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XCAP Tutorial Jonathan Rosenberg.

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1 XCAP Tutorial Jonathan Rosenberg

2 Ground Rules This is a session for level setting
People are at different points We will start from the beginning NO QUESTION IS TOO STUPID Disrespect will not be tolerated Please interrupt and ask PLEASE!

3 Agenda Understanding XML HTTP Concepts of Note XCAP Problem Definition
Basic XML Concepts Namespaces Schema XPath in Brief HTTP Concepts of Note Etags XCAP Problem Definition XCAP Basics

4 XML Basics XML is a mechanism for representing structured data
Data is represented by a tree Each node in the tree is an element Elements have attributes Attributes qualify the data “Leaf” Elements can contain text content <?xml version="1.0" encoding="UTF-8"?> <address-book> <!—This guy is a bozo -- <entry> <name>Jonathan Rosenberg</name> <postal> <street paved=“true”>600 Lanidex Pl</street> <city>Parsippany</city> <state>NJ</state> <country>USA</country> </postal> <ietf-participant/> </entry> </address-book>

5 XML Basics XML Comments Elements can be empty XML Declaration
<el-name/> shorthand XML Declaration Version Encoding IETF uses UTF-8 <?xml version="1.0" encoding="UTF-8"?> <address-book> <!—This guy is a bozo -- <entry> <name>Jonathan Rosenberg</name> <postal> <street paved=“true”>600 Lanidex Pl</street> <city>Parsippany</city> <state>NJ</state> <country>USA</country> </postal> <ietf-participant/> </entry> </address-book>

6 XML Terms Well-formed Valid
Meets basic constraints for all XML documents Each open tag has a matching close Unique attribute names Valid Meets the constraints defined by a schema or DTD

7 XML Namespaces Problem Example
Want to combine content from different systems into one document What if both sources define the same name? Example Add information to address book on whether data is synced with PC <state>synchronized</state> Which state is it? <?xml version="1.0" encoding="UTF-8"?> <address-book> <!—This guy is a bozo -- <entry> <name>Jonathan Rosenberg</name> <postal> <street paved=“true”>600 Lanidex Pl</street> <city>Parsippany</city> <state>NJ</state> <country>USA</country> </postal> <ietf-participant/> </entry> </address-book>

8 XML Namespaces Solution: XML Namespace
<?xml version="1.0" encoding="UTF-8"? xmlns:post=“http://www.post.com” xmlns:sync=“http://www.sync.com”> <post:address-book> <!—This guy is a bozo -- <post:entry> <post:name>Jonathan Rosenberg</post:name> <post:postal> <post:street paved=“true”>600 Lanidex Pl</post:street> <post:city>Parsippany</post:city> <post:state>NJ</post:state> <post:country>USA</post:country> </post:postal> <post:ietf-participant/> <sync:state>synchronized</sync:state> </entry> </address-book> Solution: XML Namespace Elements and attributes are bound to a namespace when defined Namespace is identified with a unique URI A prefix is bound to that URI through a declaration in the document Each element is named with its qualified name The prefix, followed by a colon, followed by the local-name

9 Importance of Namespaces
Namespaces are like option tags in SIP Group a bunch of things together and give it a name Are useful for talking about extensibility Are useful for negotiating extensibility Provide a generic grouping facility

10 XML Schema Need a way to define the constraints on an XML document
Analagous to a database schema Similar to a grammar W3C has specified two ways DTD Original method Not an XML document Limited expressiveness Schema Newer XML-based Much more expressive Much more complex Works well with namespaces Trend is towards schema

11 Schema Example <?xml version="1.0" encoding="UTF-8"?>
<xs:schema targetNamespace="http://www.post.com" xmlns:xs="http://www.w3.org/2001/XMLSchema" xmlns="http://www.post.com" elementFormDefault="qualified" attributeFormDefault="unqualified"> <xs:element name="address-book"> <xs:complexType> <xs:sequence> <xs:element name="entry" minOccurs="0" maxOccurs="unbounded"> <xs:element name="name" type="xs:string"/> <xs:element name=" " type="xs:string"/> <xs:element name="postal"> <xs:element name="street" type="xs:string"/> <xs:element name="city" type="xs:string"/> <xs:element name="state"> <xs:simpleType> <xs:restriction base="xs:string"> <xs:enumeration value="NJ"/> <xs:enumeration value="NY"/> </xs:restriction> </xs:simpleType> </xs:element> <xs:element name="country" type="xs:string"/> </xs:sequence> </xs:complexType> <xs:element name="ietf-participant"/> </xs:schema>

