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• The Minimalist Approach to Content Governance - Retire Phase

  - by Kellsey Ruppel

   Originally posted by John Brunswick. Good news - the Retire Phase is actually more fun than the Manage Phase. During the Retire Phase our content management team should not have to track down content creators if the Request Phase of this process was completed successfully. The ownership meta data, success criteria and time stamp that was applied to the original content submission will help to manage content at the end of the content life cycle. The Retire Phase will provide the opportunity for us to prune irrelevant content items through archiving or deletion, keeping the content system clear of irrelevant information, streamlining users ability to browse and search for content.   1. Act on Metrics Established during the Request Phase Why - Some information is only relevant for a given amount of time. In Content Platform Migration Strategy - Artifacts vs Perishable Content we examined two content types - Artifacts and Perishable content. Understanding the differences between Artifacts and Perishable content will allow us to explicitly respect their various lifespans. Additionally, some content may have been part of a project that failed to meet the success criteria outlined in the Request Phase. Any content that did not meet the metrics outlined in the Request Phase should be considered for deletion. How - Thankfully by adhering to to The Minimalist Approach to Content Governance our content should have some level of meta data associated with it that will allow us to quickly sort and understand how to deal with it. Content Management Systems like Oracle's Universal Content Management (UCM) natively allow you to create and save advanced searches that can use content meta data like folders, author, expiration date, security settings and custom meta data to pull back listings of content for examination. Additionally, analytics are available for all content items that allow us to determine if the usage is meeting success criteria that may have been previously outlined during the request phase. The lists that are produced from these approaches can be quickly reviewed for each project with the content owners and based on the nature of the content and success criteria undergo archiving or deletion. Impact - Retiring content that is no longer relevant will allow end users to have fast and relevant access to information across your enterprise. As we mentioned in our first post in this series - it is easy to quickly start producing content, but the challenge is ensuring that the environment is easy to navigate and use on the third week and during the third year. The light level of effort that was placed into the Request Phase of this process will set us up to keep content clean and relevant for a long time to come. With an up-to-date content repository users will be able to quickly find access to the information that is critical to their work processes. You might not get a holiday named in your honor managing the content system, but will appreciate their quick access to quality information.

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• Regular Expressions Reference Tables Updated

  - by Jan Goyvaerts

  The regular expressions reference on the Regular-Expressions.info website was completely overhauled with the big update of that site last month. In the past, the reference section consisted of two parts. One part was a summary of the regex features commonly found in Perl-style regex flavors with short descriptions and examples. This part of the reference ignored differences between regex flavors and omitted most features that don’t have wide support. The other part was a regular expression flavor comparison that listed many more regex features along with YES/no indicators for many regex flavors, but without any explanations of the features. When reworking the site, I wanted to make the reference section more detailed, with descriptions and examples of all the syntax supported by the flavors discussed on the site. Doing that resulted in a reference that lists many features that are only supported by a few regex flavors. For such a reference to be usable, it needs to indicate which flavors support each feature. My original design for the new reference table used two rows for each feature. The first row had 4 columns with a label, syntax, description, and example, similar to the old reference tables. The second row had 20 columns indicating which versions of which flavors support these features. While the double-row design allowed all the information to fit within the table without requiring horizontal scrolling, it made it more difficult to quickly scan the tables for the feature you’re looking for. To make the new reference tables easier to read, they now have only a single row for each feature. The first 4 columns are the same as before. The remaining two columns show which versions of two regular expression flavors support the feature. You can use the drop-down lists above the table to choose the flavors the table should indicate. The site uses cookies to allow the flavor choices to persist while you navigate the reference. The result of this latest update is that the new regex tables are now just as easy to read as the ten-year-old tables on the old site were, while still covering all the features big and small of all the flavors discussed on the site.

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• F# &ndash; Immutable List vs a Mutable Collection in Arrays

  - by MarkPearl

  Another day gone by looking into F#. Today I thought I would ramble on about lists and arrays in F#. Coming from a C# background I barely ever use arrays now days in my C# code – why you may ask – because I find lists generally handle most of the business scenario’s that I come across. So it has been an interesting experience with me keep bumping into Array’s & Lists in F# and I wondered why the frequency of coming across arrays was so much more in this language than in C#. Take for instance the code I stumbled across today. let rng = new Random() let shuffle (array : 'a array) = let n = array.Length for x in 1..n do let i = n-x let j = rng.Next(i+1) let tmp = array.[i] array.[i] <- array.[j] array.[j] <- tmp array   Quite simply its purpose is to “shuffle” an array of items. So I thought, why does it have the “a’ array'” explicitly declared? What if I changed it to a list? Well… as I was about to find out there are some subtle differences between array’s & lists in F# that do not exist in C#. Namely, mutability. A list in F# is an ordered, immutable series of elements of the same type, while an array is a fixed-size zero based, mutable collection of consecutive data elements that are all of the same type. For me the keyword is immutable vs mutable collection. That’s why I could not simply swap the ‘a array with ‘a list in my function header because then later on in the code the syntax would not be valid where I “swap” item positions. i.e. array.[i] <- array.[j] would be invalid because if it was a list, it would be immutable and so couldn’t change by its very definition.. So where does that leave me? It’s to early days to say. I don’t know what the balance will be in future code – will I typically always use lists or arrays or even have a balance, but time will tell.

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• SQL Developer: Why Do You Require Semicolons When Executing SQL in the Worksheet?

  - by thatjeffsmith

  There are many database tools out there that support Oracle database. Oracle SQL Developer just happens to be the one that is produced and shipped by the same folks that bring you the database product. Several other 3rd party tools out there allow you to have a collection of SQL statements in their editor and execute them without requiring a statement delimiter (usually a semicolon.) Let’s look at a quick example: select * from scott.emp select * from hr.employees delete from HR_COPY.BEER where HR_COPY.BEER.STATE like '%West Virginia% In some tools, you can simply place your cursor on say the 2nd statement and ask to execute that statement. The tool assumes that the blank line between it and the next statement, a DELETE, serves as a statement delimiter. This is not bad in and of itself. However, it is very important to understand how your tools work. If you were to try the same trick by running the delete statement, it would empty my entire BEER table instead of just trimming out the breweries from my home state. SQL Developer only executes what you ask it to execute You can paste this same code into SQL Developer and run it without problems and without having to add semicolons to your statements. Highlight what you want executed, and hit Ctrl-Enter If you don’t highlight the text, here’s what you’ll see: See the statement at the cursor vs what SQL Developer actually executed? The parser looks for a query and keeps going until the statement is terminated with a semicolon – UNLESS it’s highlighted, then it assumes you only want to execute what is highlighted. In both cases you are being explicit with what is being sent to the database. Again, there’s not necessarily a ‘right’ or ‘wrong’ debate here. What you need to be aware of is the differences and to learn new workflows if you are moving from other database tools to Oracle SQL Developer. I say, when in doubt, back away from the tool, especially if you’re in production. Oh, and to answer the original question… Because we’re trying to emulate SQL*Plus behavior. You end statements in SQL*Plus with delimiters, and the default delimiter is a semicolon.

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• C#/.NET Little Wonders: The ConcurrentDictionary

