hi !
what is your status ?
you already tried somet. out?
at first you should read the readme.txt from from the struts-bridge u have
to use.
after this, this:
http://portals.apache.org/jetspeed-2/multiproject/portals-bridges-struts/features.html
the readme.txt explains the first steps.
good luck and tell us more - if you have any problems....
thomas
the readme.txt:
Copyright 2004 The Apache Software Foundation
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
Apache Portals Struts Framework Bridge:
This is the initial version of a small bridge to allow Struts to be used
as Action handler and context renderer within a portlet.
It's far from complete yet but already the standard MailReader example
application does run nicely under Jetspeed 2.
This demo application can be found under the applications folder in
Jetspeed 2 and is automatically build and deployed with its setup.
Documentation I haven't really written yet (you're looking at all there is
right now) but will be provided as soon as possible.
Overview:
The problem with embedding Struts within a portlet is that Struts
processes action handling and view rendering all in one event.
To be able to use Struts the framework creates a *virtual* servlet
context in which it intercepts the Struts processing after
its action handling and postpones the view rendering to the portlet
RenderRequest.
To be able to do this *right* a Struts portlet application needs to
follow some rules.
Not every Struts application will run out of the box!
A Struts page url within the portlet is encoded as a portlet render
parameter. To be able to target a different page, adapted versions
of the <html:form> and <html:link> tags are supplied (taglib
struts-portlet.tld). These will generated a PortletURL with the target
page correctly encoded as (action) parameter. Other Struts tags will
have to be adapted as well but only these are done for now.
Assumptions, restrictions and features:
All user interactions go through actions. Direct jsp access by the user
will break the framework. This is already *recommended*
for any Struts application so this should be not a big problem. Enforce
this by storing all jsp files beneath WEB-INF.
Struts page url's may not contain '|' or '$' characters. These are
currently used to encode a page url to be able to use it as
a render parameter.
No direct output rendering from an action. All output should be rendered
from an ActionForward after action processing.
After an action the resulting view rendering ActionForward is included,
forwarded or redirected to by Struts. The framework will
intercept this and postpone the actual rendering to the RenderRequest
event of the portlet.
For an include or forward the current Struts context will be temporarily
saved in a StrutsRenderContext object in the session. This
contains the actual render path, the current ActionMapping, ActionForm,
ActionMessages and errors (if defined).
For a redirect just the new Struts page url will be set (note: these
ActionForwards need to point at an action mapping, NOT a jsp).
During a RenderRequest the framework will send Struts once again through
the same processing path but will intercept before it will
actually start checking/validating parameters. It'll then check if a
StrutsRenderContext is available. If so, the context will be
loaded into the request context and the saved ActionForward path will
now be included (forwards are not allowed in portlets). Otherwise
Struts will just continue processing (but won't have any parameters to
process).
The consequence of this solution is that input action chaining isn't
supported (atleat not yet). So action processing realy should be
done in one action only. Furthermore, view rendering should normally NOT
be dependent on request scope input parameters. This is
supported by the StrutsRenderContext (which ONLY saves the ActionForm
and messages and currently NO other parameters or attributes)
but really only meant for handling validation errors and will only work
once (refreshing after a validation error will clear any input
/errormessage). A proper MVC implementation should already give you that
by the way. If input state has to be preserved beyond one
request, session scope ActionForms and ActionMessages stored in the
session (supported since Struts 1.2) should be used.
To get the proper flow, ActionForwards used after a successfull action
processing really should define redirect="true".
Struts will normaly forward back to the error page after a validation
error. The input attribute of the actionmapping is used for that.
But this normally is pointing to a ActionForward directed at an jsp or
pointing to a jsp itself. That won't do using this framework.
Therefore the page url requesting the action is saved by the
struts-portlet tags as well. If after an action processing errors are
found the framework will ignore the input page url but uses its own
saved url.
One thing which this bridge supports while formally this is not allowed
in a portlet is accepting response.sendError() calls. During
ActionRequest processing the error code (and optional message) are saved
in a StrutsErrorContext. When the RenderRequest comes along
an error page will be rendered (currently embedded within
StrutsPortlet). A page refresh will bring up the current Struts page
again.
Futhermore, any non-handled exception will end up on that *catch-all*
error page.
