RE: Synchronization in cluster
With this usage scenario i would recommend sticky sessions. -Original Message- From: Igor [mailto:[EMAIL PROTECTED] Sent: Thursday, September 30, 2004 8:59 PM To: [EMAIL PROTECTED] Subject: Re: Synchronization in cluster Users of my application can upload comma separeted files, that are imported in database. This process can take 10-30 minutes, if file is large, so new Thread is started with import process and user is redirected to refreshing page, that displays status of import. Information about import process is stored in static variable (import thread and status jsp can access this information). If it happens in one JVM, everething is ok. But what will be in the case of load balancing? Thank you, Igor - To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
RE: Synchronization in cluster
That doesn't solve the problem -Original Message- From: Ralph Einfeldt [mailto:[EMAIL PROTECTED] Sent: Friday, October 01, 2004 4:26 AM To: Tomcat Users List Subject: RE: Synchronization in cluster With this usage scenario i would recommend sticky sessions. -Original Message- From: Igor [mailto:[EMAIL PROTECTED] Sent: Thursday, September 30, 2004 8:59 PM To: [EMAIL PROTECTED] Subject: Re: Synchronization in cluster Users of my application can upload comma separeted files, that are imported in database. This process can take 10-30 minutes, if file is large, so new Thread is started with import process and user is redirected to refreshing page, that displays status of import. Information about import process is stored in static variable (import thread and status jsp can access this information). If it happens in one JVM, everething is ok. But what will be in the case of load balancing? Thank you, Igor - To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED] --- Incoming mail is certified Virus Free. Checked by AVG anti-virus system (http://www.grisoft.com). Version: 6.0.768 / Virus Database: 515 - Release Date: 9/22/2004 --- Outgoing mail is certified Virus Free. Checked by AVG anti-virus system (http://www.grisoft.com). Version: 6.0.768 / Virus Database: 515 - Release Date: 9/22/2004 - To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
RE: Synchronization in cluster
Why not ? As I understood the static variable holds the information for the current upload. If the session is sticky the user will stay in the same jvm and see the same static variable with each refresh. I just see some downsides: - if you want to assure that the downloads are serialised you have to implement a locking mechanism. - you loose the central point to see all states at the same time. - if the instance that performs the update dies, the user will get to an instance that doesn't know anything about the download. -Original Message- From: Filip Hanik (lists) [mailto:[EMAIL PROTECTED] Sent: Friday, October 01, 2004 1:51 PM To: Tomcat Users List Subject: RE: Synchronization in cluster That doesn't solve the problem -Original Message- From: Ralph Einfeldt [mailto:[EMAIL PROTECTED] Sent: Friday, October 01, 2004 4:26 AM To: Tomcat Users List Subject: RE: Synchronization in cluster With this usage scenario i would recommend sticky sessions. - To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
Re: Synchronization in cluster
cause if you have two servers, two different sessions can perform upload in two different VMs. He never said there is only one session doing upload, he was asking for a distributed lock Filip - Original Message - From: Ralph Einfeldt [EMAIL PROTECTED] To: Tomcat Users List [EMAIL PROTECTED] Sent: Friday, October 01, 2004 7:36 AM Subject: RE: Synchronization in cluster Why not ? As I understood the static variable holds the information for the current upload. If the session is sticky the user will stay in the same jvm and see the same static variable with each refresh. I just see some downsides: - if you want to assure that the downloads are serialised you have to implement a locking mechanism. - you loose the central point to see all states at the same time. - if the instance that performs the update dies, the user will get to an instance that doesn't know anything about the download. -Original Message- From: Filip Hanik (lists) [mailto:[EMAIL PROTECTED] Sent: Friday, October 01, 2004 1:51 PM To: Tomcat Users List Subject: RE: Synchronization in cluster That doesn't solve the problem -Original Message- From: Ralph Einfeldt [mailto:[EMAIL PROTECTED] Sent: Friday, October 01, 2004 4:26 AM To: Tomcat Users List Subject: RE: Synchronization in cluster With this usage scenario i would recommend sticky sessions. - To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED] - To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
Re: Synchronization in cluster
