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Rabbit80Flag for United Kingdom of Great Britain and Northern Ireland asked on

http POST in Visual Basic

I am trying to learn how to perorm a http POST from within a VB application. The idea is to upload a file  (which will be PDF) and get back a result which i then use later.

The upload url is http://server/webservices/upload.php
Required info is Filename and SessionID both of which I know.

How do I do this in Visual Basic 2008?
Visual Basic Classic

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8/22/2022 - Mon


thanks, these links are helping. The problem I am facing at the moment is that I am getting a "session not specified" error message. I dont know where and how to add this info. I have created a Session_ID (There was a mistake in my first post - needs the underscore) using SOAP, but I now need to pass this back to the upload.php along with filename and the binary data.

I dont understand fully how the POST syntax is constructed - is there any chance you could show me what the completed POST that I send should look like?

If it helps, the following link is the source for the uploads.php script;

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James Murphy

hmm.. So are do you have a page, with no login, and you are wanting to use the sessionID to uniquely identify the user?  If so, I don't think sessionID's are unique for all time.  
I guess I am thinking ASP/ASP.NET when you say session ID.  IS this an ASP.NET (vb.net) app, or just a plain Windows Forms Vb.net app?

Let me try to explain what i am trying to do...
Using the KnowledgeTree Open Source DMS, i need to write an app that will allow me to upload files in bulk. I am using Visual Basic 2008 Express to try to achieve this.

From the documentation, I am told that this requires a two-step process.
"The web service exposes two sets of add_document(). 1) a two phase add_document. It requires an http post to upload the initial document followed by the web service call to add_document" - I won't mention the 2nd option since it is not suitable.

This requires the following post parameters:
sessionid "
Note: the above information is apparantly wrong - the requirements are actually named "action" and "session_id". This can be checked on the above link to the php.

The first thing I do with my program is connect to the webservice via the SOAP interface and authenticate. This returns a SessionID.
I have also performed sucessfully the second part of the webservices - the add_document function which also uses the SessionID, but this can be done via http GET and is relatively easy.
The upload.php should create a temporary copy of the file and return a filename which is used by the add_document function - i have tested add_document by manually creating the temporary file and using add_document to process it.

What I cant get a grasp on is exactly what the upload.php requires to be uploaded - where exactly do I put the session_id and action(documentname)? It is the structure of HTTP POST that I dont understand. Imagine I am uploading HelloWorld.txt which contains "Hello World" - what would the entire HTTP POST look like? Just substitue my SessionID key with xxx's and i will get the idea!

Thanks for your time!

I will have to look at that tomorrow. I wonder if expects XML or something.
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I have used the code below as a starting point for my HTTP POST. This accepts the session_ID and action - I just need some help in actually uploading the file. xFileName contains a path to the file i.e. "C:\test.pdf"


Public Shared Function PostData(ByVal Session_ID As String, ByVal xFileName As String, ByVal URL As String, Optional ByVal NeedResponse As Boolean = True) As String
        Dim ReturnPage As String = String.Empty
        Dim Uri As New Uri(URL)
        Dim xSession
        Dim Req As HttpWebRequest
        Req = CType(WebRequest.Create(URL), HttpWebRequest)
        Req.Method = "Post"
        Req.ContentType = "application/x-www-form-urlencoded"
        xSession = "&session_id=" + Session_ID + "&action=C"
        Dim sw As New StreamWriter(Req.GetRequestStream)
        If NeedResponse Then
            Dim sr As New StreamReader(Req.GetResponse.GetResponseStream)
            ReturnPage = sr.ReadToEnd
        End If
        Return ReturnPage
    End Function

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I'm currently on vacation so it will be at least Wed. before I will be taking hard looks at this questions.  Sorry.

No problem - I was away for a week which is why it got left for a while! Do you know of any good books or websites describing the format for HTTP POST? in particular sending binary data and form data in a multipart post - it is still the structure of the POST that i am struggling to understand.
Your help has saved me hundreds of hours of internet surfing.


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