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• Handling inheritance with overriding efficiently

  - by Fyodor Soikin

  I have the following two data structures. First, a list of properties applied to object triples: Object1 Object2 Object3 Property Value O1 O2 O3 P1 "abc" O1 O2 O3 P2 "xyz" O1 O3 O4 P1 "123" O2 O4 O5 P1 "098" Second, an inheritance tree: O1 O2 O4 O3 O5 Or viewed as a relation: Object Parent O2 O1 O4 O2 O3 O1 O5 O3 O1 null The semantics of this being that O2 inherits properties from O1; O4 - from O2 and O1; O3 - from O1; and O5 - from O3 and O1, in that order of precedence. NOTE 1: I have an efficient way to select all children or all parents of a given object. This is currently implemented with left and right indexes, but hierarchyid could also work. This does not seem important right now. NOTE 2: I have tiggers in place that make sure that the "Object" column always contains all possible objects, even when they do not really have to be there (i.e. have no parent or children defined). This makes it possible to use inner joins rather than severely less effiecient outer joins. The objective is: Given a pair of (Property, Value), return all object triples that have that property with that value either defined explicitly or inherited from a parent. NOTE 1: An object triple (X,Y,Z) is considered a "parent" of triple (A,B,C) when it is true that either X = A or X is a parent of A, and the same is true for (Y,B) and (Z,C). NOTE 2: A property defined on a closer parent "overrides" the same property defined on a more distant parent. NOTE 3: When (A,B,C) has two parents - (X1,Y1,Z1) and (X2,Y2,Z2), then (X1,Y1,Z1) is considered a "closer" parent when: (a) X2 is a parent of X1, or (b) X2 = X1 and Y2 is a parent of Y1, or (c) X2 = X1 and Y2 = Y1 and Z2 is a parent of Z1 In other words, the "closeness" in ancestry for triples is defined based on the first components of the triples first, then on the second components, then on the third components. This rule establishes an unambigous partial order for triples in terms of ancestry. For example, given the pair of (P1, "abc"), the result set of triples will be: O1, O2, O3 -- Defined explicitly O1, O2, O5 -- Because O5 inherits from O3 O1, O4, O3 -- Because O4 inherits from O2 O1, O4, O5 -- Because O4 inherits from O2 and O5 inherits from O3 O2, O2, O3 -- Because O2 inherits from O1 O2, O2, O5 -- Because O2 inherits from O1 and O5 inherits from O3 O2, O4, O3 -- Because O2 inherits from O1 and O4 inherits from O2 O3, O2, O3 -- Because O3 inherits from O1 O3, O2, O5 -- Because O3 inherits from O1 and O5 inherits from O3 O3, O4, O3 -- Because O3 inherits from O1 and O4 inherits from O2 O3, O4, O5 -- Because O3 inherits from O1 and O4 inherits from O2 and O5 inherits from O3 O4, O2, O3 -- Because O4 inherits from O1 O4, O2, O5 -- Because O4 inherits from O1 and O5 inherits from O3 O4, O4, O3 -- Because O4 inherits from O1 and O4 inherits from O2 O5, O2, O3 -- Because O5 inherits from O1 O5, O2, O5 -- Because O5 inherits from O1 and O5 inherits from O3 O5, O4, O3 -- Because O5 inherits from O1 and O4 inherits from O2 O5, O4, O5 -- Because O5 inherits from O1 and O4 inherits from O2 and O5 inherits from O3 Note that the triple (O2, O4, O5) is absent from this list. This is because property P1 is defined explicitly for the triple (O2, O4, O5) and this prevents that triple from inheriting that property from (O1, O2, O3). Also note that the triple (O4, O4, O5) is also absent. This is because that triple inherits its value of P1="098" from (O2, O4, O5), because it is a closer parent than (O1, O2, O3). The straightforward way to do it is the following. First, for every triple that a property is defined on, select all possible child triples: select Children1.Id as O1, Children2.Id as O2, Children3.Id as O3, tp.Property, tp.Value from TriplesAndProperties tp -- Select corresponding objects of the triple inner join Objects as Objects1 on Objects1.Id = tp.O1 inner join Objects as Objects2 on Objects2.Id = tp.O2 inner join Objects as Objects3 on Objects3.Id = tp.O3 -- Then add all possible children of all those objects inner join Objects as Children1 on Objects1.Id [isparentof] Children1.Id inner join Objects as Children2 on Objects2.Id [isparentof] Children2.Id inner join Objects as Children3 on Objects3.Id [isparentof] Children3.Id But this is not the whole story: if some triple inherits the same property from several parents, this query will yield conflicting results. Therefore, second step is to select just one of those conflicting results: select * from ( select Children1.Id as O1, Children2.Id as O2, Children3.Id as O3, tp.Property, tp.Value, row_number() over( partition by Children1.Id, Children2.Id, Children3.Id, tp.Property order by Objects1.[depthInTheTree] descending, Objects2.[depthInTheTree] descending, Objects3.[depthInTheTree] descending ) as InheritancePriority from ... (see above) ) where InheritancePriority = 1 The window function row_number() over( ... ) does the following: for every unique combination of objects triple and property, it sorts all values by the ancestral distance from the triple to the parents that the value is inherited from, and then I only select the very first of the resulting list of values. A similar effect can be achieved with a GROUP BY and ORDER BY statements, but I just find the window function semantically cleaner (the execution plans they yield are identical). The point is, I need to select the closest of contributing ancestors, and for that I need to group and then sort within the group. And finally, now I can simply filter the result set by Property and Value. This scheme works. Very reliably and predictably. It has proven to be very powerful for the business task it implements. The only trouble is, it is awfuly slow. One might point out the join of seven tables might be slowing things down, but that is actually not the bottleneck. According to the actual execution plan I'm getting from the SQL Management Studio (as well as SQL Profiler), the bottleneck is the sorting. The problem is, in order to satisfy my window function, the server has to sort by Children1.Id, Children2.Id, Children3.Id, tp.Property, Parents1.[depthInTheTree] descending, Parents2.[depthInTheTree] descending, Parents3.[depthInTheTree] descending, and there can be no indexes it can use, because the values come from a cross join of several tables. EDIT: Per Michael Buen's suggestion (thank you, Michael), I have posted the whole puzzle to sqlfiddle here. One can see in the execution plan that the Sort operation accounts for 32% of the whole query, and that is going to grow with the number of total rows, because all the other operations use indexes. Usually in such cases I would use an indexed view, but not in this case, because indexed views cannot contain self-joins, of which there are six. The only way that I can think of so far is to create six copies of the Objects table and then use them for the joins, thus enabling an indexed view. Did the time come that I shall be reduced to that kind of hacks? The despair sets in.

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• Design by Contract with Microsoft .Net Code Contract

