First Class Headers - Proposed Resolution for LC76d

LC76d -  <http://www.w3.org/2002/ws/desc/4/lc-issues/#LC76d>
http://www.w3.org/2002/ws/desc/4/lc-issues/#LC76d

#1: At the Melbourne F2F, I observed a simple majority to explore header
proposals that are independent of the Features and Properties framework.
This draft is one such mechanism. It accommodates SOAP 1.1, SOAP 1.2 and
HTTP Bindings. AFAIK, this draft resolves all the sub issues raised by
Jeffrey Schlimmer in LC76d.

The number two driving force behind this proposal is the desire for
simplicity. I bet the user community will enthusiastically receive a product
that simplifies their work and reduces their time to market.

This is the first draft. I made it as brief as possible. If there is
sufficient interest, I will continue to produce newer versions that will
accommodate your requirements and issues. At the least, this proposal will
provide sufficient information to the WSDL Working Group to make an informed
decision.

Comments, suggestions, corrections, thumbs up, thumbs down .. are greatly
appreciated.

Regards,

Asir S Vedamuthu
asirv at webmethods dot com
 <http://www.webmethods.com/> http://www.webmethods.com/


  _____  


First Class Headers - Proposed Resolution for LC76d


Lets begin with a simple example. The following example shows the WSDL
definition of a simple service providing stock quotes. This service supports
a single operation called GetLastTradePrice, which is deployed using the
SOAP 1.2 protocol over HTTP. I added 3 statements to turn on WS-Security
header support. Again, just 3 statements - import schema statement, header
in input message reference component and header in output message reference
component.

<?xml version="1.0"?>

<wsdl:definitions name="StockQuote"
xmlns:wsdl="http://www.w3.org/@@@@/@@/wsdl"

  targetNamespace="http://example.com/stockquote"

  xmlns:tns="http://example.com/stockquote"

  xmlns:wsoap="http://www.w3.org/@@@@/@@/wsdl/soap"

 
xmlns:wsse="http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-wssecuri
ty-secext-1.0.xsd">

    

  <xs:import

 
namespace="http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-wssecurit
y-secext-1.0.xsd"

 
schemaLocation="http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-wsse
curity-secext-1.0.xsd"/>

     

  <wsdl:types>

    <xs:schema targetNamespace="http://example.com/stockquote"

      xmlns:xs="http://www.w3.org/2001/XMLSchema">

      <xs:element name="TradePriceRequest">

        <xs:complexType>

          <xs:all>

            <xs:element name="tickerSymbol" type="xs:string"/>

          </xs:all>

        </xs:complexType>

      </xs:element>

      <xs:element name="TradePrice">

        <xs:complexType>

          <xs:all>

            <xs:element name="price" type="xs:float"/>

          </xs:all>

        </xs:complexType>

      </xs:element>

    </xs:schema>

  </wsdl:types>

  

  <wsdl:interface name="StockQuoteInterface">

    <wsdl:operation name="GetLastTradePrice" 

      pattern="http://www.w3.org/@@@@/@@/wsdl/in-out">

      <wsdl:input element="tns:GetLastTradePriceInput">

      	<wsdl:header element="wsse:Security" required="true"
mustUnderstand="true"/>

      </wsdl:input>

      <wsdl:output element="tns:GetLastTradePriceOutput">

        <wsdl:header element="wsse:Security" required="true"
mustUnderstand="true"/>

      </wsdl:output>

    </wsdl:operation>

  </wsdl:interface>

  

  <wsdl:binding name="StockQuoteSoapBinding"
interface="tns:StockQuoteInterface"

    type="http://www.w3.org/@@@@/@@/wsdl/soap" 

    wsoap:protocol="http://www.w3.org/2003/05/soap/bindings/HTTP/">

    <wsdl:operation ref="tns:GetLastTradePrice" 

      wsoap:action="http://example.com/GetLastTradePrice"/>

  </wsdl:binding>

  

  <wsdl:service name="StockQuoteService"
interface="tns:StockQuoteInterface">

    <wsdl:documentation>My first service</wsdl:documentation>

    <wsdl:endpoint name="StockQuoteEndPoint" binding="tns:StockQuoteBinding"


    address="http://example.com/endpoint/stockquote"/>

  </wsdl:service>

  

</wsdl:definitions>

Proposed solution has nine parts:


(1) Introduce a NEW Header Component


Header Component


An Header Component describes an abstract piece of header that is associated
with the exchange of messages between the communicating parties. The
presence of an Header Component in a WSDL description indicates that the
service supports the header and may require a Web Service consumer/client
that interacts with the service to use that header. Zero or more such
headers may be used.


