Application scoped objects in a cluster

Hi -
          Will weblogic clustering provide failover for Application scoped
          objects (in the ServletContext)? I've read through most of the
          documentation, and it doesn't mention anything. Also, the servlet 2.3
          spec says
          "Context attributes are local to the VM in which they were created.
          This prevents
          ServletContext attributes from being a shared memory store in a
          distributed
          container. When information needs to be shared between servlets
          running in a
          distributed environment, the information should be placed into a
          session (See
          Chapter SRV.7, “Sessions”), stored in a database, or set
          in an Enterprise
          JavaBeans TM component." (Section 3.4)
          However, it doesn't mention anything about failover.
          We have lots of application scoped objects that will need to failover
          somehow - anyone have experience with this?
          Thanks,
          Scott

Hi Scott,
          The application scoped objects (ServletContext) are per Web Container as
          explained in the spec. When the server hosting that Web Container dies, so
          too do the objects in the ServletContext.
          If you are looking something like ServletContext that is replicated across
          the cluster and supports failover, you should check out our Coherence
          product at http://www.tangosol.com/ -- that is exactly what it does.
          Peace,
          Cameron Purdy
          Tangosol Inc.
          Tangosol Coherence: Clustered Coherent Cache for J2EE
          Information at http://www.tangosol.com/
          "Scott Gilpin" <[email protected]> wrote in message
          news:[email protected]...
          > Hi -
          >
          > Will weblogic clustering provide failover for Application scoped
          > objects (in the ServletContext)? I've read through most of the
          > documentation, and it doesn't mention anything. Also, the servlet 2.3
          > spec says
          >
          > "Context attributes are local to the VM in which they were created.
          > This prevents
          > ServletContext attributes from being a shared memory store in a
          > distributed
          > container. When information needs to be shared between servlets
          > running in a
          > distributed environment, the information should be placed into a
          > session (See
          > Chapter SRV.7, “Sessions”), stored in a database, or set
          > in an Enterprise
          > JavaBeans TM component." (Section 3.4)
          >
          > However, it doesn't mention anything about failover.
          >
          > We have lots of application scoped objects that will need to failover
          > somehow - anyone have experience with this?
          >
          > Thanks,
          > Scott

Similar Messages

Is Weblogic Cluster supports Application scope Objects?

          Our Application is mainly depends on Application scope objects. On one m/c, it
          is perfect.
          Now, we want to support the failover , load balancing ... (High Availability).
          I know, weblogic cluster supports HttpSessions, EjbObjects ... etc. What about
          Application scope objects.
          we are planning for weblogic server which supports the our requirements.
          If not, what is the solution to make it work by using Weblogic server.
          for eg: I can give what type of application we are developing --- similar to
          textchat.
          our application is real time application.


Even a singleton is not good enough as singletons are good only in the VM they were
          created it. One way is to have a distributed object such as a stateful session bean of
          which only one instance exists. U can create it at startup and store its handle in
          some persistent storage as well as a singleton. This ensures that even if the
          singleton doesnt contain it the refgerence to it can be obtained.
          There will be some problems with this setup as people should not allow it to create
          instances of it . Any such endeavor will lead to a CacheFullException.
          But essentially that seems possible.
          Even the 2.3 Servlet specification mandates that ServletContext and Application level
          object is only valid inside the JVM which created it. HttpSessions are replicated
          SessionContexts are not and are not likely to be in any J2EE application server
          Sameer
          Devi wrote:
          > One more comment from my side,
          > U mentioned "EXCEPT FOR JNDI" , if this is possible, how can we acheive?
          > Can U give brief description ? Take textchat example itself? since, our application
          > is almost have same mechanism. If it is < 1 sec delay means acceptable for this
          > release.
          >
          > Thanks,
          > Devi
          >
          > "Cameron Purdy" <[email protected]> wrote:
          > >Weblogic doesn't support replicated / synchronized app scope objects
          > >across
          > >a cluster except for JNDI, which is probably not a good solution for
          > >what
          > >you are describing.
          > >
          > >If you need a real-time shared fault-tolerant fail-overable high-performance
          > >load-balanced high-scale data store, then let me know when you find one
          > >;-)
          > >.... seriously, there are not a whole lot of good general purpose solutions
          > >in this space. There are some things to look at but they are all expensive:
          > >
          > >Persistent PowerTier on top of Oracle - a caching entity EJB server
          > >Jasmine (or whatever it is called this week) - an object oriented
          > >distributed data store
          > >....
          > >
          > >Peace,
          > >
          > >--
          > >Cameron Purdy
          > >Tangosol Inc.
          > ><< Tangosol Server: How Weblogic applications are customized >>
          > ><< Download now from http://www.tangosol.com/download.jsp >>
          > >
          > >
          > >"Devi" <[email protected]> wrote in message
          > >news:[email protected]...
          > >>
          > >> Our Application is mainly depends on Application scope objects. On
          > >one
          > >m/c, it
          > >> is perfect.
          > >> Now, we want to support the failover , load balancing ... (High
          > >Availability).
          > >>
          > >> I know, weblogic cluster supports HttpSessions, EjbObjects ... etc.
          > > What
          > >about
          > >> Application scope objects.
          > >> we are planning for weblogic server which supports the our requirements.
          > >>
          > >> If not, what is the solution to make it work by using Weblogic server.
          > >> for eg: I can give what type of application we are developing ---
          > >similar to
          > >> textchat.
          > >> our application is real time application.
          > >>
          > >
          > >

