Upload

Prerequisites

• Upload is only supported in DWA using the servlet based Web Server Component.
• The web server and the application server must both have access to the same folder on the file system where the uploaded files can be stored.

Background

The figure below shows the steps involved when a upload request is sent to a Websydian application.

Figure 1: Flow for an upload request

1. The browser sends a request to the web server including one or more files to be uploaded to the server.
2. The Web Server Component servlet saves the files to a folder (configured in the property file).
3. The Web Server Component servlet sends information about the files to the application service.
4. The application service uses a service function to retrieve the information about each file (including the filename).
5. Using the information from the previous step the application service then reads and processes the files. If the file should be preserved for later use the application service must copy/move it to another location.
6. The application service creates a response page to the user (by calling a page generator function).
7. The Web Server Component servlet deletes the file created in step 1).
8. The response page is sent to the browser.

Steps for Implementing Upload

Web Server Component servlet

Upload must be enabled in the Web Server Component servlet. This is done by setting the following properties in the property file:

Application service

To enable upload for an event handler function apply the following steps:

1. Create a text field and insert it in the WebInput variable. For convenience the field can inherit from WSYBASE/FormFieldName, but this is not necessary. The only requirement is that the field is of type Character and is long enough to contain its own implementation name.
2. In the edit point '0 call to build of document' insert a call to the function WSYUTIL/GetUploadedFilesInfo. Map with the field in step 1) and WsyBase<ConnectionPointer>
3. GetUploadedFilesInfo will return the information displayed in the table below.

   Output field	Description
   OriginalFilename	The original name of the file.
   ContentType	The content type of the file. This field will be blank if no content type was supplied by the client.
   Charset	The character set encoding used in the file. This field will be blank if no character set information was supplied by the client.
   UploadedFile	The name of the temporary file stored by the Web Server Component. If no file was uploaded this field will be blank. The file is stored in the folder specified by the Web Server Component servlet property servlet.upload.tempfolder (see Web Server Component servlet for more information).

   Please note that the temporary file returned in the field UploadedFile will be deleted immediately after the request has been processed.

   So if you want to keep the file it must be moved/copied to another location.

   Use the information above to process the file.
4. The event handler must then call a page generator function which generates a response page to the user.
5. Generate and build the page generator, the scoped event handler, and the document template generator functions.
6. After executing the document template generator change the created input field in the template from type TEXT to type FILE.
   The line to be changed will look something like this:
   <P>Upload file<INPUT TYPE="TEXT" NAME="WU6A" VALUE="/(WU6A)" MAXLENGTH="128" SIZE="64"></P>
   In the above line change TYPE="TEXT" to TYPE="FILE".
7. In the template add the attribute enctype="multipart/form-data" to the FORM that contains the input field in 4). E.g:
   <FORM ACTION="/app" NAME="D7UPLEVN" METHOD="POST" enctype="multipart/form-data">

If you want to upload more than one file in one request you repeat step 1 to 6 for each file you want to upload creating a new field in WebInput for each uploaded file.