Header Component has 5 properties:


*	{namespace name} REQUIRED. An xs:anyURI. This URI MUST be absolute
as defined by [IETF RFC 2396]. 

*	{local name} REQUIRED. An xs:NCName. 

*	{element} REQUIRED. A reference to an XML element declaration in the
{element declarations} property of The Definitions Component. This element
represents a header. 

*	{required} REQUIRED. An xs:boolean. If the value of this property is
true, then the Web Service consumer/client MUST use the Header that is
identified by the {element declaration}. 

*	{mustUnderstand} OPTIONAL. An xs:boolean. If the property is true,
then the bindings that support expression of mandatory data should mark them
as mandatory in an appropriate way. 


Header Component's XML Representation is,

<header element="xs:QName" mustUnderstand="xs:boolean"?
required="xs:boolean"?>

  <documentation />?

</header>

Header Component's mapping is,


*	{element} = The element declaration from the {element declarations}
property of The Definitions Component resolved to by the value of the
element attribute information item if present, otherwise empty. It is an
error for the element attribute information item to have a value and that
value does not resolve to a global element declaration from the {element
declarations} property of The Definitions Component. 

*	{namespace name} = actual value of the {element declaration}'s
[namespace name] property. 

*	{local name} = actual value of the {element declaration}'s [local
name] property. 

*	{mustUnderstand} = actual value of the mustUnderstand attribute
information item if present, otherwise absent. 

*	{required} = actual value of the required attribute information item
if present, otherwise "false". 


(2) Hook Header Component into the Interface Fault Component


Add the property {headers}


Add the property {headers} to the Interface Fault Component: {headers}
OPTIONAL. A set of Header components.


Modify the XML Representation of Interface Fault Component

<definitions>

  <interface>

    <fault

          name="xs:NCName" 

          element="xs:QName"? >

      <documentation />?

      [ <header /> | <feature /> | <property /> ]*

    </fault>

  </interface>

</definitions>

Modify the Mapping of Interface Fault's XML Representation to Component
Properties


Addition to Table 2-3:

{headers} = The set of Header components corresponding to the header element
information items in [children], if any.


(3) Hook Header Component into the Message Reference Component


Add the property {headers}


Add the property {headers} to the Message Reference Component: {headers}
OPTIONAL. A set of Header components.


Modify the XML Representation of Message Reference Component

<definitions>

  <interface>

    <operation>

      <input

            messageLabel="xs:NCName"?

            element="union of xs:QName, xs:Token"? > 

        <documentation />?

        [ <header /> | <feature /> | <property /> ]*

      </input>

      <output

            messageLabel="xs:NCName"?

            element="union of xs:QName, xs:Token"? >

        <documentation />?

        [ <header /> | <feature /> | <property /> ]*

      </output>

    </operation>

  </interface>

</definitions>

Modify the Mapping of Message Reference's XML Representation to Component
Properties


Addition to Table 2-6:

{headers} = The set of Header components corresponding to the header element
information items in [children], if any.


(4) Syntax Level Default Mechanism to Disable Header Construction


Modify the XML Representation of Binding Component

<definitions>

  <binding

        name="xs:NCName" 

        interface="xs:QName"?

        type="xs:anyURI"

        disableHeadersDefault="xs:boolean"? >

    <documentation />?

    [ <fault /> | <operation /> | <feature /> | <property /> ]*

  </binding>

</definitions>
disableHeaderDefault AII is a syntax level convenient mechanism and does not
contribute anything to the component model. 