  - by Fredrik N

  I have done some talks on different events and summits about Defensive Programming and Design by Contract, last time was at Cornerstone’s Developer Summit 2010. Next time will be at SweNug (Sweden .Net User Group). I decided to write a blog post about of some stuffs I was talking about. Users are a terrible thing! Protect your self from them ”Human users have a gift for doing the worst possible thing at the worst possible time.” – Michael T. Nygard, Release It! The kind of users Michael T. Nygard are talking about is the users of a system. We also have users that uses our code, the users I’m going to focus on is the users of our code. Me and you and another developers. “Any fool can write code that a computer can understand. Good programmers write code that humans can understand.” – Martin Fowler Good programmers also writes code that humans know how to use, good programmers also make sure software behave in a predictable manner despise inputs or user actions. Design by Contract   Design by Contract (DbC) is a way for us to make a contract between us (the code writer) and the users of our code. It’s about “If you give me this, I promise to give you this”. It’s not about business validations, that is something completely different that should be part of the domain model. DbC is to make sure the users of our code uses it in a correct way, and that we can rely on the contract and write code in a way where we know that the users will follow the contract. It will make it much easier for us to write code with a contract specified. Something like the following code is something we may see often: public void DoSomething(Object value) { value.DoIKnowThatICanDoThis(); } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } Where “value” can be uses directly or passed to other methods and later be used. What some of us can easily forget here is that the “value” can be “null”. We will probably not passing a null value, but someone else that uses our code maybe will do it. I think most of you (including me) have passed “null” into a method because you don’t know if the argument need to be specified to a valid value etc. I bet most of you also have got the “Null reference exception”. Sometimes this “Null reference exception” can be hard and take time to fix, because we need to search among our code to see where the “null” value was passed in etc. Wouldn’t it be much better if we can as early as possible specify that the value can’t not be null, so the users of our code also know it when the users starts to use our code, and before run time execution of the code? This is where DbC comes into the picture. We can use DbC to specify what we need, and by doing so we can rely on the contract when we write our code. So the code above can actually use the DoIKnowThatICanDoThis() method on the value object without being worried that the “value” can be null. The contract between the users of the code and us writing the code, says that the “value” can’t be null.   Pre- and Postconditions   When working with DbC we are specifying pre- and postconditions.  Precondition is a condition that should be met before a query or command is executed. An example of a precondition is: “The Value argument of the method can’t be null”, and we make sure the “value” isn’t null before the method is called. Postcondition is a condition that should be met when a command or query is completed, a postcondition will make sure the result is correct. An example of a postconditon is “The method will return a list with at least 1 item”. Commands an Quires When using DbC, we need to know what a Command and a Query is, because some principles that can be good to follow are based on commands and queries. A Command is something that will not return anything, like the SQL’s CREATE, UPDATE and DELETE. There are two kinds of Commands when using DbC, the Creation commands (for example a Constructor), and Others. Others can for example be a Command to add a value to a list, remove or update a value etc. //Creation commands public Stack(int size) //Other commands public void Push(object value); public void Remove(); .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; }   A Query, is something that will return something, for example an Attribute, Property or a Function, like the SQL’s SELECT.   There are two kinds of Queries, the Basic Queries  (Quires that aren’t based on another queries), and the Derived Queries, queries that is based on another queries. Here is an example of queries of a Stack: //Basic Queries public int Count; public object this[int index] { get; } //Derived Queries //Is related to Count Query public bool IsEmpty() { return Count == 0; } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } To understand about some principles that are good to follow when using DbC, we need to know about the Commands and different Queries. The 6 Principles When working with DbC, it’s advisable to follow some principles to make it easier to define and use contracts. The following DbC principles are: Separate commands and queries. Separate basic queries from derived queries. For each derived query, write a postcondition that specifies what result will be returned, in terms of one or more basic queries. For each command, write a postcondition that specifies the value of every basic query. For every query and command, decide on a suitable precondition. Write invariants to define unchanging properties of objects. Before I will write about each of them I want you to now that I’m going to use .Net 4.0 Code Contract. I will in the rest of the post uses a simple Stack (Yes I know, .Net already have a Stack class) to give you the basic understanding about using DbC. A Stack is a data structure where the first item in, will be the first item out. Here is a basic implementation of a Stack where not contract is specified yet: public class Stack { private object[] _array; //Basic Queries public uint Count; public object this[uint index] { get { return _array[index]; } set { _array[index] = value; } } //Derived Queries //Is related to Count Query public bool IsEmpty() { return Count == 0; } //Is related to Count and this[] Query public object Top() { return this[Count]; } //Creation commands public Stack(uint size) { Count = 0; _array = new object[size]; } //Other commands public void Push(object value) { this[++Count] = value; } public void Remove() { this[Count] = null; Count--; } } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; }   Note: The Stack is implemented in a way to demonstrate the use of Code Contract in a simple way, the implementation may not look like how you would implement it, so don’t think this is the perfect Stack implementation, only used for demonstration.   Before I will go deeper into the principles I will simply mention how we can use the .Net Code Contract. I mention before about pre- and postcondition, is about “Require” something and to “Ensure” something. When using Code Contract, we will use a static class called “Contract” and is located in he “System.Diagnostics.Contracts” namespace. The contract must be specified at the top or our member statement block. To specify a precondition with Code Contract we uses the Contract.Requires method, and to specify a postcondition, we uses the Contract.Ensure method. Here is an example where both a pre- and postcondition are used: public object Top() { Contract.Requires(Count > 0, "Stack is empty"); Contract.Ensures(Contract.Result<object>() == this[Count]); return this[Count]; } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; }   The contract above requires that the Count is greater than 0, if not we can’t get the item at the Top of a Stack. We also Ensures that the results (By using the Contract.Result method, we can specify a postcondition that will check if the value returned from a method is correct) of the Top query is equal to this[Count].   1. Separate Commands and Queries   When working with DbC, it’s important to separate Command and Quires. A method should either be a command that performs an Action, or returning information to the caller, not both. By asking a question the answer shouldn’t be changed. The following is an example of a Command and a Query of a Stack: public void Push(object value) public object Top() .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; }   The Push is a command and will not return anything, just add a value to the Stack, the Top is a query to get the item at the top of the stack.   2. Separate basic queries from derived queries There are two different kinds of queries,  the basic queries that doesn’t rely on another queries, and derived queries that uses a basic query. The “Separate basic queries from derived queries” principle is about about that derived queries can be specified in terms of basic queries. So this principles is more about recognizing that a query is a derived query or a basic query. It will then make is much easier to follow the other principles. The following code shows a basic query and a derived query: //Basic Queries public uint Count; //Derived Queries //Is related to Count Query public bool IsEmpty() { return Count == 0; } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; }   We can see that IsEmpty will use the Count query, and that makes the IsEmpty a Derived query.   3. For each derived query, write a postcondition that specifies what result will be returned, in terms of one or more basic queries.   When the derived query is recognize we can follow the 3ed principle. For each derived query, we can create a postcondition that specifies what result our derived query will return in terms of one or more basic queries. Remember that DbC is about contracts between the users of the code and us writing the code. So we can’t use demand that the users will pass in a valid value, we must also ensure that we will give the users what the users wants, when the user is following our contract. The IsEmpty query of the Stack will use a Count query and that will make the IsEmpty a Derived query, so we should now write a postcondition that specified what results will be returned, in terms of using a basic query and in this case the Count query, //Basic Queries public uint Count; //Derived Queries public bool IsEmpty() { Contract.Ensures(Contract.Result<bool>() == (Count == 0)); return Count == 0; } The Contract.Ensures is used to create a postcondition. The above code will make sure that the results of the IsEmpty (by using the Contract.Result to get the result of the IsEmpty method) is correct, that will say that the IsEmpty will be either true or false based on Count is equal to 0 or not. The postcondition are using a basic query, so the IsEmpty is now following the 3ed principle. We also have another Derived Query, the Top query, it will also need a postcondition and it uses all basic queries. The Result of the Top method must be the same value as the this[] query returns. //Basic Queries public uint Count; public object this[uint index] { get { return _array[index]; } set { _array[index] = value; } } //Derived Queries //Is related to Count and this[] Query public object Top() { Contract.Ensures(Contract.Result<object>() == this[Count]); return this[Count]; } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; }   4. For each command, write a postcondition that specifies the value of every basic query.   For each command we will create a postconditon that specifies the value of basic queries. If we look at the Stack implementation we will have three Commands, one Creation command, the Constructor, and two others commands, Push and Remove. Those commands need a postcondition and they should include basic query to follow the 4th principle. //Creation commands public Stack(uint size) { Contract.Ensures(Count == 0); Count = 0; _array = new object[size]; } //Other commands public void Push(object value) { Contract.Ensures(Count == Contract.OldValue<uint>(Count) + 1); Contract.Ensures(this[Count] == value); this[++Count] = value; } public void Remove() { Contract.Ensures(Count == Contract.OldValue<uint>(Count) - 1); this[Count] = null; Count--; } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; }   As you can see the Create command will Ensures that Count will be 0 when the Stack is created, when a Stack is created there shouldn’t be any items in the stack. The Push command will take a value and put it into the Stack, when an item is pushed into the Stack, the Count need to be increased to know the number of items added to the Stack, and we must also make sure the item is really added to the Stack. The postconditon of the Push method will make sure the that old value of the Count (by using the Contract.OldValue we can get the value a Query has before the method is called)  plus 1 will be equal to the Count query, this is the way we can ensure that the Push will increase the Count with one. We also make sure the this[] query will now contain the item we pushed into the Stack. The Remove method must make sure the Count is decreased by one when the top item is removed from the Stack. The Commands is now following the 4th principle, where each command now have a postcondition that used the value of basic queries. Note: The principle says every basic Query, the Remove only used one Query the Count, it’s because this command can’t use the this[] query because an item is removed, so the only way to make sure an item is removed is to just use the Count query, so the Remove will still follow the principle.   5. For every query and command, decide on a suitable precondition.   We have now focused only on postcondition, now time for some preconditons. The 5th principle is about deciding a suitable preconditon for every query and command. If we starts to look at one of our basic queries (will not go through all Queries and commands here, just some of them) the this[] query, we can’t pass an index that is lower then 1 (.Net arrays and list are zero based, but not the stack in this blog post ;)) and the index can’t be lesser than the number of items in the stack. So here we will need a preconditon. public object this[uint index] { get { Contract.Requires(index >= 1); Contract.Requires(index <= Count); return _array[index]; } } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } Think about the Contract as an documentation about how to use the code in a correct way, so if the contract could be specified elsewhere (not part of the method body), we could simply write “return _array[index]” and there is no need to check if index is greater or lesser than Count, because that is specified in a “contract”. The implementation of Code Contract, requires that the contract is specified in the code. As a developer I would rather have this contract elsewhere (Like Spec#) or implemented in a way Eiffel uses it as part of the language. Now when we have looked at one Query, we can also look at one command, the Remove command (You can see the whole implementation of the Stack at the end of this blog post, where precondition is added to more queries and commands then what I’m going to show in this section). We can only Remove an item if the Count is greater than 0. So we can write a precondition that will require that Count must be greater than 0. public void Remove() { Contract.Requires(Count > 0); Contract.Ensures(Count == Contract.OldValue<uint>(Count) - 1); this[Count] = null; Count--; } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; }   6. Write invariants to define unchanging properties of objects.   The last principle is about making sure the object are feeling great! This is done by using invariants. When using Code Contract we can specify invariants by adding a method with the attribute ContractInvariantMethod, the method must be private or public and can only contains calls to Contract.Invariant. To make sure the Stack feels great, the Stack must have 0 or more items, the Count can’t never be a negative value to make sure each command and queries can be used of the Stack. Here is our invariant for the Stack object: [ContractInvariantMethod] private void ObjectInvariant() { Contract.Invariant(Count >= 0); } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; }   Note: The ObjectInvariant method will be called every time after a Query or Commands is called. Here is the full example using Code Contract:   public class Stack { private object[] _array; //Basic Queries public uint Count; public object this[uint index] { get { Contract.Requires(index >= 1); Contract.Requires(index <= Count); return _array[index]; } set { Contract.Requires(index >= 1); Contract.Requires(index <= Count); _array[index] = value; } } //Derived Queries //Is related to Count Query public bool IsEmpty() { Contract.Ensures(Contract.Result<bool>() == (Count == 0)); return Count == 0; } //Is related to Count and this[] Query public object Top() { Contract.Requires(Count > 0, "Stack is empty"); Contract.Ensures(Contract.Result<object>() == this[Count]); return this[Count]; } //Creation commands public Stack(uint size) { Contract.Requires(size > 0); Contract.Ensures(Count == 0); Count = 0; _array = new object[size]; } //Other commands public void Push(object value) { Contract.Requires(value != null); Contract.Ensures(Count == Contract.OldValue<uint>(Count) + 1); Contract.Ensures(this[Count] == value); this[++Count] = value; } public void Remove() { Contract.Requires(Count > 0); Contract.Ensures(Count == Contract.OldValue<uint>(Count) - 1); this[Count] = null; Count--; } [ContractInvariantMethod] private void ObjectInvariant() { Contract.Invariant(Count >= 0); } } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } Summary By using Design By Contract we can make sure the users are using our code in a correct way, and we must also make sure the users will get the expected results when they uses our code. This can be done by specifying contracts. To make it easy to use Design By Contract, some principles may be good to follow like the separation of commands an queries. With .Net 4.0 we can use the Code Contract feature to specify contracts.

