ctxsh

A demonstration app which illustrates how to expose a Spring ApplicationContext to Groovy as an executable shell

Requires

• Maven
• Java 8

The application here uses Spring Data JPA, but that's more of a party trick than anything else. My motivation in doing this is more because I have a lot of operations to perform that are MUCH easier to do if I have direct access to the Service tier of my application (without having to write a UI). For example, I occasionally have to fetch arbitrary datasets via web services, run business rules, trigger scheduled tasks, manage queues, and manage users.

All of the data here is stored in an embedded H2 database. Any JDBC configuration should be fine. I'm using Spring @Transaction support and a TransactionTemplate.

Many of the above tasks are well suited to a Groovy DSL.

Running

mvn clean install
mvn exec:java

If you're serious about using this, you can modify ctxsh to point to the compiled "-with-dependencies.jar" file. And place ctxsh on your $PATH. From there you'll be able to run it like any other shell (except it's not a shell - it's not interpreting things one line at a time, it's really expecting file input until EOF).

$ ctxsh
2017-11-11 19:54:32 INFO  Shell:27 - Using groovy
2017-11-11 19:54:32 INFO  AnnotationConfigApplicationContext:589 - Refreshing org.springframework.context.annotation.AnnotationConfigApplicationContext@4141d797: startup date [Sat Nov 11 19:54:32 CST 2017]; root of context hierarchy
2017-11-11 19:54:32 INFO  AutowiredAnnotationBeanPostProcessor:154 - JSR-330 'javax.inject.Inject' annotation found and supported for autowiring
2017-11-11 19:54:32 INFO  PostProcessorRegistrationDelegate$BeanPostProcessorChecker:326 - Bean 'myConfig' of type [be.shouldyou.example.MyConfig$$EnhancerBySpringCGLIB$$7b5ad687] is not eligible for getting processed by all BeanPostProcessors (for example: not eligible for auto-proxying)
......
2017-11-11 19:54:32 INFO  EmbeddedDatabaseFactory:189 - Starting embedded database: url='jdbc:h2:mem:testdb;DB_CLOSE_DELAY=-1;DB_CLOSE_ON_EXIT=false', username='sa'
2017-11-11 19:54:33 INFO  LocalContainerEntityManagerFactoryBean:354 - Building JPA container EntityManagerFactory for persistence unit 'default'
2017-11-11 19:54:35 INFO  Shell:37 - Bound org.springframework.orm.jpa.SharedEntityManagerCreator#0 to Shared EntityManager proxy for target factory [org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean@6ddd71cc]
2017-11-11 19:54:35 INFO  Shell:51 - txStatus variable bound

Note that you'll need to send an EOF (ctrl-d) to exit the "shell."

A script would look like this:

#!/usr/bin/env ctxsh
println "Hello World!"
Submission s = new Submission();
em.persist(s);
commit=true

Transactions

All work happens within the scope of a single transaction, which will be rolled back unless commit=true is specified somewhere within the script.

You also have access to a Spring TransactionStatus variable txStatus. This example goes through and exposes every Spring Bean as a variable to the script. For convenience, an EntityManager is included as em.

To make scripts more concise, you may add any imports you need to import.sh. In this example, the application's (JPA) entity classes are imported.

JSR 223

The examples here use Groovy. They just as easily could have been any other language with JSR223 support. Using the ECMAScript implementation included with the JDK works quite well, but I was unable to find a decent "import" mechanism.

Wishlist Items

• Make this interpret as a shell, one line at a time.
• Make this a REPL.
• Do it in Javascript.
• Do this from a web app.