## Friday, March 29, 2013

### Cucumber with fun

i'm a big fan of BDD and we are using cucumber-jvm on the server side. The normal BDD template is
Given something
And something else
When I do this
And I do that too
Then something good happens

And if you put this at the beginning of your feature file
# language : en-pirate

you can do this

Gangway! something
Aye something else
Blimey! I do this
Aye I do that too
Let go an haul something good happens

Interesting!

The only thing is the locale en-pirate isn't really documented nicely (at least i couldn't find any documentation) and it's not that intuitive either. I'd expect it to be en_pirate as in en_US. I have to trace down the code and found the regular expression they use to match the locale to find out it should be a - instead of a _.

## Thursday, March 28, 2013

### Registering a POJO as a Spring Bean

It's indeed part of the Dynamic Service Activator.  In it, we need to programmatically create a channel and register that to Spring application context so the router can route to that channel (it will look up the name of the channel from the application context.)  It's surprising easy to do that, a one liner!

### Using ZooKeeper

We are using zookeeper to keep our configuration and when the configuration is updated, we'll be notified and we can update/restart the related module.  To do that, we leverage the watch feature of zookeeper.  And Yan in his blog stated very clear the things to watch for when using ZooKeeper's watch.
"

1. Watches are one time triggers; if you get a watch event and you want to get notified of future changes, you must set another watch.
2. Because watches are one time triggers and there is latency between getting the event and sending a new request to get a watch you cannot reliably see every change that happens to a node in ZooKeeper. Be prepared to handle the case where the znode changes multiple times between getting the event and setting the watch again. (You may not care, but at least realize it may happen.)
3. A watch object, or function/context pair, will only be triggered once for a given notification. For example, if the same watch object is registered for an exists and a getData call for the same file and that file is then deleted, the watch object would only be invoked once with the deletion notification for the file.
"

The problem he is trying to solve here is that when the node has been deleted and recreate right away, we will lost the event for the creation of the new node as both the parent level and the child level events are triggered (node deleted) and before we can registered a new watch, the node had been recreated and the event will be forever lost.

He had also posted a solution for this.  It's pretty straightforward (it's the troubleshooting that's hard),  the watcher for the parent level only deals with 'add' event and each child watcher try to watch the "deleted" node in case it has been recreated.

if you're not familar with scalar, here's the java version

Another thing to watch for when using ZooKeeper is the ZooKeeper object from new ZooKeeper() is not readily usable.  You will get a ConnectionLossException if you try to use it before the connection is established.  To avoid that, you'll have to watch for the connection events and wait for the status KeeperState.SyncConnected (that's event.getState().ordinal() == 3 in the process method).

## Wednesday, March 27, 2013

### EasyMock with Spring Beans (Spring Integration)

Creating mock beans in spring is really easy.

All you have to do is to declare a bean with easymock and set the interface you want to mock as the constructor.

<bean id="somethingCool" class="org.eashmock.EasyMock" factory-method="createMock" primary="true">
<constructor-arg value="com.mycompany.cool.SomethingCool/>
</bean>

and in the test, just autowired the bean and call expect & reply as usual.

This blog by DevGrok has detailed how that's done and more.

And when I'm try to mock an Spring Integration Gateway only to find that if the gateway is annotated with @Gateway, it can't be mocked.  Spring Integration somehow taken over the proxy and when I call, EasyMock.expect( someGateway.someMethod() ), it actually call Spring Integration and hung waiting for a reply message. I ended up mocking one of the service activator endpoints called by the gateway.

## Monday, March 25, 2013

### Spring custom namespace

The dynamic service activator that we created has a very clumsy definition.

it'd be nice if it's something like this

To do that we need to create a custom namespace for spring and we can have our bean definition under beans. I found this blog by carlo scarioni detailing how to do that.  Following it, I was able to create my namespace and put in under beans.  However, it is not added to the application context.

For that, I followed Spring's doc, all i have to do is
1. the xsd needs to import spring beans and the element needs to extend beans:identifiedType.
2. the bean definition parser should extends AbstractSingleBeanDefinitionParser instead.
everything else is the same.  but now you'll have id attribute in your bean definition (from beans:identifiedType)!  and it will be added to the application context.

Another cool thing we can use is to use spring tool so you can verify the bean ref is of a certain class.  Import the following namespace and add the annotation to your attribute.

<xs:import namespace="http://www.springframework.org/schema/tool" />

below is the gist we used to parse our custom tag. note that it set the scope to prototype at the end and it also shows you how to pass an array of beans.

### Spring Integration Gateway

Gateway is very handy for communicating between modules.  However, it has a side effect that all headers not specified in the gateway will be lost to those behind the gateway.  i.e. it will only copy those headers that is listed/annotated in the method arguments.

check GatewayMethodInboundMessageMapper.mapArgumentsToMessage.  Here it construct the message sent into the request channel and it only copy those headers that is in the argument.

But come to think of it, if endpoints behind gateway needs to use a specific header, it's not suppose to know the structure of the message, it should be specified as an input parameter to the gateway method.  It's just that we're developing both the module that calls the gateway and those behind the gateway, we kinda expect the headers will be carried into and behind the gateway.

## Sunday, March 24, 2013

### JBoss OSGi doesn't export Log4j SPI

We are using spring-rabbit and others than 1.0.0.RELEASE, it imports org.apache.log4j.spi package.  However, JBoss OSGi (at least 7.1.1.Final) doesn't export that.  A workaround is to get log4j and build a wrapper just to export the spi package.

### Create Apache Shell Command to check Gemini Blueprint Service

One of the annoying thing in using Eclipse Gemini is that if a dependency service is not available, it will wait for 5 mins (default) and threw timeout exception.  and even if the application context is not created (because of the timeout), the bundle's status is still active.  So I have decided to build a simple command to Apache Shell so that I can find out if there's any unsatisfied dependencies using Apache Felix WebConsole.

First we need to build a fragment bundle to gemini blueprint extender by adding this to the bundle's manifest.mf

Fragment-Host: org.eclipse.gemini.blueprint.extender

Next create a class extending OsgiBundleApplicationContextListener

in the onOsgiApplicationEvent, simply build a map to store all service dependency status.  Since it's collecting event data (and that it is a fragment), so the bundle have to be installed before starting the blueprint extender and other bundles that you want to capture the events.

and build another bundle which implements Apache Shell's Command and simply call the last bundle and prints out the result.

