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• Communication between state machines with hidden transitions

  - by slartibartfast

  The question emerged for me in embedded programming but I think it can be applied to quite a number of general networking situations e.g. when a communication partner fails. Assume we have an application logic (a program) running on a computer and a gadget connected to that computer via e.g. a serial interface like RS232. The gadget has a red/green/blue LED and a button which disables the LED. The LEDs color can be driven by software commands over the serial interface and the state (red/green/blue/off) is read back and causes a reaction in the application logic. Asynchronous behaviour of the application logic with regard to the LED color down to a certain delay (depending on the execution cycle of the application) is tolerated. What we essentially have is a resource (the LED) which can not be reserved and handled atomically by software because the (organic) user can at any time press the button to interfere/break the software attempt to switch the LED color. Stripping this example from its physical outfit I dare to say that we have two communicating state machines A (application logic) and G (gadget) where G executes state changes unbeknownst to A (and also the other way round, but this is not significant in our example) and only A can be modified at a reasonable price. A needs to see the reaction and state of G in one piece of information which may be (slightly) outdated but not inconsistent with respect to the short time window when this information was generated on the side of G. What I am looking for is a concise method to handle such a situation in embedded software (i.e. no layer/framework like CORBA etc. available). A programming technique which is able to map the complete behaviour of both participants on classical interfaces of a classical programming language (C in this case). To complicate matters (or rather, to generalize), a simple high frequency communication cycle of A to G and back (IOW: A is rapidly polling G) is out of focus because of technical restrictions (delay of serial com, A not always active, etc.). What I currently see as a general solution is: the application logic A as one thread of execution an adapter object (proxy) PG (presenting G inside the computer), together with the serial driver as another thread a communication object between the two (A and PG) which is transactionally safe to exchange The two execution contexts (threads) on the computer may be multi-core or just interrupt driven or tasks in an RTOS. The com object contains the following data: suspected state (written by A): effectively a member of the power set of states in G (in our case: red, green, blue, off, red_or_green, red_or_blue, red_or_off...etc.) command data (written by A): test_if_off, switch_to_red, switch_to_green, switch_to_blue operation status (written by PG): operation_pending, success, wrong_state, link_broken new state (written by PG): red, green, blue, off The idea of the com object is that A writes whichever (set of) state it thinks G is in, together with a command. (Example: suspected state="red_or_green", command: "switch_to_blue") Notice that the commands issued by A will not work if the user has switched off the LED and A needs to know this. PG will pick up such a com object and try to send the command to G, receive its answer (or a timeout) and set the operation status and new state accordingly. A will take back the oject once it is no longer at operation_pending and can react to the outcome. The com object could be separated of course (into two objects, one for each direction) but I think it is convenient in nearly all instances to have the command close to the result. I would like to have major flaws pointed out or hear an entirely different view on such a situation.

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• Indexed view deadlocking

  - by Dave Ballantyne

  Deadlocks can be a really tricky thing to track down the root cause of.  There are lots of articles on the subject of tracking down deadlocks, but seldom do I find that in a production system that the cause is as straightforward.  That being said,  deadlocks are always caused by process A needs a resource that process B has locked and process B has a resource that process A needs.  There may be a longer chain of processes involved, but that is the basic premise. Here is one such (much simplified) scenario that was at first non-obvious to its cause: The system has two tables,  Products and Stock.  The Products table holds the description and prices of a product whilst Stock records the current stock level. USE tempdb GO CREATE TABLE Product ( ProductID INTEGER IDENTITY PRIMARY KEY, ProductName VARCHAR(255) NOT NULL, Price MONEY NOT NULL ) GO CREATE TABLE Stock ( ProductId INTEGER PRIMARY KEY, StockLevel INTEGER NOT NULL ) GO INSERT INTO Product SELECT TOP(1000) CAST(NEWID() AS VARCHAR(255)), ABS(CAST(CAST(NEWID() AS VARBINARY(255)) AS INTEGER))%100 FROM sys.columns a CROSS JOIN sys.columns b GO INSERT INTO Stock SELECT ProductID,ABS(CAST(CAST(NEWID() AS VARBINARY(255)) AS INTEGER))%100 FROM Product There is a single stored procedure of GetStock: Create Procedure GetStock as SELECT Product.ProductID,Product.ProductName FROM dbo.Product join dbo.Stock on Stock.ProductId = Product.ProductID where Stock.StockLevel <> 0 Analysis of the system showed that this procedure was causing a performance overhead and as reads of this data was many times more than writes,  an indexed view was created to lower the overhead. CREATE VIEW vwActiveStock With schemabinding AS SELECT Product.ProductID,Product.ProductName FROM dbo.Product join dbo.Stock on Stock.ProductId = Product.ProductID where Stock.StockLevel <> 0 go CREATE UNIQUE CLUSTERED INDEX PKvwActiveStock on vwActiveStock(ProductID) This worked perfectly, performance was improved, the team name was cheered to the rafters and beers all round.  Then, after a while, something else happened… The system updating the data changed,  The update pattern of both the Stock update and the Product update used to be: BEGIN TRAN UPDATE... COMMIT BEGIN TRAN UPDATE... COMMIT BEGIN TRAN UPDATE... COMMIT It changed to: BEGIN TRAN UPDATE... UPDATE... UPDATE... COMMIT Nothing that would raise an eyebrow in even the closest of code reviews.  But after this change we saw deadlocks occuring. You can reproduce this by opening two sessions. In session 1 begin transaction Update Product set ProductName ='Test' where ProductID = 998 Then in session 2 begin transaction Update Stock set Stocklevel = 5 where ProductID = 999 Update Stock set Stocklevel = 5 where ProductID = 998 Hop back to session 1 and.. Update Product set ProductName ='Test' where ProductID = 999 Looking at the deadlock graphs we could see the contention was between two processes, one updating stock and the other updating product, but we knew that all the processes do to the tables is update them.  Period.  There are separate processes that handle the update of stock and product and never the twain shall meet, no reason why one should be requiring data from the other.  Then it struck us,  AH the indexed view. Naturally, when you make an update to any table involved in a indexed view, the view has to be updated.  When this happens, the data in all the tables have to be read, so that explains our deadlocks.  The data from stock is read when you update product and vice-versa. The fix, once you understand the problem fully, is pretty simple, the apps did not guarantee the order in which data was updated.  Luckily it was a relatively simple fix to order the updates and deadlocks went away.  Note, that there is still a *slight* risk of a deadlock occurring, if both a stock update and product update occur at *exactly* the same time.

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• C++ property system interface for game editors (reflection system)

  - by Cristopher Ismael Sosa Abarca

  I have designed an reusable game engine for an project, and their functionality is like this: Is a completely scripted game engine instead of the usual scripting languages as Lua or Python, this uses Runtime-Compiled C++, and an modified version of Cistron (an component-based programming framework).to be compatible with Runtime-Compiled C++ and so on. Using the typical GameObject and Component classes of the Component-based design pattern, is serializable via JSON, BSON or Binary useful for selecting which objects will be loaded the next time. The main problem: We want to use our custom GameObjects and their components properties in our level editor, before used hardcoded functions to access GameObject base class virtual functions from the derived ones, if do you want to modify an property specifically from that class you need inside into the code, this situation happens too with the derived classes of Component class, in little projects there's no problem but for larger projects becomes tedious, lengthy and error-prone. I've researched a lot to find a solution without luck, i tried with the Ogitor's property system (since our engine is Ogre-based) but we find it inappropiate for the component-based design and it's limited only for the Ogre classes and can lead to performance overhead, and we tried some code we find in the Internet we tested it and worked a little but we considered the macro and lambda abuse too horrible take a look (some code omitted): IWE_IMPLEMENT_PROP_BEGIN(CBaseEntity) IWE_PROP_LEVEL_BEGIN("Editor"); IWE_PROP_INT_S("Id", "Internal id", m_nEntID, [](int n) {}, true); IWE_PROP_LEVEL_END(); IWE_PROP_LEVEL_BEGIN("Entity"); IWE_PROP_STRING_S("Mesh", "Mesh used for this entity", m_pModelName, [pInst](const std::string& sModelName) { pInst->m_stackMemUndoType.push(ENT_MEM_MESH); pInst->m_stackMemUndoStr.push(pInst->getModelName()); pInst->setModel(sModelName, false); pInst->saveState(); }, false); IWE_PROP_VECTOR3_S("Position", m_vecPosition, [pInst](float fX, float fY, float fZ) { pInst->m_stackMemUndoType.push(ENT_MEM_POSITION); pInst->m_stackMemUndoVec3.push(pInst->getPosition()); pInst->saveState(); pInst->m_vecPosition.Get()[0] = fX; pInst->m_vecPosition.Get()[1] = fY; pInst->m_vecPosition.Get()[2] = fZ; pInst->setPosition(pInst->m_vecPosition); }, false); IWE_PROP_QUATERNION_S("Orientation (Quat)", m_quatOrientation, [pInst](float fW, float fX, float fY, float fZ) { pInst->m_stackMemUndoType.push(ENT_MEM_ROTATE); pInst->m_stackMemUndoQuat.push(pInst->getOrientation()); pInst->saveState(); pInst->m_quatOrientation.Get()[0] = fW; pInst->m_quatOrientation.Get()[1] = fX; pInst->m_quatOrientation.Get()[2] = fY; pInst->m_quatOrientation.Get()[3] = fZ; pInst->setOrientation(pInst->m_quatOrientation); }, false); IWE_PROP_LEVEL_END(); IWE_IMPLEMENT_PROP_END() We are finding an simplified way to this, without leading confusing the programmers, (will be released to the public) i find ways to achieve this but they are only available for the common scripting as Lua or editors using C#. also too portable, we can write "wrappers" for different GUI toolkits as Qt or GTK, also i'm thinking to using Boost.Wave to get additional macro functionality without creating my own compiler. The properties designed to use in the editor they are removed in the game since the save file contains their data and loads it using an simple 'load' function to reduce unnecessary code bloat may will be useful if some GameObject property wants to be hidden instead. In summary, there's a way to implement an reflection(property) system for a level editor based in properties from derived classes? Also we can use C++11 and Boost (restricted only to Wave and PropertyTree)

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• Method flags as arguments or as member variables?

