Lets continue the "Heroes of Java" series. Today's interview has been planned nearly since the launch of the series and I knew that it would be a tough one to get. I know Marcus since a few years now and he is always busy providing the best diagnostic tools to Java developers. Thanks for finally joining, Marcus! It is a pleasure to have you here! Marcus Hirt is one of the founders of Appeal Virtual Machines, the company that created the JRockit JVM. He is currently working as Team Lead for the Java Mission Control team. In his spare time he enjoys coding on his many pet projects, composing music, and scuba diving. Marcus has contributed JRockit related articles, whitepapers, tutorials, and webinars to the JRockit community, and has been an appreciated speaker at various conferences, such as Oracle Open World and Java One. He is also one of the two authors behind a popular book about JVM technology (link to my review). General Part Who are you? I am a computer aficionado with a strikingly unmodern and lengthy romance with typed languages, profiling and diagnostics. I have three kids and a lovely wife, so right now there isn't much spare time to go around. When there was, I used to compose music, play the piano, scuba dive and do martial arts. Your official job title at your company? Consulting Member of Technical Staff Do you care about it? I care about being appreciated for my work. The title itself means nothing. Do you speak foreign languages? Which ones? Swedish is my native tongue and my preferred language for anything that is not computer related. That said, since most of the terminology in our business is in English, I actually prefer English when talking shop. I am half Swiss, and I did spend some time at Real Gymnasium Kirchenfeld in Bern. I haven't used my German since then though, so it is beyond rusty. How long is your daily "bootstrap" process? (Coffee, news, email) If you don't count email, it is almost non-existent. However, in my role as a team leader, email is chewing up a good portion of the morning these days. Thanks to the excellent mass transit system in Stockholm, that is usually taken care of before I arrive at the office. At least during the winters. During the summers I usually drive my motorcycle to work. Twitter You have a twitter handle? Why? I indiscriminately sign up for all social services. Then I find that I don't use most of them. Twitter is a bit of a exception, since I do tend to read what others write. When I do tweet it is mostly about new obscure and/or unsupported features in the Hotspot JDK. My twitter handle is @hirt. Whom are you following in general? I mostly follow people that I know and respect in the Java community. Do you have a personal "policy" for twitter? I try to avoid it at work. Does your company restrict or encourage you with your twitter usage? Oracle has neither actively encouraged nor restricted my twitter usage. The only time I can recall a company actively encouraging me to engage in some official social capacity was some years ago, when BEA tried to encourage people to blog. I’ve since moved away from the official company blog, because of a tooling issue. Work What's your daily development setup? (OS/IDE/VC/other Tools) Since the first target platform for JRockit was Windows, I've stuck with Windows at work. I am using Windows 7/Eclipse/Perforce and Visual Studio. At home I am using Mac OS X/Eclipse/Git&Perforce and XCode. Which is the tool providing most productivity to your work? These days: Eclipse. No doubt. Your preferred way of interacting with co-workers? Face to face for longer discussions. IM is good for smaller things, since you can choose when to handle the interrupt, whilst still being fairly interactive. What's your favorite way of managing your todo's? Pen and paper. Stone age, right? If you could make a wish for a job at your favorite company: What would that be? Whichever would give me the resources to attack some of the high impact development projects on my "want to do" list. Oracle is currently quite a good place to be. Java You're programming in Java. Why? To be honest, I am not exclusively programming in Java. When I do, it is because it is one of the programming environments in which I find myself to be the most productive. It may not be the least verbose or most elegant of languages, but the tooling and debugging capabilities are top notch. Not to mention that some intrinsic features of the language itself, such as the memory management, makes it easier to write error free code. Also, since there has been competition around the JVM for more than a decade, the JVMs for Java are really quite sophisticated. Not to mention fast. What's least fun with Java? It is unnecessarily verbose (more type inference please), type erasure (ever sent in a class to your generic type to have a chance of knowing what runtime type it is?), and any and all things that makes the illusion of an all powerful runtime break down. In a perfect world, a Java programmer should not have to worry about the details of the JVM configuration. For instance, why should I need to estimate how much space I will need for constants and class metadata (perm gen)? Thankfully there is work being done on this as we speak; the perm gen is scheduled for removal in JDK 8. I think there is a lot to be said for improving the usability of the JVM. If you could change one thing with Java, what would that be? There are many who want Java to be everything to everyone. I don't subscribe to that view. Instead, let's make it easy to run whatever language you want on the JVM. That said, if I could change something about the implementation, I would probably want a thread local garbage collector. One with insanely good heuristics as to when to back off and stop handling an object thread locally. Then there are some other things, but since I may start working on them soon, I would rather keep them to myself for now. :) What's your personal favorite in dynamic languages? Ruby is cute. I especially like the implementation on the JVM (JRuby). Which programming technique has moved you forwards most and why? When I first started my education at the Royal Institute of Technology, I had already programmed in various languages, such as Pascal, C and assembly. I really thought I had things figured out, until I came to the first computer science course. There I got confronted with SICP and Scheme. That was IMHO a genius move by the computer science department. All the cocky kids with prior experience, such as myself, got a rich serving of humble-pie. Functional programming taught me very elegant ways of expressing myself. Kudos to MIT and Sussman et al. What was the biggest project you've ever worked on? JRockit and JRockit Mission Control. I was one of the founders of Appeal (Appeal Virtual Machines & Appeal Software Solutions), a big project in itself. Which was the worst programming mistake you did? Well, maybe not strictly a programming mistake, but one of the worst red-face issues I've done is when a JRockit performance counter was slightly misspelled - the 'o' was accidentally dropped from *count. The bug report stated that "the customer was not amused". I must admit I was though. Another fun, deliberate, "mistake" was when I added the following three lines to one of the Mission Control property files: ------ # :) We just felt that we needed this one translated... # /The MC team Template_DEFAULT_TEMPLATE_NAME=All your base are belong to us! ------ I was hoping to get a cynical remark back from the translation team, but they just translated it the best they could. Heh. Finally, one of the worst programming mistakes in recent history was in a small start-up project. A hash code calculation error caused some subtle errors to one of many data points in a running production system. I finally solved the problem when I got fiber installed at home and got bold. In desperation I started a node with jdwp turned on, and I then proceeded to set break points and evaluate code remotely over an ssh tunnel. The latency was so low that it almost felt like a local debugging session. Crazy, but you gotta love Java for providing you with options. ;)

NetBeans workspace coloring has traditionally preferred dark text over bright background. However, under some circumstances, e.g., in low-light conditions a darker workspace coloring may be beneficial or at least perceived as easier on the eyes. For those users preferring dark workspaces there were only insufficient options available so far. It has been possible to choose a dark editor color style, but such choice would not be reflected outside editor window - the workspace would thus suffer from the strong contrast between the dark editor panel and the bright background of the rest of the workspace. Although it is generally possible to change the look and feel of the operating system as a whole, this is not always desirable and always remains suboptimal with respect to NetBeans; for instance the design of icons can not be adjusted in this way. In current NetBeans daily builds (February 2013) we provide two new Look-and-Feels to address this issue. They offer two slightly different visual styles: Dark Nimbus provides dark content panels on brighter grayish workspace, while Dark Metal provides more uniformly dark workspace. The designs aim at providing well-balanced and legible dark IDE workspace as a whole. To switch NetBeans to one of the new LaFs do the following: in Tools->Options->Miscellaneous->Windows choose either Dark Metal or Dark Nimbus in the "Preferred look and feel" combo box. Then in Tools->Options->Fonts & Colors choose Norway Today in the "Profile" combo box. Restart NetBeans. The two new LaFs represent work in progress, but have already reached a reasonably usable state. We will keep them improving. Support for the two dark LaFs is too new and as such could not make it to NetBeans 7.3 release schedule, but will be added to NetBeans 7.3.1. It is already included in daily builds . A simpler version of Dark Nimbus is also available as downloadable plugin . Please report any remaining issues (especially legibility issues, but also improperly colored UI component leftovers) as part of or in relation to Bugzilla Issue #225542.

This post comes from Miguel Angel Nieto at the MySQL Performance Blog. MySQL 5.6 is GA! Now we have new things to play with and in my personal opinion the most interesting one is the new Global Transaction ID (GTID) support in replication. This post is not an explanation of what is GTID and how it works internally because there are many documents about that: http://dev.mysql.com/doc/refman/5.6/en/replication-gtids-concepts.html One thing that worths to mention is that if you want GTID support log_slave_updates will need to be enabled in slave server and the performance impact should be taken in account. Anyway, this post tends to be more practical, we will see how to create/restore new slaves from a master using GTID. How to set up a new slave The first thing that we need to know is that now Binary Logs and Position are not needed anymore with GTID enabled. Instead we need to know in which GTID is the master and set it on the slave. MySQL keeps two global variables with GTID numbers on it: gtid_executed: it contains a representation of the set of all transaction logged in the binary log gtid_purged: it contains a representation of the set of all transactions deleted from the binary log So now, the process is the following: take a backup from the master and store the value of gtid_executed restore the backup on the slave and set gtid_purged with the value of gtid_executed from the master The new mysqldump can do those tasks for us. Let’s see an example of how to take a backup from the master and restore it on the slave to set up a new replication server. master > show global variables like 'gtid_executed'; +---------------+-------------------------------------------+ | Variable_name | Value | +---------------+-------------------------------------------+ | gtid_executed | 9a511b7b-7059-11e2-9a24-08002762b8af:1-13 | +---------------+-------------------------------------------+ master > show global variables like 'gtid_purged'; +---------------+------------------------------------------+ | Variable_name | Value | +---------------+------------------------------------------+ | gtid_purged | 9a511b7b-7059-11e2-9a24-08002762b8af:1-2 | +---------------+------------------------------------------+ Now we take a backup with mysqldump from the master: # mysqldump --all-databases --single-transaction --triggers --routines --host=127.0.0.1 --port=18675 --user=msandbox --password=msandbox > dump.sql It will contain the following line: # grep PURGED dump.sql SET @@GLOBAL.GTID_PURGED='9a511b7b-7059-11e2-9a24-08002762b8af:1-13'; Therefore during the dump recover process on the slave it will set GTID_PURGED to the GTID_EXECUTED value from the master. So now, we just need to recover the dump and start the replication: slave1 > show global variables like 'gtid_executed'; +---------------+-------+ | Variable_name | Value | +---------------+-------+ | gtid_executed | | +---------------+-------+ slave1 > show global variables like 'gtid_purged'; +---------------+-------+ | Variable_name | Value | +---------------+-------+ | gtid_purged | | +---------------+-------+ slave1 > slave1> source test.sql; [...] slave1 > show global variables like 'gtid_executed'; +---------------+-------------------------------------------+ | Variable_name | Value | +---------------+-------------------------------------------+ | gtid_executed | 9a511b7b-7059-11e2-9a24-08002762b8af:1-13 | +---------------+-------------------------------------------+ slave1 > show global variables like 'gtid_purged'; +---------------+-------------------------------------------+ | Variable_name | Value | +---------------+-------------------------------------------+ | gtid_purged | 9a511b7b-7059-11e2-9a24-08002762b8af:1-13 | +---------------+-------------------------------------------+ The last step is to configure the slave using the auto-configuration method of GTID: slave1 > CHANGE MASTER TO MASTER_HOST="127.0.0.1", MASTER_USER="msandbox", MASTER_PASSWORD="msandbox", MASTER_PORT=18675, MASTER_AUTO_POSITION = 1; How to restore a slave in a bad and fast way Let’s imagine that our slave has been down for several days and the binary logs from the master have been purged. This is the error we are going to get: Slave_IO_Running: No Slave_SQL_Running: Yes Last_IO_Error: Got fatal error 1236 from master when reading data from binary log: 'The slave is connecting using CHANGE MASTER TO MASTER_AUTO_POSITION = 1, but the master has purged binary logs containing GTIDs that the slave requires.' So, let’s try to solve it. First we have the bad and fast way, that is, point to another GTID that the master has in the binary logs. First, we get the GTID_EXECUTED from the master: master > show global variables like 'GTID_EXECUTED'; +---------------+-------------------------------------------+ | Variable_name | Value | +---------------+-------------------------------------------+ | gtid_executed | 9a511b7b-7059-11e2-9a24-08002762b8af:1-14 | +---------------+-------------------------------------------+ And we set it on the slave: slave> set global GTID_EXECUTED="9a511b7b-7059-11e2-9a24-08002762b8af:1-14" ERROR 1238 (HY000): Variable 'gtid_executed' is a read only variable Error! Remember, we get the GTID_EXECUTED from the master and set is as GTID_PURGED on the slave. slave1 > set global GTID_PURGED="9a511b7b-7059-11e2-9a24-08002762b8af:1-14"; ERROR 1840 (HY000): GTID_PURGED can only be set when GTID_EXECUTED is empty. Error again, GTID_EXECUTED should be empty before changing GTID_PURGED manually but we can’t change it with SET because is a read only variable. The only way to change it is with reset master (yes, on a slave server): slave1> reset master; slave1 > show global variables like 'GTID_EXECUTED'; +---------------+-------+ | Variable_name | Value | +---------------+-------+ | gtid_executed | | +---------------+-------+ slave1 > set global GTID_PURGED="9a511b7b-7059-11e2-9a24-08002762b8af:1-14"; slave1> start slave io_thread; slave1> show slave status\G [...] Slave_IO_Running: Yes Slave_SQL_Running: Yes [...] Now, if you don’t get any error like primary/unique key duplication then you can run the pt-table-checksum and pt-table-sync. How to restore a slave in a good and slow way The good way is mysqldump again. We take a dump from the master like we saw before and try to restore it on the slave: slave1 [localhost] {msandbox} ((none)) > source test.sql; [...] ERROR 1840 (HY000): GTID_PURGED can only be set when GTID_EXECUTED is empty. [...] Wop! It is important to mention that these kind of error messages can dissapear on the shell buffer because the restore of the dump will continue. Be cautious. Same problem again so same solution too: slave1> reset master; slave1> source test.sql; slave1> start slave; slave1> show slave status\G [...] Slave_IO_Running: Yes Slave_SQL_Running: Yes [...] Conclusion With the new GTID we need to change our minds. Now binary log and position is not something we need to take in account, gtid_executed and gtid_purged are our new friends. Xtrabackup still doesn’t support it but we are working on it. I will update this post and create a one when we publish a xtrabackup version with full support of GTID.

