires the Chilkat API to have been previously unlocked.
// See Global Unlock Sample for sample code.

// This example uses a previously obtained access token having permission for the 
// scope "https://www.googleapis.com/auth/cloud-platform"

// In this example, Get Google Cloud Storage OAuth2 Access Token, 
// the service account access token was saved to a text file.  This example fetches the access token from the file..
loo_SbToken = create oleobject
li_rc = loo_SbToken.ConnectToNewObject("Chilkat.StringBuilder")
if li_rc < 0 then
    destroy loo_SbToken
    MessageBox("Error","Connecting to COM object failed")
    return
end if
li_Success = loo_SbToken.LoadFile("qa_data/tokens/googleCloudStorageAccessToken.txt","utf-8")
if li_Success = 0 then
    Write-Debug "Failed to load access token."
    destroy loo_SbToken
    return
end if

loo_Http = create oleobject
li_rc = loo_Http.ConnectToNewObject("Chilkat.Http")

loo_Http.AuthToken = loo_SbToken.GetAsString()

// Construct a URL to download an object named "starfish.jpg" from the "chilkat-ocean" bucket.
loo_Http.SetUrlVar("bucket_name","chilkat-ocean")
loo_Http.SetUrlVar("object_name","starfish.jpg")
ls_Url = "https://www.googleapis.com/storage/v1/b/{$bucket_name}/o/{$object_name}?alt=media"

// If there is an error response, then we didn't actually download the file data,
// but instead we downloaded an error response..
loo_FileData = create oleobject
li_rc = loo_FileData.ConnectToNewObject("Chilkat.BinData")

li_Success = loo_Http.DownloadBd(ls_Url,loo_FileData)
li_ResponseCode = loo_Http.LastStatus
if (li_Success = 0) AND (li_ResponseCode <> 401) then
    Write-Debug loo_Http.LastErrorText
    destroy loo_SbToken
    destroy loo_Http
    destroy loo_FileData
    return
end if

if li_ResponseCode = 401 then
    Write-Debug "Received 401 Unauthorized response. Attempting to refresh the access token..."

    // May be that the access token expired.
    // Load our JSON key and request a new access token, then retry the original request.
    loo_Fac = create oleobject
    li_rc = loo_Fac.ConnectToNewObject("Chilkat.FileAccess")

    ls_JsonKey = loo_Fac.ReadEntireTextFile("qa_data/googleApi/ChilkatCloud-13a07a2e8b3f.json","utf-8")
    if loo_Fac.LastMethodSuccess <> 1 then
        Write-Debug loo_Fac.LastErrorText
        destroy loo_SbToken
        destroy loo_Http
        destroy loo_FileData
        destroy loo_Fac
        return
    end if

    loo_GAuth = create oleobject
    li_rc = loo_GAuth.ConnectToNewObject("Chilkat.AuthGoogle")

    loo_GAuth.JsonKey = ls_JsonKey
    loo_GAuth.Scope = "https://www.googleapis.com/auth/cloud-platform"
    loo_GAuth.ExpireNumSeconds = 3600
    loo_GAuth.SubEmailAddress = ""

    loo_TlsSock = create oleobject
    li_rc = loo_TlsSock.ConnectToNewObject("Chilkat.Socket")

    li_Success = loo_TlsSock.Connect("www.googleapis.com",443,1,5000)
    if li_Success <> 1 then
        Write-Debug loo_TlsSock.LastErrorText
        destroy loo_SbToken
        destroy loo_Http
        destroy loo_FileData
        destroy loo_Fac
        destroy loo_GAuth
        destroy loo_TlsSock
        return
    end if

    li_Success = loo_GAuth.ObtainAccessToken(loo_TlsSock)
    if li_Success <> 1 then
        Write-Debug loo_GAuth.LastErrorText
        destroy loo_SbToken
        destroy loo_Http
        destroy loo_FileData
        destroy loo_Fac
        destroy loo_GAuth
        destroy loo_TlsSock
        return
    end if

    loo_Fac.WriteEntireTextFile("qa_data/tokens/googleCloudStorageAccessToken.txt",loo_GAuth.AccessToken,"utf-8",0)

    // Retry the original request.
    loo_Http.AuthToken = loo_GAuth.AccessToken
    li_Success = loo_Http.DownloadBd(ls_Url,loo_FileData)
    if li_Success = 0 then
        Write-Debug loo_Http.LastErrorText
        destroy loo_SbToken
        destroy loo_Http
        destroy loo_FileData
        destroy loo_Fac
        destroy loo_GAuth
        destroy loo_TlsSock
        return
    end if

end if

if li_ResponseCode <> 200 then
    // Get the error response
    loo_SbErrorResponse = create oleobject
    li_rc = loo_SbErrorResponse.ConnectToNewObject("Chilkat.StringBuilder")

    loo_SbErrorResponse.AppendBd(loo_FileData,"utf-8",0,0)
    Write-Debug "Error response code = " + string(li_ResponseCode)
    Write-Debug "Error:"
    Write-Debug loo_SbErrorResponse.GetAsString()
    destroy loo_SbToken
    destroy loo_Http
    destroy loo_FileData
    destroy loo_Fac
    destroy loo_GAuth
    destroy loo_TlsSock
    destroy loo_SbErrorResponse
    return
end if

Write-Debug "Success."

// Save the downloaded data to a file.
li_Success = loo_FileData.WriteFile("qa_output/starfish.jpg")


destroy loo_SbToken
destroy loo_Http
destroy loo_FileData
destroy loo_Fac
destroy loo_GAuth
destroy loo_TlsSock
destroy loo_SbErrorResponse