12 XPath XCAP selection is based on XPath XPath problem statement
Happens to be a subset Not a normative usage XPath problem statement How to point to specific pieces of an XML document Example: “The third element named entry” Example: “All of the elements in a document that have the attribute paved equal to true.” XPath = XML Addressing

13 Basic Example Want to point to the email element
<?xml version="1.0" encoding="UTF-8"? xmlns:post=“http://www.post.com” xmlns:sync=http://www.sync.com xmlns=“http://www.post.com”> <address-book> <!—This guy is a bozo -- <entry> <name>Jonathan R<name> <postal> <street paved=“true”>600 Lx Pl</street> <city>Parsippany</city> <state>NJ</state> <country>USA</country> </postal> <ietf-participant/> <sync:state>synchronized</sync:state> </entry> </address-book> Want to point to the element XPath expression address-book/entry/ Just like a unix filesystem path Each “directory” identifies an element name

14 Positional Selectors What if there are multiple elements with that name? Can supply predicates which select one of the matching ones Predicates appear in square brackets One such predicate is position Indicates which one by its place in the ordered sequence of matching elements Select second bar: foo/bar[2] Select first bar: foo/bar[1] <foo> <bar>Hello</bar> <bar>There</bar> </foo>

15 Select by Attribute Name
You can select elements that have attributes with specific values <foo> <bar attr=“1”>Hi</bar> <bar attr=“2”>How</bar> <bar stuff=“LOTR”>Are</bar> </foo>

16 Selecting Elements The result of selecting an element includes
The element Its children Its attributes Everything between open bracket of open element to close bracket of close element XPath allows selecting multiple elements XCAP does not use this feature

17 Selecting Attributes An attribute is selected by prefixing its name with an The selected object is JUST the value Different from elements Name would be redundant <foo> <bar attr=“1”>Hi</bar> <bar attr=“2” bool=“y”>How</bar> <movie stuff=“LOTR”>Are</bar> </foo>

18 XCAP Problem Space Motivating use cases Buddy Lists
Authorization Policies Hard state presence data

19 Buddy List Use Case Client wants to subscribe to a list of users
Subscribe List Client wants to subscribe to a list of users Send SUBSCRIBE to server using SIP event list extension Server retrieves list associated with buddylist URI Generates SUBSCRIBEs to them Client can manage that list Add, remove, modify entries Subscribe Joe Subscribe Bob Subscribe Mary Read List Write List Data Manipulation Server Standard Ifaces Client

20 Authorization Use Case
Subscribe Petri User Hiroshi subscribes to Petri No auth policy in place, generates a winfo NOTIFY to Petri Petri needs to be able to set authorization decision for Hiroshi Want to be able to set such policies outside of a subscription as well Read List Write List Data Manipulation Server winfo Standard Ifaces Client

21 Hard State Presence Management
Subscribe Petri Hiroshi subscribes to Petri Petri has been offline for weeks Server sends NOTIFY with current presence state Petri wants to control default state when offline Set it to <activity>vacation</activity> Notify Read PIDF Write PIDF Data Manipulation Server Standard Ifaces Client

22 Functional Requirements
Create resource list/auth policies/default presence doc Associate resource list/auth policies/default presence doc with URI Have client define URI Have server assign URI Modify contents of resource list/auth policies/default presence doc Extend resource list/auth policies/default presence doc in hierarchical way Delete a piece of resource list/auth policies/default presence doc Fetch current resource list/auth policies/default presence doc Allow multiple clients to access and modify a shared resource list/auth policies/default presence doc

23 Performance Requirements
Protocol will be used on wireless air interfaces Means that it is unacceptable to push the entire resource list/auth policies/default presence doc when a change is needed Unacceptable to get the entire resource list/auth policies/default presence doc when the client needs to look at it Implies local cache Pushing and pulling partial pieces of the data is essential Invalidation of cached data Synchronization of data

24 Key Observations Clearly a general problem here
Allowing a user to managed provisioned data that is accessed by a network application Apply some basic design principles Separate protocol machinery from data schema Don’t box yourself into a corner with the data schema Bandwidth efficiency important Lower the deployment bar This is a well-trod space LDAP, ACAP, SNMP, relational DB cover related spaces, none successfully deployed to broad end client bases

