# About Akka gRPC

**URL:** <https://discuss.akka.io/t/about-akka-grpc/10218>\
**Category:** Akka gRPC\
**Tags:** java\
**Created:** [March 10, 2023, 12:35am UTC](https://discuss.akka.io/t/about-akka-grpc/10218 "2023-03-10T00:35:32Z")\
**Posts on this page:** 7\
**Page:** 1

<div class="post-metadata">

**Author:** ![watimuma](https://sea2.discourse-cdn.com/flex020/user_avatar/discuss.akka.io/watimuma/32/2947_2.png) [@watimuma](https://discuss.akka.io/u/watimuma)\
**Post date:** [March 10, 2023, 12:35am UTC](https://discuss.akka.io/t/about-akka-grpc/10218/1 "2023-03-10T00:35:32Z")

</div>

Hi~  
I’m trying to use Akka-gRPC .First , I flow the guide [Server](https://doc.akka.io/docs/akka-grpc/current/server/walkthrough.html) .  
My development environment:

```auto
JDK 11.0.16

Maven configuration:
<properties>
        <maven.compiler.source>1.8</maven.compiler.source>
        <maven.compiler.target>1.8</maven.compiler.target>
        <akka.grpc.version>2.3.0</akka.grpc.version>
        <grpc.version>1.48.1</grpc.version>
        <project.encoding>UTF-8</project.encoding>
    </properties>
    <dependencies>
        <dependency>
            <groupId>com.lightbend.akka.grpc</groupId>
            <artifactId>akka-grpc-runtime_2.12</artifactId>
            <version>${akka.grpc.version}</version>
        </dependency>

        <dependency>
            <groupId>com.google.protobuf</groupId>
            <artifactId>protobuf-java</artifactId>
            <version>3.21.9</version>
        </dependency>
        <dependency>
            <groupId>com.thesamet.scalapb</groupId>
            <artifactId>scalapb-runtime_2.12</artifactId>
            <version>0.11.11</version>
        </dependency>
        <dependency>
            <groupId>com.typesafe.akka</groupId>
            <artifactId>akka-discovery_2.12</artifactId>
            <version>2.7.0</version>
        </dependency>
        <dependency>
            <groupId>com.typesafe.akka</groupId>
            <artifactId>akka-http-core_2.12</artifactId>
            <version>10.5.0-M1</version>
        </dependency>
        <dependency>
            <groupId>com.typesafe.akka</groupId>
            <artifactId>akka-http_2.12</artifactId>
            <version>10.5.0-M1</version>
        </dependency>
        <dependency>
            <groupId>com.typesafe.akka</groupId>
            <artifactId>akka-stream_2.12</artifactId>
            <version>2.7.0</version>
        </dependency>
        <dependency>
            <groupId>io.grpc</groupId>
            <artifactId>grpc-core</artifactId>
            <version>1.48.1</version>
        </dependency>
        <dependency>
            <groupId>io.grpc</groupId>
            <artifactId>grpc-netty-shaded</artifactId>
            <version>1.48.1</version>
        </dependency>
        <dependency>
            <groupId>io.grpc</groupId>
            <artifactId>grpc-protobuf</artifactId>
            <version>1.48.1</version>
        </dependency>
        <dependency>
            <groupId>org.scala-lang</groupId>
            <artifactId>scala-library</artifactId>
            <version>2.12.17</version>
        </dependency>
    </dependencies>
    <build>
        <plugins>
            <plugin>
                <groupId>com.lightbend.akka.grpc</groupId>
                <artifactId>akka-grpc-maven-plugin</artifactId>
                <version>${akka.grpc.version}</version>
                <executions>
                    <execution>
                        <goals>
                            <goal>generate</goal>
                        </goals>
                    </execution>
                </executions>
            </plugin>
        </plugins>
    </build>

proto file : src/main/java/proto/helloworld.proto 

