Servicestack - Grouping like services together - servicestack

Was wondering if there's a recommended best-practice way of grouping similar services together in what's becoming a larger and larger project. Say that most of my services can be lumped in either dealing with "Pro" data or "Amateur" data (the data goes way beyond a simple flag in a table, the data itself is totally different, from different tables, on the pro or amateur side.
I know I can add routes to my classes...
/pro/service1
/am/service2
It looks like I can put the DTOs in namespaces....
What about the Service.Interface items (Service and Factory classes). Would you put those into namespaces also?
Finally, is there a way for the metadata page to reflect these groupings? I started to go down this road, but all the services listed out in alphabetical order, and you couldn't see the route or namespace differences between service1 and service2.
thank you

If you want, you can split multiple Service implementations across multiple dlls as described on the Modularizing Services wiki.
You can safely group service implementation classes into any nested folder groupings without having any impact to the external services. But changing the namespaces on DTO's can have an effect if your DTO's make use of object, interfaces or abstract classes which emit type info containing full namespaces.
In ServiceStack v4.09+ (now on MyGet) the MetadataFeature includes the ability to customize the ordering of the metadata page, e.g you can reverse the order of the metadata pages with:
var metadata = (MetadataFeature)Plugins.First(x => x is MetadataFeature);
metadata.IndexPageFilter = page => {
page.OperationNames.Sort((x,y) => y.CompareTo(x));
};

Organising your large project:
For a complex service(s) I setup 4 projects in one solution.
AppHost, This takes care of the configuration of the service. (References Model, Service and Types)
Model, This is the database model (Does not reference other projects)
Service, This is the implementation of the service only, not the interfaces or DTOs (References Model and Types)
Types, This includes my Interfaces, DTOs and routes. (Does not reference other projects)
Having a separate Types library allows the distribution to clients, for example for use with the ServiceStack JsonServiceClient.
Yes you can namespace the Interfaces, DTOs and factory classes, any way you want. They will work as long as they are referenced in your service correctly.
If you are trying to separate more than one service, you should consider separating your service code into logical folders within the Service project. i.e.
/Service/Pro
/Service/Amateur
Wrap the outer code of your Service methods in a public partial static class MyServiceStackApplication, with an appropriate name. Then reference this as the assembly in the AppHost constructor. So for example:
Pro Service (Service Project/Pro/UserActions.cs)
public partial static class MyServiceStackApplication
{
public partial class Pro
{
public class UserActionsService : Service
{
public User Get(GetUserRequest request)
{
}
}
// ...
}
}
Pro Service (Service Project/Pro/OtherActions.cs)
public partial static class MyServiceStackApplication
{
public partial class Pro
{
public class OtherActionsService : Service
{
public Other Get(GetOtherRequest request)
{
}
}
// ...
}
}
Amateur Service (Service Project/Am/UserActions.cs)
public partial static class MyServiceStackApplication
{
public partial class Amateur
{
public class UserActionsService : Service
{
public User Get(GetUserRequest request)
{
}
}
// ...
}
}
etc.
You can see from the above code we can have multiple files, all separated out and organised, but one assembly for ServiceStack to reference in the AppHost:
public AppHost() : base("Pro & Amateur Services", typeof(MyServiceStackApplication).Assembly) {}
Using the reference to the MyServiceStackApplication assembly, and using the partial keyword allows you to organise the code into manageable groupings.
Metadata:
Unfortunately separating the metadata by namespace isn't supported. You could try and customize the MetaDataFeature yourself, but it does seem like a useful feature, being able to separate multiple services where they are hosted in the one ServiceStack application. I would suggest you raise a feature request.
Mythz is bringing out features faster than lightning. :) Seems like he has that covered in the next release and you should be able to apply a custom filter to HostContext.Metadata.OperationNamesMap.

