I've been working on my workshop for this year's CollabSphere, and one of the main decisions I have to make is what I'm going to focus on. The idea of the workshop is to give a bit more brass-tacks information about how to use the project: rather than just a list of features, it'll be about the specific business of building an app using it.
But how does one build an app in it? There's certainly no lack of tools available, but that leads to the opposite problem: what's the right one for your project? What's likely to be the most common path people take?
The Types
As I've been working on it, I've grouped things into four main categories, and I figured it'd be useful to enumerate them here to coordinate my thoughts and provide some general information. There aren't hard lines between these: you can use any mixture of some or all of the parts in an app, and do different mixes in different apps. These are just what I expect to be the main groupings:
- "XPages Plus", using some new capabilities in existing or new apps with XPages-based UIs
- REST services, focusing on providing REST endpoints for JavaScript-based apps or other servers
- MVC and JSP, focusing on clean, lightweight UIs for document-based apps, but less ideal for complex business logic
- JSF, building the same sorts of apps XPages is adept at, but using newer technology
"XPages Plus"
The first route is how the project got started: you keep building XPages apps but sprinkle in a few new capabilities to improve them.
For example, you could replace your managed beans defined in faces-config.xml with CDI beans, allowing you to get the quick benefit of annotation-based definitions and then the bigger benefits of @Inject, producer methods, and interceptors.
You could also start using newer EL features, like the long-desired ability to pass parameters to methods.
This path wouldn't necessarily require a lot of reworking of your app or changing the way you think about XPages development, but would still be something of a minor development refresh and can set you up well for future improvements.
Your data access will likely still be through the traditional xp:dominoDocument and xp:dominoView components, but you could also write beans that access data with lotus.domino or ODA, or switch to using the NoSQL driver.
REST Services
Alternatively, you could decide you want to focus your apps around REST services with either a JavaScript app in, for example, React as the front end, or providing services to remote servers.
With this, you'd largely stop using XPages design elements entirely, instead defining your services in Java classes with JAX-RS annotations. This brings huge advantages over other ways to write REST services on Domino, with the JAX-RS annotations allowing for clear, logical definition of services, their parameters, and their output. Moreover, the ancillary tooling brings things like automatic OpenAPI definitions, which would be annoying to maintain using things like the XPages-side REST controls.
This path is good if you're specifically aiming to build a JavaScript-based app, either because you just like it, because your organization decided to go that route, or if you have a larger team that splits the duties of front-end and back-end developers. It can also naturally blend into the next one.
Your data access here won't be through the XPages components, but you could still use lotus.domino or ODA classes, or switch to the NoSQL driver. That actually goes for the next two, too, so we'll just count that as assumed.
MVC and JSP
I'll admit that part of the reason I want to consider this a top-tier route is because I just personally really like it. I've had a blast writing apps like this blog and the OpenNTF site using this path, with its much-cleaner code and back-to-basics approach to HTML.
Regardless of my personal enjoyment of it, though, this has some nice advantages. The fact that MVC builds on top of JAX-RS means that it melds well with the REST-services approach above. For example, you might primarily write REST services for a JS app, but then do a set of "admin" pages with MVC. Or you might use this as part of the prototype phase: structure your app the same way you will when you expand to a multi-tier team, but start out by doing a quick UI with MVC on top of the same or related endpoints.
With this path, your app will start with Java classes with JAX-RS annotations, and then you'd mix it with JSP files inside WebContent/WEB-INF. One down side to this approach is that Designer doesn't provide much help for writing JSP files. In the tooling, I bind .jsp and .tag files to the HTML editor, so you at least get normal HTML assistance, but that won't help you with specific JSP tags and EL. Fortunately, the set of tools you'll likely use in JSP is comparatively small, so you'll eventually memorize things like <c:forEach items="..." var="...">...</c:forEach> in much the same way that you could eventually write out an <xp:repeat/> in your sleep in XPages.
JSF
This one, technically tricky though it may be, is conceptually straightforward: write the same sort of apps you do with XPages, but do it with modern JSF instead. This makes a lot of sense, since JSF shares XPages's acumen with complicated forms with partial refreshes and changing state data, but has benefited from some development that didn't happen on the XPages side.
It's not a direct replacement: in particular, JSF has no knowledge of Domino data sources, so there's no xp:dominoDocument or xp:dominoView. You'd still need to do your data access via beans, as in the previous two options, likely using either lotus.domino/ODA or the NoSQL driver. Additionally, Designer really doesn't help you here - again, I map .xhtml and .jsf files to the HTML editor, but JSF components have a lot of properties to set, and so you'll be spending a lot of time referencing documentation.
Still, it's clear why this is proving to be a popular path. The development model is the same as in XPages, while the JSF stack (especially including PrimeFaces) brings a lot of amenities that aren't in XPages and are also more portable to other environments.
Conclusion
So, for now, I'm thinking of splitting up the workshop to cover each of these paths a bit. That runs the risk of feeling like too much of a grab bag, but I don't want to give the opposite impression, that the project only allows for some specific path. It's a broad platform update, accommodating many development approaches, and I want to keep that clear. Fortunately, each path has a pretty-clean pitch, and the shared components (CDI, bean validation, the REST client, etc.) build on each other well, so the idea that it's a pool of features that you can swim in is, I think, compelling.