3-Tier Upload in ASP

FileUpEE can perform a browser-to-server-to-server (3-tier) upload, allowing you to maintain a secure file server that is isolated from your public web server.

The client-to-server part of the file transfer is a form-based file upload . This type of upload submits form data (the file and/or other form elements) as name/value pairs. FileUpEE processes the upload on the web server.

FileUpEE submits the server-to-server part of the file transfer as a SOAP message with an attachment . SOAP (Simple Object Access Protocol) is an Internet protocol that uses HTTP as its transport and XML as its data format. A SOAP request is submitted in an XML document (the XML payload) via HTTP. Unlike a form-based upload request - which can only include name/value pairs - the XML payload can contain a much richer, hierarchical set of data.

When scripting a 3-tier upload, you can include all upload processing instructions on the Web server, as you would in a client-to-server upload. If the request from web server to file server includes all processing instructions, these can be executed automatically on the file server. Alternatively, you can put the processing instructions on the file server, to protect important paths and database information.

To allow file uploads, NTFS permissions must be set appropriately for FileUpEE's temporary and destination directories. For more information, see Security Considerations.

Uploading a File from Client to web Server to File Server

The following ASP tutorial demonstrates 3-tier uploading with FileUpEE. The tutorial's application uploads a file from a web form. The file is first sent to a Web server, and then to a file server, where it is saved. All upload processing directions (such as the destination directory) are in the web server page. These directions are executed by FileUpEE on the file server if automatic file processing is selected (as it is in the following tutorial).

The Client-Side Code

The client-side page defines a web form that is used to upload the file from the client to the web server. The web form submitting the file must contain:

A <form> ACTION attribute that calls the upload processing script on the server.
The <form> tag attribute ENCTYPE="multipart/form-data".
An <input type="file"> tag, including a name attribute.

The web Server Code

The web server page includes all upload processing directions: the save method (FileUpEE can save to either a directory or a database), save location, and other properties. FileUpEE sends the upload request from the web server to the file server page specified by the TargetUrl property. The upload request from web server to file server is a SOAP message with an attachment. The SOAP request (an XML file) contains all the processing directions specified on the web server. These directions are executed by FileUpEE on the file server if automatic file processing is selected (as it is in the following tutorial).

The following VBScript lines receive the upload on the web server, set instructions to be executed on the file server (the upload's final destination), and send the upload (as a SOAP request) to the file server:

Set oFileUpEE = Server.CreateObject("SoftArtisans.FileUpEe")
Creates an instance of FileUpEE.
oFileUpEE.TransferStage = saWebServer
The TransferStage property specifies the stage of the file upload, that is, the server on which the current code should run. The transfer stage can be set to saWebServer or saFileServer. The TransferStage property is required. Set this property immediately after creating an instance of FileUpEE.

oFileUpEE.ProcessRequest
        Request, False, False

The ProcessRequest method passes the Request object to FileUpEE. The collection of transferred files is not available until after ProcessRequest is called. In addition to the ASP Request object, ProcessRequest takes two boolean parameters:

	SoapRequest

	The `SoapRequest` parameter tells FileUpEE whether the file transfer is a SOAP request or not. Since the web server receives a form-based request and not a SOAP request, `SoapRequest` is set to `false`.
	AutoProcess
	If the `AutoProcess` parameter is set to `true`, FileUpEE will process the Request according to the SOAP payload (the XML document transferred with a SOAP request), and it is not required to "manually" save the files by calling `FileEe.Save` in the script that passes `true` as the `AutoProcess` parameter of `ProcessRequest`. `AutoProcess` can only be `true` if the script is processing a SOAP request. The web server is processing a form-based file upload, not a SOAP request, so `AutoProcess` must be `false`.

oFileUpEE.DestinationDirectory = Server.MapPath("/FileUpEE/Samples/temp")
Sets the directory on the file server in which the uploaded file will be saved.
Set oFile = oFileUpEE.Files("myFile")
Sets a FileEE object which represents the uploaded file. "myFile" is the name of the file input field in the form that submitted the upload.
oFileUpEE.TargetUrl = "http://localhost/FileUpEE/Samples/UploadSamples/Basic/Simple3Tier/ASP/fileserver.asp"
When sending a request from server to server you must set TargetUrl. This property specifies the url of the page on the file server to which FileUpEE will submit the request.
oFile.DestinationFileName = oFile.ClientFileName
The DestinationFileName property sets the name with which to save the uploaded file. In this case, the name is set to the file's original name on the client.
intSAResult = oFileUpEE.SendRequest()
Sends the upload request to the file server's FileUpEE application.

The File Server Code

The file server code does not include upload processing instructions, because it automatically executes the instructions that were set on the web server and sent to the file server as a SOAP request.

Set oFileUpEe = Server.CreateObject("SoftArtisans.FileUpEe")
Creates an instance of FileUpEE.
oFileUpEE.TransferStage = saFileServer
The TransferStage property specifies the stage of the file upload, that is, the server on which the current code should run. The transfer stage can be client, web server, or file server. The transfer stage can be set to saWebServer or saFileServer. The TransferStage property is required. Set this property immediately after creating an instance of FileUpEE.

oFileUpEe.ProcessRequest
        Request, True, True

	SoapRequest

	The `SoapRequest` parameter tells FileUpEE whether the file transfer is a SOAP request or not. Since the file server receives a SOAP request from the web Server, `SoapRequest` is set to `true`. Note that in almost all cases, server-to-server FileUpEE file transfers are SOAP requests.
	AutoProcess
	If the `AutoProcess` parameter is set to `true`, FileUpEE will process the Request according to the SOAP payload (the XML document tranferred with a SOAP request), and it is not required to "manually" save the files by calling `FileEe.Save` in the script that passes `true` as the `AutoProcess` parameter of `ProcessRequest`. `AutoProcess` can only be `true` if the script is processing a SOAP request. Since all upload processing instructions for the file server were included in the web server code, in the file server page `AutoProcess` is set to `true`.

oFileUpEe.SendResponse Response
Takes the ASP Response object and sends it to the FileUpEE application on the web server. Note that the response to the client was set in the web server code.

Avoid Errors by Using Typelibs

In ASP, Typelibs provide quick and convenient access to constants associated with a particular object. The web server script in this example includes FileUpEE's TypeLib because the script uses constants (e.g, saWebServer). The UUID attribute specifies FileUpEE's unique identifier.

<!--METADATA TYPE="TypeLib" UUID="{6B16F98B-015D-417C-9753-74C0404EBC37}"-->

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