I need to set global TTL to each entity I have and it should be configurable in one place.
There is an opportunity to do this via #RedisHash annotation:
#RedisHash(value = "persons",timeToLive = 100)
public class Person{
...
}
or I can have a field
public class Person{
#TimeToLeave
Long ttl;
}
but in this case I can't change it in one place and it's not really comfortable
to maintain it.
I have a property in applicaiton.properties:
app.redis.ttl=100
and it will be awesome to have an opportunity to change it on property level.
You can configure settings by creating a subclass of KeyspaceConfiguration and configuring #EnableRedisRepositories. There's no property-based configuration for global TTL.
#EnableRedisRepositories(keyspaceConfiguration = MyKeyspaceConfiguration.class)
public class MyConfig {
}
public class MyKeyspaceConfiguration extends KeyspaceConfiguration {
#Override
public boolean hasSettingsFor(Class<?> type) {
return true;
}
#Override
public KeyspaceSettings getKeyspaceSettings(Class<?> type) {
KeyspaceSettings keyspaceSettings = new KeyspaceSettings(type, "my-keyspace");
keyspaceSettings.setTimeToLive(3600L);
return keyspaceSettings;
}
}
Deriving from KeyspaceConfiguration is intended to provide Iterable<KeyspaceSettings> initialConfiguration() in the first place but since you want to apply that settings to all classes, the in-place creation of KeyspaceSettings makes more sense.
You also might want to cache the KeyspaceSettings to not create instances all over so Java 8's Map.computeIfAbsent(…) would be a good fit.
Related
Environment:
.Net, SQL Server, WinForms Desktop
Control Database (db1)
Customer Databases (db2, db3, db4, etc.)
Background:
Each of our customers requires their own database. It's a contractual obligation due to compliance with standards in certain industries. Certain users of our application only have access to specific databases.
Scenario:
The application user's username gets passed into our control database (db1) from the app on load. There's a lookup in there that determines what customer this user has access to and returns connection string info for connecting to the database of the determined customer (db2 or db3 or db4 or etc.) to be used for the life of the runtime. All of my business logic is in a DAL, as it should be, in a .Net class library.
Suggestions on the best way/ways to get the connection string information into the DAL WITHOUT passing into every constructor/method that is called on the DAL.
I came up with one possible solution, but want to pick your brains to see if there's another or better way.
Possible Solutions:
A Global module in the DAL that has public fields like "dbServer" and "dbName".
Set those and then use the DAL as needed. They would need to be set each time the DAL is used throughout the application, but at least I don't have to make the signature of every single constructor and method require connection string information.
A settings file (preferably XML) that the app writes to after getting the connection info and the DAL reads from for the life of the runtime.
Thoughts and/or suggestions? Thanks in advance.
A set up like this might help. If you are going the IoC way, then you can remove the parameterized constructor and make Connection object a dependency too. However, you will need to feed your dependency injection provider in code since connection string comes from database.
