wcf - Should I avoid message inheritance in WCF?

Question

Generally, I try and avoid using inheritance in WCF contracts, preferring composition.

But in the following situation...

• I have a service operation that can result in one of two things: ResultA and ResultB.
• There is a boolean/enum in the response message to report this outcome.
• There are a number of other properties in the response message. Some of these are only relevant in the event of ResultA and some are only relevant in the event of ResultB.

I see my options as being:

1. Have a single response message contract that contains everything and when properties are not relevant, they are left as null. The client then has to look at the bool/enum to see if its ResultA or ResultB and ignore properties accordingly.
2. Have 2 response messages contracts, both inheriting from a shared base. One representing ResultA and its relevant properties and one representing ResultB and its relevant properties.

I much prefer option 2 for a number of reasons, but it breaks the composition over inheritance rule.

What do people think?

Answer 1

我的直觉是“重新设计你的界面”。具有可疑返回类型的方法通常不是良好设计的标志。这会导致该方法的每个调用者出现大量不必要且容易出错的逻辑。

所以我建议“秘密选项 3”：将接口重构为两个单独的方法。

Answer 2

更喜欢组合而不是继承！=永远不要使用继承:-)

Answer 3

所有规则都是用来打破的。如果您正在重用对象并且系统允许您使用继承......为什么不使用它呢？正如Phil Haack所说的那样……为自己考虑。

用一套人为的规则来限制自己是让你工作变得更加困难的好方法。我们可以使用继承是有原因的，我说这就是其中之一。

比继承更喜欢组合（史蒂夫·罗） 这是另一个角度。但是，如果您阅读它，他说的是功能的重用，而不是数据的重用。