My command's name is "geministatus" (just return "geministatus" in the getName method of  your Command) so when you navigate to the shell tab of your felix webconsole, you can type geministatus and you'll find out if any bundles is waiting for any services to start the application context.

### Scripting in Redis

Since Redis 2.6, it introduced scripting and is surprisingly easy.  It is using LUA 5.1 which I have never came across before but i can learn the basic syntax in an hour or so.

We are trying to create a cache that still has O(1) when retrieve entry with a certain id while maintaining the order of the entries.  Basically, we want a cache with feature of a hash and a list, so we decided to build a virtual cache where actually, it is implemented by a list cache an a hash cache.

when adding an entry to the cache, we'll have to add the id to the end of the list if it's not already in the list and put the (id,entry) pair to the hash.  In order to do that in an atomic fashion, we have to use script*.

the script look like this.

you can call any redis api using redis.call.  Notice the space after do, then and end, that's there because we're concatenating the strings without a space, it'll join with the next line's first command.

To call the script using RedisTemplate (with Jedis as connection factory), you'll have to get the native connection (Jedis) and use Jedis.eval to execute the script.

also, you can test your script using redis-cli directly.  Please note that the syntax is ./redis-cli --eval <script name> <number of key> <keys>... , <argv>...
e.g. ./redis-cli --eval test.lua 1 x , 1 2
in the script, you can do
local key = KEYS[1]
local test1 = ARGV[1]
local test2 = ARGV[2]
and the comma has to have a space before and after it.  neither x, 1 2 nor x ,1 2 will work.

* multi/exec can't do what we wanted to do because command inputs cannot depends on result from previous commands.

### Raise condition when creating bean in OSGi managed property callback

Our application had been suffering with mysterious problem that some of the OSGi services are not registered and just by restarting the server, you'll have a 50-50 chance that it'll all start up.  It has been bothering us for a few months.  One of my team's engineer finally spotted two things.

1. the bundle not registering the service registered some other services.
2. application context of that bundle is not registered as an OSGi service (it can be turned off but in our environment, it's on)
3. it hangs in applicationContext.getBean where we are trying to get a prototype bean when a new configuration is available.
and the updateConfig method has applicationContext.getBean in it.

so what happened is when indexConfigMgr is being created, it acquired a lock to create bean and call Config Admin to get configuration which also requires acquiring a lock.  Meanwhile, in another thead, the Config Admin is also trying to call the update method on indexConfigMgr which it will first acquired the lock to get configuration and inside the update method, we tried to create a new bean which tries to acquire the create bean lock.  thus, a classic dead lock.

The solution is pretty straightforward, just start a new thread in the updateConfig so the bean creation will be executed in another thread.

### Creating Spring Integration Service Activator dynamically

My project connects to multiple backend services and we have created a Connector bean for each of the backend services and they all implemented the same interface.  The way we create those Connector beans is using OSGi Config Admin, i.e. we define a configuration for each backend services and Config Admin will create an instance of Connector and registered that to OSGi service registry.
Let's say the Connector interface has two methods,

Services getAllService()
Service getService(String id)

what we wanted to do is to set a router that would
1. route to all available Connector for the getAllService call and have an aggregator to aggregate the results from all Connector.
2. route to a specific Connector for getService (assuming we can tell which Connector to use by inspecting the id)
The problem is I cannot define service activator or gateway using XML as it's configuration driven.  I've looked into Spring Integration source and determine it's too complicated to try to create a gateway or a service activator programatically.

Inspired by this post, we decided to build our own dynamic service activator.   The router will route to channels with a certain name pattern, <backend service name>.<method name>, e.g. backendA.getAllService.  Then we create a bean, DynamicServiceActivator, that will create channels with matching names and call the Connector bean.  Details about how to create a channel and send a reply is already covered in the above mentioned post, I'm not repeating here.  Since we'll need one instance of DynamicServiceActivator per Connector bean, we get a list of Connector using Gemini's list

<osgi:list interface="Connector">
<osgi:listener bind-method="addConnector" unbind-method="removeConnector" ref="connectorMgr" />
</osgi:list>

<bean id="dynamicServiceActivator" class="DynamicServiceActivator" scope="prototype"/>

and in the addConnector method, all we have to do is applicationContext.getBean("dynamicServiceActivator") and set the Connector to the activator.

there's one little piece is missing from the above picture.  Since we are creating a channel per method, service activator is suppose to call one method, when we set the connector to the dynamic service activator, it'll have to inspect all method names and create channels for each one of them.  Two ways we can control the method to be exposed, either define in the application context xml, e.g.

<bean id="dynamicServiceActivator" class="DynamicServiceActivator" scope="prototype">
<property name="methods">
<map>
<entry><key>getAllService</key><value>SpEL expression</value></entry>
<entry><key>getService</key><value>SpEL expression</value></entry>
</map>
</property>
</bean>

or annotate the Connector class, so we can find the appropriate method signature to call.

### Sequence Diagram

We are using UML to communicate designs and sometime you'll want to have it drawn out nicely (yes, i do need to work on my penmanship.) and i stumbled upon http://www.websequencediagrams.com/. It's a really useful web site that we can just write all the interaction and it will generate a nice sequence diagram. It has all kinds of plugin, confluence, eclipse, intellij, maven so you can use it in your favorite editor. Then I came across PlantUML, http://plantuml.sourceforge.net/, which the syntax for the sequence diagram is highly deived from websequencediagram.com but it supports a whole lot more!

## Monday, February 18, 2013

### Create Aggregatable Maven Report Plugin

There are some good examples, like this and this, however they all use javadoc style and didn't include the complete pom file, nor include aggregator.

The packaging maven-plugin is to instruct maven that it is a maven plugin and thus will look for the plugin.xml in META-INF.  The maven-plugin-plugin in the build is to generate the plugin.xml.  since I am using java annotation, we'll have to add maven-plugin-annotations to the dependencies.
Then I want to build a custom report so that it will generate the aggregated version only if the project has modules (to aggregated the reports of all its modules) and the normal report when the report has no modules. to do that, annotate MavenProject with @Component and the current project will be injected. Override the canGenerateReport so that either the aggregated version or the normal version will be generated.

the reactor projects is to get the module projects for aggregated as MavenProject.getModules only return the name of the module.
Finally to add that to your site report

## Wednesday, January 30, 2013

### Setting up Nginx for Socket.io Loadbalancing

This is basically the documentary for what i tried to use nginx to load balance socket.io.

