Pass and call lambdas on the server and drop docker / deploy / ...

When developing a client-server application, I always have a question, but how will I deploy it on the server, pack it in jar / war / docker after writing the code, and then still need to transfer it to the server, and still have a lot of gestures to just shove a piece of code on the server.





It would be nice to just pass the code to the server as a lambda, just as we pass a lambda to a function, also pass it to the server.





But I had an idea how to make this process easier, and I did something.





1 | var query = TcpQuery
2 |    .create(IEnv.class).host("myserver.com").port(9988)
3 |      .build();
4 |
5 |  query.apply( 
6 |      env -> env.processes().stream().filter(
7 |          p -> p.getName().contains("java")
8 |      )
9 |      .collect(Collectors.toList())
10|  ).forEach(System.out::println);
      
      



Here is the java code,





  • Lines 1 through 5 inclusive and 10 - work on the client





  • 6 9 ( env->...)





, Java (11).





6 9 ( ) , , , - deploy, IDE (Idea/Eclipse/etc...).





, Serializable Lambda Java, - , , .. deploy api ( ).






IEnv:





public interface IEnv {
	List<OsProc> processes();
}
      
      







public class OsProc implements Serializable {
	public Optional<Integer> getPpid(){ return ... }
	public int getPid(){ return ... }
	public void setPid(int pid){ ... }
	public String getName(){ return ... }
	public Optional<String> getCmdline(){ return ... }
}
      
      







var query = TcpQuery
   .create(IEnv.class).host("myserver.com").port(9988)
 	.build();
 
 query.apply(
 	env -> env.processes().stream().filter(
     	p -> p.getName().contains("java")
 	)
 	.collect(Collectors.toList())
 ).forEach(System.out::println);
      
      



- ?

Java





  1. , Client.java





  2. - - Client.class





  3. query.apply() - env -> env.proc...toList())





  4. query.apply():









    1. ( Client) ( lambda1)





    2. - (Client.class)





    3. -





      1. -





      2. -

















      1. //













  5. query.apply()





, -, IDE .





?

, pet project-:





v 1.0 https://github.com/gochaorg/trambda/releases/tag/1.0





maven





<dependency>
  <groupId>xyz.cofe</groupId>
  <artifactId>trambda</artifactId>
  <version>1.0</version>
  <type>pom</type>
</dependency>

<dependency>
  <groupId>xyz.cofe</groupId>
  <artifactId>trambda-core</artifactId>
  <version>1.0</version>
</dependency>

<dependency>
  <groupId>xyz.cofe</groupId>
  <artifactId>trambda-tcp</artifactId>
  <version>1.0</version>
</dependency>
      
      



, (TCP)





, :





  • OsProc.java - ( )





  • IEnv.java - ( )





  • LinuxEnv.java - Linux - IEnv





:





package xyz.cofe.trambda.demo.api;

import org.junit.jupiter.api.Test;

public class LinuxEnvTest {
   @Test
   public void test(){
       var env = new LinuxEnv();
       env.processes().stream()
           .filter(p->p.getName().equalsIgnoreCase("java"))
           .forEach(System.out::println);
   }
}
      
      



LinuxEnv - , :





package xyz.cofe.trambda.demo.api;

import java.util.ArrayList;
import java.util.List;
import xyz.cofe.io.fs.File;

public class LinuxEnv implements IEnv {
   @Override
   public List<OsProc> processes(){
       ArrayList<OsProc> procs = new ArrayList<>();
       File procDir = new File("/proc");
       procDir.dirList().stream()
           .filter( d -> d.getName().matches("\\d+") && d.isDir() )
           .map(OsProc::linuxProc)
           .forEach(procs::add);
       return procs;
   }
}
      
      



, /proc , ( Linux / /proc)





( …)





(git commit 67ec260)





> git clone https://github.com/gochaorg/trambda.git
  Β«trambdaΒ»...
remote: Enumerating objects: 978, done.
remote: Counting objects: 100% (978/978), done.
remote: Compressing objects: 100% (464/464), done.
remote: Total 978 (delta 308), reused 862 (delta 195), pack-reused 0
 : 100% (978/978), 715.70 KiB | 559.00 KiB/s, .
 : 100% (308/308), .
      
