Hi Viral Ideally there should be one stateless session bean within action class and business component EJBs so that you have only one remote call and all other EJB calls are local. You should always program considering different tiers on different machines, although you are using the web and app tier on same machine now. Let me know what do you think on this.
Shashank S. Dixit Software Analyst. Datamatics Ltd. Contact: 28291253 ext 146 Mobile: 9820930075 Be brave against all odds. Never give up. -----Original Message----- From: Viral_Thakkar [mailto:[EMAIL PROTECTED] Sent: Thursday, August 21, 2003 9:40 AM To: Struts Users Mailing List; Piper, James D CECOM SEC EPS Subject: RE : Remote and local EJB Thanks Jim. I am using the oracle 9iAS. I also developed the EJB which supports both remote and local access. I am also able to invoke this EJB from my action class. I accessed this EJB using the remote and also using local interface separately. The reason why I want this EJB to be deployed both as local and remote is that at present EJB will be accessed by the struts action class, both are in same JVM so I can access the EJB using the local interface. In future when we do clustering then at that time, EJB bean may be at different server, in different JVM, at that time struts action class should dynamically find the remote EJB. One way I think, we can handle such situation in the catch block of the NamingException() while accessing the local bean, we need to lookup the remote EJB. But it seems that this is not the good programming practice. So I am looking for some design pattern or framework, which supports the solution to this problem. Thanks, Viral -----Original Message----- From: Piper, James D CECOM SEC EPS [mailto:[EMAIL PROTECTED] Sent: Wednesday, August 20, 2003 7:49 PM To: Viral_Thakkar Subject: RE: RE : Remote and local EJB So let me see if I understand what it is you are wanting to accomplish. It sounds like you have a bunch of EJBs, a Struts application and several servers. You would like http requests coming in to be 'evaluated' by your application and then based on some information within that request (i.e. users name, users ip address, users browsers type, users preference selection, or possibly even the current servers load) invoke either a local or a remote EJB. For example maybe you have an EJB that does some realy heavy calculatations like a ray-tracer and for some important users you want the results to come back faster than for other less important users. So you make your ray tracing EJB and deploy it on both the local server (i.e. the same one running your Struts app) and on some other EJB server far far away. Then register them both in your ejb-jar.xml with different names ie. RayTraceLocal and RayTraceRemote. So now to access either the remote or the local EJB depending on the request you write your Struts action class to first evaluate the HTTP request to figure out if this request is coming from the important user or not and then as appropriate either do your jndi lookup for the RayTraceLocal or the RayTraceRemote. As far as I know there is not any built in mechanics within Struts for doing this kind of thing, its up to you to write an Action class that invokes the backend EJB you want. I think some EJB servers give you some flexability and increase performance when using EJBs that are within the same container - WebLogic I know lets you specify both a remote and a local name for each EJB then provides better performance when using the local one - Possible even the high end WebLogic stuff will do automatic load balancing between EJB server so that your calls to jndi lookup return references to EJBs on whatever server is being currently used less. But these kind of load balancing issues you would need to talk with your EJB server provider and then build your Struts actions to invkoke those EJBs in the way the EJB server provider specified to get the benefits of load balancing. Good Luck, Jim Piper -----Original Message----- From: Viral_Thakkar [mailto:[EMAIL PROTECTED] Sent: Wednesday, August 20, 2003 8:27 AM To: Struts Users Mailing List; [EMAIL PROTECTED] Subject: RE : Remote and local EJB Thanks for the reply. I agree with this solution, but this does not solve the problem of accessing the remote and local EJBs depending on the request. -----Original Message----- From: Laurent MARQUEZ [mailto:[EMAIL PROTECTED] Sent: Monday, August 18, 2003 10:11 PM To: 'Struts Users Mailing List' Subject: RE : RE : Remote and local EJB 1-See on http://www-106.ibm.com/developerworks/java/library/j-ejb1022.html for pattern business delegate. 