Code Generation

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Code Generation

• Tips
• Tricks
• Pitfalls

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Why?

• Speed up development
• DeltaX 8X
• Remove bugs
• Consistency
• Less flexibility

3
Why Not?

• May be difficult
• May not be appropriate
• Readability of generated code
• Debugability of generated code
• Less flexibility

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Example - DeltaX What

• High level design
• Detailed design
• API Document
• SNMP MIBs Database Access
• SNMP Agent functionality
• C SNMP Corba Classes ...
• GUI

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Example - DeltaX EMS

• EMS SNMP Agent
• API Document
• High Level Design
• MIB Master C Code
• Subagent Set CB
• Cache access
• API calls

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Example - DeltaX NMS

• NMS - C Corba Ilog GUI
• IDL
• Corba Impl
• DB schema access
• SNMP access
• Ilog GUI
• GUI C

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Example GUI
8
Lines
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Percent
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Tips

• Metadata
• Utility printing executables
• Parsing executables
• Integrated executables
• Shell here documents

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Metadata

• Describes the data
• Want it compiled in I.e., accessible in scripts
• Source code
• Database
• Metadata parser input file

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Parsing

• MibMaster etc.
• Bulk Code
• Metadata
• No Changes
• Generic
• Difficult to debug/change

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Integrated

• Based on intermediate metadata
• Can do complex tasks - e.g., if then else
• Difficult to modify

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Utilities

• PrintMibs
• Prints metadata
• Print 17 items per attribute
• Flexible - uses printf
• Absolute key

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Shell here document

• Use existing example
• Replace specifics with variables
• Enclose with cat ltlt EOF EOF
• Easy to read, write and debug
• New age of code generation

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Metadata Applications

• E.g., GOA
• Array of attributes
• Switch statements/virtual functions
• Very good for raw applications
• Low code base size
• Easy to add new ones dynamically
• Low code ability
• Difficult to add special cases

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Tricks

• How to identify
• Doing the same thing over and over
• Use generation when possible.
• Only use generation when possible.
• Only use generation when possible.
• Cut and Paste for small amounts.
• Dont try to be optimal initially

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Pitfalls

• Modifying Code
• Stub Files
• RCS
• ifdef wrappers
• Derived classes
• Registered Callbacks
• Dont generate as part of the normal build
• Code understandability

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Conclusions

• Generation can reduce time
• Use 90 generated 10 hand coded
• Use metadata based for raw apps
• Shell scripting is fast and readable.
• Take care when modifying generated code.

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References

• MM hptools/yacc
• PrintMibs mibmaster/008.Tools/print_mibs
• GOA mibmaster/007/src/monitor/goa
• gen nms nc867.15/007/src/gen_nms
• ems nc867.15/007/bin