      







user@user-Modern-14-A10RB:22:10:35:~//sample-tr:
> cd trambda/trambda-demo/tr-demo-api/
user@user-Modern-14-A10RB:22:10:49:~//sample-tr/trambda/trambda-demo/tr-demo-api:
> mvn clean package install
...
[INFO] ------------------------------------------------------------------------
[INFO] BUILD SUCCESS
[INFO] ------------------------------------------------------------------------
[INFO] Total time:  13.933 s
[INFO] Finished at: 2021-04-18T22:11:11+05:00
[INFO] ------------------------------------------------------------------------
      
      



target jar





user@user-Modern-14-A10RB:22:13:13:~//sample-tr/trambda/trambda-demo/tr-demo-api:
> ll target/
 48
drwxrwxr-x 10 user user 4096  18 22:11 ./
drwxrwxr-x  4 user user 4096  18 22:11 ../
drwxrwxr-x  3 user user 4096  18 22:11 classes/
drwxrwxr-x  3 user user 4096  18 22:11 generated-sources/
drwxrwxr-x  3 user user 4096  18 22:11 generated-test-sources/
drwxrwxr-x  2 user user 4096  18 22:11 maven-archiver/
drwxrwxr-x  3 user user 4096  18 22:11 maven-status/
drwxrwxr-x  4 user user 4096  18 22:11 site/
drwxrwxr-x  2 user user 4096  18 22:11 surefire-reports/
drwxrwxr-x  3 user user 4096  18 22:11 test-classes/
-rw-rw-r--  1 user user 6337  18 22:11 tr-demo-api-1.0-SNAPSHOT.jar
      
      



github





user@user-Modern-14-A10RB:22:37:25:~//sample-tr:
> wget https://github.com/gochaorg/trambda/releases/download/1.0/trambda-tcp-serv-cli.zip
--2021-04-18 22:37:31--  https://github.com/gochaorg/trambda/releases/download/1.0/trambda-tcp-serv-cli.zip
 github.com (github.com)... 140.82.121.4
  github.com (github.com)|140.82.121.4|:443...  .
HTTP- .  ... 302 Found
: https://github-releases.githubusercontent.com/350075998/47380d00-9b40-11eb-90a4-4e353f42e67c?X-Amz-Algorithm=AWS4-HMAC-SHA256&X-Amz-Credential=AKIAIWNJYAX4CSVEH53A%2F20210418%2Fus-east-1%2Fs3%2Faws4_request&X-Amz-Date=20210418T173731Z&X-Amz-Expires=300&X-Amz-Signature=97ade1f58bfbe1eaa320805179987e8c4df730b9f5eddf24c05662fb676caafe&X-Amz-SignedHeaders=host&actor_id=0&key_id=0&repo_id=350075998&response-content-disposition=attachment%3B%20filename%3Dtrambda-tcp-serv-cli.zip&response-content-type=application%2Foctet-stream []
--2021-04-18 22:37:31--  https://github-releases.githubusercontent.com/350075998/47380d00-9b40-11eb-90a4-4e353f42e67c?X-Amz-Algorithm=AWS4-HMAC-SHA256&X-Amz-Credential=AKIAIWNJYAX4CSVEH53A%2F20210418%2Fus-east-1%2Fs3%2Faws4_request&X-Amz-Date=20210418T173731Z&X-Amz-Expires=300&X-Amz-Signature=97ade1f58bfbe1eaa320805179987e8c4df730b9f5eddf24c05662fb676caafe&X-Amz-SignedHeaders=host&actor_id=0&key_id=0&repo_id=350075998&response-content-disposition=attachment%3B%20filename%3Dtrambda-tcp-serv-cli.zip&response-content-type=application%2Foctet-stream
 github-releases.githubusercontent.com (github-releases.githubusercontent.com)... 185.199.111.154, 185.199.108.154, 185.199.109.154, ...
  github-releases.githubusercontent.com (github-releases.githubusercontent.com)|185.199.111.154|:443...  .
HTTP- .  ... 200 OK
: 12107487 (12M) [application/octet-stream]
 : Β«trambda-tcp-serv-cli.zipΒ»