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• Adopting DBVCS

  - by Wes McClure

  Identify early adopters Pick a small project with a small(ish) team.  This can be a legacy application or a green-field application. Strive to find a team of early adopters that will be eager to try something new. Get the team on board! Research Research the tool(s) that you want to use.  Some tools provide all of the features you would need while some only provide a slice of the pie.  DBVCS requires the ability to manage a set of change scripts that update a database from one version to the next.  Ideally a tool can track database versions and automatically apply updates.  The change script generation process can be manual, but having diff tools available to automatically generate it can really reduce the overhead to adoption.  Finally, an automated tool to generate a script file per database object is an added bonus as your version control system can quickly identify what was changed in a commit (add/del/modify), just like with code changes. Don’t settle on just one tool, identify several.  Then work with the team to evaluate the tools.  Have the team do some tests of the following scenarios with each tool: Baseline an existing database: can the migration tool work with legacy databases?  Caution: most migration platforms do not support baselines or have poor support, especially the fad of fluent APIs. Add/drop tables Add/drop procedures/functions/views Alter tables (rename columns, add columns, remove columns) Massage data – migrations sometimes involve changing data types that cannot be implicitly casted and require you to decide how the data is explicitly cast to the new type.  This is a requirement for a migrations platform.  Think about a case where you might want to combine fields, or move a field from one table to another, you wouldn’t want to lose the data. Run the tool via the command line.  If you cannot automate the tool in Continuous Integration what is the point? Create a copy of a database on demand. Backup/restore databases locally. Let the team give feedback and decide together, what tool they would like to try out. My recommendation at this point would be to include TSqlMigrations and RoundHouse as SQL based migration platforms.  In general I would recommend staying away from the fluent platforms as they often lack baseline capabilities and add overhead to learn a new API when SQL is already a very well known DSL.  Code migrations often get messy with procedures/views/functions as these have to be created with SQL and aren’t cross platform anyways.  IMO stick to SQL based migrations. Reconciling Production If your project is a legacy application, you will need to reconcile the current state of production with your development databases.  Find changes in production and bring them down to development, even if they are old and need to be removed.  Once complete, produce a baseline of either dev or prod as they are now in sync.  Commit this to your VCS of choice. Add whatever schema changes tracking mechanism your tool requires to your development database.  This often requires adding a table to track the schema version of that database.  Your tool should support doing this for you.  You can add this table to production when you do your next release. Script out any changes currently in dev.  Remove production artifacts that you brought down during reconciliation.  Add change scripts for any outstanding changes in dev since the last production release.  Commit these to your repository.   Say No to Shared Dev DBs Simply put, you wouldn’t dream of sharing a code checkout, why would you share a development database?  If you have a shared dev database, back it up, distribute the backups and take the shared version offline (including the dev db server once all projects are using DB VCS).  Doing DB VCS with a shared database is bound to cause problems as people won’t be able to easily script out their own changes from those that others are working on.   First prod release Copy prod to your beta/testing environment.  Add the schema changes table (or mechanism) and do a test run of your changes.  If successful you can schedule this to be run on production.   Evaluation After your first release, evaluate the pain points of the process.  Try to find tools or modifications to existing tools to help fix them.  Don’t leave stones unturned, iteratively evolve your tools and practices to make the process as seamless as possible.  This is why I suggest open source alternatives.  Nothing is set in stone, a good example was adding transactional support to TSqlMigrations.  We ran into situations where an update would break a database, so I added a feature to do transactional updates and rollback on errors!  Another good example is generating change scripts.  We have been manually making these for months now.  I found an open source project called Open DB Diff and integrated this with TSqlMigrations.  These were things we just accepted at the time when we began adopting our tool set.  Once we became comfortable with the base functionality, it was time to start automating more of the process.  Just like anything else with development, never be afraid to try to find tools to make your job easier!   Enjoy -Wes

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• What's going on with INETA and the Regional Speakers Bureau?

  - by Chris Williams

  For those of you that have been waiting patiently (and not so patiently) I'm happy to say that we're very near completion on some changes/enhancements/improvements that will allow us to finally go live with the INETA Regional Speakers Bureau. I know quite a few of you have already registered, which is great (though some of you may need to come back and update your info) and we've had a few folks submit requests, mostly in a test capacity, but soon we'll be up and live. Here's how it breaks down. Be sure to read this, because things have changed a bit from when we initially announced it. 1. The majority of our speaker/event funding is going into the Regional Speakers Bureau.  The National Bureau still exists, but it's a good bit smaller than it was before, and it's not an "every group" benefit anymore. We'll be using the National Bureau as more of a strategic task force, targeting high impact events and areas that need some community building love from INETA. These will be identified and handled on a case by case basis, and may include more than just user group events. 2. You're going to get more events per group, per year than you did before. Not only are we focusing more resources on this program, but we're also making a lot of efforts to use it more effectively. With the INETA Regional Speakers Bureau, you should be able to get 2-3 INETA speakers per year, on average. Not every geographical area will have exactly the same experience, but we're doing the best we can. 3. It's not a farm team program for the National Bureau. Unsurprisingly, I managed to offend a number of people when I previously made the comment that the Regional Speakers Bureau program was a farm team or stepping stone to the National Bureau. It was a poor choice of words.  Anyone can participate in the Regional Speakers Bureau, and I look forward to working with all of you. 4. There is assistance for your efforts. The exact final details are still being hammered out, but expect it to look something like this: (all distances listed are based on a round trip) Distances < 120 miles = $0 121 miles - 240 miles = $50 (effectively 1 to 2 hours, each way) 241 miles - 360 miles = $100 (effectively 2 to 3 hours, each way) 361 miles - 480 miles = $200 (effectively 3 to 4 hours, each way) For those of you who travel a lot, we're working on a solution to handle group visits when you're away from home. These will (for now) be handled on a case by case basis. 5. We're going to make it as easy as possible to work with the program. In order to do this, we need a few things from you. For speakers, that means your home address. It also means (maybe) filling out a simple 1 line expense report via the INETA website. For user groups, it means making sure your meeting address is up to date as well. 6. Distances will be automatically calculated from your home of record to the user group event and back. We realize that this is not a perfect solution to every instance, but we're not paying you to speak at an event, and you won't be taxed on this money. It's simply some assistance to make your community efforts easier. Our way of saying thanks for everything you do. 7. Sounds good so far, what's the catch? There's always a catch, right? In this case there are two of them: 1) At this time, Microsoft employees are welcome to use the website to line up speaking engagements with user groups, but are not eligible for financial assistance. 2) Anyone can register and use the website to line up speaking engagements with user groups, however you must receive and maintain a net score of 3+ positive ratings (we're implementing a thumbs up / thumbs down system) in order to receive financial assistance. These ratings are provided by the User Group leaders after the meeting has taken place. 8. Involvement by the User Group leaders is a key factor in the success of this program. Your job isn't done once you request a speaker. After you've had your meeting, it's critical that you go back to the website and take a very small survey. Doing this ensures that the speaker gets rated (and compensated if eligible) and also ensures that you can make another request, since you won't be able to make a new request if you have an old one outstanding. 9. What about Canada? We're definitely working on that. Unfortunately nothing new to report on that front, other than to say that we're trying. So... this is where things stand currently. We're working very quickly to get this in place and get speakers and groups together. If you have any questions, please leave a comment below and I'll answer them as quickly as possible. If I've forgotten anything, or if things change, I'll update it here. Thanks, Chris G. Williams INETA Board of Directors

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• Oracle Delivers Latest Release of Oracle Enterprise Manager 12c

