DialogOnSoftwareProjectManagement.rst: lecture notes on 9 March 2020..

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@@ -16,6 +16,856 @@ Preface
 This book contains a series of special lecture notes in a dialog form on software project management during the Great Lockdown period due to the outbreak of 2019 novel coronavirus.
 
 
+Monday, 9 March 2020
+====================
+
+
+Morning section
+----------------
+
+*Sustained efforts - How to earn 1b 10 years later - Software licenses - Copyleft - Non-copyleft - Commercial - Non-commercial - Proprietary - Non-proprietary - Quiz*
+
+
+蓝老师(1348141770)  ===================================================
+
+蓝老师(1348141770)  Morning guys.  Could you type your student number?
+
+2020-03-09 10:36:06 ibrahim(1525200991)  201732120159
+
+2020-03-09 10:36:06 201732120167 Clive妈妈(3321692247)  201732120167
+
+2020-03-09 10:36:07 软英171周仙龙(1748153603)  201732120130
+
+2020-03-09 10:36:08 201732120141--AHAMED SABUJ妈妈(2686217157)  201732120141
+
+2020-03-09 10:36:08 201732120168_Golden(2984538488)  201732120168
+
+2020-03-09 10:36:08 201732120127 张滨(2350711965)  201732120127
+
+蓝老师(1348141770)  It is useful for me.
+
+2020-03-09 10:36:11 201732120134_Michelle(3304952232)  201732120134
+
+2020-03-09 10:36:11 201732120165 MJH MOHAMED(2751595398)  201732120165
+
+2020-03-09 10:36:15 软英171高增(1520653544)  201732120117
+
+2020-03-09 10:36:16 李佳兴(421281726)  201732120118
+
+2020-03-09 10:36:16 201632120150-Ashly(1661411131)  201632120150
+
+2020-03-09 10:36:16 软英171 吕伊豪(745291576)  201732120120
+
+2020-03-09 10:36:17 nainezz(2407048879)  201732120173
+
+2020-03-09 10:36:17 叶涵涛(2289316051)  201732120125
+
+2020-03-09 10:36:24 201732120170-Tamene Robel妈妈(3287975278)  201732120170
+
+2020-03-09 10:36:29 Saeed : 201732120146(446571011)  201732120146
+
+2020-03-09 10:36:49 201732120157 hossain arif<charif19282@qq.com>  201732120157
+
+蓝老师(1348141770)  Let's wait 4 minutes for more people to join in.
+
+2020-03-09 10:37:06 Saeed : 201732120146(446571011)  ok
+
+2020-03-09 10:37:12 软英171包振丰(984456043)  201732120111
+
+2020-03-09 10:37:19 应宇腾(1356633192)  20732120126
+
+2020-03-09 10:37:24 软英171陈伟超(937202326)  201732120113
+
+2020-03-09 10:37:33 陈真赐(1312502742)  201732120114
+
+2020-03-09 10:37:58 软英171郑洪宇(1633787262)  201732120128
+
+2020-03-09 10:37:59 系统消息(10000)  201732120165 MJH MOHAMED邀请201732120165_Mohamed_Jifry_Hazzaly加入了本群。
+
+2020-03-09 10:38:14 谢佳聪(1249923715)  201732120123
+
+2020-03-09 10:38:17 郑晓钰(280768265)  201732120110
+
+2020-03-09 10:38:22 软英171 郑可富(1924773187)  201732120129
+
+2020-03-09 10:39:01 ALBOROM WARD-201732120143家长(3279308836)  201732120143
+
+2020-03-09 10:39:11 201732120135 玛莎(3534763826)  201732120135
+
+2020-03-09 10:39:25 软英171 陆博业(2794513466)  201732120119
+
+2020-03-09 10:40:06 SPM软件项目管理-蓝老师(1348141770)  [Announcement] We will have a pop-up quiz, near the end of today's lecture.
+
+2020-03-09 10:40:15 Tarmom 201732120166(2104297320)  201732120166
+
+2020-03-09 10:40:35 1n(2835813510)  201732120102
+
+2020-03-09 10:40:36 SPM软件项目管理-蓝老师(1348141770)  Make sure you can login LRR.
+
+2020-03-09 10:40:54 Saeed : 201732120146(446571011)  yes
+
+2020-03-09 10:40:58 SPM软件项目管理-蓝老师(1348141770)  There is a recent story about LRR.
+
+2020-03-09 10:40:58 软英171戴泽荣(975336710)  201732120115
+
+2020-03-09 10:41:00 Tarmom 201732120166(2104297320)  laoshi I can't
+
+2020-03-09 10:41:10 Saeed : 201732120146(446571011)  try now
+
+2020-03-09 10:41:23 Tarmom 201732120166(2104297320)  ok
+
+2020-03-09 10:41:33 Npl.(593635848)  201732120121
+
+蓝老师(1348141770)  (Tarmom, you should first sign up.)
