1

The MOCHA ProjectThe MOCHA Project

• Goals:– Transparent access to distributed data sources– Scaleable middleware architecture– Automatic deployment of code (Plug-N-Play)– On-site processing and “filtering” of data – Reduction of data movement over Internet– Built upon Java and XML standards

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MOCHA 3 -Tier ArchitectureMOCHA 3 -Tier Architecture

• Clients– Web-based (applets)

• Query Processing Coordinator – Metadata for schema translation– Java Code Repository (types and methods)

• Data Access Provider– Data translation– Data filtering

• Data Server– Repository of metadata and data products

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Plug-N-Play Code DeploymentPlug-N-Play Code Deployment

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Client

Oracle Informix

DAP DAPQPC

CodeRepository

Catalog

Internet

Virginia

MarylandVirginiaTexas

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QQQQ

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Plug-N-Play Code DeploymentPlug-N-Play Code Deployment

Select location, Composite(image)From RastersWhere week BETWEEN t1 and t2Group By location

Client

Oracle Informix

DAP DAPQPC

CodeRepository

Internet

Virginia

MarylandVirginiaTexas

Catalog200MB

tuples

100MB

tuples

results

200KB

results

150KB

results

150KB

results

200KBresults

150KB

results

200KB

results

350KB

results

350KB

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MOCHA FeaturesMOCHA Features

• Uniform access to distributed data– Integrated schema for multiple sites

• Platform independent solution– Java and XML

• Fully extensible – User-defined types and methods (MOCHLETS)

• Access data in their existing formats– On-site retrieval and processing of live data

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MOCHA FeaturesMOCHA Features

• Automatic code deployment (Plug-N-Play)– Easy to administer– Easy to extend and upgrade

• “Light-weight” data access layer– Easy to customize, install, and enhance

• XML-based metadata for– System catalog– Data products

• Efficient Query Processing – Minimize data movement over Internet

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Advantages Over Previous SolutionsAdvantages Over Previous Solutions

• Web-based Thin Clients– Single point of access to the system: QPC

• Easy and inexpensive to configure– Users need not be aware of low-level details (data

sites, data servers, schemas, …)

• Unlimited Extensibility– SQL and XML query services (no inefficient scripting)– Customizable types and user-defined methods

(MOCHLETS)

• Scaleable– Easy to add new services, sites, code, and clients

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Project StatusProject Status

• Operational System– Multi-threaded QPC with catalog and code repository– Relational and XML DAPs– Data Sites

• 3 servers with relational DAPs• 1 high-performance SP2-HPSS data repository

• Demonstrated at ACM SIGMOD 2000 Conf.– Access TM, AVHRR and GIS Data Products– Web demo: http://mocha.umiacs.umd.edu

• Future work– Deployment on ESIP Federation