  - by Scott McNeil

  Richer Service Catalog for Database and Middleware as a Service; Enhanced Database and Middleware Management Help Drive Enterprise-Scale Private Cloud Adoption News Summary IT organizations are adopting private clouds as a stepping-stone to business-driven, self-service IT. Successful implementations hinge on the ability to efficiently deploy and manage cloud services at enterprise scale. Having a complete cloud management solution integrated with an enterprise-class technology stack is a fundamental requirement for IT. Oracle Enterprise Manager 12c Release 4 meets that requirement by helping businesses become more agile and responsive, while reducing cost, complexity, and risk. News Facts Oracle Enterprise Manager 12c Release 4, available today, lets organizations rapidly adopt Oracle-based, enterprise-scale private clouds. New capabilities provide advanced technology stack management, secure database administration, and enterprise service governance, enabling Oracle customers and partners to maximize database and application performance and drive innovation using self-service IT platforms. The enhancements have been driven by customers and the growing Oracle Enterprise Manager Ecosystem, comprised of more than 750 Oracle PartnerNetwork (OPN) Specialized partners. Oracle and its partners and customers have built over 140 plug-ins and connectors for Oracle Enterprise Manager. Watch the video highlights. Automation for Broader Cloud Services Oracle Enterprise Manager 12c Release 4 allows for a rapid enterprise-wide adoption of database, middleware and infrastructure services in the private cloud, driven by an enhanced API-enabled service catalog. The release features “push button” style provisioning of complete environments such as SOA and Oracle Active Data Guard, and fast data cloning that enables rapid deployment and testing of enterprise applications. Out-of-the-box capabilities to detect data and configuration vulnerabilities provide enhanced cloud service governance along with greater operational control through a flexible and extensible showback mechanism. Enhanced Database Management A new performance warehouse enables predictive database diagnostics and trend analysis and helps identify database problems before they occur. New enterprise data-governance capabilities enhance security by helping systematically discover and protect sensitive data. Step-by-step orchestration of upgrades with the ability to rollback changes enables faster adoption of Oracle Database 12c. Expanded Fusion Middleware Management A new consolidated view of Oracle Fusion Middleware 12c deployments with a guided management capability lets administrators apply best management practices to diverse middleware environments and identify performance issues quickly. A Java VM Diagnostics as a Service feature allows governed access to diagnostics data for IT workers across multiple disciplines for accelerated DevOps resolutions of defects and performance optimization. New automated provisioning for SOA lets middleware administrators perform mass SOA provisioning with ease. Superior Enterprise-Grade Management Private roles and preferred credentials have been added to Oracle Enterprise Manager to provide additional fine-grained security for organizations with complex access control requirements. A new security console provides a single point of control for managing the security of Oracle Enterprise Manager environments. Support for the latest industry standard SNMP v3 protocol, including encryption, enables more secure heterogeneous management. “Smart monitoring” adapts to observed environmental changes and adds self-management capabilities to help Oracle Enterprise Manager run at peak performance, while demanding less IT supervision. Supporting Quotes “Lawrence Livermore National Laboratory has a strong tradition of technology breakthroughs and leadership. As a member of Oracle’s Customer Advisory Board for Oracle Enterprise Manager, we have consistently provided feedback and guidance in the areas of enterprise-scale cloud, self-diagnosability, and secure administration for the product,” said Tim Frazier, CIO, NIF and Photon Sciences, Lawrence Livermore National Laboratory. “We intend to take advantage of the Release 4 features that support enterprise-scale availability and fine-grained security capabilities for private cloud deployments.” “IDC's most recent CloudTrack survey shows that most enterprises plan to adopt hybrid cloud architectures over the next three years,” said Mary Johnston Turner, Research Vice President, Enterprise System Management Software, IDC. “These organizations plan to deploy a wide range of workloads into cloud environments including mission critical database and middleware services that require high levels of fault tolerance and disaster recovery. Such capabilities were traditionally custom configured for each application but cloud offers the possibility to incorporate such properties within the service definition, enabling organizations to adopt cloud without compromise. With the latest release of Oracle Enterprise Manager 12c, Oracle is providing customers with an out-of-the-box experience for delivering highly-resilient cloud services for databases and applications.” “Since its inception, Oracle has been leading the way in innovative, scalable and high performance solutions for the enterprise. With this release of Oracle Enterprise Manager, we are extending this leadership by providing enterprise-scale capabilities for planning, delivering, and managing private clouds. We call this ‘zero-to-cloud – accelerated.’ These enhancements help our customers to expedite their adoption of cloud computing and prepares them for the next generation of self-service IT,” said Prakash Ramamurthy, senior vice president of Systems and Cloud Management at Oracle. Supporting Resources Oracle Enterprise Manager 12c Video: Cerner Delivers High Performance Private Cloud Video: BIAS Achieves Outstanding Results with Private Cloud Press Release Stay Connected: Twitter | Facebook | YouTube | Linkedin | Newsletter Download the Oracle Enterprise Manager 12c Mobile app

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• How Estimates Became Quotes

  - by Lee Brandt

  It’s our fault. Well, not completely, but we haven’t helped the situation any. All of what follows comes from my own experiences which, from talking to lots of other developers about it, seems to be pretty much par for the course. Where We Started When we first started estimating, we estimated pretty clearly. We would try to imagine something we’d done that was similar to the project being estimated and we’d toss it about in our heads a bit and see how much bigger or smaller we thought this new thing was, and add or subtract accordingly. We wouldn’t spend too much time on it, because we wanted to get to writing the software. Eventually, we’d come across some huge problem that there was now way we could’ve known about ahead of time. Either we didn’t see this thing or, we didn’t realize that this particular version of a problem would be so… problematic. We usually call this “not knowing what we don’t know”. It’s unavoidable. We just can’t know. Until we wade in and start putting some code together, there are just some things we won’t know… and some things we don’t even know that we don’t know. Y’know? So what happens? We go over budget. Project managers scream and dance the dance of the stressed-out project manager, and there is nothing we can do (or could’ve done) about it. We didn’t know. We thought about it for a bit and we didn’t see this herculean task sitting in the middle of our nice quiet project, and it has bitten us in the rear end. We now know how to handle this in the future, though. We will take some more time to pick around the requirements and discover all those things we don’t know. We’ll do some prototyping, we’ll read some blogs about similar projects, we’ll really grill the customer with questions during the requirements gathering phase. We’ll keeping asking “what else?” until the shove us down the stairs. We’ll take our time and uncover it all. We Learned, But Good The next time comes, and you know what happens? We do it. We grill the customer for weeks and prototype and read and research and we estimate everything down to the last button on the last form. Know what that gets us? It gets us three months of wasted time, and our estimate will still be off. Possibly off by a factor of four. WTF, mate? No way we could be surprised by something! We uncovered every particle. We turned every stone. How is it we still came across unknowns? Because we STILL didn’t know what we didn’t know. How could we? We didn’t know to ask. The worst part is, we’ve now convinced the product that this is NOT an estimate. It is a solid number based on massive research and an endless number of questions that they answered. There is absolutely now way you don’t know everything there is to know about this project now. No way there is anything you haven’t uncovered. And their faith in that “Esti-Quote” goes through the roof. When the project goes over this time, they might even begin to question whether or not you know what you’re doing. Who could blame them? You drilled them for weeks about every little thing, and when they complained about all the questions, you told them you wanted to uncover everything so there would be no surprises. SO we set them up to faile Guess, Then Plan We had a chance. At the beginning we could have just said, “That’s just a gut-feeling estimate, based on my past experience with similar projects. There could still be surprises.” If we spend SOME time doing SOME discovery and then bounce that against our own past experiences, we can come up with a fairly healthy estimate. We can then help the product owner understand that an estimate is a guess. Sure, it’s an educated guess, but it is still a guess. If we get it right it will be almost completely luck. Then, we help them to plan the development by taking that guess (yes, they still need the guess for planning purposes) and start measuring early and often to see if we still think we are right. We should adjust the estimate and alert the product owner as soon as we see problems (bad news does not age well) and we should be able to see any problems immediately if we are constantly measuring our pace. In lean software, we start with that guess and begin measuring cycle times immediately. Then we can make projections based on those cycle times and compare them to our estimate. This constant feedback is the best way to ensure that there are no surprises at the END of the project. There sill still be surprises, but we’ll see them sooner and have a better understanding of how they will affect our overall timeline. What do you think?

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• Libnoise producing completely random noise