Defining application-scoped work manager in Plan.xml

I am having trouble getting my MDBs to recognize work managers that I have defined in my deployment plan using the admin console.
The work managers show up properly when I click the deployed application and go to the Deployments->myapp.ear->Configuration->Workload tab. They do not show up, however on the Deployments->myapp.ear->Monitoring->Workload tab.
Also, when the server boots, I get a log message like this:
<BEA-002919> <Unable to find a WorkManager with name FaxErrorQueue. Dispatch policy FaxErrorQueue will map to the default WorkManager for the application care360-backend-app-2008>even though FaxErrorQueue shows up under Configuration->Workload.
BACKGROUND
I am upgrading an 8.1 wls to 10MP1. Our MDBs are deployed as a single jar, included in 2 separate ears, which are deployed to 2 separate clusters. So, if we have 2 clusters with 2 managed servers in each cluster, we deploy each MDB to all 4 servers. We control the Execute Queues for each server in 8.1 with different values so that MDB#1 might have a single thread in one managed server and zero execute threads on another. Using the deployment plan is the only way I can think of to implement this. We would prefer not to use the 8.1 emulation, as the deprecated execution queues will have to be dealt with eventually. I am open to any other approaches to accomplish this as well.
Thanks,
Joe

Hello Fred,
Thank you very much for reply.
I totally agree with you but in my scenario, I have multiple domains on a single box.
and I am afraid that there could be a situation where one bad application of a particular domain may take most of the CPU usages.
What I can do is: I can define max thread constrain to all the applications of all the domains but it is not acceptable bcz we have hundreds of applications per domain.
So what I want is: to define some kind of thread constrain at the domain level [so that I can have CPU usages allocated to every domain] as well as some kind of thread constrain to few applications [non prioritize].
I tried this by defining Global Work Managers & Application-scoped Work Managers but I found that applications only respect to Application-scoped Work Managers.
or if I have some kind of way that make sure certain percentage of CPU usages is allocated to a particular domain?
hope I have made my self clear.
Thanks,
Qumar

Application scoped WorkManager

We have an application (.ear) which has two web apps (war's). We want to setup workmanager with max-threads-constraint for both the application. I was able to create application scoped workmanager through deployment descriptors However, I was not able to set the thread count other than the default (-1).
Note: The application (.ear) is targeted to a cluster.
Here is the snippet of the workmanager that I created in the weblogic.xml
<wl-dispatch-policy>workmanager-app1</wl-dispatch-policy>
<work-manager>
<name>workmanager-app1</name>
<max-threads-constraint>
<name>max-app1-threads</name>
<count>30</count>
</max-threads-constraint>
</work-manager>
Please let me know if any thing is wrong in the work-manager configuration. Any pointers on this is highly appreciated.

I need a mechanism to limit one of the webapp to use not more than 30 threads and the second webapp not more than 10 threads while targetting to the same cluster.

How to keep an application level object running with SunIDM?

We are working on intergrate a gmail project with SunIDM. We need an application level object running with SunIDM so it will maintain a token generated from Gmail side. In anther servlet project, I had this object saved in the attribute of the ServletContext, then other session level servlet could share this attribute anytime. Is there a way to store attribute in Servlet Context and have it shared by different user session in SunIDM? I have been reading documents and searched this forum, haven't find any topics related how to maintain an application level object live. Hopefully that I can get some hint here.
Thank you so much.

