Modernizing Legacy Applications in PHP

Cover......Page 1
Copyright......Page 3
Credits......Page 4
Foreword......Page 6
About the Author......Page 8
Acknowledgement......Page 9
www.PacktPub.com......Page 10
Table of Contents......Page 12
Preface......Page 20
Chapter 1: Legacy Applications......Page 22
  File Structure......Page 23
  Page Scripts......Page 24
  Rewrite or Refactor?......Page 25
  The Pros and Cons of Rewriting......Page 26
   The Context-switching problem......Page 27
   The Schedule Problem......Page 28
   Iterative Refactoring......Page 29
  Refactoring to a Framework......Page 30
 Review and next steps......Page 31
 Revision control......Page 32
  Editor/IDE......Page 33
 Test suite......Page 34
 Review and next steps......Page 35
 PSR-0......Page 36
  As a Global Function......Page 37
   As a Static or Instance method......Page 39
  Autoloader Priority......Page 41
  What are the Performance Implications Of Autoloading?......Page 42
  How Do Class Names Map To File Names?......Page 43
 Review and next steps......Page 44
 Consolidate Class Files......Page 46
  Find a candidate include......Page 47
  Remove the related include calls......Page 48
  Commit, Push, Notify QA......Page 50
 Consolidate functions into class files......Page 51
  Convert the function file to a class file......Page 52
   Change function calls to static method calls......Page 53
   Move the class file......Page 54
  Should we remove the autoloader include call?......Page 55
  What if the one-class-per-file rule is disagreeable?......Page 56
  What if a definition file also executes logic?......Page 57
  What about third-party libraries?......Page 59
   What about system-wide libraries?......Page 60
  For functions, can we use instance methods instead of static methods?......Page 61
 Review and next steps......Page 62
 Global Dependencies......Page 64
  The replacement process......Page 66
  Convert global variables to properties......Page 67
  Convert global properties to constructor parameters......Page 68
   Convert instantiations to use parameters......Page 69
  What if we find a global in a static method?......Page 71
  What about class names in variables?......Page 73
  What about superglobals?......Page 74
 Review and next steps......Page 76
 Embedded instantiation......Page 78
  Find a new keyword......Page 80
  Extract One-Time creation to dependency injection......Page 81
  Extract repeated creation to factory......Page 82
 Change instantiation calls......Page 84
   What About Exceptions and SPL Classes?......Page 85
   What about Intermediary Dependencies?......Page 86
   Isn't this a lot of code?......Page 89
   Should a factory create collections?......Page 90
  Can we automate all these Injections?......Page 91
 Review and next steps......Page 92
 Fighting test resistance......Page 94
 The way of Testivus......Page 95
   Install PHPUnit......Page 96
   Create a tests/ directory......Page 97
   Write a test case......Page 98
   Come On, Really, Can We Do This Later?......Page 100
   What about hard-to-test classes?......Page 101
   Do we need to test Third-party libraries?......Page 102
 Review and next steps......Page 103
 Embedded SQL Statements......Page 104
  The extraction process......Page 105
   Move SQL to a Gateway class......Page 106
   Method names......Page 107
  An initial Gateway class method......Page 108
   Defeating SQL Injection......Page 109
   Write a test......Page 111
   Test, Commit, Push, Notify QA......Page 113
   What about INSERT, UPDATE, and DELETE Statements?......Page 114
   What about Repetitive SQL strings?......Page 115
   What about complex query strings?......Page 117
   What about queries inside non-Gateway classes?......Page 121
   Can we extend from a base Gateway class?......Page 122
   What about multiple queries and complex result structures?......Page 123
   What if there is no Database Class?......Page 126
 Review and next steps......Page 128
Chapter 9: Extract Domain Logic to Transactions......Page 130
  Domain logic patterns......Page 131
 The Extraction Process......Page 133
   Discover and Extract Relevant Domain Logic......Page 134
   Example Extraction......Page 135
   Write tests for the extracted transactions......Page 137
   What about repeated Domain Logic?......Page 138
   Can a transaction be a class instead of a Method?......Page 139
   What about Domain logic embedded in Non-Domain classes?......Page 140
 Review and next steps......Page 141
 Embedded presentation logic......Page 142
  The Extraction process......Page 143
   Rearrange the Page script and Spot Check......Page 144
   Create a views/ Directory......Page 145
   Add Proper Escaping......Page 147
   The tests/views/ directory......Page 149
   What about Headers and Cookies?......Page 153
  What if we already have a Template system?......Page 155
   What about Streaming Content?......Page 156
  What if we have lots of Presentation variables?......Page 158
   What about class methods that generate output?......Page 160
  What about Business Logic Mixed into the presentation?......Page 161
 Review and next steps......Page 162
 Embedded action logic......Page 164
  Rearrange the Page Script and Spot Check......Page 165
   Spot Check the Rearranged Code......Page 166
   Create a Skeleton Class File......Page 167
  Move the Action Logic and Spot Check......Page 168
  Convert Controller to Dependency Injection and Spot Check......Page 169
   Can we pass parameters to the Controller method?......Page 170
  What If the Controller contains include Calls?......Page 172
 Review and next steps......Page 173
 Embedded include Calls......Page 174
 The Replacement process......Page 176
  Replacing a Single include Call......Page 177
  Replace the original include Call......Page 178
  Discover coupled variables through testing......Page 179
   Convert to Dependency Injection and test......Page 181
   Commit, Push, Notify QA......Page 183
 Review and next steps......Page 184
 Intermingled resources......Page 186
  Coordinate with operations personnel......Page 187
  Create a document root directory......Page 188
  Reconfigure the server......Page 189
  Move public resources......Page 190
 Review and next steps......Page 191
 Coupled Paths......Page 192
   Add a Front Controller......Page 193
   Create a pages/ Directory......Page 194
  Reconfigure the Server......Page 196
   Move Page scripts......Page 197
   Commit, Push, Coordinate......Page 198
 Review and next steps......Page 199
 Repeated logic......Page 200
  Modify the Front controller......Page 201
  Remove Logic from Page Scripts......Page 202
   What if the Setup Work Is Inconsistent?......Page 203
 Review and next steps......Page 204
 What is a Dependency Injection Container?......Page 206
  Adding a DI Container......Page 207
  Add a DI Container Include File......Page 208
   Add a Router Service......Page 209
   Modify the Front Controller......Page 210
   Extract Page Scripts to Services......Page 211
   How can we refine our service definitions?......Page 214
   Can we reduce the size of the router service?......Page 216
   What if we cannot update to PHP 5.3?......Page 217
 Review and next steps......Page 219
 Opportunities for improvement......Page 220
 Review and next steps......Page 222
Appendix A: Typical Legacy Page Script......Page 224
Appendix B: Code before Gateways......Page 234
Appendix C: Code after Gateways......Page 242
Appendix D: Code after Transaction Scripts......Page 250
Appendix E: Code before Collecting Presentation Logic......Page 258
Appendix F: Code after Collecting Presentation Logic......Page 262
Appendix G: Code after Response View File......Page 266
Appendix H: Code after Controller Rearrangement......Page 270
Appendix I: Code after Controller Extraction......Page 272
Appendix J: Code after Controller Dependency Injection......Page 276
Index......Page 280