  - by Martin

  I think the title "Method flags as arguments or as member variables?" may be suboptimal, but as I'm missing any better terminology atm., here goes: I'm currently trying to get my head around the problem of whether flags for a given class (private) method should be passed as function arguments or via member variable and/or whether there is some pattern or name that covers this aspect and/or whether this hints at some other design problems. By example (language could be C++, Java, C#, doesn't really matter IMHO): class Thingamajig { private ResultType DoInternalStuff(FlagType calcSelect) { ResultType res; for (... some loop condition ...) { ... if (calcSelect == typeA) { ... } else if (calcSelect == typeX) { ... } else if ... } ... return res; } private void InteralStuffInvoker(FlagType calcSelect) { ... DoInternalStuff(calcSelect); ... } public void DoThisStuff() { ... some code ... InternalStuffInvoker(typeA); ... some more code ... } public ResultType DoThatStuff() { ... some code ... ResultType x = DoInternalStuff(typeX); ... some more code ... further process x ... return x; } } What we see above is that the method InternalStuffInvoker takes an argument that is not used inside this function at all but is only forwarded to the other private method DoInternalStuff. (Where DoInternalStuffwill be used privately at other places in this class, e.g. in the DoThatStuff (public) method.) An alternative solution would be to add a member variable that carries this information: class Thingamajig { private ResultType DoInternalStuff() { ResultType res; for (... some loop condition ...) { ... if (m_calcSelect == typeA) { ... } ... } ... return res; } private void InteralStuffInvoker() { ... DoInternalStuff(); ... } public void DoThisStuff() { ... some code ... m_calcSelect = typeA; InternalStuffInvoker(); ... some more code ... } public ResultType DoThatStuff() { ... some code ... m_calcSelect = typeX; ResultType x = DoInternalStuff(); ... some more code ... further process x ... return x; } } Especially for deep call chains where the selector-flag for the inner method is selected outside, using a member variable can make the intermediate functions cleaner, as they don't need to carry a pass-through parameter. On the other hand, this member variable isn't really representing any object state (as it's neither set nor available outside), but is really a hidden additional argument for the "inner" private method. What are the pros and cons of each approach?

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• Designing status management for a file processing module

  - by bot

  The background One of the functionality of a product that I am currently working on is to process a set of compressed files ( containing XML files ) that will be made available at a fixed location periodically (local or remote location - doesn't really matter for now) and dump the contents of each XML file in a database. I have taken care of the design for a generic parsing module that should be able to accommodate the parsing of any file type as I have explained in my question linked below. There is no need to take a look at the following link to answer my question but it would definitely provide a better context to the problem Generic file parser design in Java using the Strategy pattern The Goal I want to be able to keep a track of the status of each XML file and the status of each compressed file containing the XML files. I can probably have different statuses defined for the XML files such as NEW, PROCESSING, LOADING, COMPLETE or FAILED. I can derive the status of a compressed file based on the status of the XML files within the compressed file. e.g status of the compressed file is COMPLETE if no XML file inside the compressed file is in a FAILED state or status of the compressed file is FAILED if the status of at-least one XML file inside the compressed file is FAILED. A possible solution The Model I need to maintain the status of each XML file and the compressed file. I will have to define some POJOs for holding the information about an XML file as shown below. Note that there is no need to store the status of a compressed file as the status of a compressed file can be derived from the status of its XML files. public class FileInformation { private String compressedFileName; private String xmlFileName; private long lastModifiedDate; private int status; public FileInformation(final String compressedFileName, final String xmlFileName, final long lastModified, final int status) { this.compressedFileName = compressedFileName; this.xmlFileName = xmlFileName; this.lastModifiedDate = lastModified; this.status = status; } } I can then have a class called StatusManager that aggregates a Map of FileInformation instances and provides me the status of a given file at any given time in the lifetime of the appliciation as shown below : public class StatusManager { private Map<String,FileInformation> processingMap = new HashMap<String,FileInformation>(); public void add(FileInformation fileInformation) { fileInformation.setStatus(0); // 0 will indicates that the file is in NEW state. 1 will indicate that the file is in process and so on.. processingMap.put(fileInformation.getXmlFileName(),fileInformation); } public void update(String filename,int status) { FileInformation fileInformation = processingMap.get(filename); fileInformation.setStatus(status); } } That takes care of the model for the sake of explanation. So whats my question? Edited after comments from Loki and answer from Eric : - I would like to know if there are any existing design patterns that I can refer to while coming up with a design. I would also like to know how I should go about designing the status management classes. I am more interested in understanding how I can model the status management classes. I am not interested in how other components are going to be updated about a change in status at the moment as suggested by Eric.

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• Friday Tips #6, Part 1

  - by Chris Kawalek

  We have a two parter this week, with this post focusing on desktop virtualization and the next one on server virtualization. Question: Why would I use the Oracle Secure Global Desktop Secure Gateway? Answer by Rick Butland, Principal Sales Consultant, Oracle Desktop Virtualization: Well, for the benefit of those who might not be familiar with client connections in Oracle Secure Global Desktop (SGD), let me back up and briefly explain. An SGD client connects to an SGD server using two distinct protocols, which, by default, require two distinct TCP ports. The first is the HTTP protocol, used by the web browser to connect to the SGD webserver on TCP port 80, or if secure connections are enabled (SSL/TLS), then TCP port 443, commonly identified as the "HTTPS" port, that is, "SSL encrypted HTTP." The second protocol from the client to the server is the Adaptive Internet Protocol, or AIP, which is used for displaying applications, transferring drive mapping data, print jobs, and so on. By default, AIP uses the TCP port 3104, or port 5307 when SSL is enabled. When SGD clients need to access SGD over a firewall, the ports that AIP requires are typically "closed"; and most administrators are reluctant, to put it mildly, to change their firewall configurations to allow AIP traffic on 3144/5307.   To avoid this problem, SGD introduced "Firewall Forwarding", a technique where, in effect, both http and AIP traffic are "multiplexed" onto a single "well-known" TCP port, that is port 443, the https port.  This is also known as single-port firewall traversal.  This technique takes advantage of the fact that, as a "well-known service", port 443 is usually "open",   allowing (encrypted) traffic to pass. At the target SGD server, the two protocols are de-multiplexed and routed appropriately. The Secure Gateway was developed in response to requirements from customers for SGD to support multi-stage DMZ's, and to avoid exposing SGD servers and the information they contain directly to connections from the Internet. The Secure Gateway acts as a reverse-proxy in the first-tier of the DMZ, accepting, authenticating, and terminating incoming client connections, and then re-encrypting the connections, and proxying them, routing them on to SGD servers, deeper in the network. The client no longer needs to know the name/IP address of the SGD servers in their network, they connect to the gateway, only. The gateway takes care of those internal network details.     The Secure Gateway supports the same "single-port firewall" capability as does "Firewall Forwarding", but offers the additional advantage of load-balancing incoming client connections amongst SGD array members, which could be cumbersome without a forward-deployed secure gateway. Load-balancing weights and policies can be monitored and tuned using the "Balancer Manager" application, and Apache mod_proxy_balancer directives.   Going forward, our architects recommend the use of the Secure Gateway over "Firewall Forwarding" for single-port firewall traversal, due to its architectural advantages, its greater flexibility and enhanced features.  Finally, it should be noted that the Secure Gateway is not separately priced; any licensed SGD customer may use the Secure Gateway component at no additional cost.   For more information, see the "Secure Gateway Administrator's Guide".