25 XCAP Architecture Same as previous pictures
Network App Same as previous pictures Scope limited to client to XCAP server Access from Network App could be XCAP Acts as a client There may be no network app XCAP server is repository for client data Not Standardized Not Standardized XCAP Server XCAP Client

26 The Big “Aha” XCAP is about clients getting, deleting and putting pieces of hierarchically organized data Ideally XCAP should leverage technologies widely found in phones, PCs and other client devices XCAP can just BE HTTP, by defining the URI hierarchy to extend into “web documents” HTTP URIs can represent any resource Don’t need to exist on a disk Interpretation is up to the server XCAP defines that interpretation

27 HTTP in Brief Clients invoke methods on server
GET – retrieve content PUT – place content POST – pass data to a process HEAD – get meta-data, not content OPTIONS – query server for capabilities DELETE – remove a resource from a server Requests and responses contain bodies

28 Fetch a document GET http://server.com/dir/foo HTTP/1.1 <foo>
<bar attr=“1”>Hi</bar> <bar attr=“2” bool=“y”>How</bar> <movie stuff=“LOTR”>Are</bar> </foo> HTTP/ OK Content-Type: application/xml Content-Length: … <foo> <bar attr=“1”>Hi</bar> <bar attr=“2” bool=“y”>How</bar> <movie stuff=“LOTR”>Are</bar> </foo>

29 XCAP Scope Application Usages Naming convention for URIs
Details how you use XCAP for a new app (i.e., CPCP) Server assigned data Naming convention for URIs Document selector – picks the “XML Document” based on a defined document hierarchy Component selector – picks an element or attribute within the document Using GET, PUT and DELETE for management of elements and attributes Error content Extensibility of data Etag advice

30 Application Usage Defines what an application needs to do to be used with XCAP Define an Application Unique ID Define the XML Schema for the data Define data semantics Specify naming conventions – binding between application and XCAP Data interdependencies (aka server computed data) Authorization policies

31 AUID Unique Identifier for each application Two sub-namespaces
IETF tree: tokens in RFC documents IANA Registry Vendor tree: proprietary data Start with reverse DNS name of enterprise Examples IETF Tree “resource-lists” draft-ietf-simple-xcap-list-usage “pidf-manipulation” draft-isomaki-simple-xcap-pidf-manipulation-usage-00 “rules” draft-rosenberg-simple-rules Vendor Tree “com.example.customer-list”

32 AUID Grammar AUID = global-auid / vendor-auid global-auid = auid
auid = alphanum / mark vendor-auid = rev-hostname "." auid rev-hostname = toplabel *( "." domainlabel ) domainlabel = alphanum / alphanum *( alphanum / "-" ) alphanum toplabel = ALPHA / ALPHA *( alphanum / "-" ) alphanum

33 Naming Conventions An app will have “hooks” into XCAP
Points of operation of application when XCAP is used Need to define how that is done Example: Presence List Fetch document whose uri attribute of <resource-list> is equal to request URI of SUBSCRIBE Example: Authorization Fetch authorization policy documents underneath where username identifies the presentity

34 Data Interdependencies
In many cases a user defines all of their own data PIDF manipulation usage Authorization policies In some cases a few pieces of it are “filled in” by the server Resource list URIs for lists – need to be unique, can be server assigned Client can also define them Application usage specifies what pieces server fills in, and how

35 Modeling Server Computed Data
Think of the application usage as a client of XCAP Handset puts a new resource list, URI not present (1) Application learns of change (4) Acting as a client, application modifies data, setting URI (5) This is a model, not an implementation requirement Impacts Etag usage (later) Handset Application XCAP Server Database (1) PUT Resource List (2) 200 OK (3) store (4) Data Change (5) PUT (set URI) (6) 200 OK (7) store

36 Authorization Policies
Who is allowed to access (R/W) XCAP data? Application specific Policies are specified by application usage XCAP defines a “default” A user can read and write their own data A user can only access their own data Global data is readable by everyone, writeable by no one except privileged users

37 Definition Example Basic address book from before
Would author an RFC structured as follows

38 Document Contents AUID XML Schema Naming Conventions
Want this to be global Pick an appropriate AUID address-book Add an IANA Considerations section registering the AUID XML Schema Include it IANA registry for schema and namespace Naming Conventions No server app No naming conventions No data interdependencies Default authorization policy