  - by Doodlemeat

  I am using libnoise in C++ taken and I have some problems with getting coherent noise. I mean, the noise produced now are completely random and it doesn't look like a noise. Here's a to the image produced by my game. I am diving the map into several chunks, but I can't seem to find any problem doing that since libnoise supports tileable noise. The code can be found below. Every chunk is 8x8 tiles large. Every tile is 64x64 pixels. I am also providing a link to download the entire project. It was made in Visual Studio 2013. Download link This is the code for generating a chunk Chunk *World::loadChunk(sf::Vector2i pPosition) { sf::Vector2i chunkPos = pPosition; pPosition.x *= mChunkTileSize.x; pPosition.y *= mChunkTileSize.y; sf::FloatRect bounds(static_cast<sf::Vector2f>(pPosition), sf::Vector2f(static_cast<float>(mChunkTileSize.x), static_cast<float>(mChunkTileSize.y))); utils::NoiseMap heightMap; utils::NoiseMapBuilderPlane heightMapBuilder; heightMapBuilder.SetSourceModule(mNoiseModule); heightMapBuilder.SetDestNoiseMap(heightMap); heightMapBuilder.SetDestSize(mChunkTileSize.x, mChunkTileSize.y); heightMapBuilder.SetBounds(bounds.left, bounds.left + bounds.width - 1, bounds.top, bounds.top + bounds.height - 1); heightMapBuilder.Build(); Chunk *chunk = new Chunk(this); chunk->setPosition(chunkPos); chunk->buildChunk(&heightMap); chunk->setTexture(&mTileset); mChunks.push_back(chunk); return chunk; } This is the code for building the chunk void Chunk::buildChunk(utils::NoiseMap *pHeightMap) { // Resize the tiles space mTiles.resize(pHeightMap->GetWidth()); for (int x = 0; x < mTiles.size(); x++) { mTiles[x].resize(pHeightMap->GetHeight()); } // Set vertices type and size mVertices.setPrimitiveType(sf::Quads); mVertices.resize(pHeightMap->GetWidth() * pHeightMap->GetWidth() * 4); // Get the offset position of all tiles position sf::Vector2i tileSize = mWorld->getTileSize(); sf::Vector2i chunkSize = mWorld->getChunkSize(); sf::Vector2f offsetPositon = sf::Vector2f(mPosition); offsetPositon.x *= chunkSize.x; offsetPositon.y *= chunkSize.y; // Build tiles for (int x = 0; x < mTiles.size(); x++) { for (int y = 0; y < mTiles[x].size(); y++) { // Sometimes libnoise can return a value over 1.0, better be sure to cap the top and bottom.. float heightValue = pHeightMap->GetValue(x, y); if (heightValue > 1.f) heightValue = 1.f; if (heightValue < -1.f) heightValue = -1.f; // Instantiate a new Tile object with the noise value, this doesn't do anything yet.. mTiles[x][y] = new Tile(this, pHeightMap->GetValue(x, y)); // Get a pointer to the current tile's quad sf::Vertex *quad = &mVertices[(y + x * pHeightMap->GetWidth()) * 4]; quad[0].position = sf::Vector2f(offsetPositon.x + x * tileSize.x, offsetPositon.y + y * tileSize.y); quad[1].position = sf::Vector2f(offsetPositon.x + (x + 1) * tileSize.x, offsetPositon.y + y * tileSize.y); quad[2].position = sf::Vector2f(offsetPositon.x + (x + 1) * tileSize.x, offsetPositon.y + (y + 1) * tileSize.y); quad[3].position = sf::Vector2f(offsetPositon.x + x * tileSize.x, offsetPositon.y + (y + 1) * tileSize.y); // find out which type of tile to render, atm only air or stone TileStop *tilestop = mWorld->getTileStopAt(heightValue); sf::Vector2i texturePos = tilestop->getTexturePosition(); // define its 4 texture coordinates quad[0].texCoords = sf::Vector2f(texturePos.x, texturePos.y); quad[1].texCoords = sf::Vector2f(texturePos.x + 64, texturePos.y); quad[2].texCoords = sf::Vector2f(texturePos.x + 64, texturePos.y + 64); quad[3].texCoords = sf::Vector2f(texturePos.x, texturePos.y + 64); } } } All the code that uses libnoise in some way are World.cpp, World.h and Chunk.cpp, Chunk.h in the project.

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• JavaDay Taipei 2014 Trip Report

  - by reza_rahman

  JavaDay Taipei 2014 was held at the Taipei International Convention Center on August 1st. Organized by Oracle University, it is one of the largest Java developer events in Taiwan. This was another successful year for JavaDay Taipei with a fully sold out venue packed with youthful, energetic developers (this was my second time at the event and I have already been invited to speak again next year!). In addition to Oracle speakers like me, Steve Chin and Naveen Asrani, the event also featured a bevy of local speakers including Taipei Java community leaders. Topics included Java SE, Java EE, JavaFX, cloud and Big Data. It was my pleasure and privilege to present one of the opening keynotes for the event. I presented my session on Java EE titled "JavaEE.Next(): Java EE 7, 8, and Beyond". I covered the changes in Java EE 7 as well as what's coming in Java EE 8. I demoed the Cargo Tracker Java EE BluePrints. I also briefly talked about Adopt-a-JSR for Java EE 8. The slides for the keynote are below (click here to download and view the actual PDF): It appears your Web browser is not configured to display PDF files. No worries, just click here to download the PDF file. In the afternoon I did my JavaScript + Java EE 7 talk titled "Using JavaScript/HTML5 Rich Clients with Java EE 7". This talk is basically about aligning EE 7 with the emerging JavaScript ecosystem (specifically AngularJS). The talk was completely packed. The slide deck for the talk is here: JavaScript/HTML5 Rich Clients Using Java EE 7 from Reza Rahman The demo application code is posted on GitHub. The code should be a helpful resource if this development model is something that interests you. Do let me know if you need help with it but the instructions should be fairly self-explanatory. I am delivering this material at JavaOne 2014 as a two-hour tutorial. This should give me a little more bandwidth to dig a little deeper, especially on the JavaScript end. I finished off Java Day Taipei with my talk titled "Using NoSQL with ~JPA, EclipseLink and Java EE" (this was the last session of the conference). The talk covers an interesting gap that there is surprisingly little material on out there. The talk has three parts -- a birds-eye view of the NoSQL landscape, how to use NoSQL via a JPA centric facade using EclipseLink NoSQL, Hibernate OGM, DataNucleus, Kundera, Easy-Cassandra, etc and how to use NoSQL native APIs in Java EE via CDI. The slides for the talk are here: Using NoSQL with ~JPA, EclipseLink and Java EE from Reza Rahman The JPA based demo is available here, while the CDI based demo is available here. Both demos use MongoDB as the data store. Do let me know if you need help getting the demos up and running. After the event the Oracle University folks hosted a reception in the evening which was very well attended by organizers, speakers and local Java community leaders. I am extremely saddened by the fact that this otherwise excellent trip was scarred by terrible tragedy. After the conference I joined a few folks for a hike on the Maokong Mountain on Saturday. The group included friends in the Taiwanese Java community including Ian and Robbie Cheng. Without warning, fatal tragedy struck on a remote part of the trail. Despite best efforts by us, the excellent Taiwanese Emergency Rescue Team and World class Taiwanese physicians we were unable to save our friend Robbie Cheng's life. Robbie was just thirty-four years old and is survived by his younger brother, mother and father. Being the father of a young child myself, I can only imagine the deep sorrow that this senseless loss unleashes. Robbie was a key member of the Taiwanese Java community and a Java Evangelist at Sun at one point. Ironically the only picture I was able to take of the trail was mere moments before tragedy. I thought I should place him in that picture in profoundly respectful memoriam: Perhaps there is some solace in the fact that there is something inherently honorable in living a bright life, dying young and meeting one's end on a beautiful remote mountain trail few venture to behold let alone attempt to ascend in a long and tired lifetime. Perhaps I'd even say it's a fate I would not entirely regret facing if it were my own. With that thought in mind it seems appropriate to me to quote some lyrics from the song "Runes to My Memory" by legendary Swedish heavy metal band Amon Amarth idealizing a fallen Viking warrior cut down in his prime: "Here I lie on wet sand I will not make it home I clench my sword in my hand Say farewell to those I love When I am dead Lay me in a mound Place my weapons by my side For the journey to Hall up high When I am dead Lay me in a mound Raise a stone for all to see Runes carved to my memory" I submit my deepest condolences to Robbie's family and hope my next trip to Taiwan ends in a less somber note.

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• C: Running Unix configure file in Windows

  - by Shiftbit

  I would like to port a few applications that I use on Linux to Windows. In particular I have been working on wdiff. A program that compares the differences word by word of two files. Currently I have been able to successfully compile the program on windows through Cygwin. However, I would like to run the program natively on Windows similar to the Project: UnixUtils. How would I go about porting unix utilities on a windows environment? My possible guess it to manually create the ./configure file so that I can create a proper makefile. Am I on the right track? Has anyone had experience porting GNU software to windows? Update: I've compiled it on Code::Blocks and I get two errors: wdiff.c|226|error: `SIGPIPE' undeclared (first use in this function) readpipe.c:71: undefined reference to `_pipe' readpipe.c:74: undefined reference to `_fork This is a linux signal that is not supported by windows... equvilancy? wdiff.c|1198|error: `PRODUCT' undeclared (first use in this function)| this is in the configure.in file... hardcode would probably be the fastest solution... Outcome: MSYS took care of the configure problems, however MinGW couldnt solve the posix issues. I attempt to utilize pthreads as recommended by mrjoltcola. However, after several hours I couldnt get it to compile nor link using the provided libraries. I think if this had worked it would have been the solution I was after. Special mention to Michael Madsen for MSYS.

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• How can I effectively test against the Windows API?

  - by Billy ONeal

  I'm still having issues justifying TDD to myself. As I have mentioned in other questions, 90% of the code I write does absolutely nothing but Call some Windows API functions and Print out the data returned from said functions. The time spent coming up with the fake data that the code needs to process under TDD is incredible -- I literally spend 5 times as much time coming up with the example data as I would spend just writing application code. Part of this problem is that often I'm programming against APIs with which I have little experience, which forces me to write small applications that show me how the real API behaves so that I can write effective fakes/mocks on top of that API. Writing implementation first is the opposite of TDD, but in this case it is unavoidable: I do not know how the real API behaves, so how on earth am I going to be able to create a fake implementation of the API without playing with it? I have read several books on the subject, including Kent Beck's Test Driven Development, By Example, and Michael Feathers' Working Effectively with Legacy Code, which seem to be gospel for TDD fanatics. Feathers' book comes close in the way it describes breaking out dependencies, but even then, the examples provided have one thing in common: The program under test obtains input from other parts of the program under test. My programs do not follow that pattern. Instead, the only input to the program itself is the system upon which it runs. How can one effectively employ TDD on such a project?