You are right :-( Igor - Original Message - From: Filip Hanik - Dev [EMAIL PROTECTED] To: Tomcat Users List [EMAIL PROTECTED] Sent: Friday, October 01, 2004 5:31 PM Subject: Re: Synchronization in cluster cause if you have two servers, two different sessions can perform upload in two different VMs. He never said there is only one session doing upload, he was asking for a distributed lock Filip - Original Message - From: Ralph Einfeldt [EMAIL PROTECTED] To: Tomcat Users List [EMAIL PROTECTED] Sent: Friday, October 01, 2004 7:36 AM Subject: RE: Synchronization in cluster Why not ? As I understood the static variable holds the information for the current upload. If the session is sticky the user will stay in the same jvm and see the same static variable with each refresh. I just see some downsides: - if you want to assure that the downloads are serialised you have to implement a locking mechanism. - you loose the central point to see all states at the same time. - if the instance that performs the update dies, the user will get to an instance that doesn't know anything about the download. -Original Message- From: Filip Hanik (lists) [mailto:[EMAIL PROTECTED] Sent: Friday, October 01, 2004 1:51 PM To: Tomcat Users List Subject: RE: Synchronization in cluster That doesn't solve the problem -Original Message- From: Ralph Einfeldt [mailto:[EMAIL PROTECTED] Sent: Friday, October 01, 2004 4:26 AM To: Tomcat Users List Subject: RE: Synchronization in cluster With this usage scenario i would recommend sticky sessions. - To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED] - To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
RE : Synchronization in cluster
Hi, What are your needs? Why distributed singleton or distributed locking are so important ? Perhaps you can use Database to implement locking functionality and Jgroups library to replicate state (or distributed singleton) across members of a group (see www.jgroups.org). -Message d'origine- De : Igor [mailto:[EMAIL PROTECTED] Envoyé : mercredi 29 septembre 2004 20:42 À : [EMAIL PROTECTED] Objet : Re: Synchronization in cluster Hello! if you are talking about distributed locking, then the answer is no Thank you for reply ! Our web application uses locking and Singleton pattern. I am making researches - is there a possibility to move to cluster architecture or load balancing. Distributed locking is not possible. Distiributed Singleton (static variables) seems not to be possible too. So web applications, that use locking or Singleton cannot use cluster architecture or load balancing. Maybe there is indirect way of implementing distributed locking or distributed Singleton? For example, code that needs synchronization may be concentrated in main Tomcat, and other Tomcats will call this code via http or SOAP? Is there any way to move web application with locking and Singleton to cluster or load balancing? Thank you, Igor - To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED] - To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
Re: RE : Synchronization in cluster
distributed locking of session data implies you need something like a distributed cache. If that is the case, maybe you should look at Coherence. distributed locking is meant to solve a specific problem, so unless you really need to synchronize distributed objects like a distributed cache, I would avoid using it. some people tackle type of problem with JMS. unless you plan to extend TC5 session replication with these features it's going to be a while. peter On Thu, 30 Sep 2004 09:41:41 +0200, LERBSCHER Jean-Pierre [EMAIL PROTECTED] wrote: Hi, What are your needs? Why distributed singleton or distributed locking are so important ? Perhaps you can use Database to implement locking functionality and Jgroups library to replicate state (or distributed singleton) across members of a group (see www.jgroups.org). - To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
Re: Synchronization in cluster
Hello! Thank you for answers! I will try to use JGroups We have data, that is often need to be read. And it is rarely written. It is implemented using Singleton pattern. Synchronization is used in several parts of web application. It is used mostly to access database Thank you, Igor - Original Message - From: LERBSCHER Jean-Pierre [EMAIL PROTECTED] To: 'Tomcat Users List' [EMAIL PROTECTED] Sent: Thursday, September 30, 2004 10:41 AM Subject: RE : Synchronization in cluster Hi, What are your needs? Why distributed singleton or distributed locking are so important ? Perhaps you can use Database to implement locking functionality and Jgroups library to replicate state (or distributed singleton) across members of a group (see www.jgroups.org).
