How i can call a BS through a BO that are in another namespace ?

In general, the following concepts should be noted when working with REST.

When you create a Namespace Definition, unless you specify otherwise, a default Web Application will be defined. If you namespace is named "Application-DEV" then when you save the Namespace definition a Web Application will be created in the form /csp/application-dev/.

Likewise, you are likely to have a QC and PROD namespaces as well and the default Web Applications will be /csp/application-qc/ and /csp/application-prod/

This default Web Application is used by by the "Management Portal" and  "View Class Documentation"

If you design normal CSP Pages bound to a class in your application then the default Web Application will be used. You can customise this by specifying your own Login Page and a couple of other properties.

When it comes to REST, and specifically the REST Dispatcher you will define one or more Web Applications. All of which point to the same namespace.

For example, if you have three namespaces, DEV, QC and PRD and you have a Business Service and you want to channel HTTP Requests based on 3 different User Roles then, for each namespace, you define a Web Application for each Role for each namespace.

Lets assume that the roles are User, Administrator and SuperUser then you would create the following Web Applications:

/csp/dev/user/

/csp/dev/administrator/

/csp/dev/superuser/

generically the format is /csp/{namespace_abbreviation}/{role}

When you define these Web Applications you need to have written a class that inherits from %CSP.REST

In you Interface Production you add three business services that are named "User Service", "Administrator Service" and "SuperUser Service". Every Service Production Item has the same underlying Business Service Class. In you Web Application Definition there is a field called REST Dispatcher. You enter the name of your REST Dispatcher class there. The rest of the form greys out

In your Rest Dispatcher class, lets call it REST.Dispatcher there is an XDATA routing block that defines what to do when  different HTTP Methods are used to pass in your request. They are very simply POST, PUT, DELETE, GET and GET with parameters (essentially a search)

Lets assume that you are going to InsertData, UpdataData, DeleteData, FetchData, SearchData

Then the XDATA Route Maps would look something like this:

<Route URL="/InsertData" Method="POST" Call "InsertDataMethod" />

<Route URL="/UpdateData/:id" Method="PUT" call "UpdateDataMethod" />

<Route URL="/SearchData/:id" Method="GET" call "SearchDataMethod" />

The methods are defined in the REST.Dispatcher class and one of the variables available to you is %request.URL which is the full /csp/{ns}/{role}/ and from this you can determine which Production Service Name you want to pass the request to.

So you Production Item Name turns out to be "Administrator Service" and is held in a variable tProductionItem

you then execute the following line of code:

Set tSC = ##class(Ens.Director).CreateBusinessService(tProductionItem,.tService) if 'tSC quit

You then create your Ensemble Request Message (call it tMyAppRequest) based on data from the %request object, the %request.Headers List and the %request.Data(tParam, .tKey)=tValue,. You $order through the Parameters, and then the Keys and for each combination of Param and Key there will be a value even if it is null. Bear in mind that in a URL you can specify a parameter name more than once so it is best to build a $List tParamList=tParamList_$lb(tValue, tParam) and then insert the list into a property in your MyApplicationRequest.Parameters.Insert(tParamList) ten you move onto the next Parameter

Once your Request message is constructed you pass the request message to the Instantiated Business Service as follows:

Set tSC = tService.ProcessInput(.tMyApplicationRequest,.tMyApplicationResponse) and that will invoke the OnProcesInput(tRequest, .tResponse) method of your Business Service.

When it come s to CSP and REST I suspect that invoke similar logic to determine which Business Service in which Namespace the request will be directed to.

CSP REST calls do not use the REST Dispatcher. But you do Instantiate the correct Business Service Name though I see no reason why it can't but I would need to dig deep in the documentation to make sure.

Nigel