how to tell if on internet or not and switch to local SQL db if not

[DougP]

I have an app on my tablet PC. its written in ASP.net 4.5 using vb.net
When I am not able to connect to the internet I would like it to use the local database.
How is the easiest way to determine if it can conenct to the WEB database on a hosted server or not, then switch to the local connection?

If  can connect to web db then
 Public gblConnectionString = ConfigurationManager.ConnectionStrings("WEBConnectionString").ConnectionString
Else
    'Public gblConnectionString = ConfigurationManager.ConnectionStrings("LocalConnection").ConnectionString
End if

DougP

 

[jbenson001]

Create an HTTPWebRequest object and try to hit a website. Look for the HTTPResponse that comes back.

 

[DougP]

Ok so I got this
but what am I looking for?
If I use myReq.ContentLength I get -1 whether its a valid URL or not
for Instance I used something that does not exist
"Your requested host "somejunkyplace.com" could not be resolved by DNS."
and still got -1.

 Dim myReq As HttpWebRequest = _
            WebRequest.Create("[URL unfurl="true"]http://www.mysite.com/")[/URL]

    If myReq.????? = something then
        ' we are conencted
   Else
       'we are not
   end if

DougP

 

[DougP]

Ok I got this to work. to test it put in both a "REAL" and invalid WEB site.

 Public Function AreWeOnLine() As Boolean
        Dim OnLineStatus As Boolean
        Try
            Dim myReq As HttpWebRequest = _
               WebRequest.Create("[URL unfurl="true"]http://www.ValidWEBSite.com/")[/URL]
            myReq.Method = "Get"
            Dim res As HttpWebResponse = myReq.GetResponse()
            Dim sr As Stream = res.GetResponseStream()
            Dim sre As StreamReader = New StreamReader(sr)
            Dim s As String = sre.ReadToEnd()
            Debug.Print(s)
            OnLineStatus = True
        Catch ex As Exception
            OnLineStatus = False
        End Try
        Return OnLineStatus
    End Function

DougP

 

[jbenson001]

That is a clever way to check if no site can be reached.
You can also check if the httpWebResponse isNot Nothing andalso httpWebResponse.ContentLenght >0

There is also a StatusCode and StatusDescription on the response object.

 

[jbenson001]

http://msdn.microsoft.com/en-us/library/debx8sh9.aspx