Simple Java/Scala Configuration Injection with Guice

Problem and Audience

One of the things every microservice needs is a mechanism for injecting configuration, so we developed a little json configuration helper for our littleware scala code that overlays a hierarchy of json configuration objects, and integrates with our module runtime and dependency-injection framework.

Configuration in Littleware

Littleware has a simple ServiceLoader based module runtime system that integrates with a guice dependency injection container. In practice what that means is that each java or scala jar includes a Module class that implements a simple callback interface for defining configuration injection bindings, and registering application event listeners (startup and shutdown). We have now augmented this platform with a json configuration helper that allows a module developer to provide configuration defaults on the classpath in the jar file, and the stack operator to override those defaults with a json file on an environment-defined search path or with json in an environment variable.

Here's how it works. The JsonConfigLoader provides a loadConfig helper that takes a key as an argument and returns a JsonObject (we use the gson json library).

The JsonConfigLoader also provides a bindKeys method that consumes a json object and a guice binder, converts the json to a list of (key, value) pairs, maps the values back to strings, and binds each key to its string value using guice's @Named binding facility.

So in the Module.scala (or .java) file described above, the module bootstrap code does something like this:

littleware.scala.JsonConfigLoader.loadConfig(CONFIG_KEY).map(
  {
    jsConfig =>
    littleware.scala.JsonConfigLoader.bindKeys(binder, jsConfig)
  }
)

Finally, a configuration provider can consume the bound configuration strings - like this:

@inject.Singleton()
    class ConfigProvider @inject.Inject() (
        @inject.name.Named("little.cloudmgr.sessionmgr.awsconfig") configStr:String,
        gs: gson.Gson
    ) extends inject.Provider[Config] {
        lazy val singleton: Config = {
            val js = gs.fromJson(configStr, classOf[gson.JsonObject])
            Config(
              js.getAsJsonPrimitive("oidcJwksUrl").getAsString(),
              Option(js.getAsJsonPrimitive("kmsSigningKey")).map({ _.getAsString() }),
              js.getAsJsonArray("kmsPublicKeys").asScala.map({ jsIt => jsIt.getAsJsonPrimitive().getAsString() }).toSet
            )
        }

        override def get():Config = singleton
    }

In the cloudmgr module above the configuration key is LITTLE_CLOUDMGR, so the config loader first loads littleware/config/LITTLE_CLOUDMGR.json off the classpath - which provides some developer defaults. The loader then searches the folders from the LITTLE_CONFIG_PATH environment (or system) variable until it finds a LITTLE_CLOUDMGR.json file, and it loads that, and does a shallow json merge. Finally, the config loader looks for a LITTLE_CLOUDMGR system (or environment) variable, and again merges the keys.

What does our configuration look like? We want to avoid collisions between binding keys from different modules, so the keys in a config json follow the java package reverse-dns pattern. Also, I like to have simple patterns that I can follow, so each service implementation in the module that requires configuration defines its own Config class and Provider[Config] that consumes a particular configuration key (that can be individually overriden via the configuration merge process described above). For example, the cloudmgr module has two service implementation, LocalKeySessionMgr and AwsSessionMgr, and the json configuration for the module looks like this:

{
    "little.cloudmgr.domain" : "test-cloud.frickjack.com",
    "little.cloudmgr.sessionmgr.type": "local",
    "little.cloudmgr.sessionmgr.localconfig": {
        "signingKey": { "kid": "testkey", "pem": "-----BEGIN PRIVATE KEY-----\nMIGHAgEAMBMGByqGSM49AgEGCCqGSM49AwEHBG0wawIBAQQgs02I2exqJsdAoHef\n54/cjmlRvww903MKp0AOPqlRRXqhRANCAATWdeIowEmJ5lxpm7gE8GtvBnB1FBTI\nlcZHdD1FPM90oeEAraGGtnluYYEdPiJP3r29n3qFcGTgvqDAE49bc4om\n-----END PRIVATE KEY-----" }, 
        "verifyKeys": [ 
            { "kid": "testkey", "pem": "-----BEGIN PUBLIC KEY-----\nMFkwEwYHKoZIzj0CAQYIKoZIzj0DAQcDQgAE1nXiKMBJieZcaZu4BPBrbwZwdRQU\nyJXGR3Q9RTzPdKHhAK2hhrZ5bmGBHT4iT969vZ96hXBk4L6gwBOPW3OKJg==\n-----END PUBLIC KEY-----" } 
        ],
        "oidcJwksUrl": "https://www.googleapis.com/oauth2/v3/certs" 
    }, 
    "little.cloudmgr.sessionmgr.awsconfig": {
        "kmsPublicKeys": [ 
            "alias/littleware/api/api-frickjack-com/sessMgrSigningKey", 
            "alias/littleware/api/api-frickjack-com/sessMgrOldKey" 
        ], 
        "kmsSigningKey": "alias/littleware/api/api-frickjack-com/sessMgrSigningKey", 
        "oidcJwksUrl": "https://cognito-idp.us-east-2.amazonaws.com/us-east-2_860PcgyKN/.well-known/jwks.json"
    },
    "little.cloudmgr.sessionmgr.lambdaconfig": {
        "corsDomainWhiteList": [ ".frickjack.com" ],
        "cookieDomain": ".frickjack.com"
    }
}

Summary

We developed a little json configuration helper for our littleware scala code that overlays a hierarchy of json configuration objects, and integrates with our module runtime and dependency-injection framework.

Bumping up to jdk8 and JEE 7

I bumped up littleware's build to pull in JEE7 jars, and also went ahead and setup a jdk8 pre-release runtime, and so far everything works great.

I discovered a while ago when I bumped up to JEE6 that the Java EE dependencies are a little weird. The published JEE jar files are just intended for use at compile time, and only include the EE API definitions - no implementation. The idea is that a user builds his code against the API jars, and deploys to a JEE container that implements the APIs. If a developer instead deploys to an embedded environment like jetty or my fishRunner or just a standalone app that does something like using hybernate for JPA, then it's up to the developer to pull in the necessary implementation jars at runtime.

CDI and Guice with jsr-300 javax.inject In Same Webapp

Things can get weird when java SE code developed with IOC is deployed into a java EE container that implements CDI. For example - the littleware code I work with implements simple modules and life cycle management with guice, so when I deploy that code in a webapp to a glassfish server I want guice's runtime to manage littleware's dependency injection, but I might also want CDI to inject a glassfish-managed JPA EntityManager into a servlet for me, and both guice and CDI are scanning for the same javax.inject runtime annotations. Fortunately - this kind of thing worked fine for me until recently, since CDI 1 as introduced in java EE 6 ignored jars that did not include a META-INF/beans.xml file.

Java Enterprise Edition 6 introduced JSR-330 (javax.inject annotations and provider interfaces) and JSR-299 (CDI - contexts and dependency injection) to the java-ee platform. The javax.inject package standardized the annotations and interfaces used by java's various inversion of control and dependency-injection systems (guice, spring, dagger, pico container, ...), so that code written with one IOC system in mind could be more easily used in an application that deployed to another system.

