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• emacs elisp buffer not running font lock mode until opened by user

  - by jacob

  My problem is I am opening a buffer using (set-buffer (find-tag-noselect (current-word))) and then I try to copy some text out of that buffer. The text that I get back has only the properties (fontified nil). find-tag-noselect automatically opens the buffer found in the TAGS file but it seems it does not run the font lock mode over it. When I manually switch to this buffer after it has been opened and then run the function again when it copies the text it has all the correct text properties attached. So what do I need to do to have this buffer completely initialized so that the correct syntax highlighting will be copied in?

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• how to set flex combobox cursor position

  - by crazy horse

  I have a combobox implementation as follows - Based on user input (min 2 chars) in the editable combobox, the data provider is refreshed and drop-down opened, showing different data sets as user input varies. Problem is that after drop-down opens, the cursor moves back to the beginning. So for instance, the user types in "ab", and wants to type in "c" to form the search string "abc". Due to the cursor re-setting its position to 0, the search string instead ends up as "cab". Here's what I tried already (doesn't work) : textInput.mx_internal::getTextField().setSelection(index, index); where index = length of user input. This selects text from index to index (which effectively un-selects text) and is supposed to place the cursor at the end. Any thoughts?

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• Android: Image displayed at Webview from Url with high quality loss

  - by Merlino

  I want to display an image from an url with an Webview at Android. With Android phones with Version 1.5 and 1.6 there is no problem. but the same pic and the same code on an AndroidPhone with Version 2.0 and the pic is totaly pixelated. Like Android is resizing the image first to a smaller one and then resizing it back to "normal" size. Unfortunately its important to display the pic without any quality loss. I tried to integrate it in the sourcefolder to show it as an normal image, but at Android 2.0 i get an exception because the image is to big. (At Android 1.6 there is no problem) Any ideas how i can display the image without quality loss with Android 2.0 ?

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• Any collaborative tool/website to localize an Android app?

  - by Nicolas Raoul

  My open source Android application has internationalization done the Android way, with strings.xml files. The community has many people from many countries, and they are willing to contribute/improve translations using a collaborative website. There is Launchpad but it only supports the gettext format so we would have to use scripts, not very convenient. There is Crowdin but somehow this website seems dead, nearly no projects, and the download links do not work. Actually we started using Crowdin but all download links fail to give any strings.xml file back, see here. What website is convenient for translating open source Android applications?

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• "Authorize" attribute and 403 error page

  - by zerkms

  [Authorize] property is nice and handy MS invention, and I hope it can solve the issues I have now To be more specific: When current client isn't authenticated - [Authorize] redirects from secured action to logon page and after logon was successfull - brings user back, this is good. But when current cilent already authenticated but not authorized to run specific action - all I need is to just display my general 403 page. Is it possible without moving authorization logic within controller's body? UPD: The behavior I need in should be semantically equals to this sketch: public ActionResult DoWork() { if (!NotAuthorized()) { return RedirectToAction("403"); } return View(); } so - there should no any redirect and url should be stay the same, but contents of the page should be replaced with 403-page

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• Using undecorated UiNavigationBar

  - by Nicsoft

  Hello, I would like to use UINavigationBar without decoration. I.e. I would like to create my own custom buttons and link those to the same actions (e.g. back) as the navigation items were linked to and have no bar presented at the top. I was told that one should use navigation bar even though graphically you should design the interaction yourself. How do I go about doing this? I am quite new to navigation bar to start with... If there is some tutorial you can direct me to it would be great (that is for using nav-bar without decoration). Thanks in advance! Regards, Niklas

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• LWJGL Voxel game, glDrawArrays