trambda-tcp-serv-cli.zip                                    100%[========================================================================================================================================>]  11,55M  3,75MB/s     3,1s    

2021-04-18 22:37:35 (3,75 MB/s) - Β«trambda-tcp-serv-cli.zipΒ»  [12107487/12107487]

user@user-Modern-14-A10RB:22:37:35:~//sample-tr:
> ll
 11836
drwxrwxr-x  3 user user     4096  18 22:37 ./
drwxr-xr-x 11 user user     4096  18 22:00 ../
drwxrwxr-x 10 user user     4096  18 22:10 trambda/
-rw-rw-r--  1 user user 12107487  12 03:36 trambda-tcp-serv-cli.zip
user@user-Modern-14-A10RB:22:37:42:~//sample-tr:
> unzip trambda-tcp-serv-cli.zip 
Archive:  trambda-tcp-serv-cli.zip
   creating: trambda-tcp-serv-cli/
   creating: trambda-tcp-serv-cli/jars/
  inflating: trambda-tcp-serv-cli/jars/asm-9.1.jar  
  inflating: trambda-tcp-serv-cli/jars/jline-2.14.6.jar  
  inflating: trambda-tcp-serv-cli/jars/iofun-1.0.jar  
  inflating: trambda-tcp-serv-cli/jars/groovy-swing-3.0.7.jar  
  inflating: trambda-tcp-serv-cli/jars/groovy-console-3.0.7.jar  
  inflating: trambda-tcp-serv-cli/jars/groovy-xml-3.0.7.jar  
  inflating: trambda-tcp-serv-cli/jars/trambda-tcp-serv-cli-1.0.jar  
  inflating: trambda-tcp-serv-cli/jars/ecolls-1.10.jar  
  inflating: trambda-tcp-serv-cli/jars/trambda-core-1.0.jar  
  inflating: trambda-tcp-serv-cli/jars/slf4j-api-1.7.25.jar  
  inflating: trambda-tcp-serv-cli/jars/asm-tree-9.1.jar  
  inflating: trambda-tcp-serv-cli/jars/asm-util-9.1.jar  
  inflating: trambda-tcp-serv-cli/jars/fs-1.2.jar  
  inflating: trambda-tcp-serv-cli/jars/logback-classic-1.2.3.jar  
  inflating: trambda-tcp-serv-cli/jars/trambda-tcp-1.0.jar  
  inflating: trambda-tcp-serv-cli/jars/groovy-groovysh-3.0.7.jar  
  inflating: trambda-tcp-serv-cli/jars/groovy-templates-3.0.7.jar  
  inflating: trambda-tcp-serv-cli/jars/asm-analysis-9.1.jar  
  inflating: trambda-tcp-serv-cli/jars/text-1.0.jar  
  inflating: trambda-tcp-serv-cli/jars/logback-core-1.2.3.jar  
  inflating: trambda-tcp-serv-cli/jars/groovy-3.0.7.jar  
  inflating: trambda-tcp-serv-cli/jars/cbuffer-1.3.jar  
   creating: trambda-tcp-serv-cli/bin/
  inflating: trambda-tcp-serv-cli/bin/trambda-tcp-serv.bat  
  inflating: trambda-tcp-serv-cli/bin/trambda-tcp-serv  
user@user-Modern-14-A10RB:22:37:50:~//sample-tr:
> rm trambda-tcp-serv-cli.zip 
      