CDI introduced an IOC implementation for java enterprise edition (EE) technologies (servlets, JSF, EJB, JPA, ...) deployed in EE containers like glassfish, jboss, weblogic, and websphere.

I discovered CDI's behavior changed slightly in the new java EE 7 runtime when a webapp that ran fine in glassfish version 3 (a java EE 6 container) failed to deploy under glassfish 4 (the EE-7 reference implementation). The errors in the glassfish-4 logs lead me to this ticket in guava's bug database. It turns out that CDI's new version 1.1 runtime automatically scans all jars deployed with an enterprise application, and guava-14+ includes a couple classes with javax.inject annotations that CDI processed in an unintended way (littleware still uses guice's com.google.inject package annotations and interfaces, so CDI ignored those).

I eventually found one easy solution to this javax.inject - CDI 1.1 mix-up is to add a META-INF/beans.xml CDI config file to jars that include javax.inject annotations that require special or no handling by CDI. I added the following META-INF/beans.xml with a bean-discover-mode attribute set to "none" to the guava jar in my webapp, and that solved the problem. Hopefully guava's maintainers will add a similar beans.xml file to guava's binary distribution on maven central.

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://xmlns.jcp.org/xml/ns/javaee"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/beans_1_1.xsd"
       bean-discovery-mode="none">
</beans>

javase Hibernate: goodbye Ejb3Configuration, hello JNDI Context mock

I've been cleaning up littleware's asset database code this week, and was dismayed to discover upon updating the hibernate dependencies that the latest hibernate releases have deprecated and removed the Ejb3Configuration mechanism for bootstrapping a JPA environment and allocating an EntityManagerFactory in a javase (no javaee container) application. Fortunately - I came up with a hacky way to trick hibernate into using the DataSource instance I want it to use.

Somehow when I started working with JPA I already had code in littleware's guice-based IOC setup to initialize and inject DataSource instances in traditional JDBC code either directly or via JNDI lookup. When I started using JPA in littleware I wanted to wire things up so that JPA used the same DataSource as the rest of the code. When running in a web container like Tomcat or Glassfish the app can let the container manage the DataSource, and both JPA and the guice-runtime access the same DataSource via a directory (JNDI) lookup, but when running a standalone application, I had things coded up to use hibernate, and used Ejb3Configuration to tell hibernate to use littleware's DataSource.

Anyway, with Ejb3Configuration going away I had to specify the database connection parameters in a JPA persistence.xml file in one of two ways. The first option was to specify properties for a JDBC Driver that JPA (hibernate) would wrap with its own connection pool manager, and the first hack I tried implemented a JDBC Driver (it's just a one method interface) that pulled connections from littleware's DataSource. That actually worked fine - I'm always amazed when these things work. I setup persistence.xml like this:

<?xml version="1.0" encoding="UTF-8"?>

<persistence xmlns="http://java.sun.com/xml/ns/persistence"
             xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
             xsi:schemaLocation="http://java.sun.com/xml/ns/persistence http://java.sun.com/xml/ns/persistence/persistence_2_0.xsd"
             version="2.0">

  <persistence-unit name="littlewarePU" transaction-type="RESOURCE_LOCAL">
        <description>This JPA persistence unit tracks littleware assets
        </description>

        <!-- jndi datasource lookup        
        <non-jta-data-source>jdbc/littleDB</non-jta-data-source>
        -->
        
        <class>littleware.asset.server.db.jpa.AssetTypeEntity</class>
        <class>littleware.asset.server.db.jpa.TransactionEntity</class>
        <class>littleware.asset.server.db.jpa.AssetAttribute</class>
        <class>littleware.asset.server.db.jpa.AssetDate</class>
        <class>littleware.asset.server.db.jpa.AssetLink</class>
        <class>littleware.asset.server.db.jpa.AssetEntity</class>

    <properties>

      <property name="eclipselink.target-database" value="DERBY"/>
      <property name="eclipselink.ddl-generation" value="create-tables" />
      <property name="hibernate.hbm2ddl.auto" value="create"/>
      <property name="hibernate.dialect" value="org.hibernate.dialect.DerbyDialect" />
            
      <property name="javax.persistence.jdbc.driver" value="littleware.asset.server.db.jpa.LittleDriver"/>
      <property name="javax.persistence.jdbc.url" value="jdbc:littleware://ignore/this/stuff"/>
      <property name="javax.persistence.jdbc.user" value="APP"/>
      <property name="javax.persistence.jdbc.password" value="APP"/>

    </properties> 
    
  </persistence-unit>
</persistence>

And I wrote a bogus littleware.asset.server.db.jpa.LittleDriver that some initialization code configured via its setDataSource() method:

/**
 * JDBC driver that just delegates to the active DataSource defined in the
 * active littleware runtime.
 * Register this driver with JPA persistence.xml to plug into the
 * littleware managed DataSource.
 */
public class LittleDriver implements Driver {
    private static  DataSource dataSource = null;
    /**
     * HibernateProvider injects littleware data source at startup time as needed
     */
    public static void setDataSource( DataSource value ) {
        dataSource = value;
    }
    
    
    @Override
    public Connection connect(String string, Properties prprts) throws SQLException {
        Whatever.get().check( "LittleDriver requires data source injection",  null != dataSource );
        return dataSource.getConnection();
    }

    @Override
    public boolean acceptsURL(String string) throws SQLException {
        return true;
    }

    private static final DriverPropertyInfo[] empty = new DriverPropertyInfo[0];
    @Override
    public DriverPropertyInfo[] getPropertyInfo(String string, Properties prprts) throws SQLException {
        return empty;
    }

    @Override
    public int getMajorVersion() {
        return 0;
    }

    @Override
    public int getMinorVersion() {
        return 0;
    }

    @Override
    public boolean jdbcCompliant() {
        return false;
    }

    private static final Logger log = Logger.getLogger( LittleDriver.class.getName() );
    @Override
    public Logger getParentLogger() throws SQLFeatureNotSupportedException {
        return log;
    }
    
}

Anyway - that worked great, and it's actually good enough for my current needs (mostly just junit tests), but it made me itch thinking about hibernate wrapping a connection pool around a mock driver that pulls connections from another connection pool. Ugh. So I started thinking about setting up an in-memory JNDI directory where initialization code could stuff the DataSource before allocating the JPA (hibernate or whatever) EntityManagerFactory. I found this cool little SimpleJNDI JNDI implementation, but it wasn't registered with Maven central, and it was a little bigger than I would like to copy into my code base, and anyway - I didn't need a whole JNDI implementation - I just needed to trick hibernate into using my DataSource, so I tried just wiring up a mock JNDI Context, and it worked! It took a few tries to figure out which methods hibernate calls to do its directory lookup, but in the end I wound up with a persistence.xml file like this:

