JBossDeveloper

The old mechanism had its problems but it cannot be outrightly dismissed saying it was broken. It's been in use for a decade and it was one of the key features of JBoss (drag&drop an archive to hotdeploy it, remove to undeploy), a feature that everybody loved and all our competitors copied. Hundrends of thousands of users are already familiar with it. Remember also farming, a mechanism that had even more problems than hotdeployment? We removed it at one point and then we had to add it back because customers liked it no matter how many problems it had.

Just to address these two points:

Vendors did not carbon copy this feature due to the problems. None of them support hot exploded directories the way jboss does. They either out right disallow them, or support the usage only at startup. They either provide a way for you to drop in a marker to force redeploy, or provide some kind of tool/api to trigger it.

Farming was resurrected because we had no reasonable alternative.

Brian Stansberry wrote:

 

Here's what I'm doing. Following uses the term "auto-deploy" to refer to the scanner deciding to deploy without being told to via a .dodeploy marker.

 

-snip-

Excellent. Now this is an approach I can get behind.

2) Reliable auto-deploy of exploded content is not possible.

We may in the future be able to support it somewhat reliably using FS events, but not without native code (or NIO2 in JDK7):

http://jpathwatch.wordpress.com/

It would require a well tested algorithm, and it would not have uniform portability.

Brian Stansberry wrote:

 

Here's what I'm doing. Following uses the term "auto-deploy" to refer to the scanner deciding to deploy without being told to via a .dodeploy marker.

 

1) I'm adding the zip scanning Jason mentioned to detect whether the zip is complete. This is the basis for reliable auto-deploy of zipped content.

 

2) Reliable auto-deploy of exploded content is not possible. As a safety aid I will use the scanning code from 1) to check any nested jars, but that doesn't make it reliable.

 

3) If auto-deploy is available for a type of content, a .skipdeploy marker will prevent auto-deploy of a particular file.

 

3) I'm going to add an "auto-deploy" flag to the deployment-scanner element, with legal values "ALL", "ZIPPED", "NONE". Flag controls what types of content auto-deploy behavior is enabled for. Per Jason's statement above, default is "ZIPPED", as "ALL" cannot be made reliable. Configuring "ALL" will result in a WARN message in the server log.

 

4) For auto-deploy of exploded content, there will be no deployment descriptor file timestamp check as the means of detecting the need to redeploy, as in EE 6 there is no universal requirement for deployment descriptors. And checking the directory timestamp is not valid as it's easy to change content without triggering a change in the directory timestamp. So, with auto-deploy if any file in the deployment changes, the deployment gets redeployed. People who want to change content without triggering redeploy are going to have to use marker files; either leave auto-deploy disabled and use .dodeploy, or enable auto-deploy and use .skipdeploy.

 

5) If a scan tries to use auto-deploy for a file and detects incomplete content, the scan will be aborted (i.e. it will be as if no changes were detected.) The next time the scanner runs, it will check again.

 

 

Sounds good!

One final question:

2) Reliable auto-deploy of exploded content is not possible. As a safety aid I will use the scanning code from 1) to check any nested jars, but that doesn't make it reliable.

So triggering a deployment of exploded content (with the auto-deploy flag set to ZIPPED) would require a .dodeploy marker right? I have no issues with using a marker for this specific case - just want to understand the expected behaviour.

jaikiran pai wrote:

 

One final question:

 

2) Reliable auto-deploy of exploded content is not possible. As a safety aid I will use the scanning code from 1) to check any nested jars, but that doesn't make it reliable.

So triggering a deployment of exploded content (with the auto-deploy flag set to ZIPPED) would require a .dodeploy marker right? I have no issues with using a marker for this specific case - just want to understand the expected behaviour.

I think Brian meant a .dodeploy marker will be needed if the setting is NONE. If the setting is ZIPPED it will look for a change in any nested zipped archive.

BTW, thanks guys for looking into this.

Jason Greene wrote:

 

The old mechanism had its problems but it cannot be outrightly dismissed saying it was broken. It's been in use for a decade and it was one of the key features of JBoss (drag&drop an archive to hotdeploy it, remove to undeploy), a feature that everybody loved and all our competitors copied. Hundrends of thousands of users are already familiar with it. Remember also farming, a mechanism that had even more problems than hotdeployment? We removed it at one point and then we had to add it back because customers liked it no matter how many problems it had.

Just to address these two points:

 

Vendors did not carbon copy this feature due to the problems. None of them support hot exploded directories the way jboss does. They either out right disallow them, or support the usage only at startup. They either provide a way for you to drop in a marker to force redeploy, or provide some kind of tool/api to trigger it.

 

Farming was resurrected because we had no reasonable alternative.

