Rickard, These are great, I've placed them on the Wiki (Which is now linked from the main site, yay!).
-Pat ----- Original Message ----- From: "Rickard Ã-berg" <[EMAIL PROTECTED]> To: "WebWork" <[EMAIL PROTECTED]> Sent: Friday, January 10, 2003 1:59 AM Subject: [OS-webwork] XWork: core concepts > All, > > Since quite a few of you disagreed with my resignation as XWork > architect, I've given some thought to how it would be possible to merge > my requirements with those that you have. It might be possible to do it, > and if so I would reconsider re-starting my work on XWork. I'd like to > begin with defining the core concepts that XWork would have, and also > briefly list my requirements, and see what your thoughts on them are. > > The core concepts that I think must be included are the following: > * Actions. These are the application implementations (generic or > specific) that together define the behaviour of the application. No news > here. > > * Interceptors. These are cross-cutting concerns that apply to several > actions, and which may modify the behaviour of it, produce some > side-effect to the execution of the Action, or modify the input or > output of the Action. > > * Components. This is a new concept for WebWork. Instead of just having > a bunch of non-related Action's, one would bundle some of them together > into a Component. An Action may be part of several Components though. > The main feature of a Component is to function as a state machine which > determine what Action to execute during a page rendering. > > * Packages. Also a new concept. There are usually two approaches to > configuration: coarse-grained or fine-grained. In the coarse-grained > style a setting applies to EVERYTHING in the app. In the fine-grained > style each part needs to be individually configured. The first focus on > ease-of-use and the latter on flexibility. Packages allow for something > in between. An Action, Interceptor or Component can be defined in a > Package and can easily refer to one another within that package. By > having hierarchical packages can easily refer to definitions in other > Packages. For example, we would most likely define a number of Actions, > Interceptors and possible Components that are in a "default" Package, > which user Packages would then depend on. However, user Packages could > then override any such definition made higher up. This gives the > ease-of-use of a coarse-grained configuration together with the total > control and flexibility of a fine-grained configuration, while still > providing reasonably clear semantics. > > These are the core concepts that I can think of. Now, for my own > portlet-ish needs (which I hope will be more common for others too in > the future) the following applies: > * Actions and Components, and their resulting views, are ALWAYS called > through a servlet include. This means that the URL in a browser NEVER > reveals that XWork is used. For example, an admin app would consist of > an admin.jsp which includes the Actions/Components needed for that app. > Not only does that make it easy to extend the admin app later on with > more "portlets", it also makes it possible (for those who are so > inclined) to use J2EE declarative security very easily. Plus bookmarks > are human-friendly. This means that the dispatcher would explicitly > disallow Action invocation that are NOT a result of an include. This too > adds some extra security, since only actions that YOU decide should be > called are actually callable. Plus, your actions can decide much better > in what order they are called, depending on your app requirements. The > actual include would still be using the ".action" extension though. > > * For many simple portlets an include of a .action is fine. For complex > portlets that require a state machine this is not ok. Instead, what one > usually wants is to include a "component" that then delegates to some > action depending on the *state* of some automata. This is similar to how > the CardPane works in WebWork. Essentially, XWork would include this > kind of state machine as a built-in concept instead of as an "add-on" > like CardPane, since this is such an important and common case. It needs > to be as simple and flexible as is possible. When a component renders > its view it also creates URL's that define what the possible next states > are. This means that the URL's in the generated HTML are shortlived > (i.e. after one of the URL's have been clicked they are all invalid), > which also means that it will be impossible to have a double form > submit. After the first submit the URL will be invalid, so clicking > again will not lead to a re-execution of the action. This also gives > some extra security. > > * The execution of a Component (and maybe Action's too) needs to be > split into two phases. The actual execution of an action is done at the > *beginning* of a page render, and the rendering is done at the time of > the include. Why? Because the action may influence what is shown on the > page, and may also result in a redirect to another page. If the action > execution is done at the point of the include it's too late to do a > redirect, and other portlets may have rendered state that is then > changed by the action execution. (This thinking, by coincidence, mirrors > well how the portlet API will work) > > * When rendering URL's, the parameters need to be namespace'd in order > to allow several portlets to happily live together on a page. I.e. > instead of having ?foo=bar one could have ?1.foo=bar&2.foo=bar. The > XWork servlet dispatcher would then at execution filter out those > parameters which does not apply to the action/component/portlet being > executed, and only the remaining parameters are applied using the setX() > initialization code. This requires the rendering code to use either a > taglib (in JSP) or some JavaBean (in Velocity) which can do this > encoding. I know that for *some* applications this will be overkill, but > for those of use who are going beyond very simple web apps it is a > definitive must. > > Off the top of my head, those are the concepts and requirements I have > in order to be able to use XWork in our portal/CMS application. So, what > do you think? > > /Rickard > > > > ------------------------------------------------------- > This SF.NET email is sponsored by: > SourceForge Enterprise Edition + IBM + LinuxWorld = Something 2 See! > http://www.vasoftware.com > _______________________________________________ > Opensymphony-webwork mailing list > [EMAIL PROTECTED] > https://lists.sourceforge.net/lists/listinfo/opensymphony-webwork ------------------------------------------------------- This SF.NET email is sponsored by: SourceForge Enterprise Edition + IBM + LinuxWorld = Something 2 See! http://www.vasoftware.com _______________________________________________ Opensymphony-webwork mailing list [EMAIL PROTECTED] https://lists.sourceforge.net/lists/listinfo/opensymphony-webwork