<?xml version="1.0" encoding="UTF-8"?>

<persistence xmlns="http://java.sun.com/xml/ns/persistence"
             xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
             xsi:schemaLocation="http://java.sun.com/xml/ns/persistence http://java.sun.com/xml/ns/persistence/persistence_2_0.xsd"
             version="2.0">

  <persistence-unit name="littlewarePU" transaction-type="RESOURCE_LOCAL">
        <description>This JPA persistence unit tracks littleware assets
        </description>

        <non-jta-data-source>jdbc/littleDB</non-jta-data-source>
        
        <class>littleware.asset.server.db.jpa.AssetTypeEntity</class>
        <class>littleware.asset.server.db.jpa.TransactionEntity</class>
        <class>littleware.asset.server.db.jpa.AssetAttribute</class>
        <class>littleware.asset.server.db.jpa.AssetDate</class>
        <class>littleware.asset.server.db.jpa.AssetLink</class>
        <class>littleware.asset.server.db.jpa.AssetEntity</class>

    <properties>
    </properties> 
    
  </persistence-unit>
</persistence>

The mock JNDI Context looks like this:

/**
 * Mock JNDI context that is just NOOPs except
 * lookup always returns the DataSource injected via
 * the setDataSource static method.
 * Similar to LittleDriver - just a hack to try to get
 * hibernate to use our DataSource
 */
public class LittleContext implements javax.naming.Context {
    private static  DataSource dataSource = null;
    /**
     * HibernateProvider injects littleware data source at startup time as needed
     */
    public static void setDataSource( DataSource value ) {
        dataSource = value;
    }

    @Override
    public Object lookup(Name name) throws NamingException {
        return dataSource;
    }

    @Override
    public Object lookup(String string) throws NamingException {
        return dataSource;
    }

    @Override
    public void bind(Name name, Object o) throws NamingException {
        throw new UnsupportedOperationException("Not supported yet."); 
    }

    @Override
    public void bind(String string, Object o) throws NamingException {
        throw new UnsupportedOperationException("Not supported yet."); 
    }

    @Override
    public void rebind(Name name, Object o) throws NamingException {
        throw new UnsupportedOperationException("Not supported yet."); 
    }

    @Override
    public void rebind(String string, Object o) throws NamingException {
        throw new UnsupportedOperationException("Not supported yet."); 
    }

    @Override
    public void unbind(Name name) throws NamingException {
        throw new UnsupportedOperationException("Not supported yet."); 
    }

    @Override
    public void unbind(String string) throws NamingException {
        throw new UnsupportedOperationException("Not supported yet."); 
    }

    @Override
    public void rename(Name name, Name name1) throws NamingException {
        throw new UnsupportedOperationException("Not supported yet."); 
    }

    @Override
    public void rename(String string, String string1) throws NamingException {
        throw new UnsupportedOperationException("Not supported yet."); 
    }

    @Override
    public NamingEnumeration<NameClassPair> list(Name name) throws NamingException {
        throw new UnsupportedOperationException("Not supported yet."); 
    }

    @Override
    public NamingEnumeration<NameClassPair> list(String string) throws NamingException {
        throw new UnsupportedOperationException("Not supported yet."); 
    }

    @Override
    public NamingEnumeration<Binding> listBindings(Name name) throws NamingException {
        throw new UnsupportedOperationException("Not supported yet."); 
    }

    @Override
    public NamingEnumeration<Binding> listBindings(String string) throws NamingException {
        throw new UnsupportedOperationException("Not supported yet."); 
    }

    @Override
    public void destroySubcontext(Name name) throws NamingException {
        throw new UnsupportedOperationException("Not supported yet."); 
    }

    @Override
    public void destroySubcontext(String string) throws NamingException {
        throw new UnsupportedOperationException("Not supported yet."); 
    }

    @Override
    public Context createSubcontext(Name name) throws NamingException {
        throw new UnsupportedOperationException("Not supported yet."); 
    }

    @Override
    public Context createSubcontext(String string) throws NamingException {
        throw new UnsupportedOperationException("Not supported yet."); 
    }

    @Override
    public Object lookupLink(Name name) throws NamingException {
        throw new UnsupportedOperationException("Not supported yet."); 
    }

    @Override
    public Object lookupLink(String string) throws NamingException {
        throw new UnsupportedOperationException("Not supported yet."); 
    }

    @Override
    public NameParser getNameParser(Name name) throws NamingException {
        return getNameParser("");
    }

    @Override
    public NameParser getNameParser( String string) throws NamingException {
        return new NameParser(){

            @Override
            public Name parse( final String string) throws NamingException {
                return new Name(){
                    @Override
                    public Object clone() { return this; }
                    
                    @Override
                    public int compareTo(Object o) {
                        throw new UnsupportedOperationException("Not supported yet."); 
                    }

                    @Override
                    public int size() {
                        return 1;
                    }

                    @Override
                    public boolean isEmpty() {
                        return false;
                    }

                    @Override
                    public Enumeration<String> getAll() {
                        throw new UnsupportedOperationException("Not supported yet."); 
                    }

                    @Override
                    public String get(int i) {
                        return string;
                    }

                    @Override
                    public Name getPrefix(int i) {
                        throw new UnsupportedOperationException("Not supported yet."); 
                    }

                    @Override
                    public Name getSuffix(int i) {
                        throw new UnsupportedOperationException("Not supported yet."); 
                    }

                    @Override
                    public boolean startsWith(Name name) {
                        throw new UnsupportedOperationException("Not supported yet."); 
                    }

                    @Override
                    public boolean endsWith(Name name) {
                        throw new UnsupportedOperationException("Not supported yet."); 
                    }

                    @Override
                    public Name addAll(Name name) throws InvalidNameException {
                        throw new UnsupportedOperationException("Not supported yet."); 
                    }

                    @Override
                    public Name addAll(int i, Name name) throws InvalidNameException {
                        throw new UnsupportedOperationException("Not supported yet."); 
                    }

                    @Override
                    public Name add(String string) throws InvalidNameException {
                        throw new UnsupportedOperationException("Not supported yet."); 
                    }

                    @Override
                    public Name add(int i, String string) throws InvalidNameException {
                        throw new UnsupportedOperationException("Not supported yet."); 
                    }

                    @Override
                    public Object remove(int i) throws InvalidNameException {
                        throw new UnsupportedOperationException("Not supported yet."); 
                    }
                };

            }
        };
    }

    @Override
    public Name composeName(Name name, Name name1) throws NamingException {
        throw new UnsupportedOperationException("Not supported yet."); 
    }

    @Override
    public String composeName(String string, String string1) throws NamingException {
        throw new UnsupportedOperationException("Not supported yet."); 
    }

    @Override
    public Object addToEnvironment(String string, Object o) throws NamingException {
        throw new UnsupportedOperationException("Not supported yet."); 
    }

    @Override
    public Object removeFromEnvironment(String string) throws NamingException {
        throw new UnsupportedOperationException("Not supported yet."); 
    }