  - by James Michael Hare

  Once again we consider some of the lesser known classes and keywords of C#.  In this series of posts, we will discuss how the concurrent collections have been developed to help alleviate these multi-threading concerns.  Last week’s post began with a general introduction and discussed the ConcurrentStack<T> and ConcurrentQueue<T>.  Today's post discusses the ConcurrentDictionary<T> (originally I had intended to discuss ConcurrentBag this week as well, but ConcurrentDictionary had enough information to create a very full post on its own!).  Finally next week, we shall close with a discussion of the ConcurrentBag<T> and BlockingCollection<T>. For more of the "Little Wonders" posts, see the index here. Recap As you'll recall from the previous post, the original collections were object-based containers that accomplished synchronization through a Synchronized member.  While these were convenient because you didn't have to worry about writing your own synchronization logic, they were a bit too finely grained and if you needed to perform multiple operations under one lock, the automatic synchronization didn't buy much. With the advent of .NET 2.0, the original collections were succeeded by the generic collections which are fully type-safe, but eschew automatic synchronization.  This cuts both ways in that you have a lot more control as a developer over when and how fine-grained you want to synchronize, but on the other hand if you just want simple synchronization it creates more work. With .NET 4.0, we get the best of both worlds in generic collections.  A new breed of collections was born called the concurrent collections in the System.Collections.Concurrent namespace.  These amazing collections are fine-tuned to have best overall performance for situations requiring concurrent access.  They are not meant to replace the generic collections, but to simply be an alternative to creating your own locking mechanisms. Among those concurrent collections were the ConcurrentStack<T> and ConcurrentQueue<T> which provide classic LIFO and FIFO collections with a concurrent twist.  As we saw, some of the traditional methods that required calls to be made in a certain order (like checking for not IsEmpty before calling Pop()) were replaced in favor of an umbrella operation that combined both under one lock (like TryPop()). Now, let's take a look at the next in our series of concurrent collections!For some excellent information on the performance of the concurrent collections and how they perform compared to a traditional brute-force locking strategy, see this wonderful whitepaper by the Microsoft Parallel Computing Platform team here. ConcurrentDictionary – the fully thread-safe dictionary The ConcurrentDictionary<TKey,TValue> is the thread-safe counterpart to the generic Dictionary<TKey, TValue> collection.  Obviously, both are designed for quick – O(1) – lookups of data based on a key.  If you think of algorithms where you need lightning fast lookups of data and don’t care whether the data is maintained in any particular ordering or not, the unsorted dictionaries are generally the best way to go. Note: as a side note, there are sorted implementations of IDictionary, namely SortedDictionary and SortedList which are stored as an ordered tree and a ordered list respectively.  While these are not as fast as the non-sorted dictionaries – they are O(log2 n) – they are a great combination of both speed and ordering -- and still greatly outperform a linear search. Now, once again keep in mind that if all you need to do is load a collection once and then allow multi-threaded reading you do not need any locking.  Examples of this tend to be situations where you load a lookup or translation table once at program start, then keep it in memory for read-only reference.  In such cases locking is completely non-productive. However, most of the time when we need a concurrent dictionary we are interleaving both reads and updates.  This is where the ConcurrentDictionary really shines!  It achieves its thread-safety with no common lock to improve efficiency.  It actually uses a series of locks to provide concurrent updates, and has lockless reads!  This means that the ConcurrentDictionary gets even more efficient the higher the ratio of reads-to-writes you have. ConcurrentDictionary and Dictionary differences For the most part, the ConcurrentDictionary<TKey,TValue> behaves like it’s Dictionary<TKey,TValue> counterpart with a few differences.  Some notable examples of which are: Add() does not exist in the concurrent dictionary. This means you must use TryAdd(), AddOrUpdate(), or GetOrAdd().  It also means that you can’t use a collection initializer with the concurrent dictionary. TryAdd() replaced Add() to attempt atomic, safe adds. Because Add() only succeeds if the item doesn’t already exist, we need an atomic operation to check if the item exists, and if not add it while still under an atomic lock. TryUpdate() was added to attempt atomic, safe updates. If we want to update an item, we must make sure it exists first and that the original value is what we expected it to be.  If all these are true, we can update the item under one atomic step. TryRemove() was added to attempt atomic, safe removes. To safely attempt to remove a value we need to see if the key exists first, this checks for existence and removes under an atomic lock. AddOrUpdate() was added to attempt an thread-safe “upsert”. There are many times where you want to insert into a dictionary if the key doesn’t exist, or update the value if it does.  This allows you to make a thread-safe add-or-update. GetOrAdd() was added to attempt an thread-safe query/insert. Sometimes, you want to query for whether an item exists in the cache, and if it doesn’t insert a starting value for it.  This allows you to get the value if it exists and insert if not. Count, Keys, Values properties take a snapshot of the dictionary. Accessing these properties may interfere with add and update performance and should be used with caution. ToArray() returns a static snapshot of the dictionary. That is, the dictionary is locked, and then copied to an array as a O(n) operation.  GetEnumerator() is thread-safe and efficient, but allows dirty reads. Because reads require no locking, you can safely iterate over the contents of the dictionary.  The only downside is that, depending on timing, you may get dirty reads. Dirty reads during iteration The last point on GetEnumerator() bears some explanation.  Picture a scenario in which you call GetEnumerator() (or iterate using a foreach, etc.) and then, during that iteration the dictionary gets updated.  This may not sound like a big deal, but it can lead to inconsistent results if used incorrectly.  The problem is that items you already iterated over that are updated a split second after don’t show the update, but items that you iterate over that were updated a split second before do show the update.  Thus you may get a combination of items that are “stale” because you iterated before the update, and “fresh” because they were updated after GetEnumerator() but before the iteration reached them. Let’s illustrate with an example, let’s say you load up a concurrent dictionary like this: 1: // load up a dictionary. 2: var dictionary = new ConcurrentDictionary<string, int>(); 3:  4: dictionary["A"] = 1; 5: dictionary["B"] = 2; 6: dictionary["C"] = 3; 7: dictionary["D"] = 4; 8: dictionary["E"] = 5; 9: dictionary["F"] = 6; Then you have one task (using the wonderful TPL!) to iterate using dirty reads: 1: // attempt iteration in a separate thread 2: var iterationTask = new Task(() => 3: { 4: // iterates using a dirty read 5: foreach (var pair in dictionary) 6: { 7: Console.WriteLine(pair.Key + ":" + pair.Value); 8: } 9: }); And one task to attempt updates in a separate thread (probably): 1: // attempt updates in a separate thread 2: var updateTask = new Task(() => 3: { 4: // iterates, and updates the value by one 5: foreach (var pair in dictionary) 6: { 7: dictionary[pair.Key] = pair.Value + 1; 8: } 9: }); Now that we’ve done this, we can fire up both tasks and wait for them to complete: 1: // start both tasks 2: updateTask.Start(); 3: iterationTask.Start(); 4:  5: // wait for both to complete. 6: Task.WaitAll(updateTask, iterationTask); Now, if I you didn’t know about the dirty reads, you may have expected to see the iteration before the updates (such as A:1, B:2, C:3, D:4, E:5, F:6).  However, because the reads are dirty, we will quite possibly get a combination of some updated, some original.  My own run netted this result: 1: F:6 2: E:6 3: D:5 4: C:4 5: B:3 6: A:2 Note that, of course, iteration is not in order because ConcurrentDictionary, like Dictionary, is unordered.  Also note that both E and F show the value 6.  This is because the output task reached F before the update, but the updates for the rest of the items occurred before their output (probably because console output is very slow, comparatively). If we want to always guarantee that we will get a consistent snapshot to iterate over (that is, at the point we ask for it we see precisely what is in the dictionary and no subsequent updates during iteration), we should iterate over a call to ToArray() instead: 1: // attempt iteration in a separate thread 2: var iterationTask = new Task(() => 3: { 4: // iterates using a dirty read 5: foreach (var pair in dictionary.ToArray()) 6: { 7: Console.WriteLine(pair.Key + ":" + pair.Value); 8: } 9: }); The atomic Try…() methods As you can imagine TryAdd() and TryRemove() have few surprises.  Both first check the existence of the item to determine if it can be added or removed based on whether or not the key currently exists in the dictionary: 1: // try add attempts an add and returns false if it already exists 2: if (dictionary.TryAdd("G", 7)) 3: Console.WriteLine("G did not exist, now inserted with 7"); 4: else 5: Console.WriteLine("G already existed, insert failed."); TryRemove() also has the virtue of returning the value portion of the removed entry matching the given key: 1: // attempt to remove the value, if it exists it is removed and the original is returned 2: int removedValue; 3: if (dictionary.TryRemove("C", out removedValue)) 4: Console.WriteLine("Removed C and its value was " + removedValue); 5: else 6: Console.WriteLine("C did not exist, remove failed."); Now TryUpdate() is an interesting creature.  You might think from it’s name that TryUpdate() first checks for an item’s existence, and then updates if the item exists, otherwise it returns false.  Well, note quite... It turns out when you call TryUpdate() on a concurrent dictionary, you pass it not only the new value you want it to have, but also the value you expected it to have before the update.  If the item exists in the dictionary, and it has the value you expected, it will update it to the new value atomically and return true.  If the item is not in the dictionary or does not have the value you expected, it is not modified and false is returned. 1: // attempt to update the value, if it exists and if it has the expected original value 2: if (dictionary.TryUpdate("G", 42, 7)) 3: Console.WriteLine("G existed and was 7, now it's 42."); 4: else 5: Console.WriteLine("G either didn't exist, or wasn't 7."); The composite Add methods The ConcurrentDictionary also has composite add methods that can be used to perform updates and gets, with an add if the item is not existing at the time of the update or get. The first of these, AddOrUpdate(), allows you to add a new item to the dictionary if it doesn’t exist, or update the existing item if it does.  For example, let’s say you are creating a dictionary of counts of stock ticker symbols you’ve subscribed to from a market data feed: 1: public sealed class SubscriptionManager 2: { 3: private readonly ConcurrentDictionary<string, int> _subscriptions = new ConcurrentDictionary<string, int>(); 4:  5: // adds a new subscription, or increments the count of the existing one. 6: public void AddSubscription(string tickerKey) 7: { 8: // add a new subscription with count of 1, or update existing count by 1 if exists 9: var resultCount = _subscriptions.AddOrUpdate(tickerKey, 1, (symbol, count) => count + 1); 10:  11: // now check the result to see if we just incremented the count, or inserted first count 12: if (resultCount == 1) 13: { 14: // subscribe to symbol... 15: } 16: } 17: } Notice the update value factory Func delegate.  If the key does not exist in the dictionary, the add value is used (in this case 1 representing the first subscription for this symbol), but if the key already exists, it passes the key and current value to the update delegate which computes the new value to be stored in the dictionary.  The return result of this operation is the value used (in our case: 1 if added, existing value + 1 if updated). Likewise, the GetOrAdd() allows you to attempt to retrieve a value from the dictionary, and if the value does not currently exist in the dictionary it will insert a value.  This can be handy in cases where perhaps you wish to cache data, and thus you would query the cache to see if the item exists, and if it doesn’t you would put the item into the cache for the first time: 1: public sealed class PriceCache 2: { 3: private readonly ConcurrentDictionary<string, double> _cache = new ConcurrentDictionary<string, double>(); 4:  5: // adds a new subscription, or increments the count of the existing one. 6: public double QueryPrice(string tickerKey) 7: { 8: // check for the price in the cache, if it doesn't exist it will call the delegate to create value. 9: return _cache.GetOrAdd(tickerKey, symbol => GetCurrentPrice(symbol)); 10: } 11:  12: private double GetCurrentPrice(string tickerKey) 13: { 14: // do code to calculate actual true price. 15: } 16: } There are other variations of these two methods which vary whether a value is provided or a factory delegate, but otherwise they work much the same. Oddities with the composite Add methods The AddOrUpdate() and GetOrAdd() methods are totally thread-safe, on this you may rely, but they are not atomic.  It is important to note that the methods that use delegates execute those delegates outside of the lock.  This was done intentionally so that a user delegate (of which the ConcurrentDictionary has no control of course) does not take too long and lock out other threads. This is not necessarily an issue, per se, but it is something you must consider in your design.  The main thing to consider is that your delegate may get called to generate an item, but that item may not be the one returned!  Consider this scenario: A calls GetOrAdd and sees that the key does not currently exist, so it calls the delegate.  Now thread B also calls GetOrAdd and also sees that the key does not currently exist, and for whatever reason in this race condition it’s delegate completes first and it adds its new value to the dictionary.  Now A is done and goes to get the lock, and now sees that the item now exists.  In this case even though it called the delegate to create the item, it will pitch it because an item arrived between the time it attempted to create one and it attempted to add it. Let’s illustrate, assume this totally contrived example program which has a dictionary of char to int.  And in this dictionary we want to store a char and it’s ordinal (that is, A = 1, B = 2, etc).  So for our value generator, we will simply increment the previous value in a thread-safe way (perhaps using Interlocked): 1: public static class Program 2: { 3: private static int _nextNumber = 0; 4:  5: // the holder of the char to ordinal 6: private static ConcurrentDictionary<char, int> _dictionary 7: = new ConcurrentDictionary<char, int>(); 8:  9: // get the next id value 10: public static int NextId 11: { 12: get { return Interlocked.Increment(ref _nextNumber); } 13: } Then, we add a method that will perform our insert: 1: public static void Inserter() 2: { 3: for (int i = 0; i < 26; i++) 4: { 5: _dictionary.GetOrAdd((char)('A' + i), key => NextId); 6: } 7: } Finally, we run our test by starting two tasks to do this work and get the results… 1: public static void Main() 2: { 3: // 3 tasks attempting to get/insert 4: var tasks = new List<Task> 5: { 6: new Task(Inserter), 7: new Task(Inserter) 8: }; 9:  10: tasks.ForEach(t => t.Start()); 11: Task.WaitAll(tasks.ToArray()); 12:  13: foreach (var pair in _dictionary.OrderBy(p => p.Key)) 14: { 15: Console.WriteLine(pair.Key + ":" + pair.Value); 16: } 17: } If you run this with only one task, you get the expected A:1, B:2, ..., Z:26.  But running this in parallel you will get something a bit more complex.  My run netted these results: 1: A:1 2: B:3 3: C:4 4: D:5 5: E:6 6: F:7 7: G:8 8: H:9 9: I:10 10: J:11 11: K:12 12: L:13 13: M:14 14: N:15 15: O:16 16: P:17 17: Q:18 18: R:19 19: S:20 20: T:21 21: U:22 22: V:23 23: W:24 24: X:25 25: Y:26 26: Z:27 Notice that B is 3?  This is most likely because both threads attempted to call GetOrAdd() at roughly the same time and both saw that B did not exist, thus they both called the generator and one thread got back 2 and the other got back 3.  However, only one of those threads can get the lock at a time for the actual insert, and thus the one that generated the 3 won and the 3 was inserted and the 2 got discarded.  This is why on these methods your factory delegates should be careful not to have any logic that would be unsafe if the value they generate will be pitched in favor of another item generated at roughly the same time.  As such, it is probably a good idea to keep those generators as stateless as possible. Summary The ConcurrentDictionary is a very efficient and thread-safe version of the Dictionary generic collection.  It has all the benefits of type-safety that it’s generic collection counterpart does, and in addition is extremely efficient especially when there are more reads than writes concurrently. Tweet Technorati Tags: C#, .NET, Concurrent Collections, Collections, Little Wonders, Black Rabbit Coder,James Michael Hare

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• SQL SERVER – Difference Between CURRENT_TIMESTAMP and GETDATE() – CURRENT_TIMESTAMP Equivalent in SQL Server

  - by pinaldave

  A common question – I often get from Oracle/MySQL Professionals: “What is the Equivalent to CURRENT_TIMESTAMP in SQL Server?” Here is a common question I often get from SQL Server Professionals: “What are differences between Difference Between CURRENT_TIMESTAMP and GETDATE ()?” Very simple question but have showed up so frequently that I feel like to write about it. Well in SQL Server GETDATE() is Equivalent to CURRENT_TIMESTAMP. However, if you use CURRENT_TIMESTAMP in your select statement it will work fine. You can see in the above example – both of them returns the same value. Now let us go to next question regarding difference between GETDATE and CURRENT_TIMESTAMP. Well, the matter of the fact, there is no difference between them in SQL Server (Reference Link). CURRENT_TIMESTAMP is an ANSI SQL function, whereas GETDATE is T-SQL implementation of the same function. Both of them derive value from the operating system of the computer on which SQL Server instance is running. Above discussion prompts another question – in this case, what should one use GETDATE or CURRENT_TIMESTAMP? Well, this is indeed tricky and interesting question. I think I am very comfortable using the GETDATE () so I will go to use it but a matter of the fact there is no right or wrong answer. If you want to follow ancient saying “When in Rome, do as the Romans do”, I suggest using the GETDATE (), or continue using CURRENT_TIMESTAMP. With that said, there is one very important property we all need to keep in mind. If you use CURRENT_TIMESTAMP while creating an object, they are automatically converted to GETDATE() and stored internally. To illustrate what I am suggesting here is the example - Create a table using the following script CREATE TABLE [dbo].[TestTable]( [Cold2] [datetime] NULL ) ON [PRIMARY] GO ALTER TABLE [dbo].[TestTable] ADD DEFAULT (CURRENT_TIMESTAMP) FOR [Cold2] GO Now go to SSMS and generate the script for the table and you will notice following syntax. CREATE TABLE [dbo].[TestTable]( [Cold2] [datetime] NULL ) ON [PRIMARY] GO ALTER TABLE [dbo].[TestTable] ADD DEFAULT (GETDATE()) FOR [Cold2] GO You can notice that SQL Server have automatically converted CURRENT_TIMESTAMP to GETDATE(). I guess this gives us an idea how they behave. Now go ahead and make your choice! Do let me know which one will you use CURRENT_TIMESTAMP or GETDATE () in the comments area. Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: PostADay, SQL, SQL Authority, SQL DateTime, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology

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• Towards Database Continuous Delivery – What Next after Continuous Integration? A Checklist