39 Semantics An address book is a series of <entry> elements
Each <entry> is information about an entry in the address book It has a <name>, which is the use persons first and last name It has an < > element, which contains the address of the person It has a <postal> element that has the postal address

40 The Document Hierarchy
XCAP defines URIs as two parts Document selector – chooses the XML document Node selector – chooses the XML component (element, attribute) XPath subset discussed previously XML documents organized into a mandatory hierarchy Borrows from ACAP concepts

41 Hierarchy Structure Top is the Root Services URI Next is the AUID
Identifies start of XCAP tree Next is the AUID Next is “users” or “global” “users” are for per-user documents “global” are for data that is not user specific – for reading by all users of the app Within users, next is username Underneath username is anything Eventually leads to document

42 The Hierarchy Root services AUID 1 AUID 2 users global petri hiroshi
doc1 dir1

43 Example 1 adbook1 <?xml version="1.0" encoding="UTF-8"?> <address-book> <!—This guy is a bozo -- <entry> <name>Jonathan Rosenberg</name> <postal> <street paved=“true”>600 Lanidex Pl</street> <city>Parsippany</city> <state>NJ</state> <country>USA</country> </postal> <ietf-participant/> </entry> </address-book>

44 Client Operations Retrieving Deleting Modifying Adding Document
Element Attribute Deleting Modifying Document Element Attribute Adding KEY CONSTRAINT Can only affect one element, attribute or document at a time

45 Fetching a Document GET HTTP/1.1 adbook1 <?xml version="1.0" encoding="UTF-8"?> <address-book> <!—This guy is a bozo -- <entry> <name>Jonathan Rosenberg</name> <postal> <street paved=“true”>600 Lanidex Pl</street> <city>Parsippany</city> <state>NJ</state> <country>USA</country> </postal> <ietf-participant/> </entry> </address-book> HTTP/ OK Content-Type: application/adbook+xml Content-Length: … <?xml version="1.0" encoding="UTF-8"?> <address-book> <!—This guy is a bozo -- <entry> <name>Jonathan Rosenberg</name> <postal> <street paved=“true”>600 Lanidex Pl</street> <city>Parsippany</city> <state>NJ</state> <country>USA</country> </postal> <ietf-participant/> </entry> </address-book>

46 Fetching an Element GET address-book/entry/name HTTP/1.1 adbook1 <?xml version="1.0" encoding="UTF-8"?> <address-book> <!—This guy is a bozo -- <entry> <name>Jonathan Rosenberg</name> <postal> <street paved=“true”>600 Lanidex Pl</street> <city>Parsippany</city> <state>NJ</state> <country>USA</country> </postal> <ietf-participant/> </entry> </address-book> HTTP/ OK Content-Type: application/xml-fragment-body Content-Length: … <name>Jonathan Rosenberg</name>

47 Fetching an Attribute GET HTTP/1.1 adbook1 <?xml version="1.0" encoding="UTF-8"?> <address-book> <!—This guy is a bozo -- <entry> <name>Jonathan Rosenberg</name> <postal> <street paved=“true”>600 Lanidex Pl</street> <city>Parsippany</city> <state>NJ</state> <country>USA</country> </postal> <ietf-participant/> </entry> </address-book> HTTP/ OK Content-Type: application/xml-attribute-value Content-Length: … true

48 Delete a Document DELETE HTTP/1.1 adbook1 <?xml version="1.0" encoding="UTF-8"?> <address-book> <!—This guy is a bozo -- <entry> <name>Jonathan Rosenberg</name> <postal> <street paved=“true”>600 Lanidex Pl</street> <city>Parsippany</city> <state>NJ</state> <country>USA</country> </postal> <ietf-participant/> </entry> </address-book> HTTP/ OK NULL

49 Deleting an Element adbook1
<?xml version="1.0" encoding="UTF-8"?> <address-book> <!—This guy is a bozo -- <entry> <name>Jonathan Rosenberg</name> <postal> <street paved=“true”>600 Lanidex Pl</street> <city>Parsippany</city> <state>NJ</state> <country>USA</country> </postal> <ietf-participant/> </entry> </address-book> DELETE address-book/entry/name/ HTTP/1.1 <?xml version="1.0" encoding="UTF-8"?> <address-book> <!—This guy is a bozo -- <entry> <name>Jonathan Rosenberg</name> <postal> <street paved=“true”>600 Lanidex Pl</street> <city>Parsippany</city> <state>NJ</state> <country>USA</country> </postal> <ietf-participant/> </entry> </address-book> HTTP/ OK