    @Override
    public Hashtable<?, ?> getEnvironment() throws NamingException {
        throw new UnsupportedOperationException("Not supported yet."); 
    }

    @Override
    public void close() throws NamingException {}

    @Override
    public String getNameInNamespace() throws NamingException {
        throw new UnsupportedOperationException("Not supported yet."); 
    }

    
    //---------------------------
    
    /**
     * Assign this to the "java.naming.factory.initial" system property
     * to make the LittleContext mock the initial context.
     */
    public static class Factory implements javax.naming.spi.InitialContextFactory {

        @Override
        public Context getInitialContext(Hashtable<?, ?> hshtbl) throws NamingException {
            return new LittleContext();
        }
        
    }
}

This is the JPA EntityManager guice Provider used in a standalone application:

@Singleton
public class HibernateProvider implements Provider<EntityManagerFactory> {

    private final DataSource dataSource;
    private final String dataSourceURL;
    private EntityManagerFactory emFactory = null;


    @Inject
    public HibernateProvider(@Named("datasource.littleware") DataSource dsource,
            @Named("datasource.littleware") String sDatasourceUrl) {
        dataSource = dsource;
        dataSourceURL = sDatasourceUrl;
    }


    @Override
    public EntityManagerFactory get() {
        if (null == emFactory) {
            LittleDriver.setDataSource( dataSource );
            LittleContext.setDataSource( dataSource );
            if ( null == System.getProperty(  "java.naming.factory.initial" ) ) {
                System.setProperty( "java.naming.factory.initial", LittleContext.Factory.class.getName() );
            }
            
            emFactory = Persistence.createEntityManagerFactory( "littlewarePU" );
        }
        return emFactory;
    }
}

Anyway - I barely know how to use JPA, so duplicate these hacks at your own risk. The code is online here for now (I'm always moving things around in that repo).

compiling typescript with rhino javascript engine

I spent way too long the last couple days patching the typescript compiler (tsc) to run with java's rhino javascript engine. I mentioned in an earlier post how my dell laptop died on me. I wound up buying an hp envy m4 laptop on clearance at BestBuy to replace it, but before that I did that I was goofing around for a couple days getting by with my Android phone and the old PowerBook G4 I pulled off the shelf that amazingly boot up for me. Anyway - I thought I'd try to get tsc running from the command-line. The compiler is javascript compiled from typescript code, so I first tried to build node from source, but node's build setup requires newer versions of python, make, and gcc than what the powerbook had, so then I got the idea to try to run tsc with rhino, since the powerbook did have java 1.5 installed (java 1.6+ ships with rhino and a jrunscript command line tool). Of course it didn't "just work", and I let myself get sucked into banging my head on it - even after I got the new laptop. Ugh.

Anyway - I eventually got tsc running with rhino (the patch listing is further below). The easy part of the project was implementing a rhino version of tsc's IIO interface for file IO. The rhino implementation just calls through to java.io classes, and tsc runs a few feature tests to figure out which javascript engine it's running under:

    if (typeof ActiveXObject === "function")
        return getWindowsScriptHostIO();
    else if (typeof require === "function")
        return getNodeIO();
    else if ( typeof java != "undefined" )
        return getRhinoIO();
    else
        return null; // Unsupported host

The IO code was straight forward; the painful part was working around rhino's quirks. The first quirk I ran into was that rhino appears to treat the names of java's primitive types as reserved words, so things like:
var byte = 0;
or option.short = "v";
are illegal. Fortunately - that only popped up a couple places in the tsc code, but it's an unfortunate "feature" for rhino to have.

Another problem I ran into was invoking "delete" on an instance of java.io.File. Javascript includes delete in its collection of reserved words, but it should be legal to include a "delete()" method on some class. Rhino's javascript grammar probably just needs some love. The workaround was to access the method via f["delete"]() instead of f.delete().

C:\Users\Reuben\Documents\Code\typescript\src\compiler
> node
> var Foo = function() { return this; }
undefined
> Foo.prototype.delete = function() { return "bla"; }
[Function]
> (new Foo()).delete();
'bla'

...


> C:\Users\Reuben\Documents\Code\typescript\src\compiler
> jrunscript
js> var Foo = function() { return this; }
js> Foo.prototype.delete = function() { return "bla"; }
script error: sun.org.mozilla.javascript.internal.EvaluatorException: missing name after . operator (<STN> at line number 1
js>

Another problematic feature of rhino is that it does not hide the distinction between javascript's string type (which tsc expects), and java's java.lang.String. I discovered that Rhino has methods for converting between java types and javascript types - including the String() method mentioned here:

    resolvePath: function (path) {
        return <string> String( (new java.io.File(path)).getCanonicalPath() );
    },

There were one or two other small rhino quirks to work out, but the big one that surprised me was that rhino's regular expression objects apparently don't respect javascript's normal scoping rules. The tsc compiler was failing under rhino with various undefined types that weren't properly pulled in via the file-reference comments (see section 9.1.1 in the typescript spec). I eventually had a test setup, and found rhino would load every other referenced file, so a tsc run with rhino had this output:

(1)Reading code from C:/Users/Reuben/Documents/Code/typescript/src/compiler/typescript.ts
Found code at C:/Users/Reuben/Documents/Code/typescript/src/compiler/typescript.ts
 file reference: diagnostics.ts
 file reference: nodeTypes.ts
 file reference: ast.ts
 file reference: astWalkerCallback.ts
 file reference: astLogger.ts
 file reference: base64.ts
 file reference: emitter.ts
 file reference: parser.ts
 file reference: scanner.ts
 file reference: scopeWalk.ts
 file reference: symbols.ts
 file reference: tokens.ts
 file reference: typeCollection.ts
 file reference: types.ts
 file reference: referenceResolution.ts
 file reference: incrementalParser.ts

The output with nodejs was:

   (1)Reading code from C:/Users/Reuben/Documents/Code/typescript/src/compiler/typescript.ts
   Found code at C:/Users/Reuben/Documents/Code/typescript/src/compiler/typescript.ts
    file reference: diagnostics.ts
    file reference: flags.ts
    file reference: nodeTypes.ts
    file reference: hashTable.ts
    file reference: ast.ts
    file reference: astWalker.ts
    file reference: astWalkerCallback.ts
    file reference: astPath.ts
    file reference: astLogger.ts
    file reference: binder.ts
    file reference: base64.ts
    file reference: sourceMapping.ts
    file reference: emitter.ts
    file reference: errorReporter.ts
    file reference: parser.ts
    file reference: printContext.ts
    file reference: scanner.ts
    file reference: scopeAssignment.ts
    file reference: scopeWalk.ts
    file reference: signatures.ts
    file reference: symbols.ts
    file reference: symbolScope.ts
    file reference: tokens.ts
    file reference: typeChecker.ts
    file reference: typeCollection.ts
    file reference: typeFlow.ts
    file reference: types.ts
    file reference: pathUtils.ts
    file reference: referenceResolution.ts
    file reference: precompile.ts
    file reference: incrementalParser.ts
    file reference: declarationEmitter.ts

