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Since PowerBuilder 2017 R2, we have a new HTTPClient object, which is a base object for sending HTTP requests and receiving HTTP responses from a resource identified by a URI. Compared to the Inet object, the HTTPClient object is easier to use and supports more methods (Get/Post/Put/Delete) and more SSL protocols (TLS 1.0, TLS 1.1, TLS 1.2, SSL 2.0, and SSL 3.0).

Among other things, the HTTPClient can be also used to consume SOAP Web services. This is particularly useful as the Web Service Proxy has many limitations and defects calling SOAP Web services such as not supporting TLS 1.2. This article is to show how you can use the new HTTPClient to call your existing SOAP Web services instead. 

Call SOAP Web services using Web Service Proxy

As a background story, let's revisit how PB consumes a SOAP Web service in the past. Firstly, you need to create a Web Service Proxy and then associate it with the pbsoapclient170.pbd or import pbsoapclient170.pbx.

Then in PB IDE, you instantiate the PB proxy with the SOAP Web service link and use the SOAPConnection object to call the associated Web service methods. 

Here is the sample code:

SoapConnection conn // Define SoapConnection

n_webservicesoap proxy_obj // Declare the proxy

long rVal

integer li_rtn

string str_endpoint

str_endpoint = "http://localhost/invoice/n_webservice.asmx?WSDL"

conn = create SoapConnection  //Instantiate connection

rVal = Conn.CreateInstance(proxy_obj, "n_webservicesoap", str_endpoint)

// Create proxy object

try

  li_rtn = proxy_obj.of_add(2)     //invoke Web service of_add method.

catch(SoapException e)

   messagebox("Error", "Cannot invoke Web service")

   // Error handling  

end try

destroy conn

Call SOAP Web services using HTTPClient

With the new HTTPClient object, we have a better option to call SOAP Web service.

1. Find the Correct SOAP Web service parameters

Open the SOAP Web service on IE as shown below. Copy the associated SOAP sample request. Refer to the highlighted content below. (If you don’t see this content, please contact your service provider to get such a sample request.)

 

Use a third party tool like Postman to verify what protocol and arguments you need to use to successfully call the Web service API.

Note: You need to replace the argument in the XML you copied in the previous step with the real argument to call the API. In this sample, we replace the word short (data type of the parameter ai_test for the of_add method) with the real argument(2).

2. Use the HTTPClient object to call the API.

After you verified successfully with Postman, apply the same protocol and arguments to HTTPClient object in your PB code. 

Here is the sample code:

httpClient lo_client

integer li_ret , i , li_StatusCode

String lo_xml_request

string ls_url

string ls_data

string ls_body

string ls_ret

 

ls_url ="http://localhost/invoice/n_webservice.asmx"

ls_body = ''+&

'

'xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:soap="http://schemas.xmlsoap.org/soap/envelope/">'+&

'  '+&

'    '+&

'      2'+&

'    '+&

'  '+&

'

'

lo_client = Create httpClient

lo_client.SetRequestHeader("Content-Type", "text/xml")

lo_client.sendrequest('POST',ls_url,ls_body)

 

li_StatusCode = lo_client.GetResponseStatusCode()

ls_ret = lo_client.GetResponseStatusText( )

li_ret = lo_client.getresponsebody(  ls_data)

destroy lo_clien

The new approach for calling SOAP Web services is clean and simple, and it gives you more flexibility than the previous approach. We hope that you will find this article useful in your implementation of the consumption of SOAP Web services in your applications. 

 

Comments (18)

  1. Miguel Leeuwe

Hi Tom,

Thank you for sharing this knowledge but I have some questions:

Could you please explain how to "Use a third party tool like Postman to verify what protocol and arguments you need to use to successfully call the Web service API."?
I've downloaded PostMan but I don't see what to do with it to "get the protocol and arguments". Then I neither see where to put the "protol" once I would have gotten it.

Also: Is this faster then using the traditional way with Soap? Sorry for my ignorance and thank you.

  Comment was last edited about 6 months ago by Miguel Leeuwe Miguel Leeuwe
  1. Tom Jiang    Miguel Leeuwe

Hi Miguel,

We mentioned Postman mainly for you to test and verify if you can directly call the API from your service provider successfully on your machine.

It would also help you to understand how to set up the parameters for HTTPClient. If your service provider has already provided you a complete API documentation, you can ignore this part.