## PCRE (Perl Compatible Regular Expressions)

[Unix] [http://sourceforge.net/projects/pcre/files/pcre/]
[Windows] [http://gnuwin32.sourceforge.net/packages/pcre.htm]
# extract the tarball
# ./configure
# make
# sudo make install (it'll install the library under /usr/local/lib)

## OpenSSL

# extract the tarball
# ./config
# make
# sudo make install

## Nginx

# extract the tarball
# ./configure \--with-http_ssl_module
# make
# sudo make install

### To start Nginx

# sudo LD_LIBRARY_PATH=/usr/local/lib /usr/local/nginx/sbin/nginx
[or] set LD_LIBRARY_PATH in environment
# open url [http://localhost] should get the default Nginx welcome page

Welcome to nginx\!

If you see this page, the nginx web server is successfully installed and working. Further configuration is required.

For online documentation and support please refer to nginx.org.
Commercial support is available at nginx.com.

Thank you for using nginx.

### Reference installation guide

[http://www.thegeekstuff.com/2011/07/install-nginx-from-source/] [http://nginx.org/en/docs/install.html]

### Enable SSL on Nginx

•  edit nginx.config, under server add
server {
listen 80;
listen 443 ssl;

ssl_certificate /some/location/ssl.crt;
ssl_certificate_key /some/location/privateKey.key;
ssl_protocols        SSLv3 TLSv1;
ssl_ciphers HIGH:!aNULL:!MD5;

server_name host;
• please note that this setup only works for normal http traffic but not socket.io traffic.  please refer to attempt 4 for the nginx.conf setup.

## Using Nginx as websocket reverse proxy

### Node.js setup

This is the sample socket.io example from http://socket.io

server.js
var app = require('express')()
, server = require('http').createServer(app)
, io = require('socket.io').listen(server);

var port = (typeof process.argv[2] !== 'undefined') ? process.argv[2] : 8080;
console.log( 'port ' + port );
server.listen(port);

app.get('/', function(req, res) {
res.sendfile(__dirname + '/index.html');
});

io.sockets.on('connection', function(socket) {
socket.emit('news', {hello: 'world'} );
socket.on('my other event', function(data) {
console.log(data);
});
});

#### index.html

<script src="/socket.io/socket.io.js"></script>
<script>
var socket = io.connect('https://host');
socket.on('news', function (data) {
console.log(data);
socket.emit('my other event', { my: 'data' });
});
</script>
note, https://host when testing SSL, http://host when testing without SSL.  you will get lots of warning messages on the browser if using http in the socket while the index.html is accessing through https.
The page at https://host/ displayed insecure content from http://host/socket.io/1/xhr-polling/S-vUnEsPSCzECUcZIITT?t=1359502588702.

### First attempt: forward websocket using Nginx 1.2.6 directly to Node.js

#### nginx.conf

server {
listen 80;
server_name host;
location / {
proxy_set_header X-Real-IP $remote_addr; proxy_set_header X-Forwarded-For$proxy_add_x_forwarded_for;
proxy_set_header  Host $host:9001; #probaby need to change this proxy_set_header Connection "Upgrade"; proxy_set_header Upgrade websocket; } #### Result req url:/ debug - destroying non-socket.io upgrade req url:/favicon.ico debug - destroying non-socket.io upgrade #### socket.io - manager.js Manager.prototype.handleUpgrade = function (req, socket, head) { var data = this.checkRequest(req) , self = this; if (!data) { if (this.enabled('destroy upgrade')) { socket.end(); this.log.debug('destroying non-socket.io upgrade'); } return; } req.head = head; this.handleClient(data, req); }; Manager.prototype.checkRequest = function (req) { var resource = this.get('resource'); console.log( 'req url:' + req.url ); var match; if (typeof resource === 'string') { match = req.url.substr(0, resource.length); if (match !== resource) match = null; } else { match = resource.exec(req.url); if (match) match = match[0]; } socket.io check the url if it's started with socket.io, like below (without nginx). note that all socket.io communication is gone with nginx. #### Socket.io debug without nginx req url:/ req url:/socket.io/socket.io.js debug - served static content /socket.io.js req url:/socket.io/1/?t=1359507255627 debug - client authorized info - handshake authorized tjAKZXz4h8Cv3EeK7xyq req url:/favicon.ico req url:/socket.io/1/websocket/tjAKZXz4h8Cv3EeK7xyq debug - setting request GET /socket.io/1/websocket/tjAKZXz4h8Cv3EeK7xyq #### Conclusions it appears normal websocket will work, but socket.io is looking for something which the setup doesn't provide. ### Disable destroy upgrade var app = require('express')() , server = require('http').createServer(app) , io = require('socket.io').listen(server); io.set("destroy upgrade",false); the page won't load. probably because that option only means socket.io won't destroy the connection but won't serve it either. ### Only do websocket upgrade for /socket.io location / { proxy_set_header X-Real-IP$remote_addr;
proxy_set_header Host $http_host; proxy_pass http://node; proxy_buffering off; } location /socket.io { chunked_transfer_encoding off; proxy_set_header X-Real-IP$remote_addr;
proxy_set_header Host $http_host; proxy_set_header Connection "Upgrade"; proxy_set_header Upgrade websocket; proxy_http_version 1.1; proxy_pass http://node; proxy_buffering off; proxy_redirect off; } #### socket.io debug log req url:/ req url:/socket.io/socket.io.js warn - unknown transport: "undefined" req url:/favicon.ico #### Socket.io - manager.js Manager.prototype.handleClient = function (data, req) { .... if (!~this.get('transports').indexOf(data.transport)) { this.log.warn('unknown transport: "' + data.transport + '"'); req.connection.end(); return; } looks like data is lost. ### Forth Attempt: Nginx 1.2.6 with TCP proxy module 1. # goto http://yaoweibin.github.com/nginx_tcp_proxy_module/ 2. # download tarball 3. # extract tarball 4. # cd nginx-1.2.6 5. # patch -p1 < ../yaoweibin-nginx_tcp_proxy_module-f1d5c62/tcp.patch patching file src/core/ngx_log.c Hunk #1 succeeded at 67 (offset 1 line). patching file src/core/ngx_log.h Hunk #1 succeeded at 30 (offset 1 line). Hunk #2 succeeded at 38 (offset 1 line). patching file src/event/ngx_event_connect.h Hunk #1 succeeded at 33 (offset 1 line). Hunk #2 succeeded at 44 (offset 1 line). 1. # ./configure --add-module=../yaoweibin-nginx_tcp_proxy_module-f1d5c62 --with-http_ssl_module 2. # make 3. # sudo make install #### Nginx.config tcp { upstream node { server 127.0.0.1:7010; server 127.0.0.1:7020; check interval=3000 rise=2 fall=5 timeout=1000; } server { listen 80; listen 443 ssl; server_name host; ssl_certificate /home/arthur/ssl/ssl.crt; ssl_certificate_key /home/arthur/ssl/privateKey.key; ssl_protocols SSLv3 TLSv1; ssl_ciphers HIGH:!aNULL:!MD5; tcp_nodelay on; proxy_pass node; } } http { ... server { listen 7000; location /websocket_status { check_status; } #### Socket.io debug log req url:/ req url:/socket.io/socket.io.js debug - served static content /socket.io.js req url:/socket.io/1/?t=1359508983909 debug - client authorized info - handshake authorized Ky0M5xgxULfhGesu85-D req url:/favicon.ico req url:/socket.io/1/websocket/Ky0M5xgxULfhGesu85-D debug - setting request GET /socket.io/1/websocket/Ky0M5xgxULfhGesu85-D debug - set heartbeat interval for client Ky0M5xgxULfhGesu85-D debug - client authorized for debug - websocket writing 1:: debug - websocket writing 5:::{"name":"news","args":[{"hello":"world"}]} { my: 'data' } debug - emitting heartbeat for client Ky0M5xgxULfhGesu85-D debug - websocket writing 2:: debug - set heartbeat timeout for client Ky0M5xgxULfhGesu85-D debug - got heartbeat packet debug - cleared heartbeat timeout for client Ky0M5xgxULfhGesu85-D debug - set heartbeat interval for client Ky0M5xgxULfhGesu85-D ### HTTPS https resulted with the same output. didn't fall back to XHR. ### Fail over browser conenct to one of the node.js in the upstream server. kill the node.js, the connection reconnected to the other node.js immediately. #### Socket.io debug output for node listening on port 7020$ node server 7020
info  - socket.io started
port 7020
debug - served static content /socket.io.js
debug - client authorized
info  - handshake authorized AvAMO0vBRo3BbzCBGntx
debug - setting request GET /socket.io/1/websocket/AvAMO0vBRo3BbzCBGntx
debug - set heartbeat interval for client AvAMO0vBRo3BbzCBGntx
debug - client authorized for
debug - websocket writing 1::
debug - websocket writing 5:::{"name":"news","args":[{"hello":"world"}]}
{ my: 'data' }
{code}