Related

ServiceStack versioning - how to customize the request deserialization based on versioning

I am working on a new API where we have requirement for many to many versioning.
Old Client -> New Server
Old Server -> New client
and everything in
between
I've read some of the other posts about defensive programming and having DTOs that evolve gracefully... and we are definitely going to use that pattern in most cases.
However, when we have a breaking change for CreateCustomer and require CreateCustomer2 DTO, I would like to be able to customize the way SS resolves the type that is used to deserialize, otherwise we will be forced to use routes like this:
/api/v1/createcustomer
/api/v2/createcustomer
Where I would much rather keep it /api/createcustomer and let the version number live in the Header / Querystring / whatever (not looking for a debate here :) ).
Are there any examples of how to resolve the deserialization type dynamically in ServiceStack, based on a parameter other than route + verb?
Many thanks in advance
The recommended approach for versioning is to take advantage for the natural forwards compatibility of message-based services and extend existing services defensively so it can support multiple client versions and avoid create multiple versions of the same service.
If you still want to expose /api/v1 routes than I'd recommend doing it at the infrastructure level by using a reverse proxy to re-route /api/v1 and /api/v2 requests to different running instances of ServiceStack.
If you want to do the proxying in code you can use base.ResolveService<T>() or base.ExecuteRequest() to execute different Services in code and ServiceStack's built-in AutoMapping to populate different DTO's which could look something like:
[Route("/customers")]
public class CreateCustomers {
public int Version { get; set; }
}
public class CreateCustomersV1 { ... }
public class CreateCustomersV2 { ... }
public class CustomerServices : Service
{
public object Any(CreateCustomers request)
{
return request.Version == 1
? base.ExecuteRequest(request.ConvertTo<CreateCustomersV1>())
: base.ExecuteRequest(request.ConvertTo<CreateCustomersV2>())
}
}

Using MVC5 Repository pattern but need advice on where to put business logic

My latest MVC solution consists of an MVC5 site and a DAL class library that will contain a repository interface and class for each entity. I am trying to figure out where to place business logic for my entities such as CheckingAccount.Withdrawl or CheckingAccount.Deposit. Any suggestions? Should this be done within the Model folder within the MVC project while all of the repository classes are in my DAL?
Ideally you want to separate your actual business logic from your entities and abstract it away from your database or ORM as much as possible by creating a business logic layer and injecting your repository into your service/business logic layer using an IoC container and dependency injection.
The common approach is to create a separate class library for your business logic layer that remains agnostic of your UI layer (meaning your UI layer could be an MVC front end or even restful web service) and communicates via data transfer objects.
Here is a simple example:
MVC Controller / UI
public class AccountCheckingController : Controller
{
private readonly IAccountService AccountService;
public CheckingAccountController(IAccountService accountService)
{
this.AccountService accountService;
}
[HttpPost]
public ActionResult Deposit(decimal depositAmount)
{
...
DepositReceiptDto depositReceipt = this.accountServive.Deposit(accountId, depositAmount);
...
return new DepositViewModel {
Receipt = depositReceipt
}
}
}
Business Logic Class / Service (stored in a class library such as WebsiteName.Services or Website.BusinessLogic
public class AccountService : IAccountService
{
private readonly IAccountRepository Repository;
public AccountService(IAccountRepository repository)
{
this.Repository = repository;
}
public DepositReceiptDto Deposit(int accountId, decimal depositAmount)
{
// Perform actions against your repository/ORM here.
return new DepositReceiptDto {
DepositAmount = depositAmount,
User = UserDto,
Status = Status.Success
};
}
...
}
As you can see, by using this separation you can easily switch out your UI without having to perform much work.
I hope this helps.
If something is not an entity and is not a value object, then it's a service. Correct namespace for service depends on his level. Data-access services may be located in the Project.Dal or Project.Dal.Services. The good namespace for domain's service is the Project.Domain.Services.

