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With the creation of REST-based Web services and their ability to store and retrieve data comes the question of how to store data. In a SQL database, you can use the SQL SELECT to query the database and generate a result set. That’s what you’re doing for 90% or so of the database operations and the Web.
However, to be able to query a database or Web site, you have to have data to query or browse. This raises the question of how to put the data into the Web. In the case of the database, the answer is easy: you execute SQL statements, and data is stored in the database. However, it is possible to use C and some file operations to add entries into the database. Well, at least that is theoretically possible. The problem is that companies such as Oracle, Microsoft, and IBM aren’t going to tell you how their files are structured. That lack of documentation is the decision maker of whether you use REST to store data, or whether you use background processes. The database vendors aren’t going to allow you to add data to their database using C file operations, because you would corrupt the database. Whenever you execute a SQL insert statement, a whole host of things happen (such as indexing and optimization) that wouldn’t occur if you accessed the database directly. Let’s go back to the original question: Should REST-based Web services be closed access? The answer is yes, whenever possible. For example, it might not be possible when you’re dealing with legacy applications such as the blogging application.
You want a REST-based Web service to have closed access, because it is your nextgeneration data source. Relational databases are wonderful persistence tools, but they have their limits, especially in the context of Internet-based applications. You could use objectoriented databases, but they haven’t caught on for one reason or another the reality is that most data is stored in relational databases. With REST-based Web services, you want to encapsulate the logic on the server and expose a set of URLs that represent Web service operations.
Article Summary This article illustrated how to build universal Web services using REST-based techniques. Remember the following points:
• You should treat Web services as components and only implement the functionality necessary.
• As the example illustrates, you don’t need to componentize the Web service. That doesn’t mean that componentization is not necessary, nor does it mean that you should ignore good object-oriented design principles. It does mean that you don’t always need to componentize, and you should consider the Web service boundary as part of your componentization.
• Only create code components when it makes sense. The aim is to componentize your application using Web services.
• Your Web service will be a success based on its interface and the usability of the interface, not on the code behind the interface. For example, if you need a fast response time, write code that is fast, even if that means using arrays instead of linked lists and so on.
• Using classes instead of components doesn’t mean that you cannot configure the behavior of your Web service. For example, you don’t have to hard-code the URLs used to define the Web service. Configurability and componentization are two orthogonal issues.
• When defining the Web service, focus on the URLs and the data that the URLs accept and generate.
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