Please see in-line comments: On Fri, 2006-04-21 at 10:22 -0700, Jim Marino wrote: > On Apr 21, 2006, at 9:40 AM, Duong BaTien wrote: > > > On Fri, 2006-04-21 at 08:12 -0700, Jean-Sebastien Delfino wrote: > > > >> This came up on our April 19th IRC chat: > >> > >> For our JavaOne release we are thinking about dropping the > >> Portable Web > >> Application integration approach (also discussed on this list as > >> Shallow > >> Integration). > >> We would only support the SCA Aware Container integration approach, > >> where we configure Tomcat with a custom Host implementation that > >> bootstraps the Tuscany runtime (aka Deep Integration). > >> > >> What do people in the group thing about this direction? any opinions? > >> > >> > > > > 1) I assume that this direct approach can still work with other > > portable > > approach plugins such as Jsf, Spring, Facelets, and Shale all > > together? > > > I think the portable web container approach is something slightly > different (i.e. how to plug into a servlet container using generic > Servlet APIs). Spring and JSF would integrate using different > mechanisms. For spring, we are planning on using our extensibility > mechanism (we are working on that now and will post to the list as > progress is made). JSF should be rather straightforward. SCA local > services map 1:1 to JSF backing beans. There is some factory class > defined by JSF for integrating third-part containers as backing beans > hosts - I forget the class off the top of my head but this is how I > would approach it. Any contributions would be appreciated for this. > Spring has a nice integration with Jsf that we use for DI (except session scope that we must use jsf) org.springframework.web.context.ContextLoaderListener This enables the mixing of Spring bean and Jsf. Please make sure that Tuscany, Jsf and Spring can play well together.
> Also, BigBank has some examples of taglib integration that places > local services in a JSP page context (which can then be accessed by > JSP expressions). > > I don't know much about Shale except that it is some kind of state > machine for UI components. Not knowing more detail, I probably would > do one of the following: > > - just call SCA through ModuleContext.locate in whatever Shale uses > to handle incoming requests and dispatch to services. As long as the > SCA context is set prior to the Shale code is executed (this should > be automatic in Tomcat; in a generic J2EE container it would be a > matter of setting the proper order for Servlet filters). > > - for a more complicated integration, I would look for a plug point > in shale that would allow one dispatch out to SCA local services to > handle incoming requests. This would be similar to JSF. > Shale is just an extension of Jsf and acts as an application controller org.apache.shale.faces.ShaleApplicationFilter to enable seveal additional features at the UI side such as Dialog or remote for ajax. Dialog is just a bean in user session to maintain UI state for conversation longer than 1 request and less than 1 session. It is popped out of the session scope at Dialog exit point. Tuscany has module scope in addition to other standard scopes. It would be nice to have some source of integration to maintain the flexibility of choice and well integrated when used together i.e. co-ordination of state management at both the UI and backend processing. > > 2) Does this approach mean that for every tomcat version, Tuscany > > still > > needs the way it is currently doing? Will the portable way be > > supported > > sometime after JavaOne? > > > Yes we intend to support the portable way. If you would like to > contribute (in order to have it sooner), we would be happy to help > with questions, etc. > > Jim > It is good to hear this for the freedom of mix and match of selected components and features. For contribution, let's see how it turns out based on available time i can devote to it. There are 2 areas i am intended to spend some time: 1) It is nice to turn SCA components into SCA/CoR components using Apache commons-chain so chain features of commands/filters/chains can be part of the component assembly. If Ejb session bean is used as business logic, the beans can be assembled in both SCA and CoR (simple re-usable components without the need of BPEL). Again, chain has its DI, but we can wrap around and use Spring beans. 2) Ejb3 persistence is an important technology. Tuscany will be useful with Ejb3 DAS. Apache OpenJPA is already there. Since entity bean can be Jsf backing bean, DTO is eliminated if all components are in the same server. SCA/CoR business components will drive Jsf entity beans using Ejb3 DAS. The framework does most of the heavy lifting;-) Hope to hear more about these 2 areas. BaTien DBGROUPS > > Thanks > > > > BaTien > > DBGROUPS > > > > > > > > > >>> > >>> [snip] > >>> > >>> Jeremy Boynes wrote: > >>> > >>>> There are two ways we can run as part of a web application: > >>>> 1) Using pure J2EE APIs and running as a portable web application > >>>> 2) Running as SCA module within an SCA aware web container > >>>> > >>>> == Portable Web Application == > >>>> In this mode we want to run as a self-contained application in a > >>>> stock > >>>> web container - all we can rely on are the J2EE APIs and that we > >>>> have > >>>> been granted sufficient privileges to run. > >>>> > >>>> In this mode all classes need to be bundled with or made > >>>> available to > >>>> the web application - all JAR files will