- From: David Orchard via cvs-syncmail <cvsmail@w3.org>
- Date: Wed, 18 Jul 2007 16:42:57 +0000
- To: public-ws-policy-eds@w3.org
Update of /sources/public/2006/ws/policy
In directory hutz:/tmp/cvs-serv4852
Modified Files:
ws-policy-guidelines.xml ws-policy-guidelines.html
Log Message:
4566
Index: ws-policy-guidelines.html
===================================================================
RCS file: /sources/public/2006/ws/policy/ws-policy-guidelines.html,v
retrieving revision 1.87
retrieving revision 1.88
diff -u -d -r1.87 -r1.88
--- ws-policy-guidelines.html 18 Jul 2007 16:11:40 -0000 1.87
+++ ws-policy-guidelines.html 18 Jul 2007 16:42:54 -0000 1.88
@@ -136,10 +136,10 @@
5.4.1 <a href="#parameterized-assertions">Assertions with Parameters</a><br>
5.4.2 <a href="#nested-assertions">Nested Assertions</a><br>
5.5 <a href="#Ignorable">Designating Ignorable Behavior</a><br>
- 5.5.1 <a href="#d3e780">Ignorable behavior in authoring</a><br>
- 5.5.2 <a href="#d3e793">Ignorable behavior at runtime</a><br>
+ 5.5.1 <a href="#d3e795">Ignorable behavior in authoring</a><br>
+ 5.5.2 <a href="#d3e808">Ignorable behavior at runtime</a><br>
5.6 <a href="#optional-policy-assertion">Designating Optional Behaviors</a><br>
- 5.6.1 <a href="#d3e808">Optional behavior at runtime</a><br>
+ 5.6.1 <a href="#d3e823">Optional behavior at runtime</a><br>
5.7 <a href="#levels-of-abstraction">Considerations for Policy Attachment in WSDL </a><br>
5.8 <a href="#interrelated-domains">Interrelated domains</a><br>
6. <a href="#versioning-policy-assertions">Versioning Policy Assertions</a><br>
@@ -201,10 +201,10 @@
the question.
</p></div><div class="div1">
<h2><a name="best-practices-list" id="best-practices-list"></a>2. List of Best Practice Statements</h2><p>The following Best Practices appear in this document with discussion and examples, and are summarized here for quick reference:</p><ul><li><p><a href="#bp-assertion-semantics"><b>1. Semantics Independent of
- Attachment Mechanisms</b></a></p></li><li><p><a href="#bp-compatibility-tests"><b>2. Behaviors Relevant to Compatibility Tests</b></a></p></li><li><p><a href="#bp-semantics-and-form"><b>3. Semantics Independent of the Form</b></a></p></li><li><p><a href="#bp-assertion-start"><b>4. Start with a Simple Assertion</b></a></p></li><li><p><a href="#bp-unique-qnames"><b>5. Use Unique QNames</b></a></p></li><li><p><a href="#XMLOutline"><b>6. Provide an XML Outline</b></a></p></li><li><p><a href="#AssertionDefinitions"><b>7. Specify Semantics Clearly</b></a></p></li><li><p><a href="#DefineIgnorable"><b>8. Assertion Authors Should Document Ignorable Behavior</b></a></p></li><li><p><a href="#ignorableAssertions"><b>9. Assertion Authors Should Document Use of the Ignorable
-Attribute in XML </b></a></p></li><li><p><a href="#bp-assertion-xml-allow-optional"><b>10. Assertion Authors should allow use of wsp:Optional
-attribute</b></a></p></li><li><p><a href="#bp-not-necessary-to-understand-a-message"><b>11. Not Necessary to Understand a Message</b></a></p></li><li><p><a href="#bp-assertion-duplication"><b>12. Avoid Duplication of Assertions</b></a></p></li><li><p><a href="#bp-assertion-parameters"><b>13. Use Parameters for Useful
- Information</b></a></p></li><li><p><a href="#bp-dependent-behaviors"><b>14. Use Nested Assertions for Dependent Behaviors</b></a></p></li><li><p><a href="#bp-declare-nested-assertions"><b>15. Enumerate Nested Assertions</b></a></p></li><li><p><a href="#bp-discourage-domain-specific-intersection"><b>16. Discourage Domain Specific Intersection</b></a></p></li><li><p><a href="#bp-limit-optional-assertions"><b>17. Limit use of Optional Assertions</b></a></p></li><li><p><a href="#bp-entire-mep-for-optional"><b>18. Consider entire message exchange pattern when specifying Assertions that may be optional</b></a></p></li><li><p><a href="#bp-indicate-optional-assertion-use"><b>19. Indicate use of an Optional Assertion</b></a></p></li><li><p><a href="#bp-WSDL-policy-subject"><b>20. Specify Policy Subject(s)</b></a></p></li><li><p><a href="#bp-WSDL-policy-subject-Granularity"><b>21. Choose the Most Granular Policy Subject</b></a></p></li><li><p><a href="#bp-WSDL-multiple-policy-subjects"><b>22. Define Semantics f Attachment to Multiple Policy Subjects</b></a></p></li><li><p><a href="#bp-WSDL-preferred-attachment-point"><b>23. Specify Preferred Attachment Point for an Assertion</b></a></p></li><li><p><a href="#bp-WSDL-policy-multiple-instance-semantics"><b>24. Describe Semantics of Multiple Assertions of Same Type</b></a></p></li><li><p><a href="#bp-specify-composition"><b>25. Specify Composition with Related Assertions</b></a></p></li><li><p><a href="#bp-independent-assertions"><b>26. Use Independent Assertions for Different Versions of a Behavior</b></a></p></li><li><p><a href="#bp-policy-subject-change"><b>27. Change of the Policy Subject Over Time</b></a></p></li></ul></div><div class="div1">
