Chris Menegay Sr. Consultant TECHSYS Business Solutions Data Access Patterns Chris Menegay Sr. Consultant TECHSYS Business Solutions

Agenda Data Access Methodology Techniques for Data Access Summary Data Access Layer Techniques for Data Access ADO.NET Datasets Datareaders Microsoft Data Access Application Blocks SQLXML Summary

Data Most applications deal with data that is persisted in some manner RDBMS Flat file Mainframe XML Need a consistent way to write code to take application data and persist it.

Selecting a Solution There is more than one ‘right way’ You are part of the answer… …your skills …your background …your familiarity What are you doing with the data? Does it contain business logic? What tools are you using with it? What is the destination of the data? Are you exchanging it with other partners? What type of project are you working on? Self-contained app versus enterprise framework

Layered Architecture Pattern Users Operational Management Security Communication UI Components UI Process Components Service Interfaces Business Workflows Business Components Business Entities Data Access Components Service Agents Data Sources Services

Data Access Layer Contains all data access code. Contains only data access code. Does not contain business code. Does not contain UI code. Tip: Use IDBConnection, IDBCommand, etc.

Q: Why am I doing this? Consistency and Maintenance It scales – works for small applications as well as large ones Never have to wonder ‘where is all the code that accesses the customer table?’ Tip: you can code generate a lot of this

Data Access Layer

ADO.NET Data Access Support Data is relational is objects is XML is Data Technology Strengths Use if… DataSet and DataReader in ADO.NET Relational (tabular) model Highest performance Explicit control Fully exposes database functionality You are comfortable with the relational model You require maximum control/performance/functionality You are using UI bound controls Interoperability. Format for the Web – B2B, A2A Sparse (semi-structured) data XML Services e.g. XQuery, XSD Relational mapping via metadata Decoupled from database schema You need to query data from XML data sources e.g. XML Web Services You use vertical industry XML schemas for content publishing e.g. XBRL, RIXML, FinXML You need to load XML documents into database tables You are using UI bound controls for XML SQLXML in ADO.NET

DataSets And Datareaders Use Datasets for: Holding data in memory – great for winforms applications with databinding. Allow sorting and filtering at the client Combine results from multiple stores Use Datareaders for: Read once data Speed

Data Access Helpers

Why a helper block? Consistent mechanism for accessing data Simplifies code

Microsoft Data Access Application Block

DataSets And Data Providers Overview Architecture Scenarios Demo

.NET Data Providers: Overview Goal: Integrate manipulation of relational data with the .NET Framework Accessing a Relational Store (.NET Data Providers) Connecting, Executing Commands, Retrieving Results Explicit Architecture Provided a defined interface: IDBConnection IDBCommand, etc Predictable behavior, semantics Optimized performance

DataSet And Data Providers: Architecture DataAdapter .NET Data Provider DataReader Command Connection

Data Providers & Helper Blocks

SQLXML Overview Architecture Scenarios Demo

SQLXML: Overview Growing number of applications unifying under XML based interfaces Loose coupling Coping with decentralized data Managing sparse (semi-structured) data SQLXML supports XML over SQLServer XML programming model for queries and updates XQuery(Whidbey) - Full fledged XML query language XML Views Mapping technology to expose logical XML views of SQL Server relational tables XML Views provide XQuery support over SQL Server.

ADO.NET With SQLXML

SQLXML: Scenarios Represent data as XML Source and sink for XML Content management systems, B2B scenarios Queries and updates against XML Views Loading large XML data sets Bulk load data into existing relational table structure E.g. Catalog information Transfer data as XML between databases Agree on transfer format Apply mappings at either end

SQLXML

Summary It’s all about DATA… Plan how you want to access/maintaing your data Structure your code! Understand the strengths of each technology DataSet and Datareader Relational Model Ultimate Performance, Control SQLXML XML Model Interoperable, self-describing format Pick the technology appropriate to your scenario How results will be used Tools to be applied Your knowledge/comfort level

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