usually, one of the first things i see if i launch eclipse is this dialog: select a workspace dialog actually, that ‘workspace’ thing is one of the most important things in eclipse to understand. to mess around it can cause a lot of pain. so i have collected some ‘lessons learned’ around workspaces. the workspace .metadata folder the workspace is where eclipse stores that .metadata folder: workspace metadata folder in this folder, eclipse stores all the workspace settings or preferences i configure e.g. using the menu window > preferences . sometimes that .metadata folder is named ‘framework’ too. e.g. if i’m are asked by eclipse to store some settings in the ‘frame work’ then this means it will be stored in the .metadata. eclipse uses this folder as well to store internal files and data structures. and many plugins store their settings in here to. consider the content of this folder as a ‘black box’: so do not change it, do not touch it unless you *really* know what you are doing! do not copy or move that folder. if you want to copy/share your workspace settings, then do *not* copy the .metadata folder, as typically you cannot use this folder on another machine or for another user. if you want to transfer/copy your settings, then see this post . workspace and eclipse versions as eclipse stores information in the .metadata workspace structure, the data/format might be different from version of eclipse to another (e.g. from one version of codewarrior to another). while using the same workspace with different versions of eclipse might work, it is *not* recommended. the eclipse community tries hard to keep things compatible, but using a different workspace for different eclipse versions is what i recommend. i started to name my workspace(s) like ‘wsp_lecture_10.2′ or ‘wsp_lecture_10.3′ to show that i’m using it for a specific version of codewarrior. workspace and projects this leads to the question: “do i have to duplicate then my projects if using with different versions of eclipse in parallel?” the answer is ‘no’. because the workspace folder does *not* have to have the projects in it (as folders). they can, but it is not needed. for example i have different workspaces (“wsp_10.3″, “wsp_10.2″), but my projects are in the “projects” folder somewhere else on my disk. what i do is to import the projects into each workspace, keep the projects in their original folder location. the menu file > import > general > existing projects into workspace can be used, with ‘copy projects into workspace’ * unchecked *: importing projects into workspace an easy trick is to drag&drop the project folders into eclipse: that’s much faster and simpler in my view than using above dialog. tip: showing the current workspace in the title bar using multiple workspaces can be confusing at some time. see this post how you can show the workspace in the application title: workspace shown in title bar processor expert processor expert has a special setting in the workspace pointing to its ‘data base’. that data base is inside the installation folder, in the mcu\processorexpert folder. if a launch eclipse and use a workspace from a different installation, i get a warning dialog: processor expert workspace warning: current worksapce is configured to use data from another installation of processor expert. that path setting of processor expert (pointing to the installation folder) is in my view the biggest argument to *not* share a workspace between different versions of eclipse. pressing the ‘open preferences’ opens the settings, and with ‘restore defaults’ it will (after a restart of eclipse) use the new installation path: processor expert directory that warning might not come up if using multiple installations of codewarrior. it seems that as long there is a valid path to a processor expert data base, the warning might not show up, and it will use that data base. that can lead to weird behaviour, so better check that the path in the workspace setting is pointing to the right folder. workspace dialog on startup remember that dialog at the beginning of this post? if i want to change if (and what) is shown at eclipse startup, then this is configured with the menu window > preferences > general > startup and shutdown : startup and workspaces in this dialog i can remove items from the list (e.g. if a workspace folder does not exist any more). tabula rasa as eclipse stores a lot of information in the workspace .metadata, that folder can grow to a substantial size (several hundreds of mbytes, depending on usage and configuration). one reason is because eclipse stores local history and undo information into that .metadata folder. just have a look at .metadata\.plugins\org.eclipse.core.resources\.history so from time to time (especially if i think that eclipse is slowing down), i export my workspace settings ( file > export > general > preferences , see copy my workspace settings ) and re-import it again into the new workspace. summary eclipse stores all its workspace settings and files in the .metadata folder. never touch/copy/change/move the .metadata folder. use different workspaces for each eclipse version. store the projects outside of the workspace if you want to share them across different eclipse versions. happy workspacing

As you may be aware, the JDK 8 Early Access is now available for download. This allows Java developers to experiment with some of the new language and runtime features of Java 8. One of these features is the complete removal of the Permanent Generation (PermGen) space which has been announced by Oracle since the release of JDK 7. Interned strings, for example, have already been removed from the PermGen space since JDK 7. The JDK 8 release finalizes its decommissioning. This article will share the information that we found so far on the PermGen successor: Metaspace. We will also compare the runtime behavior of the HotSpot 1.7 vs. HotSpot 1.8 (b75) when executing a Java program “leaking” class metadata objects. The final specifications, tuning flags and documentation around Metaspace should be available once Java 8 is officially released. Metaspace: A new memory space is born The JDK 8 HotSpot JVM is now using native memory for the representation of class metadata and is called Metaspace; similar to the Oracle JRockit and IBM JVM's. The good news is that it means no more java.lang.OutOfMemoryError: PermGen space problems and no need for you to tune and monitor this memory space anymore…not so fast. While this change is invisible by default, we will show you next that you will still need to worry about the class metadata memory footprint. Please also keep in mind that this new feature does not magically eliminate class and classloader memory leaks. You will need to track down these problems using a different approach and by learning the new naming convention. I recommend that you read the PermGen removal summary and comments from Jon on this subject. In summary: PermGen space situation This memory space is completely removed. The PermSize and MaxPermSize JVM arguments are ignored and a warning is issued if present at start-up. Metaspace memory allocation model Most allocations for the class metadata are now allocated out of native memory. The klasses that were used to describe class metadata have been removed. Metaspace capacity By default class metadata allocation is limited by the amount of available native memory (capacity will of course depend if you use a 32-bit JVM vs. 64-bit along with OS virtual memory availability). A new flag is available (MaxMetaspaceSize), allowing you to limit the amount of native memory used for class metadata. If you don’t specify this flag, the Metaspace will dynamically re-size depending of the application demand at runtime. Metaspace garbage collection Garbage collection of the dead classes and classloaders is triggered once the class metadata usage reaches the “MaxMetaspaceSize”. Proper monitoring & tuning of the Metaspace will obviously be required in order to limit the frequency or delay of such garbage collections. Excessive Metaspace garbage collections may be a symptom of classes, classloaders memory leak or inadequate sizing for your application. Java heap space impact Some miscellaneous data has been moved to the Java heap space. This means you may observe an increase of the Java heap space following a future JDK 8 upgrade. Metaspace monitoring Metaspace usage is available from the HotSpot 1.8 verbose GC log output. Jstat & JVisualVM have not been updated at this point based on our testing with b75 and the old PermGen space references are still present. Enough theory now, let’s see this new memory space in action via our leaking Java program… PermGen vs. Metaspace runtime comparison In order to better understand the runtime behavior of the new Metaspace memory space, we created a class metadata leaking Java program. You can download the source here. The following scenarios will be tested: Run the Java program using JDK 1.7 in order to monitor & deplete the PermGen memory space set at 128 MB. Run the Java program using JDK 1.8 (b75) in order to monitor the dynamic increase and garbage collection of the new Metaspace memory space. Run the Java program using JDK 1.8 (b75) in order to simulate the depletion of the Metaspace by setting the MaxMetaspaceSize value at 128 MB. JDK 1.7 @64-bit – PermGen depletion Java program with 50K configured iterations Java heap space of 1024 MB Java PermGen space of 128 MB (-XX:MaxPermSize=128m) As you can see form JVisualVM, the PermGen depletion was reached after loading about 30K+ classes. We can also see this depletion from the program and GC output. Class metadata leak simulator Author: Pierre-Hugues Charbonneau http://javaeesupportpatterns.blogspot.com ERROR: java.lang.OutOfMemoryError: PermGen space Now let’s execute the program using the HotSpot JDK 1.8 JRE. JDK 1.8 @64-bit – Metaspace dynamic re-size Java program with 50K configured iterations Java heap space of 1024 MB Java Metaspace space: unbounded (default) As you can see from the verbose GC output, the JVM Metaspace did expand dynamically from 20 MB up to 328 MB of reserved native memory in order to honor the increased class metadata memory footprint from our Java program. We could also observe garbage collection events in the attempt by the JVM to destroy any dead class or classloader object. Since our Java program is leaking, the JVM had no choice but to dynamically expand the Metaspace memory space. The program was able to run its 50K of iterations with no OOM event and loaded 50K+ Classes. Let's move to our last testing scenario. JDK 1.8 @64-bit – Metaspace depletion Java program with 50K configured iterations Java heap space of 1024 MB Java Metaspace space: 128 MB (-XX:MaxMetaspaceSize=128m) As you can see form JVisualVM, the Metaspace depletion was reached after loading about 30K+ classes; very similar to the run with the JDK 1.7. We can also see this from the program and GC output. Another interesting observation is that the native memory footprint reserved was twice as much as the maximum size specified. This may indicate some opportunities to fine tune the Metaspace re-size policy, if possible, in order to avoid native memory waste. Now find below the Exception we got from the Java program output. Class metadata leak simulator Author: Pierre-Hugues Charbonneau http://javaeesupportpatterns.blogspot.com ERROR: java.lang.OutOfMemoryError: Metadata space Done! As expected, capping the Metaspace at 128 MB like we did for the baseline run with JDK 1.7 did not allow us to complete the 50K iterations of our program. A new OOM error was thrown by the JVM. The above OOM event was thrown by the JVM from the Metaspace following a memory allocation failure. #metaspace.cpp Final words I hope you appreciated this early analysis and experiment with the new Java 8 Metaspace. The current observations definitely indicate that proper monitoring & tuning will be required in order to stay away from problems such as excessive Metaspace GC or OOM conditions triggered from our last testing scenario. Future articles may include performance comparisons in order to identify potential performance improvements associated with this new feature. Please feel free to provide any comment.