  - by user22015

  I've been learning about 3D for a couple days now. I managed to create a chunk (8x8x8). Add optimization so it only renders the active and visible blocks. Then I added so it only draws the faces which don't have a neighbor. Next what I found from online research was that it is better to use glDrawArrays to increase performance. So I restarted my little project. Render an entire chunck, add optimization so it only renders active and visible blocks. But now I want to add so it only draws the visible faces while using glDrawArrays. This is giving me some trouble with calling glDrawArrays because I'm passing a wrong count parameter. > # A fatal error has been detected by the Java Runtime Environment: > # > # EXCEPTION_ACCESS_VIOLATION (0xc0000005) at pc=0x0000000006e31a03, pid=1032, tid=3184 > # Stack: [0x00000000023a0000,0x00000000024a0000], sp=0x000000000249ef70, free space=1019k Native frames: (J=compiled Java code, j=interpreted, Vv=VM code, C=native code) C [ig4icd64.dll+0xa1a03] Java frames: (J=compiled Java code, j=interpreted, Vv=VM code) j org.lwjgl.opengl.GL11.nglDrawArrays(IIIJ)V+0 j org.lwjgl.opengl.GL11.glDrawArrays(III)V+20 j com.vox.block.Chunk.render()V+410 j com.vox.ChunkManager.render()V+30 j com.vox.Game.render()V+11 j com.vox.GameHandler.render()V+12 j com.vox.GameHandler.gameLoop()V+15 j com.vox.Main.main([Ljava/lang/StringV+13 v ~StubRoutines::call_stub public class Chunk { public final static int[] DIM = { 8, 8, 8}; public final static int CHUNK_SIZE = (DIM[0] * DIM[1] * DIM[2]); Block[][][] blocks; private int index; private int vBOVertexHandle; private int vBOColorHandle; public Chunk(int index) { this.index = index; vBOColorHandle = GL15.glGenBuffers(); vBOVertexHandle = GL15.glGenBuffers(); blocks = new Block[DIM[0]][DIM[1]][DIM[2]]; for(int x = 0; x < DIM[0]; x++){ for(int y = 0; y < DIM[1]; y++){ for(int z = 0; z < DIM[2]; z++){ blocks[x][y][z] = new Block(); } } } } public void render(){ Block curr; FloatBuffer vertexPositionData2 = BufferUtils.createFloatBuffer(CHUNK_SIZE * 6 * 12); FloatBuffer vertexColorData2 = BufferUtils.createFloatBuffer(CHUNK_SIZE * 6 * 12); int counter = 0; for(int x = 0; x < DIM[0]; x++){ for(int y = 0; y < DIM[1]; y++){ for(int z = 0; z < DIM[2]; z++){ curr = blocks[x][y][z]; boolean[] neightbours = validateNeightbours(x, y, z); if(curr.isActive() && !neightbours[6]) { float[] arr = curr.createCube((index*DIM[0]*Block.BLOCK_SIZE*2) + x*2, y*2, z*2, neightbours); counter += arr.length; vertexPositionData2.put(arr); vertexColorData2.put(createCubeVertexCol(curr.getCubeColor())); } } } } vertexPositionData2.flip(); vertexPositionData2.flip(); FloatBuffer vertexPositionData = BufferUtils.createFloatBuffer(vertexColorData2.position()); FloatBuffer vertexColorData = BufferUtils.createFloatBuffer(vertexColorData2.position()); for(int i = 0; i < vertexPositionData2.position(); i++) vertexPositionData.put(vertexPositionData2.get(i)); for(int i = 0; i < vertexColorData2.position(); i++) vertexColorData.put(vertexColorData2.get(i)); vertexColorData.flip(); vertexPositionData.flip(); GL15.glBindBuffer(GL15.GL_ARRAY_BUFFER, vBOVertexHandle); GL15.glBufferData(GL15.GL_ARRAY_BUFFER, vertexPositionData, GL15.GL_STATIC_DRAW); GL15.glBindBuffer(GL15.GL_ARRAY_BUFFER, 0); GL15.glBindBuffer(GL15.GL_ARRAY_BUFFER, vBOColorHandle); GL15.glBufferData(GL15.GL_ARRAY_BUFFER, vertexColorData, GL15.GL_STATIC_DRAW); GL15.glBindBuffer(GL15.GL_ARRAY_BUFFER, 0); GL11.glPushMatrix(); GL15.glBindBuffer(GL15.GL_ARRAY_BUFFER, vBOVertexHandle); GL11.glVertexPointer(3, GL11.GL_FLOAT, 0, 0L); GL15.glBindBuffer(GL15.GL_ARRAY_BUFFER, vBOColorHandle); GL11.glColorPointer(3, GL11.GL_FLOAT, 0, 0L); System.out.println("Counter " + counter); GL11.glDrawArrays(GL11.GL_LINE_LOOP, 0, counter); GL11.glPopMatrix(); //blocks[r.nextInt(DIM[0])][2][r.nextInt(DIM[2])].setActive(false); } //Random r = new Random(); private float[] createCubeVertexCol(float[] CubeColorArray) { float[] cubeColors = new float[CubeColorArray.length * 4 * 6]; for (int i = 0; i < cubeColors.length; i++) { cubeColors[i] = CubeColorArray[i % CubeColorArray.length]; } return cubeColors; } private boolean[] validateNeightbours(int x, int y, int z) { boolean[] bools = new boolean[7]; bools[6] = true; bools[6] = bools[6] && (bools[0] = y > 0 && y < DIM[1]-1 && blocks[x][y+1][z].isActive());//top bools[6] = bools[6] && (bools[1] = y > 0 && y < DIM[1]-1 && blocks[x][y-1][z].isActive());//bottom bools[6] = bools[6] && (bools[2] = z > 0 && z < DIM[2]-1 && blocks[x][y][z+1].isActive());//front bools[6] = bools[6] && (bools[3] = z > 0 && z < DIM[2]-1 && blocks[x][y][z-1].isActive());//back bools[6] = bools[6] && (bools[4] = x > 0 && x < DIM[0]-1 && blocks[x+1][y][z].isActive());//left bools[6] = bools[6] && (bools[5] = x > 