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• Lead, Follow, or Get out of the way

  - by Daniel Moth

  This is one of the sayings (attributed to Thomas Paine) that totally resonated with me from the first time I heard it, which was only 3 years ago during some training course at work: "Lead, Follow, or Get out of the way" You'll find many books with this title and you'll find it quoted by politicians and other leaders in various countries at various times... the quote is open to interpretation and works on many levels. To set the tone of what this means to me, I'll use a simple micro example: In any given conversation, you are either leading it or following it, at different times/snapshots of the conversation. If you are not willing or able to lead it, and you are not willing or able to follow it, then you should depart. The bad alternative which this guidance encourages you NOT to do is to stick around and obstruct progress by not following, not leading, and simply complaining or trying to derail the discussion in no particular direction. The same pattern applies at your position/role at work. Either follow your management/leadership team, or try to lead them to what you think is a better place, or change jobs. Don't stick around complaining about the direction things are going, while not actively trying to either change things or make peace with it. In the previous paragraph you can replace the word "your management" with "the people reporting to you" and the guidance still holds. Either lead your direct reports to where you think they should go, or follow their lead, or change jobs. Complaining about folks not taking direction while doing nothing is not a maintainable state. To me this quote is not about a permanent state, it is not about some people always leading and some always following: It is about a role/hat that anybody can play/wear at any given moment. One minute I am leading you, the next I am following you, and the next we are both following someone else and so on... When there is disagreement, debate the different directions for as long as it takes for you to be comfortable that you can either follow or lead. If you don't become comfortable with either of those, get out of the way. Something to remember is that it is impossible to learn how to lead well, without learning how to follow well (probably deserves its own blog entry)... Things go wrong when someone thinks that they must always be leading, or when everybody wants to follow and nobody steps up to lead... Things go wrong when more than one person wants to lead and they don't try to reach agreement on a shared direction, stubbornly sticking to their guns pulling the rest of the team in multiple directions... Things go wrong when more than one person wants to lead and after numerous and lengthy discussions, none of them decides to follow or get out of the way... Things go wrong when people don't want to lead, don't want to follow, and insist on sticking around... While there are a few ways things that can go wrong as enumerated in the previous paragraph, the most common one in my experience is the last one I mentioned. You'll recognize these folks as the ones that always complain about everything that is wrong with their company/product but do nothing about it. Every time you hear someone giving feedback on how something is wrong or suboptimal, ask them "So now that you identified the problem, what do you think the solution is and what are you doing to drive us to that solution?" The next time things start going wrong, step up and remind everyone: Lead, Follow, or Get out of the way. For more perspectives, and for input to help you form your own interpretation, search the web for this phrase to see in what contexts it is being used (bing, google). Finally, regardless of your political views, I hope you can appreciate if only as an example this perspective of someone leading by actually getting out of the way. Comments about this post by Daniel Moth welcome at the original blog.

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• Texture errors in CubeMap

  - by shade4159

  I am trying to apply this texture as a cubemap. This is my result: Clearly I am doing something with my texture coordinates, but I cannot for the life of me figure out what. I don't even see a pattern to the texture fragments. They just seem like a jumble of different faces. Can anyone shed some light on this? Vertex shader: #version 400 in vec4 vPosition; in vec3 inTexCoord; smooth out vec3 texCoord; uniform mat4 projMatrix; void main() { texCoord = inTexCoord; gl_Position = projMatrix * vPosition; } My fragment shader: #version 400 smooth in vec3 texCoord; out vec4 fColor; uniform samplerCube textures void main() { fColor = texture(textures,texCoord); } Vertices of cube: point4 worldVerts[8] = { vec4( 15, 15, 15, 1 ), vec4( -15, 15, 15, 1 ), vec4( -15, 15, -15, 1 ), vec4( 15, 15, -15, 1 ), vec4( -15, -15, 15, 1 ), vec4( 15, -15, 15, 1 ), vec4( 15, -15, -15, 1 ), vec4( -15, -15, -15, 1 ) }; Cube rendering: void worldCube(point4* verts, int& Index, point4* points, vec3* texVerts) { quadInv( verts[0], verts[1], verts[2], verts[3], 1, Index, points, texVerts); quadInv( verts[6], verts[3], verts[2], verts[7], 2, Index, points, texVerts); quadInv( verts[4], verts[5], verts[6], verts[7], 3, Index, points, texVerts); quadInv( verts[4], verts[1], verts[0], verts[5], 4, Index, points, texVerts); quadInv( verts[5], verts[0], verts[3], verts[6], 5, Index, points, texVerts); quadInv( verts[4], verts[7], verts[2], verts[1], 6, Index, points, texVerts); } Backface function (since this is the inside of the cube): void quadInv( const point4& a, const point4& b, const point4& c, const point4& d , int& Index, point4* points, vec3* texVerts) { quad( a, d, c, b, Index, points, texVerts, a.to_3(), b.to_3(), c.to_3(), d.to_3()); } And the quad drawing function: void quad( const point4& a, const point4& b, const point4& c, const point4& d, int& Index, point4* points, vec3* texVerts, const vec3& tex_a, const vec3& tex_b, const vec3& tex_c, const vec3& tex_d) { texVerts[Index] = tex_a.normalized(); points[Index] = a; Index++; texVerts[Index] = tex_b.normalized(); points[Index] = b; Index++; texVerts[Index] = tex_c.normalized(); points[Index] = c; Index++; texVerts[Index] = tex_a.normalized(); points[Index] = a; Index++; texVerts[Index] = tex_c.normalized(); points[Index] = c; Index++; texVerts[Index] = tex_d.normalized(); points[Index] = d; Index++; } Edit: I forgot to mention, in the image, the camera is pointed directly at the back face of the cube. You can kind of see the diagonals leading out of the corners, if you squint.

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• A more elegant way of embedding a SOAP security header in Silverlight 4

  - by Your DisplayName here!

  The current situation with Silverlight is, that there is no support for the WCF federation binding. This means that all security token related interactions have to be done manually. Requesting the token from an STS is not really the bad part, sending it along with outgoing SOAP messages is what’s a little annoying. So far you had to wrap all calls on the channel in an OperationContextScope wrapping an IContextChannel. This “programming model” was a little disruptive (in addition to all the async stuff that you are forced to do). It seems that starting with SL4 there is more support for traditional WCF extensibility points – especially IEndpointBehavior, IClientMessageInspector. I never read somewhere that these are new features in SL4 – but I am pretty sure they did not exist in SL3. With the above mentioned interfaces at my disposal, I thought I have another go at embedding a security header – and yeah – I managed to make the code much prettier (and much less bizarre). Here’s the code for the behavior/inspector: public class IssuedTokenHeaderInspector : IClientMessageInspector {     RequestSecurityTokenResponse _rstr;       public IssuedTokenHeaderInspector(RequestSecurityTokenResponse rstr)     {         _rstr = rstr;     }       public void AfterReceiveReply(ref Message reply, object correlationState)     { }       public object BeforeSendRequest(ref Message request, IClientChannel channel)     {         request.Headers.Add(new IssuedTokenHeader(_rstr));                  return null;     } }   public class IssuedTokenHeaderBehavior : IEndpointBehavior {     RequestSecurityTokenResponse _rstr;       public IssuedTokenHeaderBehavior(RequestSecurityTokenResponse rstr)     {         if (rstr == null)         {             throw new ArgumentNullException();         }           _rstr = rstr;     }       public void ApplyClientBehavior(       ServiceEndpoint endpoint, ClientRuntime clientRuntime)     {         clientRuntime.MessageInspectors.Add(new IssuedTokenHeaderInspector(_rstr));     }       // rest omitted } This allows to set up a proxy with an issued token header and you don’t have to worry anymore with embedding the header manually with every call: var client = GetWSTrustClient();   var rst = new RequestSecurityToken(WSTrust13Constants.KeyTypes.Symmetric) {     AppliesTo = new EndpointAddress("https://rp/") };   client.IssueCompleted += (s, args) => {     _proxy = new StarterServiceContractClient();     _proxy.Endpoint.Behaviors.Add(new IssuedTokenHeaderBehavior(args.Result));   };   client.IssueAsync(rst); Since SL4 also support the IExtension<T> interface, you can also combine this with Nicholas Allen’s AutoHeaderExtension.