+
+蓝老师(1348141770)  Ashly updated LRR so that a CRITICAL bug is gone.
+
+蓝老师(1348141770)  I think most of you guys encountered that bug before.
+
+蓝老师(1348141770)  That is, you were unable to sign in immediately after sign up.
+
+2020-03-09 10:42:46 LUL GUOBA RUOT (2217724540)  201632120161
+
+蓝老师(1348141770)  This bug makes the software essentially not usable.
+
+蓝老师(1348141770)  A really bad bug.
+
+蓝老师(1348141770)  You had to recover your password by email (which did not always work).
+
+2020-03-09 10:43:37 Samantha 201632120140(2459455104)  201632120140
+
+蓝老师(1348141770)  It is absurd that we require people to recover their password immediately after they sign up.
+
+蓝老师(1348141770)  Ashly fixed that.
+
+蓝老师(1348141770)  Suddenly the software looks much better.
+
+蓝老师(1348141770)  Where did Ashy learn PHP?
+
+2020-03-09 10:45:27 201632120150-Ashly(1661411131)  Personal projects Laoshi
+
+蓝老师(1348141770)  There are a lot of existing talents.  A manager's job is to recognize them and cultivate them.
+
+蓝老师(1348141770)  That is a Great Fix.
+
+蓝老师(1348141770)  But that fix introduced a new problem.
+
+蓝老师(1348141770)  The old users were no longer able to login, which is almost equally bad.
+
+蓝老师(1348141770)  This is an example of failed regression test.
+
+蓝老师(1348141770)  The new fix breaks old, functional work.
+
+蓝老师(1348141770)  That is quite normal.
+
+蓝老师(1348141770)  The old, legitimate users saw a Blank Page after they logged in, leaving them totally perplexed.
+
+蓝老师(1348141770)  How to solve that?
+
+蓝老师(1348141770)  It turns out the fix is really simple.
+
+蓝老师(1348141770)  [图片]
+
+::
+
+    //  verify the hashed password and unhashed password
+    if(password_verify($password, $row["Password"]) or ($password = $row["Password"])){
+
+
+蓝老师(1348141770)  Just relax the conditional test by adding an OR condition: ($password = $row["Password"]).
+
+蓝老师(1348141770)  The reason is that the old password is not hashed (encrypted).
+
+蓝老师(1348141770)  We must hash people's password by law.
+
+蓝老师(1348141770)  Hash is like a one-way function.
+
+蓝老师(1348141770)  Hash('secrete') gives you a 64 obfuscating characters.
+
+蓝老师(1348141770)  But you cannot recover 'secrete' even if you know these 64 characters.
+
+蓝老师(1348141770)  That is my understanding of one-way.
+
+蓝老师(1348141770)  This small fix solved a Big problem.
+
+蓝老师(1348141770)  That is a great start.
+
+蓝老师(1348141770)  I can even say Ashly is done on the course project.
+
+蓝老师(1348141770)  However, I still hope he could do a bit more.
+
+2020-03-09 10:53:08 Tarmom 201732120166(2104297320)  laoshi still I can't sign up on LRR it's not working.
+
+蓝老师(1348141770)  (Fine.  I will create one for you during the break.)
+
+2020-03-09 10:53:46 Tarmom 201732120166(2104297320)  thank you
+
+蓝老师(1348141770)  Returning to storing password in LRR, can we hash all existing, old passwords so that we can remove the additional OR condition: ($password = $row["Password"])?
+
+蓝老师(1348141770)  Simpler code.
+
+蓝老师(1348141770)  Is it worth doing that?
+
+蓝老师(1348141770)  We have more than 200 accounts now in LRR.
+
+蓝老师(1348141770)  Let us take a 5-minute break.
+
+2020-03-09 10:55:31 Saeed : 201732120146(446571011)       ok
+
+2020-03-09 10:57:17 Tarmom 201732120166(2104297320)  ok
+
+2020-03-09 10:58:46 LUL GUOBA RUOT (2217724540)  Me too I can’t login
+
+蓝老师(1348141770)  ===================================================
+
+蓝老师(1348141770)  That is interesting.  You two guys could sign up again.  I believe it should work now.
+
+蓝老师(1348141770)  What have I learned from this improvement process?
+
+蓝老师(1348141770)  Good software takes time.
+
+蓝老师(1348141770)  Sustained efforts are required to build something that is really great so that people would pay to use it.
+
+蓝老师(1348141770)  You need at least 10 years.
