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I didn’t know you could do that!

By Richard Morris, Posted on March 23, 2017 at 2:34 pm

Working with the many customers we have is a great opportunity to advance the software we write. Some time ago I blogged about Symphony Bridge – a server based utility that allows you to expose Synergy data and logic through Symphony Harmony using an SQL-like syntax. In essence you can write queries on the client like “select * from part” and the bridge server will return a collection of part objects that are based on a structure you have created in your repository. You can then bind these to grids or input controls on you windows or mobile applications or display them in web pages. In fact you can use the data in any Synergy .Net or non-Synergy application.

Another aspect of Symphony Harmony/Symphony Bridge is the ability to call a remote procedure using the syntax “exec @MyNameSpace.MyClass.MyMethod”. You can pass in arguments and again a data object or a collection of data objects are returned.

During a recent visit with one of our customers who is currently utilizing symphony Harmony and Symphony Bridge to provide third-party access to their systems to allow enquiries on orders, etc. I was asked about “providing the ability to return a standard object that contains the call status AND the response data”. Simple, no problem: Create an RPS structure that defines your response details – call status, error codes, and error message for example. Code generate the required data object and then customize it by exposing a collection of <DataObjectBase> (the base class of all data objects!) As I said – simple.

But the customer was not overly impressed – and they had an idea! Oh dear me thinks – these are seasoned C# developers and I’m not convinced I’ll be able to implement their ideas in Synergy .Net! But how wrong I was…. and without any changes to the Symphony Framework. The basic requirement is to have a “response” class that they can extend with any serializable “type” – be that a single instance or a collection of “type” – without any restrictions.

The starting point was the same – create the required response structure in the repository and code-generate the “response” class. This is the resulting class definition;

public partial class Server_response_Data extends Symphony.Conductor.Model.DataObjectBase

The code generation process creates all the required properties and the logic to serialize the data into JSON or BSON.

The next step was to create a second class with the same name as the response class but this time it will accept a generic – generics are quite cool and allow you to defer the specification of a type until that type is instantiated. So our generic response class definition looks like this;

public class Server_response_Data<T(new)> extends Server_response_Data

By extending the base code-generated class we get all the required Symphony capabilities. The “T” denotes the generic “type”. The (new) ensures that any type you provide must have a parameter-less constructor which ensures that this class can creates an instance of it. We can expose the property so it’s serializable;

{JsonProperty}
public property Result, T
       method get
       endmethod
       method set
       endmethod
endproperty

And in the constructor we can ensure there is an instance (to prevent null object exceptions);

public method Server_response_Data
       endparams
proc
       Result = new T()
endmethod

And that is about it. You can then write your server methods to create an instance of your response class, populate the generic “response.Result” with the required “type” and set the response properties accordingly. For example;

data response = new Server_response_Data<Part_Data>()

Will create a response class with the “Result” as a type of Part_Data data object. If you need to return a collection of Part_Data objects;

data response = new Server_response_Data<List<Part_Data>>()

It’s really as easy as that. On the client you simply make the remote EXEC call through Symphony Harmony;

result = DataExecute.RunDataExecute(connector,
       &      "exec @MyNameSpace.MyClass.MyMethod",
       &      new Server_response_Data<List<Part_Data>>()).Result

You can also await the call on a separate thread.

Big shout-out to Gareth for the idea and his persistence to make me get it working!

I’ll be using these techniques in my DevPartner 2017 post conference workshop as we build a mobile app from start to finish using Symphony Harmony/Symphony Bridge to access remote data and logic.


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