CDDLM Configuration Description Language (CDL).ppt

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1、CDDLM Configuration Description Language (CDL),Jun Tatemura NEC Laboratories America GGF13, March 15 2005,CDL Core concept overview CDL FAQ from draft reviews Essential questions regarding CDL design philosophy,User (who deploys),Use of CDL in Deployment,Example: Three-tier web applications,Resource

2、 Broker,CDDLM XML-based CDL,Configuration: Property L80CDL Notations cdl:extends inheritance of prototype cdl:ref value reference cdl:type data type annotation cdl:lazy lazy (runtime) value resolution,Prototype References,cdl:extends=xsd:QName,808080200,,8080200 ,Value References,cdl:ref=cdl:pathTyp

3、e,Schema Annotations,cdl:type cdl:use,80 ,Laziness Annotation,cdl:lazy=“xsd:boolean”,Lazy Property (provide side annotation),Lazy Reference (consumer side annotation),CDL Document,cdl import types configuration system,?*?*?*?* ,CDL FAQ,Inheritance (prototype references) Value references Data Types,I

4、nheritance Q1,Why Inheritance? Isnt inheritance just a feature of front-end systems? CDDLM could receive a CDL document after inheritance resolved.,Inheritance A1,A Inheritance is used between component providers and component users. Standardization is thus required. Component description from a pro

5、vider describes properties that are supported as a prototype Names, types, default values, optionality, laziness A component provider Inherits the prototype to give property values, composite structures of components Note: CDL provides declarative description through prototype-based inheritance + im

6、mutable property lists,Inheritance Q2,Why not inherit a deep tree? Prototype resolution only inherits immediate children. We may want to overload data within a deep structure.,a,c,f,a,b,e,c,d,f,100,10,30,1,20,extends,a,b,e,c,d,f,100,30,1,20,Inheritance A2 (1),It will be difficult to override a prope

7、rty with structured data,a,c,g,a,b,e,c,d,f,100,10,30,1,20,extends,h,200,?,Inheritance A2 (2),Parameterization,localhostlocalhost ,list2,list1,Inheritance Q3,Why inheritance is defined on an ordered list What makes a difference between property set inheritance and property list inheritance,extends,In

8、heritance A3,A The CDDLM Component Model needs an ordered tree A XML is an ordered tree. A user of CDL may want to have ordered property lists (the Component Model is an example) cdl:extends corresponds to xsd:extension of xsd:sequence,Value references Q1,Why do we need cdl:refroot,We may use:,We no

9、w use:,Value references A1,A it will be also complicated when it is combined with prototype resolution Most references will be within a tree (i.e., no need of cdl:refroot),100200 ,200 ,200 ,?,100 ,100 ,Value references Q2,Why lazy references Isnt a lazy property (provider-side annotation) enough? Wh

10、y do we need a consumer-side laziness annotation?,Lazy property,Lazy reference,Value Reference A2,A an example: a reference to a system environment property (e.g., current time). The consumer side wants to control resolution timing,Note: CDL itself does not define “system properties”,Data Types Q1,I

11、s CDL yet another schema language? Are you trying to replace XML Schema?,Data Types A1,CDL is designed to leverage (not replace) XML SchemaHow to achieve schema validation in CDL CDL: Prototype-based inheritance to generate configuration data in a flexible and dynamic manner Challenge: how to make u

12、se of XML Schema to validate dynamically extensible data Note: Schema validation is optional in CDL,Solution: cdl:type Attribute for Type Annotation,cdl:type=“qname” Type specification for property values Source data can be validated with cdl:type Resolved data can be validated with cdl:type (type c

13、heck) and cdl:use (optionality check),Generating XML Schema for Validation,A CDL processor may optionally generate XSDs for unresolved and/or resolved configuration data,CDL,CDL,XSD,CDL processor,CDL,XSD,validates,refers-to,refers-to,Resolution result,XSD for unresolved data (source data),XSD,valida

14、tes,XSD for resolved data (result data),Example of Validation,After reference resolutionv1v3A CDL processor may generate Configuration datav1v3 XSD for the configuration data ,Data types Q2,How to use cdl:types and cdl:import Should data types be defined internally (using cdl:types) or externally (importing with cdl:import)?,. ,Data Types A2,A cdl:type is used when data types are defined within the namespace of the configuration data,Referred to with the same namespace (uri1),