0 && x < DIM[0]-1 && blocks[x-1][y][z].isActive());//right return bools; } } public class Block { public static final float BLOCK_SIZE = 1f; public enum BlockType { Default(0), Grass(1), Dirt(2), Water(3), Stone(4), Wood(5), Sand(6), LAVA(7); int BlockID; BlockType(int i) { BlockID=i; } } private boolean active; private BlockType type; public Block() { this(BlockType.Default); } public Block(BlockType type){ active = true; this.type = type; } public float[] getCubeColor() { switch (type.BlockID) { case 1: return new float[] { 1, 1, 0 }; case 2: return new float[] { 1, 0.5f, 0 }; case 3: return new float[] { 0, 0f, 1f }; default: return new float[] {0.5f, 0.5f, 1f}; } } public float[] createCube(float x, float y, float z, boolean[] neightbours){ int counter = 0; for(boolean b : neightbours) if(!b) counter++; float[] array = new float[counter*12]; int offset = 0; if(!neightbours[0]){//top array[offset++] = x*BLOCK_SIZE + BLOCK_SIZE; array[offset++] = y*BLOCK_SIZE + BLOCK_SIZE; array[offset++] = z*BLOCK_SIZE - BLOCK_SIZE; array[offset++] = x*BLOCK_SIZE - BLOCK_SIZE; array[offset++] = y*BLOCK_SIZE + BLOCK_SIZE; array[offset++] = z*BLOCK_SIZE - BLOCK_SIZE; array[offset++] = x*BLOCK_SIZE - BLOCK_SIZE; array[offset++] = y*BLOCK_SIZE + BLOCK_SIZE; array[offset++] = z*BLOCK_SIZE + BLOCK_SIZE; array[offset++] = x*BLOCK_SIZE + BLOCK_SIZE; array[offset++] = y*BLOCK_SIZE + BLOCK_SIZE; array[offset++] = z*BLOCK_SIZE + BLOCK_SIZE; } if(!neightbours[1]){//bottom array[offset++] = x*BLOCK_SIZE + BLOCK_SIZE; array[offset++] = y*BLOCK_SIZE - BLOCK_SIZE; array[offset++] = z*BLOCK_SIZE + BLOCK_SIZE; array[offset++] = x*BLOCK_SIZE - BLOCK_SIZE; array[offset++] = y*BLOCK_SIZE - BLOCK_SIZE; array[offset++] = z*BLOCK_SIZE + BLOCK_SIZE; array[offset++] = x*BLOCK_SIZE - BLOCK_SIZE; array[offset++] = y*BLOCK_SIZE - BLOCK_SIZE; array[offset++] = z*BLOCK_SIZE - BLOCK_SIZE; array[offset++] = x*BLOCK_SIZE + BLOCK_SIZE; array[offset++] = y*BLOCK_SIZE - BLOCK_SIZE; array[offset++] = z*BLOCK_SIZE - BLOCK_SIZE; } if(!neightbours[2]){//front array[offset++] = x*BLOCK_SIZE + BLOCK_SIZE; array[offset++] = y*BLOCK_SIZE + BLOCK_SIZE; array[offset++] = z*BLOCK_SIZE + BLOCK_SIZE; array[offset++] = x*BLOCK_SIZE - BLOCK_SIZE; array[offset++] = y*BLOCK_SIZE + BLOCK_SIZE; array[offset++] = z*BLOCK_SIZE + BLOCK_SIZE; array[offset++] = x*BLOCK_SIZE - BLOCK_SIZE; array[offset++] = y*BLOCK_SIZE - BLOCK_SIZE; array[offset++] = z*BLOCK_SIZE + BLOCK_SIZE; array[offset++] = x*BLOCK_SIZE + BLOCK_SIZE; array[offset++] = y*BLOCK_SIZE - BLOCK_SIZE; array[offset++] = z*BLOCK_SIZE + BLOCK_SIZE; } if(!neightbours[3]){//back array[offset++] = x*BLOCK_SIZE + BLOCK_SIZE; array[offset++] = y*BLOCK_SIZE - BLOCK_SIZE; array[offset++] = z*BLOCK_SIZE - BLOCK_SIZE; array[offset++] = x*BLOCK_SIZE - BLOCK_SIZE; array[offset++] = y*BLOCK_SIZE - BLOCK_SIZE; array[offset++] = z*BLOCK_SIZE - BLOCK_SIZE; array[offset++] = x*BLOCK_SIZE - BLOCK_SIZE; array[offset++] = y*BLOCK_SIZE + BLOCK_SIZE; array[offset++] = z*BLOCK_SIZE - BLOCK_SIZE; array[offset++] = x*BLOCK_SIZE + BLOCK_SIZE; array[offset++] = y*BLOCK_SIZE + BLOCK_SIZE; array[offset++] = z*BLOCK_SIZE - BLOCK_SIZE; } if(!neightbours[4]){//left array[offset++] = x*BLOCK_SIZE - BLOCK_SIZE; array[offset++] = y*BLOCK_SIZE + BLOCK_SIZE; array[offset++] = z*BLOCK_SIZE + BLOCK_SIZE; array[offset++] = x*BLOCK_SIZE - BLOCK_SIZE; array[offset++] = y*BLOCK_SIZE + BLOCK_SIZE; array[offset++] = z*BLOCK_SIZE - BLOCK_SIZE; array[offset++] = x*BLOCK_SIZE - BLOCK_SIZE; array[offset++] = y*BLOCK_SIZE - BLOCK_SIZE; array[offset++] = z*BLOCK_SIZE - BLOCK_SIZE; array[offset++] = x*BLOCK_SIZE - BLOCK_SIZE; array[offset++] = y*BLOCK_SIZE - BLOCK_SIZE; array[offset++] = z*BLOCK_SIZE + BLOCK_SIZE; } if(!neightbours[5]){//right array[offset++] = x*BLOCK_SIZE + BLOCK_SIZE; array[offset++] = y*BLOCK_SIZE + BLOCK_SIZE; array[offset++] = z*BLOCK_SIZE - BLOCK_SIZE; array[offset++] = x*BLOCK_SIZE + BLOCK_SIZE; array[offset++] = y*BLOCK_SIZE + BLOCK_SIZE; array[offset++] = z*BLOCK_SIZE + BLOCK_SIZE; array[offset++] = x*BLOCK_SIZE + BLOCK_SIZE; array[offset++] = y*BLOCK_SIZE - BLOCK_SIZE; array[offset++] = z*BLOCK_SIZE + BLOCK_SIZE; array[offset++] = x*BLOCK_SIZE + BLOCK_SIZE; array[offset++] = y*BLOCK_SIZE - BLOCK_SIZE; array[offset++] = z*BLOCK_SIZE - BLOCK_SIZE; } return Arrays.copyOf(array, offset); } public boolean isActive() { return active; } public void setActive(boolean active) { this.active = active; } public BlockType getType() { return type; } public void setType(BlockType type) { this.type = type; } } I highlighted the code I'm concerned about in this following screenshot: - http://imageshack.us/a/img820/7606/18626782.png - (Not allowed to upload images yet) I know the code is a mess but I'm just testing stuff so I wasn't really thinking about it.