the great thing with eclipse is that you can configure a lot. in general, i’m happy with most of the defaults in eclipse and codewarrior. here are my top 10 things i change in eclipse to make it even better: add -showlocation to the eclipse startup command line: show workspace location in the title bar disable the heuristik settings for the indexer : fixing the eclipse index disable build (if required) for the debugger: speeding up the debug launch in codewarrior using spaces and not tabs: spaces vs. tabs in eclipse highlight the selected line : color makes the difference! configuring more hovers : hovering and debugging enabling static software analysis : free static code analysis with eclipse processor expert expert settings: enabling the expert level in processor expert custom dictionary settings: eclipse spell checker show line numbers : eclipse and line numbers i don’t have to waste time to change the settings for each of my workspaces: after i have changed the settings, i can simply export and import them again into another workspace: change my preferences using the menu window > preferences use the menu file > export > general > preferences and save the settings in a file: file export switch to the new workspace use the menu file > import > general > preferences to import the settings from the file: file import happy customizing

Being an itinerant programmer one of the things I've noticed over the years is that every project you come across seems to have a slightly different way of organising its Maven modules. There seems to be no conventional way of characterising the contents of a project's sub-modules and not that much discussion on it either. This is strange, as defining the responsibilities of your Maven modules seems to me to be as critical as good class design and coding technique to a project's success. So, in light of this dearth of wisdom, here's my two penneth worth... When you first come across a new project, you'll generally find a layout convention that vaguely matches that defined by the Better Builds With Maven manual. The 'clean' project directory usually contains a POM file, a src folder and several sub-modules, each in their own subdirectory, as shown in the diagram below: If we all agree that this is the standard way of approaching the top level of project layout (and I have seen it done slightly differently) then there seems to be three different approaches taken when organising the responsibilities of each of a project's sub-modules. These are: Totally haphazardly. By class type. By functional area. I'm not going to linger on those projects that are organised seemingly without any structure or order except to say that they probably started off well organised but were not designed well enough to endure the changes forced upon them. In saying that a project's sub-modules are organised 'by class type', I mean that modules are used to group together all classes that comprise, but are not limited to, a layer in the program's architecture. For example a module could contain all classes that make up the program's service or persistence layers or a module could contain all model class (i.e. beans). Conversely, in saying that a project's sub-modules are organised by functional area I'm talking about a situation where each module contains, as close as possible, a vertical slice of the application, including model beans, service layer, controllers etc. If the truth be told then there are any number of ways to organise your project's sub-modules. Most project set-ups are fairly flat in structure, which is what I've demonstrated above; however, if you take a look at Erik Putrycz's 2009 talk Maven – or how to automate java builds, tests and version management with open source tools, he demonstrates that you can have modules within modules within modules. In order to explore this a little further, I'm going to invent my usual preposterously contrived scenario and in this scenario, you've got to write a program for a Welsh dental practice owned by a man called Jones also known locally as 'Jones The Driller'. The requirements would be pretty standard, I suspect, for a dental practice and would include handling: Patients details: name, address, DOB, phone number etc. Medical records, including treatments and outcomes. Appointments. Accounting, e.g. sales, purchase, wages etc. Auditing: as in who did what to whom... As a solution to Jones The Driller's problem, you propose that you write a multi-module web application based upon Spring, MVC and tomcat that, when assembled, has a standard 'n' tier design of a mySQL database, a database layer, service layer, a set of controllers and some JSPs that comprise the view. In creating your project your idea is to organise your sub-modules 'by class type' and you come up with the following module organisation, shown below roughly in build dependency order dentists-model dentists-utils dentist-repository dentists-services dentists-controllers dentists-web ...which on your screen looks something like this: Your dentists-model module contains the project's beans that model object used from the persistence layer right up to the JSPs. dentists-repository, dentists-services and dentists-controllers reflect the various layers of your application, with dentists-web module containing all the JSPs, CSS and other view paraphernalia. As for dentists-utils, well every project has a utils module where all the really useful, but disparate classes end up. Meanwhile, in a different universe, a different version of you decides to organise your project's sub-modules by functional area and you come up with the following breakdown: dentists-utils dentists-audit dentists-user-details dentists-medical-records dentists-appointments dentists-accounts dentists-repository dentists-integration dentists-web In this scenario, the build order is somewhat different; virtually all modules will depend upon dentists-utils and, depending upon your exact audit requirements, most modules will rely upon dentists-audit. You can also see in the following images that the sub-module package structure has been arranged on layer and type boundaries in that each module has its own model, repository (which contains interface definitions only) services and controller packages and that the layout of each module is identical at the top level. Another discussion to have here is the organisation of your project's package structure, where you can ask the same kind of questions: do you organise 'by class type' or 'by functional area' as shown above? You may have noticed that the dentists-repository modules can be fairly near the end of the build cycle as it only contains the implementation of the repository classes and not their interface definitions. You may have also noticed that dentists-web is again a separate module. This is because you're a pretty savvy business guy and in keeping the JSPs etc. in their own module, you hope to re-skin your app and sell it to that other Welsh dentist down the road: Williams The Puller. From a test perspective, each module contains its own unit tests, but there's a separate integration test module that, as it'll take longer to execute can be run when required. There are generally two ways of defining integration tests: firstly by putting them in their own module, which I prefer, and secondly by using a integration test naming convention such as somefileIT.java, and running all *IT.java files separately to all *Test.java files. Your two identical selves have proposed two different solutions to the same problem, so I guess that it's now time to takes a look at the pros and cons of each. Taking the 'by class type' solution first, what can be said about it? On the plus side, it's pretty maintainable in that you always known where to find stuff. Need a service class? Then that's in the dentist-service module. Also, the build order is very straight forward. On the down side, organisation 'by class type' is prone to problems with circular dependencies creeping in and classes with totally different responsibilities are all mixed up together making it difficult to re-use functionality in other projects without unnecessarily dragging in the who shebang. So, what about the pros and cons of the 'by functional area' approach? To my way of thinking, given the package structure of each module, it's just about as easy to locate a class using this technique as it is when using 'by class type'. The real benefit of using this approach is that it's far simpler to re-use a functional area of code in other projects. For example, I've worked on many projects in different companies and have implemented auditing several times. Each time I implement it I usually do it in roughly the same way, so wouldn't it be good just to reuse the first implementation? Not withstanding code ownership issues... The same idea also applies to dentists-user-details; the requirement to manage names and addresses applies equally as well to a shoe sales web site as it does a dental practice. And the downside? One of the benefits of this approach is that the modules are highly decoupled, but from experience no matter how hard you try, you always end up with more coupling that you'd like. You may have already spotted that both of these proposals are not 100% pure; 'by class type' contains a bit of 'by functionality' and conversely 'by functional area' contains a couple of 'by class type' modules. This may be avoidable, but I'm purposely being pragmatic. As I said earlier you always see a utils module in a project. Furthermore creating a separate database module allows you to change your project's database implementation fairly easily, which may make testing easier in some circumstances and likewise, having a separate web module allows you to re-skin your code should you be lucky enough to sell the same product to multiple customers with their own branding. Finally, one of the unwritten truths in software development is that once you've organised your project into its sub-modules you'll rarely get the opportunity to reorganise and improve them: there usually isn't the time or the political will as doing so costs money; however, it should be remembered that, in Agile terms, project module composition is, like code, a form of technical debt, which if done badly also costs you a lot of cash. It therefore seems a really good idea, as a team, to plan out your project thoroughly before starting to code. So be radical, do some design or have a meeting, you know it'll be worth it in the end.

I’ve been working in some Python Solr client code. One area where bugs have cropped up is in query terms that need to be escaped before passing to Solr. For example, how do you send Solr an argument term with a “:” in it? Or a “(“? It turns out that generally you just put a \ in front of the character you want to escape. So to search for “:” in the “funnychars” field, you would send q=funnychars:\:. Php programmer Mats Lindh has solved this pretty well, using str_replace. str_replace is a convenient, general-purpose string replacement function that lets you do batch string replacement. For example you can do: $matches = array("Mary","lamb","fleece"); $replacements = array("Harry","dog","fur"); str_replace($matches, $replacements,"Mary had a little lamb, its fleece was white as snow"); Python doesn’t quite have str_replace. There is translate which does single character to single character batch replacement. That can’t be used for escaping because the destination values are strings(ie “\:”), not single characters. There’s a general purpose “str_replace” drop-in replacement at this Stackoverflow question: edits =[("Mary","Harry"),("lamb","dog"),("fleece","fur")]# etc.for search, replace in edits: s = s.replace(search, replace) You’ll notice that this algorithm requires multiple passes through the string for search/replacement. This is because that earlier search/replaces may impact later search/replaces. For example, what if edits was this: edits =[("Mary","Harry"),("Harry","Larry"),("Larry","Barry")] First our str_replace will replace Mary with Harry in pass 1, then Harry with Larry in pass 2, etc. It turns out that escaping characters is a narrower string replacement case that can be done more efficiently without too much complication. The only character that one needs to worry about impacting other rules is escaping the \, as the other rules insert \ characters, we wouldn’t want them double escaped. Aside from this caveat, all the escaping rules can be processed from a single pass through the string which my solution below does, performing a heck of a lot faster: # These rules all independent, order of# escaping doesn't matter escapeRules ={'+':r'\+','-':r'\-','&':r'\&','|':r'\|','!':r'\!','(':r'\(',')':r'\)','{':r'\{','}':r'\}','[':r'\[',']':r'\]','^':r'\^','~':r'\~','*':r'\*','?':r'\?',':':r'\:','"':r'\"',';':r'\;',' ':r'\ '}defescapedSeq(term):""" Yield the next string based on the next character (either this char or escaped version """forcharin term:ifcharin escapeRules.keys():yield escapeRules[char]else:yieldchardefescapeSolrArg(term):""" Apply escaping to the passed in query terms escaping special characters like : , etc""" term = term.replace('\\',r'\\')# escape \ firstreturn"".join([nextStr for nextStr in escapedSeq(term)]) Aside from being a good general solution to this problem, in some basic benchmarks, this turns out to be about 5 orders of magnitude faster than doing it the naive way! Pretty cool, but you’ll probably rarely notice the difference. Nevertheless it could matter in specialized cases if you are automatically constructing and batching large/gnarly queries that require a lot of work to escape. Anyway, enjoy! I’d love to hear what you think!