      



trambda-tcp-serv-cli/jars





ser@user-Modern-14-A10RB:22:40:47:~//sample-tr:
> cp -v trambda/trambda-demo/tr-demo-api/target/tr-demo-api-1.0-SNAPSHOT.jar trambda-tcp-serv-cli/jars/
'trambda/trambda-demo/tr-demo-api/target/tr-demo-api-1.0-SNAPSHOT.jar' -> 'trambda-tcp-serv-cli/jars/tr-demo-api-1.0-SNAPSHOT.jar'
      
      



, groovy ( , , Java)





:





> cat trambda/trambda-tcp-serv-cli/src/test/samples/sample-1.groov
      
      



//  xyz.cofe.trambda.demo.api.LinuxEnv 
//     9988,      IP
app.service( "0.0.0.0:9988", new xyz.cofe.trambda.demo.api.LinuxEnv() ) {
    daemon false
    //   
    security {
        //  API/   
        allow {
            // method("System") {
            //     methodOwner ==~ /java.lang.System/ && methodName in ['gc']
            // }
            // field( "System.out" ) {
            //     fieldOwner ==~ /java.lang.System/ && fieldName in ['out','in','err'] && readAccess
            // }
            invoke( 'Java compiler' ){
                methodOwner ==~ /java\.lang\.invoke\.(LambdaMetafactory|StringConcatFactory)/
            }
            invoke( 'Java collections' ){
                methodOwner ==~ /java\.util\.(stream\.(Stream|Collectors)|(List))/
            }
            invoke( 'Java lang' ){
                methodOwner ==~ /java\.lang\.String/
            }
            invoke( 'Api '){
                methodOwner ==~ /xyz\.cofe\.trambda\.demo\.api\.(IEnv|OsProc)/
            }
        }
        //     -  
        deny {
            any("ban all")
        }
    }
}
      
      







user@user-Modern-14-A10RB:22:56:08:~//sample-tr:
> bash ./trambda-tcp-serv-cli/bin/trambda-tcp-serv -s trambda/trambda-tcp-serv-cli/src/test/samples/sample-1.groovy
# [main] INFO  x.c.t.tcp.serv.cli.TcpServerCLI - starting xyz.cofe.trambda.tcp.serv.cli.TcpServerCLI 
# [main] INFO  x.c.t.tcp.serv.cli.TcpServerCLI - executeScript( "trambda/trambda-tcp-serv-cli/src/test/samples/sample-1.groovy", UTF-8 ) 
# [main] INFO  x.c.t.tcp.serv.cli.TcpServerCLI - registry class xyz.cofe.trambda.demo.api.LinuxEnv on 0.0.0.0:9988 
# [main] INFO  x.c.t.tcp.serv.cli.TcpServerCLI - starting service xyz.cofe.trambda.demo.api.LinuxEnv@55e7a35c on /0.0.0.0:9988 
# [main] DEBUG x.c.t.tcp.serv.cli.TcpServerCLI - create server socket 
# [main] DEBUG x.c.t.tcp.serv.cli.TcpServerCLI - bind server socket /0.0.0.0:9988 
# [main] DEBUG x.c.t.tcp.serv.cli.TcpServerCLI - server started 
      
      



, ,





(ClientTest.java)





package xyz.cofe.trambda.demo.client;

import java.util.stream.Collectors;
import org.junit.jupiter.api.Test;
import xyz.cofe.trambda.demo.api.IEnv;
import xyz.cofe.trambda.tcp.TcpQuery;

public class ClientTest {
   @Test
   public void test01(){
       var query = TcpQuery
           .create(IEnv.class).host("localhost").port(9988)
           .build();

       query.apply(
           env -> env.processes().stream().filter(p ->
               p.getName().contains("java"))
           .collect(Collectors.toList())
       ).forEach(System.out::println);
   }
}
      
      



, , - ..