+ Attachment Mechanisms</b></a></p></li><li><p><a href="#bp-compatibility-tests"><b>2. Behaviors Relevant to Compatibility Tests</b></a></p></li><li><p><a href="#bp-ignorable-for-not-related-to-compatibility-tests"><b>3. Mark Ignorable Assertions not related to compatibility</b></a></p></li><li><p><a href="#bp-semantics-and-form"><b>4. Semantics Independent of the Form</b></a></p></li><li><p><a href="#bp-assertion-start"><b>5. Start with a Simple Assertion</b></a></p></li><li><p><a href="#bp-unique-qnames"><b>6. Use Unique QNames</b></a></p></li><li><p><a href="#XMLOutline"><b>7. Provide an XML Outline</b></a></p></li><li><p><a href="#AssertionDefinitions"><b>8. Specify Semantics Clearly</b></a></p></li><li><p><a href="#DefineIgnorable"><b>9. Assertion Authors Should Document Ignorable Behavior</b></a></p></li><li><p><a href="#ignorableAssertions"><b>10. Assertion Authors Should Document Use of the Ignorable
+Attribute in XML </b></a></p></li><li><p><a href="#bp-assertion-xml-allow-optional"><b>11. Assertion Authors should allow use of wsp:Optional
+attribute</b></a></p></li><li><p><a href="#bp-not-necessary-to-understand-a-message"><b>12. Not Necessary to Understand a Message</b></a></p></li><li><p><a href="#bp-assertion-duplication"><b>13. Avoid Duplication of Assertions</b></a></p></li><li><p><a href="#bp-assertion-parameters"><b>14. Use Parameters for Useful
+ Information</b></a></p></li><li><p><a href="#bp-dependent-behaviors"><b>15. Use Nested Assertions for Dependent Behaviors</b></a></p></li><li><p><a href="#bp-declare-nested-assertions"><b>16. Enumerate Nested Assertions</b></a></p></li><li><p><a href="#bp-discourage-domain-specific-intersection"><b>17. Discourage Domain Specific Intersection</b></a></p></li><li><p><a href="#bp-limit-optional-assertions"><b>18. Limit use of Optional Assertions</b></a></p></li><li><p><a href="#bp-entire-mep-for-optional"><b>19. Consider entire message exchange pattern when specifying Assertions that may be optional</b></a></p></li><li><p><a href="#bp-indicate-optional-assertion-use"><b>20. Indicate use of an Optional Assertion</b></a></p></li><li><p><a href="#bp-WSDL-policy-subject"><b>21. Specify Policy Subject(s)</b></a></p></li><li><p><a href="#bp-WSDL-policy-subject-Granularity"><b>22. Choose the Most Granular Policy Subject</b></a></p></li><li><p><a href="#bp-WSDL-multiple-policy-subjects"><b>23. Define Semantics f Attachment to Multiple Policy Subjects</b></a></p></li><li><p><a href="#bp-WSDL-preferred-attachment-point"><b>24. Specify Preferred Attachment Point for an Assertion</b></a></p></li><li><p><a href="#bp-WSDL-policy-multiple-instance-semantics"><b>25. Describe Semantics of Multiple Assertions of Same Type</b></a></p></li><li><p><a href="#bp-specify-composition"><b>26. Specify Composition with Related Assertions</b></a></p></li><li><p><a href="#bp-independent-assertions"><b>27. Use Independent Assertions for Different Versions of a Behavior</b></a></p></li><li><p><a href="#bp-policy-subject-change"><b>28. Change of the Policy Subject Over Time</b></a></p></li></ul></div><div class="div1">
<h2><a name="Assertions" id="Assertions"></a>3. What is an Assertion? </h2><p>An assertion is a piece of metadata that describes a
capability related to a specific WS-Policy domain. Sets of domain-specific assertions
are typically defined in a dedicated specification that describes
@@ -388,12 +388,12 @@
assertion specification:
</p><p>
<ul><li><p>The definition of the assertion's semantic
- (See best practice <a href="#AssertionDefinitions"><b>7. Specify Semantics Clearly</b></a>).</p></li><li><p>The specification of the set of valid policy subjects to which an
+ (See best practice <a href="#AssertionDefinitions"><b>8. Specify Semantics Clearly</b></a>).</p></li><li><p>The specification of the set of valid policy subjects to which an
assertion may be attached
- (See best practice <a href="#bp-WSDL-policy-subject"><b>20. Specify Policy Subject(s)</b></a>).</p></li><li><p>The scope of the assertion in the context of a particular policy
+ (See best practice <a href="#bp-WSDL-policy-subject"><b>21. Specify Policy Subject(s)</b></a>).</p></li><li><p>The scope of the assertion in the context of a particular policy
subject (See best practices in Section <a href="#levels-of-abstraction"><b>5.7 Considerations for Policy Attachment in WSDL </b></a>).</p></li><li><p>Any composition considerations if the assertion is used with
other assertions in a context
- (See best practice <a href="#bp-specify-composition"><b>25. Specify Composition with Related Assertions</b></a>).</p></li></ul>
+ (See best practice <a href="#bp-specify-composition"><b>26. Specify Composition with Related Assertions</b></a>).</p></li></ul>
</p><p>
The WS-Policy Attachment specification defines a number of different
policy subjects to which an assertion can be attached. For attaching to
@@ -417,9 +417,10 @@
The semantics of a policy assertion should not depend on the
attachment mechanism used.</p></div><div class="boxedtext"><p><a name="bp-compatibility-tests" id="bp-compatibility-tests"></a><span class="practicelab">Best
Practice 2: Behaviors Relevant to Compatibility Tests</span></p><p class="practice">
- Whenever possible, Assertion Authors should define policy assertions
- for behaviors that are relevant to compatibility tests, such as web service
- protocols that manifest on the wire.
