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[Notes] CSCI 585 discussion 4

02 Mar 2020 | CSCI585, English/英文, Note

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DB connectivity

On Windows, what’s at a lower level than JDBC?

  • JAVA connect database, ODBC

ODBC, DAO, RDO etc are implemented as DLLs, in Windows - what is a DLL, what is the eqvt in Unix/Linux?

  • DLL is dynamic-link library. without ddl whole library will be static complication and hard to update, easy fail , in linus is .DSO

In OLE-DB [and elsewhere], what is COM/DCOM/COM+? [info]

  • OLE(object linking and embedding), COM (component object model) common object, D for distribute

CORBA: “The (ORB, object request broker) is the middleware that establishes the client-server relationships between objects. Using an ORB, a client can transparently invoke a method on a server object, which can be on the same machine or across a network. The ORB intercepts the call and is responsible for finding an object that can implement the request, pass it the parameters, invoke its method, and return the results. The client does not have to be aware of where the object is located, its programming language, its operating system, or any other system aspects that are not part of an object’s interface. In so doing, the ORB provides interoperability between applications on different machines in heterogeneous distributed environments and seamlessly interconnects multiple object systems.” – http://www.omg.org/

Perl CGI (common gateway interface), OPC, CPAN

  • page -> CGI -> database
  • obfuscation perl contest
  • The Comprehensive Perl Archive Network

XML - history, applications…?

  • extensible markup language

CORBA vs SOAP/WSDL/UDDI?

  • SOAP (Simple Object Access Protocol) is a message protocol that allows distributed elements of an application to communicate
  • web serves description language
  • UDDI stands for Universal Description, Discovery, and Integration
  • REST Representational state transfer

Web services use a ‘publish - find - bind’ model…

Web services characteristics?

  • independence

Performance tuning

Statistical vs rule-based query optimization - ring a bell?

  • ai before is symbolic -> data

Online, an example of hashing being used?

  • password, url shotting

Multiple index keys in the same hash bucket?

  • hash collision, add extra bit to distinguish or save all values

Unbalanced b-trees

  • rebuild the tree (e.g. rotate the node)

Columns worth creating indices for?

  • sparsity, columns that appear in query (in where condition)

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