  - by Ben Rees

  .dbd-banner p{ font-size:0.75em; padding:0 0 10px; margin:0 } .dbd-banner p span{ color:#675C6D; } .dbd-banner p:last-child{ padding:0; } @media ALL and (max-width:640px){ .dbd-banner{ background:#f0f0f0; padding:5px; color:#333; margin-top: 5px; } } -- Database delivery patterns & practices STAGE 4 AUTOMATED DEPLOYMENT If you’ve been fortunate enough to get to the stage where you’ve implemented some sort of continuous integration process for your database updates, then hopefully you’re seeing the benefits of that investment – constant feedback on changes your devs are making, advanced warning of data loss (prior to the production release on Saturday night!), a nice suite of automated tests to check business logic, so you know it’s going to work when it goes live, and so on. But what next? What can you do to improve your delivery process further, moving towards a full continuous delivery process for your database? In this article I describe some of the issues you might need to tackle on the next stage of this journey, and how to plan to overcome those obstacles before they appear. Our Database Delivery Learning Program consists of four stages, really three – source controlling a database, running continuous integration processes, then how to set up automated deployment (the middle stage is split in two – basic and advanced continuous integration, making four stages in total). If you’ve managed to work through the first three of these stages – source control, basic, then advanced CI, then you should have a solid change management process set up where, every time one of your team checks in a change to your database (whether schema or static reference data), this change gets fully tested automatically by your CI server. But this is only part of the story. Great, we know that our updates work, that the upgrade process works, that the upgrade isn’t going to wipe our 4Tb of production data with a single DROP TABLE. But – how do you get this (fully tested) release live? Continuous delivery means being always ready to release your software at any point in time. There’s a significant gap between your latest version being tested, and it being easily releasable. Just a quick note on terminology – there’s a nice piece here from Atlassian on the difference between continuous integration, continuous delivery and continuous deployment. This piece also gives a nice description of the benefits of continuous delivery. These benefits have been summed up by Jez Humble at Thoughtworks as: “Continuous delivery is a set of principles and practices to reduce the cost, time, and risk of delivering incremental changes to users” There’s another really useful piece here on Simple-Talk about the need for continuous delivery and how it applies to the database written by Phil Factor – specifically the extra needs and complexities of implementing a full CD solution for the database (compared to just implementing CD for, say, a web app). So, hopefully you’re convinced of moving on the the next stage! The next step after CI is to get some sort of automated deployment (or “release management”) process set up. But what should I do next? What do I need to plan and think about for getting my automated database deployment process set up? Can’t I just install one of the many release management tools available and hey presto, I’m ready! If only it were that simple. Below I list some of the areas that it’s worth spending a little time on, where a little planning and prep could go a long way. It’s also worth pointing out, that this should really be an evolving process. Depending on your starting point of course, it can be a long journey from your current setup to a full continuous delivery pipeline. If you’ve got a CI mechanism in place, you’re certainly a long way down that path. Nevertheless, we’d recommend evolving your process incrementally. Pages 157 and 129-141 of the book on Continuous Delivery (by Jez Humble and Dave Farley) have some great guidance on building up a pipeline incrementally: http://www.amazon.com/Continuous-Delivery-Deployment-Automation-Addison-Wesley/dp/0321601912 For now, in this post, we’ll look at the following areas for your checklist: You and Your Team Environments The Deployment Process Rollback and Recovery Development Practices You and Your Team It’s a cliché in the DevOps community that “It’s not all about processes and tools, really it’s all about a culture”. As stated in this DevOps report from Puppet Labs: “DevOps processes and tooling contribute to high performance, but these practices alone aren’t enough to achieve organizational success. The most common barriers to DevOps adoption are cultural: lack of manager or team buy-in, or the value of DevOps isn’t understood outside of a specific group”. Like most clichés, there’s truth in there – if you want to set up a database continuous delivery process, you need to get your boss, your department, your company (if relevant) onside. Why? Because it’s an investment with the benefits coming way down the line. But the benefits are huge – for HP, in the book A Practical Approach to Large-Scale Agile Development: How HP Transformed LaserJet FutureSmart Firmware, these are summarized as: -2008 to present: overall development costs reduced by 40% -Number of programs under development increased by 140% -Development costs per program down 78% -Firmware resources now driving innovation increased by a factor of 8 (from 5% working on new features to 40% But what does this mean? It means that, when moving to the next stage, to make that extra investment in automating your deployment process, it helps a lot if everyone is convinced that this is a good thing. That they understand the benefits of automated deployment and are willing to make the effort to transform to a new way of working. Incidentally, if you’re ever struggling to convince someone of the value I’d strongly recommend just buying them a copy of this book – a great read, and a very practical guide to how it can really work at a large org. I’ve spoken to many customers who have implemented database CI who describe their deployment process as “The point where automation breaks down. Up to that point, the CI process runs, untouched by human hand, but as soon as that’s finished we revert to manual.” This deployment process can involve, for example, a DBA manually comparing an environment (say, QA) to production, creating the upgrade scripts, reading through them, checking them against an Excel document emailed to him/her the night before, turning to page 29 in his/her notebook to double-check how replication is switched off and on for deployments, and so on and so on. Painful, error-prone and lengthy. But the point is, if this is something like your deployment process, telling your DBA “We’re changing everything you do and your toolset next week, to automate most of your role – that’s okay isn’t it?” isn’t likely to go down well. There’s some work here to bring him/her onside – to explain what you’re doing, why there will still be control of the deployment process and so on. Or of course, if you’re the DBA looking after this process, you have to do a similar job in reverse. You may have researched and worked out how you’d like to change your methodology to start automating your painful release process, but do the dev team know this? What if they have to start producing different artifacts for you? Will they be happy with this? Worth talking to them, to find out. As well as talking to your DBA/dev team, the other group to get involved before implementation is your manager. And possibly your manager’s manager too. As mentioned, unless there’s buy-in “from the top”, you’re going to hit problems when the implementation starts to get rocky (and what tool/process implementations don’t get rocky?!). You need to have support from someone senior in your organisation – someone you can turn to when you need help with a delayed implementation, lack of resources or lack of progress. Actions: Get your DBA involved (or whoever looks after live deployments) and discuss what you’re planning to do or, if you’re the DBA yourself, get the dev team up-to-speed with your plans, Get your boss involved too and make sure he/she is bought in to the investment. Environments Where are you going to deploy to? And really this question is – what environments do you want set up for your deployment pipeline? Assume everyone has “Production”, but do you have a QA environment? Dedicated development environments for each dev? Proper pre-production? I’ve seen every setup under the sun, and there is often a big difference between “What we want, to do continuous delivery properly” and “What we’re currently stuck with”. Some of these differences are: What we want What we’ve got Each developer with their own dedicated database environment A single shared “development” environment, used by everyone at once An Integration box used to test the integration of all check-ins via the CI process, along with a full suite of unit-tests running on that machine In fact if you have a CI process running, you’re likely to have some sort of integration server running (even if you don’t call it that!). Whether you have a full suite of unit tests running is a different question… Separate QA environment used explicitly for manual testing prior to release “We just test on the dev environments, or maybe pre-production” A proper pre-production (or “staging”) box that matches production as closely as possible Hopefully a pre-production box of some sort. But does it match production closely!? A production environment reproducible from source control A production box which has drifted significantly from anything in source control The big question is – how much time and effort are you going to invest in fixing these issues? In reality this just involves figuring out which new databases you’re going to create and where they’ll be hosted – VMs? Cloud-based? What about size/data issues – what data are you going to include on dev environments? Does it need to be masked to protect access to production data? And often the amount of work here really depends on whether you’re working on a new, greenfield project, or trying to update an existing, brownfield application. There’s a world if difference between starting from scratch with 4 or 5 clean environments (reproducible from source control of course!), and trying to re-purpose and tweak a set of existing databases, with all of their surrounding processes and quirks. But for a proper release management process, ideally you have: Dedicated development databases, An Integration server used for testing continuous integration and running unit tests. [NB: This is the point at which deployments are automatic, without human intervention. Each deployment after this point is a one-click (but human) action], QA – QA engineers use a one-click deployment process to automatically* deploy chosen releases to QA for testing, Pre-production. The environment you use to test the production release process, Production. * A note on the use of the word “automatic” – when carrying out automated deployments this does not mean that the deployment is happening without human intervention (i.e. that something is just deploying over and over again). It means that the process of carrying out the deployment is automatic in that it’s not a person manually running through a checklist or set of actions. The deployment still requires a single-click from a user. Actions: Get your environments set up and ready, Set access permissions appropriately, Make sure everyone understands what the environments will be used for (it’s not a “free-for-all” with all environments to be accessed, played with and changed by development). The Deployment Process As described earlier, most existing database deployment processes are pretty manual. The following is a description of a process we hear very often when we ask customers “How do your database changes get live? How does your manual process work?” Check pre-production matches production (use a schema compare tool, like SQL Compare). Sometimes done by taking a backup from production and restoring in to pre-prod, Again, use a schema compare tool to find the differences between the latest version of the database ready to go live (i.e. what the team have been developing). This generates a script, User (generally, the DBA), reviews the script. This often involves manually checking updates against a spreadsheet or similar, Run the script on pre-production, and check there are no errors (i.e. it upgrades pre-production to what you hoped), If all working, run the script on production.* * this assumes there’s no problem with production drifting away from pre-production in the interim time period (i.e. someone has hacked something in to the production box without going through the proper change management process). This difference could undermine the validity of your pre-production deployment test. Red Gate is currently working on a free tool to detect this problem – sign up here at www.sqllighthouse.com, if you’re interested in testing early versions. There are several variations on this process – some better, some much worse! How do you automate this? In particular, step 3 – surely you can’t automate a DBA checking through a script, that everything is in order!? The key point here is to plan what you want in your new deployment process. There are so many options. At one extreme, pure continuous deployment – whenever a dev checks something in to source control, the CI process runs (including extensive and thorough testing!), before the deployment process keys in and automatically deploys that change to the live box. Not for the faint hearted – and really not something we recommend. At the other extreme, you might be more comfortable with a semi-automated process – the pre-production/production matching process is automated (with an error thrown if these environments don’t match), followed by a manual intervention, allowing for script approval by the DBA. One he/she clicks “Okay, I’m happy for that to go live”, the latter stages automatically take the script through to live. And anything in between of course – and other variations. But we’d strongly recommended sitting down with a whiteboard and your team, and spending a couple of hours mapping out “What do we do now?”, “What do we actually want?”, “What will satisfy our needs for continuous delivery, but still maintaining some sort of continuous control over the process?” NB: Most of what we’re discussing here is about production deployments. It’s important to note that you will also need to map out a deployment process for earlier environments (for example QA). However, these are likely to be less onerous, and many customers opt for a much more automated process for these boxes. Actions: Sit down with your team and a whiteboard, and draw out the answers to the questions above for your production deployments – “What do we do now?”, “What do we actually want?”, “What will satisfy our needs for continuous delivery, but still maintaining some sort of continuous control over the process?” Repeat for earlier environments (QA and so on). Rollback and Recovery If only every deployment went according to plan! Unfortunately they don’t – and when things go wrong, you need a rollback or recovery plan for what you’re going to do in that situation. Once you move in to a more automated database deployment process, you’re far more likely to be deploying more frequently than before. No longer once every 6 months, maybe now once per week, or even daily. Hence the need for a quick rollback or recovery process becomes paramount, and should be planned for. NB: These are mainly scenarios for handling rollbacks after the transaction has been committed. If a failure is detected during the transaction, the whole transaction can just be rolled back, no problem. There are various options, which we’ll explore in subsequent articles, things like: Immediately restore from backup, Have a pre-tested rollback script (remembering that really this is a “roll-forward” script – there’s not really such a thing as a rollback script for a database!) Have fallback environments – for example, using a blue-green deployment pattern. Different options have pros and cons – some are easier to set up, some require more investment in infrastructure; and of course some work better than others (the key issue with using backups, is loss of the interim transaction data that has been added between the failed deployment and the restore). The best mechanism will be primarily dependent on how your application works and how much you need a cast-iron failsafe mechanism. Actions: Work out an appropriate rollback strategy based on how your application and business works, your appetite for investment and requirements for a completely failsafe process. Development Practices This is perhaps the more difficult area for people to tackle. The process by which you can deploy database updates is actually intrinsically linked with the patterns and practices used to develop that database and linked application. So you need to decide whether you want to implement some changes to the way your developers actually develop the database (particularly schema changes) to make the deployment process easier. A good example is the pattern “Branch by abstraction”. Explained nicely here, by Martin Fowler, this is a process that can be used to make significant database changes (e.g. splitting a table) in a step-wise manner so that you can always roll back, without data loss – by making incremental updates to the database backward compatible. Slides 103-108 of the following slidedeck, from Niek Bartholomeus explain the process: https://speakerdeck.com/niekbartho/orchestration-in-meatspace As these slides show, by making a significant schema change in multiple steps – where each step can be rolled back without any loss of new data – this affords the release team the opportunity to have zero-downtime deployments with considerably less stress (because if an increment goes wrong, they can roll back easily). There are plenty more great patterns that can be implemented – the book Refactoring Databases, by Scott Ambler and Pramod Sadalage is a great read, if this is a direction you want to go in: http://www.amazon.com/Refactoring-Databases-Evolutionary-paperback-Addison-Wesley/dp/0321774515 But the question is – how much of this investment are you willing to make? How often are you making significant schema changes that would require these best practices? Again, there’s a difference here between migrating old projects and starting afresh – with the latter it’s much easier to instigate best practice from the start. Actions: For your business, work out how far down the path you want to go, amending your database development patterns to “best practice”. It’s a trade-off between implementing quality processes, and the necessity to do so (depending on how often you make complex changes). Socialise these changes with your development group. No-one likes having “best practice” changes imposed on them, so good to introduce these ideas and the rationale behind them early.   Summary The next stages of implementing a continuous delivery pipeline for your database changes (once you have CI up and running) require a little pre-planning, if you want to get the most out of the work, and for the implementation to go smoothly. We’ve covered some of the checklist of areas to consider – mainly in the areas of “Getting the team ready for the changes that are coming” and “Planning our your pipeline, environments, patterns and practices for development”, though there will be more detail, depending on where you’re coming from – and where you want to get to. This article is part of our database delivery patterns & practices series on Simple Talk. Find more articles for version control, automated testing, continuous integration & deployment.

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• Why All The Hype Around Live Help?