?

- ..





, :





//  TCP 
ServerSocket ssocket = new ServerSocket(port);

//  
ssocket.setSoTimeout(1000*5);

//  
server = new TcpServer<IEnv>(
    //  
    ssocket,
    
    //       
    s -> new LinuxEnv(),
    
    //  
    SecurityFilters.create(s -> {
        
        //    -   
        s.allow( a -> {
            
            //  API   
            a.invoke("demo api", c->
                c.getOwner().matches(
                    "xyz\\.cofe\\.trambda\\.tcp\\.demo\\.([\\w\\d]+)"));
            
            //   
            a.invoke("java collections api", c->c.getOwner().matches(
                "java\\.util\\.(List)|java\\.util\\.stream\\.([\\w\\d]+)"));
            
            //   Java 
            a.invoke("java lang api", c->
                c.getOwner().matches("java\\.lang\\.(String)"));
            
            //     Java
            a.invoke("java compiler", c->
                c.getOwner().matches(
                    "java\\.lang\\.invoke\\.(LambdaMetafactory|StringConcatFactory)"));
        });
        
        //   
        s.deny().any("by default");
    })
);

//   Thread     
server.setDaemon(true);

//  
server.start();//  TCP 
ServerSocket ssocket = new ServerSocket(port);

//  
ssocket.setSoTimeout(1000*5);
      
      



,









  • ,





  • ,





  • Java  





    • LambdaMetafactory





    • StringConcatFactory +





  • / - . SecurityFilters.java /  PredicateBuilder#field





  • , Object.toString() ,





, github git pages





?

, , RMI, gRPC ?





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    • / /

















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      • //…





















      • ..









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Java-RMI





SOAP





REST-JSON





SQL





GraphQL





Hadoop









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  • (Java-RMI, SOAP, REST-JSON, GraphQL)





    • (Java-RMI, SOAP, GraphQL)





    • (REST-JSON, Hadoop)





  • - (SQL, Hadoop)





SQL





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  • (*)





    • / /













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    • … (**)













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- AST/Java/…, JAD





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?

, Java , - .class, java , : obj.getClass()





Class , Class.getResource(β€˜ ’) URL .





β€œ , ”





, …





, ?





package xyz.cofe.trambda.l1;

import java.util.function.Function;
import org.junit.jupiter.api.Test;

public class SimpleLambdaTest {
   @Test
   public void javaLambda01(){
       Function<Function<String,String>,String> test = (f) -> {
           System.out.println("f="+f.getClass());
           return null;
       };
       test.apply( x -> x.repeat(4) );
   }
}
      
      



:





f=class xyz.cofe.trambda.l1.SimpleLambdaTest$$Lambda$235/0x0000000800142040





test-classes/ SimpleLambdaTest$$Lambda$235,





user@user-Modern-14-A10RB:00:41:32:~/code/trambda/trambda-core/target/test-classes/xyz/cofe/trambda/l1:
> ll
 12
drwxrwxr-x 2 user user 4096  25 00:40 ./
drwxrwxr-x 5 user user 4096  25 00:40 ../
-rw-rw-r-- 1 user user 2162  25 00:40 SimpleLambdaTest.class
      
      







> javap -p SimpleLambdaTest.class 
Compiled from "SimpleLambdaTest.java"
public class xyz.cofe.trambda.l1.SimpleLambdaTest {
  public xyz.cofe.trambda.l1.SimpleLambdaTest();
  public void javaLambda01();
  private static java.lang.String lambda$javaLambda01$1(java.lang.String);
  private static java.lang.String lambda$javaLambda01$0(java.util.function.Function);
}

      
      



- lambda$javaLambda01$1 lambda$javaLambda01$0 , ,





class Java , .





