Rafael Sanches

June 20, 2012

Hazelcast + Spring + @Cacheable

Filed under: java, performance, programming, server-side, spring — mufumbo @ 2:12 am

Today I’ve integrated Hazelcast with the @Cacheable spring annotation. I’ve chosen Hazelcast over EhCache + Terracotta, because it has a simpler configuration and there’s no need to run another deamon, which facilitates dev-environment setup.

Here is my hazelcast spring configuration, that is included in my main spring configuration:

<?xmlversion="1.0"encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:p="http://www.springframework.org/schema/p"
    xmlns:context="http://www.springframework.org/schema/context"
    xmlns:hz="http://www.hazelcast.com/schema/spring"
        xmlns:cache="http://www.springframework.org/schema/cache"
    xsi:schemaLocation="http://www.springframework.org/schema/beanshttp://www.springframework.org/schema/beans/spring-beans-3.1.xsd
 http://www.hazelcast.com/schema/springhttp://www.hazelcast.com/schema/spring/hazelcast-spring-2.1.xsd
 http://www.springframework.org/schema/contexthttp://www.springframework.org/schema/context/spring-context-3.1.xsd
 http://www.springframework.org/schema/cachehttp://www.springframework.org/schema/cache/spring-cache-3.1.xsd
 "> 
    <cache:annotation-driven cache-manager="cacheManager" mode="proxy" proxy-target-class="true" />

    <bean
        class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer"
        p:systemPropertiesModeName="SYSTEM_PROPERTIES_MODE_OVERRIDE">
        <property name="locations">
            <list>
                <value>classpath:/hazelcast-default.properties</value>
            </list>
        </property>
    </bean>

    <hz:hazelcast id="instance">
        <hz:config>
            <hz:group name="mygroup" password="mypassword" />
            <hz:network port="5700" port-auto-increment="false">
                <hz:join>
                    <hz:multicast enabled="true" />
                    <hz:tcp-ip enabled="true">
                        <hz:interface>127.0.0.1:5700</hz:interface>
                    </hz:tcp-ip>
                </hz:join>
                <hz:interfaces enabled="true">
                    <hz:interface>127.0.0.1</hz:interface>
                </hz:interfaces>
            </hz:network>

            <hz:map name="default">
                <hz:map-store enabled="true" write-delay-seconds="0"
                    class-name="com.mufumbo.server.cache.hazelcast.EmptyCacheMapLoader" />
            </hz:map>

            <hz:map name="null-map" />

            <hz:map name="app" backup-count="3" async-backup-count="1"
                time-to-live-seconds="10" max-size="100" eviction-percentage="50"
                cache-value="true" eviction-policy="LRU" merge-policy="hz.LATEST_UPDATE" />
        </hz:config>
    </hz:hazelcast>

    <hz:config id="liteConfig">
        <hz:lite-member>true</hz:lite-member>
    </hz:config>

    <!-- set hazelcast spring cache manager -->  
    <bean id="cacheManager" class="com.hazelcast.spring.cache.HazelcastCacheManager">
        <constructor-arg ref="instance" />
    </bean>
</beans>

Please, notice the mode=”proxy” proxy-target-class=”true”. Without that configuration the beans with a super constructor and @Cacheable haven’t loaded. Notice that this isn’t a Hazelcast issue, it’s a Spring AOP issue, even if you use the SimpleCacheManager instead of Hazelcast one.

I was wondering about using mode=”aspectj”, but it was taking too much time, so maybe another day.

ATTENTION: CGLib proxies requires that the class needs to provide a default constructor, i.e. without any arguments. Otherwise you’ll get an IllegalArgumentException: “Superclass has no null constructors but no arguments were given.” This makes constructor injection impossible.