Anyway, long story short, it turned out that the reference strings were each processed by a function with a regular expression, and rhino had this crazy behavior where regular expression objects appear to be global.

with rhino:

js> function doTest( s ) { var rx =  /^\s*(\/\/\/\s*/gim;
return (rx.exec(s) == null); }

js> doTest(comment);
false
js> doTest(comment);
true
js> doTest(comment);
false
js> doTest(comment);
true

with node:
> function doTest(s) {
... var rx =  /^\s*(\/\/\/\s*/gim;
... return (rx.exec(s) == null);
... }
undefined
> comment
'///<reference path=\'sourceMapping.ts\' />'
> doTest(comment);
false
> doTest(comment);
false
> doTest(comment);
false
> doTest(comment);
false
> doTest(comment);
false

Unbelievable. Anyway - the work around is to reset the rx.lastIndex before each run, so:

    function getFileReferenceFromReferencePath(comment: string): IFileReference {
        var referencesRegEx = /^(\/\/\/\s*<reference\s+path=)('|")(.+?)\2\s*(static=('|")(.+?)\2\s*)*\/>/gim;
        referencesRegEx.lastIndex = 0;  // work around ridiculous bug in rhino ...
        var match = referencesRegEx.exec(comment);
        ...

Finally - I just tested this stuff by running the compiler on itself. The typescript repo on codeplex includes a bunch of test cases and an nmake based Makefile, but I was too lazy to download visual studio and get that working. In the end - rhino compiled tsc in 2 minutes, and node did it in 3 seconds. Ugh!

C:\Users\Reuben\Documents\Code\typescript\src\compiler
> date; jrunscript tsc.js --out tsc2.js tsc.ts; date

Monday, June 3, 2013 12:49:41 PM
Monday, June 3, 2013 12:51:39 PM


C:\Users\Reuben\Documents\Code\typescript\src\compiler
> date; node tsc2.js --out tsc3.js tsc.ts; date

Monday, June 3, 2013 12:58:40 PM
Monday, June 3, 2013 12:58:43 PM

Update 2013/06/29: I tried java 8's new nashorn javascript engine (in a jdk8 pre-release) to see how it did. Nashorn currently runs the tsc compile about 10% faster than rhino - still a lot slower than node. Doh!

> date; & 'C:\Program Files\Java\jdk1.8.0\bin\jrunscript.exe' .\tsc2.js --out tsc2.js tsc.ts; date;

Saturday, June 29, 2013 5:29:11 PM
Saturday, June 29, 2013 5:30:57 PM

Anyway - I'll check to see if the typescript maintainers will accept this patch, but I'll be surprised if they want anything to do with rhino after reading this sad tale ...

diff --git a/src/compiler/base64.ts b/src/compiler/base64.ts
index ee2d3c5..b4fc315 100644
--- a/src/compiler/base64.ts
+++ b/src/compiler/base64.ts
@@ -67,20 +67,21 @@ module TypeScript {
 
             var shift = 0;
             for (var i = 0; i < inString.length; i++) {
-                var byte = Base64Format.decodeChar(inString[i]);
+                // note: "byte" is reserved in java Rhino javascript environment - ugh
+                var bite = Base64Format.decodeChar(inString[i]);
                 if (i === 0) {
                     // Sign bit appears in the LSBit of the first value
-                    if ((byte & 1) === 1) {
+                    if ((bite & 1) === 1) {
                         negative = true;
                     }
-                    result = (byte >> 1) & 15; // 1111x
+                    result = (bite >> 1) & 15; // 1111x
                 } else {
-                    result = result | ((byte & 31) << shift); // 11111
+                    result = result | ((bite & 31) << shift); // 11111
                 }
 
                 shift += (i == 0) ? 4 : 5;
 
-                if ((byte & 32) === 32) {
+                if ((bite & 32) === 32) {
                     // Continue
                 } else {
                     return { value: negative ? -(result) : result, rest: inString.substr(i + 1) };
diff --git a/src/compiler/io.ts b/src/compiler/io.ts
index a5eb1ad..6e75bf2 100644
--- a/src/compiler/io.ts
+++ b/src/compiler/io.ts
@@ -13,6 +13,9 @@
 // limitations under the License.
 //
 
+declare var arguments:any;
+var javaArgs:any = arguments; // Rhino sets global arguments ... bla
+
 interface IResolvedFile {
     content: string;
     path: string;
@@ -105,7 +108,10 @@ declare class Enumerator {
     constructor (o: any);
 }
 declare function setTimeout(callback: () =>void , ms?: number);
+
 declare var require: any;
+declare var java: any;
+
 declare module process {
     export var argv: string[];
     export var platform: string;
@@ -123,7 +129,7 @@ declare module process {
 }
 