+
+蓝老师(1348141770)  But after 10 years, you will be good, earning billions of dollars a year.
+
+蓝老师(1348141770)  Here is an article I want to share with you.
+
+蓝老师(1348141770)  https://www.joelonsoftware.com/2001/07/21/good-software-takes-ten-years-get-used-to-it/
+
+2020-03-09 11:05:51 Npl.(593635848)  很多人看不到这么远 一年就够呛的
+
+2020-03-09 11:06:18 Npl.(593635848)  [表情]
+
+蓝老师(1348141770)  Yes.  That is true.  That is why we have very few companies which have a yearly revenue of billions.
+
+蓝老师(1348141770)  I doubt LRR could sustain such a long period.
+
+蓝老师(1348141770)  Look at QQ, which started around 1998.
+
+蓝老师(1348141770)  How many years have passed?
+
+蓝老师(1348141770)  More than 20 years!
+
+蓝老师(1348141770)  The current QQ is much better than the original QQ (which is a clone of OICQ).
+
+蓝老师(1348141770)  I would say most people who have not taken this course don't realize that.
+
+蓝老师(1348141770)  Software is hard. And hard things need time. As simple as that.
+
+蓝老师(1348141770)  [图片]
+
+.. image:: lotus-note-user-pool.png
+   :height: 100
+   :alt:  number of installations of the Lotus Notes over the years
+
+蓝老师(1348141770)  User pool of Lotus Notes.
+
+蓝老师(1348141770)  It hit 55 million users in 1999.
+
+蓝老师(1348141770)  55 million users means lots of money and great influence.
+
+蓝老师(1348141770)  12 years have passed since the author(s) wrote the first line of code.
+
+2020-03-09 11:11:47 ibrahim(1525200991)  most people dream that thier software blow up like Facebook did
+
+蓝老师(1348141770)  The problem of China software industry is exactly Lack of Time.
+
+蓝老师(1348141770)  Desire of Success + Lack of Time = ?
+
+2020-03-09 11:13:06 Npl.(593635848)  failure
+
+蓝老师(1348141770)  [图片]
+
+蓝老师(1348141770)  How much money has Oracle made?
+
+蓝老师(1348141770)  Billions of dollars at least.
+
+2020-03-09 11:14:01 Npl.(593635848)  [图片]
+
+蓝老师(1348141770)  The Oracle database system was there in 1970's.
+
+2020-03-09 11:14:02 Npl.(593635848)  复利曲线
+
+蓝老师(1348141770)  (Oh, really.  That is a good observation.)
+
+蓝老师(1348141770)  This gentleman, Joel Spolsky, the founder of Stack Overflow, is good at writing.
+
+蓝老师(1348141770)  He is a very prolific author.
+
+蓝老师(1348141770)  Produced more than 1000 blog posts over a period of 10 years.
+
+蓝老师(1348141770)  I think you should read his "Top 10" posts.
+
+蓝老师(1348141770)  Let's take a 5-minute break.
+
+2020-03-09 11:17:41 系统消息(10000)  Npl.撤回了一条消息
+
+2020-03-09 11:22:01 Npl.(593635848)  I’ve looked through several his books (his blogs sets, more currently), he thinks most programmers are not true programmer. And it would be good if these “fake programmers” been fired(filter out).[表情]
+
+2020-03-09 11:23:39 ALBOROM WARD-201732120143家长(3279308836)  [表情]
+
+蓝老师(1348141770)  Npl seems like a motivated learner.  We need more self-driven learners.
+
+蓝老师(1348141770)  ===================================================
+
+蓝老师(1348141770)  Writing is Thinking.  Writing is Communicating.
+
+蓝老师(1348141770)  You must sharpen your writing skills before you graduate.
+
+蓝老师(1348141770)  Programming is more like a liberal and arts subject.
+
+蓝老师(1348141770)  Think about that.
+
+2020-03-09 11:26:26 Npl.(593635848)  “Talking” with the computer
+
+蓝老师(1348141770)  If you could earn 1 billion dollars 10 years later by focusing on developing one thing, and leading a very frugal life in these 10 years, would you do that?
+
+蓝老师(1348141770)  I think many people will do that.
+
+蓝老师(1348141770)  That is about 100,000,000 dollars per year.
+
+蓝老师(1348141770)  However, since there is no success guarantee, many people would choose to be a less disciplined person.
+
+蓝老师(1348141770)  We talked about software licenses last time.
+
+蓝老师(1348141770)  One question.
+
+蓝老师(1348141770)  What kind of free license would you use if your software is an online application, i.e., you do not send people installation packages?
+
+蓝老师(1348141770)  Apache, GPL, or MIT?