public class User
{
public string ConnectionString
{
get; set;
}
}
public class SomeBusinessEntity
{
}
public class CallerClass
{
public IBaseDataAccess<SomeBusinessEntity> DataAccess
{
get;
set;
}
public void DoSomethingWithDatabase(User user)// Or any other way to access current user
{
// Either have specific data access initialized
SpecificDataAccess<SomeBusinessEntity> specificDataAccess = new SpecificDataAccess<SomeBusinessEntity>(user.ConnectionString);
// continue
// have dependency injection here as well. Your IoC configuration must ensure that it does not kick in until we get user object
DataAccess.SomeMethod();
}
}
public interface IBaseDataAccess<T>
{
IDbConnection Connection
{
get;
}
void SomeMethod();
// Other common stuff
}
public abstract class BaseDataAccess<T> : IBaseDataAccess<T>
{
private string _connectionString;
public BaseDataAccess(string connectionString)
{
_connectionString = connectionString;
}
public virtual IDbConnection Connection
{
get
{
return new SqlConnection(_connectionString);
}
}
public abstract void SomeMethod();
// Other common stuff
}
public class SpecificDataAccess<T> : BaseDataAccess<T>
{
public SpecificDataAccess(string connectionString) : base(connectionString)
{
}
public override void SomeMethod()
{
throw new NotImplementedException();
}
public void SomeSpecificMethod()
{
using (Connection)
{
// Do something here
}
}
}
Create a ConnectionStringProvider class that will provide you the connection string
public class ConnectionStringProvider
{
// store it statically so that every instance of connectionstringprovider
// uses the same value
private static string _customerConnectionString;
public string GetCustomerConnectionString()
{
return _customerConnectionString;
}
public void SetCustomerConnectionString(string connectionString)
{
_customerConnectionString = connectionString;
}
}
Using ConnectionStringProvider in your DAL
public class MyCustomerDAL
{
private ConnectionStringProvider _connectionStringProvider;
public MyCustomerDAL()
{
_connectionStringProvider = new ConnectionStringProvider();
}
public void UpdateSomeData(object data)
{
using (var con = new SqlConnection(
connectionString: _connectionStringProvider.GetCustomerConnectionString()))
{
//do something awesome with the connection and data
}
}
}
Setting/changing the connection string
new ConnectionStringProvider()
.SetCustomerConnectionString(connString);
Note
The reason i chose to use method instead of a get/set property in ConnectionStringProvider is because maybe in the future you decide to read/write these from a file, and while you could read/write from file in a property it's misleading to your consumer who thinks that a property will be a simple performance-less hit.
Using a function tells your consumer there might be some performance hit here, so use it wisely.
A little abstration for unit testing
Here is a slight variation that will enable you to abstract for unit testing (and eventually IoC)
public class MyCustomerDAL
{
private IConnectionStringProvider _connectionStringProvider;
public MyCustomerDAL()
{
//since not using IoC, here you have to explicitly new it up
_connectionStringProvider = new ConnectionStringProvider();
}
//i know you don't want constructor, i included this to demonstrate how you'd override for writing tests
public MyCustomerDAL(IConnectionStringProvider connectionStringProvider)
{
_connectionStringProvider = connectionStringProvider;
}
public void UpdateSomeData(object data)
{
using (var con = new SqlConnection(
connectionString: _connectionStringProvider.GetCustomerConnectionString()))
{
//do something awesome with the connection and data
}
}
}
// this interface lives either in a separate abstraction/contracts library
// or it could live inside of you DAL library
public interface IConnectionStringProvider
{
string GetCustomerConnectionString();
void SetCustomerConnectionString(string connectionString);
}
public class ConnectionStringProvider : IConnectionStringProvider
{
// store it statically so that every instance of connectionstringprovider uses the same value
private static string _customerConnectionString;
public string GetCustomerConnectionString()
{
return _customerConnectionString;
}
public void SetCustomerConnectionString(string connectionString)
{
_customerConnectionString = connectionString;
}
}
Appendix A - Using IoC and DI
Disclaimer: the goal of this next piece about IoC is not to say one way is right or wrong, it's merely to bring up the idea as another way to approach solving the problem.
For this particular situation Dependency Injection would make your solving the problem super simple; specifically if you were using an IoC container combined with constructor injection.
I don't mean it would make the code more simple, that would be more or less the same, it would make the mental side of "how do I easily get some service into every DAL class?" an easy answer; inject it.
I know you said you don't want to change the constructor. That's cool, you don't want to change it because it is a pain to change all the places of instantiation.
However, if everything were being created by IoC, you would not care about adding to constructors because you would never invoke them directly.
Then, you could add services like your new IConnectionStringProvider right to the constructor and be done with it.
I have 1 interface named IProcessor having multiple implementations like ABCProcessor, PQRProcessor.
I want to make use of specific processor based on external parameters. How can I achive the same using StructureMap.
I am looking at named instances for the same.
