Database Access and Integration Services on the

Database Access and * Integration Services on the Grid Authors: Presented by: N. Paton, M. Atkinson, V. Dialiani, D. Pearson, T. Storey, P. Watson Ariel Cary Florida International University School of Computing and Information Sciences Summer 2006 * http: //www. cs. man. ac. uk/grid-db/papers/dbtf. pdf DAIS Grid

Agenda § Introduction § Scope and Context of Proposal § Proposed Database Services § DS in OGSA § Current DAIS Standards and Systems § Conclusion DAIS Grid 2

Introduction • Grid research generally focus on applications where data is stored in files • DBMS systems have a central role in data organization for numerous applications, e -Science: particle physics (LHC@CERN), earth sciences, bio-informatics • There is a need to interconnect pre-existing and independently operated databases DAIS Grid 3

Introduction (cont) Ÿ This work seeks to encourage the development of standards that can meet those needs. Ÿ A (preliminary) proposal is made for the staged development of a collection of Grid Database Services that allow access to existing, autonomous databases within Grid Ÿ Follows a service-based approach within OGSA framework for DBMS integration DAIS Grid 4

Introduction (cont) Ÿ Services definitions essentially state what functionality is to be supported Ÿ How functionalities are supported may come to be implemented in different ways (performance characteristics, etc. ) DAIS Grid 5

Scope and Context of Proposal DAIS Grid 6

Scope Ÿ The proposal has several characteristics – Independent of any specific Grid toolkit (could skew and restrict it) – It does not propose the development of a new DBMS for the Grid, but wrapping existing systems to a consistent interface and developing distributed managers – Independent of any specific data model or access language DAIS Grid 7

Context Ÿ Relevant terms related to Databases – Database Service is any service that supports a database interface (WSDL) – Service interfaces are abstract and not prescriptive on how they are supported, or the data model that underpins a DBMS – Specific DBMS services could provide access to relational or object DBMS, XML repositories, specialist storage systems … DAIS Grid 8

Context – Grid Database Service (GDS) provides capabilities for querying, updating and evolving a database – The interface also describes: ŸData delivery: transmitting structured data ŸTransactions: coordinating collections of operations ŸDatabase Metadata: accessing information about the data a DB service provides DAIS Grid 9

Proposed Database Services DAIS Grid 10

Database Discovery Ÿ A service provider publishes description (WSDL) of a service to a service registry Ÿ Later consulted by a requestor, and binding created that allow calls to the service Ÿ It is assumed that a registry lookup returns a Grid Service Handle (GSH), globally unique name for a service instance DAIS Grid 11

Database Statements Ÿ Statements allow queries or change operations to be sent to a DBMS Ÿ This implies that the underlying DBMS supports a query or command language, different on every database model Ÿ Thus, it is a point of tension with the proposal being independent of the data model DAIS Grid 12

Database Statements (cont. ) Ÿ The pairs (query. Notation, query), … are introduced to allow flexibility (like MIME types for e-mail attachments) Ÿ For example: – – DAIS Grid query. Notation=“SQL’ 92” query=“Select * from EMP Where Salary>1000” 13

Database Statements (cont. ) Ÿ The final results of an operation are managed via: – – result. Handle: generated dynamically expires: an expiry time up for the result to be claimed Ÿ The optional tx. Handle indicates if the operation is part of a transaction, provided the DBMS supports transactions DAIS Grid 14

Database Statements (cont. ) Ÿ The operations on a GDS will be atomic: – – – Preparation and Validation: consistency check Application: operation is performed Result Delivery: results available to the caller Ÿ Usually involve transfer of large amounts of data which may take long time to execute (prone to interruptions!) Ÿ The implementation of the DBMS service should handle such failures to achieve atomicity DAIS Grid 15

Delivery System Ÿ Means by which (potentially large amounts of) structured data is moved from one locations to one or more others Ÿ Should be considered complementary to protocols such as Grid. FTP, which could be used as a delivery mechanism DAIS Grid 16