ATTENTION 2: Be careful if you have a BeanNameAutoProxyCreator matching the class that you flag as @Cacheable. In that case it means that there’s already an Cglib proxy behind, which can’t happen. It’s a hassle because I was using a BeanNameAutoProxyCreator to match all my *Service classes in order to create the JDO transactions on the methods create*, update* and save*. If you had the same problem, replace all your BeanNameAutoProxyCreator configuration with an AOP configuration like:

<tx:annotation-driven transaction-manager="transactionManager" mode="proxy" proxy-target-class="true" />

    <aop:config>
        <!-- http://blog.espenberntsen.net/tag/pointcut/ -->
        <!-- For all the classes annotated with @Service -->
        <aop:pointcut id="serviceMethodsCut" expression="within(@org.springframework.stereotype.Service *)" /> 
        <aop:advisor advice-ref="txAdvice" pointcut-ref="serviceMethodsCut" />
    </aop:config>

    <aop:config>
        <!-- For all the methods annotated with @Transactional -->
        <aop:pointcut id="transactionalCut" expression="execution(@org.springframework.transaction.annotation.Transactional * *(..))" />
        <aop:advisor advice-ref="txAdvice" pointcut-ref="transactionalCut" />
    </aop:config>

    <tx:advice id="txAdvice" transaction-manager="transactionManager">
        <tx:attributes>
            <tx:method name="update*" propagation="REQUIRES_NEW" rollback-for="java.lang.Exception"/>
            <tx:method name="insert*" propagation="REQUIRES_NEW" rollback-for="java.lang.Exception"/>
            <tx:method name="create*" propagation="REQUIRES_NEW" rollback-for="java.lang.Exception"/>
            <tx:method name="delete*" propagation="REQUIRES_NEW" rollback-for="java.lang.Exception"/>
            <tx:method name="save*" propagation="REQUIRES_NEW" rollback-for="java.lang.Exception"/>
            <tx:method name="store*" propagation="REQUIRES_NEW" rollback-for="java.lang.Exception"/>
            <tx:method name="get*" propagation="REQUIRED" read-only="true" />
            <tx:method name="*" propagation="SUPPORTS" read-only="true" />
        </tx:attributes>
    </tx:advice>

 

Also, remember to update your pom.xml with the AspectJ configuration:

<dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-aspects</artifactId>
            <version>${org.springframework-version}</version>
        </dependency>

        <dependency>
            <groupId>aspectj</groupId>
            <artifactId>aspectjrt</artifactId>
            <version>1.5.4</version>
        </dependency>

        <dependency>
           <groupId>org.aspectj</groupId>
           <artifactId>aspectjweaver</artifactId>
           <version>1.6.12</version>
        </dependency>

            <plugin>
                <groupId>org.codehaus.mojo</groupId>
                <artifactId>aspectj-maven-plugin</artifactId>
                <version>1.4</version>
                <configuration>
                    <Xlint>warning</Xlint>
                    <complianceLevel>1.7</complianceLevel>
                    <source>1.7</source>
                    <target>1.7</target>
                    <encoding>UTF-8</encoding>
                    <aspectLibraries>
                        <aspectLibrary>
                            <groupId>org.springframework</groupId>
                            <artifactId>spring-aspects</artifactId>
                        </aspectLibrary>
                    </aspectLibraries>
                </configuration>
                <executions>
                    <execution>
                        <goals>
                            <goal>compile</goal>
                            <goal>test-compile</goal>
                        </goals>
                    </execution>
                </executions>
            </plugin>

February 2, 2012

Spring-mvc + Velocity + DCEVM

Filed under: java, performance, server-side, spring, tutorial — mufumbo @ 5:54 pm

Java web development can be frustrating at times. Things that slow me down:

  • Excessive pre-configuration to be able to deliver results
  • Many people use JSP’s in a confusing way and end up with mixed patterns in the views.
  • Server restarts and deployment kill my productivity.

In order to improve dev speed I have been using these three technologies together:

  • Spring-MVC: This one makes it easier to bind controllers and views together, simply using annotations. This makes it very easy to create well defined controllers before the execution of the view.
  • Velocity: One of the most simple and powerful template engine available. With this I can define clear and simple templates that can access and interact with Java objects at the runtime.
  • DCEVM: Dynamic Code Evolution VM. A modification of the Java HotSpot(TM) VM that allows unlimited class redefinition at runtime. In our case it will enable to deploy changes in java classes without restarting the servlet container.

Since there are many tutorials on how to use these technologies singularly, this post will only cover how to bind these three technologies together. I would also suggest the usage of Maven to glue the dependencies together.

Lately many people are excited about the Play Framework which adds speed to Java development. Personally, I don’t like being too tight to a framework, but it seems very good.

I would recommend veloeclipse eclipse plugin for coloring the templates.