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• Know your Data Lineage

  - by Simon Elliston Ball

  An academic paper without the footnotes isn’t an academic paper. Journalists wouldn’t base a news article on facts that they can’t verify. So why would anyone publish reports without being able to say where the data has come from and be confident of its quality, in other words, without knowing its lineage. (sometimes referred to as ‘provenance’ or ‘pedigree’) The number and variety of data sources, both traditional and new, increases inexorably. Data comes clean or dirty, processed or raw, unimpeachable or entirely fabricated. On its journey to our report, from its source, the data can travel through a network of interconnected pipes, passing through numerous distinct systems, each managed by different people. At each point along the pipeline, it can be changed, filtered, aggregated and combined. When the data finally emerges, how can we be sure that it is right? How can we be certain that no part of the data collection was based on incorrect assumptions, that key data points haven’t been left out, or that the sources are good? Even when we’re using data science to give us an approximate or probable answer, we cannot have any confidence in the results without confidence in the data from which it came. You need to know what has been done to your data, where it came from, and who is responsible for each stage of the analysis. This information represents your data lineage; it is your stack-trace. If you’re an analyst, suspicious of a number, it tells you why the number is there and how it got there. If you’re a developer, working on a pipeline, it provides the context you need to track down the bug. If you’re a manager, or an auditor, it lets you know the right things are being done. Lineage tracking is part of good data governance. Most audit and lineage systems require you to buy into their whole structure. If you are using Hadoop for your data storage and processing, then tools like Falcon allow you to track lineage, as long as you are using Falcon to write and run the pipeline. It can mean learning a new way of running your jobs (or using some sort of proxy), and even a distinct way of writing your queries. Other Hadoop tools provide a lot of operational and audit information, spread throughout the many logs produced by Hive, Sqoop, MapReduce and all the various moving parts that make up the eco-system. To get a full picture of what’s going on in your Hadoop system you need to capture both Falcon lineage and the data-exhaust of other tools that Falcon can’t orchestrate. However, the problem is bigger even that that. Often, Hadoop is just one piece in a larger processing workflow. The next step of the challenge is how you bind together the lineage metadata describing what happened before and after Hadoop, where ‘after’ could be  a data analysis environment like R, an application, or even directly into an end-user tool such as Tableau or Excel. One possibility is to push as much as you can of your key analytics into Hadoop, but would you give up the power, and familiarity of your existing tools in return for a reliable way of tracking lineage? Lineage and auditing should work consistently, automatically and quietly, allowing users to access their data with any tool they require to use. The real solution, therefore, is to create a consistent method by which to bring lineage data from these data various disparate sources into the data analysis platform that you use, rather than being forced to use the tool that manages the pipeline for the lineage and a different tool for the data analysis. The key is to keep your logs, keep your audit data, from every source, bring them together and use the data analysis tools to trace the paths from raw data to the answer that data analysis provides.

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• Setup and configure a MVC4 project for Cloud Service(web role) and SQL Azure

  - by MagnusKarlsson

  I aim at keeping this blog post updated and add related posts to it. Since there are a lot of these out there I link to others that has done kind of the same before me, kind of a blog-DRY pattern that I'm aiming for. I also keep all mistakes and misconceptions for others to see. As an example; if I hit a stacktrace I will google it if I don't directly figure out the reason for it. I will then probably take the most plausible result and try it out. If it fails because I misinterpreted the error I will not delete it from the log but keep it for future reference and for others to see. That way people that finds this blog can see multiple solutions for indexed stacktraces and I can better remember how to do stuff. To avoid my errors I recommend you to read through it all before going from start to finish.The steps:Setup project in VS2012. (msdn blog)Setup Azure Services (half of mpspartners.com blog)Setup connections strings and configuration files (msdn blog + notes)Export certificates.Create Azure package from vs2012 and deploy to staging (same steps as for production).Connections string error Set up the visual studio project:http://blogs.msdn.com/b/avkashchauhan/archive/2011/11/08/developing-asp-net-mvc4-based-windows-azure-web-role.aspx Then login in to Azure to setup the services:Stop following this guide at the "publish website" part since we'll be uploading a package.http://www.mpspartners.com/2012/09/ConfiguringandDeployinganMVC4applicationasaCloudServicewithAzureSQLandStorage/ When set up (connection strings for debug and release and all), follow this guide to set up the configuration files:http://msdn.microsoft.com/en-us/library/windowsazure/hh369931.aspxTrying to package our application at this step will generate the following warning:3>MvcWebRole1(0,0): warning WAT170: The configuration setting 'Microsoft.WindowsAzure.Plugins.Diagnostics.ConnectionString' is set up to use the local storage emulator for role 'MvcWebRole1' in configuration file 'ServiceConfiguration.Cloud.cscfg'. To access Windows Azure storage services, you must provide a valid Windows Azure storage connection string. Right click the web role under roles in solution manager and choose properties. Choose "Service configuration: Cloud". At "specify storage account credentials" we will copy/paste our account name and key from the Azure management platform.3.1 4. Right click Remote desktop Configuration and select certificate and export to file. We need to allow it in Portal manager.4.15 Now right click the cloud project and select package.5.1 Showing dialogue box. 5.2 Package success Now copy the path to the packaged file and go to management portal again. Click your web role and choose staging (or production). Upload. 5.3Tick the box about the single instance if that's what you want or you don't know what it means. Otherwise the following will happen (see image 4.6)5.4 Dialogue box When you have clicked the symbol for accept- button you will see the following screen with some green indicators down at the right corner. Click them if you want to see status.5.5 Information screen.5.6 "Failed to deploy application. The upload application has at least one role with only one instance. We recommend that you deploy at least two instances per role to ensure high availability in case one of the instances becomes unavailable. "To fix, go to step 5.4If you forgot to (or just didn't know you were supposed to) export your certificates. The following error will occur. Side note, the following thread suggests. To prevent: "Enable Remote Desktop for all roles" when right-clicking BIAB and choosing "Package". But in my case it was the not so present certificates. I fund the solution here.http://social.msdn.microsoft.com/Forums/en-US/dotnetstocktradersampleapplication/thread/0e94c2b5-463f-4209-86b9-fc257e0678cd5.75.8 Success! 5.9 Nice URL n' all. (More on that at another blog post).6. If you try to login and getWhen this error occurs many web sites suggest this is because you need:http://nuget.org/packages/Microsoft.AspNet.Providers.LocalDBOr : http://nuget.org/packages/Microsoft.AspNet.ProvidersBut it can also be that you don't have the correct setup for converting connectionstrings between your web.config to your debug.web.config(or release.web.config, whichever your using).Run as suggested in the "ordinary project in your solution. Go to the management portal and click update.

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• My shiny new gadget

  - by TechTwaddle

  About 3 months ago when I had tweeted (or twit?) that the HD7 could be my next phone I wasn’t a 100 percent sure, and when the HTC Mozart came out it was switch at first sight. I wanted to buy the Mozart mainly for three reasons; its unibody construction, smaller screen and the SLCD display. But now, holding a HD7 in my hand, I reminisce and think about how fate had its own plan. Too dramatic for a piece of gadget? Well, sort of, but seriously, this has been most exciting. So in short, I bought myself a HTC HD7 and am really loving it so far. Here are some pics (taken from my HD2 which now lies in a corner, crying),     Most of my day was spent setting up the device. Email accounts, Facebook, Marketplace etc. Since marketplace isn’t officially launched in India yet, my primary live id did not work. Whenever I tried launching marketplace it would say ‘marketplace is not currently supported in your country’. Searching the forums I found an easy work around. Just create a dummy live id with the country set to UK or US and log in to the device using this id. I was worried if the contacts and feeds from my primary live account would not be updated but that was not a problem. Adding another live account into the device does import your contacts, calendar and feeds from it. And that’s it, marketplace now works perfectly. I installed a few trial and free applications; haven’t checked if I can purchase apps though, will check that later and update this post. There is one issue I am still facing with the device, I can’t access the internet over GPRS. Windows Phone 7 only gives you the option to add an ‘APN’ and nothing else. Checking the connection settings on my HD2, I found out that there is also a proxy server I need to add to access GPRS, but so far I haven’t found a way to do that on WP7. Ideally HTC should have taken care of this, detect the operator and apply that operators settings on the device, but looks like that’s not happening. I also tried the ‘Connection Settings’ application that HTC bundled with the device, but it did nothing magical. If you’re reading this and know how to fix this problem please leave a comment. The next thing I did is install apps, a lot of apps. Read Engadget’s guide to essential apps for WP7. The apps and games I installed so far include Beezz (twitter app with push notifications), twitter (the official twitter app), Facebook, Youtube, NFS Undercover, Rocket Riot, Krashlander, Unite and the list goes on. All the apps run super smooth. The display looks fine indoors but I know it’s going to suck in bright sunlight. Anyhow, I am really impressed with what I’ve seen so far. I leave you with a few more photos. Have a great year ahead. Ciao!