Paul, Thank you so much for the further explaination. I don't think it will work since the token generated from gmail will expire every 24 hours.
We are using the gdata library published from by gmail people, and I create a new UserService object and have it run in the application level. The UserService object will generate a token and renew it every 24 hours behind the scene. Here is how I implement it in my Servlet project:
//to have a UserService object running at the application level:
public class GmailUserService extends HttpServlet {
public void init(ServletConfig config) throws ServletException{
super.init();
userService = new UserService(myApplication);
config.getServletContext().setAttribute("gmailUserService", userService);
//to access this UserService object from other servlet in each user session:
UserService userService = (UserService)servletContext.getAttribute("gmailUserService");
Gmail will trigger an error if we create a new UserService object for each user. They recommend to have all the user to share one UserService object. I am looking for similar approach in SunIDM.
Thank you again, Paul, for trying to help.

HAP_Document BSP Application "Enter Objective Here "

HI All BSP Expert and PMS Expert.
BSP Standard application "HAP_DOCUMENT" Copy as a Z application. In Standard application "Enter Objective Here" Coming As Label but In Z Application i had changed as Input Field , That Input Field Values it Does not save to R/3 System.
So , Please it is urgent , Suggest me How to save that value to R/3 System.
IF you have any document Related To this Query Please Mail Me.
id : pappu21198mehta @ gmail.com
Thanks & Regard.
Pappu Mehta.

No need to email you the document related to this query. You can find it right [here|http://wiki.sdn.sap.com/wiki/display/HOME/Rules%20of%20Engagement?bc=true].
Cheers
Graham Robbo

Import budget by using DTW, error message "cannot find this object in B1 application defined, object defined error 65171

Dear Sirs, I try to import budget header and budget line by using DTW, however error message found, "Cannot find this object in B1 application defined, object defined error 65171. Regards, Saw Hua

Hi Javier,
Please check below links.
DTW Error 65171
DTW error 65171
DTW, Unkonwn error 1005!65171
DTW error 65171 - Cannot find this object
DTW error65171
SAP B1 Data Transfer WorkBench : Data too large... | SCN
Hope this help
Regards::::
Atul Chakraborty

Work Manager both Global Work Managers & Application-scoped Work Managers

Hi all,
I want to use both Global Work Managers & Application-scoped Work Managers in my domain [single], is it possible?
Basically I want to make sure my domain have fix number of thread.
In my environment, I have multiple domains on a single machine, so I want to make sure every domain has fix number of threads to maintain the whole system integrity.
if I won't make sure this, there could be scenario that one particular domain is taking much of the CPU usages than others.
Thanks,
Qumar

Hello Fred,
Thank you very much for reply.
I totally agree with you but in my scenario, I have multiple domains on a single box.
and I am afraid that there could be a situation where one bad application of a particular domain may take most of the CPU usages.
What I can do is: I can define max thread constrain to all the applications of all the domains but it is not acceptable bcz we have hundreds of applications per domain.
So what I want is: to define some kind of thread constrain at the domain level [so that I can have CPU usages allocated to every domain] as well as some kind of thread constrain to few applications [non prioritize].
I tried this by defining Global Work Managers & Application-scoped Work Managers but I found that applications only respect to Application-scoped Work Managers.
or if I have some kind of way that make sure certain percentage of CPU usages is allocated to a particular domain?
hope I have made my self clear.
Thanks,
Qumar

APPLICATION SCOPED DATASOURCE

Is possible to set the "Emulate two phase commit for non XA Driver" property for
an application scoped datasource??
Thanx

Is possible to set the "Emulate two phase commit for non XA Driver" property for
an application scoped datasource??
Thanx

BI Application Callable Object

Hi,
I am new to Guided Procedures.
I tried to use BI Application Callable Object under Services Type and i created a BI System in Portal to use in the callable object.when i use it in the callable object it is showing error cannot connect to system .
Can you help me how to create a system in Portal and help me with a scenario how to use BI Application Callable Object.
Regards,
Bala Baskaran.S

Hi KC,
When you start your process from GP Runtime, does the actual action/callable object open in a new window?
Have a look at this SAP Note:
[Error when executing a GP task - Page builder|https://www.sdn.sap.com/irj/servlet/prt/portal/prtroot/com.sap.km.cm.docs/oss_notes/sdn_oss_bc_gp/~form/handler%7b5f4150503d3030323030363832353030303030303031393732265f4556454e543d444953504c4159265f4e4e554d3d393831353137%7d]
Although the error message you are getting is different, but if your callable object opens in a new window, then the problem (in most probability) is the same as mentioned in the SAP Note.
Also, try testing the Web Dynpro callable object in standalone mode. For more information on this, see:
[Testing Callable Objects|http://help.sap.com/saphelp_nw04s/helpdata/en/4c/588041a17e060de10000000a1550b0/frameset.htm]
Bye
Ankur

Application scope objects(opinions wanted)