  - by ruth.donohue

  I am pleased to introduce guest blogger, Damien Acheson today. Based in Cambridge, MA, Damien is the Product Marketing Manager for ATG’s Live Help products. Welcome, Damien!! BY DAMIEN ACHESON Why all the hype around live help? An eCommerce professional recently asked me: “Why all the hype around live chat and click to call?” I already have a customer service phone number that’s available to my online visitors. Why would I want to add live help? If anything, I want my website to reduce the number of calls to my contact center, not increase it!” The effect of adding live help to a website is counter-intuitive. Done right, live help doesn’t increase your call volume; it optimizes it by replacing traditional telephone calls with smarter, more productive, live voice and live chat interactions. This generates instant cost savings, and a measurable lift in sales and customer retention. A live help interaction differs from a traditional telephone call in six radical ways: Targeting. With live help you can target specific visitors at just the exact right time with a live call or live chat invitation based on hundreds of different parameters. For example, visitors who appear to hesitate before making a large purchase may receive a live help invitation, while others may not. Productivity. By reserving live voice to visitors with complex questions, and offering self-service and live chat for more simple interactions, agents with the right domain expertise can handle simultaneous queries and achieve substantial productivity gains. Routing. Live help interactions take into account visitors’ web context to intelligently route queries to the best available agent, thereby lifting first contact resolution. Context. Traditional telephone numbers force online customers to “change channels” and “start over” with a phone agent. With Live help, agents get the context of the web session and can instantly access the customer’s transaction details and account information, substantially reducing handle times. Interaction. Agents can solve a customer’s problem more effectively co-browsing and collaborating with the visitor in real-time to complete online forms and transactions. Analytics. Unlike traditional telephone numbers, live help allows you to tie Web analytics to customer satisfaction and agent performance indicators. To better understand these differences and advantages over traditional customer service, watch this demo on optimizing customer interactions with Live Help. Technorati Tags: ATG,Live Help,Commerce

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• Izenda Reports 6.3 Top 10 Features

  - by gt0084e1

  Izenda 6.3 Top 10 New Features and Capabilities 1. Izenda Maps Add-On The Izenda Maps add-on allows rapid visualization of geographic or geo-spacial data.  It is fully integrated with the the rest of Izenda report package and adds a Maps tab which allows users to add interactive maps to their reports. Contact your representative or [email protected] for limited time discounts. Izenda Maps even has rich drill-down capabilities that allow you to dive deeper with a simple hover (also requires dashboards). 2. Streamlined Pie Charts with "Other" Slices The advanced properties of the Pie Chart now allows you to combine the smaller slices into a single "Other" slice. This reduces the visual complexity without throwing off the scale of the chart. Compare the difference below. 3. Combined Bar + Line Charts The Bar chart now allows dual visualization of multiple metrics simultaneously by adding a line for secondary data. Enabled via AdHocSettings.AllowLineOnBar = true; 4. Stacked Bar Charts The stacked bar chart lets you see a breakdown of a measure based on categorical data.  It is enabled with the following code. AdHocSettings.AllowStackedBarChart = true; 5. Self-Joining Data Sources The self-join features allows for parent-child relationships to be accessed from the Data Sources tab. The same table can be used as a secondary child table within the Report Designer. 6. Report Design From Dashboard View Dashboards now sport both view and design icons to allow quick access to both. 7. Field Arithmetic on Dates Differences between dates can now be used as measures with the arithmetic feature. 8. Simplified Multi-Tenancy Integrating with multi-tenant systems is now easier than ever. The following APIs have been added to facilitate common scenarios. AdHocSettings.CurrentUserTenantId = value; AdHocSettings.SchedulerTenantID = value; AdHocSettings.SchedulerTenantField = "AccountID"; 9. Support For SQL 2008 R2 and SQL Azure Izenda now supports the latest version of Microsoft's database as well as the SQL Azure service. 10. Enhanced Performance and Compatibility for Stored Procedures Izenda now supports more stored procedures than ever and runs them faster too.

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• How to Quickly Add Multiple IP Addresses to Windows Servers

  - by Sysadmin Geek

  If you have ever added multiple IP addresses to a single Windows server, going through the graphical interface is an incredible pain as each IP must be added manually, each in a new dialog box. Here’s a simple solution. Needless to say, this can be incredibly monotonous and time consuming if you are adding more than a few IP addresses. Thankfully, there is a much easier way which allows you to add an entire subnet (or more) in seconds. Adding an IP Address from the Command Line Windows includes the “netsh” command which allows you to configure just about any aspect of your network connections. If you view the accepted parameters using “netsh /?” you will be presented with a list of commands each which have their own list of commands (and so on). For the purpose of adding IP addresses, we are interested in this string of parameters: netsh interface ipv4 add address Note: For Windows Server 2003/XP and earlier, “ipv4″ should be replaced with just “ip” in the netsh command. If you view the help information, you can see the full list of accepted parameters but for the most part what you will be interested in is something like this: netsh interface ipv4 add address “Local Area Connection” 192.168.1.2 255.255.255.0 The above command adds the IP Address 192.168.1.2 (with Subnet Mask 255.255.255.0) to the connection titled “Local Area Network”. Adding Multiple IP Addresses at Once When we accompany a netsh command with the FOR /L loop, we can quickly add multiple IP addresses. The syntax for the FOR /L loop looks like this: FOR /L %variable IN (start,step,end) DO command So we could easily add every IP address from an entire subnet using this command: FOR /L %A IN (0,1,255) DO netsh interface ipv4 add address “Local Area Connection” 192.168.1.%A 255.255.255.0 This command takes about 20 seconds to run, where adding the same number of IP addresses manually would take significantly longer. A Quick Demonstration Here is the initial configuration on our network adapter: ipconfig /all Now run netsh from within a FOR /L loop to add IP’s 192.168.1.10-20 to this adapter: FOR /L %A IN (10,1,20) DO netsh interface ipv4 add address “Local Area Connection” 192.168.1.%A 255.255.255.0 After the above command is run, viewing the IP Configuration of the adapter now shows: Latest Features How-To Geek ETC How To Create Your Own Custom ASCII Art from Any Image How To Process Camera Raw Without Paying for Adobe Photoshop How Do You Block Annoying Text Message (SMS) Spam? How to Use and Master the Notoriously Difficult Pen Tool in Photoshop HTG Explains: What Are the Differences Between All Those Audio Formats? How To Use Layer Masks and Vector Masks to Remove Complex Backgrounds in Photoshop Bring Summer Back to Your Desktop with the LandscapeTheme for Chrome and Iron The Prospector – Home Dash Extension Creates a Whole New Browsing Experience in Firefox KinEmote Links Kinect to Windows Why Nobody Reads Web Site Privacy Policies [Infographic] Asian Temple in the Snow Wallpaper 10 Weird Gaming Records from the Guinness Book

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• Excel Solver vs Solver Foundation

  - by JoshReuben

  I recently read a book http://www.amazon.com/Scientific-Engineering-Cookbook-Cookbooks-OReilly/dp/0596008791/ref=sr_1_1?ie=UTF8&s=books&qid=1296593374&sr=8-1 - the Excel Scientific and Engineering Cookbook.     The 2 main tools that this book leveraged were the Data Analysis Pack and Excel Solver. I had previously been aquanted with Microsoft Solver Foundation - this is a full fledged API for solving optimization problems, and went beyond being a mere Excel plugin - it exposed a C# programmatic interface for in process and a web service interface for out of process integration. were they the same? apparently not!   2 different solver frameworks for Excel: http://www.solver.com/index.html http://www.solverfoundation.com/ I contacted both vendors to get their perspectives.   Heres what the Excel Solver guys had to say:   "The Solver Foundation requires you to learn and use a very specific modeling language (OML). The Excel solver allows you to formulate your optimization problems without learning any new language simply by entering the formulas into cells on the Excel spreadsheet, something that nearly everyone is already familiar with doing.   The Excel Solver also allows you to seamlessly upgrade to products that combine Monte Carlo Simulation capabilities (our Risk Solver Premium and Risk Solver Platform products) which allow you to include uncertainty into your models when appropriate.   Our advanced Excel Solver Products also have a number of built in reporting tools for advanced analysis of the your model and it's results"           And Heres what the Microsoft Solver Foundation guys had to say:   "  With the release of Solver Foundation 3.0, Solver Foundation has the same kinds of solvers (plus a few more) than what is found in Excel Solver. I think there are two main differences:   1.      Problems are described differently. In Excel Solver the goals and constraints are specified inside the spreadsheet, in formulas. In Solver Foundation they are described either in .Net code that uses the Solver Foundation Services API, or using the OML modeling language in Excel. 2.      Solver Foundation’s primary strength is on solving large linear, mixed integer, and constraint models. That is, models that contain arbitrary nonlinear functions (such as trig functions, IF(), powers, etc) are handled a bit better by the Excel Solver at this point. "

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• Game of Phones

  - by Carlos Chang

  Game  of  Phones There’s an excellent DZone article titled: 2014 Guide to Mobile Development. It’s loaded with excellent information including some results from a mobile related survey to more than 1000 IT professionals. Without giving away too much, these highlights should convince you to read the entire article.  Web and Hybrid apps are gaining tons of traction particularly in the enterprise. If you want to better understand the differences between Web, Native and Hybrid, this article has you covered. Enterprise developers are increasingly more interested in cross platform tools. Makes sense right?  I mean, unless you have infinite resources (e.g. Facebook) and can afford to write native apps to every platform, finding something that can meet your needs for iOS and Android makes sense.  And toss in the possibility of Windows Phone …and oh, just to be current, the addition of Apple’s new mobile language, Swift, to add to Objective C.. and oh boy.  Why not check out cross platform tools? BTW, don’t  forget testing on each platform, and maintenance and the next versions of the app. It’s not one and done. If you’re successful, you’re never done. Various mobile vendors are represented and many provide some great information.  Oracle's own Suhas Uliyar, VP of Mobile Strategy, represented with some great insights into the challenges of mobile back end integration (SOA, mBaaS, etc.) and moving from "mobile first" to a mobile plus world. BTW, Suhas was recently named Top 100 Wireless Technology Experts for 2014 by Today's Wireless World magazine.  And if your not yet convinced, DZone did a very nice job with their mobile infographic stylized after the insanely popular series, Game of Thrones.  Even though there were no dragons illustrated, worth the price of admission just for that.   Check it out here.

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• Dynamically loading Assemblies to reduce Runtime Depencies