Why is data access tightly coupled to the Service base in ServiceStack

I'm curious why the decision was made to couple the Service base class in ServiceStack to data access (via the Db property)? With web services it is very popular to use a Data Repository pattern to fetch the raw data from the database. These data repositories can be used by many services without having to call a service class.
For example, let's say I am supporting a large retail chain that operates across the nation. There are a number of settings that will differ across all stores like tax rates. Each call to one of the web services will need these settings for domain logic. In a repository pattern I would simply create a data access class whose sole responsibility is to return these settings. However in ServiceStack I am exposing these settings as a Service (which it needs to be as well). In my service call the first thing I end up doing is newing up the Setting service and using it inside my other service. Is this the intention? Since the services return an object I have to cast the result to the typed service result.
ServiceStack convenience ADO.NET IDbConnection Db property allows you to quickly create Database driven services (i.e. the most popular kind) without the overhead and boilerplate of creating a repository if preferred. As ServiceStack Services are already testable and the DTO pattern provides a clean endpoint agnostic Web Service interface, there's often not a lot of value in wrapping and proxying "one-off" data-access into a separate repository.
But at the same time there's nothing forcing you to use the base.Db property, (which has no effect if unused). The Unit Testing Example on the wiki shows an example of using either base.Db or Repository pattern:
public class SimpleService : Service
{
public IRockstarRepository RockstarRepository { get; set; }
public List<Rockstar> Get(FindRockstars request)
{
return request.Aged.HasValue
? Db.Select<Rockstar>(q => q.Age == request.Aged.Value)
: Db.Select<Rockstar>();
}
public RockstarStatus Get(GetStatus request)
{
var rockstar = RockstarRepository.GetByLastName(request.LastName);
if (rockstar == null)
throw HttpError.NotFound("'{0}' is no Rockstar".Fmt(request.LastName));
var status = new RockstarStatus
{
Alive = RockstarRepository.IsAlive(request.LastName)
}.PopulateWith(rockstar); //Populates with matching fields
return status;
}
}
Note: Returning an object or a strong-typed DTO response like RockstarStatus have the same effect in ServiceStack, so if preferred you can return a strong typed response and avoid any casting.

How to specify and organize OXM_METADATA_SOURCE in glassfish v4 MOXy Provider?

I am a fan of both Glassfish and MOXy, and it's good news for me that MOXy had been bundled into Glassfish v4.
I had read and tried a few of MOXy examples on the internet, I like the dynamic OXM_META_DATA_SOURCE part, since while providing RESTful services, the "client perspective" is very flexible than domain classes.
So here is the problem:
Different RESTful services can have different views from same domain classes, and in my work it's very common case. So there can be a lot of binding OXM metadata files for every service. And as we know a single OXM metadata file can only correspond to a single java package. So there will be much more OXM metadata files to maintain.
Back to JAX-RS, Is there any framework to design patterns or best practices to finish the mapping between OXM metadata file set and the service itself?
You can try new feature called Entity Filtering which has been introduced in Jersey 2.3. Even though Entity Filtering is not based on OXM_META_DATA_SOURCE you can achieve your goal with it:
Let's assume you have a following domain class (annotations are custom entity-filtering annotations):
public class Project {
private Long id;
private String name;
private String description;
#ProjectDetailedView
private List<Task> tasks;
#ProjectAnotherDetailedView
private List<User> users;
// ...
}
And, of course, some JAX-RS resources, i.e.:
#Path("projects")
#Produces("application/json")
public class ProjectsResource {
#GET
#Path("{id}")
public Project getProject(#PathParam("id") final Long id) {
return ...;
}
// ...
}
Now, we have 2 detailed views defined on domain class (via annotations) and the resource class. If you annotate getProject resource method with:
#ProjectDetailedView - returned entity would contain id, name, description AND a list of tasks from Project
#ProjectAnotherDetailedView - returned entity would contain id, name, description AND a list of users from Project
If you leave the resource method un-annotated the resulting entity would contain only: id, name, description.
You can find more information about Entity Filtering in the User Guide or you can directly try it in our example: entity-filtering.
Note 1: Entity Filtering works only with JSON media type (via MOXy) at the moment. Support for other media types / providers is planned to be added in the future.
Note 2: Jersey 2.3 is not integrated into any (promoted) build of GF 4.0. The next Jersey version that should be part of GF 4.0 is 2.4. We plan to release 2.4 in the next few weeks.

