Creating a WCF Service in Visual C#

Generation ANSI/AIM Code 39 in Visual C# Creating a WCF Service

You can set up the profile once, and then reuse it every time you have to republish the application Pretty slick

All there is left to do is use it As one would expect, setting up a service reference for a WCF service is a lot like setting up a reference for an ASMX service You still right-click and select Add Service Reference, you still get the dialog box shown in Figure 3-9, and you still can reference the service easily in your code Two things to remember: The file extension you are looking for is svc The binding you set up is abstracted away from you The filename thing is workable, but the binding is important Keep in mind that the selecting of a binding is invisible to the developer, but it has a significant impact on functionality and especially performance The decision of which to use is not to be made lightly; it should be done only after much research and needs analysis

Understanding the principles of ReST Implementing ReST services using WCF Consuming ReST services

hapter 3 includes a sidebar, Using Different Endpoints, that has a big list of binding formats you can use with WCF I point out that for most applications, you use SOAP, or binary That s not necessarily accurate Another binding is pretty popular it is the binding that your Web browser uses to get pages from Web servers It is called ReST, and it stands for Representational State Transfer In this chapter, I introduce you to ReST and guide you through its advantages and drawbacks

ReST is basically the use of the traditional GET and POST patterns the old folks will remember from CGI For you young pups, it is the basic format of Web requests For instance, when you click on a link that looks like this:

you are using ReST Remember, we aren t talking about an implementation here We are talking about a remote procedure call mechanism It is just a way to get parameters for a query to a remote machine and to get data back We also aren t talking about a protocol, like SOAP is ReST is an architecture It has guidelines, not rules A ReST interface has four goals They are

Scalability of component interactions Generality of interfaces Independent deployment of components Intermediary components to reduce latency, enforce security, and encapsulate legacy systems Use of ReST with WCF meets most but not all of those goals Let s take a quick ride over the details of the implementation of ReST in WCF, and you can make your own call

There are four guiding principles to ReST According to the standard, all ReSTful interfaces must provide interfaces that adhere to these principles In the real world, compliance is up for discussion Here are the principles: Identification of resources: Individual resources (like a data item, for instance) are identified in requests (for example, using URIs in Webbased ReST systems) The resources themselves are conceptually separate from the representations that are returned to the client For example, the server does not send its database, but rather, perhaps, some HTML, XML, or JSON that represents some database records expressed, for instance, in French and encoded in UTF-8, depending on the details of the request and the server implementation Manipulation of resources through these representations: When a client holds a representation of a resource, including any metadata attached, it has enough information to modify or delete the resource on the server, provided it has permission to do so Self-descriptive messages: Each message includes enough information to describe how to process the message (for example, which parser to invoke) An example of this is the use of Internet media types, previously known as MIME types From the media type alone, the client must know how to process its contents If it needs to look inside the message s contents in order to understand it, the message is not self-descriptive For example, merely using the application/xml media type is not sufficient for knowing what to do with its contents, unless code-download is used Hypermedia as the engine of application state: If it is likely that the client will want to access related resources, these should be identified in the representation returned (for example, by providing their URIs in sufficient context, such as hypertext links) This creates an environment where the software system consuming the service has more than normal knowledge of the way the data is stored