  - by Rick Strahl

  I've been working on a request to the West Wind Application Configuration library to add JSON support. The config library is a very easy to use code-first approach to configuration: You create a class that holds the configuration data that inherits from a base configuration class, and then assign a persistence provider at runtime that determines where and how the configuration data is store. Currently the library supports .NET Configuration stores (web.config/app.config), XML files, SQL records and string storage.About once a week somebody asks me about JSON support and I've deflected this question for the longest time because frankly I think that JSON as a configuration store doesn't really buy a heck of a lot over XML. Both formats require the user to perform some fixup of the plain configuration data - in XML into XML tags, with JSON using JSON delimiters for properties and property formatting rules. Sure JSON is a little less verbose and maybe a little easier to read if you have hierarchical data, but overall the differences are pretty minor in my opinion. And yet - the requests keep rolling in.Hard Link Issues in a Component LibraryAnother reason I've been hesitant is that I really didn't want to pull in a dependency on an external JSON library - in this case JSON.NET - into the core library. If you're not using JSON.NET elsewhere I don't want a user to have to require a hard dependency on JSON.NET unless they want to use the JSON feature. JSON.NET is also sensitive to versions and doesn't play nice with multiple versions when hard linked. For example, when you have a reference to V4.4 in your project but the host application has a reference to version 4.5 you can run into assembly load problems. NuGet's Update-Package can solve some of this *if* you can recompile, but that's not ideal for a component that's supposed to be just plug and play. This is no criticism of JSON.NET - this really applies to any dependency that might change.  So hard linking the DLL can be problematic for a number reasons, but the primary reason is to not force loading of JSON.NET unless you actually need it when you use the JSON configuration features of the library.Enter Dynamic LoadingSo rather than adding an assembly reference to the project, I decided that it would be better to dynamically load the DLL at runtime and then use dynamic typing to access various classes. This allows me to run without a hard assembly reference and allows more flexibility with version number differences now and in the future.But there are also a couple of downsides:No assembly reference means only dynamic access - no compiler type checking or IntellisenseRequirement for the host application to have reference to JSON.NET or else get runtime errorsThe former is minor, but the latter can be problematic. Runtime errors are always painful, but in this case I'm willing to live with this. If you want to use JSON configuration settings JSON.NET needs to be loaded in the project. If this is a Web project, it'll likely be there already.So there are a few things that are needed to make this work:Dynamically create an instance and optionally attempt to load an Assembly (if not loaded)Load types into dynamic variablesUse Reflection for a few tasks like statics/enumsThe dynamic keyword in C# makes the formerly most difficult Reflection part - method calls and property assignments - fairly painless. But as cool as dynamic is it doesn't handle all aspects of Reflection. Specifically it doesn't deal with object activation, truly dynamic (string based) member activation or accessing of non instance members, so there's still a little bit of work left to do with Reflection.Dynamic Object InstantiationThe first step in getting the process rolling is to instantiate the type you need to work with. This might be a two step process - loading the instance from a string value, since we don't have a hard type reference and potentially having to load the assembly. Although the host project might have a reference to JSON.NET, that instance might have not been loaded yet since it hasn't been accessed yet. In ASP.NET this won't be a problem, since ASP.NET preloads all referenced assemblies on AppDomain startup, but in other executable project, assemblies are just in time loaded only when they are accessed.Instantiating a type is a two step process: Finding the type reference and then activating it. Here's the generic code out of my ReflectionUtils library I use for this:/// <summary> /// Creates an instance of a type based on a string. Assumes that the type's /// </summary> /// <param name="typeName">Common name of the type</param> /// <param name="args">Any constructor parameters</param> /// <returns></returns> public static object CreateInstanceFromString(string typeName, params object[] args) { object instance = null; Type type = null; try { type = GetTypeFromName(typeName); if (type == null) return null; instance = Activator.CreateInstance(type, args); } catch { return null; } return instance; } /// <summary> /// Helper routine that looks up a type name and tries to retrieve the /// full type reference in the actively executing assemblies. /// </summary> /// <param name="typeName"></param> /// <returns></returns> public static Type GetTypeFromName(string typeName) { Type type = null; // Let default name binding find it type = Type.GetType(typeName, false); if (type != null) return type; // look through assembly list var assemblies = AppDomain.CurrentDomain.GetAssemblies(); // try to find manually foreach (Assembly asm in assemblies) { type = asm.GetType(typeName, false); if (type != null) break; } return type; } To use this for loading JSON.NET I have a small factory function that instantiates JSON.NET and sets a bunch of configuration settings on the generated object. The startup code also looks for failure and tries loading up the assembly when it fails since that's the main reason the load would fail. Finally it also caches the loaded instance for reuse (according to James the JSON.NET instance is thread safe and quite a bit faster when cached). Here's what the factory function looks like in JsonSerializationUtils:/// <summary> /// Dynamically creates an instance of JSON.NET /// </summary> /// <param name="throwExceptions">If true throws exceptions otherwise returns null</param> /// <returns>Dynamic JsonSerializer instance</returns> public static dynamic CreateJsonNet(bool throwExceptions = true) { if (JsonNet != null) return JsonNet; lock (SyncLock) { if (JsonNet != null) return JsonNet; // Try to create instance dynamic json = ReflectionUtils.CreateInstanceFromString("Newtonsoft.Json.JsonSerializer"); if (json == null) { try { var ass = AppDomain.CurrentDomain.Load("Newtonsoft.Json"); json = ReflectionUtils.CreateInstanceFromString("Newtonsoft.Json.JsonSerializer"); } catch (Exception ex) { if (throwExceptions) throw; return null; } } if (json == null) return null; json.ReferenceLoopHandling = (dynamic) ReflectionUtils.GetStaticProperty("Newtonsoft.Json.ReferenceLoopHandling", "Ignore"); // Enums as strings in JSON dynamic enumConverter = ReflectionUtils.CreateInstanceFromString("Newtonsoft.Json.Converters.StringEnumConverter"); json.Converters.Add(enumConverter); JsonNet = json; } return JsonNet; }This code's purpose is to return a fully configured JsonSerializer instance. As you can see the code tries to create an instance and when it fails tries to load the assembly, and then re-tries loading.Once the instance is loaded some configuration occurs on it. Specifically I set the ReferenceLoopHandling option to not blow up immediately when circular references are encountered. There are a host of other small config setting that might be useful to set, but the default seem to be good enough in recent versions. Note that I'm setting ReferenceLoopHandling which requires an Enum value to be set. There's no real easy way (short of using the cardinal numeric value) to set a property or pass parameters from static values or enums. This means I still need to use Reflection to make this work. I'm using the same ReflectionUtils class I previously used to handle this for me. The function looks up the type and then uses Type.InvokeMember() to read the static property.Another feature I need is have Enum values serialized as strings rather than numeric values which is the default. To do this I can use the StringEnumConverter to convert enums to strings by adding it to the Converters collection.As you can see there's still a bit of Reflection to be done even in C# 4+ with dynamic, but with a few helpers this process is relatively painless.Doing the actual JSON ConversionFinally I need to actually do my JSON conversions. For the Utility class I need serialization that works for both strings and files so I created four methods that handle these tasks two each for serialization and deserialization for string and file.Here's what the File Serialization looks like:/// <summary> /// Serializes an object instance to a JSON file. /// </summary> /// <param name="value">the value to serialize</param> /// <param name="fileName">Full path to the file to write out with JSON.</param> /// <param name="throwExceptions">Determines whether exceptions are thrown or false is returned</param> /// <param name="formatJsonOutput">if true pretty-formats the JSON with line breaks</param> /// <returns>true or false</returns> public static bool SerializeToFile(object value, string fileName, bool throwExceptions = false, bool formatJsonOutput = false) { dynamic writer = null; FileStream fs = null; try { Type type = value.GetType(); var json = CreateJsonNet(throwExceptions); if (json == null) return false; fs = new FileStream(fileName, FileMode.Create); var sw = new StreamWriter(fs, Encoding.UTF8); writer = Activator.CreateInstance(JsonTextWriterType, sw); if (formatJsonOutput) writer.Formatting = (dynamic)Enum.Parse(FormattingType, "Indented"); writer.QuoteChar = '"'; json.Serialize(writer, value); } catch (Exception ex) { Debug.WriteLine("JsonSerializer Serialize error: " + ex.Message); if (throwExceptions) throw; return false; } finally { if (writer != null) writer.Close(); if (fs != null) fs.Close(); } return true; }You can see more of the dynamic invocation in this code. First I grab the dynamic JsonSerializer instance using the CreateJsonNet() method shown earlier which returns a dynamic. I then create a JsonTextWriter and configure a couple of enum settings on it, and then call Serialize() on the serializer instance with the JsonTextWriter that writes the output to disk. Although this code is dynamic it's still fairly short and readable.For full circle operation here's the DeserializeFromFile() version:/// <summary> /// Deserializes an object from file and returns a reference. /// </summary> /// <param name="fileName">name of the file to serialize to</param> /// <param name="objectType">The Type of the object. Use typeof(yourobject class)</param> /// <param name="binarySerialization">determines whether we use Xml or Binary serialization</param> /// <param name="throwExceptions">determines whether failure will throw rather than return null on failure</param> /// <returns>Instance of the deserialized object or null. Must be cast to your object type</returns> public static object DeserializeFromFile(string fileName, Type objectType, bool throwExceptions = false) { dynamic json = CreateJsonNet(throwExceptions); if (json == null) return null; object result = null; dynamic reader = null; FileStream fs = null; try { fs = new FileStream(fileName, FileMode.Open, FileAccess.Read); var sr = new StreamReader(fs, Encoding.UTF8); reader = Activator.CreateInstance(JsonTextReaderType, sr); result = json.Deserialize(reader, objectType); reader.Close(); } catch (Exception ex) { Debug.WriteLine("JsonNetSerialization Deserialization Error: " + ex.Message); if (throwExceptions) throw; return null; } finally { if (reader != null) reader.Close(); if (fs != null) fs.Close(); } return result; }This code is a little more compact since there are no prettifying options to set. Here JsonTextReader is created dynamically and it receives the output from the Deserialize() operation on the serializer.You can take a look at the full JsonSerializationUtils.cs file on GitHub to see the rest of the operations, but the string operations are very similar - the code is fairly repetitive.These generic serialization utilities isolate the dynamic serialization logic that has to deal with the dynamic nature of JSON.NET, and any code that uses these functions is none the wiser that JSON.NET is dynamically loaded.Using the JsonSerializationUtils WrapperThe final consumer of the SerializationUtils wrapper is an actual ConfigurationProvider, that is responsible for handling reading and writing JSON values to and from files. The provider is simple a small wrapper around the SerializationUtils component and there's very little code to make this work now:The whole provider looks like this:/// <summary> /// Reads and Writes configuration settings in .NET config files and /// sections. Allows reading and writing to default or external files /// and specification of the configuration section that settings are /// applied to. /// </summary> public class JsonFileConfigurationProvider<TAppConfiguration> : ConfigurationProviderBase<TAppConfiguration> where TAppConfiguration: AppConfiguration, new() { /// <summary> /// Optional - the Configuration file where configuration settings are /// stored in. If not specified uses the default Configuration Manager /// and its default store. /// </summary> public string JsonConfigurationFile { get { return _JsonConfigurationFile; } set { _JsonConfigurationFile = value; } } private string _JsonConfigurationFile = string.Empty; public override bool Read(AppConfiguration config) { var newConfig = JsonSerializationUtils.DeserializeFromFile(JsonConfigurationFile, typeof(TAppConfiguration)) as TAppConfiguration; if (newConfig == null) { if(Write(config)) return true; return false; } DecryptFields(newConfig); DataUtils.CopyObjectData(newConfig, config, "Provider,ErrorMessage"); return true; } /// <summary> /// Return /// </summary> /// <typeparam name="TAppConfig"></typeparam> /// <returns></returns> public override TAppConfig Read<TAppConfig>() { var result = JsonSerializationUtils.DeserializeFromFile(JsonConfigurationFile, typeof(TAppConfig)) as TAppConfig; if (result != null) DecryptFields(result); return result; } /// <summary> /// Write configuration to XmlConfigurationFile location /// </summary> /// <param name="config"></param> /// <returns></returns> public override bool Write(AppConfiguration config) { EncryptFields(config); bool result = JsonSerializationUtils.SerializeToFile(config, JsonConfigurationFile,false,true); // Have to decrypt again to make sure the properties are readable afterwards DecryptFields(config); return result; } }This incidentally demonstrates how easy it is to create a new provider for the West Wind Application Configuration component. Simply implementing 3 methods will do in most cases.Note this code doesn't have any dynamic dependencies - all that's abstracted away in the JsonSerializationUtils(). From here on, serializing JSON is just a matter of calling the static methods on the SerializationUtils class.Already, there are several other places in some other tools where I use JSON serialization this is coming in very handy. With a couple of lines of code I was able to add JSON.NET support to an older AJAX library that I use replacing quite a bit of code that was previously in use. And for any other manual JSON operations (in a couple of apps I use JSON Serialization for 'blob' like document storage) this is also going to be handy.Performance?Some of you might be thinking that using dynamic and Reflection can't be good for performance. And you'd be right… In performing some informal testing it looks like the performance of the native code is nearly twice as fast as the dynamic code. Most of the slowness is attributable to type lookups. To test I created a native class that uses an actual reference to JSON.NET and performance was consistently around 85-90% faster with the referenced code. That being said though - I serialized 10,000 objects in 80ms vs. 45ms so this isn't hardly slouchy. For the configuration component speed is not that important because both read and write operations typically happen once on first access and then every once in a while. But for other operations - say a serializer trying to handle AJAX requests on a Web Server one would be well served to create a hard dependency.Dynamic Loading - Worth it?On occasion dynamic loading makes sense. But there's a price to be paid in added code complexity and a performance hit. But for some operations that are not pivotal to a component or application and only used under certain circumstances dynamic loading can be beneficial to avoid having to ship extra files and loading down distributions. These days when you create new projects in Visual Studio with 30 assemblies before you even add your own code, trying to keep file counts under control seems a good idea. It's not the kind of thing you do on a regular basis, but when needed it can be a useful tool. Hopefully some of you find this information useful…© Rick Strahl, West Wind Technologies, 2005-2013Posted in .NET  C#   Tweet !function(d,s,id){var js,fjs=d.getElementsByTagName(s)[0];if(!d.getElementById(id)){js=d.createElement(s);js.id=id;js.src="//platform.twitter.com/widgets.js";fjs.parentNode.insertBefore(js,fjs);}}(document,"script","twitter-wjs"); (function() { var po = document.createElement('script'); po.type = 'text/javascript'; po.async = true; po.src = 'https://apis.google.com/js/plusone.js'; var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(po, s); })();

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• What is a better abstraction layer for D3D9 and OpenGL vertex data management?

  - by Sam Hocevar

  My rendering code has always been OpenGL. I now need to support a platform that does not have OpenGL, so I have to add an abstraction layer that wraps OpenGL and Direct3D 9. I will support Direct3D 11 later. TL;DR: the differences between OpenGL and Direct3D cause redundancy for the programmer, and the data layout feels flaky. For now, my API works a bit like this. This is how a shader is created: Shader *shader = Shader::Create( " ... GLSL vertex shader ... ", " ... GLSL pixel shader ... ", " ... HLSL vertex shader ... ", " ... HLSL pixel shader ... "); ShaderAttrib a1 = shader->GetAttribLocation("Point", VertexUsage::Position, 0); ShaderAttrib a2 = shader->GetAttribLocation("TexCoord", VertexUsage::TexCoord, 0); ShaderAttrib a3 = shader->GetAttribLocation("Data", VertexUsage::TexCoord, 1); ShaderUniform u1 = shader->GetUniformLocation("WorldMatrix"); ShaderUniform u2 = shader->GetUniformLocation("Zoom"); There is already a problem here: once a Direct3D shader is compiled, there is no way to query an input attribute by its name; apparently only the semantics stay meaningful. This is why GetAttribLocation has these extra arguments, which get hidden in ShaderAttrib. Now this is how I create a vertex declaration and two vertex buffers: VertexDeclaration *decl = VertexDeclaration::Create( VertexStream<vec3,vec2>(VertexUsage::Position, 0, VertexUsage::TexCoord, 0), VertexStream<vec4>(VertexUsage::TexCoord, 1)); VertexBuffer *vb1 = new VertexBuffer(NUM * (sizeof(vec3) + sizeof(vec2)); VertexBuffer *vb2 = new VertexBuffer(NUM * sizeof(vec4)); Another problem: the information VertexUsage::Position, 0 is totally useless to the OpenGL/GLSL backend because it does not care about semantics. Once the vertex buffers have been filled with or pointed at data, this is the rendering code: shader->Bind(); shader->SetUniform(u1, GetWorldMatrix()); shader->SetUniform(u2, blah); decl->Bind(); decl->SetStream(vb1, a1, a2); decl->SetStream(vb2, a3); decl->DrawPrimitives(VertexPrimitive::Triangle, NUM / 3); decl->Unbind(); shader->Unbind(); You see that decl is a bit more than just a D3D-like vertex declaration, it kinda takes care of rendering as well. Does this make sense at all? What would be a cleaner design? Or a good source of inspiration?