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• ASP.Net MVC 3 Full Name In DropDownList

  - by tgriffiths

  I am getting a bit confused with this and need a little help please. I am developing a ASP.Net MVC 3 Web application using Entity Framework 4.1. I have a DropDownList on one of my Razor Views, and I wish to display a list of Full Names, for example Tom Jones Michael Jackson James Brown In my Controller I retrieve a List of User Objects, then select the FirstName and LastName of each User, and pass the data to a SelectList. List<User> Requesters = _userService.GetAllUsersByTypeIDOrgID(46, user.organisationID.Value).ToList(); var RequesterNames = from r in Requesters let person = new { UserID = r.userID, FullName = new { r.firstName, r.lastName } } orderby person.FullName ascending select person; viewModel.RequestersList = new SelectList(RequesterNames, "UserID", "FullName"); return View(viewModel); In my Razor View I have the following @Html.DropDownListFor(model => model.requesterID, Model.RequestersList, "Select", new { @class = "inpt_a"}) @Html.ValidationMessageFor(model => model.requesterID) However, when I run the code I get the following error At least one object must implement IComparable. I feel as if I am going about this the wrong way, so could someone please help with this? Thanks.

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• Really "wow" them in the interview

  - by Juliet

  Let me put it to you this way: I'm a top-notch programmer, but a notoriously bad interviewee. I've flunked 3 interviews consecutively because I get so nervous that my voice tightens at least 2 octaves higher and I start visibly shaking -- mind you, I can handle whatever technical questions the interviewer throws at me in that state, but I think it looks bad to come off as a quivering, squeaky-voiced young woman during a job interview. I've just got the personality type of a shy computer programmer. No matter how technical I am, I'm going to get passed up in favor of a smooth talker. I have another interview coming up shortly, and I want to really impress the company. Here are my trouble spots: What can I do to be less nervous during my interview? I always get really excited when I hear I have a face-to-face interview, but get more and more anxious as D-Day the interview approaches. My employers wants me to explain what I used to do at my prior employment. I'm a very chatty person and tend to talk/squeak for 10 minutes at a time. How long or short should I time my answers? On that note, when I'm explaining what I did at prior jobs, what exactly is my interviewer looking for? At some point, my interviewer will ask "do you have any questions for me while you're here?" I should, but what kinds of questions should I ask to show that I'm interested in being employed? My interviewer always asks why I'm looking for a new job. The real reason is that my present salary is $27K/yr [Edit to add: and I've yet to get a raise since I started], and I want to make more money -- otherwise the work environment is fine. How do I sugarcoat "I want to make more money" into something that sounds nicer? I have only one prior programmer job, and I've worked there for 18 months, but I have the skill of someone with 4 to 6 years of experience. What can I say to compete against applicants with more work experience? I took a low-paying $27K/yr programming job just to get my foot in IT, and I've been trying to leverage that job as a stepping stone to better opportunities. I get interviews because I consistently out-score senior-level developers in aptitude tests, and my desired salary range is right in the ballpark of what most companies want to offer. Unfortunately, while I've been a programming as a hobby for 10 years and I'm geared to graduate with my BA in Comp Sci in May '09, employers see me as a junior-level programmer with no degree. I want to prove them wrong and get a job that matches my skill level. I'd appreciate any advice anyone has to offer, especially if they can help me get a better job in the process.

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• Learning to create beautiful /next-generation GUI

  - by ShaChris23

  I really want to create a stunning-looking GUI desktop application that looks like, for example: Mac OS X interface Picasa desktop client on windows IPhone apps Office 2007 I've mostly been programming GUI using Qt/Swing/WinForm and I'm tired of creating so plain looking GUI, lol. So I was thinking about diving into stuff like: jQuery WPF/C# iPhone SDK Silverlight Adobe Air/Flex Just to get some ideas on how to create really cool looking UI. Does that sound like a good list? Any developers here that could share what platform they use to create very cool looking desktop app? On a sidenote, I really wonder what developers at Apple / Microsoft use to develop their own cool-looking software. EDIT A lot of responses talk about the importance of usability over "cool-looking".. I totally agree that usability and simplicity are the most important aspects of user interface design. I've been doing GUI development for a while now ( 3 years), so that I understand. But using cool-looking UI also improves user experience + it could make big difference on whether or not your software sells. I mean, otherwise why would Microsoft/Apple try to make their OS UI look "cooler" everytime there's a new version? Why would websites like pragprog.com, or versionsapp.com. make their websites look like that? Basically you kill 2 birds with one stone: stunnning-looking UI + super usability (because it looks simple and intuitive). That is what I'm striving for. And as far as I know, I cannot achieve that using Qt/Winform. Most of the books I have read just show you how to make average-looking (read: 1990's) UI. I want to learn how to create cool-looking UI. And the only place I see cool-looking UIs these days are the technology I list above. I'm not enamored with any technology; but I just want to know how things are done in other technology to see if I could apply them to the technology I'm using, or see if I could use those technology in my line of work. An example: if I were to pick between this UI and this UI, I probably would pick the latter, if just based on looks alone. Functionally, they are just the same UI; they both allow you to keep track of your time. They both contain buttons and textboxes, etc. But the fact that they look different, also differentiate them in terms of attractiveness. So in all, I think the "ice on the cake" is very important. I would say it's the thing you strive for after you are certain you have a totally intuitive, usable UI.

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• C# naming convention for enum and matching property

  - by Serge - appTranslator

  Hi All, I often find myself implementing a class maintaining some kind of own status property as an enum: I have a Status enum and ONE Status property of Status type. How should I solve this name conflict? public class Car { public enum Status { Off, Starting, Moving }; Status status = Status.Off; public Status Status // <===== Won't compile ===== { get { return status; } set { status = value; DoSomething(); } } } If the Status enum were common to different types, I'd put it outside the class and the problem would be solved. But Status applies to Car only hence it doesn't make sense to declare the enum outside the class. What naming convention do you use in this case? NB: This question was partially debated in comments of an answer of this question. Since it wasn't the main question, it didn't get much visibility. EDIT: Filip Ekberg suggests an IMO excellent workaround for the specific case of 'Status'. Yet I'd be interesting to read about solutions where the name of the enum/property is different, as in Michael Prewecki's answer. EDIT2 (May 2010): My favorite solution is to pluralize the enum type name, as suggested by Chris S. According to MS guidelines, this should be used for flag enums only. But I've come to like it more and more. I now use it for regular enums as well.

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• What would cause native gem extensions on OS X to build but fail to load?

  - by goodmike

  I am having trouble with some of my rubygems, in particular those that use native extensions. I am on a MacBookPro, with Snow Leopard. I have XCode 3.2.1 installed, with gcc 4.2.1. Ruby 1.8.6, because I'm lazy and a scaredy cat and don't want to upgrade yet. Ruby is running in 32-bit mode. I built this ruby from scratch when my MBP ran OSX 10.4. When I require one of the affected gems in irb, I get a Load Error for the gem extension's bundle file. For example, here's nokogigi dissing me: > require 'rubygems' = true > require 'nokogiri' LoadError: Failed to load /usr/local/lib/ruby/gems/1.8/gems/nokogiri-1.4.1/lib/nokogiri/nokogiri.bundle This is also happening with the Postgres pg and MongoDB mongo gems. My first thought was that the extensions must not be building right. But gem install wasn't throwing any errors. So I reinstalled with the verbose flag, hoping to see some helpful warnings. I've put the output in a Pastie, and the only warning I see is a consistent one about "passing argument n of ‘foo’ with different width due to prototype." I suspect that this might be an issue from upgrading to Snow Leopard, but I'm a little surprised to experience it now, since I've updated my XCode. Could it stem from running Ruby in 1.8.6? I'm embarrassed that I don't know quite enough about my Mac and OSX to know where to look next, so any guidance, even just a pointer to some document I couldn't find via Google, would be most welcome. Michael

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• Problem with type coercion and string concatenation in JavaScript in Greasemonkey script on Firefox

  - by Yi Jiang

  I'm creating a GreaseMonkey script to improve the user interface of the 10k tools Stack Overflow uses. I have encountered an unreproducible and frankly bizarre problem that has confounded me and the others in the JavaScript room on SO Chat. We have yet to find the cause after several lengthy debugging sessions. The problematic script can be found here. Source - Install The problem occurs at line 85, the line after the 'vodoo' comment: return (t + ' (' + +(+f.offensive + +f.spam) + ')'); It might look a little weird, but the + in front of the two variables and the inner bracket is for type coercion, the inner middle + is for addition, and the other ones are for concatenation. Nothing special, but observant reader might note that type coercion on the inner bracket is unnecessary, since both are already type coerced to numbers, and type coercing result is useless when they get concatenated into a string anyway. Not so! Removing the + breaks the script, causing f.offensive and f.spam to be concatenated instead of added together. Adding further console.log only makes things more confusing: console.log(f.offensive + f.spam); // 50 console.log('' + (+f.offensive + +f.spam)); // 5, but returning this yields 50 somehow console.log('' + (+f.offensive + +f.spam) + ''); // 50 Source: http://chat.stackoverflow.com/transcript/message/203261#203261 The problem is that this is unreproducible - running scripts like console.log('a' + (+'3' + +'1') + 'b'); in the Firebug console yields the correct result, as does (function(){ return 'a' + (+'3' + +'1') + 'b'; })(); Even pulling out large chunks of the code and running them in the console does not reproduce this bug: $('.post-menu a[id^=flag-post-]').each(function(){ var f = {offensive: '4', spam: '1'}; if(f){ $(this).text(function(i, t){ // Vodoo - please do not remove the '+' in front of the inner bracket return (t + ' (' + +(+f.offensive + +f.spam) + ')'); }); } }); Tim Stone in the chatroom has reproduction instruction for those who are below 10k. This bug only appears in Firefox - Chrome does not appear to exhibit this problem, leading me to believe that this may be a problem with either Firefox's JavaScript engine, or the Greasemonkey add-on. Am I right? I can be found in the JavaScript room if you want more detail and/or want to discuss this.