Re: Synchronization in cluster
sounds like your system needs a little rethinking, if you have singleton access to your DB. That is why the DBs are transactional, so that you can use connection pooling. you can use JGroups, but you might run into serious performance problems, not because of JGroups, but because of the fact that you want to lock several tomcats in a distributed lock when accessing the DB. Filip - Original Message - From: Igor [EMAIL PROTECTED] To: [EMAIL PROTECTED] Sent: Thursday, September 30, 2004 10:16 AM Subject: Re: Synchronization in cluster Hello! Thank you for answers! I will try to use JGroups We have data, that is often need to be read. And it is rarely written. It is implemented using Singleton pattern. Synchronization is used in several parts of web application. It is used mostly to access database Thank you, Igor - Original Message - From: LERBSCHER Jean-Pierre [EMAIL PROTECTED] To: 'Tomcat Users List' [EMAIL PROTECTED] Sent: Thursday, September 30, 2004 10:41 AM Subject: RE : Synchronization in cluster Hi, What are your needs? Why distributed singleton or distributed locking are so important ? Perhaps you can use Database to implement locking functionality and Jgroups library to replicate state (or distributed singleton) across members of a group (see www.jgroups.org). - To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
Re: Synchronization in cluster
I would second Filip's comment. locking tomcat in this fashion is not advised, unless you have solid experience with it. It's not as easy as one would think. peter On Thu, 30 Sep 2004 10:36:34 -0500, Filip Hanik - Dev [EMAIL PROTECTED] wrote: sounds like your system needs a little rethinking, if you have singleton access to your DB. That is why the DBs are transactional, so that you can use connection pooling. you can use JGroups, but you might run into serious performance problems, not because of JGroups, but because of the fact that you want to lock several tomcats in a distributed lock when accessing the DB. Filip - Original Message - From: Igor [EMAIL PROTECTED] To: [EMAIL PROTECTED] Sent: Thursday, September 30, 2004 10:16 AM Subject: Re: Synchronization in cluster Hello! Thank you for answers! I will try to use JGroups We have data, that is often need to be read. And it is rarely written. It is implemented using Singleton pattern. Synchronization is used in several parts of web application. It is used mostly to access database Thank you, Igor - Original Message - From: LERBSCHER Jean-Pierre [EMAIL PROTECTED] To: 'Tomcat Users List' [EMAIL PROTECTED] Sent: Thursday, September 30, 2004 10:41 AM Subject: RE : Synchronization in cluster Hi, What are your needs? Why distributed singleton or distributed locking are so important ? Perhaps you can use Database to implement locking functionality and Jgroups library to replicate state (or distributed singleton) across members of a group (see www.jgroups.org). - To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED] - To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
Re: Synchronization in cluster
Hello! Thank you for advice ! I will think about restructure my application. Users of my application can upload comma separeted files, that are imported in database. This process can take 10-30 minutes, if file is large, so new Thread is started with import process and user is redirected to refreshing page, that displays status of import. Information about import process is stored in static variable (import thread and status jsp can access this information). If it happens in one JVM, everething is ok. But what will be in the case of load balancing? Thank you, Igor - Original Message - From: Filip Hanik - Dev [EMAIL PROTECTED] To: Tomcat Users List [EMAIL PROTECTED] Sent: Thursday, September 30, 2004 6:36 PM Subject: Re: Synchronization in cluster sounds like your system needs a little rethinking, if you have singleton access to your DB. That is why the DBs are transactional, so that you can use connection pooling. you can use JGroups, but you might run into serious performance problems, not because of JGroups, but because of the fact that you want to lock several tomcats in a distributed lock when accessing the DB. Filip - Original Message - From: Igor [EMAIL PROTECTED] To: [EMAIL PROTECTED] Sent: Thursday, September 30, 2004 10:16 AM Subject: Re: Synchronization in cluster Hello! Thank you for answers! I will try to use JGroups We have data, that is often need to be read. And it is rarely written. It is implemented using Singleton pattern. Synchronization is used in several parts of web application. It is used mostly to access database Thank you, Igor - Original Message - From: LERBSCHER Jean-Pierre [EMAIL PROTECTED] To: 'Tomcat Users List' [EMAIL PROTECTED] Sent: Thursday, September 30, 2004 10:41 AM Subject: RE : Synchronization in cluster Hi, What are your needs? Why distributed singleton or distributed locking are so important ? Perhaps you can use Database to implement locking functionality and Jgroups library to replicate state (or distributed singleton) across members of a group (see www.jgroups.org).