You could use a factory pattern:
public interface IProcessorFactory
{
IProcessor Create(int dropDownValue);
}
public class ProcessorFactory : IProcessorFactory
{
private readonly IContainer _container;
public ProcessorFactory(IContainer container)
{
_container = container;
}
public IProcessor Create()
{
if(//your condition)
return _container.GetInstance<ABCProcessor>();
_container.GetInstance<PQRProcessor>();
}
}
(or simply inject the required dependencies instead of the container)
and then simply
private readonly IProcessorFactory _processorFactory;
public MvcController(IProcessorFactory processorFactory)
{
_processorFactory = processorFactory;
}
public void Method()
{
var processor = _processorFactory.Create();
}
The best solution to your problem is to hide the knowledge of the existence of multiple implementations and the selection between them from the consumer by implementing a proxy implementation for IProcessor:
public sealed ProxyProcessor : IProcessor
{
private readonly ABCProcessor abc;
private readonly PQRProcessor pqr;
private readonly IProcessorConfig config;
public ProxyProcessor(ABCProcessor abc, PQRProcessor pqr, IProcessorConfig config) {
this.abc = abc;
this.pqr = pqr;
this.config = config;
}
// Implement IProcessor methods to forward to the CurrentProcessor.
public void Process() => CurrentProcessor.Process();
private IProcessor CurrentProcessor => config.ProcessorType == "ABC" ? abc : pqr;
}
By doing this you can delegate to the correct implementation at runtime while the consumer stays oblivious to the fact that you make a decision at runtime about this. Now instead of injecting either an ABCProcessor or PQRProcessor into the consumers, you now inject a ProxyProcessor into the consumers. For instance, this is how the object graph for the ProxyProcessor could look like:
IProcessor processor =
new ProxyProcessor(
abc: new ABCProcessor(),
pqr: new PQRProcessor(),
config: new SqlProcessorConfig("constr"));
Note that this solution has several benefits over the use of a factory, such as:
It prevents having to make any changes to the consumers; the consumers stay oblivious.
It prevents introducing unneeded complexity into the consumers; with the factory approach, consumers have to deal with with an extra dependency. This complicates code and tests.
It causes object graphs to be constructed in a delayed fashion, which complicates verification of object graphs.
Please read this article if you want to know more about why factories hardly ever are the right abstraction.
How do you perform property injection with Simple Injector.
The with Ninject you do is as per bellow:
[Inject]
public IUnitOfWork UnitOfWork { get; set; }
How can I do the equivalent to this with Simple Injector. I tried finding a solution online but had no luck.
Why do I want to use Property Injection?
I want to use property injection to set up unit of work in my base controller so that it will create a new unit of work OnActionExecuting and commit the changes OnResultExecuted. It also means I don't have to pass in the UoW with each new controller I create through the constructor.
Another option is to use the RegisterInitializer method:
container.RegisterInitializer<BaseControllerType>(controller =>
{
controller.UnitOfWork = container.GetInstance<IUnitOfWork>();
}
It keeps all configuration in your composition root and does not pollute your code base with all kinds of attributes.
Update: (as promised)
While this is a direct answer to your question I have to provide you with a better option, because the usage of a base class for this is a IMO not the correct design, for multiple reasons.
Abstract classes can become real PITA classes as they tend to grow towards a god class which has all kinds of cross cutting concerns
An abstract class, especially when used with property injection, hides the needed dependencies.
With focus on point 2. When you want to unit test a controller which inherits from the base controller, you have no way of knowing that this controller is dependent on IUnitOfWork. This you could solve by using constructor injection instead of property injection:
protected abstract class BaseController : Controller
{
protected readonly IUnitOfWork uoW;
protected BaseController (IUnitOfWork uoW)
{
this.uoW = uoW;
}
}
public class SomeController : BaseController
{
public SomeController(IUnitOfWork uoW) : base(uoW) { }
}
While this solves point 2, point 1 is still lurking. The main reason you're wanting this, as you say, is because you do not want to commit your changes in every Action method. Changes must just be saved by the context when the request is done. And thinking about design in this way is a good thing, because Saving changes is, or can be seen as a cross cutting concern and the way you're implementing this is more or less known as AOP.