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• SQLite3 table not accepting INSERT INTO statements. The table is created, and so is the database, but nothing is passed into it

  - by user1460029

  <?php try { //open the database $db = new PDO('sqlite:music.db'); $db->exec("DELETE from Music;"); $db->exec("INSERT INTO Music(Title, Author, ReleaseDate) VALUES ('Whatd I Say', 'Ray Charles', '1956');" . "INSERT INTO Music(Title, Author, ReleaseDate) VALUES ('Smells Like Teen Spirit.', 'Nirvana', '1991');" . "INSERT INTO Music(Title, Author, ReleaseDate) VALUES ('Hey Jude', 'The Beatles', '1968');" . "INSERT INTO Music(Title, Author, ReleaseDate) VALUES ('Johnny B. Goode', 'Chuck Berry', '1958');" . "INSERT INTO Music(Title, Author, ReleaseDate) VALUES ('Good Vibrations', 'The Beach Boys', '1966');" . "INSERT INTO Music(Title, Author, ReleaseDate) VALUES ('Respect', 'Aretha Franklin', '1967');" . "INSERT INTO Music(Title, Author, ReleaseDate) VALUES ('Whats Going On', 'Marvin Gaye', '1971');" . "INSERT INTO Music(Title, Author, ReleaseDate) VALUES ('Imagine', 'John Lennon', '1971');" . "INSERT INTO Music(Title, Author, ReleaseDate) VALUES ('(I Cant Get No) Satisfaction', 'Rolling Stones', '1965');" . "INSERT INTO Music(Title, Author, ReleaseDate) VALUES ('Like A Rolling Stone', 'Bob Dylan', '1965');"); //now output the data to a simple html table... //example of specifier --> WHERE First=\'Josh\'; <-- print "<table border=1>"; print "<tr><td>Title</td><td>Author</td><td>Y.O.P.</td></tr>"; $result = $db->query('SELECT * FROM Music '); foreach($result as $row) { print "<td>".$row['Title']."</td>"; print "<td>".$row['Author']."</td>"; print "<td>".$row['ReleaseDate']."</td></tr>"; } print "</table>"; $db = NULL; } catch(PDOException $e) { print 'Exception : '.$e->getMessage(); } ?> I am not sure why nothing is being inserted into the table. The file 'music.db' exists in the right path. For the record, I can only use SQlite3, no SQL allowed. PHP is allowed, so is SQLite3.

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• Factory.next not working in FactoryGirl 4.x and Rails 3.0. Anyone know the replacement?

  - by cchapman900

  I'm very new to Rails and am following along in the Ruby on Rails 3 Tutorial book by Michael Hartl and am running into a little bump while using the factory_girl gem. Specifically, I'm not sure how to update the code Factory.next(...) Before coming to this, I did run into a little problem between the older version of FactoryGirl used in the book and the current 4.1 version I'm using now, but was able to resolve it. Specifically, the old way of writing code as user = Factory(:user) needed to be updated to user = FactoryGirl.create(:user) That was fine, but now I'm coming to the code (as written in the book): spec/controllers/users_controler_spec.rb . @users << Factory(:user, :email => Factory.next(:email)) . which I've tried updating to . @users << FactoryGirl.create(:user, :email => FactoryGirl.next(:email)) . but get the error: Failure/Error: @users << FactoryGirl.create(:user, :email => FactoryGirl.next(:email)) NoMethodError: undefined method `next' for FactoryGirl:Module I've tried a few different variations but still can't quite get it. Is the problem I'm having with FactoryGirl and just not using the gem correctly or does it have something to do with the Ruby methods?

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• Intellisense for custom config section problem with namespaces

  - by Quick Joe Smith

  I have just rolled a custom configuration section, created an accompanying schema document for Intellisense and added it to the Web.config's Schemas property as per Michael Stum's answer to another similar question. Unfortunately, and possibly due to me creating the XSD by hand with limited knowledge, the Intellisense relies on an xmlns attribute pointing to my XSD file's namespace being present in the custom config element. However, when running the project I get an Unrecognized attribute 'xmlns'. Note that attribute names are case-sensitive error. I could probably just modify my XSD file to define the xmlns attribute for that element, however I am wondering if this is just a bandaid fix to a larger problem. I must confess I don't have a very good understanding of XML namespaces so this might be an oppportunity to set me straight on a few things. Here is the attributes for my XSD file's root xs:schema element: <xs:schema id="awesomeConfig" targetNamespace="http://awesome.com/schemas" xmlns="http://awesome.com/schemas" elementFormDefault="qualified" xmlns:xs="http://www.w3.org/2001/XMLSchema"> ... </xs:schema> And on creating the element in the Web.config file, Visual Studio 2008 automatically appends: <awesomeConfig xmlns="http://awesome.com/schemas"></awesomeConfig> So have I misunderstood the meaning of the xs:schema attributes at all, or is the proper solution as simple as it seems?

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• Adding a Taxonomy Filter to a Custom Post Type

  - by ken

  There is an amazing conversation from about two years ago on the Wordpress Answer site where a number of people came up with good solutions for adding a taxonomy filter to the admin screen for your custom post types (see URL for screen I'm referring to): http://[yoursite.com]/wp-admin/edit.php?s&post_status=all&post_type=[post-type] Anyway, I loved Michael's awesome contribution but in the end used Somatic's implementation with the hierarchy option from Manny. I wrapped it in a class - cuz that's how I like to do things -- and it ALMOST works. The dropdown appears but the values in the dropdown are all looking in the $_GET property for the taxonomies slug-name that you are filtering by. For some reason I don't get anything. I looked at the HTML of the dropdown and it appears ok to me. Here's a quick screen shot for some context: You can tell from this that my post-type is called "exercise" and that the Taxonomy I'm trying to use as a filter is "actions". Here then is the HTML surrounding the dropdown list: <select name="actions" id="actions" class="postform"> <option value="">Show all Actions</option> <option value="ate-dinner">Ate dinner(1)</option> <option value="went-running">Went running(1)</option> </select> I have also confirmed that all of the form elements are within the part of the DOM. And yet if I choose "Went running" and click on the filter button the URL query string comes back without ANY reference to what i've picked. More explicitly, the page first loads with the following URL: /wp-admin/edit.php?post_type=exercise and after pressing the filter button while having picked "Went Running" as an option from the actions filter: /wp-admin/edit.php?s&post_status=all&post_type=exercise&action=-1&m=0&actions&paged=1&mode=list&action2=-1 actually you can see a reference to an "actions" variable but it's set to nothing and as I now look in detail it appears that the moment I hit "filter" on the page it resets the filter dropdown to the default "Show All Actions". Can anyone help me with this?

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• Spring MVC + Hibernate encoding problem

  - by Bar

  I work on Spring MVC + Hibernate application, use MySQL (ver. 5.0.51a) with the InnoDB engine. The problem appears when I am sending a form with cyrillic characters. As the result, database contains senseless chars in unknown encoding. All the JSP pages, database (+ tables and fields) created using UTF-8. Hibernate config also contains property which sets encoding to UTF-8. I had solved this by creating filter which encodes request content with UTF-8. Exemplary code: … encoding = "UTF-8"; request.setCharacterEncoding(encoding); chain.doFilter(request, response); … But it visibly slows down the app. The interesting thing is that executing insert query directly from the app (i.e. running from Eclipse as Java Application) works perfect. Any suggestions are welcome. TIA, Michael.

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• JavaFx 2.1, 2.2 TableView update issue