Here is a small code snippet which shows an utility class that offers two methods to compress and extract a Java byte array.

one of the nice things of modern ide’s are: they offer many extras for free. many times it is related to programming and coding. but i love as well the ones which makes things easier and better which is not directly related to the executed code. one thing eclipse offers is an on-the-fly spell-checking, similar to microsoft word: spellchecked sources hovering over the text offers me to correct the flagged error: initialization vs. initialisation but wait: is that example not spelled correctly? and indeed, eclipse offers to customize the spell checking. the option page is in the windows > preferences > general > editors > text editors > spelling page: spelling preferences ‘initialization’ vs. ‘initialisation’: that’s an ‘english us’ vs. english uk’ thing, and is easily changed. and i prefer the us english: changing dictionary with this, everything is ok now: not flagged any more after changing the platform dictionary, it usually takes a few minutes until the sources are checked again. but what if eclipse does not know a word? then it offers to add it to a dictionary: adding to the dictionary if i do not have a user dictionary yet, it will prompt a dialog: missing user dictionary if pressing ‘yes’, it will prompt the settings page from above where i can specify my user dictionary file: user defined dictionary the user dictionary is a normal text file with one word on each line. that makes it easy to edit and to have it in a version control system. i have one common dictionary file for all my workspaces. but of course it is possible to have different dictionaries per workspace, as the settings are per workspace too. summary i feel having reasonable spelled comments in the sources is just something an engineer should care about. and the eclipse spelling engine does not have to be as good as the one in ms word (which is pretty good in my view). but for making sources better something like correctly spelled comments is a plus. but only if the code works like a charm :mrgreen: happy spelling

I ran into an interesting little debugging conundrum recently with IntelliJ’s debugger and maven. I was loading a .war within the pre-integration-test phase of another module so I could run a set of intergration tests with the failsafe plugin that depend on that webapp being available. The purpose was to have that webapp loaded for some black box system testing at the end of the maven build. There was a test failure that was localized to this particular set of tests that I couldn’t quite sort out immediately. As usual, the next logical step is to attach a debugger. Since these tests depended on the environment being setup and that environment setup was performed via maven, I couldn’t just Run->Debug on the test itself as I normally can with tests in IntelliJ. So in IntelliJ I first set my breakpoints, go to the maven pane, and hit debug on the install goal for system module. The set of tests run and none of my breakpoints were hit. Bummer. It seems as though IntelliJ is not running maven with the debugging agent enabled even though I’ve explicity hit “Debug” on a maven goal. I’m not entirely sure what was going on with IntelliJ in this instance but here’s how I got around it. Ever since some earlier version of maven (2.0.8, I believe), maven has shipped with a little known executable in its bin/ directory named mvnDebug. In a nutshell, mvnDebug runs maven in all of its glory but includes the debugging arguments the jvm needs to listen for a debugger setup for you conveniently. > alias mvnDebug=/usr/share/maven/bin/mvnDebug > mvnDebug clean install Preparing to Execute Maven in Debug Mode Listening for transport dt_socket at address: 8000 This ends up being the equivalent of invoking java with the proper debugging arguments: java ... -Xdebug -Xrunjdwp:transport=dt_socket,address=8000,server=y,suspend=y Then in IntelliJ (or your IDE/debugger of choice) set your breakpoints and connect your debugger to localhost:8000 and voila! My breakpoints ended up getting hit and that particular issue was resolved in a matter of minutes.

When using an external API for WebHooks or Callbacks as discussed in Chapters 3 and 5 of Getting Started with Mule Cloud Connect; The API provider running somewhere out there on the web needs to callback your application that is happily running in isolation on your local machine. For an API provider to callback your application, the application must be accessible over the web. Sure, you could upload and test your application on a public facing server, but you may find it quicker and easier to work on your local development machine and these are typically behind firewalls, NAT, or otherwise not able to provide a public URL. You need a way to make your local application available over the web. There are a few good services and tools out there to help with this. Examples include ProxyLocal, and Forward.io. Alternatively, you can set up your own reverse SSH Tunnel if you already have a remote system to forward your requests, but this is cumbersome to say the least. I find Localtunnel to be an excellent fit for this need and localtunnel have just recently released v2 of its service with a host of new features and enhancements. More information can be found here: http://progrium.com/blog/2012/12/25/localtunnel-v2-available-in-beta/ Installing Localtunnel Those familiar with version 1 of the service will know that the v1 Localtunnel client was written in Ruby and required Rubygems to install it. The v2 client is now written in Python and can instead be installed via easy_install or pip. If instead you're interested in using Localtunnel v1, then I have wrote a previous blog post on the subject here: http://blogs.mulesoft.org/connector-callback-testing-local/ To get started, you will first need to check that you have Python installed. Localtunnel requires Python 2.6 or later. Most systems come with Python installed as standard, but if not you can check via the following command: $ python -version More info on installing Python can be found here: http://wiki.python.org/moin/BeginnersGuide/Download Once complete, you will need easy_install to install the Localtunnel client.If you don't have easy_install after you install Python, you can install it with this bootstrap script: $ curl http://peak.telecommunity.com/dist/ez_setup.py | python Once complete, you can install the Localtunnel client using the following command: $ easy_install localtunnel First run with LocalTunnel Once installed, creating a tunnel is as simple as running the following command: $ localtunnel-beta 8082 The parameter after the command: "8000" is the local port we want Localtunnel to forward to. So whatever port your app is running on should replace this value. Each time you run the command you should get output similar to the following: Port 8082 is now accessible from http://fb0322605126.v2.localtunnel.com ... Note: As v2 is still in beta; the command local-tunnel-beta will eventually be installed as just localtunnel. This lets you keep the v1 just in case anything goes wrong with v2 during the beta. Configuring the Connector Now onto Mule! To demonstrate I will use the Twilio Cloud Connector example from Chapter 5. Twilio has an awesome WebHook implementation with great debugging tools. Twilio uses callbacks to tell you about the status of your requests; When you use Twilio to a place a phone call or send an SMS the Twilio API allows you to send a URL where you'll receive information about the phone call once it ends or the status of the outbound SMS message after it's processed. This example uses the Twilio Cloud Connector to send a simple SMS message. The most important thing to note is that the "status-callback-flow-ref" attribute. All connector operations that support callback's will have an optional attribute ending in "-flow-ref". In this case : "status-callback-flow-ref". As the name suggests, this attribute should reference a flow. This value must be a valid flow id from within your configuration. It is this flow that will be used to listen for the callback. Notice that the flow has no inbound endpoint? This is where the magic happens; when Twilio process the SMS message it will send a callback automatically to that flow without you having to define an inbound endpoint. The connector automatically generates an inbound endpoint and sends the auto generated URL to Twilio for you. Customizing the Callback The URL generated for the callback URL is built using 'localhost' as the host, the 'http.port' environment variable or 'localPort' value as the port and the path of the URL is typically just a random generated string or static value. So if I run this locally it would send Twilio my non public address, something like: http://localhost:80/...vv3v3er342fvvn. Each connector that accepts HTTP callbacks will provide you with an optional http-callback-config child element to override these settings. These settings can be set at the connector's config level as follows: Here we have amended the previous example to add the additonal http-callback-config configuration. The configuration takes three additional arguments: domain, localPort and remotePort. These settings will be used to constuct the URL that is passed to the external system. The URL will be the same as the default generated URL of the HTTP inbound-endpoint except that the host is replaced by the 'domain' setting (or its default value) and the port is replaced by the 'remotePort' setting (or its default value). In this case we have used the domain from the URL that Localtunnel generated for us earlier: fb0322605126.v2.localtunnel.com and set the localPort to 8082 as we run the Localtunnel command using port 8082 and the remotePort to 80 as the localtunnel server just runs on port 80. And that's it! If you run this configuration you should start seeing your callback being printed to the console. The same goes for any OAuth connectors too. If your using any OAuth connectors built using the DevKit OAuth modules, you can configure the OAuth callback in a similar fashion. A full Mule/Twilio WebHook project can be found here: https://github.com/ryandcarter/GettingStarted-MuleCloudConnect-OReilly/tree/master/chapter05/twilio-webhooks