+ Assertion authors should define assertions for behaviors that are relevant to compatibility assessment, such as web service protocols that manifest on the wire.
+ </p></div><p>Assertion authors may define assertions that are not related to compatibility assessment. These assertions may be used to accurately describe behaviour, even if they do not affect compatibility. WS-Policy has the wsp:Ignorable attribute that may be used for indicating assertions that are not related to compatibility assessment, described in <a href="#Ignorable"><b>5.5 Designating Ignorable Behavior</b></a></p><div class="boxedtext"><p><a name="bp-ignorable-for-not-related-to-compatibility-tests" id="bp-ignorable-for-not-related-to-compatibility-tests"></a><span class="practicelab">Best
+Practice 3: Mark Ignorable Assertions not related to compatibility</span></p><p class="practice">
+ Assertion authors should recommend that assertions that are not relevant to compatibility assessment be marked with the wsp:Ignorable attribute.
</p></div></div><div class="div2">
<h3><a name="compact-full" id="compact-full"></a>5.2 Authoring Styles </h3><p>WS-Policy supports two different authoring styles, compact form and
normal form. A compact form is one in which an expression consists of
@@ -442,7 +443,7 @@
description for a policy assertion should not depend on the style used
to author a policy expression that contains the assertion.
</p><div class="boxedtext"><p><a name="bp-semantics-and-form" id="bp-semantics-and-form"></a><span class="practicelab">Best
-Practice 3: Semantics Independent of the Form</span></p><p class="practice">The semantics of an assertion should be independent of
+Practice 4: Semantics Independent of the Form</span></p><p class="practice">The semantics of an assertion should be independent of
the form (compact or normal form) of policy expressions that contain the
assertion.</p></div><p>
In the example below, the policy expression is shown in its two forms,
@@ -539,7 +540,7 @@
work progresses, one may add more parameters or nested policy assertions
to meet one's interoperability needs.
</p><div class="boxedtext"><p><a name="bp-assertion-start" id="bp-assertion-start"></a><span class="practicelab">Best
-Practice 4: Start with a Simple Assertion</span></p><p class="practice">Assertion Authors should start with a simple working assertion
+Practice 5: Start with a Simple Assertion</span></p><p class="practice">Assertion Authors should start with a simple working assertion
that allows assertion parameter extensibility. </p></div><p>New Assertion Authors are encouraged to look at <cite><a href="#WS-RM-Policy">Web Services Reliable Messaging Policy</a></cite> to see an example of a
relatively simple domain that has defined three assertions. Assertion Authors are encouraged to look at <cite><a href="#WS-SecurityPolicy">WS-SecurityPolicy</a></cite> to see an example of a complex domain that has been decomposed into a set of policy expressions.
</p></div><div class="div3">
@@ -550,8 +551,8 @@
represent an assertion parameter as a child element (by leveraging natural XML nesting)
or an attribute of an assertion. The general guidelines on when to use XML elements
versus attributes apply. Use a unique QName to identify a distinct behavior.</p><div class="boxedtext"><p><a name="bp-unique-qnames" id="bp-unique-qnames"></a><span class="practicelab">Best
-Practice 5: Use Unique QNames</span></p><p class="practice">Assertion Authors should use a unique QName to identify a distinct behavior.</p></div><div class="boxedtext"><p><a name="XMLOutline" id="XMLOutline"></a><span class="practicelab">Best
-Practice 6: Provide an XML Outline</span></p><p class="practice">Assertion authors should provide an XML outline plus an XML schema to
+Practice 6: Use Unique QNames</span></p><p class="practice">Assertion Authors should use a unique QName to identify a distinct behavior.</p></div><div class="boxedtext"><p><a name="XMLOutline" id="XMLOutline"></a><span class="practicelab">Best
+Practice 7: Provide an XML Outline</span></p><p class="practice">Assertion authors should provide an XML outline plus an XML schema to
specify the syntax of an assertion.
</p></div><p> An example of this method (below) is given in the Web Services Reliable Messaging Policy document. [<cite><a href="#WS-RM-Policy">Web Services Reliable Messaging Policy</a></cite>]
</p><div class="exampleOuter"><div class="exampleInner"><pre>
@@ -588,14 +589,14 @@
</sp:IssuedToken>
</pre></div></div><div class="boxedtext"><p><a name="AssertionDefinitions" id="AssertionDefinitions"></a><span class="practicelab">Best
-Practice 7: Specify Semantics Clearly</span></p><p class="practice"> Assertion authors should clearly and completely specify the
+Practice 8: Specify Semantics Clearly</span></p><p class="practice"> Assertion authors should clearly and completely specify the
semantics of a policy assertion.
