xpages: how do attachments work in a web page

Question

The context here is that, in a CMS type of app, the users that create content like to reproduce Notes' way of having attachments anywhere in the text, not just a list of attachments at the bottom of the page. When creating a page, they want to be able to create links to the attachments right away, using a link and an img tag, not saving the document first and then edit it again.

I have found the YouAtNotes HTML5 Multi File Upload control, which enables the users to upload the attachments before the document is actually saved. The URL for attachment uploaded befor ethe doc is saved is then:

http://myserver/myDB.nsf/xsp/.ibmmodres/persistence/DominoDoc-NEW_569-Body/indifference.jpg

I use this URL in the CKEditor to create an image and it looks OK: the image shows up in the editor and has this URL:

/myDB.nsf/xsp/.ibmmodres/persistence/DominoDoc-NEW_569-Body/insanity.jpg

I then save the document, and it still looks good. The image is showing up and the URL is still:

http://myserver/mydb.nsf/xsp/.ibmmodres/persistence/DominoDoc-NEW_569-Body/indifference.jpg

I close my browser, and open up the page again, and now I see that my image is not showing up, but the URL is still:

/Belair/xBiblio.nsf/xsp/.ibmmodres/persistence/DominoDoc-NEW_569-Body/indifference.jpg

But if I look at the URL that is used by the download control, this is what is has:

http://myserver/mydb.nsf/xsp/.ibmmodres/domino/OpenAttachment/belair/xbiblio.nsf/E4E384094564EE9E85257F33005953AE/Body/indifference.jpg

Why did it change?

Is there documentation on how that whole attachmentprocess works, so I can understand it and give proper indications to the users so they can create valid links.

We also have a particularity in our publishing code: we need to keep the UNID of the published document so links that were made using UNIDs are still working. It is an app with a lot of content and many external apps link to it. So when we publish, we actually copy all the content of the draft into the already published document, so the UNID is different from the draft document, and we have issues with attachment links because of that. But that is something else...

Answer 1

The URL "/Belair/xBiblio.nsf/xsp/.ibmmodres/persistence/DominoDoc-NEW_569-Body/indifference.jpg" relates to a temporary location before the docment has been saved. This is standard functionality because

1. For SSJS / Java to save an file into an NSF, it's got to have been uploaded to the server prior to the commit.
2. The user has not chosen to save the file yet, so it shouldn't be added to the NSF.
3. The document hasn't been saved yet, so even if it should be saved to the NSF, no document yet exists to save it to.

The components of the URL are:

• "/Belair/xBiblio.nsf", the URL of the database it will finally need to be committed to.
• "xsp/.ibmmodres/persistence", a URL that corresponds to a physical folder location where temporary files for this NSF are stored, based on xsp.properties of the NSF; if nothing is defined in xsp.properties of the NSF, xsp.properties of the server is used; if nothing is defined there, a default location is used.
• "DominoDoc-NEW_569", a temporary reference to the new, unsaved dominoDocument datasource. If you close the browser and re-open it, you'll be getting a different temporary dominoDocument datasource reference, so I wouldn't expect the image to show up. Otherwise, different users could get one another's attachments.
• "-Body", the field the file needs saving into.
• "/indifference.jpg" the file name.

Once the document is saved, the file is stored into the Body field of the relevant document, and the file system cleaned up. The URL has to change, because otherwise the attachment would not be available on other replicas, because only the database gets replicated, and it could not be managed by DAOS.

The new URL "http://myserver/mydb.nsf/xsp/.ibmmodres/domino/OpenAttachment/belair/xbiblio.nsf/E4E384094564EE9E85257F33005953AE/Body/indifference.jpg" corresponds to:

• "myserver/mydb.nsf/xsp/.ibmmodres/domino/OpenAttachment", shorthand URL to open the relevant attachment.
• "/belair/xbiblio.nsf/E4E384094564EE9E85257F33005953AE", the location of the document the attachment is stored in.
• "/Body", the field name.
• "/indifference.jpg", the attachment name (the field could have multiple attachments, of course).

The information above is based on what has been documented in XPages Portable Command Guide (for xsp.properties settings for changing the default temporary locations) and Mastering XPages 2nd Edition.

I'm not sure what the YouAtNotes uploader does, so I can't say whether it should be changing the URL or not on save. But in more recent versions of Domino, attachments can be uploaded without a full refresh, which may be of use as an alternative.

When you're copying documents, if you're storing HTML that references images by their URLs, including UNIDs, you'll need to modify those references.

If you want to keep UNIDs, remember that they are read-write - you can set them as well as get them. However, bear in mind that you'll have problems if you change the URL to the same URL of an existing document. Bear in mind this is also XPages, so the data accessed via the XPages applications don't have to be in the same database.