+
+2020-03-09 11:30:46 ibrahim(1525200991)  MIT
+
+蓝老师(1348141770)  License for online application, things like Simple Note, One Note.
+
+蓝老师(1348141770)  I think MIT is a good one.  It is simple and permissive.
+
+2020-03-09 11:31:25 ibrahim(1525200991)  or AGPL
+
+蓝老师(1348141770)  I want to mention Affero GPL.
+
+蓝老师(1348141770)  Exactly.
+
+蓝老师(1348141770)  Affero GPL has an extra clause designed specifically for online applications.
+
+蓝老师(1348141770)  Are GPL-like licenses MIT-compatible?
+
+蓝老师(1348141770)  Or Are MIT-like licenses GPL-compatible?
+
+蓝老师(1348141770)  GPL is a copyleft license, while MIT is a non-copyleft license.
+
+蓝老师(1348141770)  What does "copyleft" mean?
+
+蓝老师(1348141770)  Copyleft is an interesting word.
+
+2020-03-09 11:33:30 ibrahim(1525200991)  your code can't be used by proprietary software
+
+蓝老师(1348141770)  I don't know that before yesterday.
+
+2020-03-09 11:33:39 ibrahim(1525200991)  I guess
+
+2020-03-09 11:34:05 Dean Majaya201732120164爷爷(3623840484)   201732120164
+
+蓝老师(1348141770)  The exact meaning of copyleft is that all its derivative work under the copyleft license must be copyleft too.
+
+蓝老师(1348141770)  MIT license does not require that.
+
+蓝老师(1348141770)  If you use the code that is under the MIT license, you could apply a proprietary license to your software.
+
+蓝老师(1348141770)  That is why we say MIT license is a permissive license.
+
+蓝老师(1348141770)  The point of copyleft is ensuring that the subsequent (or derivative) work is also free.
+
+蓝老师(1348141770)  However, the danger is that people would rather not use your code in the first place if they think they don't agree with this condition.
+
+蓝老师(1348141770)  A rule of thumb is that if you do not care how your code is to be used, you could use either MIT or GPL or Apache.
+
+蓝老师(1348141770)  If you do not wish proprietary software to use your code, use GPL-like licenses.  They are more restrict on ensuring subsequent freedom.
+
+蓝老师(1348141770)  Note the difference between proprietary and commercial.
+
+蓝老师(1348141770)  They are not the same thing.
+
+蓝老师(1348141770)  A commercial software can be non-proprietary.
+
+蓝老师(1348141770)  A proprietary software can be non-commercial.
+
+蓝老师(1348141770)  Proprietary emphasizes "Owner",
+
+蓝老师(1348141770)  while commercial emphasizes "Money".
+
+蓝老师(1348141770)  [Announcement]
+
+蓝老师(1348141770)  "Decide areas for improvement" is due today.
+
+蓝老师(1348141770)  You need to finish reading Chapter 2 by the end of this week.
+
+蓝老师(1348141770)  Let's take a 5-minute break.
+
+2020-03-09 11:44:36 ALBOROM WARD-201732120143家长(3279308836)  Laoshi how about course scheduler would you let me manage it as my course project?
+
+蓝老师(1348141770)  ===================================================
+
+蓝老师(1348141770)  My main concern is that there are tons of Course Scheduling applications out there.
+
+蓝老师(1348141770)  Your efforts will be wasted on just producing yet-another Course Scheduling application.
+
+蓝老师(1348141770)  Anyway, we could discuss that more after class.
+
+2020-03-09 11:51:24 ALBOROM WARD-201732120143家长(3279308836)  ok laoshi
+
+蓝老师(1348141770)  You need to finish reading Chapter 2 by the end of this week.
+
+蓝老师(1348141770)  I could finish reading one chapter in one evening.
+
+蓝老师(1348141770)  I don't know your reading speed.
+
+2020-03-09 11:52:23 KELVIN Chimtengo(3110702155)  One week is enough.
+
+蓝老师(1348141770)  You can use lots of aids that are available online, such as the Bing translator.
+
+2020-03-09 11:53:01 ALBOROM WARD-201732120143家长(3279308836)  i can finish it in 3-5 hours
+
+2020-03-09 11:53:34 201732120151 Barkay sanoussi(3178573723)  reading  is not a big deal but understanding  is ..
+
+2020-03-09 11:53:57 Saeed : 201732120146(446571011)  yes
+
+蓝老师(1348141770)  To understand it, repeat the reading process.
+
+蓝老师(1348141770)  Repeat it at least three times.
+
+2020-03-09 11:54:26 ibrahim(1525200991)  do you want us to just read it, or understand and highlight some points, if the later then that takes some time
+
+蓝老师(1348141770)  I think the most important purpose of reading is understanding.