  - by Lewis Liu

  My application uses JPA read data into TableView then modify and display them. The table refreshed modified record under JavaFx 2.0.3. Under JavaFx 2.1, 2.2, the table wouldn't refresh the update anymore. I found other people have similar issue. My plan was to continue using 2.0.3 until someone fixes the issue under 2.1 and 2.2. Now I know it is not a bug and wouldn't be fixed. Well, I don't know how to deal with this. Following are codes are modified from sample demo to show the issue. If I add a new record or delete a old record from table, table refreshes fine. If I modify a record, the table wouldn't refreshes the change until a add, delete or sort action is taken. If I remove the modified record and add it again, table refreshes. But the modified record is put at button of table. Well, if I remove the modified record, add the same record then move the record to the original spot, the table wouldn't refresh anymore. Below is a completely code, please shine some light on this. import javafx.application.Application; import javafx.beans.property.SimpleStringProperty; import javafx.collections.FXCollections; import javafx.collections.ObservableList; import javafx.event.ActionEvent; import javafx.event.EventHandler; import javafx.geometry.HPos; import javafx.geometry.Insets; import javafx.geometry.Pos; import javafx.scene.Group; import javafx.scene.Scene; import javafx.scene.control.*; import javafx.scene.control.cell.PropertyValueFactory; import javafx.scene.layout.GridPane; import javafx.scene.layout.HBox; import javafx.scene.layout.VBox; import javafx.scene.text.Font; import javafx.stage.Modality; import javafx.stage.Stage; import javafx.stage.StageStyle; public class Main extends Application { private TextField firtNameField = new TextField(); private TextField lastNameField = new TextField(); private TextField emailField = new TextField(); private Stage editView; private Person fPerson; public static class Person { private final SimpleStringProperty firstName; private final SimpleStringProperty lastName; private final SimpleStringProperty email; private Person(String fName, String lName, String email) { this.firstName = new SimpleStringProperty(fName); this.lastName = new SimpleStringProperty(lName); this.email = new SimpleStringProperty(email); } public String getFirstName() { return firstName.get(); } public void setFirstName(String fName) { firstName.set(fName); } public String getLastName() { return lastName.get(); } public void setLastName(String fName) { lastName.set(fName); } public String getEmail() { return email.get(); } public void setEmail(String fName) { email.set(fName); } } private TableView<Person> table = new TableView<Person>(); private final ObservableList<Person> data = FXCollections.observableArrayList( new Person("Jacob", "Smith", "[email protected]"), new Person("Isabella", "Johnson", "[email protected]"), new Person("Ethan", "Williams", "[email protected]"), new Person("Emma", "Jones", "[email protected]"), new Person("Michael", "Brown", "michael[email protected]")); public static void main(String[] args) { launch(args); } @Override public void start(Stage stage) { Scene scene = new Scene(new Group()); stage.setTitle("Table View Sample"); stage.setWidth(535); stage.setHeight(535); editView = new Stage(); final Label label = new Label("Address Book"); label.setFont(new Font("Arial", 20)); TableColumn firstNameCol = new TableColumn("First Name"); firstNameCol.setCellValueFactory( new PropertyValueFactory<Person, String>("firstName")); firstNameCol.setMinWidth(150); TableColumn lastNameCol = new TableColumn("Last Name"); lastNameCol.setCellValueFactory( new PropertyValueFactory<Person, String>("lastName")); lastNameCol.setMinWidth(150); TableColumn emailCol = new TableColumn("Email"); emailCol.setMinWidth(200); emailCol.setCellValueFactory( new PropertyValueFactory<Person, String>("email")); table.setItems(data); table.getColumns().addAll(firstNameCol, lastNameCol, emailCol); //--- create a edit button and a editPane to edit person Button addButton = new Button("Add"); addButton.setOnAction(new EventHandler<ActionEvent>() { @Override public void handle(ActionEvent event) { fPerson = null; firtNameField.setText(""); lastNameField.setText(""); emailField.setText(""); editView.show(); } }); Button editButton = new Button("Edit"); editButton.setOnAction(new EventHandler<ActionEvent>() { @Override public void handle(ActionEvent event) { if (table.getSelectionModel().getSelectedItem() != null) { fPerson = table.getSelectionModel().getSelectedItem(); firtNameField.setText(fPerson.getFirstName()); lastNameField.setText(fPerson.getLastName()); emailField.setText(fPerson.getEmail()); editView.show(); } } }); Button deleteButton = new Button("Delete"); deleteButton.setOnAction(new EventHandler<ActionEvent>() { @Override public void handle(ActionEvent event) { if (table.getSelectionModel().getSelectedItem() != null) { data.remove(table.getSelectionModel().getSelectedItem()); } } }); HBox addEditDeleteButtonBox = new HBox(); addEditDeleteButtonBox.getChildren().addAll(addButton, editButton, deleteButton); addEditDeleteButtonBox.setAlignment(Pos.CENTER_RIGHT); addEditDeleteButtonBox.setSpacing(3); GridPane editPane = new GridPane(); editPane.getStyleClass().add("editView"); editPane.setPadding(new Insets(3)); editPane.setHgap(5); editPane.setVgap(5); Label personLbl = new Label("Person:"); editPane.add(personLbl, 0, 1); GridPane.setHalignment(personLbl, HPos.LEFT); firtNameField.setPrefWidth(250); lastNameField.setPrefWidth(250); emailField.setPrefWidth(250); Label firstNameLabel = new Label("First Name:"); Label lastNameLabel = new Label("Last Name:"); Label emailLabel = new Label("Email:"); editPane.add(firstNameLabel, 0, 3); editPane.add(firtNameField, 1, 3); editPane.add(lastNameLabel, 0, 4); editPane.add(lastNameField, 1, 4); editPane.add(emailLabel, 0, 5); editPane.add(emailField, 1, 5); GridPane.setHalignment(firstNameLabel, HPos.RIGHT); GridPane.setHalignment(lastNameLabel, HPos.RIGHT); GridPane.setHalignment(emailLabel, HPos.RIGHT); Button saveButton = new Button("Save"); saveButton.setOnAction(new EventHandler<ActionEvent>() { @Override public void handle(ActionEvent event) { if (fPerson == null) { fPerson = new Person( firtNameField.getText(), lastNameField.getText(), emailField.getText()); data.add(fPerson); } else { int k = -1; if (data.size() > 0) { for (int i = 0; i < data.size(); i++) { if (data.get(i) == fPerson) { k = i; } } } fPerson.setFirstName(firtNameField.getText()); fPerson.setLastName(lastNameField.getText()); fPerson.setEmail(emailField.getText()); data.set(k, fPerson); table.setItems(data); // The following will work, but edited person has to be added to the button // // data.remove(fPerson); // data.add(fPerson); // add and remove refresh the table, but now move edited person to original spot, // it failed again with the following code // while (data.indexOf(fPerson) != k) { // int i = data.indexOf(fPerson); // Collections.swap(data, i, i - 1); // } } editView.close(); } }); Button cancelButton = new Button("Cancel"); cancelButton.setOnAction(new EventHandler<ActionEvent>() { @Override public void handle(ActionEvent event) { editView.close(); } }); HBox saveCancelButtonBox = new HBox(); saveCancelButtonBox.getChildren().addAll(saveButton, cancelButton); saveCancelButtonBox.setAlignment(Pos.CENTER_RIGHT); saveCancelButtonBox.setSpacing(3); VBox editBox = new VBox(); editBox.getChildren().addAll(editPane, saveCancelButtonBox); Scene editScene = new Scene(editBox); editView.setTitle("Person"); editView.initStyle(StageStyle.UTILITY); editView.initModality(Modality.APPLICATION_MODAL); editView.setScene(editScene); editView.close(); final VBox vbox = new VBox(); vbox.setSpacing(5); vbox.getChildren().addAll(label, table, addEditDeleteButtonBox); vbox.setPadding(new Insets(10, 0, 0, 10)); ((Group) scene.getRoot()).getChildren().addAll(vbox); stage.setScene(scene); stage.show(); } }

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• Save XML directly to Database with C#

  - by LifeH2O

  Here is a part of my xml file <teams> <team-profile> <name>Australia</name> <id>1</id> <stats type="Test"> <span>1877-2010</span> <matches>721</matches> <won>339</won> <lost>186</lost> <tied>2</tied> <draw>194</draw> <percentage>47.01</percentage> </stats> <squad> <player id="135" fullname="Shane Warne"/> <player id="136" fullname="Damien Martyn"/> <player id="138" fullname="Michael Clarke"/> </squad> </team-profile> </team> I have read somewhere that there is a way to save this XML directly to database. I am using VS2010. I have created the dataset, for the data i need from this xml. Is there any way to map this XML directly on dataset? Any other idea? I also have to save some other more complex XML files to database. I have tried xsd.exe to create xsd schema for this XML.

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• Am I mocking this helper function right in my Django test?

  - by CppLearner

  lib.py from django.core.urlresolvers import reverse def render_reverse(f, kwargs): """ kwargs is a dictionary, usually of the form {'args': [cbid]} """ return reverse(f, **kwargs) tests.py from lib import render_reverse, print_ls class LibTest(unittest.TestCase): def test_render_reverse_is_correct(self): #with patch('webclient.apps.codebundles.lib.reverse') as mock_reverse: with patch('django.core.urlresolvers.reverse') as mock_reverse: from lib import render_reverse mock_f = MagicMock(name='f', return_value='dummy_views') mock_kwargs = MagicMock(name='kwargs',return_value={'args':['123']}) mock_reverse.return_value = '/natrium/cb/details/123' response = render_reverse(mock_f(), mock_kwargs()) self.assertTrue('/natrium/cb/details/' in response) But instead, I get File "/var/lib/graphyte-webclient/graphyte-webenv/lib/python2.6/site-packages/django/core/urlresolvers.py", line 296, in reverse "arguments '%s' not found." % (lookup_view_s, args, kwargs)) NoReverseMatch: Reverse for 'dummy_readfile' with arguments '('123',)' and keyword arguments '{}' not found. Why is it calling reverse instead of my mock_reverse (it is looking up my urls.py!!) The author of Mock library Michael Foord did a video cast here (around 9:17), and in the example he passed the mock object request to the view function index. Furthermore, he patched POll and assigned an expected return value. Isn't that what I am doing here? I patched reverse? Thanks.

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• Xcode "Build and Archive" from command line

  - by Dan Fabulich

  Xcode 3.2 provides an awesome new feature under the Build menu, "Build and Archive" which generates an .ipa file suitable for Ad Hoc distribution. You can also open the Organizer, go to "Archived Applications," and "Submit Application to iTunesConnect." Is there a way to use "Build and Archive" from the command line (as part of a build script)? I'd assume that xcodebuild would be involved somehow, but the man page doesn't seem to say anything about this. UPDATE Michael Grinich requested clarification; here's what exactly you can't do with command-line builds, features you can ONLY do with Xcode's Organizer after you "Build and Archive." You can click "Share Application..." to share your IPA with beta testers. As Guillaume points out below, due to some Xcode magic, this IPA file does not require a separately distributed .mobileprovision file that beta testers need to install; that's magical. No command-line script can do it. For example, Arrix's script (submitted May 1) does not meet that requirement. More importantly, after you've beta tested a build, you can click "Submit Application to iTunes Connect" to submit that EXACT same build to Apple, the very binary you tested, without rebuilding it. That's impossible from the command line, because signing the app is part of the build process; you can sign bits for Ad Hoc beta testing OR you can sign them for submission to the App Store, but not both. No IPA built on the command-line can be beta tested on phones and then submitted directly to Apple. I'd love for someone to come along and prove me wrong: both of these features work great in the Xcode GUI and cannot be replicated from the command line.

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