Domain driven design external systems and technical dependencies

I am designing a system using domain driven design concepts and I am struggling with a few things. The "domain" is essentially a business system for the company I work for. I am also using dependency injection. So, in my model I have things related to any typical business system (Employee, Order, Invoice, Deposit, etc..). Right now I am trying to create a cash posting application in which users (aka Employees) can create deposits and apply them to unpaid invoices. The problem that I am having is that we are also using an external business system (Microsoft Dynamics Nav) to handle our accounting transactions. So essentially I am dealing with two different databases. So, for the cash posting application I have modeled the domain objects Deposit and DepositLine. I also have in my domain an IDepositRepository interface that is responsible for persisting the deposits. To get a deposit from the system I just want to grab it directly from the database. However, in order to create a deposit I have to use the Dynamics Nav web services because there is certain logic that gets executed behind the scenes that I don't know about. I started looking at the concept of an Anti Corruption layer in which I could translate my version of the deposit object into a deposit object suitable for the web service. So here is what I am envisioning right now:
Domain Layer
- Models
- Deposit
- DepositLine
- Repositories
- IDepositRepository
Infrastructure Layer
- Data
- Repositories
- DepositRepository
- DynamicsNav
- Services
- INavCashManagementService
- Translators
- IDepositTranslator
- Adapters
- INavAdapter
Now I thought i might implement the DepositRepository like so:
public class DepositRepository
{
private INavCashManagementService navCashManagementService;
public DepositRepository(INavCashManagementService navCashManagementService)
{
this.navCashManagementService = navCashManagementService;
}
public Deposit GetDeposit(int id)
{
// use nhibernate to get directly from the database
}
public void SaveDeposit(Deposit deposit)
{
this.navCashManagementService.CreateDeposit(deposit);
}
}
First of all, is this an appropriate design? My next problem is that users are also going to have to "Post" deposits. The Nav web services will also have to be used to run the posting routine. But, this is more of a business process rather than a persistence issue, so I don't see it fitting into the repository. So I am wondering how/where I should call the posting routine. Should I create a domain service like this:
public class CashPostingDomainService
{
private INavCashManagementService navCashManagementService;
public CashPostingDomainService(INavCashManagementService navCashManagementService)
{
this.navCashManagementService = navCashManagementService;
}
public void PostDeposits()
{
this.navCashManagementService.PostDeposits();
}
}
One confusion I have with domain driven design is external dependencies. Doesn't the CashPostingDomainService class now have an external dependency on Nav? I know the implementation isn't in the domain layer, but doesn't the interface itself make it a dependency? The same goes with other technical concerns like sending emails. If I have an IEmailService interface and want to send an email once the deposits are posted, would I inject the interface into the CashPostingDomainService class? Or would that be part of the application workflow? So which one of these options make the most sense (if any):
1
public class DepositController
{
private ICashPostingDomainService cashPostingDomainService;
private IEmailService emailService;
public DepositController(
ICashPostingDomainService cashPostingDomainService,
IEmailService emailService)
{
this.cashPostingDomainService = cashPostingDomainService;
this.emailService = emailService;
}
public void PostDeposits()
{
this.cashPostingDomainService.PostDeposits();
this.emailService.NotifyDepositsPosted();
}
}
2
public class DepositController
{
private ICashPostingDomainService cashPostingDomainService;
public DepositController(
ICashPostingDomainService cashPostingDomainService)
{
this.cashPostingDomainService = cashPostingDomainService;
}
public void PostDeposits()
{
this.cashPostingDomainService.PostDeposits();
}
}
public class CashPostingDomainService
{
private INavCashManagementService navCashManagementService;
private IEmailService emailService;
public CashPostingDomainService(
INavCashManagementService navCashManagementService,
IEmailService emailService)
{
this.navCashManagementService = navCashManagementService;
this.emailService = emailService;
}
public void PostDeposits()
{
this.navCashManagementService.PostDeposits();
this.emailService.NotifyDepositsPosted();
}
}
Thanks for the help!
is this an appropriate design?
It seems fine to me. The important thing is for your Repository to stay oblivious of the Nav side of things and let the anticorruption layer handle that. You might want to have a look here for a similar example.
I know the implementation isn't in the domain layer, but doesn't the
interface itself make it a dependency?
You may have that feeling because the name of your (supposedly agnostic) service interface contains "Nav". To reflect a service abstraction that could have Nav or any other ERP as an implementation, you should rename it to ICashManagementService.
If I have an IEmailService interface and want to send an email once
the deposits are posted, would I inject the interface into the
CashPostingDomainService class? Or would that be part of the
application workflow?
It's your architectural decision to choose one or the other.
Option 1. means that sending an email is an intrinsic part of the deposit posting domain operation. If you take your domain module and reuse it in another application, posting deposits will automatically result in sending an email whatever that application is about. This might be the right thing to do in your context, or you might want to make things a little more generic (like, sending feedback after the operation but not deciding in the domain service whether this feedback should be mail, a log file, etc.)
Option 2. means that the sequence of events that happen after posting the deposits is application specific, that is at the use case level rather than business/domain level. It is up to the Controller (or Application Service) to decide which actions to take -send an email or anything else. Consequently, different applications based around your domain layer could decide to take different actions. This also means possible code duplication between these applications if several of them chose to send mails.

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