As I've shown it in my previous post JBoss Drools are a very useful rules engine. The only problem is that creating the rules in the Rule language might be pretty complicated for a non-technical person. That's why one can provide an easy way for creating business rules - decision tables created in a spreadsheet! In the following example I will show you a really complicated business rule example converted to a decision table in a spreadsheet. As a backend we will have Drools, Camel and Spring. To begin with let us take a look at our imaginary business problem. Let us assume that we are running a business that focuses on selling products (either Medical or Electronic). We are shipping our products to several countries (PL, USA, GER, SWE, UK, ESP) and depending on the country there are different law regulations concerning the buyer's age. In some countries you can buy products when you are younger than in others. What is more depending on the country from which the buyer and the product comes from and on the quantity of products, the buyer might get a discount. As you can see there is a substantial number of conditions needed to be fullfield in this scenario (imagine the number of ifs needed to program this :P ). Another problem would be the business side (as usual). Anybody who has been working on a project knows how fast the requirements are changing. If one entered all the rules in the code he would have to redeploy the software each time the requirements changed. That's why it is a good practice to divide the business logic from the code itself. Anyway, let's go back to our example. To begin with let us take a look at the spreadsheets (before that it is worth taking a look at the JBoss website with precise description of how the decision table should look like): The point of entry of our program is the first spreadsheet that checks if the given user should be granted with the possibility of buying a product (it will be better if you download the spreadsheets and play with them from Too Much Coding's repository at Bitbucket: user_table.xls and product_table.xls, or Github user_table.xls and product_table.xls): user_table.xls (tables worksheet) Once the user has been approved he might get a discount: product_table.xls (tables worksheet) product_table.xls (lists worksheet) As you can see in the images the business problem is quite complex. Each row represents a rule, and each column represents a condition. Do you remember the rules syntax from my recent post? So you would understand the hidden part of the spreadsheet that is right above the first visible row: The rows from 2 to 6 represent some fixed configuration values such as rule set, imports ( you've already seen that in my recent post) and functions. Next in row number 7 you can find the name of the RuleTable. Then in row number 8 you have in our scenario either a CONDITION or an ACTION - so in other words either the LHS or rhe RHS respectively. Row number 9 is both representation of types presented in the condition and the binding to a variable. In row number 10 we have the exact LHS condition. Row number 11 shows the label of columns. From row number 12 we have the rules one by one. You can find the spreadsheets in the sources. Now let's take a look at the code. Let's start with taking a look at the schemas defining the Product and the User. Person.xsd User.xsd Due to the fact that we are using maven we may use a plugin that will convert the XSD into Java classes. part of the pom.xml org.apache.maven.plugins maven-compiler-plugin 2.5.1 org.codehaus.mojo jaxb2-maven-plugin 1.5 xjc xjc pl.grzejszczak.marcin.drools.decisiontable.model ${project.basedir}/src/main/resources/xsd Thanks to this plugin we have our generated by JAXB classes in the pl.grzejszczak.marcin.decisiontable.model package. Now off to the drools-context.xml file where we've defined all the necessary beans as far as Drools are concerned: As you can see in comparison to the application context from the recent post there are some differences. First instead of passing the DRL file as the resource inside the knowledge base we are providing the Decision table (DTABLE). I've decided to pass in two seperate files but you can provide one file with several worksheets and access those worksheets (through the decisiontable-conf element). Also there is an additional element called node. We have to choose an implementation of the Node interface (Execution, Grid...) for the Camel route to work properly as you will see in a couple of seconds in the Spring application context file. applicationContext.xml As you can see in order to access the Drools Camel Component we have to provide the node through which we will access the proper knowledge session. We have defined two routes - the first one ends at the Drools component that accesses the users knowledge session and the other the products knowledge session. We have a ProductService interface implementation called ProductServiceImpl that given an input User and Product objects pass them through the Camel's Producer Template to two Camel routes each ending at the Drools components. The concept behind this product service is that we are first processing the User if he can even buy the software and then we are checking what kind of a discount he would receive. From the service's point of view in fact we are just sending the object out and waiting for the response. Finally having reveived the response we are passing the User and the Product to the Financial Service implementation that will bill the user for the products that he has bought or reject his offer if needed. ProductServiceImpl.java package pl.grzejszczak.marcin.drools.decisiontable.service; import org.apache.camel.CamelContext; import org.slf4j.Logger; import org.slf4j.LoggerFactory; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.stereotype.Component; import pl.grzejszczak.marcin.drools.decisiontable.model.Product; import pl.grzejszczak.marcin.drools.decisiontable.model.User; import static com.google.common.collect.Lists.newArrayList; /** * Created with IntelliJ IDEA. * User: mgrzejszczak * Date: 14.01.13 */ @Component("productServiceImpl") public class ProductServiceImpl implements ProductService { private static final Logger LOGGER = LoggerFactory.getLogger(ProductServiceImpl.class); @Autowired CamelContext camelContext; @Autowired FinancialService financialService; @Override public void runProductLogic(User user, Product product) { LOGGER.debug("Running product logic - first acceptance Route, then discount Route"); camelContext.createProducerTemplate().sendBody("direct:acceptanceRoute", newArrayList(user, product)); camelContext.createProducerTemplate().sendBody("direct:discountRoute", newArrayList(user, product)); financialService.processOrder(user, product); } } Another crucial thing to remember about is that the Camel Drools Component requires the Command object as the input. As you can see, in the body we are sending a list of objects (and these are not Command objects). I did it on purpose since in my opinion it is better not to bind our code to a concrete solution. What if we find out that there is a better solution than Drools? Will we change all the code that we have created or just change the Camel route to point at our new solution? That's why Camel has the TypeConverters. We have our own here as well. First of all let's take a look at the implementation. ProductTypeConverter.java package pl.grzejszczak.marcin.drools.decisiontable.converter; import org.apache.camel.Converter; import org.drools.command.Command; import org.drools.command.CommandFactory; import org.slf4j.Logger; import org.slf4j.LoggerFactory; import pl.grzejszczak.marcin.drools.decisiontable.model.Product; import java.util.List; /** * Created with IntelliJ IDEA. * User: mgrzejszczak * Date: 30.01.13 * Time: 21:42 */ @Converter public class ProductTypeConverter { private static final Logger LOGGER = LoggerFactory.getLogger(ProductTypeConverter.class); @Converter public static Command toCommandFromList(List inputList) { LOGGER.debug("Executing ProductTypeConverter's toCommandFromList method"); return CommandFactory.newInsertElements(inputList); } @Converter public static Command toCommand(Product product) { LOGGER.debug("Executing ProductTypeConverter's toCommand method"); return CommandFactory.newInsert(product); } } There is a good tutorial on TypeConverters on the Camel website - if you needed some more indepth info about it. Anyway, we are annotating our class and the functions used to convert different types into one another. What is important here is that we are showing Camel how to convert a list and a single product to Commands. Due to type erasure this will work regardless of the provided type that is why even though we are giving a list of Product and User, the toCommandFromList function will get executed. In addition to this in order for the type converter to work we have to provide the fully quallified name of our class (FQN) in the /META-INF/services/org/apache/camel/TypeConverter file. TypeConverter pl.grzejszczak.marcin.drools.decisiontable.converter.ProductTypeConverter In order to properly test our functionality one should write quite a few tests that would verify the rules. A pretty good way would be to have input files stored in the test resources folders that are passed to the rule engine and then the result would be compared against the verified output (unfortunately it is rather impossible to make the business side develop such a reference set of outputs). Anyway let's take a look at the unit test that verifies only a few of the rules and the logs that are produced from running those rules: ProductServiceImplTest.java package pl.grzejszczak.marcin.drools.decisiontable.service.drools; import org.apache.commons.lang.builder.ReflectionToStringBuilder; import org.apache.commons.lang.builder.ToStringStyle; import org.junit.Test; import org.junit.runner.RunWith; import org.slf4j.Logger; import org.slf4j.LoggerFactory; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.test.context.ContextConfiguration; import org.springframework.test.context.junit4.SpringJUnit4ClassRunner; import pl.grzejszczak.marcin.drools.decisiontable.model.*; import pl.grzejszczak.marcin.drools.decisiontable.service.ProductService; import static org.junit.Assert.assertEquals; import static org.junit.Assert.assertTrue; /** * Created with IntelliJ IDEA. * User: mgrzejszczak * Date: 03.02.13 * Time: 16:06 */ @RunWith(SpringJUnit4ClassRunner.class) @ContextConfiguration("classpath:applicationContext.xml") public class ProductServiceImplTest { private static final Logger LOGGER = LoggerFactory.getLogger(ProductServiceImplTest.class); @Autowired ProductService objectUnderTest; @Test public void testRunProductLogicUserPlUnderageElectronicCountryPL() throws Exception { int initialPrice = 1000; int userAge = 6; int quantity = 10; User user = createUser("Smith", CountryType.PL, userAge); Product product = createProduct("Electronic", initialPrice, CountryType.PL, ProductType.ELECTRONIC, quantity); printInputs(user, product); objectUnderTest.runProductLogic(user, product); printInputs(user, product); assertTrue(product.getPrice() == initialPrice); assertEquals(DecisionType.REJECTED, user.getDecision()); } @Test public void testRunProductLogicUserPlHighAgeElectronicCountryPLLowQuantity() throws Exception { int initialPrice = 1000; int userAge = 19; int quantity = 1; User user = createUser("Smith", CountryType.PL, userAge); Product product = createProduct("Electronic", initialPrice, CountryType.PL, ProductType.ELECTRONIC, quantity); printInputs(user, product); objectUnderTest.runProductLogic(user, product); printInputs(user, product); assertTrue(product.getPrice() == initialPrice); assertEquals(DecisionType.ACCEPTED, user.getDecision()); } @Test public void testRunProductLogicUserPlHighAgeElectronicCountryPLHighQuantity() throws Exception { int initialPrice = 1000; int userAge = 19; int quantity = 8; User user = createUser("Smith", CountryType.PL, userAge); Product product = createProduct("Electronic", initialPrice, CountryType.PL, ProductType.ELECTRONIC, quantity); printInputs(user, product); objectUnderTest.runProductLogic(user, product); printInputs(user, product); double expectedDiscount = 0.1; assertTrue(product.getPrice() == initialPrice * (1 - expectedDiscount)); assertEquals(DecisionType.ACCEPTED, user.getDecision()); } @Test public void testRunProductLogicUserUsaLowAgeElectronicCountryPLHighQuantity() throws Exception { int initialPrice = 1000; int userAge = 19; int quantity = 8; User user = createUser("Smith", CountryType.USA, userAge); Product product = createProduct("Electronic", initialPrice, CountryType.PL, ProductType.ELECTRONIC, quantity); printInputs(user, product); objectUnderTest.runProductLogic(user, product); printInputs(user, product); assertTrue(product.getPrice() == initialPrice); assertEquals(DecisionType.REJECTED, user.getDecision()); } @Test public void testRunProductLogicUserUsaHighAgeMedicalCountrySWELowQuantity() throws Exception { int initialPrice = 1000; int userAge = 22; int quantity = 4; User user = createUser("Smith", CountryType.USA, userAge); Product product = createProduct("Some name", initialPrice, CountryType.SWE, ProductType.MEDICAL, quantity); printInputs(user, product); objectUnderTest.runProductLogic(user, product); printInputs(user, product); assertTrue(product.getPrice() == initialPrice); assertEquals(DecisionType.ACCEPTED, user.getDecision()); } @Test public void testRunProductLogicUserUsaHighAgeMedicalCountrySWEHighQuantity() throws Exception { int initialPrice = 1000; int userAge = 22; int quantity = 8; User user = createUser("Smith", CountryType.USA, userAge); Product product = createProduct("Some name", initialPrice, CountryType.SWE, ProductType.MEDICAL, quantity); printInputs(user, product); objectUnderTest.runProductLogic(user, product); printInputs(user, product); double expectedDiscount = 0.25; assertTrue(product.getPrice() == initialPrice * (1 - expectedDiscount)); assertEquals(DecisionType.ACCEPTED, user.getDecision()); } private void printInputs(User user, Product product) { LOGGER.debug(ReflectionToStringBuilder.reflectionToString(user, ToStringStyle.MULTI_LINE_STYLE)); LOGGER.debug(ReflectionToStringBuilder.reflectionToString(product, ToStringStyle.MULTI_LINE_STYLE)); } private User createUser(String name, CountryType countryType, int userAge){ User user = new User(); user.setUserName(name); user.setUserCountry(countryType); user.setUserAge(userAge); return user; } private Product createProduct(String name, double price, CountryType countryOfOrigin, ProductType productType, int quantity){ Product product = new Product(); product.setPrice(price); product.setCountryOfOrigin(countryOfOrigin); product.setName(name); product.setType(productType); product.setQuantity(quantity); return product; } } Of course the log.debugs in the tests are totally redundant but I wanted you to quickly see that the rules are operational :) Sorry for the length of the logs but I wrote a few tests to show different combinations of rules (in fact it's better too have too many logs than the other way round :) ) pl.grzejszczak.marcin.drools.decisiontable.service.drools.ProductServiceImplTest:150 pl.grzejszczak.marcin.drools.decisiontable.model.User@1d48043[ userName=Smith userAge=6 userCountry=PL decision= decisionDescription= ] pl.grzejszczak.marcin.drools.decisiontable.service.drools.ProductServiceImplTest:151 pl.grzejszczak.marcin.drools.decisiontable.model.Product@1e8f2a0[ name=Electronic type=ELECTRONIC price=1000.0 countryOfOrigin=PL additionalInfo= quantity=10 ] pl.grzejszczak.marcin.drools.decisiontable.service.ProductServiceImpl:31 Running product logic - first acceptance Route, then discount Route pl.grzejszczak.marcin.drools.decisiontable.converter.ProductTypeConverter:25 Executing ProductTypeConverter's toCommandFromList method pl.grzejszczak.marcin.drools.decisiontable.service.ProductService:8 Sorry, according to your age (< 18) and country (PL) you can't buy this product pl.grzejszczak.marcin.drools.decisiontable.converter.ProductTypeConverter:25 Executing ProductTypeConverter's toCommandFromList method pl.grzejszczak.marcin.drools.decisiontable.service.FinancialServiceImpl:29 Sorry, user has been rejected... pl.grzejszczak.marcin.drools.decisiontable.service.drools.ProductServiceImplTest:150 pl.grzejszczak.marcin.drools.decisiontable.model.User@1d48043[ userName=Smith userAge=6 userCountry=PL decision=REJECTED decisionDescription=Sorry, according to your age (< 18) and country (PL) you can't buy this product ] pl.grzejszczak.marcin.drools.decisiontable.service.drools.ProductServiceImplTest:151 pl.grzejszczak.marcin.drools.decisiontable.model.Product@1e8f2a0[ name=Electronic type=ELECTRONIC price=1000.0 countryOfOrigin=PL additionalInfo= quantity=10 ] pl.grzejszczak.marcin.drools.decisiontable.service.drools.ProductServiceImplTest:150 pl.grzejszczak.marcin.drools.decisiontable.model.User@b28f30[ userName=Smith userAge=19 userCountry=PL decision= decisionDescription= ] pl.grzejszczak.marcin.drools.decisiontable.service.drools.ProductServiceImplTest:151 pl.grzejszczak.marcin.drools.decisiontable.model.Product@d6a0e0[ name=Electronic type=ELECTRONIC price=1000.0 countryOfOrigin=PL additionalInfo= quantity=1 ] pl.grzejszczak.marcin.drools.decisiontable.service.ProductServiceImpl:31 Running product logic - first acceptance Route, then discount Route pl.grzejszczak.marcin.drools.decisiontable.converter.ProductTypeConverter:25 Executing ProductTypeConverter's toCommandFromList method pl.grzejszczak.marcin.drools.decisiontable.service.ProductService:8 Congratulations, you have successfully bought the product pl.grzejszczak.marcin.drools.decisiontable.converter.ProductTypeConverter:25 Executing ProductTypeConverter's toCommandFromList method pl.grzejszczak.marcin.drools.decisiontable.service.ProductService:8 Sorry, no discount will be granted. pl.grzejszczak.marcin.drools.decisiontable.service.FinancialServiceImpl:25 User has been approved - processing the order... pl.grzejszczak.marcin.drools.decisiontable.service.drools.ProductServiceImplTest:150 pl.grzejszczak.marcin.drools.decisiontable.model.User@b28f30[ userName=Smith userAge=19 userCountry=PL decision=ACCEPTED decisionDescription=Congratulations, you have successfully bought the product ] pl.grzejszczak.marcin.drools.decisiontable.service.drools.ProductServiceImplTest:151 pl.grzejszczak.marcin.drools.decisiontable.model.Product@d6a0e0[ name=Electronic type=ELECTRONIC price=1000.0 countryOfOrigin=PL additionalInfo=Sorry, no discount will be granted. quantity=1 ] pl.grzejszczak.marcin.drools.decisiontable.service.drools.ProductServiceImplTest:150 pl.grzejszczak.marcin.drools.decisiontable.model.User@14510ac[ userName=Smith userAge=19 userCountry=PL decision= decisionDescription= ] pl.grzejszczak.marcin.drools.decisiontable.service.drools.ProductServiceImplTest:151 pl.grzejszczak.marcin.drools.decisiontable.model.Product@1499616[ name=Electronic type=ELECTRONIC price=1000.0 countryOfOrigin=PL additionalInfo= quantity=8 ] pl.grzejszczak.marcin.drools.decisiontable.service.ProductServiceImpl:31 Running product logic - first acceptance Route, then discount Route pl.grzejszczak.marcin.drools.decisiontable.converter.ProductTypeConverter:25 Executing ProductTypeConverter's toCommandFromList method pl.grzejszczak.marcin.drools.decisiontable.service.ProductService:8 Congratulations, you have successfully bought the product pl.grzejszczak.marcin.drools.decisiontable.converter.ProductTypeConverter:25 Executing ProductTypeConverter's toCommandFromList method pl.grzejszczak.marcin.drools.decisiontable.service.ProductService:8 Congratulations - you've been granted a 10% discount! pl.grzejszczak.marcin.drools.decisiontable.service.FinancialServiceImpl:25 User has been approved - processing the order... pl.grzejszczak.marcin.drools.decisiontable.service.drools.ProductServiceImplTest:150 pl.grzejszczak.marcin.drools.decisiontable.model.User@14510ac[ userName=Smith userAge=19 userCountry=PL decision=ACCEPTED decisionDescription=Congratulations, you have successfully bought the product ] pl.grzejszczak.marcin.drools.decisiontable.service.drools.ProductServiceImplTest:151 pl.grzejszczak.marcin.drools.decisiontable.model.Product@1499616[ name=Electronic type=ELECTRONIC price=900.0 countryOfOrigin=PL additionalInfo=Congratulations - you've been granted a 10% discount! quantity=8 ] pl.grzejszczak.marcin.drools.decisiontable.service.drools.ProductServiceImplTest:150 pl.grzejszczak.marcin.drools.decisiontable.model.User@17667bd[ userName=Smith userAge=19 userCountry=USA decision= decisionDescription= ] pl.grzejszczak.marcin.drools.decisiontable.service.drools.ProductServiceImplTest:151 pl.grzejszczak.marcin.drools.decisiontable.model.Product@ad9f5d[ name=Electronic type=ELECTRONIC price=1000.0 countryOfOrigin=PL additionalInfo= quantity=8 ] pl.grzejszczak.marcin.drools.decisiontable.service.ProductServiceImpl:31 Running product logic - first acceptance Route, then discount Route pl.grzejszczak.marcin.drools.decisiontable.converter.ProductTypeConverter:25 Executing ProductTypeConverter's toCommandFromList method pl.grzejszczak.marcin.drools.decisiontable.service.ProductService:8 Sorry, according to your age (< 18) and country (USA) you can't buy this product pl.grzejszczak.marcin.drools.decisiontable.converter.ProductTypeConverter:25 Executing ProductTypeConverter's toCommandFromList method pl.grzejszczak.marcin.drools.decisiontable.service.FinancialServiceImpl:29 Sorry, user has been rejected... pl.grzejszczak.marcin.drools.decisiontable.service.drools.ProductServiceImplTest:150 pl.grzejszczak.marcin.drools.decisiontable.model.User@17667bd[ userName=Smith userAge=19 userCountry=USA decision=REJECTED decisionDescription=Sorry, according to your age (< 18) and country (USA) you can't buy this product ] pl.grzejszczak.marcin.drools.decisiontable.service.drools.ProductServiceImplTest:151 pl.grzejszczak.marcin.drools.decisiontable.model.Product@ad9f5d[ name=Electronic type=ELECTRONIC price=1000.0 countryOfOrigin=PL additionalInfo= quantity=8 ] pl.grzejszczak.marcin.drools.decisiontable.service.drools.ProductServiceImplTest:150 pl.grzejszczak.marcin.drools.decisiontable.model.User@9ff588[ userName=Smith userAge=22 userCountry=USA decision= decisionDescription= ] pl.grzejszczak.marcin.drools.decisiontable.service.drools.ProductServiceImplTest:151 pl.grzejszczak.marcin.drools.decisiontable.model.Product@1b0d2d0[ name=Some name type=MEDICAL price=1000.0 countryOfOrigin=SWE additionalInfo= quantity=4 ] pl.grzejszczak.marcin.drools.decisiontable.service.ProductServiceImpl:31 Running product logic - first acceptance Route, then discount Route pl.grzejszczak.marcin.drools.decisiontable.converter.ProductTypeConverter:25 Executing ProductTypeConverter's toCommandFromList method pl.grzejszczak.marcin.drools.decisiontable.service.ProductService:8 Congratulations, you have successfully bought the product pl.grzejszczak.marcin.drools.decisiontable.converter.ProductTypeConverter:25 Executing ProductTypeConverter's toCommandFromList method pl.grzejszczak.marcin.drools.decisiontable.service.FinancialServiceImpl:25 User has been approved - processing the order... pl.grzejszczak.marcin.drools.decisiontable.service.drools.ProductServiceImplTest:150 pl.grzejszczak.marcin.drools.decisiontable.model.User@9ff588[ userName=Smith userAge=22 userCountry=USA decision=ACCEPTED decisionDescription=Congratulations, you have successfully bought the product ] pl.grzejszczak.marcin.drools.decisiontable.service.drools.ProductServiceImplTest:151 pl.grzejszczak.marcin.drools.decisiontable.model.Product@1b0d2d0[ name=Some name type=MEDICAL price=1000.0 countryOfOrigin=SWE additionalInfo= quantity=4 ] pl.grzejszczak.marcin.drools.decisiontable.service.drools.ProductServiceImplTest:150 pl.grzejszczak.marcin.drools.decisiontable.model.User@1b27882[ userName=Smith userAge=22 userCountry=USA decision= decisionDescription= ] pl.grzejszczak.marcin.drools.decisiontable.service.drools.ProductServiceImplTest:151 pl.grzejszczak.marcin.drools.decisiontable.model.Product@5b84b[ name=Some name type=MEDICAL price=1000.0 countryOfOrigin=SWE additionalInfo= quantity=8 ] pl.grzejszczak.marcin.drools.decisiontable.service.ProductServiceImpl:31 Running product logic - first acceptance Route, then discount Route pl.grzejszczak.marcin.drools.decisiontable.converter.ProductTypeConverter:25 Executing ProductTypeConverter's toCommandFromList method pl.grzejszczak.marcin.drools.decisiontable.service.ProductService:8 Congratulations, you have successfully bought the product pl.grzejszczak.marcin.drools.decisiontable.converter.ProductTypeConverter:25 Executing ProductTypeConverter's toCommandFromList method pl.grzejszczak.marcin.drools.decisiontable.service.ProductService:8 Congratulations, you are granted a discount pl.grzejszczak.marcin.drools.decisiontable.service.FinancialServiceImpl:25 User has been approved - processing the order... pl.grzejszczak.marcin.drools.decisiontable.service.drools.ProductServiceImplTest:150 pl.grzejszczak.marcin.drools.decisiontable.model.User@1b27882[ userName=Smith userAge=22 userCountry=USA decision=ACCEPTED decisionDescription=Congratulations, you have successfully bought the product ] pl.grzejszczak.marcin.drools.decisiontable.service.drools.ProductServiceImplTest:151 pl.grzejszczak.marcin.drools.decisiontable.model.Product@5b84b[ name=Some name type=MEDICAL price=750.0 countryOfOrigin=SWE additionalInfo=Congratulations, you are granted a discount quantity=8 ] In this post I've presented how you can push some of your developing work to your BA by giving him a tool which he can be able to work woth - the Decision Tables in a spreadsheet. What is more now you will now how to integrate Drools with Camel. Hopefully you will see how you can simplify (thus minimize the cost of implementing and supporting) the implementation of business rules bearing in mind how prone to changes they are. I hope that this example will even better illustrate how difficult it would be to implement all the business rules in Java than in the previous post about Drools. If you have any experience with Drools in terms of decision tables, integration with Spring and Camel please feel free to leave a comment here or on my blog - let's have a discussion on that :) All the code is available at Too Much Coding repository at Bitbucket and GitHub.

