Where can I find more information about Web services?
Quite a number of good books have been published recently on the subject of Web services, as the topic grows in popularity every day. An excellent book on the topic is Microsoft .NET Web Services by Robert Tabor, from Sams Publishing.
Can any object be sent over Web services?
Yes, but not necessarily automatically. To transmit custom classes or data types, you will need to tell the framework how to convert the object to XML. This is referred to as XML serialization. The Microsoft .NET Framework automatically serializes almost all simple data types. For more information, see XML serialization in the Microsoft .NET Framework SDK documentation.
Are Web services reliable?
The answer is "it depends." Web services use XML and HTTP, both of which are battle- tested and proven protocols themselves. From this perspective, you can rely on the fact that you'll have few problems with Web services themselves , as long as they are accessible.
However, Web services are only as reliable as their weakest link. If you are invoking a Web service located on a server in your company's domain, it is likely to be very reliable ”and if the Web service does go down, most likely your organization has an IT staff you can notify. However, consider the number of times transient Internet conditions have prevented you from accessing a favorite Web site. There are many points of failure between any two machines on the Internet that are entirely out of your control. Therefore, any Web services provided by hosts on the Internet are by their very nature unreliable and not fit for use in mission-critical applications.
Remember that when the Nimda virus reached its peak number of infections, the amount of additional Internet traffic generated by the virus caused sites to be unavailable or slow to load for several days. This poor performance would be reflected directly by any application making use of a remote Web service.