kill node 7020.

$node server 7010 info - socket.io started port 7010 debug - client authorized info - handshake authorized GpQU1HmA7Ei8bZt1GmSD debug - setting request GET /socket.io/1/websocket/GpQU1HmA7Ei8bZt1GmSD debug - set heartbeat interval for client GpQU1HmA7Ei8bZt1GmSD debug - client authorized for debug - websocket writing 1:: debug - websocket writing 5:::{"name":"news","args":[{"hello":"world"}]} { my: 'data' } note that the log for the first time connect & reconnect on the server side is exactly the same. it even execute the init code to send out the test events. ### Concerns: Splitting websocket & non-websocket traffic on the same port [http://www.exratione.com/2012/07/proxying-websocket-traffic-for-nodejs-the-present-state-of-play/] The TCP Proxy Module for Nginx Doesn't Solve the Problem The excellent nginx_tcp_proxy_module allows Nginx to be used as a proxy for websocket traffic, as outlined in a post from last year. Unfortunately it is really only intended for load balancing - you can't use it to split out websocket versus non-websocket traffic arriving on the same port and send them to different destinations based on URI. Additionally, this requires a custom build to include the module into Nginx - which might be an issue for future support and upgrades. so, if we want to serve static content from the same nginx too, it has to be on another port. i.e. you'll have to open up another port for the static content. ### Licensing Concern Not sure how valid the concern is, but Weibin mentioned that he borrowed code from Igor & Jack's work. https://github.com/yaoweibin/nginx_tcp_proxy_module Copyright & License This README template copy from agentzh (<http://github.com/agentzh>). I borrowed a lot of code from upstream and mail module from the nginx 0.7.* core. This part of code is copyrighted by Igor Sysoev. And the health check part is borrowed the design of Jack Lindamood's healthcheck module healthcheck_nginx_upstreams (<http://github.com/cep21/healthcheck_nginx_upstreams>); This module is licensed under the BSD license. Copyright (C) 2012 by Weibin Yao <yaoweibin@gmail.com>. All rights reserved. ## Monday, January 28, 2013 ### JBoss OSGi We have migrated to JBoss from Tomcat+Equinox recently. There's a challenge to do the migration basically the documenation in jboss is a bit less than desired. Here is the osgi subsystem in standalone.xml we finally use. <subsystem xmlns="urn:jboss:domain:osgi:1.2" activation="eager"> <properties> <property name="org.jboss.osgi.system.modules.extra"> org.apache.log4j, org.apache.commons.logging, org.slf4j, javax.xml.bind.api </property> <property name="org.osgi.framework.startlevel.beginning"> 5 </property> <property name="org.osgi.framework.system.packages.extra"> org.apache.log4j;version=1.2.15, org.apache.commons.logging;version=1.1.1, org.slf4j;version=1.6, javax.activation;version=1.1.1, javax.xml.bind;version=2.2, sun.security.provider;version=1.0 </property> </properties> <capabilities> <capability name="javax.servlet.api"/> <capability name="javax.transaction.api"/> <capability name="javax.xml.bind.api"/> <capability name="javax.api"/> <capability name="javax.enterprise.api"/> <capability name="org.apache.felix.log" startlevel="1"/> <capability name="org.apache.felix.configadmin" startlevel="1"/> <capability name="org.jboss.osgi.logging" startlevel="1"/> <capability name="org.jboss.logmanager"/> <capability name="javax.ws.rs.api" startlevel="1"/> <capability name="org.jboss.resteasy.resteasy-jaxrs" startlevel="3"/> <capability name="ch.qos.cal10n"/> <capability name="org.apache.commons.beanutils"/> <capability name="org.apache.commons.codec"/> <capability name="org.apache.commons.collections"/> <capability name="org.apache.commons.lang"/> <capability name="org.apache.commons.io"/> <capability name="org.codehaus.jackson.jackson-core-asl"/> <capability name="org.codehaus.jackson.jackson-jaxrs"/> <capability name="org.codehaus.jackson.jackson-mapper-asl"/> <capability name="org.codehaus.jackson.jackson-xc"/> </capabilities> </subsystem> The first thing we discovered is we have to use JBoss' logging. It's well integrated, easy to use, but if you tried to deploy your own slf4j, log4j... it just won't work. The 2nd thing is the org.jboss.osgi.system.modules.extra & org.osgi.framework.system.packages.extra, without them, some of the package are exported without version. And what you see here is a list of all that I can find on different blog posts or forum. Also, there're two version of javax.servlet.api, one being javax.servlet.api:v25 and the one i've used here is for servlet api 3.0 which is required by resteasy. We also use resteasy-jackson-provider, but the one in jboss module exported a package which "masks" the same package exported in resteasy-jaxrs. I've raised a JIRA about it. Meanwhile, i've repackaged the resteasy-jackson-provider so it won't export that package. At last, jboss also comes with a jboss config admin integration, which will add the configurations to the configadmin subsystem in standalone.xml. However, it doesn't support list as value (Apache Felix FileInstall supports that). Thus, if you are using FileInstall, you'll have to disable the jboss config admin (by not adding the capability to osgi subsystem) ## Sunday, January 27, 2013 ### How to add service properties to services created by Managed Service Factory When using managed-service-factory, The bean created will be registered as OSGi service having bean-name set to <factory id>.