+
+2020-03-09 11:55:14 ALBOROM WARD-201732120143家长(3279308836)  yeah that's why i said 3-5 hours including highliting and understanding
+
+蓝老师(1348141770)  Otherwise, Microsoft Edge could read it for us.
+
+2020-03-09 11:55:27 Npl.(593635848)  There is no reading speed, only understanding speed
+
+蓝老师(1348141770)  I will post a new, longer reading: The Cathedral and the Bazaar.
+
+蓝老师(1348141770)  http://catb.org/~esr/writings/cathedral-bazaar/cathedral-bazaar/index.html
+
+蓝老师(1348141770)  It discusses 2 development modes.
+
+蓝老师(1348141770)  You don't have to read all, only a few selected sections.
+
+2020-03-09 11:56:45 ALBOROM WARD-201732120143家长(3279308836)  that would be better
+
+蓝老师(1348141770)  I want to maximize the usefulness of this course while minimizing your workload.
+
+蓝老师(1348141770)  I will post the required sections.
+
+蓝老师(1348141770)  Quiz time.
+
+2020-03-09 11:58:36 ibrahim(1525200991)  wish most teacher follow your theme
+
+蓝老师(1348141770)
+
+::
+   
+   [True/False] Free software means zero-cost software.
+   [True/False] Zero-cost software cannot be proprietary.
+   [True/False] If the source code is visible, then the software is open source.
+   [True/False] Open source software cannot be used for commercial purposes.
+
+蓝老师(1348141770)  You select two of them to answer.
+
+蓝老师(1348141770)  Submit it at LRR (under Quiz 3).
+
+蓝老师(1348141770)  Before 12:15pm.
+
+蓝老师(1348141770)  Bye.
+
+2020-03-09 11:59:39 ibrahim(1525200991) what if i answer all of them ?
+
+2020-03-09 11:59:46 nainezz(2407048879) Bye
+
+2020-03-09 11:59:53 ABDALMUHAYMEN 201730210234(1071107298) Bye
+
+2020-03-09 11:59:59 Saeed : 201732120146(446571011) ok
+
+蓝老师(1348141770)  Please just answer two questions.
+
+2020-03-09 12:00:18 1n(2835813510) only true or false or explanation also
+
+2020-03-09 12:00:21 KELVIN Chimtengo(3110702155) We should post answers here? Or ?
+
+蓝老师(1348141770)  The two which you feel most confident about.
+
+蓝老师(1348141770)  Just True or False.  No explanation.
+
+2020-03-09 12:00:43 1n(2835813510) ok
+
+2020-03-09 12:00:43 ALBOROM WARD-201732120143家长(3279308836) Submit it at LRR (under Quiz 3).
+
+2020-03-09 12:01:40 KELVIN Chimtengo(3110702155) Okay cool
+
+2020-03-09 12:01:56 KELVIN Chimtengo(3110702155) 201632120149
+
+2020-03-09 12:02:51 201732120170-Tamene Robel妈妈(3287975278) LRR not working
+
+
+
+Afternoon Section
+-----------------
+
+*Project management tools - Kanboard - Swim lanes - Rhythm of releases - Sustained efforts - Joel Spolsky - Software licenses*
+
+Lan Hui(1348141770)  ===================================================
+
+Lan Hui(1348141770)  Good afternoon.
+
+2020-03-09 15:41:41 Guedalia Youma (3014432207)  Good afternoon professor
+
+Lan Hui(1348141770)  Could you type your student number?  It is useful for me.
+
+2020-03-09 15:41:59 NGOUNOU家长(438499151)  good afternoon laoshi
+
+Lan Hui(1348141770)  I am going to get some hot water.
+
+2020-03-09 15:42:05 Guedalia Youma (3014432207)  201925800221
+
+Lan Hui(1348141770)  Let's wait a few minutes for more people to join in.
+
+2020-03-09 15:42:26 NGOUNOU家长(438499151)  201925800180
+
+2020-03-09 15:42:36 Marie(2928285277)  201925800173
+
+2020-03-09 15:42:36 NGOUNOU家长(438499151)  OK
+
+Lan Hui(1348141770)  Where were we last time?
+
+Lan Hui(1348141770)  I've talked about an important management tip: Don't THROW AWAY YOUR CODE.
+
+Lan Hui(1348141770)  This tip was given by Joel Spolsky, founder of Stack Overflow.
+
+Lan Hui(1348141770)  Also Trello, a $425m product for project management.
+
+2020-03-09 15:45:29 Kumson爸爸(3157209053)  201925800166
+
+Lan Hui(1348141770)  I was thinking about using Trello.
+
+Lan Hui(1348141770)  There are many project management tools out there.