```

When I use “mvn akka-grpc:generate” command , the problem is

```auto
[WARNING] Error injecting: akka.grpc.maven.GenerateMojo
java.lang.NoClassDefFoundError: scala/math/Ordering
    at java.lang.Class.getDeclaredConstructors0 (Native Method)
    at java.lang.Class.privateGetDeclaredConstructors (Class.java:3137)
    at java.lang.Class.getDeclaredConstructors (Class.java:2357)
    at com.google.inject.spi.InjectionPoint.forConstructorOf (InjectionPoint.java:245)
    at com.google.inject.internal.ConstructorBindingImpl.create (ConstructorBindingImpl.java:115)
    at com.google.inject.internal.InjectorImpl.createUninitializedBinding (InjectorImpl.java:706)
    at com.google.inject.internal.InjectorImpl.createJustInTimeBinding (InjectorImpl.java:930)
    at com.google.inject.internal.InjectorImpl.createJustInTimeBindingRecursive (InjectorImpl.java:852)
    at com.google.inject.internal.InjectorImpl.getJustInTimeBinding (InjectorImpl.java:291)
    at com.google.inject.internal.InjectorImpl.getBindingOrThrow (InjectorImpl.java:222)
    at com.google.inject.internal.InjectorImpl.getProviderOrThrow (InjectorImpl.java:1040)
    at com.google.inject.internal.InjectorImpl.getProvider (InjectorImpl.java:1071)
    at com.google.inject.internal.InjectorImpl.getProvider (InjectorImpl.java:1034)
    at com.google.inject.internal.InjectorImpl.getInstance (InjectorImpl.java:1086)
    at org.eclipse.sisu.space.AbstractDeferredClass.get (AbstractDeferredClass.java:48)
    at com.google.inject.internal.ProviderInternalFactory.provision (ProviderInternalFactory.java:85)
    at com.google.inject.internal.InternalFactoryToInitializableAdapter.provision (InternalFactoryToInitializableAdapter.java:57)
    at com.google.inject.internal.ProviderInternalFactory$1.call (ProviderInternalFactory.java:66)
    at com.google.inject.internal.ProvisionListenerStackCallback$Provision.provision (ProvisionListenerStackCallback.java:112)
    at org.eclipse.sisu.bean.BeanScheduler$CycleActivator.onProvision (BeanScheduler.java:230)
    at com.google.inject.internal.ProvisionListenerStackCallback$Provision.provision (ProvisionListenerStackCallback.java:120)
    at com.google.inject.internal.ProvisionListenerStackCallback.provision (ProvisionListenerStackCallback.java:66)
    at com.google.inject.internal.ProviderInternalFactory.circularGet (ProviderInternalFactory.java:61)
    at com.google.inject.internal.InternalFactoryToInitializableAdapter.get (InternalFactoryToInitializableAdapter.java:47)
    at com.google.inject.internal.ProviderToInternalFactoryAdapter.get (ProviderToInternalFactoryAdapter.java:40)
    at com.google.inject.internal.SingletonScope$1.get (SingletonScope.java:168)
    at com.google.inject.internal.InternalFactoryToProviderAdapter.get (InternalFactoryToProviderAdapter.java:39)
    at com.google.inject.internal.InjectorImpl$1.get (InjectorImpl.java:1050)
    at org.eclipse.sisu.inject.LazyBeanEntry.getValue (LazyBeanEntry.java:81)
    at org.eclipse.sisu.plexus.LazyPlexusBean.getValue (LazyPlexusBean.java:51)
    at org.codehaus.plexus.DefaultPlexusContainer.lookup (DefaultPlexusContainer.java:263)
    at org.codehaus.plexus.DefaultPlexusContainer.lookup (DefaultPlexusContainer.java:255)
    at org.apache.maven.plugin.internal.DefaultMavenPluginManager.getConfiguredMojo (DefaultMavenPluginManager.java:520)
    at org.apache.maven.plugin.DefaultBuildPluginManager.executeMojo (DefaultBuildPluginManager.java:124)
    at org.apache.maven.lifecycle.internal.MojoExecutor.execute (MojoExecutor.java:210)
    at org.apache.maven.lifecycle.internal.MojoExecutor.execute (MojoExecutor.java:156)
    at org.apache.maven.lifecycle.internal.MojoExecutor.execute (MojoExecutor.java:148)
    at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject (LifecycleModuleBuilder.java:117)
    at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject (LifecycleModuleBuilder.java:81)
    at org.apache.maven.lifecycle.internal.builder.singlethreaded.SingleThreadedBuilder.build (SingleThreadedBuilder.java:56)
    at org.apache.maven.lifecycle.internal.LifecycleStarter.execute (LifecycleStarter.java:128)
    at org.apache.maven.DefaultMaven.doExecute (DefaultMaven.java:305)
    at org.apache.maven.DefaultMaven.doExecute (DefaultMaven.java:192)
    at org.apache.maven.DefaultMaven.execute (DefaultMaven.java:105)
    at org.apache.maven.cli.MavenCli.execute (MavenCli.java:957)
    at org.apache.maven.cli.MavenCli.doMain (MavenCli.java:289)
    at org.apache.maven.cli.MavenCli.main (MavenCli.java:193)
    at jdk.internal.reflect.NativeMethodAccessorImpl.invoke0 (Native Method)
    at jdk.internal.reflect.NativeMethodAccessorImpl.invoke (NativeMethodAccessorImpl.java:62)
    at jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke (DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke (Method.java:566)
    at org.codehaus.plexus.classworlds.launcher.Launcher.launchEnhanced (Launcher.java:282)
    at org.codehaus.plexus.classworlds.launcher.Launcher.launch (Launcher.java:225)
    at org.codehaus.plexus.classworlds.launcher.Launcher.mainWithExitCode (Launcher.java:406)
    at org.codehaus.plexus.classworlds.launcher.Launcher.main (Launcher.java:347)
    at org.codehaus.classworlds.Launcher.main (Launcher.java:47)

