Comments on: A/B Technique for Web Application Deployment http://kylecordes.com/2007/web-app-swap Software, Business, and Life Tue, 20 Dec 2011 16:22:18 +0000 hourly 1 http://wordpress.org/?v=3.2.1 By: Jonathon P http://kylecordes.com/2007/web-app-swap/comment-page-1#comment-26507 Jonathon P Tue, 14 Oct 2008 19:32:16 +0000 http://kylecordes.com/2007/01/20/web-app-swap/#comment-26507 ""# Hani Says: January 22nd, 2007 at 8:14 am This is fine for simple updates where you can have the two versions (a and b) of your application running. What happens if the update to your application actually changes things like your database schema, making running both A and B impossible?" What happened to running both programs parallel until you get everyone trained and up and running. I guess I am too old school. “”# Hani Says:
January 22nd, 2007 at 8:14 am

This is fine for simple updates where you can have the two versions (a and b) of your application running. What happens if the update to your application actually changes things like your database schema, making running both A and B impossible?”

What happened to running both programs parallel until you get everyone trained and up and running. I guess I am too old school.

]]> By: dmitry http://kylecordes.com/2007/web-app-swap/comment-page-1#comment-1306 dmitry Fri, 26 Jan 2007 19:38:48 +0000 http://kylecordes.com/2007/01/20/web-app-swap/#comment-1306 what's the "empty cache" problem? I have a vague feeling for what it is, but would like to read more about it. Any references? thanks. what’s the “empty cache” problem? I have a vague feeling for what it is, but would like to read more about it. Any references? thanks.

]]> By: Nikodem http://kylecordes.com/2007/web-app-swap/comment-page-1#comment-1292 Nikodem Thu, 25 Jan 2007 17:29:19 +0000 http://kylecordes.com/2007/01/20/web-app-swap/#comment-1292 I used similar approach as described in the response to Hani's question. Instead of A/B Technique it might be called A/B/C Technique. A - Old version of the web application and old DB schema B1 - Version of the web app which can handle the old schema and the new schema together with O L D DB schema B2 - Version of the web app which can handle the old schema and the new schema together with N E W DB schema C - New web app together with new DB schema. Many times the DB changes are just extensions to the existing schema and old version of a web app work with it without problems. I used similar approach as described in the response to Hani’s question. Instead of A/B Technique it might be called A/B/C Technique.
A – Old version of the web application and old DB schema
B1 – Version of the web app which can handle the old schema and the new schema together with O L D DB schema
B2 – Version of the web app which can handle the old schema and the new schema together with N E W DB schema
C – New web app together with new DB schema.
Many times the DB changes are just extensions to the existing schema and old version of a web app work with it without problems.

]]> By: Creigh http://kylecordes.com/2007/web-app-swap/comment-page-1#comment-1267 Creigh Tue, 23 Jan 2007 06:28:09 +0000 http://kylecordes.com/2007/01/20/web-app-swap/#comment-1267 Still, there are things that will have to be duplicated, like static xml xsl (besides dbase schema changes). Im not sure I would want to mantain all that. Besides, my version A is sitting in cvs under an old tag. I think its a good idea and had some similar ideas along the way. I also like the fact that it keeps environments steady. If B fails in a prod environment then you can revert back to A with min impact. I dont know if its worth redesigning our (complex) deployment proccess just for that though. Still, there are things that will have to be duplicated, like static xml xsl (besides dbase schema changes). Im not sure I would want to mantain all that. Besides, my version A is sitting in cvs under an old tag. I think its a good idea and had some similar ideas along the way. I also like the fact that it keeps environments steady. If B fails in a prod environment then you can revert back to A with min impact. I dont know if its worth redesigning our (complex) deployment proccess just for that though.

]]> By: kyle http://kylecordes.com/2007/web-app-swap/comment-page-1#comment-1266 kyle Mon, 22 Jan 2007 15:29:06 +0000 http://kylecordes.com/2007/01/20/web-app-swap/#comment-1266 Good question, Hani. I added a new section to the post to explain this. The short answer is that if the need is there and the budget is there, you can make nearly any kind of upgrade (possibly as a series of steps) without ever turning a whole system off. Good question, Hani. I added a new section to the post to explain this. The short answer is that if the need is there and the budget is there, you can make nearly any kind of upgrade (possibly as a series of steps) without ever turning a whole system off.

]]> By: Hani http://kylecordes.com/2007/web-app-swap/comment-page-1#comment-1265 Hani Mon, 22 Jan 2007 15:14:12 +0000 http://kylecordes.com/2007/01/20/web-app-swap/#comment-1265 This is fine for simple updates where you can have the two versions (a and b) of your application running. What happens if the update to your application actually changes things like your database schema, making running both A and B impossible? This is fine for simple updates where you can have the two versions (a and b) of your application running. What happens if the update to your application actually changes things like your database schema, making running both A and B impossible?

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