c# - Another application architecture question -

i trying ddd , try describe in simple manner have done.

core project
core project contains entities, vo , domain services. example have user entity , userrelation entity. think know user entity. userrelation contains information how users connected each other follow , connect(bidirectional follow). because of have userdomainservice stateless methods follow(user,user) , connect(user, user).

public class user {     public string name { get; set; }     public string username { get; set; }      public void changeusername(stirng newusername)     {         applyevent(new userusernamechanged(newusername));     } }  public class userrelation {     ctor(user1, user2, isbidirectional)     public user user1 { get; set; }     public user user2 { get; set; }     public bool isbidirectional { get; set; } }  public class userdomainservice {     public userrelation follow(user user1, user user2)     {          return new userrelation(user1,user2,false);     } } 

repository project

i using nhibernate decided not create such project. instead using nhibernate directly. example, in ui user object db, change , call session.save(user).

the problem

if want operation follow this:

• get info db
• call follow(user1, user2) service
• save userrelation object db in end application code becomes bit complex. imagine if want use code in 2-3 places , @ point have refactor it.

my solution
solution create applicationservice project dirty work , force consumer use applicationservice instead of using entitties , domain services directly

public class userapplicationservice {     ctor(userdomainservice userdomainservice){}      user getuser(guid id)     {         return nhibernatesession.get(id)     }      public void follow(guid user1id, guid user2id)     {         var u1 = getuser(user1id);         var u2 = getuser(user2id);         var userrelation = _userdomainservice.follow(u1,u2);         nhibernatesession.save(userrelation);     }      public void changeusername(guid user, string newusername)     {         user.changeusername(newusername);         nhibernatesession.save(user);     } } 

is application service or bad? can see new service act repository can create userrepository class lets skip now. bothers me parameters in 2 methods. accept guids , service retrieves users db. other option pass directly user object. changeusername method 1 user entity + persistence.

well, think this?

i don't see wrong, in fact how company work has done it, long abstract out data access service part of business layer mediator between data layer , ui layer, saves repeating , making sure rules outlined operation fires.