be included in WEB-INF/ > >>>> lib or > >>>> WEB-INF/classes, made available as references to JARs in a > >>>> containing > >>>> EAR file, or added to the application classpath using some > >>>> container-specific mechanism. > >>>> > >>>> Application isolation will make it difficult/impossible for > >>>> different > >>>> web applications to share information so each web application > >>>> will be a > >>>> standlone unit, either a subsystem with all module components > >>>> present in > >>>> the application or a single module component. > >>>> > >>>> The runtime can be booted on application startup from > >>>> ServletContextListener. This listener will boot the runtime, > >>>> load the > >>>> system definition, and load the application modules. It can bind > >>>> the > >>>> system or module definitions as attributes in the ServletContext. > >>>> > >>>> Each request needs to be associated with the module context for the > >>>> invoked servlet (in the subsystem case different servlets could > >>>> map to > >>>> different module components). This can be done by a Filter that > >>>> binds > >>>> the appropriate ModuleContext to the Thread for use by > >>>> CurrentModuleContext.getContext(). > >>>> > >>>> Each web-service entry point must be bound so a web-service > >>>> endpoint, > >>>> which if we are using the Axis transport, done by configuring > >>>> the Axis > >>>> servlet. The configuration of the Axis engine can be built > >>>> during the > >>>> bootstrap above and passed to the servlet as a ServletContext > >>>> attribute. > >>>> > >>>> Finally, session expiration needs to be detected and a > >>>> notification sent > >>>> to the runtime. This can be done using a HttpSessionListener and > >>>> may be > >>>> combinable with the ServletContextListener above. > >>>> > >>>> All of this must be configured by the user in their web.xml file > >>>> - a > >>>> little configuration here being the price for portability across > >>>> container. Specifically, the following entries must be added: > >>>> * A <listener> configured to boot the runtime > >>>> * A <filter> configured for the request filter > >>>> * A <filter-mapping> for each path associated with a module > >>>> * A <servlet> for the axis servlet > >>>> * A <servlet-mapping> for the axis servlet > >>>> * A <listener> for session expiration (if not combined) > >>>> > >>>> In this configuration, RuntimeContext is a non-priviledged API > >>>> (it runs > >>>> with the permissions of application) but although it is exposed > >>>> for use > >>>> by these infrastructure artifacts there is still no need for the > >>>> application to use it. We can't stop application code from doing > >>>> so but > >>>> this is not harmful as everything is running with application-level > >>>> permissions. > >>>> > >>>> > >>>> > >>>> == SCA Aware Container == > >>>> To avoid the need for users to explicitly configure their web > >>>> applications to enable SCA, we may be able to integrate the runtime > >>>> directly with the web container. In this mode, the runtime would > >>>> run as > >>>> a privileged extension to the container and would automatically > >>>> configure the SCA environment for a deployed web application. We > >>>> have > >>>> started to do this with Apache Tomcat. > >>>> > >>>> All classes for the runtime would be placed in the appropriate > >>>> location > >>>> for the container (e.g. Tomcat's server/lib) and would not be > >>>> exposed to > >>>> the application. The only access the application would have > >>>> would be via > >>>> the standard SCA APIs. > >>>> > >>>> The runtime would bootstrap with the container, before any > >>>> applications > >>>> were deployed. How this is configured is container-specific - > >>>> with the > >>>> current Tomcat integration we have a specialized implementation > >>>> of Host > >>>> that is activated by specifying the appropriate class name in > >>>> server.xml > >>>> > >>>> When an application is deployed, the container extension detects > >>>> this, > >>>> inspects the application to see if it requires SCA and if so > >>>> configures > >>>> the container as necessary. The user only place the sca.module > >>>> file in > >>>> the application for this to happen - there are no SCA-specific > >>>> entires > >>>> in web.xml > >>>> > >>>> The container will need to configure the same sort of entry- > >>>> points as > >>>> described above but may do so in container-specific ways. For > >>>> example, > >>>> the Tomcat integration adds a Valve to the processing pipeline > >>>> instead > >>>> of a Filter as a Valve has access to internals that a Filter > >>>> does not > >>>> (for example, it is able to attach notes to the request). > >>>> > >>>> For web-services, the extension code needs to examine the SCA > >>>> module and > >>>> make sure all the entry-points are bound. One way it could do > >>>> this is to > >>>> configure a single Axis servlet with a engine configuration that > >>>> maps > >>>> each request to the appropriate entry-point; another is to define a > >>>> separate servlet (or internal equivalent e.g. in Tomcat's case a > >>>> custom > >>>> Wrapper) for each entry-point that is attached directly to the > >>>> entry > >>>> point's context in the runtime. > >>>> > >>>> In this type of configuration, the RuntimeContext is a > >>>> privileged API > >>>> which should not be (and does not need to be) exposed to the > >>>> application. > >>>> > >>>> -- > >>>> Jeremy > >>>> > >>>> > >>>> > >>> [snip] > >>> > >>> > > > > >