Curator's Note: This article was co-authored by Andrzej Jarzyna. At 3scale we find Amazon to be a fantastic platform for running APIs due to the complete control you have on the application stack. For people new to AWS the learning curve is quite steep. So we put together our best practices into this short tutorial. Besides Amazon EC2 we will use the Ruby Grape gem to create the API interface and an Nginx proxy to handle access control. Best of all everything in this tutorial is completely FREE! For the purpose of this tutorial you will need a running API based on Ruby and Thin server. If you don’t have one you can simply clone an example repo as described below (in the “Deploying the Application” section). If you are interested in the background of this example (Sentiment API), you can see a couple of previous guides which 3scale has published. Here we use version_1 of the API(‘API up and running in 10 minutes‘) with some extra sentiment analysis functionality (this part is covered in the second tutorial of the Sentiment API tutorial). Now we will start the creation and configuration of the Amazon EC2 instance. If you already have an EC2 instance (micro or not), you can jump to the next step -> Preparing Instance for Deployment. Creating and configuring EC2 Instance Let’s start by signing up for the Amazon Elastic Compute Cloud (Amazon EC2). For our needs the free tier http://aws.amazon.com/free/ is enough, covering all the basic needs. Once the account is created go to the EC2 dashboard under your AWS Management Console and click on the Launch Instance button. That will transfer you to a popup window where you will continue the process: Choose the classic wizard Choose an AMI (Ubuntu Server 12.04.1 LTS 32bit, T1micro instance) leaving all the other settings for Instance Details as default Create a keypair and download it – this will be the key which you will use to make an ssh connection to the server, it’s VERY IMPORTANT! Add inbound rules for the firewall with source always 0.0.0.0/0 (HTTP, HTTPS, ALL ICMP, TCP port 3000 used by the Ruby thin server) Preparing Instance for Deployment Now, as we have the instance created and running, we can directly connect there from our console (Windows users from PuTTY). Right click on your instance, connect and choose Connect with a standalone SSH Client. Follow the steps and change the username to ubuntu (instead of root) in the given example. After executing this step you are connected to your instance. We will have to install new packages. Some of them require root credentials, so you will have to set a new root password: sudo passwd root. Then login as root: su root. Now with root credentials execute: sudo apt-get update and switch back to your normal user with exit command and install all the required packages: install some libraries which will be required by rvm, ruby and git: sudo apt-get install build-essential git zlib1g-dev libssl-dev libreadline-gplv2-dev imagemagick libxml2-dev libxslt1-dev openssl libreadline6 libreadline6-dev zlib1g libyaml-dev libxslt-dev autoconf libc6-dev ncurses-dev automake libtool bison libpq-dev libpq5 libeditline-dev install git (on Linux rather than from Source): http://www.git-scm.com/book/en/Getting-Started-Installing-Git install rvm: https://rvm.io/rvm/install/ install ruby rvm install 1.9.3 rvm use 1.9.3 --default Deploying the Application Our sample Sentiment API is located on Github. Try cloning the repository: git clone [email protected]:jerzyn/api-demo.git you can once again review the code and tutorial on creating and deploying this app here: http://www.3scale.net/2012/06/the-10-minute-api-up-running-3scale-grape-heroku-api-10-minutes/ and here http://www.3scale.net/2012/07/how-to-out-of-the-box-api-analytics/ note the changes (we are using only v1, as authentication will go through the proxy). Now you can deploy the app by issuing: bundle install. Now you can start the thin server: thin start. To access the API directly (i.e. without any security or access control) access: your-public-dns:3000/v1/words/awesome.json (you can find your-public-dns in the AWS EC2 Dashboard->Instances in the details window of your instance) For the Nginx integration you will have to create an elastic IP address. Inside the AWS EC2 dashboard create an elastic IP in the same region as your instance and associate that IP to it (you won’t have to pay anything for the elastic IP as long as it is associated with your instance in the same region). OPTIONAL: If you want to assign a custom domain to your amazon instance you will have to do one thing: add an A record to the DNS record of your domain mapping the domain to the elastic IP address you have previously created. Your domain provider should either give you some way to set the A record (the IPv4 address), or it will give you a way to edit the nameservers of your domain. If they do not allow you to set the A record directly, find a DNS management service, register your domain as a zone there and the service will give you the nameservers to enter in the admin panel of your domain provider. You can then add the A record for the domain. Some possible DNS management services include ZoneEdit (basic, free), Amazon route 53, etc. At this point you API is open to the world. This is good and bad – great that you are sharing, but bad in the sense that without rate limits a few apps could kill the resources of your server, and you have no insight into who is using your API and how it is being used. The solution is to add some management for your API… Enabling API Management with 3scale Rather than reinvent the wheel and implement rate limits, access controls and analytics from scratch we will leverage the handy 3scale API Management service. Get your free 3scale account, activate and log-in to the new instance through the provided links. The first time you log-in you can choose the option for some sample data to be created, so you will have some API keys to use later. Next you would probably like to go through the tour to get a glimpse on the system functionality (optional) and then start with the implementation. To get some instant results we will start with the sandbox proxy which can be used while in development. Then we will also configure an Nginx proxy which can scale up for full production deployments. There is some documentation on the configuration of the API proxy at 3scale: https://support.3scale.net/howtos/api-configuration/nginx-proxy and for more advanced configuration options here: https://support.3scale.net/howtos/api-configuration/nginx-proxy-advanced Once you sign into your 3scale account, Launch your API on the main Dashboard screen or Go to API->Select the service (API)->Integration in the sidebar->Proxy Set the address of of your API backend – this has to be the Elastic IP address unless the custom domain has been set, including http protocol and port 3000. Now you can save and turn on the sandbox proxy to test your API by hitting the sandbox endpoint (after creating some app credentials in 3scale): http://sandbox-endpoint/v1/words/awesome.json?app_id=APP_ID&app_key=APP_KEY where, APP_ID and APP_KEY are id and key of one of the sample applications which you created when you first logged into your 3scale account (if you missed that step just create a developer account and an application within that account). Try it without app credentials, next with incorrect credentials, and then once authenticated within and over any rate limits that you have defined. Only once it is working to your satisfaction do you need to download the config files for Nginx. Note: any time you have errors check whether you can access the API directly: your-public-dns:3000/v1/words/awesome.json. If that is not available, then you need to check if the AWS instance is running and if the Thin Server is running on the instance. Implement an Nginx Proxy for Access Control In order to streamline this step we recommend that you install the fantastic OpenResty web application that is basically a bundle of the standard Nginx core with almost all the necessary 3rd party Nginx modules built-in. Install dependencies: sudo apt-get install libreadline-dev libncurses5-dev libpcre3-dev perl Compile and install Nginx: cd ~ sudo wget http://agentzh.org/misc/nginx/ngx_openresty-1.2.3.8.tar.gz sudo tar -zxvf ngx_openresty-1.2.3.8.tar.gz cd ngx_openresty-1.2.3.8/ ./configure --prefix=/opt/openresty --with-luajit --with-http_iconv_module -j2 make sudo make install In the config file make the following changes: edit the .conf file from nginx download in line 28, which is preceded by info to change your server name put the correct domain (of your Elastic IP or custom domain name) in line 78 change the path to the .lua file, downloaded together with the .conf file. We are almost finished! Our last step is to start the NGINX proxy and put some traffic through it. If it is not running yet (remember, that thin server has to be started first), please go to your EC2 instance terminal (the one you were connecting through ssh before) and start it now: sudo /opt/openresty/nginx/sbin/nginx -p /opt/openresty/nginx/ -c /opt/openresty/nginx/conf/YOUR-CONFIG-FILE.conf The last step will be verifying that the traffic goes through with a proper authorization. To do that, access: http://your-public-dns/v1/words/awesome.json?app_id=APP_ID&app_key=APP_KEY where, APP_ID and APP_KEY are key and id of the application you want to access through the API call. Once everything is confirmed as working correctly, you will want to block public access to the API backend on port 3000, which bypasses any access controls. If encounter some problems with the Nginx configuration or need a more detailed guide, I encourage you to check the 3scale guide on configuring Nginx proxy: https://support.3scale.net/howtos/api-configuration/nginx-proxy. You can go completely wild with customization of your API gateway. If you want to dive more into the 3scale system configuration (like usage and monitoring of your API traffic) feel encouraged to browse our Quickstart guides and HowTo’s.

