SCA for PHP generates WSDL for components which contain an
@binding.soap annotation after the @service annotation. To
generate WSDL, the SCA runtime reflects on the component and
examines the @param and @return annotations for each public
method, as well as any @types annotations within the component. The
information from the @param and @return annotations is used to
build the <types> section of the WSDL. Any @types
annotations which specify a separate schema file will result in an
<import> element for that schema within the WSDL.
Location attribute of the <service> element
At the bottom of the WSDL is the <service> element
which uses the location attribute to identify the URL of the
service. For example this might look as follows:
Example #1 location attribute
<service name="ConvertedStockQuote"
...
location="http://localhost/ConvertedStockQuote/ConvertedStockQuote.php"/>
Note that this location is relative to the document root of
the web server, and cannot be worked out in advance. It can only be
worked out once the component is in its proper place under a running
web server, when the hostname and port can be known and placed in the
WSDL. Detail from the URL that requests the WSDL is used, so for
example if the WSDL is generated in response to a request to
http://www.example.com:1111/ConvertedStockQuote/ConvertedStockQuote.php?wsdl,
a location of
http://www.example.com:1111/ConvertedStockQuote/ConvertedStockQuote.php
is what will be inserted into the location attribute in the WSDL.
Document/literal wrapped WSDL and positional
parameters
SCA for PHP generates WSDL in the document/literal wrapped
style. This style encloses the parameters and return types of a
method in 'wrappers' which are named after the corresponding
method. The <types> element at the top of the WSDL defines
each of these wrappers. If we consider the
getQuote() method of the
ConvertedStockQuote example:
Example #2 method with two arguments
<?php
/**
* Get a stock quote for a given ticker symbol in a given currency.
*
* @param string $ticker The ticker symbol.
* @param string $currency What currency to convert the value to.
* @return float The stock value is the target currency.
*/
function getQuote($ticker, $currency)
{
$quote = $this->stock_quote->getQuote($ticker);
$rate = $this->exchange_rate->getRate($currency);
return $rate * $quote;
}
?>
The WSDL generated to define this method will name both the
method and the parameters, and give an XML schema type for the
parameters. The types section of the WSDL looks like this:
Example #3 types section illustrating named parameters
<types>
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema"
targetNamespace="http://ConvertedStockQuote">
<xs:element name="getQuote">
<xs:complexType>
<xs:sequence>
<xs:element name="ticker" type="xs:string"/>
<xs:element name="currency" type="xs:string"/>
</xs:sequence>
</xs:complexType>
</xs:element>
<xs:element name="getQuoteResponse">
<xs:complexType>
<xs:sequence>
<xs:element name="getQuoteReturn" type="xs:float"/>
</xs:sequence>
</xs:complexType>
</xs:element>
</xs:schema>
</types>
The SCA run-time has special processing to handle how
positional parameter lists in the interface are converted to XML
containing named parameters in the soap request, and then back to
positional parameter lists again. To see why this matters,
consider how a PHP script which used a different interface to make a
SOAP call would need to construct the parameter list. A PHP script
using the PHP SoapClient, for example, would need to pass the
SoapClient a single parameter giving the values for "ticker" and
"currency", perhaps as an associative array. To insist that SCA
components construct parameter lists to make Web service calls in
this way would be to make local and remote calls look different, so a
different approach is needed.
When SCA generates WSDL for an SCA component it includes a
comment in the WSDL which marks that WSDL as being the interface for
an SCA component. In this case, when one SCA component calls
another through a Web service, the SCA runtime on the calling end
takes the positional parameter list from the call and assigns the
values one by one to the named elements in the soap message. For
example a call to the
getQuote() method defined above that
passes the values 'IBM' and 'USD' and looks like this:
$quote = $remote_service->getQuote('IBM','USD');
will result in a soap message containing the
following:
<getQuote>
<ticker>IBM</ticker>
<currency>USD</currency>
</getQuote>
On the service-providing end, the SCA run-time takes the
parameters one by one from the soap message and forms a positional
parameter list from them, re-forming the argument list
('IBM','USD').
Caution
At both ends the SCA runtime relies on the order in which the
parameters appear in the soap message being the same as that in the
target method's parameter list. This is ultimately determined
by the order of the @param annotations: this determines the order
in which the parameters appear in the WSDL and thereby the order in
which they appear in the soap message. Therefore it is essential
that the order of the @param annotations matches that of the
parameters in the method's parameter list.
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