Hi All
Looking for educated opinions on the pros/cons of application scope objects. I am thinking about creating a read-only application scope hashmap representation of some static data in my database. When queried at the database level it can cause relatively long delays (3-4 seconds) and sometimes must be stored in many sessions on the server. I am thinking just one read-only object stored at app scope will cut down on the waste of memory, as well as skyrocket the speed of retrieving this data.
Please give me your opinions!!! I can tell you a little more about the app if you need more info to make an educated statement...
Thanks
Greg B

You can use the Properties Object for static data that can be persisted on a filesystem. Also, I assume that you can hold quite a bit of data too. A file read should be faster than a database query. Also if you do the connect once and save the connection for several reads, that works too. The only real slow operation, outside of large resultsets, would be the initial connect.
I always design up two or three possible solutions and sometimes I protpotype each one. Sometimes one of the tests will prove to be the exact opposite choice of the one you thought would work.
Now that I have written your response, I think that you could create a custom class to hold data, but would that not just be a copy of the properties object. If it's key/value you need, that's the choice.
Stand back and ask, "What is the data type of the high level objects?"
Also, SUN has good articles on almost everything in the JDK.
David Whitehurst
[email protected]

Application implicit object - undefined Variable!!??

          Hi!
          Is anybody able to access
          the "application" implicit object and
          the "pageContext" implicit object from
          a jspInit() method when an application is deployed as a War file?
          Thanks.


what is an application implicit Object ?

Web Dynpro application callable object error: Page Builder Not available

Hi, SDN Fellow.
I created a callable object of Web Dynpro application. The callable object is atatched to an Action, and Action --> Block, and Block --> Process.
I initiate the process in GP Runtime, when it comes to the Action screen the Web Dynpro application atatched to, I got the following error:
The page builder required to display this application UI inside the portal environment is not available.
As aa comparison, another callable object that atatched to a Web Dynpro component (that implement GP interface) is working fine.
Please advise.
Thanks in advance,
KC

Hi KC,
When you start your process from GP Runtime, does the actual action/callable object open in a new window?
Have a look at this SAP Note:
[Error when executing a GP task - Page builder|https://www.sdn.sap.com/irj/servlet/prt/portal/prtroot/com.sap.km.cm.docs/oss_notes/sdn_oss_bc_gp/~form/handler%7b5f4150503d3030323030363832353030303030303031393732265f4556454e543d444953504c4159265f4e4e554d3d393831353137%7d]
Although the error message you are getting is different, but if your callable object opens in a new window, then the problem (in most probability) is the same as mentioned in the SAP Note.
Also, try testing the Web Dynpro callable object in standalone mode. For more information on this, see:
[Testing Callable Objects|http://help.sap.com/saphelp_nw04s/helpdata/en/4c/588041a17e060de10000000a1550b0/frameset.htm]
Bye
Ankur

Deploying Java Web Application (WAR-File) into a cluster environment

Hi,
we have a web application which has to read from and write to the file system.
Since a short time we have a cluster environment (2 parallel servers) and since thisa time we have the problem, that files are worked double in the cluster. The application is working on both servers now and so we have this problem.
Does anybody know how we have to deploy the application correctly in a cluster environment or do we have to change anything in our source code of the application?
I didn't find any documentation about this.
At the moment we have deployed the application on one of the two servers only, but I think there must be a better way to solve this problem.
Thanks for your replies.
Regards
Thorsten

Hi,
I think first you need to wrap it into an EAR file, then you can deploy it.
As far as I know standalone deployment of WAR is deprecated as of 640.
similar threads:
How to deploy .war on NWDI
Deploying an existing WAR file into the Portal
Hopefully this tutorial also gives some idea:
http://help.sap.com/saphelp_nw70ehp1/helpdata/en/70/13353094af154a91cbe982d7dd0118/frameset.htm
Regards,
Ervin

Help: PhaseListener -session or Application scoped?

Hi.,
I am using default PhaseListener in my backing bean's (for 2 beans) constructor with a method as shown below:
public void beforePhase(PhaseEvent event) {
resetValues();
}So whenever a page reloads then this method gets invoked. Its working pretty fine.
The problem is when I open a new browser and open the application's index page then resetValues() method got invoked.
I saw with debug that the PhaseListener array inside the lifecycle was having the old one's backing bean (PhaseListener).
I do I restrict the PhaseListener to session scope?
Any help is highly appreciated.

see the Javadocs of PhaseListener:
An interface implemented by objects that wish to be notified at the beginning and ending of processing for each standard phase of the request processing lifecycle.
http://java.sun.com/javaee/javaserverfaces/1.1/docs/api/javax/faces/event/PhaseListener.html

Application scoped objects in a cluster

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