By default, Spring beans are scoped singleton, meaning there’s only one instance for the whole application context. For most applications, this is a sensible default; then sometimes, not so much. This may be the case when using a custom scope, which is the case, on the product I’m currently working on. I’m not at liberty to discuss the details further: suffice to say that it is very painful to configure each and every needed bean with this custom scope. Since being lazy in a smart way is at the core of developer work, I decided to search for a way to ease my burden and found it in the BeanFactoryPostProcessor class. It only has a single method - postProcessBeanFactory(), but it gives access to the bean factory itself (which is at the root of the various application context classes). From this point on, the code is trivial even with no prior experience of the API: public class PrototypeScopedBeanFactoryPostProcessor implements BeanFactoryPostProcessor { @Override public void postProcessBeanFactory(ConfigurableListableBeanFactory factory) throws BeansException { for (String beanName : factory.getBeanDefinitionNames()) { BeanDefinition beanDef = factory.getBeanDefinition(beanName); String explicitScope = beanDef.getScope(); if ("".equals(explicitScope)) { beanDef.setScope("prototype"); } } } } The final touch is to register the post-processor in the context . This is achieved by treating it as a simple anonymous bean: Now, every bean which scope is not explicitly set will be scoped prototype. Sources for this article can be found attached in Eclipse/Maven format.

Groovy 2.0 brought us extension modules. An extension module is a JAR file with classes that provide extra methods to existing other classes like in the JDK or third-party libraries. Groovy uses this mechanism to add for example extra methods to the File class. We can implement our own extension module to add new extension methods to existing classes. Once we have written the module we can add it to the classpath of our code or application and all the new methods are immediately available. We define the new extension methods in helper classes, which are part of the module. We can create instance and static extension methods, but we need a separate helper class for each type of extension method. We cannot mix static and instance extension methods in one helper class. First we create a very simple class with an extension method for the String class. The first argument of the extension method defines the type or class we want the method to be added to. The following code shows the method likeAPirate. The extension method needs to be public and static even though we are creating an instance extension method. // File: src/main/groovy/com/mrhaki/groovy/PirateExtension.groovy package com.mrhaki.groovy class PirateExtension { static String likeAPirate(final String self) { // List of pirate language translations. def translations = [ ["hello", "ahoy"], ["Hi", "Yo-ho-ho"], ['are', 'be'], ['am', 'be'], ['is', 'be'], ['the', "th'"], ['you', 'ye'], ['your', 'yer'], ['of', "o'"] ] // Translate the original String to a // pirate language String. String result = self translations.each { translate -> result = result.replaceAll(translate[0], translate[1]) } result } } Next we need to create an extension module descriptor file. In this file we define the name of the helper class, so Groovy will know how to use it. The descriptor file needs to be placed in the META-INF/services directory of our module archive or classpath. The name of the file is org.codehaus.groovy.runtime.ExtensionModule. In the file we define the name of our module, version and the name of the helper class. The name of the helper class is defined with the property extensionClasses: # File: src/main/resources/META-INF/services/org.codehaus.groovy.runtime.ExtensionModule moduleName = pirate-module moduleVersion = 1.0 extensionClasses = com.mrhaki.groovy.PirateExtension Now are extension module is ready. The easiest way to distribute the module is by packaging the code and descriptor file in a JAR file and put it in a artifact repository manager. Other developers can then use build tools like Gradle or Maven to include the extension module in their projects and applications. If we use Gradle to create a JAR file we only needs this small build script: / File: build.gradle apply plugin: 'groovy' repositories.mavenCentral() dependencies { // Since Gradle 1.4 we don't use the groovy configuration // to define dependencies. We can simply use the // compile and testCompile configurations. compile 'org.codehaus.groovy:groovy-all:2.0.6' } Now we can invoke $ gradle build and we got ourselves an extension module. Let's add a test for our new extension method. Because we use Gradle the test classpath already will contain our extension module helper class and descriptor file. In our test we can simply invoke the method and test the results. We are going to use Spock to write a simple specification: // File: src/test/groovy/com/mrhaki/groovy/PirateExtensionSpec.groovy package com.mrhaki.groovy import spock.lang.Specification class PirateExtensionSpec extends Specification { def "likeAPirate method should work as instance method on a String value"() { given: final String originalText = "Hi, Groovy is the greatest language of the JVM." expect: originalText.likeAPirate() == "Yo-ho-ho, Groovy be th' greatest language o' th' JVM." } } We add the dependency to Spock in our Gradle build file: / File: build.gradle apply plugin: 'groovy' repositories.mavenCentral() dependencies { // Since Gradle 1.4 we don't use the groovy configuration // to define dependencies. We can simply use the // compile and testCompile configurations. compile 'org.codehaus.groovy:groovy-all:2.0.6' testCompile 'org.spockframework:spock-core:0.7-groovy-2.0' } We can run $ gradle test to run the Spock specification and test our new extension method. To add a static method to an existing class we need to add an extra helper class to our extension module and an extra property to our descriptor file to register the helper class. The first argument of the extension method define the type we want to add a static method to. In the following helper class we add the extension method talkLikeAPirate() to the String class. / File: src/main/groovy/com/mrhaki/groovy/PirateStaticExtension.groovy package com.mrhaki.groovy class PirateStaticExtension { static String talkLikeAPirate(final String type) { "Arr, me hearty," } We change the descriptor file and add the staticExtensionClasses property: # File: src/main/resources/META-INF/services/org.codehaus.groovy.runtime.ExtensionModule moduleName = pirate-module moduleVersion = 1.0 extensionClasses = com.mrhaki.groovy.PirateExtension staticExtensionClasses = com.mrhaki.groovy.PirateStaticExtension In our Spock specification we add an extra test for our new static method talkLikeAPirate() on the String class: // File: src/test/groovy/com/mrhaki/groovy/PirateExtensionSpec.groovy package com.mrhaki.groovy import spock.lang.Specification class PirateExtensionSpec extends Specification { def "likeAPirate method should work as instance method on a String value"() { given: final String originalText = "Hi, Groovy is the greatest language of the JVM." expect: originalText.likeAPirate() == "Yo-ho-ho, Groovy be th' greatest language o' th' JVM." } def "talkLikeAPirate method should work as static method on String class"() { expect: "Arr, me hearty, Groovy rocks!" == String.talkLikeAPirate() + " Groovy rocks!" } } Written with Groovy 2.1