(5) Mechanism to Disable Header Construction for the Binding Fault Component


Add the property {disable headers} to Binding Fault Component


{disable headers} OPTIONAL. An xs:boolean. If this property exists and is
true, then header construction is turned off. Scope of {disable headers} is
limited to the WSDL Header components defined for the Interface Fault
Component in {fault reference}. This property does not interact with any
other WSDL feature, Bindings, Extensions or Feature and Properties
framework.


Modify the XML Representation of Binding Fault Component

<definitions>

  <binding>

    <fault

          ref="xs:QName" disableHeaders="xs:boolean"? >

      <documentation />?

      [ <feature /> | <property /> ]*

    </fault>

  </binding>

</definitions>

Modify the Mapping of Binding Fault's XML Representation to Component
Properties


Addition to Table 2-11:

{disable headers} = The actual value of the disableHeaders attribute
information item, if present. If not, the actual value of the
disableHeadersDefault attribute information item of the parent wsdl:binding
element information item, if present. If not the value as defined by the
concrete binding, if applicable.


(6) Mechanism to Disable Header Construction for the Binding Message
Reference Component


Add the property {disable headers} to Binding Message Reference Component


{disable headers} OPTIONAL. An xs:boolean. If this property exists and is
true, then header construction is turned off. Scope of {disable headers} is
limited to the WSDL Header components defined for the Interface Operation
component being bound by the containing Binding Operation component. This
property does not interact with any other WSDL feature, Bindings, Extensions
or Feature and Properties framework.


Modify the XML Representation of Binding Message Reference Component

<definitions>

  <binding>

    <operation>

      <input

            messageLabel="xs:NCName"? disableHeaders="xs:boolean"? >

        <documentation />?

        [ <feature /> | <property /> ]*

      </input>

      <output

            messageLabel="xs:NCName"? disableHeaders="xs:boolean"? >

        <documentation />?

        [ <feature /> | <property /> ]*

      </output>

    </operation>

  </binding>

</definitions>

Modify the Mapping of Binding Fault's XML Representation to Component
Properties


Addition to Table 2-11:

{disable headers} = The actual value of the disableHeaders attribute
information item, if present. If not, the actual value of the
disableHeadersDefault attribute information item of the ancestor
wsdl:binding element information item, if present. If not the value as
defined by the concrete binding, if applicable.


(7) Add to SOAP Binding's Default Binding Rules


SOAP Header block construction


Default value of the Binding element's disableHeadersDefault AII is false.
Default value of the Binding Operation Component's {disable headers}
property is false. 

If the {headers} property exists and non empty, and {disable headers} is
false, element information item conforming to an Header Component's
{element} property in the {headers} property MUST be turned into a SOAP
Header block. 

These elements are serialized according to their schemas, and if the Header
Component's {mustUnderstand} property exists with the value "true", that
particular SOAP header should be marked as "mustUnderstand='true'" or
"mustUnderstand='1'" as per the SOAP specification.


(8) Add to HTTP Binding's Default Binding Rules


HTTP Header construction


Default value of the Binding element's disableHeadersDefault AII is false.
Default value of the Binding Operation Component's {disable headers}
property is false.

If the {headers} property exists and non empty, and {disable headers} is
false, element information item conforming to an Header component's
{element} property in the {headers} property MUST be turned into HTTP header
if possible.

Only element information items of type "xs:string" or "xs:anyURI" may be
serialized. All complex data types are ignored. Attributes on data elements
are ignored.

Each such element information item is serialized as follows:

The HTTP header name used is the element information item local name. The
element information item local name MUST follow the field-name production
rules as specified in section 4.2 of [IETF RFC 2616]; if not, the element
information item MUST be ignored. If an HTTP header corresponding to the
element information item local name is set by a different mechanism other
than the HTTP Binding, such as the HTTP stack or another feature, then an
error MUST be raised.

The HTTP header content is serialized from the corresponding element
information item value in UTF-8. If this serialization is NOT possible, then
the element information item MUST be ignored.


(9) Changes to XML Schema for WSDL 2.0


PENDING