74

Designing a Service's Interaction Layer

  Java primitive types 

boolean

, 

byte

, 

short

, 

int

, 

long

, 

float

, and 

double

, along 

with their corresponding wrapper Java classes

  Standard Java classes: 

String

, 

Date

, 

Calendar

, 

BigInteger

, 

BigDecimal

, 

QName

, and 

URI 

  Java arrays with JAX RPC supported Java types as members

  JAX RPC value types user defined Java classes, including classes with 

JavaBeans

TM

 component like properties

E

When designing parameters for method calls in a Web service interface, 

choose parameters that have standard type mappings. (See Figure 3.3.) Always 

keep in mind that the portability and interoperability of your service is reduced 

when you use parameter types that by default are not supported. 

As Figure 3.3 shows, parameters that have standard type mappings are bound

implicitly. However, the developer must do more work when using parameters

that do not have standard type mappings. See  Handling Nonstandard Type

Parameters  on page 76 for more details on using nonstandard Java types and pos 

sible side effects of such use.

Here are some additional helpful points to consider when you use Java objects

with standard type mappings as parameters.

1. Many applications and services need to pass lists of objects. However, utilities 

for handling lists, such as 

ArrayList

 and 

Collection

, to name a few, are not 

supported standard types. Instead, Java arrays provide equivalent functional 

ity, and have a standard mapping provided by the platform.

2. JAX RPC value types are user defined Java classes with some restrictions.

They have constructors and may have fields that are public, private, protected,

static, or transient. JAX RPC value types may also have methods, including set

and get methods for setting and getting Java class fields.

However, when mapping JAX RPC value types to and from XML, there is no 

standard way to retain the order of the parameters to the constructors and other 

methods. Hence, avoid setting the JAX RPC value type fields through the con 

structor. Using the get and set methods to retrieve or set value type fields 

avoids this mapping problem and ensures portability and interoperability.

3. The J2EE platform supports nested JAX RPC value types; that is, JAX RPC

value types that reference other JAX RPC value types within themselves. For