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• BPEL 11.1.1.6 Certified for Prebuilt E-Business Suite 12.1.3 SOA Integrations

  - by Steven Chan (Oracle Development)

  Service Oriented Architecture (SOA) integrations with Oracle E-Business Suite can either be custom integrations that you build yourself or prebuilt integrations from Oracle.  For more information about the differences between the two options for SOA integrations, see this previously-published certification announcement. There are five prebuilt BPEL business processes by Oracle E-Business Suite Release 12 product teams: Oracle Price Protection (DPP) Complex Maintenance, Repair & Overhaul (CMRO/AHL) Oracle Transportation Management (WMS, WSH, PO) Advanced Supply Chain Planning (MSC) Product Information Management (PIM/EGO) Last year we announced the certification of BPEL 11.1.1.5 for Prebuilt E-Business Suite 12.1.3 SOA integrations.  The five prebuilt BPEL processes have now been certified with Oracle BPEL Process Manager 11g version 11.1.1.6 (in Oracle Fusion Middleware SOA Suite 11g).  These prebuilt BPEL processes are certified with Oracle E-Business Suite Release 12.1.3 and higher. Note: The Supply Chain Trading Connector (CLN) product team has opted not to support BPEL 11g with their prebuilt business processes previously certified with BPEL 10.1.3.5.  If you have a requirement for that certification, I would recommend contacting your Oracle account manager to ensure that the Supply Chain team is notified appropriately.  For additional information about prebuilt integrations with Oracle E-Business Suite Release 12.1.3, please refer to the following documentation: Integrating Oracle E-Business Suite Release 12 with Oracle BPEL available in Oracle SOA Suite 11g (Note 1321776.1) Oracle Fusion Middleware 11g (11.1.1.6.0) Documentation Library Installing Oracle SOA Suite and Oracle Business Process Management Suite Release Notes for Oracle Fusion Middleware 11g (11.1.1.6) Certified Platforms Linux x86 (Oracle Linux 4, 5) Linux x86 (RHEL 5) Linux x86 (SLES 10) Linux x86-64 (Oracle Linux 4, 5, 6) Linux x86-64 (RHEL 5) Linux x86-64 (SLES 10)  Oracle Solaris on SPARC (64-bit) (9, 10, 11) HP-UX Itanium (11.23, 11.31) HP-UX PA-RISC (64-bit) (11.23, 11.31) IBM AIX on Power Systems (64-bit) (5.3, 6.1, 7) IBM: Linux on System z (RHEL 5, SLES 10) Microsoft Windows Server (32-bit) (2003, 2008)  Microsoft Windows x64 (64-bit) (2008 R2) Getting SupportIf you need support for the prebuilt EBS 12.1.3 BPEL business processes, you can log Service Requests against the Applications Technology Group product family. Related Articles BPEL 11.1.1.5 Certified for Prebuilt E-Business Suite 12.1.3 SOA Integrations Webcast Replay Available: SOA Integration Options for E-Business Suite Securing E-Business Suite Web Services with Integrated SOA Gateway

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• Dynamically loading Assemblies to reduce Runtime Dependencies

  - by Rick Strahl

  I've been working on a request to the West Wind Application Configuration library to add JSON support. The config library is a very easy to use code-first approach to configuration: You create a class that holds the configuration data that inherits from a base configuration class, and then assign a persistence provider at runtime that determines where and how the configuration data is store. Currently the library supports .NET Configuration stores (web.config/app.config), XML files, SQL records and string storage.About once a week somebody asks me about JSON support and I've deflected this question for the longest time because frankly I think that JSON as a configuration store doesn't really buy a heck of a lot over XML. Both formats require the user to perform some fixup of the plain configuration data - in XML into XML tags, with JSON using JSON delimiters for properties and property formatting rules. Sure JSON is a little less verbose and maybe a little easier to read if you have hierarchical data, but overall the differences are pretty minor in my opinion. And yet - the requests keep rolling in.Hard Link Issues in a Component LibraryAnother reason I've been hesitant is that I really didn't want to pull in a dependency on an external JSON library - in this case JSON.NET - into the core library. If you're not using JSON.NET elsewhere I don't want a user to have to require a hard dependency on JSON.NET unless they want to use the JSON feature. JSON.NET is also sensitive to versions and doesn't play nice with multiple versions when hard linked. For example, when you have a reference to V4.4 in your project but the host application has a reference to version 4.5 you can run into assembly load problems. NuGet's Update-Package can solve some of this *if* you can recompile, but that's not ideal for a component that's supposed to be just plug and play. This is no criticism of JSON.NET - this really applies to any dependency that might change.  So hard linking the DLL can be problematic for a number reasons, but the primary reason is to not force loading of JSON.NET unless you actually need it when you use the JSON configuration features of the library.Enter Dynamic LoadingSo rather than adding an assembly reference to the project, I decided that it would be better to dynamically load the DLL at runtime and then use dynamic typing to access various classes. This allows me to run without a hard assembly reference and allows more flexibility with version number differences now and in the future.But there are also a couple of downsides:No assembly reference means only dynamic access - no compiler type checking or IntellisenseRequirement for the host application to have reference to JSON.NET or else get runtime errorsThe former is minor, but the latter can be problematic. Runtime errors are always painful, but in this case I'm willing to live with this. If you want to use JSON configuration settings JSON.NET needs to be loaded in the project. If this is a Web project, it'll likely be there already.So there are a few things that are needed to make this work:Dynamically create an instance and optionally attempt to load an Assembly (if not loaded)Load types into dynamic variablesUse Reflection for a few tasks like statics/enumsThe dynamic keyword in C# makes the formerly most difficult Reflection part - method calls and property assignments - fairly painless. But as cool as dynamic is it doesn't handle all aspects of Reflection. Specifically it doesn't deal with object activation, truly dynamic (string based) member activation or accessing of non instance members, so there's still a little bit of work left to do with Reflection.Dynamic Object InstantiationThe first step in getting the process rolling is to instantiate the type you need to work with. This might be a two step process - loading the instance from a string value, since we don't have a hard type reference and potentially having to load the assembly. Although the host project might have a reference to JSON.NET, that instance might have not been loaded yet since it hasn't been accessed yet. In ASP.NET this won't be a problem, since ASP.NET preloads all referenced assemblies on AppDomain startup, but in other executable project, assemblies are just in time loaded only when they are accessed.Instantiating a type is a two step process: Finding the type reference and then activating it. Here's the generic code out of my ReflectionUtils library I use for this:/// <summary> /// Creates an instance of a type based on a string. Assumes that the type's /// </summary> /// <param name="typeName">Common name of the type</param> /// <param name="args">Any constructor parameters</param> /// <returns></returns> public static object CreateInstanceFromString(string typeName, params object[] args) { object instance = null; Type type = null; try { type = GetTypeFromName(typeName); if (type == null) return null; instance = Activator.CreateInstance(type, args); } catch { return null; } return instance; } /// <summary> /// Helper routine that looks up a type name and tries to retrieve the /// full type reference in the actively executing assemblies. /// </summary> /// <param name="typeName"></param> /// <returns></returns> public static Type GetTypeFromName(string typeName) { Type type = null; // Let default name binding find it type = Type.GetType(typeName, false); if (type != null) return type; // look through assembly list var assemblies = AppDomain.CurrentDomain.GetAssemblies(); // try to find manually foreach (Assembly asm in assemblies) { type = asm.GetType(typeName, false); if (type != null) break; } return type; } To use this for loading JSON.NET I have a small factory function that instantiates JSON.NET and sets a bunch of configuration settings on the generated object. The startup code also looks for failure and tries loading up the assembly when it fails since that's the main reason the load would fail. Finally it also caches the loaded instance for reuse (according to James the JSON.NET instance is thread safe and quite a bit faster when cached). Here's what the factory function looks like in JsonSerializationUtils:/// <summary> /// Dynamically creates an instance of JSON.NET /// </summary> /// <param name="throwExceptions">If true throws exceptions otherwise returns null</param> /// <returns>Dynamic JsonSerializer instance</returns> public static dynamic CreateJsonNet(bool throwExceptions = true) { if (JsonNet != null) return JsonNet; lock (SyncLock) { if (JsonNet != null) return JsonNet; // Try to create instance dynamic json = ReflectionUtils.CreateInstanceFromString("Newtonsoft.Json.JsonSerializer"); if (json == null) { try { var ass = AppDomain.CurrentDomain.Load("Newtonsoft.Json"); json = ReflectionUtils.CreateInstanceFromString("Newtonsoft.Json.JsonSerializer"); } catch (Exception ex) { if (throwExceptions) throw; return null; } } if (json == null) return null; json.ReferenceLoopHandling = (dynamic) ReflectionUtils.GetStaticProperty("Newtonsoft.Json.ReferenceLoopHandling", "Ignore"); // Enums as strings in JSON dynamic enumConverter = ReflectionUtils.CreateInstanceFromString("Newtonsoft.Json.Converters.StringEnumConverter"); json.Converters.Add(enumConverter); JsonNet = json; } return JsonNet; }This code's purpose is to return a fully configured JsonSerializer instance. As you can see the code tries to create an instance and when it fails tries to load the assembly, and then re-tries loading.Once the instance is loaded some configuration occurs on it. Specifically I set the ReferenceLoopHandling option to not blow up immediately when circular references are encountered. There are a host of other small config setting that might be useful to set, but the default seem to be good enough in recent versions. Note that I'm setting ReferenceLoopHandling which requires an Enum value to be set. There's no real easy way (short of using the cardinal numeric value) to set a property or pass parameters from static values or enums. This means I still need to use Reflection to make this work. I'm using the same ReflectionUtils class I previously used to handle this for me. The function looks up the type and then uses Type.InvokeMember() to read the static property.Another feature I need is have Enum values serialized as strings rather than numeric values which is the default. To do this I can use the StringEnumConverter to convert enums to strings by adding it to the Converters collection.As you can see there's still a bit of Reflection to be done even in C# 4+ with dynamic, but with a few helpers this process is relatively painless.Doing the actual JSON ConversionFinally I need to actually do my JSON conversions. For the Utility class I need serialization that works for both strings and files so I created four methods that handle these tasks two each for serialization and deserialization for string and file.Here's what the File Serialization looks like:/// <summary> /// Serializes an object instance to a JSON file. /// </summary> /// <param name="value">the value to serialize</param> /// <param name="fileName">Full path to the file to write out with JSON.</param> /// <param name="throwExceptions">Determines whether exceptions are thrown or false is returned</param> /// <param name="formatJsonOutput">if true pretty-formats the JSON with line breaks</param> /// <returns>true or false</returns> public static bool SerializeToFile(object value, string fileName, bool throwExceptions = false, bool formatJsonOutput = false) { dynamic writer = null; FileStream fs = null; try { Type type = value.GetType(); var json = CreateJsonNet(throwExceptions); if (json == null) return false; fs = new FileStream(fileName, FileMode.Create); var sw = new StreamWriter(fs, Encoding.UTF8); writer = Activator.CreateInstance(JsonTextWriterType, sw); if (formatJsonOutput) writer.Formatting = (dynamic)Enum.Parse(FormattingType, "Indented"); writer.QuoteChar = '"'; json.Serialize(writer, value); } catch (Exception ex) { Debug.WriteLine("JsonSerializer Serialize error: " + ex.Message); if (throwExceptions) throw; return false; } finally { if (writer != null) writer.Close(); if (fs != null) fs.Close(); } return true; }You can see more of the dynamic invocation in this code. First I grab the dynamic JsonSerializer instance using the CreateJsonNet() method shown earlier which returns a dynamic. I then create a JsonTextWriter and configure a couple of enum settings on it, and then call Serialize() on the serializer instance with the JsonTextWriter that writes the output to disk. Although this code is dynamic it's still fairly short and readable.For full circle operation here's the DeserializeFromFile() version:/// <summary> /// Deserializes an object from file and returns a reference. /// </summary> /// <param name="fileName">name of the file to serialize to</param> /// <param name="objectType">The Type of the object. Use typeof(yourobject class)</param> /// <param name="binarySerialization">determines whether we use Xml or Binary serialization</param> /// <param name="throwExceptions">determines whether failure will throw rather than return null on failure</param> /// <returns>Instance of the deserialized object or null. Must be cast to your object type</returns> public static object DeserializeFromFile(string fileName, Type objectType, bool throwExceptions = false) { dynamic json = CreateJsonNet(throwExceptions); if (json == null) return null; object result = null; dynamic reader = null; FileStream fs = null; try { fs = new FileStream(fileName, FileMode.Open, FileAccess.Read); var sr = new StreamReader(fs, Encoding.UTF8); reader = Activator.CreateInstance(JsonTextReaderType, sr); result = json.Deserialize(reader, objectType); reader.Close(); } catch (Exception ex) { Debug.WriteLine("JsonNetSerialization Deserialization Error: " + ex.Message); if (throwExceptions) throw; return null; } finally { if (reader != null) reader.Close(); if (fs != null) fs.Close(); } return result; }This code is a little more compact since there are no prettifying options to set. Here JsonTextReader is created dynamically and it receives the output from the Deserialize() operation on the serializer.You can take a look at the full JsonSerializationUtils.cs file on GitHub to see the rest of the operations, but the string operations are very similar - the code is fairly repetitive.These generic serialization utilities isolate the dynamic serialization logic that has to deal with the dynamic nature of JSON.NET, and any code that uses these functions is none the wiser that JSON.NET is dynamically loaded.Using the JsonSerializationUtils WrapperThe final consumer of the SerializationUtils wrapper is an actual ConfigurationProvider, that is responsible for handling reading and writing JSON values to and from files. The provider is simple a small wrapper around the SerializationUtils component and there's very little code to make this work now:The whole provider looks like this:/// <summary> /// Reads and Writes configuration settings in .NET config files and /// sections. Allows reading and writing to default or external files /// and specification of the configuration section that settings are /// applied to. /// </summary> public class JsonFileConfigurationProvider<TAppConfiguration> : ConfigurationProviderBase<TAppConfiguration> where TAppConfiguration: AppConfiguration, new() { /// <summary> /// Optional - the Configuration file where configuration settings are /// stored in. If not specified uses the default Configuration Manager /// and its default store. /// </summary> public string JsonConfigurationFile { get { return _JsonConfigurationFile; } set { _JsonConfigurationFile = value; } } private string _JsonConfigurationFile = string.Empty; public override bool Read(AppConfiguration config) { var newConfig = JsonSerializationUtils.DeserializeFromFile(JsonConfigurationFile, typeof(TAppConfiguration)) as TAppConfiguration; if (newConfig == null) { if(Write(config)) return true; return false; } DecryptFields(newConfig); DataUtils.CopyObjectData(newConfig, config, "Provider,ErrorMessage"); return true; } /// <summary> /// Return /// </summary> /// <typeparam name="TAppConfig"></typeparam> /// <returns></returns> public override TAppConfig Read<TAppConfig>() { var result = JsonSerializationUtils.DeserializeFromFile(JsonConfigurationFile, typeof(TAppConfig)) as TAppConfig; if (result != null) DecryptFields(result); return result; } /// <summary> /// Write configuration to XmlConfigurationFile location /// </summary> /// <param name="config"></param> /// <returns></returns> public override bool Write(AppConfiguration config) { EncryptFields(config); bool result = JsonSerializationUtils.SerializeToFile(config, JsonConfigurationFile,false,true); // Have to decrypt again to make sure the properties are readable afterwards DecryptFields(config); return result; } }This incidentally demonstrates how easy it is to create a new provider for the West Wind Application Configuration component. Simply implementing 3 methods will do in most cases.Note this code doesn't have any dynamic dependencies - all that's abstracted away in the JsonSerializationUtils(). From here on, serializing JSON is just a matter of calling the static methods on the SerializationUtils class.Already, there are several other places in some other tools where I use JSON serialization this is coming in very handy. With a couple of lines of code I was able to add JSON.NET support to an older AJAX library that I use replacing quite a bit of code that was previously in use. And for any other manual JSON operations (in a couple of apps I use JSON Serialization for 'blob' like document storage) this is also going to be handy.Performance?Some of you might be thinking that using dynamic and Reflection can't be good for performance. And you'd be right… In performing some informal testing it looks like the performance of the native code is nearly twice as fast as the dynamic code. Most of the slowness is attributable to type lookups. To test I created a native class that uses an actual reference to JSON.NET and performance was consistently around 85-90% faster with the referenced code. This will change though depending on the size of objects serialized - the larger the object the more processing time is spent inside the actual dynamically activated components and the less difference there will be. Dynamic code is always slower, but how much it really affects your application primarily depends on how frequently the dynamic code is called in relation to the non-dynamic code executing. In most situations where dynamic code is used 'to get the process rolling' as I do here the overhead is small enough to not matter.All that being said though - I serialized 10,000 objects in 80ms vs. 45ms so this is hardly slouchy performance. For the configuration component speed is not that important because both read and write operations typically happen once on first access and then every once in a while. But for other operations - say a serializer trying to handle AJAX requests on a Web Server one would be well served to create a hard dependency.Dynamic Loading - Worth it?Dynamic loading is not something you need to worry about but on occasion dynamic loading makes sense. But there's a price to be paid in added code  and a performance hit which depends on how frequently the dynamic code is accessed. But for some operations that are not pivotal to a component or application and are only used under certain circumstances dynamic loading can be beneficial to avoid having to ship extra files adding dependencies and loading down distributions. These days when you create new projects in Visual Studio with 30 assemblies before you even add your own code, trying to keep file counts under control seems like a good idea. It's not the kind of thing you do on a regular basis, but when needed it can be a useful option in your toolset… © Rick Strahl, West Wind Technologies, 2005-2013Posted in .NET  C#   Tweet !function(d,s,id){var js,fjs=d.getElementsByTagName(s)[0];if(!d.getElementById(id)){js=d.createElement(s);js.id=id;js.src="//platform.twitter.com/widgets.js";fjs.parentNode.insertBefore(js,fjs);}}(document,"script","twitter-wjs"); (function() { var po = document.createElement('script'); po.type = 'text/javascript'; po.async = true; po.src = 'https://apis.google.com/js/plusone.js'; var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(po, s); })();