50 Deleting an Attribute adbook1
<?xml version="1.0" encoding="UTF-8"?> <address-book> <!—This guy is a bozo -- <entry> <name>Jonathan Rosenberg</name> <postal> <street paved=“true”>600 Lanidex Pl</street> <city>Parsippany</city> <state>NJ</state> <country>USA</country> </postal> <ietf-participant/> </entry> </address-book> DELETE HTTP/1.1 <?xml version="1.0" encoding="UTF-8"?> <address-book> <!—This guy is a bozo -- <entry> <name>Jonathan Rosenberg</name> <postal> <street>600 Lanidex Pl</street> <city>Parsippany</city> <state>NJ</state> <country>USA</country> </postal> <ietf-participant/> </entry> </address-book> HTTP/ OK

51 Modify vs. Add Modify and Add look the same Behavior depends on URI
PUT Request Body contains content Behavior depends on URI Server checks if resource exist URI resolves to an existing doc, element in a doc, or attribute in an element If not, the operation is add New content is added such that URI now resolves to the content in the body Schema constraints are obeyed Otherwise inserted after all siblings If so, the operation is modify New content replaces the content selected by the URI

52 Insert an Element adbook1
<?xml version="1.0" encoding="UTF-8"?> <address-book> <!—This guy is a bozo -- <entry> <name>Jonathan Rosenberg</name> <postal> <street paved=“true”>600 Lanidex Pl</street> <city>Parsippany</city> <state>NJ</state> <country>USA</country> </postal> <ietf-participant/> </entry> </address-book> PUT address-book/entry/phone HTTP/1.1 Content-Type: application/xml-fragment-body <phone> </phone> <?xml version="1.0" encoding="UTF-8"?> <address-book> <!—This guy is a bozo -- <entry> <name>Jonathan Rosenberg</name> <phone> </phone> <postal> <street paved=“true”>600 Lanidex Pl</street> <city>Parsippany</city> <state>NJ</state> <country>USA</country> </postal> <ietf-participant/> </entry> </address-book> HTTP/ OK

53 Modify an Element adbook1
<?xml version="1.0" encoding="UTF-8"?> <address-book> <!—This guy is a bozo -- <entry> <name>Jonathan Rosenberg</name> <postal> <street paved=“true”>600 Lanidex Pl</street> <city>Parsippany</city> <state>NJ</state> <country>USA</country> </postal> <ietf-participant/> </entry> </address-book> PUT address-book/entry/name HTTP/1.1 Content-Type: application/xml-fragment-body <name>Jonathan D. Rosenberg</name> <?xml version="1.0" encoding="UTF-8"?> <address-book> <!—This guy is a bozo -- <entry> <name>Jonathan D. Rosenberg</name> <postal> <street paved=“true”>600 Lanidex Pl</street> <city>Parsippany</city> <state>NJ</state> <country>USA</country> </postal> <ietf-participant/> </entry> </address-book> HTTP/ OK

54 Server Error Handling Server error handling is specified in HTTP specification Most XCAP-specific cases are details within 404 or 409 409 (Conflict) The request could not be completed due to a conflict with the current state of the resource. 404 (Not Found) The server has not found anything matching the Request-URI. XCAP Specific error cases Result of operation results an a document that is not well-formed or valid (409) Resource identified in a request corresponds to multiple elements or attributes (409) Application usage not understood (409) Document, element or attribute does not exist (404) Client provided data that violates a uniqueness requirement (409) Request did not contain valid xml-frag-body (409?)

