Development Update September 2008 - 4GL Web Service Client

Hydra4GL Version 4.31 and Lycia will support 4GL Web Service Functionalilty in the GUI clients.

4GL Web Service Client

Provides a means of invoking Web Services from 4GL application logic.

Features:

• Supports both RPC/Encoding and Document/Literal binding styles
• Support for SOAP 1.1 and SOAP 1.2
• Support for Fire & Forget and Send & Receive transaction models
• Support for MTOM and SwA

4GL Web Service Client

Decomposing WSDL

• WSDL2FGL tool decomposes the WSDL from a service into 2 descriptions
• A meta description used by the 4GL Web Service client.
• A 4GL function stub that provides the necessary routines to invoke the methods details in the WSDL.

4GL Service Description

#-----------------------------------------------------------
# SERVICE NAME :  hello
#-----------------------------------------------------------
PORT NAME :  helloSOAP11port_http
PORT URL :  http://localhost:9080/axis2/services/hello
SOAP VERSION:  SOAP1.1
BINDING STYLE : document/literal
METHODS : 
METHOD NAME : f1
INPUT PARAMETERS : 
   param0 INTEGER
RETURN VALUES : 
   return VARCHAR
#-----------------------------------------------------------
PORT NAME :  helloSOAP12port_http
PORT URL :  http://localhost:9080/axis2/services/hello
SOAP VERSION:  SOAP1.2
BINDING STYLE : document/literal
METHODS : 
METHOD NAME : f1
INPUT PARAMETERS : 
   param0 INTEGER
RETURN VALUES : 
   return VARCHAR

Internal ‘meta’ description

• Stored as XML in $QUERIXDIR/meta/wsclient
• One meta file is created for each service

For each Service the metadata describes the available ports, operations and the bindings to those operations

Client Perception of Web Services

Invoking Web Services from 4GL

Two sets of function calls allow the user to access web services from 4GL

• fgl_ws_call()
  A set of request building functions
  
• fgl_ws_create()
• fgl_ws_setparameters()
• fgl_ws_execute()
• fgl_ws_getdata()
• fgl_ws_close
• fgl_ws_error()

fgl_ws_call()

An atomic invokation of a Web Service. Best suited to Fire & Forget methods, but also supports Send & Receive
Always returns the same number of parameters as the service being invoked
If any expected input parameters are not supplied, the values are substituted with NULL equivalents

fgl_ws_call()

Input parameters consist of Service Name, Port Name and Operation Name. Any input variables are supplied in addition to these

CALL fgl_ws_call(“hello”, # service
 	“helloSOAP11port_http”, # port
	“f1”,  # operation
 	3)  # optional parameters

Request Building Functions

• Suited to Send & Receive operations
• Able to provide error diagnostics on failed execution

Request Lifecycle

• The user creates a client instance using fgl_ws_create().
• Input data is bound to the instance using fgl_ws_setparameters()
• The client instance is invoked using fgl_ws_execute()
• 4GL data is retrieved from the instance using fgl_ws_getdata()
• The client instance is terminated using fgl_ws_close()
• If the execution call fails, diagnostics can be received using fgl_ws_error()

Request Example

CALL fgl_ws_create(handle, p_service, p_port, operation)
CALL fgl_ws_setparameters(handle, my_short)

IF NOT fgl_ws_execute(handle) THEN
  DISPLAY fgl_ws_error(handle)  
END IF

CALL fgl_ws_getdata(handle)
  RETURNING my_record.*

CALL fgl_ws_close(handle)