 var IO = (function() {
-
+    
     // Create an IO object for use inside WindowsScriptHost hosts
     // Depends on WSCript and FileSystemObject
     function getWindowsScriptHostIO(): IIO {
@@ -533,12 +539,251 @@ var IO = (function() {
             },
             quit: process.exit
         }
-    };
+    }
+    ;
+        
+    
+    function getRhinoIO():IIO {
+        var utf8 = java.nio.charset.Charset.forName( "UTF-8" );
+        var jscriptArgs = [];
+   
+        for( var i=0; i < javaArgs.length; ++i ) {
+            //
+            // convert java string to javascript string (so javascript string methods work - ugh!)
+            // see https://groups.google.com/forum/?fromgroups#!topic/mozilla.dev.tech.js-engine.rhino/FV15_KJVLGM
+            //
+            jscriptArgs.push( String( javaArgs[i] ) );
+        }
+        
+        
+        /**
+         * Byte-order-mark detector - ugh.
+         * @param streamInn java.io.InputStream
+         * @return java.io.Reader
+         * @see http://blog.publicobject.com/2010/08/handling-byte-order-mark-in-java.html
+         */
+       function inputStreamToReader(streamIn) {
+         // buffered stream supports mark and reset
+         var stream = new java.io.BufferedInputStream( streamIn );
+         stream.mark(3);
+         var byte1 = stream.read();
+         var byte2 = stream.read();
+         if (byte1 == 0xFF && byte2 == 0xFE) {
+           return new java.io.InputStreamReader(stream, "UTF-16LE");
+         } else if (byte1 == 0xFF && byte2 == 0xFF) {
+           return new java.io.InputStreamReader(stream, "UTF-16BE");
+         } else {
+           var byte3 = stream.read();
+           if (byte1 == 0xEF && byte2 == 0xBB && byte3 == 0xBF) {
+             return new java.io.InputStreamReader(stream, "UTF-8");
+           } else {
+             stream.reset();
+             return new java.io.InputStreamReader(stream);
+           }
+         }
+       };
+
+          return {
+            readFile: function (file):string {
+                try  {
+                    var f = new java.io.File( file );
+                    if( (! f.exists()) || (! f.isFile()) ) { return ""; }
+                    var buffer = java.lang.reflect.Array.newInstance( java.lang.Character.TYPE, f.length() + 128 ); // 128 fudge
+                    var reader = new java.io.BufferedReader( 
+                       inputStreamToReader(
+                              new java.io.FileInputStream( f ) 
+                         ) 
+                    );
+                    try {
+                     var offset = 0;
+                        for( var step = reader.read( buffer, offset, buffer.length - offset ); 
+                             step >= 0; step = reader.read( buffer, offset, buffer.length - offset ) ) {
+                             offset += step;
+                             //java.lang.System.out.println( "Just read num bytes: " + step );
+                        }
+                        var javaString = new java.lang.String( buffer, 0, offset )
+                        //java.lang.System.out.println( "Read: " + javaString );
+                        // convert java string to javascript string ... ugh
+                        return <string> String( new java.lang.String( buffer, 0, offset ) );
+                    } catch (ex) { 
+                        reader.close();
+                        ex.printStackTrace( java.lang.System.err );
+                        throw ex; 
+                    }
+                } catch (e) {
+                    IOUtils.throwIOError("Error reading file \"" + file + "\" - " + e.toString(), e );
+                }
+            },
+            writeFile: function( path, content ) {
+               var f = new java.io.File( path );
+               if( f.exists() && f.isFile() ) {
+                   var writer = new java.io.OutputStreamWriter(
+                         new java.io.FileOutputStream( f ), utf8
+                    );
+                    writer.write( content );
+                    writer.close();
+               }
+            },
+            deleteFile: function (path) {
+               var f = new java.io.File( path );
+               if( f.exists() && f.isFile() ) {
+                   // delete is reserved in javascript - confused Rhino parser - ugh
+                   f["delete"]();
+                }
+            },
+            fileExists: function (path) {
+                var result:bool = (new java.io.File( path )).exists();
+                return result;
+            },
+            createFile: function (path, useUTF8?) {
+                var f = new java.io.File( path );
+                if ( f.exists() && (! f.isFile()) ) {
+                    IOUtils.throwIOError("Error creating file \"" + path + "\".", null ); 
+                } else if ( ! f.exists() ) {
+                    var dir = f.getParentFile();
+                    dir.mkdirs();
+                }
+                try  {
+                    var writer = new java.io.OutputStreamWriter(
+                             new java.io.FileOutputStream( f ), utf8
+                            );
+                } catch (e) {
+                    IOUtils.throwIOError("Couldn't write to file '" + path + "'.", e);
+                }
+                return new IOUtils.BufferedTextWriter( {
+                    Write: function (str:string ) {
+                        writer.write( str );
+                    },
+                    WriteLine: function (str:string) {
+                        writer.write( str + "\n" );
+                    },
+                    Close: function () {
+                        writer.close();
+                        writer = null;
+                    }
+                } );
+            },
+            dir: function dir(path, spec?, options?):string[] {
+                options = options || {
+                };
+                function filesInFolder(folder:any):string[] {
+                    var paths = [];
+                    var files = folder.listFiles();
+                    for(var i = 0; i < files.length; i++) {
+                        var f = files[i];
+                        if(options.recursive && f.isDirectory()) {
+                            paths = paths.concat(filesInFolder(f));
+                        } else if(f.isFile() && (!spec || f.getName().match(spec))) {
+                            paths.push( String( f.getPath() ) ); // convert to javascript String
+                        }
+                    }
+                    return paths;
+                }
+                return filesInFolder( new java.io.File( path ) );
+            },
+            createDirectory: function (path) {
+                try  {
+                    if(!this.directoryExists(path)) {
+                       (new java.io.File( path )).mkdirs();
+                    }
+                } catch (e) {
+                    IOUtils.throwIOError("Couldn't create directory '" + path + "'.", e);
+                }
+            },
+            directoryExists: function (path) {
+                var f = new java.io.File( path );
+                var result:bool = f.exists() && f.isDirectory();
+                return result;
+            },
+            resolvePath: function (path) {
+                return <string> String( (new java.io.File(path)).getCanonicalPath() );
+            },
+            dirName: function (path) {
+                return <string> String( (new java.io.File( path )).getCanonicalFile().getParent() );
+            },
+            findFile: function (rootPath, partialFilePath) {
+                var scan = new java.io.File( rootPath + "/" + partialFilePath ).getCanonicalFile();
+                while(true) {
+                    if( scan.exists() ) {
+                        try  {
+                            var content = this.readFile( scan.getPath() );
+                            return {
+                                content: <string> content,
+                                path: <string> String( scan.getPath() )
+                            };
+                        } catch (err) {
+                        }
+                    } else {
+                        // climb up the file system ... ?
+                        var parent = (new java.io.File( rootPath )).getParent();
+                        if( parent == null ) {
+                            return null;
+                        } else {
+                            scan = new java.io.File( parent, partialFilePath );
+                        }
+                    }
+                }
+            },
+            print: function (str) {
+                java.lang.System.out.print( str );
+            },
+            printLine: function (str) {
+                java.lang.System.out.println( str );
+            },
+            arguments: <string[]> jscriptArgs, 
+            stderr: {
+                Write: function (str) {
+                    java.lang.System.err.print(str);
+                },
+                WriteLine: function (str) {
+                    java.lang.System.err.println(str );
+                },
+                Close: function () {
+                }
+            },
+            stdout: {
+                Write: function (str) {
+                    java.lang.System.out.print(str);
+                },
+                WriteLine: function (str) {
+                    java.lang.System.out.println(str );
+                },
+                Close: function () {
+                }
+            },
+            
+            /**
+             * Could implement watchFile() with java-7 nio2 code, but too lazy to bother,
+             * since WindowsScriptHost skips this method too ... :)
+             * @see http://docs.oracle.com/javase/tutorial/essential/io/notification.html 
+             */
+            watchFile: null,
+            run: function(source, filename) {
+                try {
+                    eval(source);
+                } catch (e) {
+                    IOUtils.throwIOError("Error while executing file '" + filename + "'.", e);
+                }
+            },
+            getExecutingFilePath: function () {
+                return this.arguments[0];
+            },
+            quit: function (exitCode? : number = 0) {
+                try {
+                    java.lang.System.lang.exit(exitCode);
+                } catch (e) {
+                }
+            }
+        };
+    }
+    ;
 
     if (typeof ActiveXObject === "function")
         return getWindowsScriptHostIO();
     else if (typeof require === "function")
         return getNodeIO();
+    else if ( typeof java != "undefined" )
+        return getRhinoIO();
     else
         return null; // Unsupported host
 })();
diff --git a/src/compiler/optionsParser.ts b/src/compiler/optionsParser.ts
index a10fb8f..7a7eb73 100644
--- a/src/compiler/optionsParser.ts
+++ b/src/compiler/optionsParser.ts
@@ -18,7 +18,7 @@
 interface IOptions {
     name?: string;
     flag?: bool;
-    short?: string;
+    shorty?: string;  // note: "short" is reserved in java
     usage?: string;
     set?: (s: string) => void;
     type?: string;
@@ -34,7 +34,7 @@ class OptionsParser {
 
         for (var i = 0; i < this.options.length; i++) {
 
-            if (arg === this.options[i].short || arg === this.options[i].name) {
+            if (arg === this.options[i].shorty || arg === this.options[i].name) {
                 return this.options[i];
             }
         }
@@ -89,8 +89,8 @@ class OptionsParser {
             var usageString = "  ";
             var type = option.type ? " " + option.type.toUpperCase() : "";
 