55 Conveying Conflict Details
HTTP recommends including a 409 body detailing problem so client can retry XCAP defines an XML body format for response application/xcap-error+xml MIME type Root element <xcap-error> Child is specific to the error Detailed error information can be dependent on the error Defined errors match ones on previous slide

56 URI Exists Error Client attempts to set a URI with a uniqueness constraint, and the value exists already Happens in resource lists Server error response indicates URI(s) which had this problem Optional suggested alternates <?xml version="1.0" encoding="UTF-8"?> <xcap-error xmlns="urn:ietf:params:xml:ns:xcap-error"> <uri-exists> <exists </exists> </uri-exists> </xcap-error>

57 Handling Multiple Writers
Synchronization problems occur when multiple clients can manipulate the same document Especially true when a client needs to do multiple HTTP operations to affect a change XCAP provides no lock But we want to detect this condition and recover Common problem User A User B XCAP Server (1) PUT (Modify Buddy 1) (2) 200 OK (3) PUT (Modify Buddy 1) (4) 200 OK B wins (5) DELETE (attribute removed by A) (6) 409

58 Solution: Etags ETag from HTTP What does this mean?
Entity tags are used for comparing two or more entities from the same requested resource. An entity tag MUST be unique across all versions of all entities associated with a particular resource. What does this mean? ETag is a version identifier for a resource Server assigns the etag It changes every time the resource changes

59 How are they used? HTTP defines several conditional headers
If-Match: only process this request if the entity tag matches that held by the server If-None-Match: only process this request if the entity tag does not match If-Range: asks for the byte range that has changed Server returns 412 if condition fails

60 Example Revisited User A has version ABC
Adds buddy, adds If-Match: ABC Buddy added, new version DEF User B also has version ABC Tries to modify it, but it fails B can now fetch it and make its diff against the current version User A User B XCAP Server (1) PUT (Modify Buddy 1) Etag ABC (2) 200 OK Etag DEF (3) PUT (Modify Buddy 1) ABC (4) 412

61 Data Extensibility XCAP servers MUST understand the application usages they manage They don’t need to understand any namespaces but the root ones Document extensions don’t need to be understood Sometimes, an extension requires the server to understand Setting a URI Guaranteeing Uniqueness

62 Current Solution Defines a “mandatory-ns” element
This attribute is present as a child of the root element in any document Indicates what namespaces are mandatory <?xml version="1.0" encoding="UTF-8"?> <address-book xmlns:conf=“urn:ietf:2233”> <mandatory-ns> <ns>urn:ietf:2233</ns> </mandatory-ns> <!—This guy is a bozo --> <entry> <name>Jonathan Rosenberg</name> <postal> <street paved=“true”>600 Lanidex Pl</street> <city>Parsippany</city> <state>NJ</state> <country>USA</country> </postal> <conference-uri/> <ietf-participant/> </entry> </address-book>

63 Presence Authorization
Specified as a ruleset Each ruleset is a series of rules Each rule has three parts Condition – does this rule apply? Action – what do you do if it does? Transformation – how do you restrict the data seen by a requestor?

64 Permission Model Each action or transformation is called a permission
A permission is a positive grant of information There can never be negative grants, i.e., “don’t send information X” If there is no permission for something, you get nothing Implication is that the system is privacy safe

65 Privacy Safe If a server doesn’t understand a permission, less information is sent than desired, never more If a server cannot obtain a rule from a remote source, less information is sent than desired, never more No network failures or other transient problems can result in more information being sent than is desired

66 Common Policy draft-ietf-geopriv-common-policy Defines framework
Defines common elements in all systems <identity> - condition matching based on user identity <sphere> - condition based on your presence status <validity> - time range

67 Current Presence Authorization Elements
Extends the set defined in common-policy with presence-specific data New conditions <anonymous> - is the subscription anonymous Actions <accept-subscription> - accept the presence subscription <provide-presence> - polite blocking or not Transformations <show-namespace> - provide elements from a specific namespace <show-tuple> - provide elements from specified tuples <show-element> - provide elements with a specific name

68 <?xml version="1.0" encoding="UTF-8"?>
<cr:ruleset xmlns="urn:ietf:params:xml:ns:pres-rules" xmlns:cr="urn:ietf:params:xml:ns:common-policy" xmlns:rpid="urn:ietf:params:xml:ns:rpid" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"> <cr:rule id="1"> <cr:conditions> <cr:identity> </cr:identity> </cr:conditions> <cr:actions> <accept-subscription>true</accept-subscription> <provide-presence>true</provide-presence> </cr:actions> <cr:transformations> <show-namespace> <ns>urn:ietf:params:xml:ns:rpid</ns> </show-namespace> <show-element> <basic-elements/> <el>rpid:placetype</el> </show-element> </cr:transformations> </cr:rule> </cr:ruleset>


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