06_Services

Services example

Services allow for loose coupling between service consumers modules and service providers modules.

This example has a service consumer module and a service provider module:

• module com.socket exports an API for network sockets. The API is in package com.socket so this package is exported. The API is plug-able to allow for alternative implementations. The service type is class com.socket.spi.NetworkSocketProvider in the same module and thus package com.socket.spi is also exported.

• module org.fastsocket is a service provider module. It provides an implementation of com.socket.spi.NetworkSocketProvider. It does not export any packages.

Perform the below commands to see the contents of the respective sources contained in the src folder:

• module com.socket

  $ cat src/com.socket/module-info.java
  $ cat src/com.socket/com/socket/NetworkSocket.java
  $ cat src/com.socket/com/socket/spi/NetworkSocketProvider.java
  

• module org.fastsocket

  $ cat src/org.fastsocket/module-info.java
  $ cat src/org.fastsocket/org/fastsocket/FastNetworkSocketProvider.java
  $ cat src/org.fastsocket/org/fastsocket/FastNetworkSocket.java
  

• module com.greetings

  $ cat src/com.greetings/module-info.java
  $ cat src/com.greetings/com/greetings/Main.java
  

Note: in case one of the below .sh script fails due to the tree command, please take a look at Download and install the tree and wget command section in the README.md file and apply the appropriate solution.

Both the modules are compiled together from the sources into the folder mods with the following commands:

$ ./compile.sh

And we run the example with the following command:

$ ./run.sh

Check the contents of both these script files (use the cat command or a text editor) to see what they are doing and why - interesting instructions and information in there.

See ../01_Greetings/README.md to learn more about package and module naming conventions and how to avoid confusions between them.