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• Understanding Data Science: Recent Studies

  - by Joe Lamantia

  If you need such a deeper understanding of data science than Drew Conway's popular venn diagram model, or Josh Wills' tongue in cheek characterization, "Data Scientist (n.): Person who is better at statistics than any software engineer and better at software engineering than any statistician." two relatively recent studies are worth reading.   'Analyzing the Analyzers,' an O'Reilly e-book by Harlan Harris, Sean Patrick Murphy, and Marck Vaisman, suggests four distinct types of data scientists -- effectively personas, in a design sense -- based on analysis of self-identified skills among practitioners.  The scenario format dramatizes the different personas, making what could be a dry statistical readout of survey data more engaging.  The survey-only nature of the data,  the restriction of scope to just skills, and the suggested models of skill-profiles makes this feel like the sort of exercise that data scientists undertake as an every day task; collecting data, analyzing it using a mix of statistical techniques, and sharing the model that emerges from the data mining exercise.  That's not an indictment, simply an observation about the consistent feel of the effort as a product of data scientists, about data science.  And the paper 'Enterprise Data Analysis and Visualization: An Interview Study' by researchers Sean Kandel, Andreas Paepcke, Joseph Hellerstein, and Jeffery Heer considers data science within the larger context of industrial data analysis, examining analytical workflows, skills, and the challenges common to enterprise analysis efforts, and identifying three archetypes of data scientist.  As an interview-based study, the data the researchers collected is richer, and there's correspondingly greater depth in the synthesis.  The scope of the study included a broader set of roles than data scientist (enterprise analysts) and involved questions of workflow and organizational context for analytical efforts in general.  I'd suggest this is useful as a primer on analytical work and workers in enterprise settings for those who need a baseline understanding; it also offers some genuinely interesting nuggets for those already familiar with discovery work. We've undertaken a considerable amount of research into discovery, analytical work/ers, and data science over the past three years -- part of our programmatic approach to laying a foundation for product strategy and highlighting innovation opportunities -- and both studies complement and confirm much of the direct research into data science that we conducted. There were a few important differences in our findings, which I'll share and discuss in upcoming posts.

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• Access-based Enumeration (December 04, 2009)

  - by user12612012

  Access-based Enumeration (ABE) is another recent addition to the Solaris CIFS Service - delivered into snv_124.  Designed to be compatible with Windows ABE, which was introduced in Windows Server 2003 SP1, this feature filters directory content based on the user browsing the directory.  Each user can only see the files and directories to which they have access.  This can be useful to implement an out-of-sight, out-of-mind policy or simply to reduce the number of files presented to each user - to make it easier to find files in directories containing a large number of files. ABE is managed on a per share basis by a new boolean share property called, as you might imagine, abe, which is described insharemgr(1M).  When set to true, ABE filtering is enabled on the share and directory entries to which the user has no access will be omitted from directory listings returned to the client.  When set to false or not defined, ABE filtering will not be performed on the share.  The abe property is not defined by default.Administration is straightforward, for example: # zfs sharesmb=abe=true,name=jane tank/home/jane# sharemgr show -vp    zfs       zfs/tank/home/jane nfs=() smb=()          jane=/export/home/jane     smb=(abe="true") ABE is also supported via sharemgr(1M) and on smbautohome(4) shares. Note that even though a file is visible in a share, with ABE enabled, it doesn't automatically mean that the user will always be able to open the file.  If a user has read attribute access to a file ABE will show the it but access will be denied if this user tries to open the file for reading or writing. We considered supporting ABE on NFS shares, as suggested by the name of PSARC/2009/375, but we ran into problems due to NFS client readdir caching.  NFS clients maintain a common directory entry cache for all users, which not only defeats the intent of ABE but can lead to very confusing results.  If multiple users are looking at the content of a directory with ABE enabled, the entries that get cached will depend on who looks at the directory first.  Subsequent users may see files that ABE on the server would have filtered out or files may be missing because they were filtered out for the original user. Although this issue can be resolved by disabling the NFS client readdir cache, this was deemed to be an unsuitable solution because it would create a dependency between a server share property and the configuration on all NFS clients, and there was the potential for differences in behavior across the various NFS clients.  It just seemed to add unnecessary administration complexity so we pulled it out. References for more information PSARC/2009/246 ZFS support for Access Based Enumeration PSARC/2009/375 ABE share property for NFS and SMB 6802734 Support for Access Based Enumeration 6802736 SMB share support for Access Based Enumeration Windows Access-based Enumeration

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• CRM vs VRM

  - by David Dorf

  In a previous post, I discussed the potential power of combining social, interest, and location graphs in order to personalize marketing and shopping experiences for consumers.  Marketing companies have been trying to collect detailed information for that very purpose, a large majority of which comes from tracking people on the internet.  But their approaches stem from the one-way nature of traditional advertising.  With TV, radio, and magazines there is no opportunity to truly connect to customers, which has trained marketing companies to [covertly] collect data and segment customers into easily identifiable groups.  To a large extent, we think of this as CRM. But what if we turned this viewpoint upside-down to accommodate for the two-way nature of social media?  The notion of marketing as conversations was the basis for the Cluetrain, an early attempt at drawing attention to the fact that customers are actually unique humans.  A more practical implementation is Project VRM, which is a reverse CRM of sorts.  Instead of vendors managing their relationships with customers, customers manage their relationships with vendors. Your shopping experience is not really controlled by you; rather, its controlled by the retailer and advertisers.  And unfortunately, they typically don't give you a say in the matter.  Yes, they might tailor the content for "female age 25-35 interested in shoes" but that's not really the essence of you, is it?  A better approach is to the let consumers volunteer information about themselves.  And why wouldn't they if it means a better, more relevant shopping experience?  I'd gladly list out my likes and dislikes in exchange for getting rid of all those annoying cookies on my harddrive. I really like this diagram from Beyond SocialCRM as it captures the differences between CRM and VRM. The closest thing to VRM I can find is Buyosphere, a start-up that allows consumers to track their shopping history across many vendors, then share it appropriately.  Also, Amazon does a pretty good job allowing its customers to edit their profile, which includes everything you've ever purchased from Amazon.  You can mark items as gifts, or explicitly exclude them from their recommendation engine.  This is a win-win for both the consumer and retailer. So here is my plea to retailers: Instead of trying to infer my interests from snapshots of my day, please just ask me.  We'll both have a better experience in the long-run.