Delivery System (cont. ) Ÿ Single data source to be delivered, represented as a URI Ÿ Several destinations represented by URI with delivery mechanisms associated Ÿ The deliver operation initiates delivery of the data from the single source to multiple destinations Ÿ A more elaborated delivery system would include encryption, progress monitoring, etc. DAIS Grid 17

Distributed Transactions Ÿ A minimal transaction interface: performs the role of conferring a guaranteed unique identity on the transaction Ÿ Given a transaction handle, other operations over a database service can be put explicitly within the context of a transaction, using the tx. Handle parameter DAIS Grid 18

Distributed Transactions (cont. ) Ÿ For a transaction to span multiple DBMS services, they must provide operations for use by the transaction manager that is overseeing the distributed transaction Ÿ start. Transaction includes an expires param. to limit the consumption of resources Ÿ prepare. Commit operation can be used by a two-phase commit protocol to ensure that all participating database services commit DAIS Grid 19

Database Metadata Ÿ Metadata that could be useful to have access to includes: – – Content description: DB schema – data model, logical & physical structures, stats (could be obtained from the data dictionary) Capability description: language (query /update operations supported), transactional capabilities, protocols supported Ÿ The metadata should be described in a standard representation, e. g. XML document given by the data service provider DAIS Grid 20

Distributed Query Service Ÿ Query DS 1 (DQS) Ÿ Parsed & optimized Ÿ Sub-queries to relevant DB’s Ÿ Results collected & joined by DQS DAIS Grid 21

Database Services in OGSA DAIS Grid 22

DS in OGSA Ÿ The Open Grid Services Architecture (OGSA) represents an evolution towards a Grid system architecture based on Web services concepts and technologies* Ÿ The described interfaces can be used as the basis of database services through participation in the OGSA Ÿ Thus many features of this architectural framework can be obtained for service creation, authorization, notification, etc. DAIS Grid 23 * http: //www. globus. org/ogsa

Requirements from OGSA Ÿ The secure connection and authentication mechanism underpins all GDS security and authentication Ÿ The lifetime management model carries over unchanged as the lifetime management model for GDS Ÿ The notification mechanism specified in OGSA appears to satisfy the GDS needs DAIS Grid 24

Requirements from OGSA (cont. ) Ÿ It is required information about the user authorization (potentially through many intermediate grid services) – User identification services, referenced from a certificate Ÿ Certification of the services themselves may be necessary. A discovery service could be tricked to mimic the intended GDS and get the data sent Ÿ Some databases charge for their use. It is necessary to support a digital payment process DAIS Grid 25

Current DAIS Standards and Systems DAIS Grid 26

DAIS Standards Ÿ Global Grid Forum – “The Global Grid Forum (GGF) is the community of users, developers, and vendors leading the global standardization effort for grid computing. ” http: //www. ggf. org/ Ÿ Part of the GGF: DAIS-WG – “The group seeks to promote standards for the development of grid database services, focusing principally on providing consistent access to existing, autonomously managed databases. ” https: //forge. gridforum. org/projects/dais-wg DAIS Grid 27

OGSA-DAI System Ÿ “The aim of the OGSA-DAI project is to develop middleware to assist with access and integration of data from separate sources via the grid…and is working closely with the Global Grid Forum DAISWG. . . ” http: //www. ogsadai. org/ Ÿ OGSA-DAI Overview http: //www. ggf. org/GGF 17/materials/303/Overview. ppt Ÿ Architecture + Extensibility http: //www. ggf. org/GGF 17/materials/303/GGF 17 Architecture. Extensibility. ppt Ÿ Supported Data Resources http: //www. ggf. org/GGF 17/materials/303/GGF 17 Architecture. Extensibility. ppt DAIS Grid 28

Conclusion DAIS Grid 29

Conclusion Ÿ This document has made a preliminary, service-oriented proposal for integrating database functionality into a Grid setting Ÿ It is hoped that the document will provoke discussion on how best databases can be integrated with Grid middleware Ÿ There is an establish community dedicated to defining DBMS service standards, and emerging system are adopting them DAIS Grid 30