</p></div><div class="boxedtext"><p><a name="DefineIgnorable" id="DefineIgnorable"></a><span class="practicelab">Best
-Practice 8: Assertion Authors Should Document Ignorable Behavior</span></p><p class="practice">An assertion description should include guidance as to the use of (or
+Practice 9: Assertion Authors Should Document Ignorable Behavior</span></p><p class="practice">An assertion description should include guidance as to the use of (or
constraint against the use of) the wsp:Ignorable attribute to indicate
whether or not the behavior indicated by the QName may be ignored by policy
intersection. </p></div><div class="boxedtext"><p><a name="ignorableAssertions" id="ignorableAssertions"></a><span class="practicelab">Best
-Practice 9: Assertion Authors Should Document Use of the Ignorable
+Practice 10: Assertion Authors Should Document Use of the Ignorable
Attribute in XML </span></p><p class="practice"> An Assertion Author should document, in the XML outline and/or schema for
the assertion, whether or not the assertion allows for the use of the wsp:Ignorable attribute.
</p></div><p>To give an example, the WS-ReliableMessaging Policy document specifies attribute extensibility as part of the XML definition, allowing the wsp:Ignorable attribute:
@@ -609,7 +610,7 @@
for the use of the wsp:Optional attribute in the XML outline and/or schema
definition of an assertion as this will allow policy expression authors to
compose compact policy expressions.</p><div class="boxedtext"><p><a name="bp-assertion-xml-allow-optional" id="bp-assertion-xml-allow-optional"></a><span class="practicelab">Best
-Practice 10: Assertion Authors should allow use of wsp:Optional
+Practice 11: Assertion Authors should allow use of wsp:Optional
attribute</span></p><p class="practice">An assertion's XML outline and/or schema definition should allow the use
of the wsp:Optional attribute so as to enable policy authors to compose
compact policy expressions.</p></div><p>For example, consider the following two equivalent policy expressions:</p><div class="exampleOuter">
@@ -660,7 +661,7 @@
their assertions by specifying additional properties, headers,
etc. that must be present in a message as part of their assertion design.
</p><div class="boxedtext"><p><a name="bp-not-necessary-to-understand-a-message" id="bp-not-necessary-to-understand-a-message"></a><span class="practicelab">Best
-Practice 11: Not Necessary to Understand a Message</span></p><p class="practice">Assertion Authors should not define policy assertions to represent information that is necessary to understand a message.</p></div><p>For example, if the details of a message's encryption ( e.g., the cipher used, etc) are expressed
+Practice 12: Not Necessary to Understand a Message</span></p><p class="practice">Assertion Authors should not define policy assertions to represent information that is necessary to understand a message.</p></div><p>For example, if the details of a message's encryption ( e.g., the cipher used, etc) are expressed
in policy that isn't attached to the message, it isn't possible
to later decipher it. This is very different from expressing, in
policy, what ciphers (and so forth) are supported by a particular
@@ -690,7 +691,7 @@
</p><p>It is the responsibility of the Assertion Authors to avoid duplication of assertions.
A review by a broad community is the best way to ensure that the granularity of a set
of domain assertions is appropriate.</p><div class="boxedtext"><p><a name="bp-assertion-duplication" id="bp-assertion-duplication"></a><span class="practicelab">Best
-Practice 12: Avoid Duplication of Assertions</span></p><p class="practice">Assertion Authors should reuse an existing assertion (rather than create a new one) whenever possible.</p></div></div></div><div class="div2">
+Practice 13: Avoid Duplication of Assertions</span></p><p class="practice">Assertion Authors should reuse an existing assertion (rather than create a new one) whenever possible.</p></div></div></div><div class="div2">
<h3><a name="comparison" id="comparison"></a>5.4 Comparison of Nested and Parameterized Assertions</h3><p>There are two different ways to provide additional information in an
assertion beyond its type. We cover these two cases below followed by a
comparison of these approaches targeting when to use either of the approach.
@@ -705,7 +706,7 @@
domain specific processing for policy intersection.</p><p>In the XML representation of a policy assertion, the child elements
and attributes of the assertion excluding child elements and attributes
from the policy language namespace name are the assertion parameters.</p><div class="boxedtext"><p><a name="bp-assertion-parameters" id="bp-assertion-parameters"></a><span class="practicelab">Best
-Practice 13: Use Parameters for Useful
+Practice 14: Use Parameters for Useful
Information</span></p><p class="practice">Assertion Authors should represent useful (or additional)
information necessary for engaging the behavior represented by a policy
assertion as assertion parameters.