Regrading how to use Postman, we suggest that you do a Google search or refer to the tutorial on Postman’s official site.

BTW, HTTPClient object is for sure much better than the traditional way with SOAP both in terms of flexibility and efficiency. You can give it a try.

Regards,

Tom Jiang

 
  1. Miguel Leeuwe    Tom Jiang

Thank you.
regards,
Miguel

 
  1. Sergey Khudyakov

Hi Tom

I was trying to migrate Soap client with .NET assembly from PowerBuilder 11.5 where it was running perfectly.
In PB 2017 R3 Web Service proxy was deployed succesfully, but when I call web service method, raised SoapException:
The SoapClient doesn't support .NET proxy

Are you still supporting .NET assembly for web services?

Sergey

 
  1. Tom Jiang    Sergey Khudyakov

1. Please refer to PB help or the following link. SOAPClient is obsoleted, which means it is no longer eligible for technical support and will not be enhanced.
https://www.appeon.com/support/documents/appeon_online_help/pb2017r3/application_techniques/ch35s03.html#d0e23597

2. About supporting .NET assembly for web services
PB 2017 is inherited from PB 12.6. No restrictions or changes are made on this feature. In other words, if it works in PB 12.6, it should still work in PB 2017. But if you do have problem using it, we suggest that you use HTTPClient to rewrite your function.

 
  1. Sergey Khudyakov    Tom Jiang

Thank you for reply Tom.

Yes, I already tested new HTTPClient and even make nice visual interface to work with it.

And yes, it's good to have full control for making http request and parsing http response.

(Sometime when I was stacked with old SoapClient with complex Web Servicis, I was thinking that will be nice to have naked HttpClient and here is it ))

From the other side you may need more coding and may be use PBDOM for parsing complex response body.

 
  1. Topher Chen    Sergey Khudyakov

Hi Sergey,

Are you able to use HttpClient in .Net Assembly?
We are facing an issue using webservice proxy to call WebService on .Net Assembly, but there is a performance issue, it takes around 1.5 second to make a call even it is just a 'Helleworld' like program, so we want to use HttpClient which is much faster, but .Net assembly doesn't support it.

 
  1. Roland Smith

How do you create the web service? You can't call one until it exists.

 
  1. Tom Jiang    Roland Smith

Hi Roland,

The intention of this article is to provide a solution for consuming existing SOAP web services especially when it requires the TLS1.2 protocol.

If you don't have the web service, We highly recommend that you try our coming C# Web API solution. Please refer to the section on SnapDevelop on this page https://www.appeon.com/documents. There are step by step tutorials teaching you how to create and consume web APIs.

 
  1. Sverre Tvedt

I am planning to migrate all our web service client projects to the new httpclient object from the traditional .NET/EasySoap proxy way. The main reason is the death knell tolled for TLS 1.0, and the somewhat slow performance of the .NET projects.
However, one of the nice features of those traditional projects was the ability to generate all the data contract nvos needed for complex web services. So far, I like to use the .NET project for generating these nvos from the wsdl, later supplying them with my own xml serializer/de-serializer methods.

I hope this functionality for generating nvo's will be kept in some way?

  Comment was last edited about 4 months ago by Sverre Tvedt Sverre Tvedt
  1. Tom Jiang    Sverre Tvedt

Hi Sverre, the functionality for generating NVOs will still be kept for the traditional projects. The new HTTPClient object is just a general purpose tool to handle HTTP reuqests. There are also new objects like RESTClient, JSONParser tailored to RESTful web services. But at this moment, there is no plan for enhancing the old proxy project for handling SOAP web services.

 
  1. Richard Keller    Sverre Tvedt

You can force TLS 1.2 via the registry with the .Net/East Soap Proxy. This is a fallacy.

https://support.microsoft.com/en-us/help/3140245/update-to-enable-tls-1-1-and-tls-1-2-as-default-secure-protocols-in-wi

 
  1. Armeen Mazda    Richard Keller

Sure but the .NET/EasySoap is not supported by Appeon. This article outlines a supported approach to call legacy SOAP Web services.

 
  1. Martijn van Dongen

Can I set the HTTP header using the HTTPClient object approach ?

 
  1. PRATHEEP JOHN

Till now we were calling web service by web proxy. Now I was trying to call by HTTPClient Object.
But the web service is returning a structure. But by HTTP client we are only getting a string, so any way we can resolve it?

 
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