Remote Context

Vasat supports microservices and can have elements of business logic scattered amongst multiple servers.

In some cases having a Data Model reside on one server, but be used on another server is desirable.

A RemoteModelContext[A] allows for this very easily.

@JSONModel // Makes the mode have a JSON representation
case class Account(
    name:String,
    address:String
)

@RemoteAuto // generates the ModelContext
class ArticleRepo(val remoteHost:RemoteSignedWebservice) extends RemoteContext[Account]

Similar to a DBModelContext. Using a Macro is the quickest way to create a RemoteModelContext.

Once created, The location of the remoteHost needs to be specified. This is the Vasat server that stores the object in question.

A simple RemoteSginedWebservice on a play project can look like this:

@Singleton
class RemoteHost @Inject()(val siteInitService:SiteInitService) extends RemoteSignedWebservice{

  val remoteHost = "https://my_account_site"

  override def site = siteInitService.siteObject
}

Configuring the 'Remote'

Route

The remote site requires a special route that must be enabled.

routes

POST    /crud      vasat.play.controllers.RemoteCRUDController.doCRUD

Authentication

RemoteModelContexts can work in 2 ways with regards to authentication

1. Web / OAuth

If the 'local' vasat server is exposing the remote servers endpoint. eg:

https://mylocal_site/api/Account -> https://my_account_site/api/Account

The access token used on the local request is simply forwarded to the remote

2. Site Authentication

Through the trust policy of the Site objects between the local and remote Vasat a level of access can be defined. This can be full access where Site.trusted = true or partial access where the Site.trusted = false and a list of ACL levels are defined in the site definition.

This is used for when the ModelContext is being used directly in code on the 'local' server

val accountRemoteRepo = new AccountRepository(...)

val a:Account = ???
accountRemoteRepo.writeObject("abc-123",a).andThenMap(_ => 
    println("Saved")
) // request is sent to remote server and written there