@@ -738,10 +739,10 @@
that are allowed. There is one caveat to watch out for: policy assertions
with deeply nested policy can greatly increase the complexity of a policy and should be
avoided when they are not needed.</p><div class="boxedtext"><p><a name="bp-dependent-behaviors" id="bp-dependent-behaviors"></a><span class="practicelab">Best
-Practice 14: Use Nested Assertions for Dependent Behaviors</span></p><p class="practice">Assertion Authors should represent dependent behaviors that are relevant
+Practice 15: Use Nested Assertions for Dependent Behaviors</span></p><p class="practice">Assertion Authors should represent dependent behaviors that are relevant
to a compatibility test and apply to the same policy subject using
nested policy assertions.</p></div><div class="boxedtext"><p><a name="bp-declare-nested-assertions" id="bp-declare-nested-assertions"></a><span class="practicelab">Best
-Practice 15: Enumerate Nested Assertions</span></p><p class="practice">If there is a nested policy expression, then the Assertion Authors
+Practice 16: Enumerate Nested Assertions</span></p><p class="practice">If there is a nested policy expression, then the Assertion Authors
should enumerate the nested policy assertions that are allowed.</p></div><p>The main consideration for selecting parameters or nesting
of assertions is that <em>the framework intersection
algorithm processes nested alternatives, but does not consider
@@ -763,7 +764,7 @@
delegated to the specific domain handlers that are not visible
to the WS-Policy framework. However, domain specific intersection processing reduces
interop and increases the burden to implement an assertion.</p><div class="boxedtext"><p><a name="bp-discourage-domain-specific-intersection" id="bp-discourage-domain-specific-intersection"></a><span class="practicelab">Best
-Practice 16: Discourage Domain Specific Intersection</span></p><p class="practice">Assertion authors should only specify domain specific
+Practice 17: Discourage Domain Specific Intersection</span></p><p class="practice">Assertion authors should only specify domain specific
intersection semantics when policy intersection is insufficient.</p></div><p>We will use the WS-SecurityPolicy to illustrate the use of nested assertions.
</p><p>Securing messages is a complex usage scenario. The WS-SecurityPolicy Assertion Authors have defined the
<code>sp:TransportBinding</code> policy assertion to indicate
@@ -850,23 +851,23 @@
certificate will not be able to use this provider solely on the basis
of intersection algorithm alone.</p></div></div><div class="div2">
<h3><a name="Ignorable" id="Ignorable"></a>5.5 Designating Ignorable Behavior</h3><div class="div3">
-<h4><a name="d3e780" id="d3e780"></a>5.5.1 Ignorable behavior in authoring</h4><p>
- The Policy Framework provides an intersection algorithm that has two defined modes for processing (lax and strict). The Framework also defines an attribute (wsp:Ignorable) that can be used to influence whether assertions are part of the compatability assessment between two alternatives. [see <cite><a href="#WS-Policy">Web Services Policy Framework</a></cite> and <cite><a href="#WS-Policy-Primer">Web Services Policy Primer</a></cite>]. Assertion authors should consider whether the behavior represented by the Assertion they are defining can be safely ignored for the purposes of intersection, and should follow <a href="#DefineIgnorable"><b>8. Assertion Authors Should Document Ignorable Behavior</b></a> and <a href="#ignorableAssertions"><b>9. Assertion Authors Should Document Use of the Ignorable
+<h4><a name="d3e795" id="d3e795"></a>5.5.1 Ignorable behavior in authoring</h4><p>
+ The Policy Framework provides an intersection algorithm that has two defined modes for processing (lax and strict). The Framework also defines an attribute (wsp:Ignorable) that can be used to influence whether assertions are part of the compatability assessment between two alternatives. [see <cite><a href="#WS-Policy">Web Services Policy Framework</a></cite> and <cite><a href="#WS-Policy-Primer">Web Services Policy Primer</a></cite>]. Assertion authors should consider whether the behavior represented by the Assertion they are defining can be safely ignored for the purposes of intersection, and should follow <a href="#DefineIgnorable"><b>9. Assertion Authors Should Document Ignorable Behavior</b></a> and <a href="#ignorableAssertions"><b>10. Assertion Authors Should Document Use of the Ignorable
Attribute in XML </b></a> to include this guidance in the assertion's definition.</p></div><div class="div3">
-<h4><a name="d3e793" id="d3e793"></a>5.5.2 Ignorable behavior at runtime</h4><p>Regardless of whether the assertion allows the ignorable attribute, assertion authors should
+<h4><a name="d3e808" id="d3e808"></a>5.5.2 Ignorable behavior at runtime</h4><p>Regardless of whether the assertion allows the ignorable attribute, assertion authors should
indicate the semantic of the runtime behavior in the description of the assertion.
</p><p>
As said in <a href="ws-policy-primer.html#strict-lax-policy-intersection">section 3.4.1 Strict and Lax Policy Intersection</a> in <cite><a href="#WS-Policy-Primer">Web Services Policy Primer</a></cite>, "Regardless of the chosen intersection mode, ignorable assertions do not express any wire-level requirements on the behavior of consumers - in other words, a consumer could choose to ignore any such assertions that end up in the resulting policy after intersection, with no adverse effects on runtime interactions." Therefore, any assertion that is marked with ignorable should not impose any wire-level requirements on the part of consumers. Assertion Authors are reminded that regardless of whether an assertion is marked as ignorable, policy consumers using strict intersection will not 'ignore' the assertion.
