Uniphar.Sap.Odata.Client 1.0.6

sap-odata-client

NuGet package repository for Sap OData Client connection

Purpose

This library is for making calls to SAP (running in AZ). Calls to SAP require a base url. Full path will be decorated with the namespace of the service we call.

Calls to the SAP instance requires authentication with Basic auth - (username and password). These are stored in a secret storage and you do not need to define these. The secret storage can be AZ Keyvault, AWS Secrets Manager or others. Any token expiry is automatically handled by the SAP client and is not something to be concerned with either.

Custom Events

The library also publishes some custom telemetry events. This is because there has been several issues with the SAP Rise environments. We publich the following events

Setup your project to use SapClient package

When using this NuGet package you need to setup a few things in your project

appsettings.json

Add this to appsettings.json

  "SapClientOptions": {
    "BaseUrl": "https://<sap-baseurl>",
    "PooledConnectionLifetime": "00:00:15",
    "UseHttpClientHandler": false,
     "FetchTokenStatusCodeTriggers": [
        401,
        403
        ]
  }

NOTE: The baseUrl value is currently IP based, but should be DNS based. UseHttpClientHandler tells whether to use HttpClientHandler (true) when instantiating HttpClient or SocketsHttpHandler (false), for which we use the PooledConnectionLifetime. FetchTokenStatusCodeTriggers is a list of HttpCodes we test against to trigger fetching a new token. Normally it should just be 403, but we have to apply a hack to support 401 as well.

Program.cs

Add the following to Program.cs

• Add this to bind the above configuration section to class SapClientOptions. That will ensure we can DI it into the SapClient class.

builder.Services.Configure<SapClientOptions>(
    builder.Configuration.GetSection(nameof(SapClientOptions)));

• Register a singleton instance of HttpClient, as SapClient makes calls to SAP RISE over HTTP.

    //  Register Http client
    builder.Services.AddSingleton(new HttpClient
        (
        bool.Parse(builder.Configuration["SapClientOptions:UseHttpClientHandler"]) ?
        new HttpClientHandler
        {
            ServerCertificateCustomValidationCallback = HttpClientHandler.DangerousAcceptAnyServerCertificateValidator
        }
        : new SocketsHttpHandler
        {
            PooledConnectionLifetime = TimeSpan.Parse(builder.Configuration["SapClientOptions:PooledConnectionLifetime"])
        }
        )
    {
        BaseAddress = new Uri(builder.Configuration["SapClientOptions:BaseUrl"])
    });

    //  Register SAP client
    builder.Services.AddSingleton<ISapClient, SapClient>();

When running locally

Add this in appsettings.Development.json. That means we bypass any Cert logic when running locally (see above in registering the Http client)

  "SapClientOptions": {
    "UseHttpClientHandler": true
  }

Using SapClient library

We have a couple of predefined (and custom) JsonSerialisers we need to use when calling SAP. This is handled by class SapJsonSerializer. It exposes a static method:

  public static JsonSerializerOptions GetJsonSerializerOptions()
  {      
      //  preliminary code logic        
      jsonSerializerOptions.Converters.Add(new SapDateTimeConverter());
      jsonSerializerOptions.Converters.Add(new SapDateTimeOffsetConverter());
      jsonSerializerOptions.Converters.Add(new SapDecimalConverter());

      return jsonSerializerOptions;
  }

The SAP client package exposes two methods

Task<ContentResult> GetAsync<T>(string path, CancellationToken cancellationToken)
Task<ContentResult> PostAsync<T>(string path, T message, CancellationToken cancellationToken)

Both methods return a ContentResult, which means we can handle based on the Http status code in the response.

Example usage:

        public async Task<ActionResult<SalesOrderResponse>> CreateToDoList([FromBody] CreateToDoList createToDoList, CancellationToken cancellationToken)
        {
            //  Call SAP Client to get Serializer Options  
            var serializerOptions = SapJsonSerializer.GetJsonSerializerOptions();
            
            //  Make call to SAP Client  POST method
            var createdTodoListContentResult = await _sapClient.PostAsync("TO_DO_LIST_API", createToDoList.MapToSapToDoListRequest(), cancellationToken);

            switch(createdTodoListContentResult.StatusCode)
            {
                case 201:
                    var createdSapTodoListResult = JsonSerializer.Deserialize<OData<ToDoList>>(createdTodoListContentResult.Content!, serializerOptions);

                    //  Make call to SAP Client GET method                        
                    var sapToDoListWithItems = await _sapClient.GetAsync<OData<ToDoList>>(
                        $"TO_DO_LIST_API/TO_DO_LIST_ITEM('{createdSapTodoListResult!.Data!.Id}')?$expand=to_Item", cancellationToken);
                    
                    var sapToDoList = JsonSerializer.Deserialize<OData<ToDoList>>(sapToDoListWithItems.Content!, serializerOptions);
                    var newSapToDoList = sapToDoList!.Data!.MapToSapToDoListResponse();

                    return CreatedAtAction(nameof(CreateToDoList), new { id = newSalesOrder.Id }, newSalesOrder);
                    
                case 400:
                    var sapErrorResponse = JsonSerializer.Deserialize<SapErrorResponse>(createdTodoListContentResult.Content!, options);
                    return BadRequest(sapErrorResponse!.MapToProblemDetails());
                default:
                    return new StatusCodeResult((int)createdTodoListContentResult.StatusCode!);
            }
        }