If it's comes to AOP, especially if you're working with atomic actions in the action methods of your controllers, there is a far better, more SOLID and more flexible design possible which deals with this very nicely.
I'm referring to the Command/Handler pattern which is described in great detail here (also read this for the query part of your application).
With this patterns you don't inject a generic IUnitOfWork abstraction, but inject the specific needed ICommandHandler<TCommand> abstractions.
The action methods would fire the responsible commandhandler for this specific action. All commandhandlers can simple be decorated by a single open-generic SaveChangesCommandHandlerDecorator, 'ValidationDecorator', 'CheckPermissionsDecorator', etc...
A quick example:
public class MoveCustomerCommand
{
public int CustomerId;
public Address NewAddress;
}
public class MoveCustomerCommandHandler : ICommandHandler<MoveCustomerCommand>
{
public void Handle(MoveCustomerCommand command)
{
// retrieve customer from database
// change address
}
}
public class SaveChangesCommandHandlerDecorator<TCommand> : ICommandHandler<TCommand>
{
private readonly ICommandHandler<TCommand> decoratee;
private readonly DbContext db;
public SaveChangesCommandHandlerDecorator(
ICommandHandler<TCommand> decoratee, DbContext db)
{
this.decoratee = decoratee;
this.db = db;
}
public void Handle(TCommand command)
{
this.decoratee.Handle(command);
this.db.SaveChanges();
}
}
// Register as
container.Register(typeof(ICommandHandler<>), new []{Assembly.GetExecutingAssembly() });
container.RegisterDecorator(typeof(ICommandHandler<>),
typeof(SaveChangesCommandHandlerDecorator<>));
// And use in controller as
public ActionResult MoveCustomer(int customerId, Address address)
{
var command = new MoveCustomerCommand
{ CustomerId = customerId, Address = address };
this.commandHandler.Handle(command);
return View(new ResultModel());
}
This keeps your controllers clean and let it do what it must do, namely be the layer between the business logic (the commandhandler implementation in this case) and the view.
Need to create the following:
First create the attribute class
[System.AttributeUsage(System.AttributeTargets.Property]
public class Inject : Attribute
{
}
Then create a custom property behavior
class PropertySelectionBehavior<TAttribute> : IPropertySelectionBehavior
where TAttribute : Attribute
{
public bool SelectProperty(Type type, PropertyInfo prop)
{
return prop.GetCustomAttributes(typeof(TAttribute)).Any();
}
}
Finally tell the container to use custom behavior
container.Options.PropertySelectionBehavior = new PropertySelectionBehavior<Inject>();
All that is left to do is decorate the property with the attribute
[Inject]
public IUnitOfWork UnitOfWork { get; set; }
I have spent the last day trying to work out which pattern best fits my specific scenario and I have been tossing up between the State Pattern & Strategy pattern. When I read examples on the Internet it makes perfect sense... but it's another skill trying to actually apply it to your own problem. I will describe my scenario and the problem I am facing and hopefully someone can point me in the right direction.
Problem: I have a base object that has different synchronization states: i.e. Latest, Old, Never Published, Unpublished etc. Now depending on what state the object is in the behaviour is different, for example you cannot get the latest version for a base object that has never been published. At this point it seems the State design pattern is best suited... so I have implemented it and now each state has methods such as CanGetLatestVersion, GetLatestVersion, CanPublish, Publish etc.
