The Experience manager web service appears to be very similar to a standard Content Delivery web service, while its purpose is apparently just to transmit preview renderings of content to the Preview database. If that's all there is to it, it would require only a simple implementation to accept some data and throw it into a table or two.

Speaking of "a table or two" - the Preview database definitely identical to a normal broker database, as it's created in the same way. If you examine it, you'll find two tables that seem to have anything to do with preview content. So why use a full broker database?

Update: In @AlbertRomkes famous Troubleshooting XPM blog post, he mentions that data gets written to the COMPONENT_PRESENTATIONS table of the preview database.


They deal with very separate concerns; but they do so in an extremely similar manner; my guess is that the session preview deployment functionality was built as an extension of the CD webservice because that was the simplest possible solution (not because from an architectural perspective it is the cleanest, nicest or most logical one).

I suppose if you really want to know how it works you could trace all of the web requests made by XPM to the CD webservice and then create your own mock version of it but such an exercise would potentially require quite a bit of effort and in all likelihood no customer would ever pay for it.

All of this is mere speculation; if you really want to know why this was done in such a way you would need to ask the R&D team at SDL (seeing who posted this question this is preaching to the choir of course...).

  • Various members of the R&D team, and other Tridion "internals" regularly answer questions here. (And several more answer questions now and then.) This is an open question, but I'd certainly welcome any insights coming from there.
    – Dominic Cronin
    Dec 17 '14 at 8:29

CD web service

The "Experience Manager web service" is in fact the Content Delivery (CD) web service with a Experience Manager (XPM) extension. So it is not just very similar, but actually the same thing.

Often the CD web service with XPM etension is called the "preview web service" or similar, I dont like this because this causes the confusion you have.

A similar CD web service extension is used for SmartTarget. It is perfectly ok to have one CD web service with both the XPM extension and SmartTarget extension installed.

Preview database

The preview database stores the preview content, published thought the fast-track-publishing process, using the CD web service (with XPM extension). If you view a preview of a page or DCP this content is temporarily stored in the preview database, after you republish the content it is send though the normal publishing process to the Broker database using the deployer.

I am not sure about those two tables, the db format is interesting but also internal, for me it just works.

  • Yes - it's actually a CD web service with something added. My question is more "Why is it mixed in with the CD web service, when to all appearances, they deal with entirely separate concerns?" Similarly for the database. And sure - "Follow the instructions and it just works" is fine at one level, but I'm trying to reach for a bit of understanding here.
    – Dominic Cronin
    Dec 12 '14 at 8:19

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