Understanding work
object attachments
|
|
A work object attachment identifies a named file, screen shot image, URL or text note that a user or an activity has associated with a work object.
On the standard harness rule Perform
and Review forms, a paper clip button 
provides access to review or add attachments.
Each work object can have hundreds or thousands of attachments, although by default the attachment report shows a maximum of 100.
The system stores attachments in instances of these concrete classes, subclasses of the Data-Work Attach- class:
Your application can include additional custom attachment types if needed.
By default, work object attachments are stored as rows of
the pc_data_workattach table. Note that
attachments are not stored in the same database table as the
work objects.
When a user designates a file as an attachment, the system copies (uploads) the file and links it to the history of the work object.
The system saves attachments for correspondence stored in HTML format (HTM file type) even if a user edited the correspondence with Microsoft Word. If the correspondence includes embedded images or other embedded objects, the attachment is saved as a ZIP archive (ZIP file type) containing the objects and the HTM file. The system converts the ZIP file internally into characters using Base64 encoding.
The description text (Subject field) of a file attachment is limited to 60 characters.
By default, file attachments are restricted to 25 megabytes
in size. You can set a larger or smaller limit with the
prconfig.xml file setting
<env name="Initialization/MaximumFileUploadSizeMB" value="nn" />
where nn is the size in megabytes.
If a user accesses the Process Commander server with HTTPS
protocol (rather than HTTP), this may block certain download
operations from the server to the workstation. For details and
suggestions, see Pega Developer Network article 
PRKB-17997 Troubleshooting: "Internet Explorer
cannot download " messages (Tomcat with SSL).
URL and URI attachments can provide flexibility and power
while requiring little storage. A URL can point to a document
or file on an intranet or the World Wide Web. A URL can also
cause Process Commander to execute an activity in your
application; the activity can search or retrieve a document or
file, call an external system, and so on. See Pega Developer
Network article PRKB-16586 Linking to
external documents versus importing them as work object
attachments.
At the desktop, a user can capture a screen image of any open window as a JPG file, known as a screen shot attachment. The JPG file is stored internally as characters using Base64 encoding. Use the Advanced View of the standard History and Attachments display to enter screen shot attachments
A user with a scanner attached to her workstation can use the Image Viewer tool to scan documents and attach them as TIFF image files to work objects. The standard Work-.AttachFromScanner local flow action starts this operation. The system converts the TIFF file into characters using Base64 encoding.
Use the Advanced View of the standard History and Attachments display to enter screen shot attachments.
Files received from any source might contain computer viruses. Optionally you can connect your application's processing of work object attachments to an external virus-checking module. Virus checking occurs before the system saves the attachment to the database. Override the standard extension point activity Data-WorkAttach-File.CallVirusCheck to call the checker and modify processing by the flow rule to handle files reported to contain viruses. The virus check module can be a Java routine or (when Process Commander is hosted on Microsoft Windows) in a Windows DLL file.
While the number of attachments you can add to a work object is unlimited, the standard list view rule Link-Attachment.AttachmentList.ALL displays only up to 100 attachments. You can override this rule if necessary.
Process Commander provides two approaches to convert Word DOC files to Portable Document formats. For each approach, the original DOC file and the converted PDF file become two file attachments, typically of separate categories:
To convert in the background:
To convert in the foreground, include the standard flow action .Work-.ConvertAttachmenttoPDF as a local flow action in appropriate assignments in the flow rule. Users must select this flow action, complete the form, and wait for workstation conversion.
You can support attachments with attachment category rules, which can be used to control user's ability to add, view, edit, or delete attachments. For more information, see attachment category.