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• Fonts look squashed or stretched in the browser on Ubuntu

  - by Arjun Menon

  Fonts in the browser on Ubuntu look look squashed/stretched compared to Windows/OSX. This image shows exactly what I mean: http://i.stack.imgur.com/suUXX.png I installed msttcorefonts and configured both Chrome & FF to use Microsoft fonts (Arial, Times New Roman) instead of the default ones. While MS fonts made web pages appear a bit different, regardless of what font it was the squashed/stretched look remained. FreeSans looks a little different from Arial, but it too is rendered squashed/stretched like Arial on both FF & Chrome. Opera renders the Wikipedia page differently from FF & Chrome, but the fonts looks squashed/stretched on it as well. I used to run Kubuntu prior to switching to Ubuntu and at some point I managed to get the fonts on Chrome (only Chrome) look exactly like in the image on the left. I have no idea how I did it though. Firefox and Rekonq retained the squashed/stretched look. I had been using Rekonq for a while, then switched to FF. While using both browsers I had done various things to get the fonts to look better on them with no success - like installing MS fonts & configuring both browsers to use them. I then, after some time, installed Chrome and the fonts magically looked perfect on them - just like on right-hand side of the image. In fact, the font smoothing looked better (to my eye) compared to Windows and OSX. All 3 OSes use subtly different font smoothing strategies and the differences stand out. Later, I formatted & installed Ubuntu 12.04. The first thing I did was install msttcorefonts & then install Chrome. To my dismay, the fonts on Chrome looked just as squashed/stretched as it did in Firefox. There's no browser (except Wine Internet Explorer) that renders fonts properly on my Ubuntu setup right now. Fixing this is definitely possible, since I was able to do it on Kubuntu, but apparently it requires some mysterious tweaking. Would anyone be willing to help me out?

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• New channels for Exadata 11.2.3.1.1

  - by Rene Kundersma

  With the release of Exadata 11.2.3.1.0 back in April 2012 Oracle has deprecated the minimal pack for the Exadata Database Servers (compute nodes). From that release the Linux Database Server updates will be done using ULN and YUM. For the 11.2.3.1.0 release the ULN exadata_dbserver_11.2.3.1.0_x86_64_base channel was made available and Exadata operators could subscribe their system to it via linux.oracle.com. With the new 11.2.3.1.1 release two additional channels are added: a 'latest' channel (exadata_dbserver_11.2_x86_64_latest) a 'patch' channel (exadata_dbserver_11.2_x86_64_patch) The patch channel has the new or updated packages updated in 11.2.3.1.1 from the base channel. The latest channel has all the packages from 11.2.3.1.0 base and patch channels combined.  From here there are three possible situations a Database Server can be in before it can be updated to 11.2.3.1.1: Database Server is on Exadata release < 11.2.3.1.0 Database Server is patched to 11.2.3.1.0 Database Server is freshly imaged to 11.2.3.1.0 In order to bring a Database Server to 11.2.3.1.1 for all three cases the same approach for updating can be used (using YUM), but there are some minor differences: For Database Servers on a release < 11.2.3.1.0 the following high-level steps need to be performed: Subscribe to el5_x86_64_addons, ol5_x86_64_latest and  exadata_dbserver_11.2_x86_64_latest Create local repository Point Database Server to the local repository* install the update * during this process a one-time action needs to be done (details in the README) For Database Servers patched to 11.2.3.1.0: Subscribe to patch channel  exadata_dbserver_11.2_x86_64_patch Create local repository Point Database Server to the local repository Update the system For Database Servers freshly imaged to 11.2.3.1.0: Subscribe to patch channel  exadata_dbserver_11.2_x86_64_patch Create local  repository Point Database Server to the local repository Update the system The difference between 'situation 2' (Database Server is patched to 11.2.3.1.0) and 'situation 3' (Database Server is freshly imaged to 11.2.3.1.0) is that in situation 2 the existing Exadata-computenode.repo file needs to be edited while in situation 3 this file is not existing  and needs to be created or copied. Another difference is that you will end up with more OFA packages installed in situation 2. This is because none are removed during the updating process.  The YUM update functionality with the new channels is a great enhancements to the Database Server update procedure. As usual, the updates can be done in a rolling fashion so no database service downtime is required.  For detailed and up-to-date instructions always see the patch README's 1466459.1 patch 13998727 888828.1 Rene Kundersma

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• WPF Control Toolkits Comparison for LOB Apps

  In preparation for a new WPF project Ive been researching options for WPF Control toolkits.  While we want a lot of the benefits of WPF, the application is a fairly typical line of business application (LOB).  So were not focused on things like media and animations, but instead a simple, solid, intuitive, and modern user interface that allows for well architected separation of business logic and presentation layers. While WPF is mature, it hasnt lived the long life that Winforms has yet, so there is still a lot of room for third party and community control toolkits to fill the gaps between the controls that ship with the Framework.  There are two such gaps I was concerned about.  As this is an LOB app, we have needs for presenting lots of data and not surprisingly much of it is in grid format with the need for high performance, grouping, inline editing, aggregation, printing and exporting and things that weve been doing with LOB apps for a long time.  In addition we want a dashboard style for the UI in which the user can rearrange and shrink and grow tiles that house the content and functionality.  From a cost perspective, building these types of well performing controls from scratch doesnt make sense.  So I evaluated what you get from the .NET Framework along with a few different options for control toolkits.  I tried to be fairly thorough, but know that this isnt a detailed benchmarking comparison or intense evaluation.  Its just meant to be a feature set comparison to be used when thinking about building an LOB app in WPF.  I tried to list important feature differences and notes based on my experience with the trial versions and what I found in documentation and reference materials and samples.  Ive also listed the importance of the controls based on how I think they are needed in LOB apps.  There are several toolkits available, but given I dont have unlimited time, I picked just a few.  Maybe Ill add on more later.  The toolkits I compared are: Teleriks RadControls for WPF since I had heard some good things about Telerik Infragistics NetAdvantage WPF since both I and the customer have some experience with the vendors tools WPF Toolkit on codeplex since many of my colleagues have used it Blacklight codeplex project which had WPF support for the Tile View control  (with Release 4.3 WPF is not going to be supported in favor of focusing only on SilverLight controls, so I dropped that from the comparison) Click Here to Download the WPF Control Toolkits Comparison Hopefully this helps someone out there.  Feel free to post a comment on your experiences or if you think something I listed is incorrect or missing.  Did you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take a look: here.

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• SharePoint 2010, Cloud, and the Constitution

  - by Michael Van Cleave

  The other evening an article on the Red Tap Chronicles caught my eye. The article written by Bob Sullivan titled "The Constitutional Issues of Cloud Computing" was very interesting in regards to the direction most of the technical world is going. We all have been inundated about utilizing cloud computing for reasons of price, availability, or even scalability; but what Bob brings up is a whole separate view of why a business might not want to move toward the cloud for services or applications. The overall point to the article was pretty simple. It all boiled down to the summation that hosting "Things" in the cloud (Email, Documents, etc…) are interpreted differently under the law regarding constitutional search and seizure than say a document or item that is kept in physical form at a business or home. Where if you physically have it stored someone would have to get a warrant to search for it or seize it, but if it is stored off in the cloud and the ISV or provider is subpoenaed for the item then they will usually give access to the information. Obviously this is a big difference in interpretation of the law and the constitution due to technology. So you might ask "Where does this fit in with SharePoint? Well the overall push for this next version of SharePoint is one that gives a business ultimate flexibility to utilize the Cloud. In one example this upcoming version gracefully lends itself to Multi Tenancy so that online or "Cloud" hosting would be possible by Service Providers. Another aspect to the upcoming version is that it has updated its ability to store content outside of the database and in a cheaper commoditized storage facility. This is called Remote Blob Storage (or RBS) which is the next evolution of External Blob Storage (or EBS). With this new functionality that business might look forward to it is extremely important for them to understand that they might be opening themselves up to laws that do not need a warrant to search or seize their information that is stored in the cloud. It will be interesting to see how this all plays out in the next few months. Usually the laws change slowly in comparison to technology so it might be a while until we see if it is actually constitutional to treat someone's content on the cloud differently as it would be in their possession, however until there is some type of parity that happens or more concrete laws regarding the differences be very careful about what you put in the cloud. Michael

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• Picture rendered from above and below using an Orthographic camera do not match

  - by Roy T.

  I'm using an orthographic camera to render slices of a model (in order to voxelize it). I render each slice both from above and below in order to determine what is inside each slice. I am using an orthographic camera The model I render is a simple 'T' shape constructed from two cubes. The cubes have the same dimensions and have the same Y (height) coordinate. See figure 1 for a render of it in Blender. I render this model once directly from above and once directly from below. My expectation was that I would get exactly the same image (except for mirroring over the y-axis). However when I render using a very low resolution render target (25x25) the position (in pixels) of the 'T' is different when rendered from above as opposed to rendered from below. See figure 2 and 3. The pink blocks are not part of the original rendering but I've added them so you can easily count/see the differences. Figure 2: the T rendered from above Figure 3: the T rendered from below This is probably due to what I've read about pixel and texel coordinates which might be biased to the top-left as seen from the camera. Since I'm using the same 'up' vector for both of my camera's my bias only shows on the x-axis. I've tried to change the position of the camera and it's look-at by, what I thought, should be half a pixel. I've tried both shifting a single camera and shifting both cameras and while I see some effect I am not able to get a pixel-by-pixel perfect copy from both camera's. Here I initialize the camera and compute, what I believe to be, half pixel. boundsDimX and boundsDimZ is a slightly enlarged bounding box around the model which I also use as the width and height of the view volume of the orthographic camera. Matrix projection = Matrix.CreateOrthographic(boundsDimX, boundsDimZ, 0.5f, sliceHeight + 0.5f); Vector3 halfPixel = new Vector3(boundsDimX / (float)renderTarget.Width, 0, boundsDimY / (float)renderTarget.Height) * 0.5f; This is the code where I set the camera position and camera look ats // Position camera if (downwards) { float cameraHeight = bounds.Max.Y + 0.501f - (sliceHeight * i); Vector3 cameraPosition = new Vector3 ( boundsCentre.X, // possibly adjust by half a pixel? cameraHeight, boundsCentre.Z ); camera.Position = cameraPosition; camera.LookAt = new Vector3(cameraPosition.X, cameraHeight - 1.0f, cameraPosition.Z); } else { float cameraHeight = bounds.Max.Y - 0.501f - (sliceHeight * i); Vector3 cameraPosition = new Vector3 ( boundsCentre.X, cameraHeight, boundsCentre.Z ); camera.Position = cameraPosition; camera.LookAt = new Vector3(cameraPosition.X, cameraHeight + 1.0f, cameraPosition.Z); } Main Question Now you've seen all the problems and code you can guess it. My main question is. How do I align both camera's so that they each render exactly the same image (mirrored along the Y axis)? Figure 1 the original model rendered in blender

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• links for 2011-03-17

  - by Bob Rhubart

  Siba Prasad: Oracle Database on Amazon RDSg Siba Prasad share an analysis of the pros and cons. (tags: oracle database cloud amazon) LIVE WEBCAST March 24 2pm PT- Why Switch from Red Hat and SUSE Linux to Oracle Linux? (Oracle's Linux Blog) Featuring Oracle's Monica Kumar, Sr.Director of Linux, Oracle VM and MySQL and Avi Miller, Principal Sales Consultant, Linux and Virtualization. (tags: oracle linux) Webcast: IBM SOA vs. Oracle SOA, March 24, 1pm ET / 10am PT Maneesh Joshi and Bruce Tierney guide you to a solid understanding of the differences between the Oracle and IBM approach to comprehensive SOA. (tags: oracle soa bpm) Finding the Right Solution to Source and Manage Your Contractors (PeopleSoft Apps Strategy) "Talent has become a primary competitive advantage for most organizations. Contingent labor offers talent on flexible terms; it offers the ability to scale up operations, close skill gaps, and manage risk in the process of delivering services." - Mark Rosenberg (tags: oracle peoplesoft enterprisearchitecture) Oracle Business Intelligence Customers: Have Your Voice Heard in the "2011Wisdom of the Crowds Business Intelligence Market Survey" (BI & Analytics Pulse) "The Wisdom of the Crowds survey combines social media, crowd sourcing, and good old fashioned market research to provide vendors and customers alike an unvarnished and insightful snap shot of what's top of mind with business intelligence professionals." (tags: oracle businessintelligence) Martin Bach: Troubleshooting Grid Infrastructure startup Martin Bach hunts down the problem that caused one of his blades to reboot after an EXT3 journal error. (tags: oracle grid rac) Oracle WebCenter: Social Networking & Collaboration (Oracle Enterprise 2.0 Blog) Kelley Ruppel with information on "how the new release of Oracle WebCenter provides unprecedented Social Networking and Collaboration." (tags: oracle webcenter enterprise2.0 collaboration) VirtaThon: 100% Virtual Java/Oracle/MySQL Conference! | Bex Huff "The goal is simple," says Oracle ACE Director Bex Huff. "Because it's all online, the conference is very cheap. Pricing is not yet announced... but it should be around $300. Also, unlike other conferences, every speaker gets paid a small fee depending on the popularity of his or her session." (tags: oracle oracleace java mysqql) Griffiths Waite Blog: BPM 11g PS3 GW's Ian Heathcock shares a link to "a most interesting article on Oracle's recent release discussing the new features and how PS3 adds value  to the whole SOA message." (tags: oracle soa) The Buttso Blathers: Tutorial: JSF 2.0 and JPA 2.0 with WebLogic Server using NetBeans Should you take application architecture advice from a man named Buttso? In this case, yes. (tags: oracle jsf jpa weblogic) Setting-up a High Available Tuned SOA Environment Middleware Magic (tags: ping.fm) How to Configure Weblogic Messaging Bridge with JBoss Middleware Magic (tags: ping.fm Weblogic JBoss) Richard Veryard on Architecture: Emergent Architecture (tags: ping.fm entarch emergence)

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