Re: client-server Object Caching
Hi again, Amol Pophale wrote: ... So you use PB-api only for read-only operations and persist objects via the server - right? And on the server you don't use OJB? Can you describe a little more? YES U ARE ABSOLUTELY CORRECT I AM MOT USING OJB ON SERVER SIDE. ... I CANT FIRE QUERIES EVERYTIME ON DATABSE DIRECTLY BECAUSE I WANT TO USE CACHE TO IMPROVE PERFORMANCE BUT I WANT OT KNOW HOW CLIENT CAN KNOW THAT DATABSE OBJECT IS CHANGED SO IT CAN REMOVE THAT OBJECT FROM CACHE. I HAVE ONE SOLUTION, WHEN SERVER UPDATES DATABSE IT SHOULD TELL CLIENT THAT I HAVE UPDATED DATABSE SO CLIENT CAN REMOVE THAT OBJECT FROM CACHE. HOW DO U FINFD THIS SOLUTION? Sounds ok for me, if the number of clients is less and the frequency of updates is low (in other cases you need a very fast intranet and very performant server nodes ;-)). I don't know a better way. Be careful with ObjectCache implementations and referenced objects. Currently the implemetations are quite simple and cache the main object with all references. Remove only remove the main object, if the same object was part of a collection of another main object it will not be removed. I will start a new ObjectCacheImplementation in near future only holds Identity objects of referenced objects. Maybe you have to tweak one of the existing cache implementations. It is possible to refresh referened objects but this could lead in DB access. regards, Armin ONE MORE QUESTIONS DO U KNOW OTHER TOOL BETTER THAN THIS FOR OBJECT RELATIONAL MAPPING? I HAVE READ ABOUT TOPLINK FROM ORACLE, COCOBASE, HYBERNET BUT I DONT KNOW HOW ARE THEY? AND WHAT IS DIFF BETWEEN THEM? IF U HAVE ANY INFO PLZ LET ME KNOW regards, Armin This is my problem Thanks & Regards Amol Pophale. Yahoo! Messenger - Communicate instantly..."Ping" your friends today! Download Messenger Now http://uk.messenger.yahoo.com/download/index.html - 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] Yahoo! Messenger - Communicate instantly..."Ping" your friends today! Download Messenger Now http://uk.messenger.yahoo.com/download/index.html - 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: client-server Object Caching
I think the only way for the client to be aware of server-side modifications to the database is to use a distributed cache (OSCache, Swarmcache, jcs, ...). The other way is, as Armin mentionned, not to use cache at all on the client. For other tools to do o/r mapping see http://c2.com/cgi-bin/wiki?ObjectRelationalToolComparison Guillaume -Message d'origine- De : Amol Pophale [mailto:[EMAIL PROTECTED] Envoyé : mardi 4 mai 2004 12:14 À : OJB Users List Objet : Re: client-server Object Caching Hi Armin, Thanks anyway for the reply read inline comments with block letters. Regards, Amol --- Armin Waibel <[EMAIL PROTECTED]> wrote: > Hi Amol, > > I read your previous posts carefully too, but I'm > not sure that I can help. > > Amol Pophale wrote: > > Hi All, > > Please read carefully and suggest me solution. > > I am working with one MNC s/w company.My > application > > is web-based client-server application in which > client > > and server are on different machines and uses same > > database. One imp thing one client might connect > to > > more than one servers.Each server has one database > > which may be on server itself or on third machine. > > These servers stores some data in database. > > and also send a xml copy of same data on some port > > to client.web Clint get this data from server in > the > > form of xml parses this xml and creates objects > from > > that and stores in memory. If there are any > changes in > > data server notify client so client can update its > > in-memory store.[client is not using database > > directly (jdbc)because firing query on Database > every > > time is not feasible with current DB schema]But > > disadvantage of this is, if clients connect to > > multiple server [yes, there may be more than one > > servers]then performance of web-server on client > > decrease because it store data of all server in > > memory. > > Now we redesign the database schema and now client > > can connect to each server's database directly > using > > OJB PersistanceBroker API and get data. > > So you use PB-api only for read-only operations and > persist objects via > the server - right? > And on the server you don't use OJB? > Can you describe a little more? YES U ARE ABSOLUTELY CORRECT I AM MOT USING OJB ON SERVER SIDE. > > > IN Object > > cache implementation if there is some data in > cache > > and > > same data get changed by server how clients knows > this > > change and cache can be updated? > > hmm, I don't recommend to use a distributed cache on > client side this > will be overkill if you run more than a few clients. > If you allow direct > access from the client to the DB I assume > client/server/DB run in an > intranet. Do the client have to recognize changes in > DB immediately or > is latency allowed? If not I recommend not cache > data on client side or > to use the per broker cache (cache only data within > a transaction or > till the PB instance was closed), otherwise you can > use cached