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• Randomely loosing wireless connexion with Cubuntu 12.04

  - by statquant

  I am presently experiencing random disconnections from my wireless network. It looks like it is more and more frequent (however I have not seen any clear pattern). This is killing me... Here is some information that should help (from ubuntu forums). Thanks for reading Machine : Acer Aspire S3 statquant@euclide:~$ lsb_release -d Description: Ubuntu 12.04.1 LTS statquant@euclide:~$ uname -mr 3.2.0-33-generic x86_64 statquant@euclide:~$ sudo /etc/init.d/networking restart * Running /etc/init.d/networking restart is deprecated because it may not enable again some interfaces * Reconfiguring network interfaces... statquant@euclide:~$ lspci 02:00.0 Network controller: Atheros Communications Inc. AR9485 Wireless Network Adapter (rev 01) statquant@euclide:~$ lsusb Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub Bus 002 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub Bus 001 Device 002: ID 8087:0024 Intel Corp. Integrated Rate Matching Hub Bus 002 Device 002: ID 8087:0024 Intel Corp. Integrated Rate Matching Hub Bus 001 Device 004: ID 064e:c321 Suyin Corp. Bus 002 Device 003: ID 0bda:0129 Realtek Semiconductor Corp. statquant@euclide:~$ ifconfig wlan0 Link encap:Ethernet HWaddr 74:de:2b:dd:c4:78 inet addr:192.168.1.3 Bcast:192.168.1.255 Mask:255.255.255.0 inet6 addr: fe80::76de:2bff:fedd:c478/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:913 errors:0 dropped:0 overruns:0 frame:0 TX packets:802 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:873218 (873.2 KB) TX bytes:125826 (125.8 KB) statquant@euclide:~$ iwconfig wlan0 IEEE 802.11bgn ESSID:"Bbox-D646D1" Mode:Managed Frequency:2.437 GHz Access Point: 00:19:70:80:01:6C Bit Rate=65 Mb/s Tx-Power=16 dBm Retry long limit:7 RTS thr:off Fragment thr:off Power Management:on Link Quality=56/70 Signal level=-54 dBm Rx invalid nwid:0 Rx invalid crypt:0 Rx invalid frag:0 Tx excessive retries:0 Invalid misc:71 Missed beacon:0 statquant@euclide:~$ dmesg | grep "wlan" [ 17.495866] ADDRCONF(NETDEV_UP): wlan0: link is not ready [ 17.498950] ADDRCONF(NETDEV_UP): wlan0: link is not ready [ 20.072015] wlan0: authenticate with 00:19:70:80:01:6c (try 1) [ 20.269853] wlan0: authenticate with 00:19:70:80:01:6c (try 2) [ 20.272386] wlan0: authenticated [ 20.298682] wlan0: associate with 00:19:70:80:01:6c (try 1) [ 20.302321] wlan0: RX AssocResp from 00:19:70:80:01:6c (capab=0x431 status=0 aid=1) [ 20.302325] wlan0: associated [ 20.307307] ADDRCONF(NETDEV_CHANGE): wlan0: link becomes ready [ 30.402292] wlan0: no IPv6 routers present statquant@euclide:~$ sudo lshw -C network [sudo] password for statquant: *-network description: Wireless interface product: AR9485 Wireless Network Adapter vendor: Atheros Communications Inc. physical id: 0 bus info: pci@0000:02:00.0 logical name: wlan0 version: 01 serial: 74:de:2b:dd:c4:78 width: 64 bits clock: 33MHz capabilities: pm msi pciexpress bus_master cap_list rom ethernet physical wireless configuration: broadcast=yes driver=ath9k driverversion=3.2.0-33-generic firmware=N/A ip=192.168.1.3 latency=0 link=yes multicast=yes wireless=IEEE 802.11bgn resources: irq:17 memory:c0400000-c047ffff memory:afb00000-afb0ffff statquant@euclide:~$ iwlist scan wlan0 Scan completed : Cell 01 - Address: 00:19:70:80:01:6C Channel:6 Frequency:2.437 GHz (Channel 6) Quality=56/70 Signal level=-54 dBm Encryption key:on ESSID:"Bbox-D646D1" Bit Rates:1 Mb/s; 2 Mb/s; 5.5 Mb/s; 11 Mb/s; 6 Mb/s 9 Mb/s; 12 Mb/s; 18 Mb/s Bit Rates:24 Mb/s; 36 Mb/s; 48 Mb/s; 54 Mb/s Mode:Master Extra:tsf=000000125fb152bb Extra: Last beacon: 40020ms ago IE: Unknown: 000B42626F782D443634364431 IE: Unknown: 010882848B960C121824 IE: Unknown: 030106 IE: IEEE 802.11i/WPA2 Version 1 Group Cipher : TKIP Pairwise Ciphers (2) : CCMP TKIP Authentication Suites (1) : PSK IE: WPA Version 1 Group Cipher : TKIP Pairwise Ciphers (2) : CCMP TKIP Authentication Suites (1) : PSK IE: Unknown: 2A0100 IE: Unknown: 32043048606C IE: Unknown: DD180050F2020101820003A4000027A4000042435E0062322F00 IE: Unknown: 2D1A4C101BFF00000000000000000000000000000000000000000000 IE: Unknown: 3D1606080800000000000000000000000000000000000000 IE: Unknown: DD0900037F01010000FF7F IE: Unknown: DD0A00037F04010000000000 And... finally, please note that I did the following (after looking for fixes of similar problems), but unfortunately it did not work sudo modprobe -r iwlwifi sudo modprobe iwlwifi 11n_disable=1

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• C# 5 Async, Part 3: Preparing Existing code For Await

  - by Reed

  While the Visual Studio Async CTP provides a fantastic model for asynchronous programming, it requires code to be implemented in terms of Task and Task<T>.  The CTP adds support for Task-based asynchrony to the .NET Framework methods, and promises to have these implemented directly in the framework in the future.  However, existing code outside the framework will need to be converted to using the Task class prior to being usable via the CTP. Wrapping existing asynchronous code into a Task or Task<T> is, thankfully, fairly straightforward.  There are two main approaches to this. Code written using the Asynchronous Programming Model (APM) is very easy to convert to using Task<T>.  The TaskFactory class provides the tools to directly convert APM code into a method returning a Task<T>.  This is done via the FromAsync method.  This method takes the BeginOperation and EndOperation methods, as well as any parameters and state objects as arguments, and returns a Task<T> directly. For example, we could easily convert the WebRequest BeginGetResponse and EndGetResponse methods into a method which returns a Task<WebResponse> via: Task<WebResponse> task = Task.Factory .FromAsync<WebResponse>( request.BeginGetResponse, request.EndGetResponse, null); .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } Event-based Asynchronous Pattern (EAP) code can also be wrapped into a Task<T>, though this requires a bit more effort than the one line of code above.  This is handled via the TaskCompletionSource<T> class.  MSDN provides a detailed example of using this to wrap an EAP operation into a method returning Task<T>.  It demonstrates handling cancellation and exception handling as well as the basic operation of the asynchronous method itself. The basic form of this operation is typically: Task<YourResult> GetResultAsync() { var tcs = new TaskCompletionSource<YourResult>(); // Handle the event, and setup the task results... this.GetResultCompleted += (o,e) => { if (e.Error != null) tcs.TrySetException(e.Error); else if (e.Cancelled) tcs.TrySetCanceled(); else tcs.TrySetResult(e.Result); }; // Call the asynchronous method this.GetResult(); // Return the task from the TaskCompletionSource return tcs.Task; } We can easily use these methods to wrap our own code into a method that returns a Task<T>.  Existing libraries which cannot be edited can be extended via Extension methods.  The CTP uses this technique to add appropriate methods throughout the framework. The suggested naming for these methods is to define these methods as “Task<YourResult> YourClass.YourOperationAsync(…)”.  However, this naming often conflicts with the default naming of the EAP.  If this is the case, the CTP has standardized on using “Task<YourResult> YourClass.YourOperationTaskAsync(…)”. Once we’ve wrapped all of our existing code into operations that return Task<T>, we can begin investigating how the Async CTP can be used with our own code.

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• New Version 3.1 Endeca Information Discovery Now Available

  - by Mike.Hallett(at)Oracle-BI&EPM

  Normal 0 false false false EN-GB X-NONE X-NONE MicrosoftInternetExplorer4 Business User Self-Service Data Mash-up Analysis and Discovery integrated with OBI11g and Hadoop Oracle Endeca Information Discovery 3.1 (OEID) is a major release that incorporates significant new self-service discovery capabilities for business users, including agile data mashup, extended support for unstructured analytics, and an even tighter integration with Oracle BI.  · Self-Service Data Mashup and Discovery Dashboards: business users can combine information from multiple sources, including their own up-loaded spreadsheets, to conduct analysis on the complete set.  Creating discovery dashboards has been made even easier by intuitive drag-and drop layouts and wizard-based configuration.  Business users can now build new discovery applications in minutes, without depending on IT. · Enhanced Integration with Oracle BI: OEID 3.1 enhances its’ native integration with Oracle Business Intelligence Foundation. Business users can now incorporate information from trusted BI warehouses, leveraging dimensions and attributes defined in Oracle’s Common Enterprise Information Model, but evolve them based on the varying day-to-day demands and requirements that they personally manage. · Deep Unstructured Analysis: business users can gain new insights from a wide variety of enterprise and public sources, helping companies to build an actionable Big Data strategy.  With OEID’s long-standing differentiation in correlating unstructured information with structured data, business users can now perform their own text mining to identify hidden concepts, without having to request support from IT. They can augment these insights with best in class keyword search and pattern matching, all in the context of rich, interactive visualizations and analytic summaries. · Enterprise-Class Self-Service Discovery:  OEID 3.1 enables IT to provide a powerful self-service platform to the business as part of a broader Business Analytics strategy, preserving the value of existing investments in data quality, governance, and security.  Business users can take advantage of IT-curated information to drive discovery across high volumes and varieties of data, and share insights with colleagues at a moment’s notice. · Harvest Content from the Web with the Endeca Web Acquisition Toolkit:  Oracle now provides best-of-breed data access to website content through the Oracle Endeca Web Acquisition Toolkit.  This provides an agile, graphical interface for developers to rapidly access and integrate any information exposed through a web front-end.  Organizations can now cost-effectively include content from consumer sites, industry forums, government or supplier portals, cloud applications, and myriad other web sources as part of their overall strategy for data discovery and unstructured analytics. For more information: OEID 3.1 OTN Software and Documentation Download And Endeca available for download on Software Delivery Cloud (eDelivery) New OEID 3.1 Videos on YouTube Oracle.com Endeca Site /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin-top:0cm; mso-para-margin-right:0cm; mso-para-margin-bottom:10.0pt; mso-para-margin-left:0cm; line-height:115%; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi; mso-fareast-language:EN-US;}

