Вроде все ошибки устранил. не запускал.

PARR.AIHIT/AIHIT/Syncher.cs

@@ -25,7 +25,7 @@ namespace PARR.AIHIT
         private readonly IApplicationTypeService appTypeService;
         private readonly IApplicationInHostService appInHostService;
 
-        public List<ApplicationType> AppTypes { get; private set; }
+        public List<ApplicationType> AppTypes { get; private set; } = new List<ApplicationType>();
 
         public Syncher(
             ILogger<Syncher> logger,
@@ -332,7 +332,7 @@ namespace PARR.AIHIT
         {
             if (string.IsNullOrEmpty(appName)) return null;
 
-            var existApp = await appService.GetByName(appName);
+            var existApp = await appService.GetByNameAsync(appName);
             if (existApp != null)
                 return existApp;
 

PARR.DAL/Extensions/GeneralExtesions.cs

@@ -0,0 +1,30 @@
+using System.Text.Encodings.Web;
+using System.Text.Json;
+using System.Text.Unicode;
+
+namespace PARR.DAL.Extensions
+{
+    public static class GeneralExtesions
+    {
+        /// <summary>
+        /// Преобразует объект в Json, с учетом Cyrillic
+        /// </summary>
+        /// <param name="value"></param>
+        /// <returns></returns>
+        public static string? ToJson(this object value)
+        {
+            if (value == null)
+                return null;
+
+            try
+            {
+                return JsonSerializer.Serialize(value, new JsonSerializerOptions { Encoder = JavaScriptEncoder.Create(UnicodeRanges.All, UnicodeRanges.Cyrillic) }); ;
+            }
+            catch// (Exception ex)
+            {
+                // todo: писать лог??? или и так пойдет
+                return null;
+            }
+        }
+    }
+}

PARR.DAL/Models/Application.cs

@@ -1,11 +1,6 @@
 using PARR.DAL.Models.Base;
-using System;
-using System.Collections.Generic;
 using System.ComponentModel.DataAnnotations;
 using System.ComponentModel.DataAnnotations.Schema;
-using System.Linq;
-using System.Text;
-using System.Threading.Tasks;
 
 namespace PARR.DAL.Models
 {
@@ -26,4 +21,3 @@ namespace PARR.DAL.Models
         public ICollection<ApplicationInHost> ApplicationsInHosts { get; set; } = new HashSet<ApplicationInHost>();
     }
 }
-}

PARR.DAL/Models/ApplicationInHost.cs

@@ -1,10 +1,5 @@
 using PARR.DAL.Models.Base;
-using System;
-using System.Collections.Generic;
 using System.ComponentModel.DataAnnotations.Schema;
-using System.Linq;
-using System.Text;
-using System.Threading.Tasks;
 
 namespace PARR.DAL.Models
 {

PARR.DAL/Models/Host.cs

@@ -11,7 +11,7 @@ namespace PARR.DAL.Models
         public Guid Id { get; set; }
         public DateTimeOffset DateCreated { get; set; }
         public DateTimeOffset? DateModified { get; set; }
-        public string HostName { get; set; }
+        public string? HostName { get; set; }
         public required string IP { get; set; }
         public string? RegionalEK { get; set; }
         public string? LinkEK { get; set; }

PARR.DAL/ParrDalInstaller.cs

@@ -16,8 +16,10 @@ namespace PARR.DAL
           );
 
             services.AddTransient<IHostService, HostService>();
-            //services.AddTransient<IUsersInLayersService, UsersInLayersService>();
+            services.AddTransient<IApplicationService, ApplicationService>();
-            //services.AddTransient<IAreaService, AreaService>();
+            services.AddTransient<IApplicationTypeService, ApplicationTypeService>();
+            services.AddTransient<IApplicationInHostService, ApplicationInHostService>();
+
             //services.AddTransient<IAreasInLayerService, AreasInLayerService>();
         }
     }

PARR.DAL/Services/Implementations/ApplicationInHostService.cs

@@ -0,0 +1,25 @@
+using Microsoft.EntityFrameworkCore;
+using Microsoft.Extensions.Logging;
+using PARR.DAL.Context;
+using PARR.DAL.Models;
+using PARR.DAL.Services.Abstracts;
+using PARR.DAL.Services.Interfaces;
+
+namespace PARR.DAL.Services.Implementations
+{
+    internal class ApplicationInHostService : BaseService<ApplicationInHost>, IApplicationInHostService
+    {
+        private readonly DataContext dataContext;
+        private readonly ILogger<ApplicationInHostService> logger;
+
+        public ApplicationInHostService(DataContext dataContext, ILogger<ApplicationInHostService> logger) : base(logger)
+        {
+            this.dataContext = dataContext;
+            this.logger = logger;
+        }
+
+        protected override DbSet<ApplicationInHost> EntitySet => dataContext.ApplicationsInHosts;
+
+        protected override DataContext EntitiContext => dataContext;
+    }
+}

PARR.DAL/Services/Implementations/ApplicationService.cs

@@ -0,0 +1,30 @@
+using Microsoft.EntityFrameworkCore;
+using Microsoft.Extensions.Logging;
+using PARR.DAL.Context;
+using PARR.DAL.Models;
+using PARR.DAL.Services.Abstracts;
+using PARR.DAL.Services.Interfaces;
+
+namespace PARR.DAL.Services.Implementations
+{
+    internal class ApplicationService : BaseService<Application>, IApplicationService
+    {
+        private readonly DataContext dataContext;
+        private readonly ILogger<ApplicationService> logger;
+
+        public ApplicationService(DataContext dataContext, ILogger<ApplicationService> logger) : base(logger)
+        {
+            this.dataContext = dataContext;
+            this.logger = logger;
+        }
+
+        protected override DbSet<Application> EntitySet => dataContext.Applications;
+
+        protected override DataContext EntitiContext => dataContext;
+
+        public async Task<Application?> GetByNameAsync(string appName)
+        {
+            return await EntitySet.FirstOrDefaultAsync(t => t.Name.ToLower() == appName.Trim().ToLower());
+        }
+    }
+}