2-You must declare your EJB Local or remote or both interface in your web.xml, Like this foo example: #ejb-ref> # <ejb-ref-name> # ejb/fr.artal.FooHome # </ejb-ref-name> # <ejb-ref-type> # Session # </ejb-ref-type> # <home> # fr.artal.FooHome # </home> # <remote> # fr.artal.Foo # </remote> # <ejb-link> # FooEJB # </ejb-link> # </ejb-ref> 3-Call your delegate interface, in your action class: import org.apache.struts.action.Action; #Public class FooAction extends Action #{ # //~ Static fields/initializers --------------------------------------------- # # public static final String ID = "ID"; # public static final String NAME = "NAME"; # # //~ Methods ---------------------------------------------------------------- # protected ActionForward execute( # ActionMapping mapping, # ActionForm form, # HttpServletRequest request, # HttpServletResponse response) # throws Exception { # # Integer id = null; # FooData fooData = null; # # if (form != null) # { # // using the form displayed in the view to get the foo id # String id = (String)PropertyUtils.getSimpleProperty(form, "id"); # # # // using business delegate pattern to interface with EJB session # FooDelegate FooDelegate = new FooDelegate(); # # # fooData = FooDelegate.getFoo(id); # } # if (fooData != null) # { # // set the request attribute # String name = fooData .getName(); # # request.setAttribute(ID, id); # request.setAttribute(NAME, name); # } # } #} 4- you can now, use the request object to display all the foo fields in your view(JSP) Example foo data: #<%@ taglib uri="/WEB-INF/struts-bean.tld" prefix="bean" %> #<%@ taglib uri="/WEB-INF/struts-html.tld" prefix="html" %> # #<html:html> #<head></head> #<body> # #<table width=500 # border="0" cellspacing="0" cellpadding="0"> # <tr> # <td>Foo:</td> # </tr> # <tr> # <td> Id: <%= request.getAttribute("ID") %></td> # </tr> # <tr> # <td> </td> # </tr> # <tr> # <td> Name: <%= request.getAttribute("NAME") %></td> # </tr> # <tr> # <td> </td> # </tr> #</table> #</body> #</html:html> -----Message d'origine----- De : Viral_Thakkar [mailto:[EMAIL PROTECTED] Envoyé : lundi 18 août 2003 11:39 À : Struts Users Mailing List Objet : RE: RE : Remote and local EJB Business delegate pattern explains on how to use the business delegate class. This pattern explains its usage and benefits. Here I am interested in a solution which supports remote and local EJB access depending on request. Any idea on this...??? -----Original Message----- From: Laurent MARQUEZ [mailto:[EMAIL PROTECTED] Sent: Monday, August 18, 2003 1:07 PM To: 'Struts Users Mailing List' Subject: RE : Remote and local EJB Yes, you can interface EJB with Jakarta Struts I use the pattern business delegate See chapter 13 Of Programming Jakarta struts -----Message d'origine----- De : Viral_Thakkar [mailto:[EMAIL PROTECTED] Envoyé : lundi 18 août 2003 07:35 À : Struts Users Mailing List Objet : Remote and local EJB Is there any struts support or any one has idea on following problem? I am developing an application in which I require to develop an EJB with local and remote interface. Local or remote EJB should be invoked depending on the request. How one can identify this? Any framework which support this local and remote EJB development and access? -----Original Message----- From: Robert Leland [mailto:[EMAIL PROTECTED] Sent: Monday, August 18, 2003 9:39 AM To: [EMAIL PROTECTED] Subject: [Validator] The Validator Wiki needs you ! There is now a Commons Validator Wiki ! Beware this is only a shell to start collecting tips, FAQs, and examples for using validator. You can make a much needed contribution ! http://nagoya.apache.org/wiki/apachewiki.cgi?ValidatorProjectPages This is also great opportunity to delete all those old emails you have been saving ! Come on, there must be hundreds, and put them on the web ! Then they are instantly available from any web browser: * At work, Your Desk Your Co-worker's Desk * At home * At a remote site * Even from that better paying job you have been waiting for ! 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