c# - N-tier Application Data Model -

i develop ntier mvc application .net. have 4 layer. ui layer, servicelayer, business layer , dal. (i use ef5 dal)

i add project entities. projects structure this.

myproject.dal myproject.interfaces myproject.entities myproject.mvcwebui myproject.bll 

i wonder that, need type class model method's return. it's not neccessary store in database. shortly it's not entity.

for example have product entity. need model it's store product's status , count. how should locate it?

public enum prodreviewresult {     accepted = 1,     declined = 2,     banned = 4 }  //myproject.dal //i need here return typed model public list<object> getprodreviewstatusbyprodgroup(int userid, int prodgroupid) {     var query = p in _db.products         join pg in _db.prodgroups on p.prodgroupid equals pg.prodgroupid         pg.userid == userid && p.userid == userid         group p p         g         select new {prodviewresult = g.key, prodcount = g.count()};      var reviewstatus = new list<object>();     foreach (var result in query)     {         reviewstatus.add(new {result.prodviewresult, result.prodcount});     }      return reviewstatus; }  //this class model products group prodreviewstatus. //how should locate in project.  public prodreviewcount() {     public prodreviewstatus prodreviewstatus{get;set;}     public int count{get;set;} } 

i don't have intimate knowledge of application, seems excessive me. service layer, business layer , dal pretty same thing. they're part of domain. unless have reason not discussed here why need 3 distinct projects, i'd should trying merge of appropriate.

that said, you're talking dto (data transfer object). such, based on current structure, i'd should go dal project.