PARR.DAL/Services/Implementations/ApplicationTypeService.cs

@@ -0,0 +1,25 @@
+using Microsoft.EntityFrameworkCore;
+using Microsoft.Extensions.Logging;
+using PARR.DAL.Context;
+using PARR.DAL.Models;
+using PARR.DAL.Services.Abstracts;
+using PARR.DAL.Services.Interfaces;
+
+namespace PARR.DAL.Services.Implementations
+{
+    internal class ApplicationTypeService : BaseService<ApplicationType>, IApplicationTypeService
+    {
+        private readonly DataContext dataContext;
+        private readonly ILogger<ApplicationTypeService> logger;
+
+        public ApplicationTypeService(DataContext dataContext, ILogger<ApplicationTypeService> logger) : base(logger)
+        {
+            this.dataContext = dataContext;
+            this.logger = logger;
+        }
+
+        protected override DbSet<ApplicationType> EntitySet => dataContext.ApplicationTypes;
+
+        protected override DataContext EntitiContext => dataContext;
+    }
+}

PARR.DAL/Services/Implementations/HostService.cs

@@ -21,21 +21,38 @@ namespace PARR.DAL.Services.Implementations
             this.logger = logger;
         }
 
-        public async Task<Host?> GetHostWithAppsAsync(string IP, string RegionalEK)//TODO
+        public async Task<Host?> GetHostWithAppsAsync(string IP, string RegionalEK)
         {
-            try
+
-            {
+            //try
-                var host = await EntitySet.FirstAsync(h => h.IP == IP && h.RegionalEK == RegionalEK);
+            //{
-                return host;
+            //    var host = await EntitySet.FirstAsync(h => h.IP == IP && h.RegionalEK == RegionalEK);
-            }
+            //    return host;
-            catch
+            //}
-            {
+            //catch
-                logger.LogInformation($"Не найден узел с IP адресом {IP} и региональным ЭК {RegionalEK}");
+            //{
-                return null;
+            //    logger.LogInformation($"Не найден узел с IP адресом {IP} и региональным ЭК {RegionalEK}");
-            }
+            //    return null;
+            //}
+            return await EntitySet
+                .Include(t => t.ApplicationsInHosts).ThenInclude(a => a.Application).ThenInclude(t => t.ApplicationType)
+                .FirstOrDefaultAsync(h => h.IP == IP && h.RegionalEK == RegionalEK);
         }
 
-        //public async Task<Host?> GetHostByRegionalEKAsync(string RegionalEK)
+        public async Task<Host?> GetHostWithAppsAsync(string IP, string linkEK, string regionalEK)
+        {
+            return await EntitySet
+               .Include(t => t.ApplicationsInHosts).ThenInclude(a => a.Application).ThenInclude(t => t.ApplicationType)
+               .FirstOrDefaultAsync(h => h.IP == IP && h.LinkEK == linkEK && h.RegionalEK == regionalEK);
+        }
+
+
+        public async Task<Host?> GetHostByIPAndRegionalEKAsync(string IP, string RegionalEK)
+        {
+            return await EntitySet.FirstOrDefaultAsync(h => h.IP == IP && h.RegionalEK == RegionalEK);
+        }
+
+        //public async Task<Host?> GetHostByRegionalEKAsync(string RegionalEK)И
         //{
         //    try
         //    {

PARR.DAL/Services/Interfaces/IApplicationInHostService.cs

@@ -0,0 +1,9 @@
+using PARR.DAL.Models;
+using PARR.DAL.Services.Interfaces.Base;
+
+namespace PARR.DAL.Services.Interfaces
+{
+    public interface IApplicationInHostService : IBaseService<ApplicationInHost>
+    {
+    }
+}

PARR.DAL/Services/Interfaces/IApplicationService.cs

@@ -0,0 +1,10 @@
+using PARR.DAL.Models;
+using PARR.DAL.Services.Interfaces.Base;
+
+namespace PARR.DAL.Services.Interfaces
+{
+    public interface IApplicationService : IBaseService<Application>
+    {
+        Task<Application?> GetByNameAsync(string appName);
+    }
+}

PARR.DAL/Services/Interfaces/IApplicationTypeService.cs

@@ -0,0 +1,9 @@
+using PARR.DAL.Models;
+using PARR.DAL.Services.Interfaces.Base;
+
+namespace PARR.DAL.Services.Interfaces
+{
+    public interface IApplicationTypeService : IBaseService<ApplicationType>
+    {
+    }
+}

PARR.DAL/Services/Interfaces/IHostService.cs

@@ -6,6 +6,7 @@ namespace PARR.DAL.Services.Interfaces
     public interface IHostService : IBaseService<Host>
     {
         Task<Host?> GetHostByIPAndRegionalEKAsync(string IP, string RegionalEK);
+        Task<Host?> GetHostWithAppsAsync(string IP, string linkEK, string regionalEK);
         //Task<Host?> GetHostByRegionalEKAsync(string LinkEK);
         //Task<bool> UpdateAsync(Host host);
     }