Re: Deploy to Google App Engine (GAE)

Afaik gwt:devmode is launching  a GWT Jetty, rather than the GAE Jetty.
The latter requires appengine:run
with a launch profile env property & name
appengine:run -Denv=haslistener

As you say: for IDE debugging: we need a Remote Java Application & jvmFlags, discussed at length here:

https://stackoverflow.com/questions/138511/what-are-java-command-line-options-to-set-to-allow-jvm-to-be-remotely-debugged
someone says:
For Java 5 and above, run it with:
-agentlib:jdwp=transport=dt_socket,server=y,suspend=n,address=1044
rather than
Xrunjdwp:transport=dt_socket,address=1044,server=y,suspend=n
I havent tried this yet.

With this setup the dev GAE server uses the cloud datastore (& blobstore I think).
To fix, in the gloud CLI app run:
gcloud components install cloud-datastore-emulator
If you didnt install beta commands, it will prompt for that.
cloud-datastore-emulator 2.3.1
before launch of GAE server run:
gcloud beta emulators datastore start --project='prjname' --host-port=localhost:8081 --data-dir=C:\Users\tim_m\eclipse-workspace\Snptn\Snptn-server\src\main\webapp

Set environment variable in the eclipse launch to attach this DATASTORE_EMULATOR environment
Last time I looked: the local datastore viewer cant show objectify entities, only blobstore files.

Re  copying src/main/webapp files to the target folder: afaik that is done by
maven-jar-plugin jar goal (jar:jar) which is invoked by calling package (phase)
 
Btw I often read that the tbroyer multi-project pattern is better because it keeps server & client dependencies separated, but its a more complex pattern.
Re the poms I attached here: 1 problem is inconsistencies in:
    <!-- To define the plugin version in your parent POM -->
    <pluginManagement>

    <!-- To use the plugin goals in your POM or parent POM -->
    <plugins>

On Saturday, December 23, 2023 at 7:35:42 AM UTC Craig Mitchell wrote:

Managed to get server debugging working by adding:

<jvmArg>-Xrunjdwp:transport=dt_socket,server=y,suspend=y,address=5005</jvmArg>

to the gwt-maven-plugin.

And then creating a Remote JVM Debug launcher in IntelliJ (on port 5005), that I run after running gwt:devmode.

I'm surprised IntelliJ can't just automatically attach to the running server.  Is this what everyone does that uses gwt:devmode?

On Saturday 23 December 2023 at 3:28:36 pm UTC+11 Craig Mitchell wrote:

Thanks Tim!  Looking at your POM files, I see I missed adding:

<outputDirectory>${project.build.directory}/${project.artifactId}-${project.version}/WEB-INF/classes</outputDirectory>

I also needed to:

• Convert all my servlets to @WebServlet (as the GWT Jetty server didn't pick up my web.xml like the GAE server used to).
• Give the GWT plugin the JVM arg "--add-opens java.base/java.lang=ALL-UNNAMED" for execeptions to be returned to the client.

Strangely, Maven isn't copying my src/main/webapp files to the target folder, so I'm doing that manually with the maven-resources-plugin.

So now GWT starts, dev compiles (including source maps), and runs beautifully, including RPC calls.  Java17 runtime with a Java11 source level.  Happy days!  New POM attached.

I've switched from using Eclipse to IntelliJ (because I no longer will be using any of the Eclipse plugins, and wanted a fresh start).  However, debugging my server never hits the breakpoints.

Do you use IntelliJ, do we need any special params to enable debug?

I'm yet to get Google App Engine to work.  When I try to access any of the GAE calls, I just get "No API environment is registered for this thread.".  I think I need to setup the enviroment somehow now I no longer have a GAE server.

Cheers!

On Friday 22 December 2023 at 4:41:07 am UTC+11 tim_mac...@yahoo.co.uk wrote:

These are my current poms, based on the tbroyer archetype.

Probably best to look at the latter first if youre not familiar with it.

The launch is configured in the server pom:

    <profile>
      <id>env-dev-gae1</id>
      <activation>
        <property>  
          <name>env</name>
          <value>haslistener</value>

...

      <build>                    
        <pluginManagement>
          ...

              <groupId>com.google.cloud.tools</groupId>
              <artifactId>appengine-maven-plugin</artifactId>

A version of Jetty is attached by the appengine-maven-plugin config here (afaik)

The eclipse launch goal is: appengine:run -Denv=haslistener

Re GWT 2.10 : it can use JRE 17 but can only compile Java 11 source, iirc.

Poms are a bit messy but should help if you want to take this approach

On Thursday, December 21, 2023 at 11:36:51 AM UTC Craig Mitchell wrote:

Forgot to mention.  My target is Java 17, but my source is Java 1.8.

So:

<properties>

<maven.compiler.source>1.8</maven.compiler.source>
<maven.compiler.target>17</maven.compiler.target>
</properties>

And:

<pluginManagement>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-compiler-plugin</artifactId>
<version>3.11.0</version>
<configuration>
<source>${maven.compiler.source}</source>
<target>${maven.compiler.target}</target>
</configuration>
</plugin>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-resources-plugin</artifactId>
<version>3.3.1</version>
</plugin>
</plugins>
</pluginManagement>

I've attached my current POM (which isn't working, so don't copy it 🙂), but if you can see my mistake, please let me know.

