Sự khác biệt là các tin nhắn được ràng buộc với các hoạt động phong phú và phức tạp, trong khi phương pháp RPC-phong cách đơn giản là trả về một kết quả riêng biệt là tương quan trực tiếp đến một tập cụ thể của thông số đầu vào. Ví dụ, một phương pháp định hướng thông điệp Web sẽ chấp nhận một biểu tượng mã cổ phiếu | CHAPTER 3 Design Patterns for Building Message-Oriented Web Services In an SOA the purpose of Web services is to exchange and process XML messages not simply to act as hosts for remote procedure call RPC style methods. The difference is that messages are bound to rich and complex operations whereas RPC-style methods simply return a discrete result that is directly correlated to a specific set of input parameters. For example a message-oriented Web method will accept a stock ticker symbol and return a detailed stock quote in response. In contrast an RPC-style Web method will return a simple output value. Unfortunately development tools such as Visual Studio place a method-centric focus on Web services that causes you to lose sight of the bigger design picture and to take the underlying infrastructure for granted. It is very easy to build a Web service by creating an .asmx file and then throwing together several loosely related RPC-style Web method implementations. However this is the wrong design approach because such a Web service fails to provide an integrated set of message endpoints. In simpler terms the Web service fails to provide a service. The right design approach is always to think in terms of operations and XML messages and to consider how the Web service methods work together to provide a service. This chapter begins with a challenge for you to set aside what you have learned about Web services development until now and to open your mind to a different design approach one that is based on integrated XML messages not on RPC-style methods. How to Build a Message-Oriented Web Service There are six steps involved in building a message-oriented Web service which is simply a Web service that exchanges XML schema-based input and output messages rather than simple parameter-oriented values. The steps are described in the following sections. Step 1 Design the Messages and the Data Types Conceptually design what the messages and data types will look like. UML .