Glueing Velocity With Spring

There are many tutorials covering this part, like this one from velocity and this one from spring, but no one of them talks about WebappResourceLoader and how to use relative paths in the velocity templates and in the controllers.

Here’s the spring configuration that I use:

    <bean id="viewResolver"
        class="org.springframework.web.servlet.view.velocity.VelocityViewResolver">
        <property name="cache" value="true" />
        <property name="prefix" value="" />
        <property name="suffix" value=".vm" />
        <property name="toolboxConfigLocation" value="/WEB-INF/velocity/tools.xml" />
        <property name="exposeRequestAttributes" value="true"/>
        <property name="exposeSessionAttributes" value="true"/>
        <property name="exposeSpringMacroHelpers" value="true"/>

        <property name="attributesMap">
            <map>
                <entry key="dateTool"><bean class="org.apache.velocity.tools.generic.DateTool" /></entry>
                <entry key="escapeTool"><bean class="org.apache.velocity.tools.generic.EscapeTool" /></entry>
            </map>
        </property>
    </bean>

    <bean id="velocityConfig"
        class="org.springframework.web.servlet.view.velocity.VelocityConfigurer">
        <property name="configLocation" value="/WEB-INF/velocity/velocity.properties" />
        <property name="resourceLoaderPath">
            <value>/</value>
        </property>
        <property name="velocityProperties">
           <props>
                 <prop key="contentType">text/html;charset=UTF-8</prop>
           </props>
          </property>
    </bean>

It’s very important to use  org.apache.velocity.tools.view.WebappResourceLoader in order to facilitate development.

Using ClasspathResourceLoader makes development painful because depending on your configuration it won’t reload the templates when you’re changing, or sometimes it will refresh the entire webapp context in order to refresh a single template. This process can take you minutes after each template change.

Here’s my configuration for velocity.properties:

runtime.log.invalid.reference = true
runtime.log.logsystem.class=org.apache.velocity.runtime.log.CommonsLogLogChute

input.encoding=UTF-8
output.encoding=UTF-8

directive.include.output.errormsg.start = 

directive.parse.max.depth = 10

velocimacro.library.autoreload = true
velocimacro.library = /VM_global_library.vm
velocimacro.permissions.allow.inline = true
velocimacro.permissions.allow.inline.to.replace.global = false
velocimacro.permissions.allow.inline.local.scope = false

velocimacro.context.localscope = false

runtime.interpolate.string.literals = true

resource.manager.class = org.apache.velocity.runtime.resource.ResourceManagerImpl
resource.manager.cache.class = org.apache.velocity.runtime.resource.ResourceCacheImpl

resource.loader = webapp, class

class.resource.loader.description = Velocity Classpath Resource Loader
class.resource.loader.class = org.apache.velocity.runtime.resource.loader.ClasspathResourceLoader 

webapp.resource.loader.class = org.apache.velocity.tools.view.WebappResourceLoader
webapp.resource.loader.path = /WEB-INF/views/
webapp.resource.loader.cache = true
webapp.resource.loader.modificationCheckInterval = 2

Now you can start writing a simple java controller:

@Controller
public class MyControllerClass {
    @RequestMapping(value = "/my-url-path/{myPathVariable}", method = RequestMethod.GET)
    public String processRequest(@PathVariable String myPathVariable, @RequestParam(required = false) Long editId, Model model) {
        model.addAttribute("world", "world");
        return "/pages/forum/admin/forum-create";
    }
}

Now you can create simple velocity view with a templates like:

#parse("/parts/header.vm")

#parse("/parts/left-menu-p.vm")

Hello ${world}.

#parse("/parts/footer.vm")

Notice that no XML configuration was necessary, just the creation of the view and the controller. Also, thanks to DCEVM, there’s no need to restart the webapp after creating a new controller.

After configuring spring-mvc + velocity, the most important part is to configure DCEVM in order to not need to restart our tomcat container after every change in the classpath.

Configuring DCEVM

First download the binary from http://ssw.jku.at/dcevm/binaries/

If you’re in a windows or linux environment, just open the jar and choose the JDK that you want to have the modified VM running. Notice that you can enable and disable DCEVM support for that JDK. On Linux only the 32-bit JDK is supported.