Usage:
- run maven install (default goal so just maven will do)
This will build and install (in your local maven repository) the
portals-bridges-struts-<version>.jar.
This jar has to be put in the WEB-INF/lib of a portlet.
It depends on portals-bridges-common which delivers the
ServletContextProvider interface.
This interface has to be implemented for a specific portal and gives
StrutsPortlet access to the servlet context
its running in. For J2 this has already been done:
org.apache.jetspeed.portlet.ServletContextProviderImpl, and is
globabally available to any J2 portlet (embedded in the
jetspeed-commons-<version>.jar located in Tomcat/shared/lib).
- create/modify web.xml:
Define as action servlet:
org.apache.portals.bridges.struts.PortletServlet which extends
org.apache.struts.action.ActionServlet.
Define an extension mapping for the action servlet (*.do). Directory
mapping is not supported.
- create/modify portlet.xml:
Use as portlet-class: org.apache.portals.bridges.struts.StrutsPortlet
Define the following init-param elements:
- name: ServletContextProvider
value: org.apache.jetspeed.portlet.ServletContextProviderImpl
(or one of your own if not using J2)
required: yes
- name: ViewPage
value: <action mapping> to welcome page like: /welcome.do or
/index.do (note the extension: jsp's won't do)
required: yes
The welcome file list from web.xml is not used!
- name: EditPage
value: <action mapping> to default edit page
required: no, default taken from ViewPage
- name: HelpPage
value: <action mapping> to default help page
required: no, default taken from ViewPage
- name: ActionPage
value: <action mapping> to default action page
required: no, default taken from ViewPage
- Use the right struts.jar and its .tld files. The framework currently
has been tested against version 1.2.1.
- The struts-portlet.tld is included in the struts-portlet.jar so you
can refer to it directly from within jsp files
using something like <%@ taglib
uri="http://struts.apache.org/tags-portlet"; prefix="sp" %>.
- modify struts-config.xml:
Define as controller processorClass:
org.apache.portals.bridges.struts.PortletRequestProcessor.
Note, tiles usage isn't possible yet (probably won't be difficult to
support so maybe soon).
- replace all struts tags which generate action urls:
The struts-portlet.tld currently contains adaptions for <html:form>
and <html:link>. Others will need to be provided later.
These adapted tags ensures the correct portlet url's will be
generated.
- replace remote javascript retrieval ( <javascript src="url"/> with
<struts-portlet:script src="url"/> for the same reason
as above.
- setup the actions and mappings with respect to the above mentioned
assumptions and restrictions.
Demo:
As example implementation and proof of concept the Struts MailReader
example application (from version 1.2.1) is
converted to a Struts Portlet.
The example has been modified on the following points:
- all jsp files and the tour.html are moved below WEB-INF in folder
view.
- the <html:form> and <html:link> tags are replaced by their
struts-portlet versions
- the remote javascript tags (for validation) are replaced by the
struts-portlet script tag
- the welcome file index.jsp is removed (not needed anymore and did
issue an illegal forward anyway)
- the CheckLogonTag has been removed:
This one issued an illegal forward when the user wasn't logged on.
Besided being *bad* practice to do flow control during
view rendering having moved the jsp files below the WEB-INF now
enforced action processing anyway so the check is done now
appropriately there.
- The struts-config files (there are two) are modified according the
above rules.
- Logoff doesn't invalidate the session anymore which could interfere
with other portlets within the same application.
As the demo is configured for deployment under Jetspeed-2 a
ServletContextProvider implementation is already available at runtime (see
above).
To get it running under a different portal an implementation for
ServletContextProvider has to be provided. If its not
delivered by the portal itself you can try to define one yourself and
include it in the demo.
20040729, Ate Douma
"angeloimm" <[EMAIL PROTECTED]>
18.04.2005 12:26
Please respond to "Jetspeed Users List"
To: "Jetspeed Jetspeed" <[email protected]>
cc:
Subject: Jetspeed-2 Struts application as a portlet
Hi all; i have downloaded and rebuilded successfully Jetspeed-2; i have
seen some samples; in these samples there was the struts portlet but i
have some confusion.... can anybody tell me or show me how i can configure
a my struts application as a Portlet under Jetspeed-2 portal engine?
Thanks.
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