I am working on a Spring MVC app that demonstrates all of the different MongoDB Java APIs. Some Links http://code.google.com/p/morphia/wiki/QuickStart http://www.mongodb.org/display/DOCS/Java+Tutorial http://jongo.org/#updating https://github.com/hibernate/hibernate-ogm https://openshift.redhat.com/community/blogs/configuring-hibernateogm-for-your-jboss-app-using-mongodb-on-openshift-paas http://www.hibernate.org/subprojects/ogm.html https://github.com/impetus-opensource/Kundera/wiki https://github.com/impetus-opensource/Kundera/wiki/Getting-Started-in-5-minutes http://blog.fisharefriends.us/morphia-vs-spring-data-mongodb/ http://www.ibm.com/developerworks/java/library/j-morphia/index.html Maven POM Settings For Various Drivers morphia Morphia http://morphia.googlecode.com/svn/mavenrepo/ default sonatype-nexus Kundera Public Repository https://oss.sonatype.org/content/repositories/releases true false kundera-missing Kundera Public Missing Resources Repository http://kundera.googlecode.com/svn/maven2/maven-missing-resources true true com.google.code.morphia morphia 0.99 org.hibernate.ogm hibernate-ogm-core 4.0.0-SNAPSHOT provided org.mongodb mongo-java-driver 2.10.1 org.springframework.data spring-data-mongodb 1.0.4.RELEASE Hibernate OGM for MongoDB https://community.jboss.org/wiki/PortingSeamHotelBookingExampleToOGM https://github.com/ajf8/seam-booking-ogm https://openshift.redhat.com/community/blogs/configuring-hibernateogm-for-your-jboss-app-using-mongodb-on-openshift-paas https://github.com/openshift/openshift-ogm-quickstart Kundera (JPA for MongoDB) https://github.com/impetus-opensource/Kundera-Examples/wiki/Using-Kundera-with-Spring https://github.com/impetus-opensource/Kundera https://github.com/impetus-opensource/kundera-mongo-performance https://github.com/impetus-opensource/Kundera-Examples https://github.com/impetus-opensource/Kundera/wiki/Sample-Codes-and-Examples https://github.com/impetus-opensource/Kundera-Examples/wiki/Twitter https://dzone.com/articles/sqlifying-nosql-–-are-orm https://github.com/xamry/twitample https://github.com/impetus-opensource/Kundera-Examples/wiki/Cross-datastore-persistence-using-Kundera http://prabhubuzz.wordpress.com/2012/05/25/mongodb-cassandra-jpa-service-using-kundera/ http://gora.apache.org/ http://xamry.wordpress.com/2011/05/02/working-with-mongodb-using-kundera/ https://github.com/impetus-opensource/Kundera/wiki/Getting-Started-in-5-minutes https://github.com/impetus-opensource/Kundera/wiki/Concepts

This morning Dave Richeson posted a humorous fake proof that depends on the famous approximation 22/7 for pi. It occurred to me that nearly everyone knows a decent rational approximation to pi. Some people may know more. But hardly anyone, myself included, knows a decent rational approximation for e. Another approximation for pi is 355/113. I like this approximation because it’s easy to remember: take the sequence 113355, split it in the middle, and make it into a fraction. It’s accurate to six decimal places, which is sufficient for most practical applications. The approximations 22/7 and 355/113 are part of the sequence of approximations coming from the continued fraction approximation for pi. So to come up with rational approximations for e, I turned to its continued fraction representation. The best analog of the approximation 22/7 for pi may be the approximation 19/7 for e. Obviously the denominators are the same, and the accuracy of the two approximations is roughly comparable. Here’s how you can make your own rational approximations for e. Find the coefficients in the continued fraction for e, for example here. You can turn this into a sequence of approximations by using the following Python code: from __future__ import division from math import e e_frac = [2,1,2,1,1,4,1,1,6,1,1,8] def display(n, d, exact): print n, d, n/d, n/d - exact def approx(a, exact): # initialize the recurrence n0 = a[0] d0 = 1 n1 = a[0]*a[1] + 1 d1 = a[1] display(n0, d0, exact) display(n1, d1, exact) for x in a[2:]: n = x*n1 + n0 # numerator d = x*d1 + d0 # denominator display(n, d, exact) n1, n0 = n, n1 d1, d0 = d, d1 approx(e_frac, e) This will print the numerator, denominator, value, and error for each approximation. You could include more terms in the continued fraction for e if you’d like. Here are some of the results: 19/7, 87/32, 106/39, etc. Unfortunately it doesn’t look like there are any approximations as memorable as 355/113 for pi. You could also use the code to create rational approximations to other numbers if you’d like. For example, you can find the continued fraction expansion for pi here and use the code above to find rational approximations for pi.

Groovy 2.1 adds the method directorySize() to File objects. If the File object is a directory then the total size of all files is calculated. Notice this method will go recursively through all subdirectories so it might take some time before the method returns. If we invoke the method on a File object that is not a directory an IllegalArgumentException is thrown. def sampleDir = new File('sample') def sampleDirSize = sampleDir.directorySize() println sampleDirSize // Outputs size in bytes, eg. 130615981 Using Groovy from the command-line we can easily get the directory size like this: $ groovy -e "println new File('.').directorySize()" Written with Groovy 2.1

In this post I'll document the simple configuration needed by ActiveMQ to configure the JDBC persistence adapter and setting up MySQL as the persistent storage. With this type of configuration you can also configure a Master/Slave broker setup by having more than one broker connect to the same database instance. List of Binaries used for this Example mysql-5.5.20-osx10.6-x86_64 mysql-connector-java-5.1.18-bin.jar apache-activemq-5.5.1-fuse-01-13 Configuring MySQL Download and install MySQL. Note for OS X users: The dmg provides a simple install that contains a Startup Item package which will configure MySQL to start automatically after each reboot as well as a Preference Pane plugin which will get added to the Settings panel to allow you to start/stop and configure autostart of MySQL. Once you have you have MySQL installed and properly configured, you will need to start the MySQL Monitor to create a user and database. macbookpro-251a:bin jsherman$ ./mysql -u root Welcome to the MySQL monitor. Commands end with ; or \g. Your MySQL connection id is 29 Server version: 5.5.20 MySQL Community Server (GPL) Copyright (c) 2000, 2011, Oracle and/or its affiliates. All rights reserved. Oracle is a registered trademark of Oracle Corporation and/or its affiliates. Other names may be trademarks of their respective owners. Type 'help;' or '\h' for help. Type '\c' to clear the current input statement. mysql> Then create the database for ActiveMQ mysql> CREATE DATABASE activemq; Then create a user and grant them privileges for the database mysql> CREATE USER 'activemq'@'%'localhost' IDENTIFIED BY 'activemq'; mysql> GRANT ALL ON activemq.* TO 'activemq'@'localhost'; mysql> exit Now log back into the MySQL Monitor and access the activemq database with the activemq user to make sure everything is okay macbookpro-251a:bin jsherman$ ./mysql -u activemq -p activemq Enter password: Reading table information for completion of table and column names You can turn off this feature to get a quicker startup with -A Welcome to the MySQL monitor. Commands end with ; or \g. Your MySQL connection id is 28 Server version: 5.5.20 MySQL Community Server (GPL) Copyright (c) 2000, 2011, Oracle and/or its affiliates. All rights reserved. Oracle is a registered trademark of Oracle Corporation and/or its affiliates. Other names may be trademarks of their respective owners. Type 'help;' or '\h' for help. Type '\c' to clear the current input statement. mysql>exit ActiveMQ Broker Configuration Download the latest FuseSource distribution of ActiveMQ. In the broker's configuration file, activemq.xml, add the following persistence adapter to configure a JDBC connection to MySQL. Then, just after the ending broker element () add the following bean Copy the MySQL diver to the ActiveMQ lib directory, mysql-connector-java-5.1.18-bin.jar was used in this example. Now start your broker, you should see the following output if running from the console INFO | Using Persistence Adapter: JDBCPersistenceAdapter(org.apache.commons.dbcp.BasicDataSource@303bc1a1) INFO | Database adapter driver override recognized for : [mysql-ab_jdbc_driver] - adapter: class org.apache.activemq.store.jdbc.adapter.MySqlJDBCAdapter INFO | Database lock driver override not found for : [mysql-ab_jdbc_driver]. Will use default implementation. INFO | Attempting to acquire the exclusive lock to become the Master broker INFO | Becoming the master on dataSource: org.apache.commons.dbcp.BasicDataSource@303bc1a1 INFO | ActiveMQ 5.5.1-fuse-01-13 JMS Message Broker (jdbcBroker1) is starting Now you can check your database in MySQL and see that ActiveMQ has created the required tables. mysql> USE activemq; SHOW TABLES; +--------------------+ | Tables_in_activemq | +--------------------+ | ACTIVEMQ_ACKS | | ACTIVEMQ_LOCK | | activemq_msgs | +--------------------+ 3 rows in set (0.00 sec) mysql> If you configure multiple brokers to use this same database instance in the jdbcPersistenceAdapter element then these brokers will attempt to acquire a lock, if they are unable to get a database lock the will wait until the lock becomes available. This can be seen by starting a second broker using the above JDBC persistence configuration. INFO | PListStore:activemq-data/jdbcBroker/tmp_storage started INFO | Using Persistence Adapter: JDBCPersistenceAdapter(org.apache.commons.dbcp.BasicDataSource@78979f67) INFO | Database adapter driver override recognized for : [mysql-ab_jdbc_driver] - adapter: class org.apache.activemq.store.jdbc.adapter.MySqlJDBCAdapter As you can see the second broker did not fully initialize as it is waiting to acquire the database lock. If the master broker is killed, then you see the slave will acquire the database lock and becomes the new master. INFO | Database lock driver override not found for : [mysql-ab_jdbc_driver]. Will use default implementation. INFO | Attempting to acquire the exclusive lock to become the Master broker INFO | Becoming the master on dataSource: org.apache.commons.dbcp.BasicDataSource@2e19fc25 INFO | ActiveMQ 5.5.1-fuse-01-13 JMS Message Broker (jdbcBroker2) is starting INFO | For help or more information please see: http://activemq.apache.org/ INFO | Listening for connections at: tcp://macbookpro-251a.home:61617 INFO | Connector openwire Started INFO | ActiveMQ JMS Message Broker (jdbcBroker2, ID:macbookpro-251a.home-53193-1328656157052-0:1) started Summary As you can see, it is fairly simple and straight forward to configure a robust highly-available messaging system using ActiveMQ with database persistence.