If you’re running MacOSX you’ll have to download the 32-bit version of the Soylatte VM. This is available here: http://landonf.bikemonkey.org/static/soylatte/bsd-dist/javasrc_1_6_jrl_darwin/soylatte16-i386-1.0.3.tar.bz2

Unzip the soylatte VM under /Library/Java/JavaVirtualMachines/soylatte16-i386-1.0.3/

Now just run the dcevm-0.2.jar and choose /Library/Java/JavaVirtualMachines/soylatte16-i386-1.0.3/

After setting up the new VM we need to setup the eclipse project.

  1. Select the project properties and use the new JRE.
  2. Download tomcat and create a new server in eclipse, choose tomcat.
  3. Make it sure that your tomcat run in your newly created JRE.
  4. Open the new server configuration and make it sure to check “Automatically publish when resources change”
  5. Go to the server “modules” tab and edit your project web modules. Disable “Auto Reload”. This is extremely important since it will save you hours and days of restarting time.
  6. Just run your tomcat and every time you make a change on your project it will be pushed to the server. No need to restart!

For a more compreensive tutorial about how to configure tomcat + eclipse, please visit: How to Set Up Hot Code Replacement with Tomcat and Eclipse

If you like the DCEVM idea, also take a look into jRebel, which is even more powerful.

Also, if you use the Datanucleus JDO database, don’t forget to install the JDO eclipse plugin, in this way your classes are compiled on the fly after changes, so no need to restarts for enhancement.

Configuring Run-Jetty-Run Eclipse Plugin

Another simpler way is to install the Run Jetty Run plugin and run it over the new soylatte jvm. When creating your debug profile, remember to click in the JRE tab and choose the Soylatte VM. Running a jetty container with this plugin is 20 times faster than making a “mvn jetty:run”.

Install the plugin from their update site: http://run-jetty-run.googlecode.com/svn/trunk/updatesite

After the plugin is installed, remember to enable build automatically and disable source scanner in the jetty plugin:

run-jetty-run dcevm velocity

This will make it possible to save your java files and velocity templates without restarting the server. One cool configuration that I’ve made on mine is that I added the spring and velocity configuration directories to the “Custom Scan Folder and Files”, so every time I change any files it will redeploy the webapp. Notice that redeploying the webapp with this plugin is 20 times faster than making a “mvn jetty:run” from scratch.

June 13, 2011

Google Analytics lags on Android. How to make it more responsive!

Filed under: analytics, android, maintainability, performance — Tags: , , , — mufumbo @ 5:55 am

Google Analytics can be your best friend in order to track your mobile user behavior. Unfortunately the current Android implementation has performance limitations and the most problematic is that it uses SQLite to store your events.

Everyone who wants to write a responsive app knows that you can’t do SQLite operations in the UI Thread. Having to wrap the Google Analytics calls into a separated thread can be painful, so I wrote a very simple helper to handle it inside threads. I have many tracking events inside “button click” and it was taking about 200ms to execute, it’s too much on the UI Thread. It’s also too much if you have “onCreate” because it will take long time to open your new activity.

This helper is also very wrong because it maintains a static reference to the context. I do this in order to have better numbers on visit and “time on site”. You can just remove the static reference if you don’t like that.

Notice that my implementation has this: “Thread.sleep(3000);”
It means that I don’t want repetitive Google Analytics SQLite to be competing with my app inserts or gets.

This LAG happens because SQLite uses the internal memory which can be very slow depending on many factors, including concurrent SQLite operations or just internal memory without many space.

I hope it helps someone. Here’s the complete code:

package com.mufumbo.android.helper;

import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

import android.content.Context;
import android.util.Log;

import com.google.android.apps.analytics.GoogleAnalyticsTracker;

public class GAHelper {
    String activity;
    static GoogleAnalyticsTracker tracker;
    static int instanceCount = 0;
    long start;