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• Changing data in a django modelform

  - by Matt Hampel

  I get data in from POST and validate it via this standard snippet: entry_formset = EntryFormSet(request.POST, request.FILES, prefix='entries') if entry_formset.is_valid(): .... The EntryFormSet modelform overrides a foreign key field widget to present a text field. That way, the user can enter an existing key (suggested via an Ajax live search), or enter a new key, which will be seamlessly added. I use this try-except block to test if the object exists already, and if it doesn't, I add it. entity_name = request.POST['entries-0-entity'] try: entity = Entity.objects.get(name=entity_name) except Entity.DoesNotExist: entity = Entity(name=entity_name) entity.slug = slugify(entity.name) entity.save() However, I now need to get that entity back into the entry_formset. It thinks that entries-0-entity is a string (that's how it came in); how can I directly access that value of the entry_formset and get it to take the object reference instead?

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• XML to DOC to PDF

  - by Max

  what is the easiest(and fastest) way to perform this kind of transformation: "Data in XML" to "Some MS Word 2003 Supported format" to PDF using Java? My first guess was to fill the template with XML data (using Placeholders for example) and then save it and convert it to PDF. But I can't just put placeholders to DOC files, and I can't convert from some other Word formats to PDF... My primary task is to convert XML Data to PDF allowing users to change the PDF on-demand. The best way to change the PDF on-demand seems to give user some kind of MS Word readable document, and then convert it back. There are 2 main problems with this task: 1) I can't use OpenOffice for conversion. 2) System should be able to convert ~1 page of table-based document per 1 second on 2Ghz Core. 3) RTF does not provide enough styling, so some more complex format should be used. Thanks in advance.

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• Global "ajax call" notification with asp.net mvc/jquery

  - by Joel Martinez

  I need to be notified any time a largeish asp.net mvc web application makes an ajax call to the server. We're using both jquery, and the built-in Ajax.* methods to do the remote calls, and I would like a global way of knowing when we make a call without having to manually inject some sort of "IsMakingCall" method to every request. The root problem we're trying to solve is session timeout. If the user leaves a page up and goes to lunch (for example), they get errors when they get back because the ajax call is returning the login page instead of the expected json or partial html result. My idea was to have a js timer which would be reset any time we make an ajax call. That way, if the timer runs out (ie. their session has now timed out) I can just auto-log them out. This is how sites like bank of america and mint.com work. Thanks!

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• Where can I find a description of the old British Standard structured flow charts?

  - by Steve314

  Some professional organisation defined these in, IIRC, the early 80s as similar to the more well known flow charts, but "structured". Instead of having arbitrary "goto" arrows, they had the equivalent of loops etc. They were standardized, and I vaguely remember studying them briefly at O Level. Of course they were about as useful as the well-known chocolate teapot, but I'd still like to be able to find a reference guide for them if possible - for roughly the same reason I was looking for a reference for standard Basic a while back. Google tells me - well, nothing really. They may as well never have existed. Which is probably nearly (and perhaps completely) true - I certainly never heard of them anywhere else except when I was at school. There's a chance that they may even be my computer science teachers little joke.

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• EF4, MVC 3, Azure and Code First or Traditional

  - by RichardAlanA

  I am planning to build a web application using ASP MVC3 that runs on Azure with a SQL Azure back end. I would like to use the Microsoft stack and have no plans to ever change to another stack. I am looking into the use of WCF and WF but that would be in the future. I looked at the traditional and Code First approach to using Entity Framework but I can't see if there is any advantage in using one or the other approach. Sure they each have advantages but for me I don't care if my classes do inherit from EF classes. All I want is to find the most efficient solution. Can anyone out there give me some advice as to which approach might be the best. thanks very much Richard

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• Is is possible to to have a depends on a jQuery remote validation?

  - by David Kethel

  I am using jQuery remote validation to check if the description is already being used. Description: { required: true, maxlength: 20, remote: function () { var newDescription = $("#txtDescription").val(); var dataInput = { geoFenceDescription: newDescription }; var r = { type: "POST", url: "/ATOMWebService.svc/DoesGeoFenceDescriptionExist", data: JSON.stringify(dataInput), contentType: "application/json; charset=utf-8", dataType: "json", dataFilter: function (data) { var x = (JSON.parse(data)).d; return JSON.stringify(!x); } }; return r; } }, The problem I have is that this remote validation occurs when the user has NOT modified the text box and comes back saying the description has been used because it found it self in the database. So is it possible to only run the remote validation if the text field is different to what was originally in it? I noticed the the jQuery required validation has a depends option, but I couldn't get it to work with the remote call.

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• Enable Session state in sharePoint 2010

  - by Albert D. Kallal

  I setup a test box computer with server 2008 (standard edition, not R2 and not hyper-v editing). I then installed SharePoint 2010. I was amazed how easy the whole setup went (the prerequisites setup on the SharePoint disk made this process oh so easy – great install system). Really this was just so easy. This test box is being used for testing Access web services. I am able to well publish access applications to this test server and Access applications publish and run just fine on the web SharePoint site through an web browser. However, the only thing that does not work is when I launch a Access report. The error message I get back is This report failed to load because session state is not turned on. Here is a screen shot: I can’t seem to find the setting anywhere to turn session state on. Any hints or links on how to enable session state in SharePoint 2010 would be most appreciated.