```

Please,how to solve it . Wait your reply 😄

---

<div class="post-metadata">

**Author:** ![johanandren](https://sea2.discourse-cdn.com/flex020/user_avatar/discuss.akka.io/johanandren/32/85_2.png) [@johanandren](https://discuss.akka.io/u/johanandren)\
**Post date:** [March 10, 2023, 7:43am UTC](https://discuss.akka.io/t/about-akka-grpc/10218/2 "2023-03-10T07:43:23Z")

</div>

Can you try and see if the quickstart maven project compiles as expected? [Akka gRPC Quickstart with Java · Lightbend Tech Hub](https://developer.lightbend.com/guides/akka-grpc-quickstart-java/)

---

<div class="post-metadata">

**Author:** ![watimuma](https://sea2.discourse-cdn.com/flex020/user_avatar/discuss.akka.io/watimuma/32/2947_2.png) [@watimuma](https://discuss.akka.io/u/watimuma)\
**Post date:** [March 10, 2023, 8:02am UTC](https://discuss.akka.io/t/about-akka-grpc/10218/3 "2023-03-10T08:02:44Z")

</div>

Because the sample project failed to compile ,so I want to follow the document once

---

<div class="post-metadata">

**Author:** ![johanandren](https://sea2.discourse-cdn.com/flex020/user_avatar/discuss.akka.io/johanandren/32/85_2.png) [@johanandren](https://discuss.akka.io/u/johanandren)\
**Post date:** [March 10, 2023, 8:13am UTC](https://discuss.akka.io/t/about-akka-grpc/10218/4 "2023-03-10T08:13:57Z")

</div>

So the quickstart fails as well? I wonder because if the quickstart maven project works fine we could compare the pom.xml here to yours and perhaps see how they differ.

---

<div class="post-metadata">

**Author:** ![watimuma](https://sea2.discourse-cdn.com/flex020/user_avatar/discuss.akka.io/watimuma/32/2947_2.png) [@watimuma](https://discuss.akka.io/u/watimuma)\
**Post date:** [March 14, 2023, 6:16am UTC](https://discuss.akka.io/t/about-akka-grpc/10218/5 "2023-03-14T06:16:26Z")

</div>

en…I’m start from quickstart , when I execute akka-grpc:generate it prompt the same error message .  
Then, I installed protoc of version libprotoc 3.21.9 ,and use command “protoc --java\_out . helloworld.proto” ,but some class not found : GreeterServiceClient ,GreeterServiceHandlerFactory,GreeterService .

---

<div class="post-metadata">

**Author:** ![johanandren](https://sea2.discourse-cdn.com/flex020/user_avatar/discuss.akka.io/johanandren/32/85_2.png) [@johanandren](https://discuss.akka.io/u/johanandren)\
**Post date:** [March 14, 2023, 8:10am UTC](https://discuss.akka.io/t/about-akka-grpc/10218/6 "2023-03-14T08:10:13Z")

</div>

That’s unfortunate.

Akka gRPC does not rely on a local installation of protobuf but pulls it in via a maven dependency so that local libprotoc version is not needed and should not matter.

Just to doublecheck there was no regression I pulled the quickstart and built it, without problems, so not sure what is the cause of the problems you are having.

What OS and Java version are you using? I see lines for eclipse in your original stacktrace, are you triggering maven through Eclipse, and if so, could you try the same via the command line and see if it works there?

---

<div class="post-metadata">

**Author:** ![watimuma](https://sea2.discourse-cdn.com/flex020/user_avatar/discuss.akka.io/watimuma/32/2947_2.png) [@watimuma](https://discuss.akka.io/u/watimuma)\
**Post date:** [March 15, 2023, 8:19am UTC](https://discuss.akka.io/t/about-akka-grpc/10218/7 "2023-03-15T08:19:04Z")

</div>

OS:Windows 10 21H2  
jdk:JDK 11.0.16

I’ll try to deal with this problem again.