-            if (option.short) {
-                usageString += this.DEFAULT_SHORT_FLAG + option.short + type + ", ";
+            if (option.shorty) {
+                usageString += this.DEFAULT_SHORT_FLAG + option.shorty + type + ", ";
             }
 
             usageString += this.DEFAULT_LONG_FLAG + option.name + type;
@@ -110,27 +110,27 @@ class OptionsParser {
         }
     }
 
-    public option(name: string, config: IOptions, short?: string) {
+    public option(name: string, config: IOptions, shorty?: string) {
         if (!config) {
-            config = <any>short;
-            short = null;
+            config = <any>shorty;
+            shorty = null;
         }
 
         config.name = name;
-        config.short = short;
+        config.shorty = shorty;
         config.flag = false;
 
         this.options.push(config);
     }
 
-    public flag(name: string, config: IOptions, short?: string) {
+    public flag(name: string, config: IOptions, shorty?: string) {
         if (!config) {
-            config = <any>short;
-            short = null;
+            config = <any>shorty;
+            shorty = null;
         }
 
         config.name = name;
-        config.short = short;
+        config.shorty = shorty;
         config.flag = true
 
         this.options.push(config);
diff --git a/src/compiler/precompile.ts b/src/compiler/precompile.ts
index 88adf32..c66f937 100644
--- a/src/compiler/precompile.ts
+++ b/src/compiler/precompile.ts
@@ -131,6 +131,7 @@ module TypeScript {
 
     function getFileReferenceFromReferencePath(comment: string): IFileReference {
         var referencesRegEx = /^(\/\/\/\s*<reference\s+path=)('|")(.+?)\2\s*(static=('|")(.+?)\2\s*)*\/>/gim;
+        referencesRegEx.lastIndex = 0;  // work around ridiculous bug in rhino ...
         var match = referencesRegEx.exec(comment);
 
         if (match) {
@@ -294,6 +295,7 @@ module TypeScript {
             
             if (!comment.isBlock) {
                 var referencedCode = getFileReferenceFromReferencePath(comment.getText());
+                //CompilerDiagnostics.debugPrint( "Considering comment as possible reference (" + (referencedCode ? "ok" : "no") + "): " + comment.getText() );
                 if (referencedCode) {
                     referencedCode.minChar = comment.startPos;
                     referencedCode.limChar = referencedCode.minChar + comment.value.length;
diff --git a/src/compiler/referenceResolution.ts b/src/compiler/referenceResolution.ts
index 442d8ec..52ae47c 100644
--- a/src/compiler/referenceResolution.ts
+++ b/src/compiler/referenceResolution.ts
@@ -102,7 +102,7 @@ module TypeScript {
                 // if the path is relative, or came from a reference tag, we don't perform a search
                 if (isRelativePath || isRootedPath || !performSearch) {
                     try {
-                        CompilerDiagnostics.debugPrint("   Reading code from " + normalizedPath);
+                        CompilerDiagnostics.debugPrint("   (1)Reading code from " + normalizedPath);
                             
                         // Look for the .ts file first - if not present, use the .ts, the .d.str and the .d.ts
                         try {
@@ -116,19 +116,19 @@ module TypeScript {
                                 else if (isTSFile(normalizedPath)) {
                                     normalizedPath = changePathToSTR(normalizedPath);
                                 }
-                                CompilerDiagnostics.debugPrint("   Reading code from " + normalizedPath);
+                                CompilerDiagnostics.debugPrint("   (2)Reading code from " + normalizedPath);
                                 resolvedFile.content = ioHost.readFile(normalizedPath);
                             }
                             catch (err) {
                                 normalizedPath = changePathToDSTR(normalizedPath);
-                                CompilerDiagnostics.debugPrint("   Reading code from " + normalizedPath);
+                                CompilerDiagnostics.debugPrint("   (3)Reading code from " + normalizedPath);
 
                                 try {
                                     resolvedFile.content = ioHost.readFile(normalizedPath);
                                 }
                                 catch (err) {
                                     normalizedPath = changePathToDTS(normalizedPath);
-                                    CompilerDiagnostics.debugPrint("   Reading code from " + normalizedPath);
+                                    CompilerDiagnostics.debugPrint("   (4)Reading code from " + normalizedPath);
                                     resolvedFile.content = ioHost.readFile(normalizedPath);
                                 }
                             }
@@ -148,7 +148,10 @@ module TypeScript {
 
                     // if the path is non-relative, we should attempt to search on the relative path
                     resolvedFile = ioHost.findFile(parentPath, normalizedPath);
-
+                    CompilerDiagnostics.debugPrint("   Attempting to resolve (" + parentPath + ", " + normalizedPath + ") got: " + 
+                         (resolvedFile == null) ? "null" : resolvedFile.path 
+                    );
+                    
                     if (!resolvedFile) {
                         if (isSTRFile(normalizedPath)) {
                             normalizedPath = changePathToTS(normalizedPath);
@@ -187,6 +190,10 @@ module TypeScript {
                     var resolvedFilePath = ioHost.resolvePath(resolvedFile.path);
                     sourceUnit.referencedFiles = preProcessedFileInfo.referencedFiles;
 
+                    for (var i = 0; i < preProcessedFileInfo.referencedFiles.length; i++) {
+                        var fileReference = preProcessedFileInfo.referencedFiles[i];
+                        CompilerDiagnostics.debugPrint("    file reference: " + fileReference.path);
+                    }
                     // resolve explicit references
                     for (var i = 0; i < preProcessedFileInfo.referencedFiles.length; i++) {
                         var fileReference = preProcessedFileInfo.referencedFiles[i];

Updating Web-login for Javascript Webapp

I've been coding away for several days on some old web-login logic I had implemented in littleware to work in web applications with JSF-managed UX. I'm updating the code for use in apps where a javascript program manages the user experience. I've been thinking lately about the similarities and differences between the two application architectures.

The first difference between the two designs is in deployment. The old JSF architecture relied on JSF and JSP templates managed by the server, so I would usually bundle up the entire application in a .war file, and deploy it to some glassfish or tomcat or whatever container. The user interacted with the application by clicking links and submitting forms that moved the browser between web pages rendered by the server.

I'm trying to structure the newer code so that most client-side assets (javascript, CSS, hadlebar templates, ...) are served as static files from S3. The user's in-browser interactions with the application trigger events that are handled by javascript event-handlers. The javascript code running in the user's browser can access remote services via cross-origin AJAX requests. There are various CORS servlet filters open sourced online that take care of setting the HTTP response headers that browsers look for; today I grabbed this one posted by some Ebay coders to github - hopefully it works.