It all seems good at this point. But lets say you have 10 different child objects that derive from the base class... my solution is broken because when the "publish" method is executed for each state it needs properties in the child object to actually carry out the operation but each state only has a reference to the base object. I have just spent some time creating a sample project illustrating my problem in C#.
public class BaseDocument
{
private IDocumentState _documentState;
public BaseDocument(IDocumentState documentState)
{
_documentState = documentState;
}
public bool CanGetLatestVersion()
{
return _documentState.CanGetLatestVersion(this);
}
public void GetLatestVersion()
{
if(CanGetLatestVersion())
_documentState.CanGetLatestVersion(this);
}
public bool CanPublish()
{
return _documentState.CanPublish(this);
}
public void Publish()
{
if (CanPublish())
_documentState.Publish(this);
}
internal void Change(IDocumentState documentState)
{
_documentState = documentState;
}
}
public class DocumentSubtype1 : BaseDocument
{
public string NeedThisData { get; set; }
}
public class DocumentSubtype2 : BaseDocument
{
public string NeedThisData1 { get; set; }
public string NeedThisData2 { get; set; }
}
public interface IDocumentState
{
bool CanGetLatestVersion(BaseDocument baseDocument);
void GetLatestVersion(BaseDocument baseDocument);
bool CanPublish(BaseDocument baseDocument);
bool Publish(BaseDocument baseDocument);
SynchronizationStatus Status { get; set; }
}
public class LatestState : IDocumentState
{
public bool CanGetLatestVersion(BaseDocument baseDocument)
{
return false;
}
public void GetLatestVersion(BaseDocument baseDocument)
{
throw new Exception();
}
public bool CanPublish(BaseDocument baseDocument)
{
return true;
}
public bool Publish(BaseDocument baseDocument)
{
//ISSUE HERE... I need to access the properties in the the DocumentSubtype1 or DocumentSubType2 class.
}
public SynchronizationStatus Status
{
get
{
return SynchronizationStatus.LatestState;
}
}
}
public enum SynchronizationStatus
{
NeverPublishedState,
LatestState,
OldState,
UnpublishedChangesState,
NoSynchronizationState
}
I then thought about implementing the state for each child object... which would work but I would need to create 50 classes i.e. (10 children x 5 different states) and that just seems absolute crazy... hence why I am here !
Any help would be greatly appreciated. If it is confusing please let me know so I can clarify!
Cheers
Let's rethink this, entirely.
1) You have a local 'Handle', to some data which you don't really own. (Some of it is stored, or published, elsewhere).
2) Maybe the Handle, is what we called the 'State' before -- a simple common API, without the implementation details.
3) Rather than 'CanPublish', 'GetLatestVersion' delegating from the BaseDocument to State -- it sounds like the Handle should delegate, to the specific DocumentStorage implementation.
4) When representing external States or Storage Locations, use of a separate object is ideal for encapsulating the New/Existent/Deletion state & identifier, in that storage location.
5) I'm not sure if 'Versions' is part of 'Published Location'; or if they're two independent storage locations. Our handle needs a 'Storage State' representation for each independent location, which it will store to/from.
For example:
Handle
- has 1 LocalCopy with states (LOADED, NOT_LOADED)
- has 1 PublicationLocation with Remote URL and states (NEW, EXIST, UPDATE, DELETE)
Handle.getVersions() then delegates to PublicationLocation.
Handle.getCurrent() loads a LocalCopy (cached), from PublicationLocation.
Handle.setCurrent() sets a LocalCopy and sets Publication state to UPDATE.
(or executes the update immediately, whichever.)
Remote Storage Locations/ Transports can be subtyped for different methods of accessing, or LocalCopy/ Document can be subtyped for different types of content.
THIS, I AM PRETTY SURE, IS THE MORE CORRECT SOLUTION.
[Previously] Keep 'State' somewhat separate from your 'Document' object (let's call it Document, since we need to call it something -- and you didn't specify.)
Build your heirarchy from BaseDocument down, have a BaseDocument.State member, and create the State objects with a reference to their Document instance -- so they have access to & can work with the details.
Essentially:
BaseDocument <--friend--> State
Document subtypes inherit from BaseDocument.
protected methods & members in Document heirarchy, enable State to do whatever it needs to.
Hope this helps.
Many design patterns can be used to this kind of architecture problem. It is unfortunate that you do not give the example of how you do the publish. However, I will state some of the good designs:
Put the additional parameters to the base document and make it
nullable. If not used in a document, then it is null. Otherwise, it
has value. You won't need inheritance here.