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• The case of the phantom ADF developer (and other yarns)

  - by Chris Muir

  A few years of ADF experience means I see common mistakes made by different developers, some I regularly make myself.  This post is designed to assist beginners to Oracle JDeveloper Application Development Framework (ADF) avoid a common ADF pitfall, the case of the phantom ADF developer [add Scooby-Doo music here]. ADF Business Components - triggers, default table values and instead of views. Oracle's JDeveloper tutorials help with the A-B-Cs of ADF development, typically built on the nice 'n safe demo schema provided by with the Oracle database such as the HR demo schema. However it's not too long until ADF beginners, having built up some confidence from learning with the tutorials and vanilla demo schemas, start building ADF Business Components based upon their own existing database schema objects.  This is where unexpected problems can sneak in. The crime Developers may encounter a surprising error at runtime when editing a record they just created or updated and committed to the database, based on their own existing tables, namely the error: JBO-25014: Another user has changed the row with primary key oracle.jbo.Key[x] ...where X is the primary key value of the row at hand.  In a production environment with multiple users this error may be legit, one of the other users has updated the row since you queried it.  Yet in a development environment this error is just plain confusing.  If developers are isolated in their own database, creating and editing records they know other users can't possibly be working with, or all the other developers have gone home for the day, how is this error possible? There are no other users?  It must be the phantom ADF developer! [insert dramatic music here] The following picture is what you'll see in the Business Component Browser, and you'll receive a similar error message via an ADF Faces page: A false conclusion What can possibly cause this issue if it isn't our phantom ADF developer?  Doesn't ADF BC implement record locking, locking database records when the row is modified in the ADF middle-tier by a user?  How can our phantom ADF developer even take out a lock if this is the case?  Maybe ADF has a bug, maybe ADF isn't implementing record locking at all?  Shouldn't we see the error "JBO-26030: Failed to lock the record, another user holds the lock" as we attempt to modify the record, why do we see JBO-25014? : Let's verify that ADF is in fact issuing the correct SQL LOCK-FOR-UPDATE statement to the database. First we need to verify ADF's locking strategy.  It is determined by the Application Module's jbo.locking.mode property.  The default (as of JDev 11.1.1.4.0 if memory serves me correct) and recommended value is optimistic, and the other valid value is pessimistic. Next we need a mechanism to check that ADF is issuing the LOCK statements to the database.  We could ask DBAs to monitor locks with OEM, but optimally we'd rather not involve overworked DBAs in this process, so instead we can use the ADF runtime setting –Djbo.debugoutput=console.  At runtime this options turns on instrumentation within the ADF BC layer, which among a lot of extra detail displayed in the log window, will show the actual SQL statement issued to the database, including the LOCK statement we're looking to confirm. Setting our locking mode to pessimistic, opening the Business Components Browser of a JSF page allowing us to edit a record, say the CHARGEABLE field within a BOOKINGS record where BOOKING_NO = 1206, upon editing the record see among others the following log entries: [421] Built select: 'SELECT BOOKING_NO, EVENT_NO, RESOURCE_CODE, CHARGEABLE, MADE_BY, QUANTITY, COST, STATUS, COMMENTS FROM BOOKINGS Bookings'[422] Executing LOCK...SELECT BOOKING_NO, EVENT_NO, RESOURCE_CODE, CHARGEABLE, MADE_BY, QUANTITY, COST, STATUS, COMMENTS FROM BOOKINGS Bookings WHERE BOOKING_NO=:1 FOR UPDATE NOWAIT[423] Where binding param 1: 1206  As can be seen on line 422, in fact a LOCK-FOR-UPDATE is indeed issued to the database.  Later when we commit the record we see: [441] OracleSQLBuilder: SAVEPOINT 'BO_SP'[442] OracleSQLBuilder Executing, Lock 1 DML on: BOOKINGS (Update)[443] UPDATE buf Bookings>#u SQLStmtBufLen: 210, actual=62[444] UPDATE BOOKINGS Bookings SET CHARGEABLE=:1 WHERE BOOKING_NO=:2[445] Update binding param 1: N[446] Where binding param 2: 1206[447] BookingsView1 notify COMMIT ... [448] _LOCAL_VIEW_USAGE_model_Bookings_ResourceTypesView1 notify COMMIT ... [449] EntityCache close prepared statement ....and as a result the changes are saved to the database, and the lock is released. Let's see what happens when we use the optimistic locking mode, this time to change the same BOOKINGS record CHARGEABLE column again.  As soon as we edit the record we see little activity in the logs, nothing to indicate any SQL statement, let alone a LOCK has been taken out on the row. However when we save our records by issuing a commit, the following is recorded in the logs: [509] OracleSQLBuilder: SAVEPOINT 'BO_SP'[510] OracleSQLBuilder Executing doEntitySelect on: BOOKINGS (true)[511] Built select: 'SELECT BOOKING_NO, EVENT_NO, RESOURCE_CODE, CHARGEABLE, MADE_BY, QUANTITY, COST, STATUS, COMMENTS FROM BOOKINGS Bookings'[512] Executing LOCK...SELECT BOOKING_NO, EVENT_NO, RESOURCE_CODE, CHARGEABLE, MADE_BY, QUANTITY, COST, STATUS, COMMENTS FROM BOOKINGS Bookings WHERE BOOKING_NO=:1 FOR UPDATE NOWAIT[513] Where binding param 1: 1205[514] OracleSQLBuilder Executing, Lock 2 DML on: BOOKINGS (Update)[515] UPDATE buf Bookings>#u SQLStmtBufLen: 210, actual=62[516] UPDATE BOOKINGS Bookings SET CHARGEABLE=:1 WHERE BOOKING_NO=:2[517] Update binding param 1: Y[518] Where binding param 2: 1205[519] BookingsView1 notify COMMIT ... [520] _LOCAL_VIEW_USAGE_model_Bookings_ResourceTypesView1 notify COMMIT ... [521] EntityCache close prepared statement Again even though we're seeing the midtier delay the LOCK statement until commit time, it is in fact occurring on line 412, and released as part of the commit issued on line 419.  Therefore with either optimistic or pessimistic locking a lock is indeed issued. Our conclusion at this point must be, unless there's the unlikely cause the LOCK statement is never really hitting the database, or the even less likely cause the database has a bug, then ADF does in fact take out a lock on the record before allowing the current user to update it.  So there's no way our phantom ADF developer could even modify the record if he tried without at least someone receiving a lock error. Hmm, we can only conclude the locking mode is a red herring and not the true cause of our problem.  Who is the phantom? At this point we'll need to conclude that the error message "JBO-25014: Another user has changed" is somehow legit, even though we don't understand yet what's causing it. This leads onto two further questions, how does ADF know another user has changed the row, and what's been changed anyway? To answer the first question, how does ADF know another user has changed the row, the Fusion Guide's section 4.10.11 How to Protect Against Losing Simultaneous Updated Data , that details the Entity Object Change-Indicator property, gives us the answer: At runtime the framework provides automatic "lost update" detection for entity objects to ensure that a user cannot unknowingly modify data that another user has updated and committed in the meantime. Typically, this check is performed by comparing the original values of each persistent entity attribute against the corresponding current column values in the database at the time the underlying row is locked. Before updating a row, the entity object verifies that the row to be updated is still consistent with the current state of the database.  The guide further suggests to make this solution more efficient: You can make the lost update detection more efficient by identifying any attributes of your entity whose values you know will be updated whenever the entity is modified. Typical candidates include a version number column or an updated date column in the row.....To detect whether the row has been modified since the user queried it in the most efficient way, select the Change Indicator option to compare only the change-indicator attribute values. We now know that ADF BC doesn't use the locking mechanism at all to protect the current user against updates, but rather it keeps a copy of the original record fetched, separate to the user changed version of the record, and it compares the original record against the one in the database when the lock is taken out.  If values don't match, be it the default compare-all-columns behaviour, or the more efficient Change Indicator mechanism, ADF BC will throw the JBO-25014 error. This leaves one last question.  Now we know the mechanism under which ADF identifies a changed row, what we don't know is what's changed and who changed it? The real culprit What's changed?  We know the record in the mid-tier has been changed by the user, however ADF doesn't use the changed record in the mid-tier to compare to the database record, but rather a copy of the original record before it was changed.  This leaves us to conclude the database record has changed, but how and by who? There are three potential causes: Database triggers The database trigger among other uses, can be configured to fire PLSQL code on a database table insert, update or delete.  In particular in an insert or update the trigger can override the value assigned to a particular column.  The trigger execution is actioned by the database on behalf of the user initiating the insert or update action. Why this causes the issue specific to our ADF use, is when we insert or update a record in the database via ADF, ADF keeps a copy of the record written to the database.  However the cached record is instantly out of date as the database triggers have modified the record that was actually written to the database.  Thus when we update the record we just inserted or updated for a second time to the database, ADF compares its original copy of the record to that in the database, and it detects the record has been changed – giving us JBO-25014. This is probably the most common cause of this problem. Default values A second reason this issue can occur is another database feature, default column values.  When creating a database table the schema designer can define default values for specific columns.  For example a CREATED_BY column could be set to SYSDATE, or a flag column to Y or N.  Default values are only used by the database when a user inserts a new record and the specific column is assigned NULL.  The database in this case will overwrite the column with the default value. As per the database trigger section, it then becomes apparent why ADF chokes on this feature, though it can only specifically occur in an insert-commit-update-commit scenario, not the update-commit-update-commit scenario. Instead of trigger views I must admit I haven't double checked this scenario but it seems plausible, that of the Oracle database's instead of trigger view (sometimes referred to as instead of views).  A view in the database is based on a query, and dependent on the queries complexity, may support insert, update and delete functionality to a limited degree.  In order to support fully insertable, updateable and deletable views, Oracle introduced the instead of view, that gives the view designer the ability to not only define the view query, but a set of programmatic PLSQL triggers where the developer can define their own logic for inserts, updates and deletes. While this provides the database programmer a very powerful feature, it can cause issues for our ADF application.  On inserting or updating a record in the instead of view, the record and it's data that goes in is not necessarily the data that comes out when ADF compares the records, as the view developer has the option to practically do anything with the incoming data, including throwing it away or pushing it to tables which aren't used by the view underlying query for fetching the data. Readers are at this point reminded that this article is specifically about how the JBO-25014 error occurs in the context of 1 developer on an isolated database.  The article is not considering how the error occurs in a production environment where there are multiple users who can cause this error in a legitimate fashion.  Assuming none of the above features are the cause of the problem, and optimistic locking is turned on (this error is not possible if pessimistic locking is the default mode *and* none of the previous causes are possible), JBO-25014 is quite feasible in a production ADF application if 2 users modify the same record. At this point under project timelines pressure, the obvious fix for developers is to drop both database triggers and default values from the underlying tables.  However we must be careful that these legacy constructs aren't used and assumed to be in place by other legacy systems.  Dropping the database triggers or default value that the existing Oracle Forms  applications assumes and requires to be in place could cause unexpected behaviour and bugs in the Forms application.  Proficient software engineers would recognize such a change may require a partial or full regression test of the existing legacy system, a potentially costly and timely exercise, not ideal. Solving the mystery once and for all Luckily ADF has built in functionality to deal with this issue, though it's not a surprise, as Oracle as the author of ADF also built the database, and are fully aware of the Oracle database's feature set.  At the Entity Object attribute level, the Refresh After Insert and Refresh After Update properties.  Simply selecting these instructs ADF BC after inserting or updating a record to the database, to expect the database to modify the said attributes, and read a copy of the changed attributes back into its cached mid-tier record.  Thus next time the developer modifies the current record, the comparison between the mid-tier record and the database record match, and JBO-25014: Another user has changed" is no longer an issue. [Post edit - as per the comment from Oracle's Steven Davelaar below, as he correctly points out the above solution will not work for instead-of-triggers views as it relies on SQL RETURNING clause which is incompatible with this type of view] Alternatively you can set the Change Indicator on one of the attributes.  This will work as long as the relating column for the attribute in the database itself isn't inadvertently updated.  In turn you're possibly just masking the issue rather than solving it, because if another developer turns the Change Indicator back on the original issue will return.