<uuid> which is of no use to tell the service apart. In this example, the configuration has a name property and we'd like to set the name to the cache instance so that it can be imported like this, <reference interface="org.sprintframework.cache.Cache" filter="(cacheName=abcde)"/> Gemini Blueprint 1.0.2 does allow <service-property> in the managed-service-factory, but it appears it only support simple value, not programatically. To do that, we need to get the ServiceRegistration for the service (which is returned when a service is added to the registry) as that is the only way to update a service's properties. Luckily, the managed-service-factory bean will actually return a list of ServiceRegistration that it created. You can simply get the list of ServiceRegistration from the factory bean if you are sure the configuration is always set before you make the call to get the list but in our case, we use something like FileInstall which will add configuration automatically, we'll have to register a service listener and update the new service's property accordingly. Another issue is that the serviceChanged is actually called before the new ServiceRegistration is added to the list. thus, if we get the list of service registrations in the serviceChanged call, we will always miss the newly created one. The service properties dictionary returned (in JBoss) is a JBoss internal class which is immutable, so i have to create a new dictionary (didn't use the internal class to avoid dependency) and overwrite the internal implementation. Didn't test if JBoss will convert the hashtable to its internal implementation when I call setProperties but it seems to work fine. public class ManagedServicePropertyUpdater implements ApplicationContextAware, InitializingBean, ServiceListener { private OsgiBundleXmlApplicationContext osgiAppCtx; private BundleContext bundleContext; private BeanFactory beanFactory; @Getter @Setter private String serviceInterfaceClassName; @Getter @Setter private String managedServiceFactoryBeanName; @Getter @Setter private String servicePropertyKey; @Getter @Setter private String servicePropertyValueMethodName; @Override public void afterPropertiesSet() throws Exception { assert (serviceInterfaceClassName!=null); assert (managedServiceFactoryBeanName!=null); assert (servicePropertyKey!=null); assert (servicePropertyValueMethodName!=null); } @Override public void setApplicationContext(ApplicationContext applicationContext) throws BeansException { osgiAppCtx = (OsgiBundleXmlApplicationContext)applicationContext; bundleContext = osgiAppCtx.getBundleContext(); beanFactory = osgiAppCtx.getBeanFactory(); String filter = "(" + Constants.OBJECTCLASS + "=" + serviceInterfaceClassName + ")"; try { bundleContext.addServiceListener(this,filter); } catch( InvalidSyntaxException e ) { throw new BeanCreationException("fail registering service listener for Cache", e); } Collection serviceRegistrations = (Collection)beanFactory.getBean(managedServiceFactoryBeanName); for( Object sr : serviceRegistrations) { addServiceProperty((ServiceRegistration) sr); } } @Override public void serviceChanged(ServiceEvent event) { final ServiceReference reference = event.getServiceReference(); ExecutorService exec = Executors.newSingleThreadExecutor(); exec.submit( new Runnable() { @Override public void run() { ServiceRegistration registration = mustFindServiceRegistration(reference); addServiceProperty(registration); } }); exec.shutdown(); } private ServiceRegistration findServiceRegistration(ServiceReference reference) { Collection serviceRegistrations = (Collection)beanFactory.getBean(managedServiceFactoryBeanName); for( Object srObj : serviceRegistrations ) { ServiceRegistration sr = (ServiceRegistration) srObj; ServiceReference ref = sr.getReference(); if( ref.compareTo(reference) == 0 ){ return sr; } } return null; } private ServiceRegistration mustFindServiceRegistration(ServiceReference serviceReference) { ServiceRegistration serviceRegistration = null; int count = 0; do{ if( count > 0 ) { try { Thread.sleep(1000); } catch( InterruptedException e ){} } count ++; serviceRegistration = findServiceRegistration(serviceReference); } while( serviceRegistration == null && count < 10); if( serviceRegistration == null ) throw new IllegalArgumentException("cannot find service" ); return serviceRegistration; } private void addServiceProperty(ServiceRegistration sr) { try { ServiceReference ref = sr.getReference(); Object service = bundleContext.getService(ref); if( !(service instanceof Cache) ) { return; } Dictionary dict = OsgiServiceReferenceUtils.getServiceProperties(ref); if( dict.get(servicePropertyKey) == null ) { Dictionary newProps = new Hashtable(); Enumeration keys = dict.keys(); while( keys.hasMoreElements() ) { String key = keys.nextElement().toString(); newProps.put(key, dict.get(key) ); } Class serviceClass = service.getClass(); Method getMethod = serviceClass.getMethod(servicePropertyValueMethodName); String servicePropertyValue = (String)getMethod.invoke(service); newProps.put( servicePropertyKey, servicePropertyValue ); sr.setProperties(newProps); } bundleContext.ungetService(ref); } catch( Exception e ) { e.printStackTrace(); } } } ### Using Spring Security in OSGi without WAB This is actually inspired by another post that use Apache CXF in OSGi (but I couldn't find the link now). Apache CXF D-OSGi, you can add a propety to the OSGi service so that it will use the filter (ServletFilter) <osgi:service ref="searchRS" interface="...search.webservice.SearchWS"> <osgi:service-properties> <entry key="service.exported.interfaces" value="*" /> <entry key="service.exported.configs" value="org.apache.cxf.rs" /> <entry key="org.apache.cxf.rs.httpservice.context" value="/search" /> <entry key="org.apache.cxf.httpservice.requirefilter" value="true" /> <entry key="org.apache.cxf.rs.provider"> <array> <ref bean="jsonProvider" /> </array> </entry> </osgi:service-properties> </osgi:service> and <osgi:service ref="customFilterChain" interface="javax.servlet.Filter"> <osgi:service-properties> <entry key="org.apache.cxf.httpservice.filter" value="true" /> <entry key="servletNames" value="none" /> </osgi:service-properties> </osgi:service> With this, the customFilterChain will be used everytime when /search has been accessed. To setup the filter chain, <?xml version="1.0" encoding="UTF-8"?