+
+Lan Hui(1348141770)  Trello, JIRA, Microsoft Project, etc.
+
+Lan Hui(1348141770)  I should choose a simpler one.
+
+Lan Hui(1348141770)  So I choose Kanboard.
+
+Lan Hui(1348141770)  https://kanboard.org/
+
+Lan Hui(1348141770)  Have you checked that?
+
+Lan Hui(1348141770)  I can show you in a moment.
+
+Lan Hui(1348141770)  [图片]
+
+.. image:: TIM20200316180248.png
+   :height: 100
+   :alt: Kanboard for undergraduate thesis supervision
+
+Lan Hui(1348141770)  You can see many cards, in different colors and in different swim lanes.
+
+Lan Hui(1348141770)  We've got 4 swim lanes, representing different project stages.
+
+Lan Hui(1348141770)  The leftmost is **TODO**.
+
+Lan Hui(1348141770)  Followed by **Ready**.
+
+Lan Hui(1348141770)  Followed by **In Progress**.
+
+Lan Hui(1348141770)  Followed by **Done**.
+
+Lan Hui(1348141770)  To avoid multi-tasking, we should minimize the number of cards (tasks) in the **In Progress** swim lane,
+
+Lan Hui(1348141770)  which seems to be not the case in my Kanboard.
+
+Lan Hui(1348141770)  That is why I feel exhausted.
+
+2020-03-09 15:51:19 Nicole Rutagengwa (1403962700)  201935800169
+
+Lan Hui(1348141770)  We can move the cards (tasks) around.
+
+Lan Hui(1348141770)  I plan to ask you to use Kanboard (in our course).
+
+Lan Hui(1348141770)  I will create accounts for you within one week.
+
+Lan Hui(1348141770)  I've also talked about rhythm of releases and the importance of having and keeping that rhythm.
+
+Lan Hui(1348141770)  In the beginning, we should release early and often.
+
+Lan Hui(1348141770)  But when our product becomes more mature, releasing too often is a bit annoying to users (once in a half year is good enough).
+
+Lan Hui(1348141770)  Sometimes people just do not need that many new features if the product has already satisfied their daily use.
+
+Lan Hui(1348141770)  [Announcement] We will have a pop-up quiz, near the end of today's lecture.
+
+Lan Hui(1348141770)  Make sure you can login LRR (Lab Report Repository).
+
+Lan Hui(1348141770)  There is a recent update for LRR.
+
+Lan Hui(1348141770)  Last lecture I mentioned a CRITICAL (even BLOCKER) bug in LRR.
+
+Lan Hui(1348141770)  A new user could not login immediately after sign up.
+
+Lan Hui(1348141770)  That bug was fixed by Ashly, an undergraduate student in the morning section.
+
+Lan Hui(1348141770)  Suddenly, the software looks much better.
+
+2020-03-09 16:00:21 Marie(2928285277)  So do we need to sign up again
+
+Lan Hui(1348141770)  You don't have to recover your password by email, which does not always work, and is quite absurd.
+
+Lan Hui(1348141770) (No.)
+
+Lan Hui(1348141770)  But that fix introduced a new problem.
+
+Lan Hui(1348141770)  The old, legitimate users are no longer able to login, which is equally bad as being unable to login immediately after sign up.
+
+Lan Hui(1348141770)  The fix failed that Regression Test.
+
+Lan Hui(1348141770)  Failing a regression test is quite normal.
+
+Lan Hui(1348141770)  Two old users reported that they saw a Blank Page after they logged in, making them totally surprised.
+
+Lan Hui(1348141770)  Let's take a 5-minute break.
+
+2020-03-09 16:07:43 Guedalia Youma (3014432207)  Alright
+
+Lan Hui(1348141770)  Where is Pacifique?
+
+2020-03-09 16:12:59 系统消息(10000)  Twizere Pacifique 唐平撤回了一条消息
+
+2020-03-09 16:13:12 Twizere Pacifique 唐平<pacitwizere@hotmail.com>  201925800174
+
+Lan Hui(1348141770)  Thanks, Pacifique.
+
+Lan Hui(1348141770)  ===================================================
+
+Lan Hui(1348141770)  How to solve the newly introduced "Blank Page" problem?
+
+Lan Hui(1348141770)  It turns out the solution is really simple.
+
+Lan Hui(1348141770)  Just tweak a conditional test a bit.
+
+Lan Hui(1348141770)  [图片]
+
+::
+
+    //  verify the hashed password and unhashed password
+    if(password_verify($password, $row["Password"]) or ($password = $row["Password"])){
+
+Lan Hui(1348141770)  Just relax the conditional test by adding an OR condition: ($password = $row["Password"]).
