How Does the Single Store Xpages work?

Question

I have a number of XPAges design elements that I use in many different databases. If I read the wiki correctly the single store is an all or nothing situation. So I want to create unique design in a database but use the set of reusable XPages element from a single store location. the wiki says: Apart from the "dummy or blank XPage with the same name of the default XPage" in each instance application, does it matter if an 'instance' contains XPage design elements?

No. If SCXD is set on an application all XPages design elements are ignored on the database and the application uses the design elements on the SCXD database.

If this is the case then I have to create databases where probably 75% of the code is reusable but I would have to repeat it (and maintain it) in dozens of separate databases. pity!

Answer 1

XPages and related elements (Custom Controls, SSJS Libraries, Java Code) can be inherited from a specific template like other design elements. So, I would setup a database called, perhaps, "Core Components" (.ntf or .nsf) with a template name of "CoreComponents". Then on the individual elements in the target DB you would set inheritance to be specifically from the "CoreComponents" template. Then the elements that are unique to each database do not inherit from any template. You can then use File-Application-Refresh design to update the elements with specific inheritance and the one which are unique in that database will not get overwritten.

You do need to do a clean build after the refresh, so I recommend that you keep the Core Components database locally or on a different server than the others so that the daily design task will not update them resulting in corrupted xsp elements.

Answer 2

IBM's preferred model for reusing XPage artifacts across multiple applications is to create OSGi plugins that leverage the XPages Extensibility API.

NotesIn9 episode 64 demonstrates how to make an existing Custom Control design element a library component, which can then be used in any app that has the library available, instead of having to copy the design element to each app separately. Any subsequent changes to that component are then applied immediately to any apps that use it when a new version of the library is deployed.

If you truly have "dozens" of apps that all share certain features, but the entire design should not be identical across all of them, then the OSGi model is definitely the way to go.

But why not flip the entire model on its head? Traditionally, we've always put the code and the data in the same place (e.g. same NSF) because it was a pain to access -- and, especially, visually represent -- data in one NSF via code in another NSF. That's not true anymore. Why have dozens of apps just because the data lives in dozens of places? Any data source in XPages can be told where the data lives... you can link a central user interface to any number of "remote" data stores (either different NSFs on the same server, or even databases on other servers).

Red Pill, for instance, takes this to its logical extreme: they deploy one NSF, which acts as a portal to all your data, no matter where that data lives. The ACLs of the various NSFs (and Readers fields) still ensure that users don't pry into data they haven't been granted access to, and they have complex analytics algorithms for determining which data the users will actually care about. But if you have 500 NSFs in the domain, you're not maintaining 500 different code templates... it's literally just 1; but that one user interface is how users find, and interact with, all their data.

You certainly don't have to take this premise to that extreme, but perhaps you could identify, say, 5 apps where the UI and / or business logic is similar (or even identical), but the data just lives in multiple places. Create one central app for interacting with all of that data. Create a "homepage" that gives users a way to select which "app" they're trying to access (or, if they should only have access to one to begin with, compute which one that is), and then once they navigate in to the specific "app", just bind the data sources to the relevant NSF instead of assuming each view or document lives in the same NSF that the code does.

It's still a good idea to be aware of the Extensibility API, not only for the sake of code reusability, but also to understand just how much of the behavior of the platform truly is within our control now -- provided, of course, that we're willing to occasionally write some custom Java code. But if you shift away from the one-to-one mapping between code and data that we've habitually maintained in Domino for so long, I can practically guarantee that you'll prefer this approach... both for the ease of implementation and maintenance, and for the comparative simplicity it offers to end users.

Answer 3

You can combine the template technique and the all-code-in-one-database approach:

Divide the application design into two parts: a data part and a code part.

The data part contains all Notes views. If it's an classic Notes application it would contain also all design elements for Notes client like Forms, Subforms, Frames and so on.

The code part contains all XPages, Custom Controls, CSS, client/server JavaScript libraries, Themes, images, jars and so on.

Put your 75% common code into masterData.ntf and masterCode.ntf.

The application code databases appCodeX.ntf inherit all design elements of masterCode.ntf and contain the additional application specific design elements.

The code from all application templates gets united in allCode.ntf. It inherits all from masterCode.ntf and inherits the additional pieces of code from application templates.

Based on that you create an allCode.nsf.

On the data side you use the classic template way.

From here you have to possibilities:

1. You use Single Copy XPage Design - connect every appData database with allCode.nsf

2. You connect your XPages in allCode.nsf with appData databases

I prefer the latter. You can define in allCode.nsf where all the application data databases are located, e.g. in property documents.

With the approach showed in picture you're still able to separate application easily e.g. in case you want to sell them. You have already a separate template for every single application.