In the login code, both the old and new setups rely on a request filter (javax.servlet.Filter) to intercept unauthenticated client requests. The old code would intercept an unauthenticated page-load request, and forward the request on the server to a login page via RequestDispatcher.forward.

The new code intercepts unauthenticated AJAX requests to JSON services, and responds to the javascript client with an HTTP 401 (unauthorized) response, and relies upon the javascript code on the client to initiate a login process that eventually authenticates with the server by submitting credentials to a login AJAX service.

Finally - in the older applications I had the bad habit of tracking session state on the server via beans stashed in container-managed in-memory session. Tracking user data in-memory on a particular server required that a client continued to interact with the same server it began a session with. In-memory session state also made it difficult to partition a server's functionality between different endpoints. In other words - if I had a server that implemented some functionality "ABC", and I later decided that I would like to split the functionality on that server (or server cluster) between separate "A", "B", and "C" servers (or clusters), then it would be hard to do that if the code relied on shared in-memory session state.

Anyway, the new code avoids session state on the server - instead it relies on the client-side javascript code to track session state in most cases, and transient cookies in a few others.

In the end - I get to throw away a bunch of crazy server-side JSF beans and templates, and replace them with javascript modules and REST services.

Extra S3 log parameters with AWS Java SDK

Amazon web services' S3 REST API supports custom access log information by adding custom query string parameters beginning with "x-" that S3 ignores but logs. Unfortunately custom query parameters are not directly supported in the AWS Java SDK, so we were planning to drop down to writing HTTP REST code for a recent project that required logging of some custom client-session parameters.

I hate working with HTTP, so I was glad when we figured out a workaround. The trick we came up with was to register a custom RequestHandler with our instance of the SDK's AmazonS3Client. The RequestHandler is an internal class in the API, so it's not included in the API documentation, but you can download the source code to see its simple interface:

/**
 * Interface for addition request handling in clients. A request handler is
 * executed on a request object before it is sent to the client runtime
 * to be executed.
 */
public interface RequestHandler {

    /**
     * Runs any additional processing logic on the specified request (before it
     * is executed by the client runtime).
     *
     * @param request
     *            The low level request being processed.
     */
    public void beforeRequest(Request request);

 /**
  * Runs any additional processing logic on the specified request (after is
  * has been executed by the client runtime).
  *
  * @param request
  *            The low level request being processed.
  * @param response
  *            The response generated from the specified request.
  * @param timingInfo
  *            Timing information on the request's processing.
  */
    public void afterResponse(Request request, Object response, TimingInfo timingInfo);

 /**
  * Runs any additional processing logic on a request after it has failed.
  *
  * @param request
  *            The request that generated an error.
  * @param e
  *            The error that resulted from executing the request.
  */
    public void afterError(Request request, Exception e);

}

So the RequestHandler's beforeRequest method can add parameters to a Request before it is processed by the underlying HTTP engine. The only trick is to determine which parameters to add to a particular Request, but it's easy to extend the SDK's API-level request objects (like S3's GetObjectRequest) with subtypes that add application-specific properties, then check for for those subtypes in the RequestHandler via the getOriginalRequest accessor.

Oracle Google Comments

For some reason I was inspired today to post a comment on the NYTimes Bits bLog's post on the Oracle-Google lawsuit. I thought I didn't make it through the Time's idiot filter, but they actually put my comment online. Crazy. Here it is again:

---

I think Google got itself into trouble, because rather than simply build on top of java (write code with the java language and libraries), and contribute to the java community; Google decided to "fork" java to make its own language that is nearly identical to java, but with various differences (security model, libraries, bytecode) at a time (pre-openJDK) that java was not open sourced. Often non-UI code (networking, database, ...) written in java can be easily recompiled for Android's "Dalvik" runtime, so Google gained instant access to the java developer community and programming tools; but the two systems are not the same.

There's something slimy about what Google did - forking java for Android without respecting the time and money Sun invested. Sun Micro sued Microsoft years ago when Microsoft released a version of java with incompatibilities to improve java on windows. Google was very careful to never call Android's runtime "java" to avoid the issues Microsoft ran into, but everybody thinks of Android as running java. Google should have just bought Sun Micro when it had the chance ...

Oracle is slimy too for trying to insinuate itself into the Android smart phone and tablet market. Oracle and Sun didn't have the vision of Apple, or the skill to imitate Apple quickly like Google; so now Oracle is trying to sue its way into the market.

Anyway - the best outcome when two corporate monsters fight is that they both get cut up and bleed ... ;-)

Simple Session Scope with Guice

I've been a big fan of the Guice dependency injection library for a while, but I missed support for session-scoped injection until I figured out a way to achieve the same effect using child injectors. I was inspired by the PicoContainer project that I stumbled upon several months ago. I haven't actually used PicoContainer, but it appears to actually be better thought out than Guice - implementing arbitrary dependency injection scopes and lifecycle management via hierarchies of IOC containers.

I had PicoContainer's hierarchy approach bouncing around in my head when I stumbled up Guice's createChildInjector method - which supports a similar approach to managing object scopes.

Long story short - I introduced the notion of a "SessionModule" that defines session-scoped bindings to littleware's module system in my development repository clone. Littleware's module system also uses OSGi in an unorthodox way to manage the application life cycle. I wish I would have known about PicoContainer earlier - it appears to implement a nice approach for a combined IOC and application life cycle container. At some point I need to take a look at Spring too - to steal ideas if nothing else!

Escaping Java classpath wildcard on Windows command line!

I had a ridiculous battle with a set of .bat scripts that I wrote to launch java command line applications on Windows. I'm working on a suite of related little tools that I bundle into a zip file with a bunch of .jar files under a /lib/ folder, and launch scripts under a /bin/ folder that each look something like this:

@echo off

if not defined JAVACMD set JAVACMD=java.exe
if defined JAVA_HOME set JAVACMD="%JAVA_HOME%\bin\java.exe"

%JAVACMD% "-Djava.util.logging.config.file=%~dps0..\config\logging.properties" -cp "%~dps0..\lib\*" run.my.App %*

So I'm trying to use the nifty java classpath * wildcard introduced with java 6, but I had a terrible time with windows insisting on expanding /lib/* in the shell regardless of how I tried to quote or escape the thing! I was driving myself crazy, when I finally got the genious idea to just add a semicolon, so /lib/*; doesn't look like a path to Windows Powershell or CMD (I guess), and the following works:

@echo off

if not defined JAVACMD set JAVACMD=java.exe
if defined JAVA_HOME set JAVACMD="%JAVA_HOME%\bin\java.exe"

%JAVACMD% "-Djava.util.logging.config.file=%~dps0..\config\logging.properties" -cp "%~dps0..\lib\*;" run.my.App %*

What an amazingly stupid waste of time!