object > 'timeout' property of the default object cache. I CANT FIRE QUERIES EVERYTIME ON DATABSE DIRECTLY BECAUSE I WANT TO USE CACHE TO IMPROVE PERFORMANCE BUT I WANT OT KNOW HOW CLIENT CAN KNOW THAT DATABSE OBJECT IS CHANGED SO IT CAN REMOVE THAT OBJECT FROM CACHE. I HAVE ONE SOLUTION, WHEN SERVER UPDATES DATABSE IT SHOULD TELL CLIENT THAT I HAVE UPDATED DATABSE SO CLIENT CAN REMOVE THAT OBJECT FROM CACHE. HOW DO U FINFD THIS SOLUTION? ONE MORE QUESTIONS DO U KNOW OTHER TOOL BETTER THAN THIS FOR OBJECT RELATIONAL MAPPING? I HAVE READ ABOUT TOPLINK FROM ORACLE, COCOBASE, HYBERNET BUT I DONT KNOW HOW ARE THEY? AND WHAT IS DIFF BETWEEN THEM? IF U HAVE ANY INFO PLZ LET ME KNOW > > regards, > Armin > > > This is my problem > > > > Thanks & Regards > > Amol Pophale. > > > > > > > > > > > > > > > > > > > > > Yahoo! Messenger - Communicate instantly..."Ping" > > your friends today! Download Messenger Now > > http://uk.messenger.yahoo.com/download/index.html > > > > > - > > 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] > Yahoo! Messenger - Communicate instantly..."Ping" your friends today! Download Messenger Now http://uk.messenger.yahoo.com/download/index.html - 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: client-server Object Caching
Hi Armin, Thanks anyway for the reply read inline comments with block letters. Regards, Amol --- Armin Waibel <[EMAIL PROTECTED]> wrote: > Hi Amol, > > I read your previous posts carefully too, but I'm > not sure that I can help. > > Amol Pophale wrote: > > Hi All, > > Please read carefully and suggest me solution. > > I am working with one MNC s/w company.My > application > > is web-based client-server application in which > client > > and server are on different machines and uses same > > database. One imp thing one client might connect > to > > more than one servers.Each server has one database > > which may be on server itself or on third machine. > > These servers stores some data in database. > > and also send a xml copy of same data on some port > > to client.web Clint get this data from server in > the > > form of xml parses this xml and creates objects > from > > that and stores in memory. If there are any > changes in > > data server notify client so client can update its > > in-memory store.[client is not using database > > directly (jdbc)because firing query on Database > every > > time is not feasible with current DB schema]But > > disadvantage of this is, if clients connect to > > multiple server [yes, there may be more than one > > servers]then performance of web-server on client > > decrease because it store data of all server in > > memory. > > Now we redesign the database schema and now client > > can connect to each server's database directly > using > > OJB PersistanceBroker API and get data. > > So you use PB-api only for read-only operations and > persist objects via > the server - right? > And on the server you don't use OJB? > Can you describe a little more? YES U ARE ABSOLUTELY CORRECT I AM MOT USING OJB ON SERVER SIDE. > > > IN Object > > cache implementation if there is some data in > cache > > and > > same data get changed by server how clients knows > this > > change and cache can be updated? > > hmm, I don't recommend to use a distributed cache on > client side this > will be overkill if you run more than a few clients. > If you allow direct > access from the client to the DB I assume > client/server/DB run in an > intranet. Do the client have to recognize changes in > DB immediately or > is latency allowed? If not I recommend not cache > data on client side or > to use the per broker cache (cache only data within > a transaction or > till the PB instance was closed), otherwise you can > use cached object > 'timeout' property of the default object cache. I CANT FIRE QUERIES EVERYTIME ON DATABSE DIRECTLY BECAUSE I WANT TO USE CACHE TO IMPROVE PERFORMANCE BUT I WANT OT KNOW HOW CLIENT CAN KNOW THAT DATABSE OBJECT IS CHANGED SO IT CAN REMOVE THAT OBJECT FROM CACHE. I HAVE ONE SOLUTION, WHEN SERVER UPDATES DATABSE IT SHOULD TELL CLIENT THAT I HAVE UPDATED DATABSE SO CLIENT CAN REMOVE THAT OBJECT FROM CACHE. HOW DO U FINFD THIS SOLUTION? ONE MORE QUESTIONS DO U KNOW OTHER TOOL BETTER THAN THIS FOR OBJECT RELATIONAL MAPPING? I HAVE READ ABOUT TOPLINK FROM ORACLE, COCOBASE, HYBERNET BUT I DONT KNOW HOW ARE THEY? AND WHAT IS DIFF BETWEEN THEM? IF U HAVE ANY INFO PLZ LET ME KNOW > > regards, > Armin > > > This is my problem > > > > Thanks & Regards > > Amol Pophale. > > > > > > > > > > > > > > > > > > > > > Yahoo! Messenger - Communicate instantly..."Ping" > > your friends today! Download Messenger Now > > http://uk.messenger.yahoo.com/download/index.html > > > > > - > > 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] > Yahoo! Messenger - Communicate instantly..."Ping" your friends today! Download Messenger Now http://uk.messenger.yahoo.com/download/index.html - To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
Re: client-server Object Caching