</p></div></div><div class="div2">
<h3><a name="optional-policy-assertion" id="optional-policy-assertion"></a>5.6 Designating Optional Behaviors</h3><div class="div3">
-<h4><a name="d3e808" id="d3e808"></a>5.6.1 Optional behavior at runtime</h4><table border="1" summary="Editorial note"><tr><td align="left" valign="top" width="50%"><b>Editorial note</b></td><td align="right" valign="top" width="50%"> </td></tr><tr><td colspan="2" align="left" valign="top">This section does not have Working Group consensus and there is an outstanding action item to revise it</td></tr></table><p>Since optional behaviors indicate optionality for
+<h4><a name="d3e823" id="d3e823"></a>5.6.1 Optional behavior at runtime</h4><table border="1" summary="Editorial note"><tr><td align="left" valign="top" width="50%"><b>Editorial note</b></td><td align="right" valign="top" width="50%"> </td></tr><tr><td colspan="2" align="left" valign="top">This section does not have Working Group consensus and there is an outstanding action item to revise it</td></tr></table><p>Since optional behaviors indicate optionality for
both the provider and the consumer, behaviors that must
always be engaged by a consumer must not be marked as
"optional" with a value "true" since this would allow the
consumer to select the policy alternative that does not contain the assertion,
and thus not engaging the behavior.
</p><div class="boxedtext"><p><a name="bp-limit-optional-assertions" id="bp-limit-optional-assertions"></a><span class="practicelab">Best
-Practice 17: Limit use of Optional Assertions</span></p><p class="practice">Assertion Authors should not use optional assertions for behaviors that must be present
+Practice 18: Limit use of Optional Assertions</span></p><p class="practice">Assertion Authors should not use optional assertions for behaviors that must be present
in compatible policy expressions.</p></div><p> The target scope of an optional assertion is an important factor for
Assertion Authors to consider as it determines the
<em>granularity</em> where the behavior is optionally
@@ -898,7 +899,7 @@
assertions and require the use of endpoint policy subject
when message policy subject is used via attachment.
</p><div class="boxedtext"><p><a name="bp-entire-mep-for-optional" id="bp-entire-mep-for-optional"></a><span class="practicelab">Best
-Practice 18: Consider entire message exchange pattern when specifying Assertions that may be optional</span></p><p class="practice">Assertion Authors should associate optional assertions with the appropriate endpoint and use the smallest
+Practice 19: Consider entire message exchange pattern when specifying Assertions that may be optional</span></p><p class="practice">Assertion Authors should associate optional assertions with the appropriate endpoint and use the smallest
possible granularity to limit the degree to which optionality applies.</p></div><p>
Behaviors must be engaged
with respect to messages that are targeted to the provider
@@ -912,7 +913,7 @@
(Such an out of band mechanism is outside the scope of WS-Policy
Framework).
</p><div class="boxedtext"><p><a name="bp-indicate-optional-assertion-use" id="bp-indicate-optional-assertion-use"></a><span class="practicelab">Best
-Practice 19: Indicate use of an Optional Assertion</span></p><p class="practice">When a given behavior may be optional, it must be possible for both message participants to determine that the assertion is selected by both parties,
+Practice 20: Indicate use of an Optional Assertion</span></p><p class="practice">When a given behavior may be optional, it must be possible for both message participants to determine that the assertion is selected by both parties,
either out of band or as reflected by the message content.</p></div><p>
The <cite><a href="#WS-Policy-Primer">Web Services Policy Primer</a></cite> document contains an example that outlines the
use of
@@ -950,7 +951,7 @@
made using an endpoint then the subject is the endpoint policy subject. </p></li><li><p>If the behavior applies to any message exchange
defined by an operation then the subject is the operation policy subject. </p></li><li><p>If the behavior applies to an input message then
the subject is the message policy subject - similarly for output and fault message policy subjects.</p></li></ul><div class="boxedtext"><p><a name="bp-WSDL-policy-subject" id="bp-WSDL-policy-subject"></a><span class="practicelab">Best
-Practice 20: Specify Policy Subject(s)</span></p><p class="practice">Assertion Authors should specify the set of relevant policy subjects with which
+Practice 21: Specify Policy Subject(s)</span></p><p class="practice">Assertion Authors should specify the set of relevant policy subjects with which
the assertion may be associated. For instance, if a policy assertion is to be used with
WSDL, the assertion description should specify a WSDL policy subject - such as service,
endpoint, operation and message.
@@ -983,7 +984,7 @@
policy attachments to policy subjects of broader scope and granularity
should be done only after careful evaluation.
</p><div class="boxedtext"><p><a name="bp-WSDL-policy-subject-Granularity" id="bp-WSDL-policy-subject-Granularity"></a><span class="practicelab">Best
-Practice 21: Choose the Most Granular Policy Subject</span></p><p class="practice">Assertion Authors should choose the most granular policy subject
+Practice 22: Choose the Most Granular Policy Subject</span></p><p class="practice">Assertion Authors should choose the most granular policy subject
to which the behavior represented by a policy assertion applies.
</p></div><p>
For authoring convenience, Assertion Authors may allow the
@@ -994,7 +995,7 @@
same assertion attached to different policy subjects at the same
time in order to avoid conflicting behavior.
</p><div class="boxedtext"><p><a name="bp-WSDL-multiple-policy-subjects" id="bp-WSDL-multiple-policy-subjects"></a><span class="practicelab">Best
-Practice 22: Define Semantics of Attachment to Multiple Policy Subjects</span></p><p class="practice">If an assertion is allowed to be associated with multiple policy subjects,
+Practice 23: Define Semantics of Attachment to Multiple Policy Subjects</span></p><p class="practice">If an assertion is allowed to be associated with multiple policy subjects,
the assertion author should describe the semantics of multiple instances of
the same assertion attached to multiple policy subjects at the same time.