Thanks again!

On Thursday 21 December 2023 at 10:27:01 pm UTC+11 Craig Mitchell wrote:

Hi Tim,

I thought GWT 2.10.0 supported Java17.  From the release notes:   https://www.gwtproject.org/release-notes.html#Release_Notes_2_10_0

Tested support for running on Java 17, dropped remaining support for running on Java 7.

I'm also using appengine-maven-plugin 2.5.0.

<plugin>
<groupId>com.google.cloud.tools</groupId>
<artifactId>appengine-maven-plugin</artifactId>
<version>2.5.0</version>
<configuration>
<projectId>headtoheaddrifting</projectId>
<version>GCLOUD_CONFIG</version>
</configuration>
</plugin>

Along with GWT plugin:

<plugin>
<groupId>net.ltgt.gwt.maven</groupId>
<artifactId>gwt-maven-plugin</artifactId>
<version>1.1.0</version>
<extensions>true</extensions>
<configuration>
<moduleName>team.drift.DriftTeam</moduleName>
<moduleShortName>dt</moduleShortName>
<packaging>gwt-lib</packaging>
<launcherDir>${project.build.directory}/gwt/launcherDir</launcherDir>
<warDir>${project.build.directory}/drift-team-1.0-SNAPSHOT</warDir>
<startupUrls>
<startupUrl>index.html</startupUrl>
</startupUrls>
</configuration>
</plugin>

Running: "mvn gwt:devmode" I can get it to start the Jetty server and GWT code server.  It finds my project, but currently, when opening the browser it says:

HTTP ERROR 503 Service Unavailable
URI: /index.html
STATUS: 503
MESSAGE: Service Unavailable
SERVLET: -

I put my web assets in  src/main/webapp  and I don't think it's seeing them.  Plus I don't think it's seeing my web.xml that's in  src/main/webapp/WEB-INF/web.xml

Maybe they need to be copied to the target directory or somewhere, or the GWT plugin pointed to where they are somehow.  Not sure.  Any help is greatly appreaciated.

On Thursday 21 December 2023 at 4:06:46 am UTC+11 tim_mac...@yahoo.co.uk wrote:

I havent tried raising the Java level yet, its still  JavaSE-1.8.
Got as far as using latest versions:
JDK 21
gcloud CLI app & cloudSdkVersion  457.0.0
appengine-maven-plugin 2.5.0

To get it to run, so far:
1 I had to remove all DOCTYPE declarations in xml files in the server project (new restrictions on DTD)
2 appengine-maven-plugin 2.5.0 requires:
                <configuration>
                    <jvmFlags>
                        <item>--add-opens</item>
                <item>java.base/java.util=ALL-UNNAMED</item>
This stops 500 Server Error which I've not seen before:
GCLOUD: java.lang.reflect.InaccessibleObjectException:
Unable to make field accessible: module java.base does not "opens java.util" to unnamed module @2c95ac9e

So Craig, you say with Java17 on GAE, there isn't a web server included anymore.
So this has to be defined somewhere in  appengine-maven-plugin ?
The minimum level to avoid being shut down on GAE standard is >8
& 11 is the max for GWT, so that would seem do for now, why Java 17  ?

On Wednesday, December 20, 2023 at 4:46:03 AM UTC Craig Mitchell wrote:

No worries not posting the POMs Tim.

The bit I'm struggling with, the old Java 8 version had its own GAE server.  So I would run that, and a GWT Code Server.  Easy!

btw: I'm talking about GAE Standard.  GAE Flexible you can do whatever you want, but that's more work and more expensive.

Now with the upgrade to Java17 on GAE, there isn't a web server included anymore.  It's up to you to supply one.  I would assume when you deploy it, it doesn't actually use your server, but what setup is GAE expecting for the deploy?

I see there is a SpringBoot GAE example, so it might be easier to use that, and get GWT to work with SpringBoot.  Not sure.  Very interested to hear what you're doing.

Thanks!

On Wednesday 20 December 2023 at 1:51:55 pm UTC+11 tim_mac...@yahoo.co.uk wrote:

For some years I've been deploying GWT 2.8.2 to GAE with Maven & Google Cloud Tools.
I now find GAE is not supporting Java 8 after January, so currently upgrading (rather slowly).
There are 4 long POM files,  probably better to mail them then post a distilled version here ?

On Sunday, December 17, 2023 at 5:20:56 AM UTC Craig Mitchell wrote:

Hi,

The instructions here https://www.gwtproject.org/doc/latest/tutorial/appengine.html are no longer valid, as the Google Plugin for Eclipse is now dead (Google no longer supports Java 1.8, and the Google Plugin for Eclipse doesn't support any Eclipse versions that support anything after Java 1.8).  Ref:  https://github.com/GoogleCloudPlatform/google-cloud-eclipse/issues/3710

The new approach with GAE is to use Maven or Gradle with Google Cloud Tools.

I've been struggling to work out how this is supposed to happen.  It looks like we now have to provide our own Web Server for GAE, but can we use the Jetty server that GWT uses for development?  I assume the deploy build would not include the Jetty web server?

If anyone has deployed a GWT app to GAE with Maven and the new Google Cloud Tools, it would be great if you could give high level instructions on how it's all supposed to fit together.

An example Maven POM file with both the Google Cloud Tools, and GWT would be even better.  🙂

Thanks!

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