Hi Amol, I read your previous posts carefully too, but I'm not sure that I can help. Amol Pophale wrote: Hi All, Please read carefully and suggest me solution. I am working with one MNC s/w company.My application is web-based client-server application in which client and server are on different machines and uses same database. One imp thing one client might connect to more than one servers.Each server has one database which may be on server itself or on third machine. These servers stores some data in database. and also send a xml copy of same data on some port to client.web Clint get this data from server in the form of xml parses this xml and creates objects from that and stores in memory. If there are any changes in data server notify client so client can update its in-memory store.[client is not using database directly (jdbc)because firing query on Database every time is not feasible with current DB schema]But disadvantage of this is, if clients connect to multiple server [yes, there may be more than one servers]then performance of web-server on client decrease because it store data of all server in memory. Now we redesign the database schema and now client can connect to each server's database directly using OJB PersistanceBroker API and get data. So you use PB-api only for read-only operations and persist objects via the server - right? And on the server you don't use OJB? Can you describe a little more? IN Object cache implementation if there is some data in cache and same data get changed by server how clients knows this change and cache can be updated? hmm, I don't recommend to use a distributed cache on client side this will be overkill if you run more than a few clients. If you allow direct access from the client to the DB I assume client/server/DB run in an intranet. Do the client have to recognize changes in DB immediately or is latency allowed? If not I recommend not cache data on client side or to use the per broker cache (cache only data within a transaction or till the PB instance was closed), otherwise you can use cached object 'timeout' property of the default object cache. regards, Armin This is my problem Thanks & Regards Amol Pophale. Yahoo! Messenger - Communicate instantly..."Ping" your friends today! Download Messenger Now http://uk.messenger.yahoo.com/download/index.html - 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: client/server Object Caching [Very Urgent]
Amol, I think you face and underlying problem related to the architecture of your application. I do not know if you are familiar with the MVC pattern, but it seems considering applying it to your project might be of help. The basic idea is to let the Controller in the server "talk" to the Model (your business objects) and to the View (your client app, where you might have another MVC pattern in place to handle the client stuff). In your client you should handle (present to the user or send to the server) just values (or ValueObjects if you prefer but no "business objects" or direct access to the database). I´m trying to say the client app should not know anything about OJB, it´s just the server app the only one that actually talks to the DB using OJB framework in this case. Once the controller receive from the client some data and some commands or actions, it should dispatch an "action", letting your "actions", take care of situation like the one you are presenting (dirty objects). We´ve done several developments applying this pattern to Swing based clients app in client/server scenarios with very good results (we ´ve implemented in swing based solutions tons of good ideas "borrowed" from Apache Struts among other implementations of the MVC pattern). Regards, Gustavo. Amol Pophale <[EMAIL PROTECTED]> wrote on 29/04/2004 06:30:58 a.m.: > Hi All, > I just learned OJB. > I have written one application in OJB. > My application is client-server application in which > client and server are on different machines and using > same databse which may be on third machine. > Right now i have one query. > server stores some java object in databse using > PersistaceBroker APIs. Client retrives these object > on its machine using same i.e. OJB > Now if any object is updated by server which is in > client object cache How can we update client object > cache when server updates the object in database. > Because I think server cache and client cache are > different. > I need this very urgent. > > Thanks in advance > Amol Pophale. > > > > > > > > Yahoo! Messenger - Communicate instantly..."Ping" > your friends today! Download Messenger Now > http://uk.messenger.yahoo.com/download/index.html > > - > 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: client/server Object Caching [Very Urgent]
