Approaches to the Integration of Distributed and .ppt
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1、1,Approaches to the Integration of Distributed and Heterogeneous Data Resources,Ahmet Sayar Indiana University Computer Science Department,2,Motivation,Integrating data from multiple data sourcesDistributed query and transactions of data.Definitions and adoptions of data, metadata and their storages
2、.Accessing the data seamlessly.Transparency, support for heterogeneity, extensibility and scalability.,3,Outline,Data Integration Approaches Application Specific Solutions Application-Integration Framework ASIS (Application Specific Information System) Database Federation Ogsa-DAI (Ogsa-Data Access
3、and Integration) Compare ASIS with Ogsa-DAI Digital Libraries SRB (Storage Resource Broker) Sompels Digital Library Approach Compare ASIS with SRB and Sompels DL,4,Application Specific Solutions,The most common means of data integration Expensive -in terms of time and skills Developing and using req
4、uires deep system knowledge Better results for special-purpose applications Fragile Changes to the underlying sources may easily break the application Hard to extend A new data source requires new code to be written,5,Outline,Data Integration Approaches Application Specific Solutions Application-Int
5、egration Framework ASIS Database Federation Ogsa-DAI Compare ASIS with Ogsa-DAI Digital Libraries SRB Sompels DL Compare ASIS with SRB and Sompels DL,6,Application-Integration Framework,It can also be called component-based framework Such as CORBA or Filters with common interfaces Not necessarily ad
6、dress data integration issues Based on common data model (such as CML and GML) With adaptors, if the source change the adaptor may have to change, but application may never see it. Adding a new source is easy a new adaptor may need to be written. The adaptor may already be exist online. No need to d
7、etailed system knowledge Ex. ASIS - OGC GIS Application Integration Framework,7,ASIS (1),Enables inter-service communication through well-defined service interfaces, message formats and capabilities metadata. Data model is ASL (Application Specific Lang.) Metadata model is capability document Data a
8、nd metadata have common predefined schema Components are Filter Services Web Services, comon service interfaces defined in WSDL Information/data services enabling distributed access, querying and transformation through their predictable input/output interfaces. Chainable, located, and capable of upd
9、ating their metadata manually or dynamically,8,ASIS (2),Data and data storage model Any data can be integrated into the system after transforming to ASL. Heterogeneity is handled at the end-Filters with adaptors. ASL is community-accepted application specific language GML (Geographic Markup Lang.) i
10、n GIS applications CML (Chemistry Markup Lang.) in Chemistry applications Filters common service interfaces getCapabilities, getData, getFeatureInfo. Requests to Filters interfaces getCapabilitiesReq, getDataReq, getFeatureInfoReq Expected return types are defined in Filters capability metadata,9,AS
11、IS (3),Metadata and Metadata storage model: Data integration is done through Filters capability metadata Metadata is stored in local Filters file system as a flat file. Capability: Inspired from OGC WMS capability specification. Look like Dublin Core format. Capability like structure is also used in
12、 Gannons approach (XPOLA), for Grid services security issues. Describes dynamic Web/Grid resources. Updated manually or dynamically. Consists of descriptor, service and provider metadata Inter-service communication is achieved without a third-party. Enables chain of Filters.,10,ASIS (4) Data Access
13、and Filter Chaining,F1,F3,F2,F4,Fault,State Boundary,Earth,Each Filter is capable of acting as both a server and a client Capability integration is done through “getCapability” service interface Requests for common service interfaces are created in accordance with predefined XML schema,Fault,11,Outl
14、ine,Data Integration Approaches Application Specific Solutions Application-Integration Framework ASIS Database Federation Ogsa-DAI Compare ASIS with Ogsa-DAI Digital Libraries SRB Sompels DL Compare ASIS with SRB and Sompels DL,12,Database Federation,Middleware consisting of database management syst
15、em Uniform access to number of heterogeneous data sources Provides query language used to combine, contrast, analyze and manipulate the data Data integration is done through Database integration. Combine data from multiple sources in a single SQL statement query recreation. Ex. Ogsa-DAI (Open Grid S
16、ervice Architecture Data Access and Integration),13,Ogsa-DAI (1),Provides common Java API for accessing and integrating data resources such relational and XML databases, and files- in Grid environment Specifically designed for OGSA architecture SQL queries on relational resources and XPath statement
17、s on XML collections Provides data pipelining (similar to Filter chaining) via an XML document called “perform” document. Allows developers to easily add or extend functionality within Ogsa-DAI, “activity” document.,14,Ogsa-DAI (2),Data and storage model : Any data stored in XML or relational databa
18、ses, files No common data model Data is provided through GDS (Grid Data Services) Uses Ogsa-DQP (Distributed Query Processor) to coordinate to access to multiple data services The enactment engine is the core of Ogsa-DAI. Orchestrate running of the perform document Information in perform document in
19、cludes: The list of activities and their XML schemas and implementation classes. The list of role mappers and details The info about data resource,15,Ogsa-DAI (3),Metadata storage model: Metadata is kept in Catalog Service (MCS) MCS enables attribute-based querying Metadata is for the datasets, data
20、 can be anything (binary, text ) Data integration is done through XML based activity file mixing activities (in SQL queries) and metadata Simple data access scenario A client contacts a DAISGR first to locate the GDSFs. Accesses suitable GDSFs directly to find out more about their properties and the
21、 data resources they represent. Asks GDSF to instantiate a GDS Accesses resource by sending the GDS the GDS-Perform doc.,16,Ogsa-DAI (4),Metadata model: No common schema for metadata like capability Defines Metadata for the datasets No schema in XML Stored in Database tables as attributes Defines Me
22、tadata for the Database system to enable querying and defining activities Schema in XML (mcsActivity.xsd schema file) Kept as XML file in the file system (mcsActivity.xml),17,ASIS vs. Ogsa-DAI,Ogsa-DAI does not define metadata and data in XML schema. Metadata is mixed with Database schema. ASIS has
23、predefined data and metadata models. Ogsa-DAI uses any data, and they have predefined Database schema to enable querying and accessing data. ASISs data integration is on demand and based on capability federation. Instead, Ogsa-DAIs data integration is coded in XML struc perform and activity document
24、s. Ogsa-DAI has central (MCS), ASIS has distributed metadata approach. Both system are based on Web Services. Ogsa-DAI uses GridFTP, and ASIS uses NaradaBrokering for the performance issues in data transfers.,18,Outline,Data Integration Approaches Application Specific Solutions Application-Integrati
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