Re: Synchronization in cluster
If it happens in one JVM, everething is ok. But what will be in the case of load balancing? and that is why they pay you the big bucks...to figure this stuff out :) remember, sometimes the solution is super simple, just not thought of. Filip - Original Message - From: Igor [EMAIL PROTECTED] To: [EMAIL PROTECTED] Sent: Thursday, September 30, 2004 1:58 PM Subject: Re: Synchronization in cluster Hello! Thank you for advice ! I will think about restructure my application. Users of my application can upload comma separeted files, that are imported in database. This process can take 10-30 minutes, if file is large, so new Thread is started with import process and user is redirected to refreshing page, that displays status of import. Information about import process is stored in static variable (import thread and status jsp can access this information). If it happens in one JVM, everething is ok. But what will be in the case of load balancing? Thank you, Igor - Original Message - From: Filip Hanik - Dev [EMAIL PROTECTED] To: Tomcat Users List [EMAIL PROTECTED] Sent: Thursday, September 30, 2004 6:36 PM Subject: Re: Synchronization in cluster sounds like your system needs a little rethinking, if you have singleton access to your DB. That is why the DBs are transactional, so that you can use connection pooling. you can use JGroups, but you might run into serious performance problems, not because of JGroups, but because of the fact that you want to lock several tomcats in a distributed lock when accessing the DB. Filip - Original Message - From: Igor [EMAIL PROTECTED] To: [EMAIL PROTECTED] Sent: Thursday, September 30, 2004 10:16 AM Subject: Re: Synchronization in cluster Hello! Thank you for answers! I will try to use JGroups We have data, that is often need to be read. And it is rarely written. It is implemented using Singleton pattern. Synchronization is used in several parts of web application. It is used mostly to access database Thank you, Igor - Original Message - From: LERBSCHER Jean-Pierre [EMAIL PROTECTED] To: 'Tomcat Users List' [EMAIL PROTECTED] Sent: Thursday, September 30, 2004 10:41 AM Subject: RE : Synchronization in cluster Hi, What are your needs? Why distributed singleton or distributed locking are so important ? Perhaps you can use Database to implement locking functionality and Jgroups library to replicate state (or distributed singleton) across members of a group (see www.jgroups.org). - To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
Re: Synchronization in cluster
Thank you :-) Igor - Original Message - From: Filip Hanik - Dev [EMAIL PROTECTED] To: Tomcat Users List [EMAIL PROTECTED] Sent: Thursday, September 30, 2004 10:42 PM Subject: Re: Synchronization in cluster If it happens in one JVM, everething is ok. But what will be in the case of load balancing? and that is why they pay you the big bucks...to figure this stuff out :) remember, sometimes the solution is super simple, just not thought of. Filip - To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
Re: Synchronization in cluster
if you are talking about distributed locking, then the answer is no
Filip
- Original Message -
From: Igor [EMAIL PROTECTED]
To: [EMAIL PROTECTED]
Sent: Tuesday, September 28, 2004 11:43 PM
Subject: Synchronization in cluster
Hello!
We use synchronization on several JSP and classes:
synchronized ( ... ) {
...
}
But what about synchronization in cluster?
Tomcats in cluster will work in different JVM on different computers.
Is there a possibility of such synchronization in cluster?
Thank you,
Igor
-
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For additional commands, e-mail: [EMAIL PROTECTED]
Re: Synchronization in cluster
Hello! if you are talking about distributed locking, then the answer is no Thank you for reply ! Our web application uses locking and Singleton pattern. I am making researches - is there a possibility to move to cluster architecture or load balancing. Distributed locking is not possible. Distiributed Singleton (static variables) seems not to be possible too. So web applications, that use locking or Singleton cannot use cluster architecture or load balancing. Maybe there is indirect way of implementing distributed locking or distributed Singleton? For example, code that needs synchronization may be concentrated in main Tomcat, and other Tomcats will call this code via http or SOAP? Is there any way to move web application with locking and Singleton to cluster or load balancing? Thank you, Igor - To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