Last time I tried tomcat it supported both zipped and exploded hot deployment - and Glassfish likewise. What competition do you refer to ?

Also since I am replying again, I just want to mention that windows hasn't defaulted to diaplaying 3 char extensions in a long long time. In fact I would argue that java 6 probably doesn't even support these versions.

Just to be clear, the issue about having the first characters be "unique" were not at all about Windows/DOS 3 char extension display.

It was Brian and me going through the state changes on a machine at Devoxx and viewing it from a file browser (i.e. Explorer and Finder) and noticing that the UI's by default were showing ".dep.." and ".dep..." when we were using .deploy and .deployed as the markers.

That's why it was suggested - not because of ancient OS reasons.

Max Rydahl Andersen wrote:

 

Last time I tried tomcat it supported both zipped and exploded hot deployment - and Glassfish likewise. What competition do you refer to ?

Glassfish uses a .redeploy marker. It is true that Tomcat is the closest to JBoss, but it also doesn't implement non-war deployments.

I go on a small trip and this thread goes wild - sorry for being late to the "party".

 

1) I'm adding the zip scanning Jason mentioned to detect whether the zip is complete. This is the basis for reliable auto-deploy of zipped content.

Great - makes perfect sense.

2) Reliable auto-deploy of exploded content is not possible. As a safety aid I will use the scanning code from 1) to check any nested jars, but that doesn't make it reliable.

Okey...not sure if it will worth the hassle/CPU-cycles but worth experimenting with.

 

3) If auto-deploy is available for a type of content, a .skipdeploy marker will prevent auto-deploy of a particular file.

..particular file or directory, right ?

btw. I really like this "veto" option Much easier to implement from user/tooling perspective.

3) I'm going to add an "auto-deploy" flag to the deployment-scanner element, with legal values "ALL", "ZIPPED", "NONE". Flag controls what types of content auto-deploy behavior is enabled for. Per Jason's statement above, default is "ZIPPED", as "ALL" cannot be made reliable. Configuring "ALL" will result in a WARN message in the server log.

Just to be sure I understand this correctly - this means by default AS7

cp -r foo.war AS7/deployments

will trigger an deployment of foo.war when it is an archive when the scanner sees the war and it is complete.

it will *not* trigger deployment of foo.war when it is a directory. Correct ?

4) For auto-deploy of exploded content, there will be no deployment descriptor file timestamp check as the means of detecting the need to redeploy, as in EE 6 there is no universal requirement for deployment descriptors. And checking the directory timestamp is not valid as it's easy to change content without triggering a change in the directory timestamp. So, with auto-deploy if any file in the deployment changes, the deployment gets redeployed. People who want to change content without triggering redeploy are going to have to use marker files; either leave auto-deploy disabled and use .dodeploy, or enable auto-deploy and use .skipdeploy.

It took me a couple of reads of #3 and #4 to get what this meant but this actually makes perfect sense and gives a good balance

between preventing bad deployments and still have incremental updates of your exploded content.

This basically means the *only* new thing by default is having to do a

touch foo.war.dodeploy

or the more portable:

echo > foo.war.dodeploy

for exploded directories. Everything else is just as "before" but better

i.e. to make it clean its important that if you detect both a complete foo.war and a foo.war.dodeploy the .dodeploy still gets deleted and goes through the transitions; and that there will be a .deployed file no matter what triggered the deploy.

 

5) If a scan tries to use auto-deploy for a file and detects incomplete content, the scan will be aborted (i.e. it will be as if no changes were detected.) The next time the scanner runs, it will check again.

Perfect from first read, but i'm still curious how long that consistency check will take for large projects ?

And should there be a maximum of redeployment attempts to avoid the logs for filling/cpu cycles burning ?

Maybe have the user made aware of the .dodeploy failing and make it a .deployfailed after some time and thus require a new touch ?

(should be fine since if user is doing .dodeploy we should assume that the deployment is actually expected to be complete?)

AFAICT, this is essentially completing what was discussed in Antwerp and detailed a few pages back by Max. Difference is auto-deploy of exploded content will not be default behavior.

Yes, this works for me   I basically get all the goodies I wished for.

Sorry for coming up with a user question here, but I observe a "strange" behavior with auto deployment: I copied an EAR file to the "standalone\deployments" directory (using a JBoss picked from GIT two hours ago). Deployment fails and a "..ear.failed" file is created.

So I tried to "undeploy" the app by killing the "...ear.failed" file. But this resulted in a undeploy and redeploy of the EAR (with another failure of course).

Is this the expected behaviour? In case of an error, is it possible to just delete the EAR file and the "ear.failed" file to remove the app from the server?

If yes, it would be worth to add this to "README.txt" ;-).

Best regards

Wolfgang