    // Limit the number of events due to outofmemory exceptions of analytics sdk
    final static int MAX_EVENTS_BEFORE_DISPATCH = 200;
    static int eventCount = 0;

    static final ExecutorService tpe = Executors.newSingleThreadExecutor();

    public GAHelper(final Context c, final String activity) {
        this.activity = activity;
        instanceCount++;
        if (tracker == null) {
            tpe.submit(new Runnable() {
                @Override
                public void run() {
                    tracker = GoogleAnalyticsTracker.getInstance();
                    tracker.start(Constants.GOOGLE_ANALYTICS_ID, Constants.GOOGLE_ANALYTICS_DELAY, c.getApplicationContext());
                }
            });
        }
    }

    public void onResume() {
        this.trackPageView("/"+this.activity);
    }

    public synchronized void destroy () {
        instanceCount--;
        if (instanceCount <= 0) {
            tpe.submit(new Runnable() {
                @Override
                public void run() {
                    Log.i(Constants.TAG, "destroying GA");
                    if (tracker != null)
                        tracker.stop();
                    instanceCount = 0;
                }
            });
        }
    }

    protected void tick() throws InterruptedException {
        Thread.sleep(3000);
        this.start = System.currentTimeMillis();
    }

    public void log (final String l) {
        if (Dbg.IS_DEBUG) {
            Dbg.debug("['"+(System.currentTimeMillis()-start)+"']["+eventCount+"] Logging on '"+this.activity+"': "+l);
            if (l.contains(" ")) {
                Log.e(Constants.TAG, "DO NOT TRACK WITH SPACES: "+l, new Exception());
            }
        }

    }

    public void trackClick(final String button) {
        checkDispatch();
        tpe.submit(new Runnable() {
            @Override
            public void run() {
                try {
                    tick();
                    tracker.trackEvent(
                            "clicks",  // Category
                            activity+"-button",  // Action
                            button, // Label
                            1);
                    log("trackClick:"+button);
                } catch (final Exception e) {
                    Log.e(Constants.TAG, "Error tracking", e);
                }
            }
        });
    }

    public void trackEvent (final String category, final String action, final String label, final int count) {
        checkDispatch();
        tpe.submit(new Runnable() {
            @Override
            public void run() {
                try {
                    tick();
                    tracker.trackEvent(
                            category,  // Category
                            action,  // Action
                            activity+"-"+label, // Label
                            1);
                    log("trackEvent:"+category + "#"+action+"#"+label+"#"+count);
                } catch (final Exception e) {
                    Log.e(Constants.TAG, "Error tracking", e);
                }
            }
        });
    }

    public void trackPopupView (final String popup) {
        checkDispatch();
        tpe.submit(new Runnable() {
            @Override
            public void run() {
                try {
                    tick();
                    final String page = "/"+activity+"/"+popup;
                    tracker.trackPageView(page);
                    log("trackPageView:"+page);
                } catch (final Exception e) {
                    Log.e(Constants.TAG, "Error tracking", e);
                }
            }
        });
    }

    public void trackPageView (final String page) {
        checkDispatch();
        tpe.submit(new Runnable() {
            @Override
            public void run() {
                try {
                    tick();
                    tracker.trackPageView(page);
                    log("trackPageView:"+page);
                } catch (final Exception e) {
                    Log.e(Constants.TAG, "Error tracking", e);
                }
            }
        });
    }

    public void checkDispatch() {
        eventCount++;
        if (eventCount >= MAX_EVENTS_BEFORE_DISPATCH)
            dispatch();
    }

    public void dispatch(){
        eventCount = 0;
        tpe.submit(new Runnable() {
            @Override
            public void run() {
                try {
                    tick();
                    tracker.dispatch();
                    log("dispatched");
                } catch (final Exception e) {
                    Log.e(Constants.TAG, "Error dispatching", e);
                }
            }
        });
    }
}

January 30, 2011

HTC sense ui breaks the way the WebView settings behave

Filed under: android — mufumbo @ 11:32 pm

I am “amused” to discover that HTC sense has changed even the way android breaks to access of a WebView from outside the UI thread.

Since I don’t own a phone with HTC sense, it took me months to understand this and I only fixed the issue thanks to a kind user who sent me logs.