> <beans xmlns="http://www.springframework.org/schema/beans" xmlns:osgi="http://www.eclipse.org/gemini/blueprint/schema/blueprint" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:security="http://www.springframework.org/schema/security" xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd http://www.springframework.org/schema/security http://www.springframework.org/schema/security/spring-security.xsd http://www.eclipse.org/gemini/blueprint/schema/blueprint http://www.eclipse.org/gemini/blueprint/schema/blueprint/gemini-blueprint.xsd"> <bean id="customSecurityFilter" class="...security.filter.CustomSecurityFilter"/> <bean id="requestContextFilter" class="org.springframework.web.filter.RequestContextFilter"/> <!-- disable url rewrite, change session key --> <bean id="httpSessionSecurityContextRepository" class="org.springframework.security.web.context.HttpSessionSecurityContextRepository" /> <bean id="springSecurityFilter" class="org.springframework.security.web.context.SecurityContextPersistenceFilter" > <constructor-arg ref="httpSessionSecurityContextRepository" /> <property name="forceEagerSessionCreation" value="false" /> </bean> <bean id="basicAuthenticationFilter" class="org.springframework.security.web.authentication.www.BasicAuthenticationFilter" > <constructor-arg ref="customAuthenticationManager" /> </bean> <bean id="http403ForbiddenEntryPoint" class="org.springframework.security.web.authentication.Http403ForbiddenEntryPoint"/> <bean id="exceptionTranslationFilter" class="org.springframework.security.web.access.ExceptionTranslationFilter"> <constructor-arg ref="http403ForbiddenEntryPoint" /> <!-- can redirect to https here --> </bean> <bean id="sessionManagementFilter" class="org.springframework.security.web.session.SessionManagementFilter"> <constructor-arg ref="httpSessionSecurityContextRepository"/> <constructor-arg ref="sessionFixationProtectionStrategy" /> </bean> <bean id="sessionFixationProtectionStrategy" class="org.springframework.security.web.authentication.session.SessionFixationProtectionStrategy"> <property name="migrateSessionAttributes" value="true"/> </bean> <bean id="customFilterChain" class="org.springframework.security.web.FilterChainProxy"> <security:filter-chain-map request-matcher="ant"> <security:filter-chain pattern="/osgi/auth/**" filters="springSecurityFilter,requestContextFilter,basicAuthenticationFilter,sessionManagementFilter,exceptionTranslationFilter"/> <security:filter-chain pattern="/**" filters="springSecurityFilter,requestContextFilter,customSecurityFilter,exceptionTranslationFilter"/> </security:filter-chain-map> </bean> </beans> note that we have our own AuthenticationProvider and only /auth will perform Basic Authentication Filter. After we've migrated to Resteasy, we're still keeping the filter chain, and instead of registering to OSGi and let Apache CXF handles it, we registered to the WebContainer directly (see my other post about Resteasy & Pax Web). ### Resteasy & Gemini Blueprint (Springdm) & Pax Web inspired by sarbarian, I have created a gemini blueprint version which registered to pax web (in fact any other HTTP service will do) import webcontainer from pax web in osgi-context.xml. <?xml version="1.0" encoding="UTF-8"?> <blueprint xmlns="http://www.osgi.org/xmlns/blueprint/v1.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.osgi.org/xmlns/blueprint/v1.0.0 http://www.osgi.org/xmlns/blueprint/v1.0.0/blueprint.xsd"> <reference id="webContainer" interface="org.ops4j.pax.web.service.WebContainer" /> <reference id="customFilterChain" interface="javax.servlet.Filter"/> </blueprint> define reateasy server bean in module-context.xml. <beans xmlns="http://www.springframework.org/schema/beans" xmlns:osgi="http://www.eclipse.org/gemini/blueprint/schema/blueprint" xmlns:osgix="http://www.eclipse.org/gemini/blueprint/schema/blueprint-compendium" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:context="http://www.springframework.org/schema/context" xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd http://www.eclipse.org/gemini/blueprint/schema/blueprint http://www.eclipse.org/gemini/blueprint/schema/blueprint/gemini-blueprint.xsd http://www.eclipse.org/gemini/blueprint/schema/blueprint-compendium http://www.eclipse.org/gemini/blueprint/schema/blueprint-compendium/gemini-blueprint-compendium.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd"> <bean id="resteasy-server" class="...impl.ResteasyServiceImpl" init-method="init" destroy-method="cleanup"> <property name="webContainer" ref="webContainer"/> <property name="securityFilter" ref="customFilterChain" /> <property name="resteasyServlet" ref="resteasyServlet" /> <property name="resteasyBootstrap" ref="resteasyBootstrap" /> </bean> <bean id="resteasyServlet" class="...ResteasyServlet" /> <bean id="resteasyBootstrap" class="...servlet.ResteasyBootstrap" /> </beans> In the init method, register Resteasy as if you are doing that in the web.xml, which in our case, we don't have web.xml (we didn't use WAB) /* <listener> <listener-class>org.jboss.resteasy.plugins.server.servlet.ResteasyBootstrap</listener-class> </listener> <servlet> <servlet-name>Resteasy</servlet-name> <servlet-class>org.jboss.resteasy.plugins.server.servlet.HttpServletDispatcher</servlet-class> </servlet> <servlet-mapping> <ervlet-name>Resteasy</servlet-name> <url-pattern>/osgi/*</url-pattern> </servlet-mapping> <context-param> <param-name>resteasy.servlet.mapping.prefix</param-name> <param-value>/osgi</param-value> </context-param> <context-param> <param-name>resteasy.scan</param-name> <param-value>false</param-value> </context-param> */ private void init() { try { HttpContext httpContext = webContainer.getDefaultSharedHttpContext(); // context param must be set first to the http context Dictionary contextParam = new Hashtable(); contextParam.put("resteasy.servlet.mapping.prefix", "/osgi" ); contextParam.put("resteasy.scan", "false" ); webContainer.setContextParam(contextParam, httpContext); // add security filter webContainer.registerFilter(securityFilter,new String[]{"/osgi/*"}, new String[] {"customSecurityFilterChain"}, null, httpContext ); logger.info( "Security Filter has been registered to /osgi/*" ); // register resteasy bootstrap listener which would initialize resteasy framework // it will also add