</p></div><p>If the capability is not really suitable and may imply
@@ -1015,7 +1016,7 @@
when the policy assertions do not target wire-level behaviors but
rather abstract requirements, this technique does not apply.
</p><div class="boxedtext"><p><a name="bp-WSDL-preferred-attachment-point" id="bp-WSDL-preferred-attachment-point"></a><span class="practicelab">Best
-Practice 23: Specify Preferred Attachment Point for an Assertion</span></p><p class="practice">If an assertion can be attached at multiple attachment points
+Practice 24: Specify Preferred Attachment Point for an Assertion</span></p><p class="practice">If an assertion can be attached at multiple attachment points
within a policy subject, Assertion Authors should specify a
preferred attachment point for the chosen policy subject.
</p></div><p>Assertion Authors that utilize WSDL policy subjects need to
@@ -1034,7 +1035,7 @@
same alternative. However, the clear semantics defined by the SignedParts
assertion enable processing of the multiple occurrences properly.
</p><div class="boxedtext"><p><a name="bp-WSDL-policy-multiple-instance-semantics" id="bp-WSDL-policy-multiple-instance-semantics"></a><span class="practicelab">Best
-Practice 24: Describe Semantics of Multiple Assertions of Same Type</span></p><p class="practice">A policy alternative can contain multiple instances of the same
+Practice 25: Describe Semantics of Multiple Assertions of Same Type</span></p><p class="practice">A policy alternative can contain multiple instances of the same
policy assertion type. Assertion authors should specify the semantics of
multiple instances of same policy assertion type in the same policy
alternative and the semantics of parameters and nested policy (if any)
@@ -1046,7 +1047,7 @@
assertions and should also make sure that when adding assertions those new assertions are consistent
with pre-existing assertions of any
interrelated domain. </p><div class="boxedtext"><p><a name="bp-specify-composition" id="bp-specify-composition"></a><span class="practicelab">Best
-Practice 25: Specify Composition with Related Assertions</span></p><p class="practice">Assertion authors should clearly specify how an assertion
+Practice 26: Specify Composition with Related Assertions</span></p><p class="practice">Assertion authors should clearly specify how an assertion
may compose with other related assertions, if any.</p></div><p> A
classic example of such an interrelated domain is security, because
security tends to
@@ -1089,7 +1090,7 @@
[<cite><a href="#WS-Addressing">WS-Addressing Core</a></cite>]. These equivalent behaviors
are mutually exclusive for an interaction. Such equivalent
behaviors can be modeled as independent assertions. </p><div class="boxedtext"><p><a name="bp-independent-assertions" id="bp-independent-assertions"></a><span class="practicelab">Best
-Practice 26: Use Independent Assertions for Different Versions of a Behavior</span></p><p class="practice">Assertion Authors should use independent assertions for modeling different
+Practice 27: Use Independent Assertions for Different Versions of a Behavior</span></p><p class="practice">Assertion Authors should use independent assertions for modeling different
versions of a behavior.</p></div><p>The
policy expression in the example below requires the use of
WSS: SOAP Message Security 1.0. </p><div class="exampleOuter">
@@ -1102,7 +1103,7 @@
<sp:Wss11>…</sp:Wss11>
</Policy></pre></div></div></div><div class="div2">
<h3><a name="supporting-new-policy-subjects" id="supporting-new-policy-subjects"></a>6.3 Supporting New Policy Subjects</h3><p>
- The best practice <a href="#bp-WSDL-policy-subject"><b>20. Specify Policy Subject(s)</b></a> specifies that policy authors should
+ The best practice <a href="#bp-WSDL-policy-subject"><b>21. Specify Policy Subject(s)</b></a> specifies that policy authors should
define the set of policy subjects to which policy assertions can be
attached. Over time, new policy subjects may need to be defined. When
this occurs, policy Assertion Authors may update the list of policy
@@ -1118,7 +1119,7 @@
new policy subjects are added it is incumbent on the authors to retain the
semantic of the policy assertion.
</p><div class="boxedtext"><p><a name="bp-policy-subject-change" id="bp-policy-subject-change"></a><span class="practicelab">Best
-Practice 27: Change of the Policy Subject Over Time</span></p><p class="practice">If the policy subjects change over time,
+Practice 28: Change of the Policy Subject Over Time</span></p><p class="practice">If the policy subjects change over time,
the assertion description should also be versioned to reflect this
change.</p></div></div></div></div><div class="back"><div class="div1">
<h2><a name="security-considerations" id="security-considerations"></a>A. Security Considerations</h2><p> Security considerations are discussed in the <cite><a href="#WS-Policy">Web Services Policy Framework</a></cite> document.</p></div><div class="div1">
@@ -1446,12 +1447,12 @@
are reflected.
</td></tr><tr><td rowspan="1" colspan="1">20070518</td><td rowspan="1" colspan="1">PY</td><td rowspan="1" colspan="1">Updated Appendix E, Changes in this Version of the Document
(<a href="#change-description"><b>E. Changes in this Version of the Document</b></a>).