You are effectively operating in a cluster, where your workstations are also cluster nodes: http://db.apache.org/ojb/howto-work-with-clustering.html -Brian On Apr 29, 2004, at 7:53 AM, Amol Pophale wrote: Hi Brain Thanks a lot for urgent reply. You said I need to use one of the distributed caches (JCS, OSCache, or Coherence) can u please tell where i can get details info about this or if u know can u tell me by some example or where can i get that API help etc. I mean more detail. Note:do u anything about PersistanceBrokerClient class? Thanks Amol --- Brian McCallister <[EMAIL PROTECTED]> wrote: > You need to use one of the distributed caches (JCS, OSCache, or Coherence). The other option, which tends to be the easiest, is to use a per-broker cache (non-distributed) and optimistic transactions, in which case you acknowledge that data in cache for the lifetime of one broker (usually short depending on how you use it) may be dirty if ti is in contention. This doesn't work for highly contentious data, however. -Brian On Apr 29, 2004, at 5:30 AM, Amol Pophale wrote: Hi All, I just learned OJB. I have written one application in OJB. My application is client-server application in which client and server are on different machines and using same databse which may be on third machine. Right now i have one query. server stores some java object in databse using PersistaceBroker APIs. Client retrives these object on its machine using same i.e. OJB Now if any object is updated by server which is in client object cache How can we update client object cache when server updates the object in database. Because I think server cache and client cache are different. I need this very urgent. Thanks in advance Amol Pophale. Yahoo! Messenger - Communicate instantly..."Ping" your friends today! Download Messenger Now http://uk.messenger.yahoo.com/download/index.html - 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] Yahoo! Messenger - Communicate instantly..."Ping" your friends today! Download Messenger Now http://uk.messenger.yahoo.com/download/index.html - 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: client/server Object Caching [Very Urgent]
Hi Brain Thanks a lot for urgent reply. You said I need to use one of the distributed caches (JCS, OSCache, or Coherence) can u please tell where i can get details info about this or if u know can u tell me by some example or where can i get that API help etc. I mean more detail. Note:do u anything about PersistanceBrokerClient class? Thanks Amol --- Brian McCallister <[EMAIL PROTECTED]> wrote: > You need to use one of the distributed caches (JCS, > OSCache, or > Coherence). > > The other option, which tends to be the easiest, is > to use a per-broker > cache (non-distributed) and optimistic transactions, > in which case you > acknowledge that data in cache for the lifetime of > one broker (usually > short depending on how you use it) may be dirty if > ti is in contention. > This doesn't work for highly contentious data, > however. > > -Brian > > On Apr 29, 2004, at 5:30 AM, Amol Pophale wrote: > > > Hi All, > > I just learned OJB. > > I have written one application in OJB. > > My application is client-server application in > which > > client and server are on different machines and > using > > same databse which may be on third machine. > > Right now i have one query. > > server stores some java object in databse using > > PersistaceBroker APIs. Client retrives these > object > > on its machine using same i.e. OJB > > Now if any object is updated by server which is in > > client object cache How can we update client > object > > cache when server updates the object in database. > > Because I think server cache and client cache are > > different. > > I need this very urgent. > > > > Thanks in advance > > Amol Pophale. > > > > > > > > > > > > > > > > > Yahoo! Messenger - Communicate instantly..."Ping" > > your friends today! Download Messenger Now > > http://uk.messenger.yahoo.com/download/index.html > > > > > - > > 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] > Yahoo! Messenger - Communicate instantly..."Ping" your friends today! Download Messenger Now http://uk.messenger.yahoo.com/download/index.html - To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
Re: client/server Object Caching [Very Urgent]
You need to use one of the distributed caches (JCS, OSCache, or Coherence). The other option, which tends to be the easiest, is to use a per-broker cache (non-distributed) and optimistic transactions, in which case you acknowledge that data in cache for the lifetime of one broker (usually short depending on how you use it) may be dirty if ti is in contention. This doesn't work for highly contentious data, however. -Brian On Apr 29, 2004, at 5:30 AM, Amol Pophale wrote: Hi All, I just learned OJB. I have written one application in OJB. My application is client-server application in which client and server are on different machines and using same databse which may be on third machine. Right now i have one query. server stores some java object in databse using PersistaceBroker APIs. Client retrives these object on its machine using same i.e. OJB Now if any object is updated by server which is in client object cache How can we update client object cache when server updates the object in database. Because I think server cache and client cache are different. I need this very urgent. Thanks in advance Amol Pophale. Yahoo! Messenger - Communicate instantly..."Ping" your friends today! Download Messenger Now http://uk.messenger.yahoo.com/download/index.html - 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]
