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Client server
This document provides an overview and comparison of different client-server data access techniques in Visual FoxPro, including remote views, dynamic SQL pass-through, stored procedures, and cursor adapters. It evaluates these techniques based on categories like ease of use, performance/scalability, maintainability, flexibility, and security concerns. The document recommends choosing the best approach for each application and mixing techniques when necessary to achieve flexibility. It also encourages developers to be informed when selecting a data access strategy.
Client server
- 1. E-CS Client Server DataAccess Techniques with Visual FoxPro Mike Feltman F1 Technologies
- 2. Who Am I? • mfeltman@f1tech.com • F1 Technologies Partner • Visual FoxExpress Developer • Former Fox Software Employee • Application Programmer
- 3. Our Goals • Provideyou with an overview of each of the data access techniques • Make you aware of the pros and cons of the various techniques • Equip you with the information necessary to make an informed choice of data access technique.
- 4. Agenda • Overview ofVarious Data Access Techniques • Evaluation Categories – Ease of Use – Performance and Scalability – Maintainability – Flexibility – Security Concerns/Issues • Mixing and Matching Techniques
- 5. The Data AccessMethods • Remote Views • Dynamic SQL Pass-Through • Stored Procedures • CursorAdapter • ADO • XML
- 6. Ease of Use • UI and Tool Support • Data Binding • Normalcy • Completeness • Plays Well With Others • Distribution Difficulties
- 7. Remote Views • UI& Tools Support – View Builder, GenDBC – eView & View Editor – xCase – DBCX • Data Binding – Full Support in Data Environment • Normalcy – Most similar to tables
- 8. Remote Views • Completeness – Full Language Support in VFP – Limited Access to Back-end Features • Plays Well With Others – Very well, Can share connections • Distribution – DBC Distribution
- 9. Dynamic SPT –Ease of Use • UI and Tool Support – None Native, Some 3rd Party • Data Binding – Manual or Tricks • Normalcy – Requires More Code to work like a View (CursorSetProp())
- 10. Dynamic SPT –Ease of Use • Completeness – Access to full back-end • Plays well with others – Very well except for ADO • Distribution Issues – None
- 11. Stored Procedures –Ease of Use • UI and Tool Support – None in VFP – DataClas – Enterprise Manager and QueryAnalyzer – Mike Levy’s Classes from various conferences
- 12. Stored Procedures –Ease of Use • Completeness – Access to everything the back-end has to offer – Great for Multiple and/or Complex Statements • Distribution Difficulties – Must update stored procedures – Code Conflict Resolution
- 13. CursorAdapter with ODBC– Ease of Use • Similar to Remote Views • UI and Tool Support – CursorAdapter & DE Builder – 3rd Party Tools • Normalcy – Just like a Table or View
- 14. CursorAdapter with ODBC– Ease of Use • Completeness – More code than remote views, less than other techniques • Plays Well With Others – Easiest
- 15. CursorAdapter with ADO/OLEDB– Ease of Use • Similar to CursorAdapter with ODBC • Plays Well With Others – Cannot share connection with other data access strategies • Distribution Concerns – MDAC
- 16. Performance and Scalability •The differences between various techniques are generally minor. • Server, Workstation & LAN/WAN performance and scalability must ALL be taken into account • Size (& Contents) Matters • Query optimization in SQL Server is much different than in VFP. Syntax vs. Content-based optimization.
- 17. Performance and Scalability •Results can vary widely for the same tests. • Those with much more experience than me with large databases (million rows+) all swear Stored Procedures produce the best performance. • Microsoft tends to get very angry at those who publish SQL Server benchmarks.
- 18. Maintainability • Code Requirements – How much code? • Maintenance Points – How many? – Easy to find and work with? • Tools – Are there any? • Schema Changes – What happens when schema changes?
- 19. Maintainability - RemoteViews – Code Requirements • Little – Maintenance Points • Primarily the views themselves • Custom classes
- 20. Maintainability - RemoteViews – Tools • View Designer, eView, ViewEditor, xCase, GenDBC – Schema Changes • Use xCase • Unit test remote views
- 21. Maintainability - DynamicSPT – Code Requirements • One good base class • App specific subclasses – Maintenance Points • Custom Class Code
- 22. Maintainability - DynamicSPT – Tools • None – Schema Changes • Maybe do nothing • Unit test data access code
- 23. Maintainability - Stored Procedures – Code Requirements • VFP – One good set of classes • 4 or more Procedures for basically every table – Maintenance Points • Custom classes • Actual Stored Procedures
- 24. Maintainability - Stored Procedures – Tools • None for VFP • DataClas, 3rd Party – Schema Changes • All Procedures • Unit Test all Stored Procedures
- 25. Maintainability - CursorAdapters –Code Requirements • One good base class – Maintenance Points • Individual subclasses – Tools • 3rd party, DE and CA Builder – Schema Changes • Modify CA properties • Unit test all cursor adapters
- 26. Flexibility • Remote Views – Inflexible without other techniques • Dynamic SPT – Highly flexible with custom classes, but overly difficult to write
- 27. Flexibility • Stored Procedures – Very Flexible – Much like Dynamic SQL Pass-Through • Cursor Adapter – Most Flexible – mix & match with all techniques – Native class provides appropriate locations for customization
- 28. Security • Stored Procedures– Execute Rights on Stored Procedures Only • All Others – Provide direct rights to update tables or views • DSN Based Connection vs. Connection String is more important • Use Application Roles
- 29. Mixing and Matching •CURSORSETPROP() – Make SPT Cursor Updatable – Load data into remote view • USE … CONNSTRING (handle) • CursorAdapter.CursorAttach • SQLSTRINGCONNECT()
- 30. Summary • Be Informed! • It is Not an “All or Nothing” Situation • Choose the Best Approach for the Application • Mix and Match When Necessary.
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