10. Continuous Integration

Question 1

problems in integration

Answer 1

1. spend more time integrating than creating new features
2. problems occur as software evolves due to concurrent development
3. problems worsen when develop tries to:
   - integrate large change to code base
   - infrequent new feature integration

Question 2

continuous-integration practices

Answer 2

1. change management
   - maintain single source repository
   - everyone commit to main line everyday
   - every commit builds mainline
   - everyone can see what is happening
2. quality assurance
   - automate the build
   - make build self testing
   - test in a clone of the repository
   - keep the build fast
3. deployment
   - make it easy for anyone to get latest executable
   - automate deployment

Question 3

late integration

Answer 3

1. working on separate copy of source code for implementation
2. considerable amount of conflict for merging

Question 4

what is continuous integration

Answer 4

1. split work into small changes
2. integrate frequently
3. limit effect of exponential rate of divergence of the trunk

Question 5

feature branching option

Answer 5

1. implement new feature on trunk with frequent small commit
2. implement new feature on branch and merge frequently
3. implement feature as a prototype branch, then re-implement feature on the trunk in small changes
4. implement features as permanent branch

Question 6

maintain multiple continuous integration processes

Answer 6

1. main line trunk development
2. forked development for specified customer/purpose
3. latest stable release only receive defect fixes
4. significant feature branch

Question 7

monitoring and maintaining software quality

Answer 7

1. detecting broken builds
   - system should be compiled from source in clone repository
   - automated regression test executed on complete system
   - static analysis checks performed to compare with benchmarks

Question 8

preventing broken public builds (trunk)

Answer 8

flow…

Question 9

preventing broken public builds (branches)

Answer 9

flow…

Question 10

staging environment

Answer 10

1. environment configured to replicate conditions that software will be used in
2. configured with current hardware software dependencies
3. changes need to be checked before release
4. more than 1 staging environment may be needed.

Question 11

limitation of staging environment

Answer 11

1. system distributed on too many computing nodes to test realistic scenarios
2. system has too many simultaneous users
3. too many diverse user types
4. only one platform for software is available
5. software dependencies cannot be accessed outside of production

Question 12

monitoring and visibility

Answer 12

push notifications and broadcast mechanism

Question 13

monitoring metrics

Answer 13

1. unsuccessful builds
2. average unsuccessful test
3. time to build

Question 14

why are fast build essential

Answer 14

1. delays in completing also delays discovery of problems

2. developers deterred from making frequent commits as waiting for build to complete reduce productivity

Question 15

continuous deployment

Answer 15

1. automate deploying of software
2. advantages:
   - ensures that deployment process is used regularly
   - different features can be deployed to differentiate users