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• ConcurrentDictionary<TKey,TValue> used with Lazy<T>

  - by Reed

  In a recent thread on the MSDN forum for the TPL, Stephen Toub suggested mixing ConcurrentDictionary<T,U> with Lazy<T>.  This provides a fantastic model for creating a thread safe dictionary of values where the construction of the value type is expensive.  This is an incredibly useful pattern for many operations, such as value caches. The ConcurrentDictionary<TKey, TValue> class was added in .NET 4, and provides a thread-safe, lock free collection of key value pairs.  While this is a fantastic replacement for Dictionary<TKey, TValue>, it has a potential flaw when used with values where construction of the value class is expensive. The typical way this is used is to call a method such as GetOrAdd to fetch or add a value to the dictionary.  It handles all of the thread safety for you, but as a result, if two threads call this simultaneously, two instances of TValue can easily be constructed. If TValue is very expensive to construct, or worse, has side effects if constructed too often, this is less than desirable.  While you can easily work around this with locking, Stephen Toub provided a very clever alternative – using Lazy<TValue> as the value in the dictionary instead. This looks like the following.  Instead of calling: MyValue value = dictionary.GetOrAdd( key, () => new MyValue(key)); .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } We would instead use a ConcurrentDictionary<TKey, Lazy<TValue>>, and write: MyValue value = dictionary.GetOrAdd( key, () => new Lazy<MyValue>( () => new MyValue(key))) .Value; This simple change dramatically changes how the operation works.  Now, if two threads call this simultaneously, instead of constructing two MyValue instances, we construct two Lazy<MyValue> instances. However, the Lazy<T> class is very cheap to construct.  Unlike “MyValue”, we can safely afford to construct this twice and “throw away” one of the instances. We then call Lazy<T>.Value at the end to fetch our “MyValue” instance.  At this point, GetOrAdd will always return the same instance of Lazy<MyValue>.  Since Lazy<T> doesn’t construct the MyValue instance until requested, the actual MyClass instance returned is only constructed once.

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• Bios Memory settings and Virtualization + Ubuntu (Unofficial Answers Welcome) [closed]

  - by TardisGuy

  Attempting to optimize my (Main Windowless) Ubuntu system for my uses I will detail questions below, I understand this might be the wrong place to ask these questions. If so, my apologies and I thank you so much for your patience. Thanks to all the volenteers that have helped me learn ubuntu over the years (Since 5.10) This is a "short" list of questions I have been trying to figure out for some time. If you feel you can answer one but not another, that's already more than I could ask for. I have wrote this up in a format for easy navigation to important points Hopefully to less annoy your eyes. You're welcome :) or i'm sorry i annoy you. :( If you would be so kind, Please format answers as follows: question 1: _ _ _ _ _ or question 1-a: _ _ _ _ _ If you want to simply link me to relevant information, rather than type up something really detailed; that would be more than awesome! Memory Specific Questions Goal: Maximizing memory bandwith to better perform in Virtualization, and Large file compression. (Possible conflict?) Ganged vs Unganged "which is better?"** is relative, i know. But what about ganged vs unganged - With or without Bank/channel interleaving? a: Speculation - If i understand correctly, "channel interleaving has something to do with using both channels to read or write in a kind of "striping" pattern, as opposed to a standard half duplex operation.(probably wrong) but wouldn't ganged channels make this irrelevant? Memory Interleaving(bank). Does it have a down side? Does it require a ratio of clocks? (If I run 4x4gig ddr3) a. If im reading correctly(trying to learn), this is designed to spread operations between latency cycles to work around the higher latency of "normal" operation. b. However it seems to me that it has to be: divisible by fractions of a master clock? So if i run memory at 1333mhz, then the mean between 2 (physical) banks would operate every (roughly) 600Mhz? Warning! Possibly utter nonsense: (1333/2 interleaving to act like 1 memory module per 2 sticks of a total of 4 sticks, meaning 2x channels@4) c. which makes me wonder if there would be left over clock cycles the system would have to... "truncate/balance" or something? But I'm certain theres a feature somewhere i don't understand. Virtualization Questions AMD-V - Option of IOMMU Turned it on, why do i have extra option of "64MB"? If IOMMU is on, but "64MB" is "disabled", Is it on? (have scoured google, I still dont know) a. I think i understand that its supposed to (kind of) "set aside" a part of ram to act as a faster interactive zone for "stuff" (usb, Graphics, and... what?) b. I am using Nvidia graphics on AMD (Used kernel option "iommu=pt iommu=1, pt "passthrough"? No idea what they do, found it on google to solve boot up issue) c. Will this option help me use low latency sound hardware, like my midi keyboard? Can you recommend any additional tweaks? a. sysctl settings? b. swap settings? Grats, youve reached the end. Thanks for Reading.

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• How do you deal with poor management [closed]

  - by Sybiam

  I come from a company where during a project, we saw the client 3 time during the whole project. We were never informed when did the client came in office in order to discuss with him about his requirements. I did setup redmine and told them that if they have any request they can post an issue there. But they never really used redmine to publish anything. They would instead: harass a team member on the phone at any time of the day or night hand us over sheets of paper with new requests or changes hand us over new design (graphical) They requested how much time it would take us to finish the project, I gave them a date and a week to test everything and deployment. I calculated that time taking into account the current features we had to do. And then blamed us that our deadline was wrong and that we lied. But the truth is that one week before that deadline they added a couple of monster feature from nowhere and that week were we were supposed to test and deploy, my friends spent all day in the office changing all little things. After that project, my friend got some kind of depression and got scared everytime his phone rang. They kind of used him as a communication proxy. After that project of hell, (every body got pissed off on that project) as far as I know the designer who was working with us left work after that project and she had some kind of issue too with managers. My team also started looking for work somewhere else. At first I tried to get things straight with management, I tried to make a meeting to discuss about the communication issues and so on.. What really pissed me off and made me leave that job for good is the following. Me: "We have to discuss about what went wrong on the last project. It's quite important" Him: "Lets talk about it in a week or two. Just make a list of all the things you did wrong" Me: "We already have a new project and we want to prevent what happened on the last project to happen again" Him: "Just do it and well have our meeting in a week, make a list of all the thing you did wrong." It kind of ended there then he organized a meeting at a moment I wasn't unable to come. My friend discussed with him and tried to explained him that we really had to discuss about organization issue on how to manage a project. And his answer was pretty much: "During the meeting I don't want to ear how you want to us to manage a project but I want to know what you guys did wrong" After that I felt it wasn't even worth it discussing anything since they weren't even ready listening to us. Found a new job and I'm pretty happy with my choice. I'd like to know how you'd handle such situation. Is there anything to do to solve communication problem? After that project my friend got a depression and some other employee had their down too as far as I know. I wonder what else we can do other than leave these place as soon as possible. Feel sad for the people that are still there and get screamed at just because they need money in order to eat and finding an other job like that isn't that easy. note I died a little when our boss asked us to make a list of things we (programmers) did wrong. This is probably the stupidest request I ever got. If everybody thinks they did everything right, it doesn't mean that there is no problems. Individual problem are rarely the big issue. Colleagues help each others and solve theses issues to prevent problems.