For example, calling this outside from a UI thread works on the normal android SDK’s:
webSettingsObj.setBuiltInZoomControls(true);

Instead, on HTC Sense phones it breaks here:

java.lang.RuntimeException: Can't create handler inside thread that has not called Looper.prepare()
 at android.os.Handler.(Handler.java:121)
 at com.htc.multitouch.MultiTouchDetector$MultiTouchHandler.(MultiTouchDetector.java:180)
 at com.htc.multitouch.MultiTouchDetector.(MultiTouchDetector.java:242)
 at android.webkit.WebView$HTCMultiTouch.fnCreateMultiTouchListener(WebView.java:11781)
 at android.webkit.WebView.enableMultiTouch(WebView.java:10893)
 at android.webkit.WebView.updateMultiTouchSupport(WebView.java:905)
 at android.webkit.WebSettings.setBuiltInZoomControls(WebSettings.java:474)

Now, I know know that anything that changes the UI shouldn’t be executed outside of the UI Thread, but still..

January 29, 2011

upload using multipart post using httpclient in android

Filed under: android — mufumbo @ 7:01 pm

A very common caveat, when doing android applications, is fighting to keep the APK size small.

Many applications need the ability to upload binary data to their server and when you arrive there you see that the android SDK doesn’t have the http-client libraries to send multipart posts.

The easiest way is to include the JAR for httpmime and apache_mime4j, but it takes way too much space; 300kb.

To overcome this you can implement your own HttpEntity. In this way the code is:

public class SimpleMultipartEntity implements HttpEntity {

    private final static char[] MULTIPART_CHARS = "-_1234567890abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ"
        .toCharArray();

    private String boundary = null;

    ByteArrayOutputStream out = new ByteArrayOutputStream();
    boolean isSetLast = false;
    boolean isSetFirst = false;

    public SimpleMultipartEntity() {
        final StringBuffer buf = new StringBuffer();
        final Random rand = new Random();
        for (int i = 0; i &lt; 30; i++) {
            buf.append(MULTIPART_CHARS[rand.nextInt(MULTIPART_CHARS.length)]);
        }
        this.boundary = buf.toString();

    }

    public void writeFirstBoundaryIfNeeds(){
        if(!isSetFirst){
            try {
                out.write(("--" + boundary + "\r\n").getBytes());
            } catch (final IOException e) {
                Log.e(Constants.TAG, e.getMessage(), e);
            }
        }
        isSetFirst = true;
    }

    public void writeLastBoundaryIfNeeds() {
        if(isSetLast){
            return ;
        }
        try {
            out.write(("\r\n--" + boundary + "--\r\n").getBytes());
        } catch (final IOException e) {
            Log.e(Constants.TAG, e.getMessage(), e);
        }
        isSetLast = true;
    }

    public void addPart(final String key, final String value) {
        writeFirstBoundaryIfNeeds();
        try {
            out.write(("Content-Disposition: form-data; name=\"" +key+"\"\r\n").getBytes());
            out.write("Content-Type: text/plain; charset=UTF-8\r\n".getBytes());
            out.write("Content-Transfer-Encoding: 8bit\r\n\r\n".getBytes());
            out.write(value.getBytes());
            out.write(("\r\n--" + boundary + "\r\n").getBytes());
        } catch (final IOException e) {
            Log.e(Constants.TAG, e.getMessage(), e);
        }
    }

    public void addPart(final String key, final String fileName, final InputStream fin){
        addPart(key, fileName, fin, "application/octet-stream");
    }

    public void addPart(final String key, final String fileName, final InputStream fin, String type){
        writeFirstBoundaryIfNeeds();
        try {
            type = "Content-Type: "+type+"\r\n";
            out.write(("Content-Disposition: form-data; name=\""+ key+"\"; filename=\"" + fileName + "\"\r\n").getBytes());
            out.write(type.getBytes());
            out.write("Content-Transfer-Encoding: binary\r\n\r\n".getBytes());

            final byte[] tmp = new byte[4096];
            int l = 0;
            while ((l = fin.read(tmp)) != -1) {
                out.write(tmp, 0, l);
            }
            out.flush();
        } catch (final IOException e) {
            Log.e(Constants.TAG, e.getMessage(), e);
        } finally {
            try {
                fin.close();
            } catch (final IOException e) {
                Log.e(Constants.TAG, e.getMessage(), e);
            }
        }
    }

    public void addPart(final String key, final File value) {
        try {
            addPart(key, value.getName(), new FileInputStream(value));
        } catch (final FileNotFoundException e) {
            Log.e(Constants.TAG, e.getMessage(), e);
        }
    }