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• BlackBerry Storm - Cannot scroll vertically while in TreeField

  - by sethxian

  I am having issues performing a vertical scroll on the BlackBerry Storm while in a TreeField. The tree nodes expand just fine, even with expanded nodes while in the tree I cannot scroll to the bottom of the expanded list. Sometimes it will scroll a little but then not allow me to scroll back up. Could this be an issue with the screen not being a fixed size? The TreeField is in a VeriticalFieldManager with the VERTICAL_SCROLL and VERTICAL_SCROLLBAR styles. The screen I am using is MainScreen.

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• Library to parse ERB files

  - by Douglas Sellers

  I am attempting to parse, not evaluate, rails ERB files in a Hpricot/Nokogiri type manner. The files I am attempting to parse contain HTML fragments intermixed with dynamic content generated using ERB (standard rails view files) I am looking for a library that will not only parse the surrounding content, much the way that Hpricot or Nokogiri will but will also treat the ERB symbols, <%, <%= etc, as though they were html/xml tags. Ideally I would get back a DOM like structure where the <%, <%= etc symbols would be included as their own node types. I know that it is possible to hack something together using regular expressions but I was looking for something a bit more reliable as I am developing a tool that I need to run on a very large view code base where both the html content and the erb content are important. For example, content such as: blah blah blah <divMy Great Text <%= my_dynamic_expression %</div Would return a tree structure like: root - text_node (blah blah blah) - element (div) - text_node (My Great Text ) - erb_node (<%=)

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• How do the young start programming nowadays

  - by PP

  Back in the late 80s/early 90s I learned GWBasic on MS-DOS. Then Turbo Pascal. Then Turbo C/Asm. Later I stumbled into PHP and finally made a career out of Perl programming. I'm curious how actual under-25s found their way into programming. There is a lot of discussion about what path you would steer your children if you wanted them to learn programming, but I would like to hear from the newer generation to find out their more modern experiences about becoming a programmer. Note: no stories from people who first discovered programming at university.

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• ASP.Net MVC ReturnUrl Practice

  - by Terry

  I have a question about the returnUrl querystring parameter that is appended by ASP.Net when attempted to hit a page that requires authentication. In looking at Microsoft NerdDinner Sample's LogOn action (along with every other 'sample authentication code' I see on the 'net), it just has the ReturnUrl parameter declared in the action's signature and uses it directly in a Redirect() call. However, back in the WebForms days and using Membership Controls, we use to use the FormsAuthentication.GetReturnUrl() call. Besides returning the 'default url' if no url was specified in the querystring, it also does a few security checks (Cross App Redirect and 'IsDangerousUrl()'). Are those no longer a concern or are all the sample 'log on' actions I'm seeing all over the 'net just ignoring those issues?

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• Getting LEGEND tags to wrap text properly.

  - by DA

  Legend tags are always a nuisance as they don't adhere to a lot of CSS rules. I'm trying to get the text within a LEGEND tag to wrap using the typical solution of wrapping the text in the LEGEND with a span and setting the width and display: block. <legend> <span style="border: 1px solid blue; width: 250px; display: block"> This text should wrap if it gets longer than 250px in width </span> </legend> I thought this used to work In Firefox, but does not appear to work anymore in 3.6. Sample: http://jsbin.com/exeno/5 It still works in IE. Has anyone found a fix for this or is it just a matter of forgoing LEGEND tags and go back to H# tags?

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• Style: Dot notation vs. message notation in Objective-C 2.0

  - by groundhog

  In Objective-C 2.0 we got the "dot" notation for properties. I've seen various back and forths about the merits of dot notation vs. message notation. To keep the responses untainted I'm not going to respond either way in the question. What is your thought about dot notation vs. message notation for property accessing? Please try to keep it focused on Objective-C - my one bias I'll put forth is that Objective-C is Objective-C, so your preference that it be like Java or JavaScript aren't valid. Valid commentary is to do with technical issues (operation ordering, cast precedence, performance, etc), clarity (structure vs. object nature, both pro and con!), succinctness, etc. Note, I'm of the school of rigorous quality and readability in code having worked on huge projects where code convention and quality is paramount (the write once read a thousand times paradigm).

