CDDLM XML-CDL

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CDDLM XML-CDL

Jun TatemuraNEC Laboratories Amercia

GGF10, March 2004

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Background: Components and Component Services How applications are deployed on top of

infrastructure

LinuxComponent

ServiceService

Requester

applicationApplication

serverComponent

ServiceService

Requester

J2EE app

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User (who deploys)

CDL’s Role in Deployment Example: Three-tier web applications

Resource provider

Appserver

Appserver

Appserver

DBserver

DBserver

DBserver

Webserver

Webserver

WebserverComponent

service

Componentservice

Componentservice

CDLTemplateCDL

Template

CDLTemplate

ApplicationWrapper

Provider (developer)CDL TemplateFor 3tier app

CDLFor a specificdeployment

request

ResourceBroker

Info from agreement

CDDLMprocessor

BasicService

+

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Issues Overview [1] Attribute set description model [2] Component description model [3] Lifecycle management model [4] Dependencies and assertions [1-4] Relationship with SmartFrog

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CDL Top-Level Structure Divided into sections (similar to WSDL)

Cf. SmartFrog has a uniform language structure and utilizes predefined names and frameworks (e.g., sfConfig, Prim)

Configuration on a system can be described in multiple CDL files

<import> and <include>

<cdl targetNamespace=“xsd:anyURI”> <types …/>?  <configuration …/>?  <system …/>?  <services …/>? </cdl>

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Import and Include Similar to XML Schema <import namespace=“xsd:anyURI” location=“xsd:anyURI” />

Import of external namespaces <include location=“xsd:anyURI” />

Inclusion of XML Data Similar to SmartFrog’s #include but may be more r

estrictive due to validity as XML data

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Issue 1: Attribute Set Description Model

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Attribute Sets Configuration is a set of attribute-value pairs Inheritance: the “extends” operation (from SmartFrog) for extensibility of co

nfiguration Every attribute set can be referred to with a QName

extendsoverride additionreuse

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Using QName for Attribute Set Name Namespace realizes a globally unique

reference to specify an attribute set

<cdl targetNamespace=“uri1”><attributeSet name=“abc” .../></cdl><cdl xmlns:tmpl=“uri1”>

<attributeSet name=“myabc” extends=“tmpl:abc” .../></cdl>

A template CDL providedby the application provider

CDL specified by the applicationuser

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Two Design Alternativesof Attribute Description [Alt-1] CDL specific attribute e

lements (current draft)<cdl:attributeSet cdl:name=“apache” cdl:extends=“ex:httpd”> <cdl:attribute> <cdl:name>hostname </cdl:name> <cdl:value> example.com </cdl:value> </cdl:attribute></cdl:attributeSet>

[Alt-2] Configuration specific schema

<tns:apache cdl:name=“apache” cdl:extends=“ex:httpd”> <tns:hostname cdl:use=“…” …> example.com </tns:hostname></tns:apache>

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[Alt-1] Attribute Sets <attributeSet> element

@name defines QName of this set @extends specifies a prototype set

<attributeSet name=“xsd:NCName” extends=“xsd:QName”?> <attribute …/>*</attributeSet>

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[Alt-1] Attributes A pair of name and value Augmented by <type>, <lifetime>, <use>, etc.

type: type definition (XML Schema) lifetime: deployment | runtime | dynamic use: required | optional | readonly -- discussed later as another issue

<attribute> <name>host</name> <type>xns:ipAddress</type> <lifetime>deployment</lifetime> <use>required</use> <value>15.144.56.243</value></attribute>

<attribute> <name>xsd:string</name> <type/>? <lifetime/>? <use/>? <value/>?</attribute>

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[Alt-1] Nested Attribute Sets An attribute can have an attribute set as its value Nesting of attribute sets is flattened and linked with r

eferences (QNames)

<attribute> <name>database-server</name> <type>cdl:refToAttributeSet</type> <lifetime>deployment</lifetime> <use>required</use> <value>tns:database</value></attribute>

<attributeSet name=“database” extends=“oracle” > <attribute .../> ...</attributeSet>

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[Alt-1] Reference to Attribute An attribute is identified with the QName of an attribut

e set + the name (string) of an attribute This is one reason why attribute sets are flattened

<reference><attributeSet>xsd:QName</attributeSet>?<attributeName>xsd:string</attributeName></reference>

(alternative expression)<reference set=“xsd:QName”?>xsd:string</reference>

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[Alt-2] Fully-bound Configuration Documents After references are resolved and values are fixed, a document becomes

a simple and natural XML data based on application-specific schema Similar to WS-ResourceProperties

<apache cdl:name=“xsd:NCName”> <MaxClients>150</MaxClients> <HostName>example.com</HostName> …</apache><apache cdl:name=“xsd:NCName”

　　　　　　 cdl:extends=“xsd:QName”> <HostName /> …</apache>

resolution

Schema for a particular

configuration document

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[Alt-2] CDL Functionalities Functionalities same as Alt-1 are achieved

with attributes (@name, @extends,…)

<apache cdl:name=“myapacheconfig”　　　　　　 cdl:extends=“tmpl:apachetmpl”> <HostName>myuri.com</HostName> …</apache>