Do not put the Publish method to the DocumentState, put in the
BaseDocument instead. Logically, the Publish method must be part
of BaseDocument instead of the DocumentState.
Let other service class to handle the Publishing (publisher
service). You can achieve it by using abstract factory pattern. This
way, you need to create 1:1 document : publisher object. It may be
much, but you has a freedom to modify each document's publisher.
public interface IPublisher<T> where T : BaseDocument
{
bool Publish(T document);
}
public interface IPublisherFactory
{
bool Publish(BaseDocument document);
}
public class PublisherFactory : IPublisherFactory
{
public PublisherFactory(
IPublisher<BaseDocument> basePublisher
, IPublisher<SubDocument1> sub1Publisher)
{
this.sub1Publisher = sub1Publisher;
this.basePublisher = basePublisher;
}
IPublisher<BaseDocument> basePublisher;
IPublisher<SubDocument1> sub1Publisher;
public bool Publish(BaseDocument document)
{
if(document is SubDocument1)
{
return sub1Publisher.Publish((SubDocument1)document);
}
else if (document is BaseDocument)
{
return basePublisher.Publish(document);
}
return false;
}
}
public class LatestState : IDocumentState
{
public LatestState(IPublisherFactory factory)
{
this.factory = factory;
}
IPublisherFactory factory;
public bool Publish(BaseDocument baseDocument)
{
factory.Publish(baseDocument);
}
}
Use Composition over inheritance. You design each interface to each state, then compose it in the document. In summary, you can has 5 CanGetLatestVersion and other composition class, but 10 publisher composition class.
More advancedly and based on the repository you use, maybe you can use Visitor pattern. This way, you can has a freedom to modify each publishing methods. It is similiar to my point 3, except it being declared in one class. For example:
public class BaseDocument
{
}
public class SubDocument1 : BaseDocument
{
}
public class DocumentPublisher
{
public void Publish(BaseDocument document)
{
}
public void Publish(SubDocument1 document)
{
// do the prerequisite
Publish((BaseDocument)document);
// do the postrequisite
}
}
There may be other designs available but it is dependent to how you access your repository.
I am trying to map my collections with FNHib automapping. The problems that I want to solve are:
1) I want all my collections in the project to be mapped via private field. How can I say that globally?
2) Is there any way to automap bidirectional relationship without explicitly overriding each of my entities.
class OrganizationEntity example:
private ISet<> _collectionWarehouse;
public virtual IEnumerable<WarehouseEntity> CollectionWarehouse
{
get{return _collectionWarehouse; }
set{_collectionWarehouse = new HashedSet<WarehouseEntity>((ICollection<WarehouseEntity>)value)}
}
Class WarehouseEntity example:
public virtual OrganizationEntity Organization{get;set;}
You can map your collections to a private field 'globally' with the following convention:
// assumes camel case underscore field (i.e., _mySet)
public class CollectionAccessConvention : ICollectionConvention
{
public void Apply(ICollectionInstance instance) {
instance.Access.CamelCaseField(CamelCasePrefix.Underscore);
}
}
Whenever you want to set a 'global' automap preference in FNH, think conventions. The you use the IAutoOverride on a given class map if you need to.
As far has the set (a HashSet is usually what I really want also) part, the last time I had to do some mapping, I did need to do an override, like:
public class ActivityBaseMap : IAutoMappingOverride<ActivityBase>
{
public void Override(AutoMapping<ActivityBase> m)
{
...
m.HasMany(x => x.Allocations).AsSet().Inverse();
}
}
I do agree that should translate into a convention though, and maybe you can do that these days. Please post if you figure it out.
HTH,
Berryl
CODE TO USE A HASHSET as an ICollection =================
public virtual ICollection<WarehouseEntity> Wharehouses
{
get { return _warehouses ?? (_warehouses = new HashSet<WarehouseEntity>()); }
set { _warehouses = value; }
}
private ICollection<WarehouseEntity> _warehouses;