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• [Rails] OAuth with Digg API

  - by Karl

  I'm attempting to get Rails to play nice with the Digg API's OAuth. I'm using the oauth gem (ruby one, not the rails one). My code looks approximately like this: @consumer = OAuth::Consumer.new(API_KEY, API_SECRET, :scheme => :header, :http_method => :post, :oauth_callback => "http://locahost:3000", :request_token_url => 'http://services.digg.com/1.0/endpoint?method=oauth.getRequestToken', :access_token_url => 'http://services.digg.com/1.0/endpoint?method=oauth.getAccessToken', :authorize_url => 'http://digg.com/oauth/authorize') @request_token = @consumer.get_request_token session[:request_token] = @request_token.token session[:request_token_secret] = @request_token.secret redirect_to @request_token.authorize_url Which is by-the-book in terms of what the gem documentation gave me. However, Digg spits a "400 Bad Request" error back at me when @consumer.get_request_token is called. I can't figure out what I'm doing wrong. Any ideas?

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• What are the best programming and development related Blogs?

  - by Christopher Cashell

  There are lots of great resources available on the Internet for learning more about programming and improving your skills. Blogs are one of the best, IMO. There's a wealth of knowledge and experience, much of it covering topics not often found in traditional books, and the increased community aspect helps to bring in multiple viewpoints and ideas. We're probably all familiar with Coding Horror and Joel on Software (so no need to mention them), but what are the other great ones out there? What are the Blogs that you find yourself following most closely? Where you see the best new ideas, the most interesting or informative ideas, or just the posts that make you sit back and think? One Blog per answer, and then we'll vote up the best so we can all learn from them.

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• The Incremental Architect&acute;s Napkin - #2 - Balancing the forces

  - by Ralf Westphal

  Originally posted on: http://geekswithblogs.net/theArchitectsNapkin/archive/2014/06/02/the-incremental-architectacutes-napkin---2---balancing-the-forces.aspxCategorizing requirements is the prerequisite for ecconomic architectural decisions. Not all requirements are created equal. However, to truely understand and describe the requirement forces pulling on software development, I think further examination of the requirements aspects is varranted. Aspects of Functionality There are two sides to Functionality requirements. It´s about what a software should do. I call that the Operations it implements. Operations are defined by expressions and control structures or calls to frameworks of some sort, i.e. (business) logic statements. Operations calculate, transform, aggregate, validate, send, receive, load, store etc. Operations are about behavior; they take input and produce output by considering state. I´m not using the term “function” here, because functions - or methods or sub-programs - are not necessary to implement Operations. Functions belong to a different sub-aspect of requirements (see below). Operations alone are not enough, though, to make a customer happy with regard to his/her Functionality requirements. Only correctly implemented Operations provide full value. This should make clear, why testing is so important. And not just manual tests during development of some operational feature, but automated tests. Because only automated tests scale when over time the number of operations increases. Without automated tests there is no guarantee formerly correct operations are still correct after more got added. To retest all previous operations manually is infeasible. So whoever relies just on manual tests is not really balancing the two forces Operations and Correctness. With manual tests more weight is put on the side of the scale of Operations. That might be ok for a short period of time - but in the long run it will bite you. You need to plan for Correctness in the long run from the first day of your project on. Aspects of Quality As important as Functionality is, it´s not the driver for software development. No software has ever been written to just implement some operation in code. We don´t need computers just to do something. All computers can do with software we can do without them. Well, at least given enough time and resources. We could calculate the most complex formulas without computers. We could do auctions with millions of people without computers. The only reason we want computers to help us with this and a million other Operations is… We don´t want to wait for the results very long. Or we want less errors. Or we want easier accessability to complicated solutions. So the main reason for customers to buy/order software is some Quality. They want some Functionality with a higher Quality (e.g. performance, scalability, usability, security…) than without the software. But Qualities come in at least two flavors: Most important are Primary Qualities. That´s the Qualities software truely is written for. Take an online auction website for example. Its Primary Qualities are performance, scalability, and usability, I´d say. Auctions should come within reach of millions of people; setting up an auction should be very easy; finding a suitable auction and bidding on it should be as fast as possible. Only if those Qualities have been implemented does security become relevant. A secure auction website is important - but not as important as a fast auction website. Nobody would want to use the most secure auction website if it was unbearably slow. But there would be people willing to use the fastest auction website even it was lacking security. That´s why security - with regard to online auction software - is not a Primary Quality, but just a Secondary Quality. It´s a supporting quality, so to speak. It does not deliver value by itself. With a password manager software this might be different. There security might be a Primary Quality. Please get me right: I don´t want to denigrate any Quality. There´s a long list of non-functional requirements at Wikipedia. They are all created equal - but that does not mean they are equally important for all software projects. When confronted with Quality requirements check with the customer which are primary and which are secondary. That will help to make good economical decisions when in a crunch. Resources are always limited - but requirements are a bottomless ocean. Aspects of Security of Investment Functionality and Quality are traditionally the requirement aspects cared for most - by customers and developers alike. Even today, when pressure rises in a project, tunnel vision will focus on them. Any measures to create and hold up Security of Investment (SoI) will be out of the window pretty quickly. Resistance to customers and/or management is futile. As long as SoI is not placed on equal footing with Functionality and Quality it´s bound to suffer under pressure. To look closer at what SoI means will help to become more conscious about it and make customers and management aware of the risks of neglecting it. SoI to me has two facets: Production Efficiency (PE) is about speed of delivering value. Customers like short response times. Short response times mean less money spent. So whatever makes software development faster supports this requirement. This must not lead to duct tape programming and banging out features by the dozen, though. Because customers don´t just want Operations and Quality, but also Correctness. So if Correctness gets compromised by focussing too much on Production Efficiency it will fire back. Customers want PE not just today, but over the whole course of a software´s lifecycle. That means, it´s not just about coding speed, but equally about code quality. If code quality leads to rework the PE is on an unsatisfactory level. Also if code production leads to waste it´s unsatisfactory. Because the effort which went into waste could have been used to produce value. Rework and waste cost money. Rework and waste abound, however, as long as PE is not addressed explicitly with management and customers. Thanks to the Agile and Lean movements that´s increasingly the case. Nevertheless more could and should be done in many teams. Each and every developer should keep in mind that Production Efficiency is as important to the customer as Functionality and Quality - whether he/she states it or not. Making software development more efficient is important - but still sooner or later even agile projects are going to hit a glas ceiling. At least as long as they neglect the second SoI facet: Evolvability. Delivering correct high quality functionality in short cycles today is good. But not just any software structure will allow this to happen for an indefinite amount of time.[1] The less explicitly software was designed the sooner it´s going to get stuck. Big ball of mud, monolith, brownfield, legacy code, technical debt… there are many names for software structures that have lost the ability to evolve, to be easily changed to accomodate new requirements. An evolvable code base is the opposite of a brownfield. It´s code which can be easily understood (by developers with sufficient domain expertise) and then easily changed to accomodate new requirements. Ideally the costs of adding feature X to an evolvable code base is independent of when it is requested - or at least the costs should only increase linearly, not exponentially.[2] Clean Code, Agile Architecture, and even traditional Software Engineering are concerned with Evolvability. However, it seems no systematic way of achieving it has been layed out yet. TDD + SOLID help - but still… When I look at the design ability reality in teams I see much room for improvement. As stated previously, SoI - or to be more precise: Evolvability - can hardly be measured. Plus the customer rarely states an explicit expectation with regard to it. That´s why I think, special care must be taken to not neglect it. Postponing it to some large refactorings should not be an option. Rather Evolvability needs to be a core concern for every single developer day. This should not mean Evolvability is more important than any of the other requirement aspects. But neither is it less important. That´s why more effort needs to be invested into it, to bring it on par with the other aspects, which usually are much more in focus. In closing As you see, requirements are of quite different kinds. To not take that into account will make it harder to understand the customer, and to make economic decisions. Those sub-aspects of requirements are forces pulling in different directions. To improve performance might have an impact on Evolvability. To increase Production Efficiency might have an impact on security etc. No requirement aspect should go unchecked when deciding how to allocate resources. Balancing should be explicit. And it should be possible to trace back each decision to a requirement. Why is there a null-check on parameters at the start of the method? Why are there 5000 LOC in this method? Why are there interfaces on those classes? Why is this functionality running on the threadpool? Why is this function defined on that class? Why is this class depending on three other classes? These and a thousand more questions are not to mean anything should be different in a code base. But it´s important to know the reason behind all of these decisions. Because not knowing the reason possibly means waste and having decided suboptimally. And how do we ensure to balance all requirement aspects? That needs practices and transparency. Practices means doing things a certain way and not another, even though that might be possible. We´re dealing with dangerous tools here. Like a knife is a dangerous tool. Harm can be done if we use our tools in just any way at the whim of the moment. Over the centuries rules and practices have been established how to use knifes. You don´t put them in peoples´ legs just because you´re feeling like it. You hand over a knife with the handle towards the receiver. You might not even be allowed to cut round food like potatos or eggs with it. The same should be the case for dangerous tools like object-orientation, remote communication, threads etc. We need practices to use them in a way so requirements are balanced almost automatically. In addition, to be able to work on software as a team we need transparency. We need means to share our thoughts, to work jointly on mental models. So far our tools are focused on working with code. Testing frameworks, build servers, DI containers, intellisense, refactoring support… That´s all nice and well. I don´t want to miss any of that. But I think it´s not enough. We´re missing mental tools, tools for making thinking and talking about software (independently of code) easier. You might think, enough of such tools already exist like all those UML diagram types or Flow Charts. But then, isn´t it strange, hardly any team is using them to design software? Or is that just due to a lack of education? I don´t think so. It´s a matter value/weight ratio: the current mental tools are too heavy weight compared to the value they deliver. So my conclusion is, we need lightweight tools to really be able to balance requirements. Software development is complex. We need guidance not to forget important aspects. That´s like with flying an airplane. Pilots don´t just jump in and take off for their destination. Yes, there are times when they are “flying by the seats of their pants”, when they are just experts doing thing intuitively. But most of the time they are going through honed practices called checklist. See “The Checklist Manifesto” for very enlightening details on this. Maybe then I should say it like this: We need more checklists for the complex businss of software development.[3] But that´s what software development mostly is about: changing software over an unknown period of time. It needs to be corrected in order to finally provide promised operations. It needs to be enhanced to provide ever more operations and qualities. All this without knowing when it´s going to stop. Probably never - until “maintainability” hits a wall when the technical debt is too large, the brownfield too deep. Software development is not a sprint, is not a marathon, not even an ultra marathon. Because to all this there is a foreseeable end. Software development is like continuously and foreever running… ? And sometimes I dare to think that costs could even decrease over time. Think of it: With each feature a software becomes richer in functionality. So with each additional feature the chance of there being already functionality helping its implementation increases. That should lead to less costs of feature X if it´s requested later than sooner. X requested later could stand on the shoulders of previous features. Alas, reality seems to be far from this despite 20+ years of admonishing developers to think in terms of reusability.[1] ? Please don´t get me wrong: I don´t want to bog down the “art” of software development with heavyweight practices and heaps of rules to follow. The framework we need should be lightweight. It should not stand in the way of delivering value to the customer. It´s purpose is even to make that easier by helping us to focus and decreasing waste and rework. ?

