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Re: Input needed, using lazy load with business entities
Dotnet Distributed Applications microsoft.public.dotnet.distributed_apps
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Re: Input needed, using lazy load with business entities -
06-25-2003
, 06:52 AM
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Hi TEK, I'm having the same problem and the solution I'm thinking about to use is to hand the entity a logic instance (with your words). So the entity will call the logic component instance (via an interface) when it needs data to be lazy loaded. When strictly using Service Layer pattern [Fowler PoEAA], it seems to me that it creates this lazy load-problem... The solution I mention above doesn't feel that very good. I will carefully follow this thread to see if there will come up better proposals. Best Regards, Jimmy www.jnsk.se/weblog/ ### "TEK" <trondeirikkolloen (AT) hotmail (DOT) com> wrote in message news:eU7Qs9uODHA.1072 (AT) TK2MSFTNGP10 (DOT) phx.gbl... Hello I could need some input on this issue. All ideas would us received with thanks... Application structure: - Thin client (currently an windows app) - Business layer Business Entity components Business logic components - Data layer The Business Entity components is created by the Business logic components. typically usage: User user = new User(); UserInfo myself = user.GetUserByName("tek"); // do stuff with myself ;-) user.SaveUser(myself); The Business Entities may also contain other business entities, UserInfo may for example hold an collection of GroupInfo objects. (the groups a user is member of). So to the issue, with large listings (for example when calling user.GetAllUsers()), you may only need/want the basic information, not the connected info objects. Normally, a logical way to solve this would be to implement layze loading, meaning that the users Group would not be filled until the calling method actually called: GroupInfoCollection groups = myself.Groups(); But to do that, the entity layer would have to have a reference to the Business logic components, and wholia, a sircular reference. At the same time that would lead to put business logic into the info objects, which I'm not to keen on. Any good ideas out there? Best reagards, TEK |
#2
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Dear All, to solve this problem let the business entities to communicate with the Business Logic through an interface defined in the Business Entity package, but implemented in the Business Logic Data. Each BL class have to implement this interface. Such a kind of interface can be set by the BL at BE creation time Hope it helps, Fabrizio. Remember that lazy load is not the best way to go on in case your application is distributed. If infact the BLs are remote components the best way is to go to the opposite solution, (load as much as possible on each remote rountrip) "Jimmy Nilsson" <Jimmy.Nilsson (AT) nospam_jnsk (DOT) se> wrote in message news:eE5TNRvODHA.2316 (AT) TK2MSFTNGP11 (DOT) phx.gbl... Hi TEK, I'm having the same problem and the solution I'm thinking about to use is to hand the entity a logic instance (with your words). So the entity will call the logic component instance (via an interface) when it needs data to be lazy loaded. When strictly using Service Layer pattern [Fowler PoEAA], it seems to me that it creates this lazy load-problem... The solution I mention above doesn't feel that very good. I will carefully follow this thread to see if there will come up better proposals. Best Regards, Jimmy www.jnsk.se/weblog/ ### "TEK" <trondeirikkolloen (AT) hotmail (DOT) com> wrote in message news:eU7Qs9uODHA.1072 (AT) TK2MSFTNGP10 (DOT) phx.gbl... Hello I could need some input on this issue. All ideas would us received with thanks... Application structure: - Thin client (currently an windows app) - Business layer Business Entity components Business logic components - Data layer The Business Entity components is created by the Business logic components. typically usage: User user = new User(); UserInfo myself = user.GetUserByName("tek"); // do stuff with myself ;-) user.SaveUser(myself); The Business Entities may also contain other business entities, UserInfo may for example hold an collection of GroupInfo objects. (the groups a user is member of). So to the issue, with large listings (for example when calling user.GetAllUsers()), you may only need/want the basic information, not the connected info objects. Normally, a logical way to solve this would be to implement layze loading, meaning that the users Group would not be filled until the calling method actually called: GroupInfoCollection groups = myself.Groups(); But to do that, the entity layer would have to have a reference to the Business logic components, and wholia, a sircular reference. At the same time that would lead to put business logic into the info objects, which I'm not to keen on. Any good ideas out there? Best reagards, TEK |
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