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• Asynchrony in C# 5 (Part II)

  - by javarg

  This article is a continuation of the series of asynchronous features included in the new Async CTP preview for next versions of C# and VB. Check out Part I for more information. So, let’s continue with TPL Dataflow: Asynchronous functions TPL Dataflow Task based asynchronous Pattern Part II: TPL Dataflow Definition (by quote of Async CTP doc): “TPL Dataflow (TDF) is a new .NET library for building concurrent applications. It promotes actor/agent-oriented designs through primitives for in-process message passing, dataflow, and pipelining. TDF builds upon the APIs and scheduling infrastructure provided by the Task Parallel Library (TPL) in .NET 4, and integrates with the language support for asynchrony provided by C#, Visual Basic, and F#.” This means: data manipulation processed asynchronously. “TPL Dataflow is focused on providing building blocks for message passing and parallelizing CPU- and I/O-intensive applications”. Data manipulation is another hot area when designing asynchronous and parallel applications: how do you sync data access in a parallel environment? how do you avoid concurrency issues? how do you notify when data is available? how do you control how much data is waiting to be consumed? etc.  Dataflow Blocks TDF provides data and action processing blocks. Imagine having preconfigured data processing pipelines to choose from, depending on the type of behavior you want. The most basic block is the BufferBlock<T>, which provides an storage for some kind of data (instances of <T>). So, let’s review data processing blocks available. Blocks a categorized into three groups: Buffering Blocks Executor Blocks Joining Blocks Think of them as electronic circuitry components :).. 1. BufferBlock<T>: it is a FIFO (First in First Out) queue. You can Post data to it and then Receive it synchronously or asynchronously. It synchronizes data consumption for only one receiver at a time (you can have many receivers but only one will actually process it). 2. BroadcastBlock<T>: same FIFO queue for messages (instances of <T>) but link the receiving event to all consumers (it makes the data available for consumption to N number of consumers). The developer can provide a function to make a copy of the data if necessary. 3. WriteOnceBlock<T>: it stores only one value and once it’s been set, it can never be replaced or overwritten again (immutable after being set). As with BroadcastBlock<T>, all consumers can obtain a copy of the value. 4. ActionBlock<TInput>: this executor block allows us to define an operation to be executed when posting data to the queue. Thus, we must pass in a delegate/lambda when creating the block. Posting data will result in an execution of the delegate for each data in the queue. You could also specify how many parallel executions to allow (degree of parallelism). 5. TransformBlock<TInput, TOutput>: this is an executor block designed to transform each input, that is way it defines an output parameter. It ensures messages are processed and delivered in order. 6. TransformManyBlock<TInput, TOutput>: similar to TransformBlock but produces one or more outputs from each input. 7. BatchBlock<T>: combines N single items into one batch item (it buffers and batches inputs). 8. JoinBlock<T1, T2, …>: it generates tuples from all inputs (it aggregates inputs). Inputs could be of any type you want (T1, T2, etc.). 9. BatchJoinBlock<T1, T2, …>: aggregates tuples of collections. It generates collections for each type of input and then creates a tuple to contain each collection (Tuple<IList<T1>, IList<T2>>). Next time I will show some examples of usage for each TDF block. * Images taken from Microsoft’s Async CTP documentation.

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• PCI Encryption Key Management

  - by Unicorn Bob

  (Full disclosure: I'm already an active participant here and at StackOverflow, but for reasons that should hopefully be obvious, I'm choosing to ask this particular question anonymously). I currently work for a small software shop that produces software that's sold commercially to manage small- to mid-size business in a couple of fairly specialized industries. Because these industries are customer-facing, a large portion of the software is related to storing and managing customer information. In particular, the storage (and securing) of customer credit card information. With that, of course, comes PCI compliance. To make a long story short, I'm left with a couple of questions about why certain things were done the way they were, and I'm unfortunately without much of a resource at the moment. This is a very small shop (I report directly to the owner, as does the only other full-time employee), and the owner doesn't have an answer to these questions, and the previous developer is...err...unavailable. Issue 1: Periodic Re-encryption As of now, the software prompts the user to do a wholesale re-encryption of all of the sensitive information in the database (basically credit card numbers and user passwords) if either of these conditions is true: There are any NON-encrypted pieces of sensitive information in the database (added through a manual database statement instead of through the business object, for example). This should not happen during the ordinary use of the software. The current key has been in use for more than a particular period of time. I believe it's 12 months, but I'm not certain of that. The point here is that the key "expires". This is my first foray into commercial solution development that deals with PCI, so I am unfortunately uneducated on the practices involved. Is there some aspect of PCI compliance that mandates (or even just strongly recommends) periodic key updating? This isn't a huge issue for me other than I don't currently have a good explanation to give to end users if they ask why they are being prompted to run it. Question 1: Is the concept of key expiration standard, and, if so, is that simply industry-standard or an element of PCI? Issue 2: Key Storage Here's my real issue...the encryption key is stored in the database, just obfuscated. The key is padded on the left and right with a few garbage bytes and some bits are twiddled, but fundamentally there's nothing stopping an enterprising person from examining our (dotfuscated) code, determining the pattern used to turn the stored key into the real key, then using that key to run amok. This seems like a horrible practice to me, but I want to make sure that this isn't just one of those "grin and bear it" practices that people in this industry have taken to. I have developed an alternative approach that would prevent such an attack, but I'm just looking for a sanity check here. Question 2: Is this method of key storage--namely storing the key in the database using an obfuscation method that exists in client code--normal or crazy? Believe me, I know that free advice is worth every penny that I've paid for it, nobody here is an attorney (or at least isn't offering legal advice), caveat emptor, etc. etc., but I'm looking for any input that you all can provide. Thank you in advance!

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• Hopping/Tumbling Windows Could Introduce Latency.

  This is a pre-article to one I am going to be writing on adjusting an event’s time and duration to satisfy business process requirements but it is one that I think is really useful when understanding the way that Hopping/Tumbling windows work within StreamInsight.  A Tumbling window is just a special shortcut version of  a Hopping window where the width of the window is equal to the size of the hop Here is the simplest and often used definition for a Hopping Window.  You can find them all here public static CepWindowStream<CepWindow<TPayload>> HoppingWindow<TPayload>(     this CepStream<TPayload> source,     TimeSpan windowSize,     TimeSpan hopSize,     WindowInputPolicy inputPolicy,     HoppingWindowOutputPolicy outputPolicy )   And here is the definition for a Tumbling Window public static CepWindowStream<CepWindow<TPayload>> TumblingWindow<TPayload>(     this CepStream<TPayload> source,     TimeSpan windowSize,     WindowInputPolicy inputPolicy,     HoppingWindowOutputPolicy outputPolicy )   These methods allow you to group events into windows of a temporal size.  It is a really useful and simple feature in StreamInsight.  One of the downsides though is that the windows cannot be flushed until an event in a following window occurs.  This means that you will potentially never see some events or see them with a delay.  Let me explain. Remember that a stream is a potentially unbounded sequence of events. Events in StreamInsight are given a StartTime.  It is this StartTime that is used to calculate into which temporal window an event falls.  It is best practice to assign a timestamp from the source system and not one from the system clock on the processing server.  StreamInsight cannot know when a window is over.  It cannot tell whether you have received all events in the window or whether some events have been delayed which means that StreamInsight cannot flush the stream for you.   Imagine you have events with the following Timestamps 12:10:10 PM 12:10:20 PM 12:10:35 PM 12:10:45 PM 11:59:59 PM And imagine that you have defined a 1 minute Tumbling Window over this stream using the following syntax var HoppingStream = from shift in inputStream.TumblingWindow(TimeSpan.FromMinutes(1),HoppingWindowOutputPolicy.ClipToWindowEnd) select new WindowCountPayload { CountInWindow = (Int32)shift.Count() };   The events between 12:10:10 PM and 12:10:45 PM will not be seen until the event at 11:59:59 PM arrives.  This could be a real problem if you need to react to windows promptly This can always be worked around by using a different design pattern but a lot of the examples I see assume there is a constant, very frequent stream of events resulting in windows always being flushed. Further examples of using windowing in StreamInsight can be found here

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• How to place rooms proceduraly (rule based) on in a game word

  - by gardian06

  I am trying to design the algorithm for my level generation which is a rule driven system. I have created all the rules for the system. I have taken care to insure that all rooms make sense in a grid type setup. for example: these rooms could make this configuration The logic flow code that I have so far Door{ Vector3 position; POD orient; // 5 possible values (up is not an option) bool Open; } Room{ String roomRule; Vector3 roomPos; Vector3 dimensions; POD roomOrient; // 4 possible values List doors<Door>; } LevelManager{ float scale = 18f; List usedRooms<Room>; List openDoors<Door> bool Grid[][][]; Room CreateRoom(String rule, Vector3 position, POD Orient){ place recieved values based on rule fill in other data } Vector3 getDimenstions(String rule){ return dimensions of the room } RotateRoom(POD rotateAmount){ rotate all items in the room } MoveRoom(Room toBeMoved, POD orientataion, float distance){ move the position of the room based on inputs } GenerateMap(Vector3 size, Vector3 start, Vector3 end){ Grid = array[size.y][size.x][size.z]; Room floatingRoom; floatingRoom = Room.CreateRoom(S01, start, rand(4)); usedRooms.Add(floatingRoom); for each Door in floatingRoom.doors{ openDoors.Add(door); } // fill used grid spaces floatingRoom = Room.CreateRoom(S02, end, rand(4); usedRooms.Add(floatingRoom); for each Door in floatingRoom.doors{ openDoors.Add(door); } Vector3 nRoomLocation; Door workingDoor; string workingRoom; // fill used grid spaces // pick random door on the openDoors list workingDoor = /*randomDoor*/ // get a random rule nRoomLocation = workingDoor.position; // then I'm lost } } I know that I have to make sure for convergence (namely the end is reachable), and to do this until there are no more doors on the openDoors list. right now I am simply trying to get this to work in 2D (there are rules that introduce 3D), but I am working on a presumption that a rigorous algorithm can be trivially extended to 3D. EDIT: my thought pattern so far is to take an existing open door and then pick a random room (restrictions can be put in later) place that room's center at the doors location move the room in the direction of the doors orientation half the rooms dimension w/respect to that axis then test against the 3D array to see if all the grid points are open, or have been used, or if there is even space to put the room (caseEdge) if caseEdge (which can also occur in between rooms) then put the door on a toBeClosed list, and remove it from the open list (placing a wall or something there). then to do some kind of test that both the start, and the goal are connected, and reachable from each other (each room has nodes for AI, but I don't want to "have" to pull those out to accomplish this). but this logic has the problem for say the U, or L shaped rooms in my example, and then I also have a problem conceptually if the room needs to be rotated.