the registry to the servlet context webContainer.registerEventListener( resteasyBootstrap, httpContext ); // register resteasy dispatcher servlet webContainer.registerServlet( resteasyServlet, "Resteasy", new String[]{ "/osgi/*" }, null, httpContext ); servletContext = resteasyServlet.getServletConfig().getServletContext(); //ResteasyProviderFactory providerFactory = ResteasyProviderFactory.getInstance(); ResteasyProviderFactory providerFactory = (ResteasyProviderFactory) servletContext.getAttribute(ResteasyProviderFactory.class.getName()); ResteasyJacksonProvider jacksonProvider = new ResteasyJacksonProvider(); ObjectMapper objectMapper = jaxbUtils.getJsonMapper(); jacksonProvider.setMapper( objectMapper ); providerFactory.addBuiltInMessageBodyWriter(jacksonProvider); providerFactory.addBuiltInMessageBodyReader(jacksonProvider); try { ByteArrayProvider byteArrayProvider = new ByteArrayProvider(); providerFactory.addBuiltInMessageBodyWriter(byteArrayProvider); DefaultTextPlain defaultTextPlain = new DefaultTextPlain(); providerFactory.addBuiltInMessageBodyWriter(defaultTextPlain); StringTextStar stringTextStar = new StringTextStar(); providerFactory.addBuiltInMessageBodyWriter(stringTextStar); }catch( Throwable ignore ) { logger.debug( "defect in reasteasy-jackson-provider, should not export org.jboss.resteasy.plugins.providers"); } logger.info("RESTEasy Framework started on osgi"); /* register service listener to add JAX-RS annotated class to resteasy */ bundleContext.addServiceListener(this, serviceFilter); ServiceReference[] references = bundleContext.getServiceReferences( (String)null, serviceFilter); for(ServiceReference reference : references) { try { Object service = bundleContext.getService(reference); addResource(service); bundleContext.ungetService(reference); } catch ( Throwable ignore ) { logger.debug( "exception in adding jaxrs resource to resteasy" ); } } } catch (Throwable e) { logger.error("Error registering resteasy servlet", e); } } @Override public void serviceChanged(ServiceEvent event) { ServiceReference sr = event.getServiceReference(); switch(event.getType()) { case ServiceEvent.REGISTERED: try { addResource(bundleContext.getService(sr)); bundleContext.ungetService(sr); } catch (Exception e) { e.printStackTrace(); } break; case ServiceEvent.UNREGISTERING: try { removeResource(bundleContext.getService(sr)); bundleContext.ungetService(sr); } catch (Exception e) { e.printStackTrace(); } break; } } @Override public void addResource(Object resource) { if (resource != null ) { for( Class _interface : resource.getClass().getInterfaces() ){ if( _interface.isAnnotationPresent( Path.class ) ) { logger.info("Adding JAX-RS resource: " + resource.getClass().getName()); Registry resteasyRegistry = getRegistry(); if( resteasyRegistry != null ) resteasyRegistry.addSingletonResource(resource); logger.debug("resource " + resource.getClass().getName() + " added to resteasy"); break; } } } } @Override public void removeResource(Object resource) { if (resource != null && resource.getClass().isAnnotationPresent(Path.class)) { logger.info("Removing JAX-RS resource: " + resource.getClass().getName()); getRegistry().removeRegistrations(resource.getClass()); } } public Registry getRegistry() { if (servletContext != null) { return (Registry) servletContext.getAttribute(Registry.class.getName()); }else{ return null; } } Please note that you'll have to implement BundleContextAware to get the BundleContext and ServiceListener to listen to new services. at last, to clean up when the bundle is being unload (or refresh) private void cleanup() { try { webContainer.unregisterEventListener(resteasyBootstrap); }catch ( Exception ignored ) {} try { webContainer.unregisterServlet(resteasyServlet); }catch ( Exception ignored ) {} try { webContainer.unregisterFilter(securityFilter); }catch ( Exception ignored ) {} try { webContainer.getDefaultSharedHttpContext().deregisterBundle(bundleContext.getBundle()); }catch ( Exception ignored ) {} try { bundleContext.removeServiceListener(this); }catch ( Exception ignored ) {} } ### Wrapper bundle for non-OSGi packages All we need is add Bundle-ClassPath to the wrapper's manifest.mf and packaged it with dependency plugin. Below is an example of how to build a wrapper for Jedis. Manifest-Version: 1.0 Bundle-Version: 2.1.0 Bundle-ManifestVersion: 2 Bundle-Name: Jedis Wrapper Bundle-Description: Wrapper bundle for Jedis Import-Package: org.slf4j, org.apache.commons.pool.impl, org.apache.commons.pool Export-Package: redis.clients.jedis;version="2.1.0",redis.clients.util;version="2.1.0",redis.clients.jedis.exceptions;version="2.1.0" Bundle-SymbolicName: wrapper-jedis_bundle Bundle-ClassPath: .,jedis-2.1.0.jar <project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd"> <modelVersion>4.0.0</modelVersion> <groupId>redis.clients</groupId> <artifactId>wrapper-jedis</artifactId> <packaging>jar</packaging> <version>2.1.0</version> <name>wrapper-jedis</name> <url>http://maven.apache.org</url> <build> <plugins> <plugin> <groupId>org.apache.maven.plugins</groupId> <artifactId>maven-dependency-plugin</artifactId> <version>2.4</version> <executions> <execution> <id>copy-dependencies</id> <phase>prepare-package</phase> <goals> <goal>copy-dependencies</goal> </goals> <configuration> <includeArtifactIds>jedis</includeArtifactIds> <outputDirectory>${project.build.directory}/classes</outputDirectory>
<overWriteReleases>false</overWriteReleases>
<overWriteSnapshots>false</overWriteSnapshots>
</configuration>
</execution>
</executions>
</plugin>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-jar-plugin</artifactId>
<configuration>
<archive>
<manifestFile>src/main/resources/META-INF/MANIFEST.MF</manifestFile>
</archive>
</configuration>
</plugin>
</plugins>
</build>
<dependencies>
<dependency>
<groupId>redis.clients</groupId>
<artifactId>jedis</artifactId>
<version>2.1.0</version>
</dependency>
<dependency>
<groupId>commons-pool</groupId>
<artifactId>commons-pool</artifactId>
<version>1.5</version>
</dependency>
</dependencies>
</project>

