Database Server Concepts and Possibilities

Lee Lueking

D0 Data Browser Workshop

April 8, 2002

What Role Does The DB Server Play?• The DB server represents the middle tier of a three tier architecture.• Reference material available at http://d0db-dev.fnal.gov/db_server_gen

Client Client Client

DB Server

Database

CORBA

SQLnet

Oracle

What Are Pros and Cons of 3 Tier Architecture?

• Advantages• Significantly reduces the required number of concurrent client

licenses required (significant savings when using commercial db).• Enables any internet connected node to run client processes.• Insulates client from changes in DB schema, and visa versa.• Enables client applications to be coded in any language.• Much more scalable approach: 1) Allows customized caching and

other services to be built into middle tier, 2) Dbservers can be operated on “cheap” hardware.

• Disadvantages• Complex environment• Debugging at all tiers more complicated.• Adds additional level of abstraction for developers and users.• Reduces effectiveness of Oracle server caching and optimization

Where Do We Use DB Serves?

• SAM specific servers• SAM user (serves SAM users)• SAM prd (serves most SAM stations)• SAM web (dedicated to web-based dataset editor)• DLSAM (dedicated to online station)• Central-Analysis (dedicated to CA station)• D0 Farm (dedicated to D0 FNAL processing farm)

• Offline Trigger DB• Offline Luminosity • Generalized servers

• Offline Calibration (many)• Offline Run Config

Using a DB Server With a Browser

• Can easily develop a DB browser for any CORBA enabled framework.

• Could create interface ROOT interface to allow creation of ROOT trees for analysis (similar to Andrei’s approach).

• The web-based SAM dataset editor uses a Java Servlet and Java Server Pages (JSP) to provide a performant tool for viewing (and modifying in the SAM case) database tables.

• Other tools could be used, like php.

The SAM Dataset Definition Editor

• Uses the Apache and Tomcat (specific implementation of JS and JSP)

• Dataset definition editor

Future DB Server Features

• The Second Generation “general” DB server is now in design.

• Has much better caching, monitoring, connection, and robustness features.

• Jim can discuss this…