+
+Lan Hui(1348141770)  The variable $password stores the password you entered through the LRR web form.
+
+Lan Hui(1348141770)  $row["Password"] contains the pre-stored password which you entered during sign up.
+
+Lan Hui(1348141770)  Of course, they have to be equal before LRR would allow you in.
+
+Lan Hui(1348141770)  Then, you may ask, what is the point of having "password_verify($password, $row["Password"])"?
+
+Lan Hui(1348141770)  password_verify is a built-in function in PHP.
+
+Lan Hui(1348141770)  Well.
+
+Lan Hui(1348141770)  This function takes password stored in a human-readable form (e.g., 'secret'), hashes it and compares the hash result with the pre-stored password $row["Password"], which is also stored in a hash form.
+
+Lan Hui(1348141770)  Why bother with hash?
+
+Lan Hui(1348141770)  The point is that we, the software developers, do not want, or are not allowed to store users' password in a plain form.
+
+Lan Hui(1348141770)  By law we should not do that.
+
+Lan Hui(1348141770)  We should never, ever store users' password in a non-encrypted form because of risk of leak and the consequent liability.
+
+Lan Hui(1348141770)  Yahoo made that mistake a few years ago.
+
+Lan Hui(1348141770)  We must hash people's password by law.
+
+Lan Hui(1348141770)  For example, if my password is 'secret', then its hashed form, '2bb80d537b1da3e38bd30361aa855686bde0eacd7162fef6a25fe97bf527a25b', should be stored in our application.
+
+Lan Hui(1348141770)  Holy cow. Who can understand '2bb80d537b1da3e38bd30361aa855686bde0eacd7162fef6a25fe97bf527a25b' even if he gets that?
+
+Lan Hui(1348141770)  Here is a hash calculator that you can play with.
+
+Lan Hui(1348141770)  https://www.tools4noobs.com/online_tools/hash/
+
+Lan Hui(1348141770)  A great attribute of hash function is that it is a one-way function.
+
+Lan Hui(1348141770)  You cannot recover 'secret' from '2bb80d537b1da3e38bd30361aa855686bde0eacd7162fef6a25fe97bf527a25b'.
+
+Lan Hui(1348141770)  Therefore, even when '2bb80d537b1da3e38bd30361aa855686bde0eacd7162fef6a25fe97bf527a25b' is now in a bad guy's hands, it does not matter that much, since it will take him hundreds of thousands of years to get the 'secret'.
+
+Lan Hui(1348141770)  A wise bad man won't do that.
+
+Lan Hui(1348141770)  The additional OR conditional test is for backward compatibility.
+
+Lan Hui(1348141770)  A bit awkward.
+
+Lan Hui(1348141770)  Perhaps we can get rid of that conditional test in the future, to make the code simpler.
+
+Lan Hui(1348141770)  To do so, we need to hash all passwords that are stored in plain form.
+
+Lan Hui(1348141770)  Is it worth doing that?
+
+Lan Hui(1348141770)  We have more than 200 accounts now in LRR.
+
+Lan Hui(1348141770)  I think there is a programmable way to do that.
+
+Lan Hui(1348141770)  Anyway, that is future work.
+
+Lan Hui(1348141770)  Let us take a 5-minute break.
+
+Lan Hui(1348141770)  ===================================================
+
+Lan Hui(1348141770)  What have I learned from this improvement process?
+
+Lan Hui(1348141770)  Good software takes time.
+
+Lan Hui(1348141770)  LRR started in Fall 2018 as a graduate course project: http://lanlab.org/course/2018f/se/homepage.html 
+
+Lan Hui(1348141770)  One year and a half have passed.
+
+Lan Hui(1348141770)  Sustained efforts are required to build something that is really great so that people would pay to use it.
+
+Lan Hui(1348141770)  Sustained efforts require great focus and self-discipline.
+
+Lan Hui(1348141770)  You need at least 10 years of sustained efforts.
+
+Lan Hui(1348141770)  That is actually a rule of thumb in almost all areas of business.
+
+Lan Hui(1348141770)  But after 10 years, you will be good, earning billions of dollars a year.
+
+Lan Hui(1348141770)  Breathtakingly worthwhile.
+
+Lan Hui(1348141770)  That is about 100,000,000 dollars per year, for the previous ten years.
+
+Lan Hui(1348141770)  However, you need to lead a very frugal life in these 10 years with no guarantee of success.
+
+Lan Hui(1348141770)  Below is an article I want to share with you.