Java Serializable,









package xyz.cofe.trambda.l2;

import java.io.Serializable;
import java.util.function.Function;

public interface Fn<A,Z> extends Function<A,Z> , Serializable {
}
      
      







Runnable r = (Runnable & Serializable)() -> System.out.println("Serializable!");
      
      



Java ,





package xyz.cofe.trambda.l2;

import java.lang.invoke.SerializedLambda;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.util.function.Function;
import org.junit.jupiter.api.Test;

public class SerialLambdaTest {
   @Test
   public void serLambda01(){
       Fn<Fn<String,String>,String> test = (lambda) -> {
           System.out.println("lambda="+lambda.getClass());

           Method writeReplace = null;
           try{
               writeReplace = lambda.getClass().getDeclaredMethod("writeReplace");
               writeReplace.setAccessible(true);

               SerializedLambda sl = (SerializedLambda) writeReplace.invoke(lambda);
               System.out.println(sl);
           } catch( NoSuchMethodException | InvocationTargetException | IllegalAccessException e ) {
               e.printStackTrace();
           }

           return null;
       };
       test.apply( x -> x.repeat(4) );
   }
}
      
      



, .





lambda=class xyz.cofe.trambda.l2.SerialLambdaTest$$Lambda$235/0x0000000800142040
SerializedLambda[capturingClass=class xyz.cofe.trambda.l2.SerialLambdaTest, 
functionalInterfaceMethod=xyz/cofe/trambda/l2/Fn.apply:(Ljava/lang/Object;)
Ljava/lang/Object;, 
implementation=invokeStatic 
xyz/cofe/trambda/l2/SerialLambdaTest.lambda$serLambda01$3fed5817$1:
(Ljava/lang/String;)Ljava/lang/String;, 
instantiatedMethodType=(Ljava/lang/String;)Ljava/lang/String;, numCaptured=0]

      
      







user@user-Modern-14-A10RB:00:51:48:~/code/trambda/trambda-core/target/test-classes/xyz/cofe/trambda/l2:
> javap -p SerialLambdaTest.class 
Compiled from "SerialLambdaTest.java"
public class xyz.cofe.trambda.l2.SerialLambdaTest {
  public xyz.cofe.trambda.l2.SerialLambdaTest();
  public void serLambda01();
  private static java.lang.Object $deserializeLambda$(java.lang.invoke.SerializedLambda);
  private static java.lang.String lambda$serLambda01$3fed5817$1(java.lang.String);
  private static java.lang.String lambda$serLambda01$47b6c34$1(xyz.cofe.trambda.l2.Fn);
}

      
      



- $deserializeLambda$ , Serializable .





java.lang.invoke.SerializedLambda - final , ,





  • String getImplClass() - , .





  • String getImplMethodName() - .





stdout





implementation=invokeStatic xyz/cofe/trambda/l2/SerialLambdaTest.lambda$serLambda01$3fed5817$1:(Ljava/lang/String;)Ljava/lang/String;





:





private static java.lang.String lambda$serLambda01$3fed5817$1(java.lang.String);





.. -





, - , :





SerializedLambda sl = (SerializedLambda)writeReplace.invoke(lambda);
var implClassName = sl.getImplClass()

var implClassUrl =
labmda.getClass().getResource("/"+implClassName.replace(".","/")+".class");
      
      



implClassUrl -





URL





byte[] classByteCode = null;
try{
   classByteCode = IOFun.readBytes(implClassUrl);
} catch( IOException e ) {
   throw new IOError(e);
}
      
      



ASM





var classReader = new ClassReader(classByteCode);
      
      







ClassVisitor cv = new ClassVisitor(Opcodes.ASM9) {
   @Override
   public MethodVisitor visitMethod(int access, String name, String descriptor, String signature, String[] exceptions) {
       if( methName.equals(name) && descriptor!=null && descriptor.equals(methSign) ){
           mdef0.set(new MethodDef(access,name,descriptor,signature,exceptions));
           return dump(byteCodes::add);
       }
       return null;
   }
};

cr.accept(cv, 0);
      
      



MethodVisior



- . , MethodDump extends MethodVisitor



:





package xyz.cofe.trambda;
public class MethodDump extends MethodVisitor implements Opcodes {
...