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• Problem in udp socket programing in c

  - by Md. Talha

  I complile the following C code of UDP client after I run './udpclient localhost 9191' in terminal.I put "Enter Text= " as Hello, but it is showing error in sendto as below: Enter text: hello hello : error in sendto()guest-1SDRJ2@md-K42F:~/Desktop$ " Note: I open 1st the server port as below in other terminal ./server 9191. I beleive there is no error in server code. The udp client is not passing message to server. If I don't use thread , the message is passing .But I have to do it by thread. UDP client Code: /* simple UDP echo client */ #include <sys/types.h> #include <sys/socket.h> #include <netinet/in.h> #include <arpa/inet.h> #include <netdb.h> #include <stdio.h> #include <pthread.h> #define STRLEN 1024 static void *readdata(void *); static void *writedata(void *); int sockfd, n, slen; struct sockaddr_in servaddr; char sendline[STRLEN], recvline[STRLEN]; int main(int argc, char *argv[]) { pthread_t readid,writeid; struct sockaddr_in servaddr; struct hostent *h; if(argc != 3) { printf("Usage: %s <proxy server ip> <port>\n", argv[0]); exit(0); } /* create hostent structure from user entered host name*/ if ( (h = gethostbyname(argv[1])) == NULL) { printf("\n%s: error in gethostbyname()", argv[0]); exit(0); } /* create server address structure */ bzero(&servaddr, sizeof(servaddr)); /* initialize it */ servaddr.sin_family = AF_INET; memcpy((char *) &servaddr.sin_addr.s_addr, h->h_addr_list[0], h->h_length); servaddr.sin_port = htons(atoi(argv[2])); /* get the port number from argv[2]*/ /* create a UDP socket: SOCK_DGRAM */ if ( (sockfd = socket(AF_INET,SOCK_DGRAM, 0)) < 0) { printf("\n%s: error in socket()", argv[0]); exit(0); } pthread_create(&readid,NULL,&readdata,NULL); pthread_create(&writeid,NULL,&writedata,NULL); while(1) { }; close(sockfd); } static void * writedata(void *arg) { /* get user input */ printf("\nEnter text: "); do { if (fgets(sendline, STRLEN, stdin) == NULL) { printf("\n%s: error in fgets()"); exit(0); } /* send a text */ if (sendto(sockfd, sendline, sizeof(sendline), 0, (struct sockaddr *) &servaddr, sizeof(servaddr)) < 0) { printf("\n%s: error in sendto()"); exit(0); } }while(1); } static void * readdata(void *arg) { /* wait for echo */ slen = sizeof(servaddr); if ( (n = recvfrom(sockfd, recvline, STRLEN, 0, (struct sockaddr *) &servaddr, &slen)) < 0) { printf("\n%s: error in recvfrom()"); exit(0); } /* null terminate the string */ recvline[n] = 0; fputs(recvline, stdout); }

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• Webcast On-Demand: Building Java EE Apps That Scale

  - by jeckels

  With some awesome work by one of our architects, Randy Stafford, we recently completed a webcast on scaling Java EE apps efficiently. Did you miss it? No problem. We have a replay available on-demand for you. Just hit the '+' sign drop-down for access.Topics include: Domain object caching Service response caching Session state caching JSR-107 HotCache and more! Further, we had several interesting questions asked by our audience, and we thought we'd share a sampling of those here for you - just in case you had the same queries yourself. Enjoy! What is the largest Coherence deployment out there? We have seen deployments with over 500 JVMs in the Coherence cluster, and deployments with over 1000 JVMs using the Coherence jar file, in one system. On the management side there is an ecosystem of monitoring tools from Oracle and third parties with dashboards graphing values from Coherence's JMX instrumentation. For lifecycle management we have seen a lot of custom scripting over the years, but we've also integrated closely with WebLogic to leverage its management ecosystem for deploying Coherence-based applications and managing process life cycles. That integration introduces a new Java EE archive type, the Grid Archive or GAR, which embeds in an EAR and can be seen by a WAR in WebLogic. That integration also doesn't require any extra WebLogic licensing if Coherence is licensed. How is Coherence different from a NoSQL Database like MongoDB? Coherence can be considered a NoSQL technology. It pre-dates the NoSQL movement, having been first released in 2001 whereas the term "NoSQL" was coined in 2009. Coherence has a key-value data model primarily but can also be used for document data models. Coherence manages data in memory currently, though disk persistence is in a future release currently in beta testing. Where the data is managed yields a few differences from the most well-known NoSQL products: access latency is faster with Coherence, though well-known NoSQL databases can manage more data. Coherence also has features that well-known NoSQL database lack, such as grid computing, eventing, and data source integration. Finally Coherence has had 15 years of maturation and hardening from usage in mission-critical systems across a variety of industries, particularly financial services. Can I use Coherence for local caching? Yes, you get additional features beyond just a java.util.Map: you get expiration capabilities, size-limitation capabilities, eventing capabilites, etc. Are there APIs available for GoldenGate HotCache? It's mostly a black box. You configure it, and it just puts objects into your caches. However you can treat it as a glass box, and use Coherence event interceptors to enhance its behavior - and there are use cases for that. Are Coherence caches updated transactionally? Coherence provides several mechanisms for concurrency control. If a project insists on full-blown JTA / XA distributed transactions, Coherence caches can participate as resources. But nobody does that because it's a performance and scalability anti-pattern. At finer granularity, Coherence guarantees strict ordering of all operations (reads and writes) against a single cache key if the operations are done using Coherence's "EntryProcessor" feature. And Coherence has a unique feature called "partition-level transactions" which guarantees atomic writes of multiple cache entries (even in different caches) without requiring JTA / XA distributed transaction semantics.

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• Is there any kind of established architecture for browser based games?

  - by black_puppydog

  I am beginning the development of a broser based game in which players take certain actions at any point in time. Big parts of gameplay will be happening in real life and just have to be entered into the system. I believe a good kind of comparison might be a platform for managing fantasy football, although I have virtually no experience playing that, so please correct me if I am mistaken here. The point is that some events happen in the program (i.e. on the server, out of reach for the players) like pulling new results from some datasource, starting of a new round by a game master and such. Other events happen in real life (two players closing a deal on the transfer of some team member or whatnot - again: have never played fantasy football) and have to be entered into the system. The first part is pretty easy since the game masters will be "staff" and thus can be trusted to a certain degree to not mess with the system. But the second part bothers me quite a lot, especially since the actions may involve multiple steps and interactions with different players, like registering a deal with the system that then has to be approved by the other party or denied and passed on to a game master to decide. I would of course like to separate the game logic as far as possible from the presentation and basic form validation but am unsure how to do this in a clean fashion. Of course I could (and will) put some effort into making my own architectural decisions and prototype different ideas. But I am bound to make some stupid mistakes at some point, so I would like to avoid some of that by getting a little "book smart" beforehand. So the question is: Is there any kind of architectural works that I can read up on? Papers, blogs, maybe design documents or even source code? Writing this down this seems more like a business application with business rules, workflows and such... Any good entry points for that? EDIT: After reading the first answers I am under the impression of having made a mistake when including the "MMO" part into the title. The game will not be all fancy (i.e. 3D or such) on the client side and the logic will completely exist on the server. That is, apart from basic form validation for the user which will also be mirrored on the server side. So the target toolset will be HTML5, JavaScript, probably JQuery(UI). My question is more related to the software architecture/design of a system that enforces certain rules. Separation of ruleset and presentation One problem I am having is that I want to separate the game rules from the presentation. The first step would be to make an own module for the game "engine" that only exposes an interface that allows all actions to be taken in a clean way. If an action fails with regard to some pre/post condition, the engine throws an exception which is then presented to the user like "you cannot sell something you do not own" or "after that you would end up in a situation which is not a valid game state." The problem here is that I would like to be able to not even present invalid action in the first place or grey out the corresponding UI elements. Changing and tweaking the ruleset Another big thing is the ruleset. It will probably evolve over time and most definitely must be tweaked. What's more, it should be possible (to a certain extent) to build a ruleset that fits a specific game round, i.e. choosing different kinds of behaviours in different aspects of the game. This would do something like "we play it with extension A today but we throw out extension B." For me, this screams "Architectural/Design pattern" but I have no idea on who might have published on something like this, not even what to google for.

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