- </td></tr><tr><td rowspan="1" colspan="1">20070520</td><td rowspan="1" colspan="1">ASV</td><td rowspan="1" colspan="1">Added Best Practice <a href="#bp-specify-composition"><b>25. Specify Composition with Related Assertions</b></a> (from
+ </td></tr><tr><td rowspan="1" colspan="1">20070520</td><td rowspan="1" colspan="1">ASV</td><td rowspan="1" colspan="1">Added Best Practice <a href="#bp-specify-composition"><b>26. Specify Composition with Related Assertions</b></a> (from
the <a href="http://lists.w3.org/Archives/Public/public-ws-policy/2007Mar/att-0069/good-practices-4-assertion-authors-03-05-2007.pdf">IBM
and MS Contribution</a> to
<a href="#interrelated-domains"><b>5.8 Interrelated domains</b></a>. Added an ed note that
Section <a href="#interrelated-domains"><b>5.8 Interrelated domains</b></a> needs to be re-structured.
- </td></tr><tr><td rowspan="1" colspan="1">20070520</td><td rowspan="1" colspan="1">ASV</td><td rowspan="1" colspan="1">Added Best Practice <a href="#bp-not-necessary-to-understand-a-message"><b>11. Not Necessary to Understand a Message</b></a> (from
+ </td></tr><tr><td rowspan="1" colspan="1">20070520</td><td rowspan="1" colspan="1">ASV</td><td rowspan="1" colspan="1">Added Best Practice <a href="#bp-not-necessary-to-understand-a-message"><b>12. Not Necessary to Understand a Message</b></a> (from
the <a href="http://lists.w3.org/Archives/Public/public-ws-policy/2007Mar/att-0069/good-practices-4-assertion-authors-03-05-2007.pdf">IBM
and MS Contribution</a> to
<a href="#self-describing"><b>5.3.3 Self Describing Messages </b></a>.
@@ -1535,4 +1536,7 @@
<a href="http://www.w3.org/2005/06/tracker/wspolicyeds/actions/342">342</a>, <a href="http://www.w3.org/2005/06/tracker/wspolicyeds/actions/346">346</a>. </td></tr><tr><td rowspan="1" colspan="1">20070718</td><td rowspan="1" colspan="1">DBO</td><td rowspan="1" colspan="1">Implemented the resolution
for issue <a href="http://www.w3.org/Bugs/Public/show_bug.cgi?id=4664">4664</a>.
Editors' action:
- <a href="http://www.w3.org/2005/06/tracker/wspolicyeds/actions/343">343</a>. </td></tr></tbody></table><br></div></div></body></html>
\ No newline at end of file
+ <a href="http://www.w3.org/2005/06/tracker/wspolicyeds/actions/343">343</a>. </td></tr><tr><td rowspan="1" colspan="1">20070718</td><td rowspan="1" colspan="1">DBO</td><td rowspan="1" colspan="1">Implemented the resolution
+ for issue <a href="http://www.w3.org/Bugs/Public/show_bug.cgi?id=4566">4566</a>.
+ Editors' action:
+ <a href="http://www.w3.org/2005/06/tracker/wspolicyeds/actions/249">249</a>, <a href="http://www.w3.org/2005/06/tracker/wspolicyeds/actions/328">328</a>. </td></tr></tbody></table><br></div></div></body></html>
\ No newline at end of file
Index: ws-policy-guidelines.xml
===================================================================
RCS file: /sources/public/2006/ws/policy/ws-policy-guidelines.xml,v
retrieving revision 1.102
retrieving revision 1.103
diff -u -d -r1.102 -r1.103
--- ws-policy-guidelines.xml 18 Jul 2007 16:11:40 -0000 1.102
+++ ws-policy-guidelines.xml 18 Jul 2007 16:42:53 -0000 1.103
@@ -486,9 +486,14 @@
<p role="practice" id="bp-compatibility-tests">
<quote>Behaviors Relevant to Compatibility Tests</quote>
<quote>
- Whenever possible, Assertion Authors should define policy assertions
- for behaviors that are relevant to compatibility tests, such as web service
- protocols that manifest on the wire.
+ Assertion authors should define assertions for behaviors that are relevant to compatibility assessment, such as web service protocols that manifest on the wire.
+ </quote>
+ </p>
+ <p>Assertion authors may define assertions that are not related to compatibility assessment. These assertions may be used to accurately describe behaviour, even if they do not affect compatibility. WS-Policy has the wsp:Ignorable attribute that may be used for indicating assertions that are not related to compatibility assessment, described in <specref ref="Ignorable"/></p>
+ <p role="practice" id="bp-ignorable-for-not-related-to-compatibility-tests">
+ <quote>Mark Ignorable Assertions not related to compatibility</quote>
+ <quote>
+ Assertion authors should recommend that assertions that are not relevant to compatibility assessment be marked with the wsp:Ignorable attribute.
</quote>
</p>
</div2>
@@ -2496,6 +2501,15 @@
for issue <loc href="http://www.w3.org/Bugs/Public/show_bug.cgi?id=4664">4664</loc>.
Editors' action:
<loc href="http://www.w3.org/2005/06/tracker/wspolicyeds/actions/343">343</loc>. </td>
+</tr>
+
+<tr>
+<td>20070718</td>
+<td>DBO</td>
+ <td>Implemented the resolution
+ for issue <loc href="http://www.w3.org/Bugs/Public/show_bug.cgi?id=4566">4566</loc>.
+ Editors' action:
+ <loc href="http://www.w3.org/2005/06/tracker/wspolicyeds/actions/249">249</loc>, <loc href="http://www.w3.org/2005/06/tracker/wspolicyeds/actions/328">328</loc>. </td>
</tr>
</tbody>
</table>
Received on Wednesday, 18 July 2007 16:43:00 UTC