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• How to Run Low-Cost Minecraft on a Raspberry Pi for Block Building on the Cheap

  - by Jason Fitzpatrick

  We’ve shown you how to run your own blocktastic personal Minecraft server on a Windows/OSX box, but what if you crave something lighter weight, more energy efficient, and always ready for your friends? Read on as we turn a tiny Raspberry Pi machine into a low-cost Minecraft server you can leave on 24/7 for around a penny a day. Why Do I Want to Do This? There’s two aspects to this tutorial, running your own Minecraft server and specifically running that Minecraft server on a Raspberry Pi. Why would you want to run your own Minecraft server? It’s a really great way to extend and build upon the Minecraft play experience. You can leave the server running when you’re not playing so friends and family can join and continue building your world. You can mess around with game variables and introduce mods in a way that isn’t possible when you’re playing the stand-alone game. It also gives you the kind of control over your multiplayer experience that using public servers doesn’t, without incurring the cost of hosting a private server on a remote host. While running a Minecraft server on its own is appealing enough to a dedicated Minecraft fan, running it on the Raspberry Pi is even more appealing. The tiny little Pi uses so little resources that you can leave your Minecraft server running 24/7 for a couple bucks a year. Aside from the initial cost outlay of the Pi, an SD card, and a little bit of time setting it up, you’ll have an always-on Minecraft server at a monthly cost of around one gumball. What Do I Need? For this tutorial you’ll need a mix of hardware and software tools; aside from the actual Raspberry Pi and SD card, everything is free. 1 Raspberry Pi (preferably a 512MB model) 1 4GB+ SD card This tutorial assumes that you have already familiarized yourself with the Raspberry Pi and have installed a copy of the Debian-derivative Raspbian on the device. If you have not got your Pi up and running yet, don’t worry! Check out our guide, The HTG Guide to Getting Started with Raspberry Pi, to get up to speed. Optimizing Raspbian for the Minecraft Server Unlike other builds we’ve shared where you can layer multiple projects over one another (e.g. the Pi is more than powerful enough to serve as a weather/email indicator and a Google Cloud Print server at the same time) running a Minecraft server is a pretty intense operation for the little Pi and we’d strongly recommend dedicating the entire Pi to the process. Minecraft seems like a simple game, with all its blocky-ness and what not, but it’s actually a pretty complex game beneath the simple skin and required a lot of processing power. As such, we’re going to tweak the configuration file and other settings to optimize Rasbian for the job. The first thing you’ll need to do is dig into the Raspi-Config application to make a few minor changes. If you’re installing Raspbian fresh, wait for the last step (which is the Raspi-Config), if you already installed it, head to the terminal and type in “sudo raspi-config” to launch it again. One of the first and most important things we need to attend to is cranking up the overclock setting. We need all the power we can get to make our Minecraft experience enjoyable. In Raspi-Config, select option number 7 “Overclock”. Be prepared for some stern warnings about overclocking, but rest easy knowing that overclocking is directly supported by the Raspberry Pi foundation and has been included in the configuration options since late 2012. Once you’re in the actual selection screen, select “Turbo 1000MhHz”. Again, you’ll be warned that the degree of overclocking you’ve selected carries risks (specifically, potential corruption of the SD card, but no risk of actual hardware damage). Click OK and wait for the device to reset. Next, make sure you’re set to boot to the command prompt, not the desktop. Select number 3 “Enable Boot to Desktop/Scratch”  and make sure “Console Text console” is selected. Back at the Raspi-Config menu, select number 8 “Advanced Options’. There are two critical changes we need to make in here and one option change. First, the critical changes. Select A3 “Memory Split”: Change the amount of memory available to the GPU to 16MB (down from the default 64MB). Our Minecraft server is going to ruin in a GUI-less environment; there’s no reason to allocate any more than the bare minimum to the GPU. After selecting the GPU memory, you’ll be returned to the main menu. Select “Advanced Options” again and then select A4 “SSH”. Within the sub-menu, enable SSH. There is very little reason to keep this Pi connected to a monitor and keyboard, by enabling SSH we can remotely access the machine from anywhere on the network. Finally (and optionally) return again to the “Advanced Options” menu and select A2 “Hostname”. Here you can change your hostname from “raspberrypi” to a more fitting Minecraft name. We opted for the highly creative hostname “minecraft”, but feel free to spice it up a bit with whatever you feel like: creepertown, minecraft4life, or miner-box are all great minecraft server names. That’s it for the Raspbian configuration tab down to the bottom of the main screen and select “Finish” to reboot. After rebooting you can now SSH into your terminal, or continue working from the keyboard hooked up to your Pi (we strongly recommend switching over to SSH as it allows you to easily cut and paste the commands). If you’ve never used SSH before, check out how to use PuTTY with your Pi here. Installing Java on the Pi The Minecraft server runs on Java, so the first thing we need to do on our freshly configured Pi is install it. Log into your Pi via SSH and then, at the command prompt, enter the following command to make a directory for the installation: sudo mkdir /java/ Now we need to download the newest version of Java. At the time of this publication the newest release is the OCT 2013 update and the link/filename we use will reflect that. Please check for a more current version of the Linux ARMv6/7 Java release on the Java download page and update the link/filename accordingly when following our instructions. At the command prompt, enter the following command: sudo wget --no-check-certificate http://www.java.net/download/jdk8/archive/b111/binaries/jdk-8-ea-b111-linux-arm-vfp-hflt-09_oct_2013.tar.gz Once the download has finished successfully, enter the following command: sudo tar zxvf jdk-8-ea-b111-linux-arm-vfp-hflt-09_oct_2013.tar.gz -C /opt/ Fun fact: the /opt/ directory name scheme is a remnant of early Unix design wherein the /opt/ directory was for “optional” software installed after the main operating system; it was the /Program Files/ of the Unix world. After the file has finished extracting, enter: sudo /opt/jdk1.8.0/bin/java -version This command will return the version number of your new Java installation like so: java version "1.8.0-ea" Java(TM) SE Runtime Environment (build 1.8.0-ea-b111) Java HotSpot(TM) Client VM (build 25.0-b53, mixed mode) If you don’t see the above printout (or a variation thereof if you’re using a newer version of Java), try to extract the archive again. If you do see the readout, enter the following command to tidy up after yourself: sudo rm jdk-8-ea-b111-linux-arm-vfp-hflt-09_oct_2013.tar.gz At this point Java is installed and we’re ready to move onto installing our Minecraft server! Installing and Configuring the Minecraft Server Now that we have a foundation for our Minecraft server, it’s time to install the part that matter. We’ll be using SpigotMC a lightweight and stable Minecraft server build that works wonderfully on the Pi. First, grab a copy of the the code with the following command: sudo wget http://ci.md-5.net/job/Spigot/lastSuccessfulBuild/artifact/Spigot-Server/target/spigot.jar This link should remain stable over time, as it points directly to the most current stable release of Spigot, but if you have any issues you can always reference the SpigotMC download page here. After the download finishes successfully, enter the following command: sudo /opt/jdk1.8.0/bin/java -Xms256M -Xmx496M -jar /home/pi/spigot.jar nogui Note: if you’re running the command on a 256MB Pi change the 256 and 496 in the above command to 128 and 256, respectively. Your server will launch and a flurry of on-screen activity will follow. Be prepared to wait around 3-6 minutes or so for the process of setting up the server and generating the map to finish. Future startups will take much less time, around 20-30 seconds. Note: If at any point during the configuration or play process things get really weird (e.g. your new Minecraft server freaks out and starts spawning you in the Nether and killing you instantly), use the “stop” command at the command prompt to gracefully shutdown the server and let you restart and troubleshoot it. After the process has finished, head over to the computer you normally play Minecraft on, fire it up, and click on Multiplayer. You should see your server: If your world doesn’t popup immediately during the network scan, hit the Add button and manually enter the address of your Pi. Once you connect to the server, you’ll see the status change in the server status window: According to the server, we’re in game. According to the actual Minecraft app, we’re also in game but it’s the middle of the night in survival mode: Boo! Spawning in the dead of night, weaponless and without shelter is no way to start things. No worries though, we need to do some more configuration; no time to sit around and get shot at by skeletons. Besides, if you try and play it without some configuration tweaks first, you’ll likely find it quite unstable. We’re just here to confirm the server is up, running, and accepting incoming connections. Once we’ve confirmed the server is running and connectable (albeit not very playable yet), it’s time to shut down the server. Via the server console, enter the command “stop” to shut everything down. When you’re returned to the command prompt, enter the following command: sudo nano server.properties When the configuration file opens up, make the following changes (or just cut and paste our config file minus the first two lines with the name and date stamp): #Minecraft server properties #Thu Oct 17 22:53:51 UTC 2013 generator-settings= #Default is true, toggle to false allow-nether=false level-name=world enable-query=false allow-flight=false server-port=25565 level-type=DEFAULT enable-rcon=false force-gamemode=false level-seed= server-ip= max-build-height=256 spawn-npcs=true white-list=false spawn-animals=true texture-pack= snooper-enabled=true hardcore=false online-mode=true pvp=true difficulty=1 player-idle-timeout=0 gamemode=0 #Default 20; you only need to lower this if you're running #a public server and worried about loads. max-players=20 spawn-monsters=true #Default is 10, 3-5 ideal for Pi view-distance=5 generate-structures=true spawn-protection=16 motd=A Minecraft Server In the server status window, seen through your SSH connection to the pi, enter the following command to give yourself operator status on your Minecraft server (so that you can use more powerful commands in game, without always returning to the server status window). op [your minecraft nickname] At this point things are looking better but we still have a little tweaking to do before the server is really enjoyable. To that end, let’s install some plugins. The first plugin, and the one you should install above all others, is NoSpawnChunks. To install the plugin, first visit the NoSpawnChunks webpage and grab the download link for the most current version. As of this writing the current release is v0.3. Back at the command prompt (the command prompt of your Pi, not the server console–if your server is still active shut it down) enter the following commands: cd /home/pi/plugins sudo wget http://dev.bukkit.org/media/files/586/974/NoSpawnChunks.jar Next, visit the ClearLag plugin page, and grab the latest link (as of this tutorial, it’s v2.6.0). Enter the following at the command prompt: sudo wget http://dev.bukkit.org/media/files/743/213/Clearlag.jar Because the files aren’t compressed in a .ZIP or similar container, that’s all there is to it: the plugins are parked in the plugin directory. (Remember this for future plugin downloads, the file needs to be whateverplugin.jar, so if it’s compressed you need to uncompress it in the plugin directory.) Resart the server: sudo /opt/jdk1.8.0/bin/java -Xms256M -Xmx496M -jar /home/pi/spigot.jar nogui Be prepared for a slightly longer startup time (closer to the 3-6 minutes and much longer than the 30 seconds you just experienced) as the plugins affect the world map and need a minute to massage everything. After the spawn process finishes, type the following at the server console: plugins This lists all the plugins currently active on the server. You should see something like this: If the plugins aren’t loaded, you may need to stop and restart the server. After confirming your plugins are loaded, go ahead and join the game. You should notice significantly snappier play. In addition, you’ll get occasional messages from the plugins indicating they are active, as seen below: At this point Java is installed, the server is installed, and we’ve tweaked our settings for for the Pi.  It’s time to start building with friends!     

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