218

Developing Client Applications to Use a Web Service

Table 5.1

Client Communication Modes (

continued

)

Client 

Considerations

Stub

Dynamic Proxy

DII

Supports one way 

No

No

Yes

communication mode

Supports the ability 

No. Developer must 

No. Developer 

Yes. However, returns 

to dynamically spec 

program against a 

must program 

Java objects which the 

ify JAX RPC value 

service endpoint 

against a service 

developer needs to cast 

types at runtime

interface.

endpoint interface.

to application specific 

objects as necessary.

Supported in J2ME 

Yes

No

No

platform

Supported in J2SE 

Yes

Yes

Yes

and J2EE platforms

Requires WSDL

No. A service end 

No. A partial 

No. Calls may be used 

point interface may 

WSDL (one with 

when partial WSDL or 

generate a stub class 

the service port ele 

no WSDL is specified. 

along with informa 

ment undefined) 

Use of methods other 

tion concerning the 

may be used.

than the 

createCall

protocol binding.

method on the 

Call

interface may result in 

unexpected behavior in 

such cases.

Choose the communication mode for your client application after considering the

following:

E

J2EE clients should use stubs. Stubs are easiest for developers to use. Keep in 

mind, however, that with stubs you might lose some portability across JAX 

RPC implementations. 

E

J2EE components acting as clients should use dynamic proxies when portabil 

ity is a requirement. Since dynamic proxies do not require a JAX RPC map 

ping file, some ambiguity may occur, and this may result in unexpected 

behavior when calling a service.

E

DII is the most difficult to use of the three approaches. Only consider using DII 

if you need the runtime ability to look up operations.

E

All J2SE and J2ME clients should use stubs if at all possible.