@Override
public void visitParameter(String name, int access){
   emit(new MParameter(name,access));
}

@Override
public void visitInsn(int opcode){
   emit(new MInsn(opcode));
}

...
}
      
      



visitXXXX(...) - ( )





, visitInsn( op ) new MInsn(op), emit(..)





, ( )





xyz.cofe.trambda.MethodRestore





public synchronized byte[] generate(){
  //    
  binClassName = className.replace('.', '/');

//  ClassWriter ( ASM) 
//      visitXXXX( op )
var cw = new ClassWriter(ClassWriter.COMPUTE_MAXS|ClassWriter.COMPUTE_FRAMES);
cw.visit(Opcodes.V11,
   Opcodes.ACC_PUBLIC|Opcodes.ACC_SUPER,
   binClassName,null,
   "java/lang/Object", null
);

//  
var mv = cw.visitMethod(
  acc, //   static public
  name, //  
  desc, //  
  sign, //    Generic 
  excepts); //     

//        
//    visitXXXX()
//      ,    
for( var bc : byteCodes ){
   if( bc instanceof MCode )build((MCode) bc);
   else if( bc instanceof MEnd )build((MEnd) bc);
   else if( bc instanceof MLabel )build((MLabel) bc);
   else if( bc instanceof MLineNumber )build((MLineNumber) bc);
   else if( bc instanceof MVarInsn )build((MVarInsn) bc);
  ...
}

//   
return cw.toByteArray();
}


//  visitCode() -  
protected void build(MCode code){ mv.visitCode(); }
//  visitEnd() -  
protected void build(MEnd end){ mv.visitEnd(); }
protected void build(MTypeInsn tinst){
   mv.visitTypeInsn(tinst.getOpcode(), tinst.getOperand());
}
      
      



,





ClassLoader







var byteCode = new MethodRestore()
   .className(clName)
   .methodName("lambda1")
   .methodDef(mdef)
   .generate();

ClassLoader cl = new ClassLoader(ClassLoader.getSystemClassLoader()) {
   @Override
   protected Class<?> findClass(String name) throws ClassNotFoundException{
       if( name!=null && name.equals(clName) ){
           return defineClass(name,byteCode,0,byteCode.length);
       }
       return super.findClass(name);
   }
};
      
      







System.out.println("try read class "+clName);
Class c = null;
try{
   c = Class.forName(clName,true,cl);
   System.out.println("class found "+c);
} catch( ClassNotFoundException e ) {
   e.printStackTrace();
   return;
}
      
      







Method m = null;
System.out.println("methods");
for( var delMeth : c.getDeclaredMethods() ){
  System.out.println(""+delMeth);
  if( delMeth.getName().equals(methName) ){
    m = delMeth;
  }
}
      
      







try{
   Object arg0 = "abc";
   System.out.println("call with "+arg0);
   Object res = m.invoke(null, arg0);
   System.out.println("result "+res);
} catch( IllegalAccessException | InvocationTargetException e ) {
   e.printStackTrace();
}
      
      











    1. Kotlin , .. Kotlin , Scala





    2. (Groovy, JavaScript) - , AST - , .





  1. - - ,





  2. Potentially on the client, Java may be newer, with a different bytecode than on the server, the server may not know about any constructs of the new Java





  3. The library does not transfer all the byte code, this is due to the fact that not all byte code has an object representation - perhaps this is a question to be solved, a question of refinement.





  4. Separately - it's a matter of network transmission





    1. Security issue - technically it can be solved, but it requires finishing with a file





    2. The transfer protocol, my library uses TCP, but this network layer can always be changed to a more suitable one for you, but of course it will require its implementation, in fact, the serialization of the lambda and its restoration in no way limit the network layer.








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