<apache cdl:name=“apachetmpl”　　　　　　 cdl:extends=“x:httpd”> <MaxClients>150</MaxClients> <HostName cdl:lifetime=“deployment” cdl:use=“optional” /> …</apache>

extends

A template CDL providedby the application provider

CDL specified by the applicationuser

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[Alt-2] Drawback: Schema Definition Is Mandatory Schema is required to assure a valid CDL

document is also a valid XML document

<apache cdl:name=“myapache” …/>

<apache cdl:name=“template” …/>

<httpd cdl:name=“template” …/>

Schema for generic http

d

Schema for vendor specific h

ttpd

CDL for generichttpd template

CDL for vendor specifichttpd template

CDL for user deployment

Redefinitionof schema

New elements

added

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[Alt-2] Nested Attribute Sets Nested structure can be applied Better readability More powerful inheritance and reference models

<webapp cdl:name=“mywebapp”　　　　　　 cdl:extends=“tmpl:webapp”> <webtier> <MaxClients>100</MaxClients> </webtier> <apptier> <MaxThreads>100</MaxThreads> </apptier> <dbtier> <MaxConnection>150</MaxConnection> </dbtier> …</webapp>

<reference root=“xsd:QName”> xpath</reference>

extends

includes

Inheritance (recursive)

Reference (QName+Xpath)

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Pros and Cons [Alt-1] CDL specific attri

bute elements Pros:

Schema is optional Semantically similar to S

martFrog Cons:

Bad readability Configuration data must b

e given in a different style from other WS-RF based resources

[Alt-2] Configuration specific schema

Pros: Readability Syntactically similar to S

martFrog Better match with WS-RF Xpath reference model

Dependencies and assertions can use XPath

Cons: Schema is required

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Issue 2: Component (Wrapper) Model

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Component Model A system is a tree which leafs are components A component refers to an attribute set A component is deployed through a Component Service

(CDDLM wrapper)

<system>

<system>

<component><component>

<component>

ComponentService

endpoint WS-Resource

<configuration>

<attributeSet> <attributeSet>

ComponentService


ComponentService


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Binding to Component Service Endpoints A <services> element binds components to

component service endpoints Similar definition structure to WSDL

<system>

<system>

<component><component>

<component>

ComponentService


<services><service component=“xsd:QName”>wsa:EndpointReference</service>…</services>

Typically given after resource assignment agreement

Typically given before resource assignment agreement

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Component Model Discussion Component Service endpoint may be either W

S-RF-based or OGSI-based Nice to have a transparent description in CDL WS-Addressing’s EndPointReference may be used

Do we standardize: How to identify content of application (e.g., URL, p

ath within an archive file) How to transfer content of application -- May be component service specific

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Issue 3: Lifecycle Management Model

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Lifecycle Management in CDDLM CDDLM Processor must manage deployment

lifecycle of multiple components

ComponentService

endpoint

ComponentService

endpoint

ComponentService

endpoint

CDDLMProcessor

CDDLM-Serviceendpoint

CDDLM Client(e.g.,

Job Manager)

•deploy•start•stop•undeploy•get/set•getStatus

•deploy•start•stop•undeploy•get/set•getStatus

Consistency among components should be maintained

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Constraints on Attributes For better management of consistency Lifetime: deployment|runtime|dynamic

When value should be fixed Use: required|optional|readonly

Whether value should be given Read-only value is assigned only by Component services (only get

operation is valid on this attribute) (e.g., a port number may be dynamically assigned)

Lifetime must be specified when use is specified Type: QName of schema [Alt-1] SmartFrog has only deployment and dynamic (LAZY) lifeti

me. CDDLM does not know when a lazy value is resolved.

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Lifecycle Dependency in a System Restriction on the order of lifecycle man

agement operations <deployAfter> <startAfter>

If lifecycle dependency is only from data dependency, we may not need these notations (order can be inferred from data dependency)

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Issue 4: Dependencies and Assertions

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Dependencies An attribute value is derived from other

attribute values

<assign><to><reference …/></to><from>{<reference …/>|<expression …/>|<value …/>}</from></assign>

<attribute><name>xsd:string</name>{<reference …/>|<expression …/>|<value …/>}?</attribute>

and/or

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Assertions An assertion specifies a condition which must be satisfi

ed by given attribute values An assertion has QName so that it can be overridden

<assert name=“xsd:NCName” language=“xsd:anyURI”?> xsd:any</assert>

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Issues on Dependencies and Assertions Expression languages?

Specified with URI There should be one normative expression We may let Xpath 1.0 be the default normative exp

ression. http://www.w3.org/TR/1999/REC-xpath-19991116 Later we may add Xpath 2.0 as an alternative URI

Where to place Within an attribute set Outside of attribute sets

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Example of XPath-based Expression Any attribute value can be assigned to xpath VariableR

eference ($QName) by using <reference> and <let>

<cdl:expression><xp:root><cdl:reference …/></xp:root>?<xp:let name=“NCName”> * <cdl:reference …/></xp:let><xp:return>xpath</xp:return></cdl:expression>

variable bindings

the context node

xpath pattern

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Relationship with Attribute Description Alternatives If we take [Alt-2] for attribute description, Xpath-ba

sed dependencies and assertion would be more powerful and intuitive

<apache cdl:name=“apachetmpl”> <MaxClients>150</MaxClients> <HostName/> … <cdl:assert> boolean(MaxClients > 0) </cdl:assert></apache>

The parent of <assert> (i.e., <apache>) is regarded as the context node o

f XPath

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Action Items Completion of the first draft by GGF11 More discussion on Issues Evaluation on design alternatives

based on examples (from our use cases)

CDDLM-Services “basic” services and component services

LM requirements Partial (re) deployment, etc.

CDDLM XML-CDL

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