    @Override
    public long getContentLength() {
        writeLastBoundaryIfNeeds();
        return out.toByteArray().length;
    }

    @Override
    public Header getContentType() {
        return new BasicHeader("Content-Type", "multipart/form-data; boundary=" + boundary);
    }

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

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

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

    @Override
    public void writeTo(final OutputStream outstream) throws IOException {
        outstream.write(out.toByteArray());
    }

    @Override
    public Header getContentEncoding() {
        return null;
    }

    @Override
    public void consumeContent() throws IOException,
    UnsupportedOperationException {
        if (isStreaming()) {
            throw new UnsupportedOperationException(
            "Streaming entity does not implement #consumeContent()");
        }
    }

    @Override
    public InputStream getContent() throws IOException,
    UnsupportedOperationException {
        return new ByteArrayInputStream(out.toByteArray());
    }

}

January 13, 2011

server-side calls are better for Ad serving. Downside of AFMA/AdMob.

Filed under: android, programming, revenue, technology — mufumbo @ 7:47 pm

Ad networks that offer server-side calls gives us a big advantage. We can simply get a image + link and print on a android WebView.

Due to limitations of the android framework it’s the only way to have non-intrusive ads inside a WebView. Specially when the WebView must be layout_height=”fill_parent”, for a correct scrolling and zoom control.

JavaScript ads are not an option, since the only work around is to inject JavaScript into the WebView which prevents me from working with JavaScript ads that are based on a inline include.

Advantages of the server-side call instead of SDK:
Reduce APK size: I can implement my own WebView to print ads. AdMob SDK takes 140kb, Google AFMA takes 40kb, so 30% of my app is taken from ads sdk’s.
– AFMA SDK is slow: rendering the adsense javascript is slow. I feel my app freezing and coming back after rendering adsense. Admob is much faster.
– The developer have total control to optimize it.

FYI: After the death of Quattro, the best network that is offering server-side calls is Millenial Media.

June 18, 2010

Using native twitter app Intent to share on android

Filed under: android — mufumbo @ 6:36 pm

I have been googling to find the Twitter native app intent that enables to share through it directly, but I couldn’t find any.

ATTENTION: This is just a hack. It’s better to just open the android popup with the Intent.ACTION_SEND intent.

I didn’t had time to test other ways, but the only way to launch the twitter PostActivity directly was to get the ActivityInfo instance of it. Please, give me feedback if you know a better way.

What this code does is to query all activities that match with the Intent.ACTION_SEND and then it searches for the “com.twitter.android.PostActivity” intent.

try{
    intent = new Intent(Intent.ACTION_SEND);
    intent.putExtra(Intent.EXTRA_TEXT, message);
    intent.setType("text/plain");
    final PackageManager pm = context.getPackageManager();
    final List activityList = pm.queryIntentActivities(intent, 0);
        int len =  activityList.size();
    for (int i = 0; i < len; i++) {
        final ResolveInfo app = activityList.get(i);
        if ("com.twitter.android.PostActivity".equals(app.activityInfo.name)) {
            final ActivityInfo activity=app.activityInfo;
            final ComponentName name=new ComponentName(activity.applicationInfo.packageName, activity.name);
            intent=new Intent(Intent.ACTION_SEND);
            intent.addCategory(Intent.CATEGORY_LAUNCHER);
            intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK | Intent.FLAG_ACTIVITY_RESET_TASK_IF_NEEDED);
            intent.setComponent(name);
            intent.putExtra(Intent.EXTRA_TEXT, message);
            context.startActivity(intent);
            break;
        }
    }
}
catch(final ActivityNotFoundException e) {
    Log.i("mufumbo", "no twitter native",e );
}

October 18, 2009

RSS parsing optimization for bandwidth and processing time with SAX and httpclient – pooling scripts

Filed under: android, maintainability, performance, programming — Tags: , , , — mufumbo @ 3:55 pm

My server was having a constant income traffic of 1.7mb/s for a service that download RSS from the internet and process them. Basically it need to return the last updates of multiple RSS feeds. It’s a very basic pooling system, but it was downloading too much data for just 15.000 active users. The growth wasn’t looking very feasible..

I was using the ROME java library to parse the XML. So far so good, the problem was that it downloads the whole feed and process it all. With my application scope I don’t need to download the whole RSS, just the new entries that i didn’t downloaded yet.