+
+Lan Hui(1348141770)  https://www.joelonsoftware.com/2001/07/21/good-software-takes-ten-years-get-used-to-it/
+
+Lan Hui(1348141770)  “The Oracle RDBMS has been around for 22 years now.  Windows NT development started 12 years ago.  Microsoft Word is positively long in the tooth; I remember seeing Word 1.0 for DOS in high school (that dates me, doesn’t it? It was 1983.)”
+
+Lan Hui(1348141770)  Look at QQ too - it started around 1998.
+
+Lan Hui(1348141770)  How many years have passed?
+
+Lan Hui(1348141770)  More than 20 years!
+
+Lan Hui(1348141770)  The current QQ is much better than the original QQ (which is a clone of OICQ).
+
+Lan Hui(1348141770)  I would say most people (who have not taken this course) don't know GOOD SOFTWARE TEAKS 10 YEARS.
+
+Lan Hui(1348141770)  Want to be a billionaire overnight?  No way.
+
+Lan Hui(1348141770)  Except Facebook.
+
+Lan Hui(1348141770)  Software is hard.  And hard things need time to polish.  As simple as that.
+
+Lan Hui(1348141770)  [图片]
+
+.. image:: lotus-note-user-pool.png
+   :height: 100
+   :alt:  number of installations of the Lotus Notes over the years
+
+
+Lan Hui(1348141770)  User pool of Lotus Notes.
+
+Lan Hui(1348141770)  It hit 55 million users in 1999.
+
+Lan Hui(1348141770)  55 million users means lots of money and a huge impact.
+
+Lan Hui(1348141770)  12 years have passed since 1.0.
+
+Lan Hui(1348141770)  Yet people have already spent 5 years to arrive at 1.0.
+
+Lan Hui(1348141770)  It is important to keep a healthy body as a programmer.
+
+Lan Hui(1348141770)  It takes very long time to be successful and you should enjoy that day when it arrives.
+
+Lan Hui(1348141770)  The problem of China software industry is exactly Lack of Time.
+
+Lan Hui(1348141770)  Desire of Success + Lack of Time = ???
+
+Lan Hui(1348141770)  Crap.
+
+Lan Hui(1348141770)  How much money has Oracle made?
+
+Lan Hui(1348141770)  Billions of dollars at least.
+
+Lan Hui(1348141770)  The Oracle database system was there in 1970's.
+
+Lan Hui(1348141770)  Joel Spolsky, the founder of Stack Overflow, is a prolific author good at writing.
+
+Lan Hui(1348141770)  He has produced more than 1000 blog posts over a period of 10 years.
+
+Lan Hui(1348141770)  He must have been thinking and thinking.
+
+Lan Hui(1348141770)  Writing is Thinking.  Writing is Communicating.
+
+Lan Hui(1348141770)  I think you should read his "Top 10" posts.
+
+Lan Hui(1348141770)  Let's take a 5-minute break.
+
+Lan Hui(1348141770)  After that we will talk about licenses.
+
+2020-03-09 17:01:19 Marie(2928285277)  Okay sir
+
+Lan Hui(1348141770)  ===================================================
+
+Lan Hui(1348141770)  One question.
+
+Lan Hui(1348141770)  What kind of free software license would you use if your software is an online application, i.e., you do not send people installation packages?
+
+Lan Hui(1348141770)  License for online applications, such as Simple Note, One Note.
+
+Lan Hui(1348141770)  Affero GPL.
+
+Lan Hui(1348141770)  Affero GPL has an extra clause designed specifically for online applications.
+
+Lan Hui(1348141770)  I think MIT is good too.  It is simple and permissive.
+
+Lan Hui(1348141770)  In contrast, GPL is a copyleft license, less permissive.
+
+Lan Hui(1348141770)  Copyleft is an interesting word.
+
+Lan Hui(1348141770)  The exact meaning of copyleft is that it requires all its derivative work to be copyleft too.
+
+Lan Hui(1348141770)  Some people think this is a way of defending freedom.
+
+Lan Hui(1348141770)  ===================================================
+
+Lan Hui(1348141770)  Quiz time.
+
+Lan Hui(1348141770)  This is limited-time quiz which you have to submit before 5:35pm today to LRR.
+
+Lan Hui(1348141770)
+
+::
+   
+   [True/False] Free software means zero-cost software.
+   [True/False] Zero-cost software cannot be proprietary.
+   [True/False] If the source code is visible, then the software is open source.
+   [True/False] Open source software cannot be used for commercial purposes.
+
+Lan Hui(1348141770)  Select two and only two to answer.
+
+2020-03-09 17:10:23 Marie(2928285277) I still can’t login to LRR
+
+2020-03-09 17:10:26 Guedalia Youma (3014432207) Where should we submit it ? By email ?
+
+Lan Hui(1348141770)  Bye.
+
+
 
 
 Friday, 13 March 2020