Hi Sudheer,
Yes, we can use Web services created in .Net, Java, PHP etc.
To consume these Web Services we have to create a Consumer Proxy in SAP ECC. Following are the steps:
1) In transaction SE80, you have to create Consumer Proxy from Enterprise Services which you will find after clicking the 'Edit Object' button.
2) It will open a dialog box in which you have to select the Enterprise Services tab. In this tab there is a Client Proxy radiobutton, select it and give the desired name. Please make sure that you start it with 'Z' or 'Y'.
3) After clicking create, it will open a wizard for creating the client proxy. Use the 'external WSDL' radio button if you want to access a web service created in the external system. Provide the URL for Web service in the next screen.
4) Now, go to the transaction SOAMANAGER. Here you will have to configure the logical port for the client proxy. You will have to provide the hostname/ip and the port on which the Web service is located. These details will be available in the URL of the Web service.
5) Now you can write a simple ABAP code to verify if the you are able to get the desired result from the Web service.
Regards.
Saurabh