The solution was to use a custom SAX RSS parser, looping through the “” tags and identifying “”. In this way i can parse item per item, and identify if the current item is not updated, so I can abort the http connection and stop the download of the feed. I wish that ROME had an option to do that, like “stop processing when ‘publishedDate’ minor than..”.

The impact on bandwidth usage and processing time was impressive:

If someone is interested I can post and explain the java class. It’s compatible with com.sun.syndication.feed.synd and uses the SyndEntry and SyndFeed interfaces.

September 17, 2009

My first public android app – craigslist notification


logo

This application alert the users when new stuff is posted to craigslist. In this way they can get the best deals as soon as they are registered.

The application is totally free and doesn’t use ads either in current or future versions. There is no form of monetization associated with this application. I am using my new server that i am renting from hetzner.
The application does not require registration and does not store information about its usage on the server.

Features

  • Enable the user to create notifications for certain keywords;
  • Allow to have all filtering that craigslist.org has;
  • Has all cities that craigslist.org has;
  • Preferences menu for configuring the location and network options;
  • Mark posts as favorite to read at a later time;
  • The relevant posts are downloaded on the phone, so they can be read later without network;
  • Faster navigation, since relevant posts are downloaded in batch;

Technical details

  • It periodically checks for new posts;
  • In each check it download *only* the updated data, which should be
    small after the initial download;
  • If no update is available it does not download anything at all. This proves to use less bandwidth than a normal navigation app, since:
    • Only relevant data is downloaded;
    • It never download duplicated data two times;
    • It’s not like RSS feeds that it’s the phone downloading and pooling the feeds every time.
      The phone only donwload the updated data one and do it just one time.

Bandwidth usage

  • For example, a download of 100 new posts takes 50kb of
    internet bandwidth.
  • The daily bandwidth will depend on the number of
    notifications that you are monitoring and the number of times that
    your notifications get updated.
  • To reduce bandwidth, try to be specific in your notifications.
  • For example: try to use “honda civic” instead of “car”

Screenshots

  • Main screen – notification list

    Main screen. This is where your notifications are listed:

  • Posts listing

    When you click on one notification, you go to the post listing.

    Notice that you can edit the previously configured notification by clicking on this menu item.

  • Post detail

    Once you click on one post you will see this screen which displays the post details.

    You are not required to be connected to the network to see the already downloaded posts.

    Notice that you can mark posts as favorite to read them later. The favorite page is accessed from the main menu.

  • Notification

    When there are new posts the app displays a notification on your phone. This can be disabled in the preferences.

August 5, 2009

reading java-style properties file in PHP

Filed under: caveats, php, programming — Tags: , , , , — mufumbo @ 4:46 am

It’s very strange that PHP only support the “parse_ini_string” as configuration function. I don’t like it at all! It has problems handling quotes, new lines, and other caveats.

The only benefit of parse_ini_string against Java Properties file is that it can handle “arrays”, but I don’t think that’s a benefit anyways. I had some trouble because I was wanting to use properties file in php for translations, since I only found buggy versions on the net I had build my own:

<?php
function parse_properties($txtProperties) {
 $result = array();

 $lines = split("\n", $txtProperties);
 $key = "";

 $isWaitingOtherLine = false;
 foreach($lines as $i=>$line) {

 if(empty($line) || (!$isWaitingOtherLine && strpos($line,"#") === 0)) continue;

 if(!$isWaitingOtherLine) {
 $key = substr($line,0,strpos($line,'='));
 $value = substr($line,strpos($line,'=') + 1, strlen($line));
 }
 else {
 $value .= $line;
 }

 /* Check if ends with single '\' */
 if(strrpos($value,"\\") === strlen($value)-strlen("\\")) {
 $value = substr($value, 0, strlen($value)-1)."\n";
 $isWaitingOtherLine = true;
 }
 else {
 $isWaitingOtherLine = false;
 }

 $result[$key] = $value;
 unset($lines[$i]);
 }

 return $result;
}
?>

This function can be used to create a php properties class. It should have the same behavior as the Java properties, so it should handle ” quotes and \ for new lines.

Sorry for the bad identation, wordpress hasn’t been very nice. Let me know if it have bugs :)

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