Granted, the package exported or imported is a bit trail-and-error.  don't know if there's any good tools that can look into the bytecode of a jar file and generate the manifest file.  maybe bnd can, but haven't try that.

One of the difficulty when using OSGi is that if there are more than one version (or copies) of the same class available in different bundle, it is often difficult to tell what went wrong.

java.lang.LinkageError: loader constraint violation in interface itable initialization: when resolving method "org.eclipse.jetty.server.Request.getServletContext()Ljavax/servlet/ServletContext;" the class loader (instance of org/jboss/osgi/framework/internal/HostBundleClassLoader) of the current class, org/eclipse/jetty/server/Request, and the class loader (instance of org/jboss/modules/ModuleClassLoader) for interface javax/servlet/ServletRequest have different Class objects for the type javax/servlet/ServletContext used in the signature
22:44:51,428 ERROR [stderr] (qtp1026914784-119 Selector0)     at org.eclipse.jetty.server.AbstractHttpConnection.<init>(AbstractHttpConnection.java:151)

org.springframework.aop.AopInvocationException: AOP configuration seems to be invalid: tried calling method [public abstract void org.ops4j.pax.web.service.WebContainer.registerServlet(javax.servlet.Servlet,java.lang.String,java.lang.String[],java.util.Dictionary,org.osgi.service.http.HttpContext) throws javax.servlet.ServletException] on target [org.ops4j.pax.web.service.internal.HttpServiceProxy@28a2f76f]; nested exception is java.lang.IllegalArgumentException: argument type mismatch
at org.springframework.aop.support.AopUtils.invokeJoinpointUsingReflection(AopUtils.java:326)

These are two of the error I got recently because there are actually two copies of ServletContext.  The first exception happens when I tried to call the rest interface (resteasy with pax web jetty bundle), the framework threw a LinkageError which has a very good error message showing both are loaded with a different classloader.  The 2nd error is when my code tried to register a servlet (which get the ServletContext from HostBundleClassLoader) to resteasy (which gets it from ModuleClassLoader).

I've developed a little code to print out more details about where the class is loaded.
private Map<String,Map<String,Object>> findClass(BundleContext context, String name) {
Map<String,Map<String,Object>> result = new HashMap<String,Map<String,Object>>();
for (Bundle b : context.getBundles()) {
try {
Class<?> c = b.loadClass(name);
Dictionary<String,String> dict = b.getHeaders();
Map<String,Object> value = new HashMap<String, Object>();
Enumeration<String> keys = dict.keys();
while( keys.hasMoreElements() ) {
String key = keys.nextElement();
value.put(key,dict.get(key));
}
value.put("class", c );
result.put(b.getSymbolicName() + " " + c, value );
} catch (ClassNotFoundException e) {
// No problem, this bundle doesn't have the class
} catch (Exception e) {
e.printStackTrace();
}
}
return result;
}

The idea is simple.  For each bundle, call findClass (which use the classloader of the bundle) and if it's found, get the headers, class loader & the location of the class itself and put everything in a hashmap.

Note that it's running on JBoss, the header dictionary it returned is unmutable.

Turns out the problem is because "bundles" from jboss' module directory (/standalone/modules) are loaded by ModuleClassLoader.

<subsystem xmlns="urn:jboss:domain:osgi:1.2" activation="eager">
...
<capabilities>
<capability name="org.jboss.resteasy.resteasy-jaxrs"/>
...

and it will automatically loaded all dependencies defined in path\to\jboss\modules\org\jboss\resteasy\resteasy-jaxrs\main\module.xml which includes javax.servlet.api.

However, unless you specifically declares that as one of the capabilities
<capability name="javax.servlet.api"/>
it won't be available to OSGi.  Adding the javax.servlet.api to jboss' osgi capabilities does completely solve the classloading issue as another copy of ServletContext is available in the pax web jetty bundle.  Since both are exporting javax.servlet;version=3.0.0, we have an intermitten LinkageError problem.

Two options here:

1. do not use the resteasy in the jboss modules.  instead deploy it with the rest of the bundles so it won't load the servlet api with the module classloader.  thus, only the one loaded from pax web jetty bundle will be used.  Because resteasy in the central maven repo is not osgi ready, i'll have to wrap it in a bundle.
2.  instead of using pax web jetty bundle, use the individual pax web jetty, pax web runtime...  I did a simple test, looks like pax web runtime (2.1.2) has problem importing the javax.servlet;version=3.0.0 from jboss.

not sure which options is better, i'll update the post once i'm done with it.