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• Community Branching

  - by Dane Morgridge

  As some may have noticed, I have taken a liking to Ruby (and Rails in particular) quite a bit recently. This last weekend I spoke at the NYC Code Camp on a comparison of ASP.NET and Rails as well as an intro to Entity Framework talk.  I am speaking at RubyNation in April and have submitted to other ruby conferences around the area and I am also doing a Rails and MongoDB talk at the Philly Code Camp in April. Before you start to think this is my "I'm leaving .NET post", which it isn't so I need to clarify. I am not, nor do I intend to any time in the near future plan on abandoning .NET.  I am simply branching out into another community based on a development technology that I very much enjoy.  If you look at my twitter bio, you will see that I am into Entity Framework, Ruby on Rails, C++ and ASP.NET MVC, and not necessarily in that order.  I know you're probably thinking to your self that I am crazy, which is probably true on several levels (especially the C++ part). I was actually crazy enough at the NYC Code Camp to show up wearing a Linux t-shirt, presenting with my MacBook Pro on Entity Framework, ASP.NET MVC and Rails. (I did get pelted in the head with candy by Rachel Appel for it though) At all of the code camps I am submitting to this year, i will be submitting sessions on likely all four topics, and some sessions will be a combination of 2 or more.  For example, my "ASP.NET MVC: A Gateway To Rails?" talk touches ASP.NET MVC, Entity Framework Code First and Rails. Simply put (and I talk about this in my MVC & Rails talk) is that learning and using Rails has made me a better ASP.NET MVC developer. Just one example of this is helper methods.  When I started working with ASP.NET MVC, I didn't really want to use helpers and preferred to just use standard html tags, especially where links were concerned.  It was just me being stubborn and not really seeing all of the benefit of the helpers.  To my defense, coming from WebForms, I wanted to be as bare metal as possible and it seemed at first like a lot of the helpers were an unnecessary abstraction. I took my first look at Rails back in v1 and didn't spend very much time with it so I dismissed it and went on my merry ASP.NET WebForms way.  Then I picked up ASP.NET MVC and grasped the MVC pattern itself much better. After this, I took another look at Rails and everything made sense.  I decided then to learn Rails. (I think it is important for developers to learn new languages and platforms regularly so it was a natural progression for me) I wanted to learn it the right way, so when I dug into code, everyone used helpers everywhere for pretty much everything possible. I took some time to dig in and found out how helpful they were and subsequently realized how awesome they were in ASP.NET MVC also and started using them. In short, I love Rails (and Ruby in general).  I also love ASP.NET MVC and Entity Framework and yes I still love C++.  I have varying degrees of love for them individually at any given moment and it is likely to shift based on the current project I am working on.  I know you're thinking it so before you ask the question. "Which do I use when?", I'm going to give the standard developer answer of: It depends.  There are a lot of factors that I am not going to even go into that would go into a decision.  The most basic question I would ask though is,  does this project depend on .NET?  If it does, then I'd say that ASP.NET MVC is probably going to be the more logical choice and I am going to leave it at that.  I am working on projects right now in both technologies and I don't see that changing anytime soon (one project even uses both). With all that being said, you'll find me at code camps, conferences and user groups presenting on .NET, Ruby or both, writing about .NET and Ruby and I will likely be blogging on both in the future.  I know of others that have successfully branched out to other communities and with any luck I'll be successful at it too. On a (sorta) side note, I read a post by Justin Etheredge the other day that pretty much sums up my feelings about Ruby as a language.  I highly recommend checking it out: What Is So Great About Ruby?

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• Anatomy of a .NET Assembly - CLR metadata 2

  - by Simon Cooper

  Before we look any further at the CLR metadata, we need a quick diversion to understand how the metadata is actually stored. Encoding table information As an example, we'll have a look at a row in the TypeDef table. According to the spec, each TypeDef consists of the following: Flags specifying various properties of the class, including visibility. The name of the type. The namespace of the type. What type this type extends. The field list of this type. The method list of this type. How is all this data actually represented? Offset & RID encoding Most assemblies don't need to use a 4 byte value to specify heap offsets and RIDs everywhere, however we can't hard-code every offset and RID to be 2 bytes long as there could conceivably be more than 65535 items in a heap or more than 65535 fields or types defined in an assembly. So heap offsets and RIDs are only represented in the full 4 bytes if it is required; in the header information at the top of the #~ stream are 3 bits indicating if the #Strings, #GUID, or #Blob heaps use 2 or 4 bytes (the #US stream is not accessed from metadata), and the rowcount of each table. If the rowcount for a particular table is greater than 65535 then all RIDs referencing that table throughout the metadata use 4 bytes, else only 2 bytes are used. Coded tokens Not every field in a table row references a single predefined table. For example, in the TypeDef extends field, a type can extend another TypeDef (a type in the same assembly), a TypeRef (a type in a different assembly), or a TypeSpec (an instantiation of a generic type). A token would have to be used to let us specify the table along with the RID. Tokens are always 4 bytes long; again, this is rather wasteful of space. Cutting the RID down to 2 bytes would make each token 3 bytes long, which isn't really an optimum size for computers to read from memory or disk. However, every use of a token in the metadata tables can only point to a limited subset of the metadata tables. For the extends field, we only need to be able to specify one of 3 tables, which we can do using 2 bits: 0x0: TypeDef 0x1: TypeRef 0x2: TypeSpec We could therefore compress the 4-byte token that would otherwise be needed into a coded token of type TypeDefOrRef. For each type of coded token, the least significant bits encode the table the token points to, and the rest of the bits encode the RID within that table. We can work out whether each type of coded token needs 2 or 4 bytes to represent it by working out whether the maximum RID of every table that the coded token type can point to will fit in the space available. The space available for the RID depends on the type of coded token; a TypeOrMethodDef coded token only needs 1 bit to specify the table, leaving 15 bits available for the RID before a 4-byte representation is needed, whereas a HasCustomAttribute coded token can point to one of 18 different tables, and so needs 5 bits to specify the table, only leaving 11 bits for the RID before 4 bytes are needed to represent that coded token type. For example, a 2-byte TypeDefOrRef coded token with the value 0x0321 has the following bit pattern: 0 3 2 1 0000 0011 0010 0001 The first two bits specify the table - TypeRef; the other bits specify the RID. Because we've used the first two bits, we've got to shift everything along two bits: 000000 1100 1000 This gives us a RID of 0xc8. If any one of the TypeDef, TypeRef or TypeSpec tables had more than 16383 rows (2^14 - 1), then 4 bytes would need to be used to represent all TypeDefOrRef coded tokens throughout the metadata tables. Lists The third representation we need to consider is 1-to-many references; each TypeDef refers to a list of FieldDef and MethodDef belonging to that type. If we were to specify every FieldDef and MethodDef individually then each TypeDef would be very large and a variable size, which isn't ideal. There is a way of specifying a list of references without explicitly specifying every item; if we order the MethodDef and FieldDef tables by the owning type, then the field list and method list in a TypeDef only have to be a single RID pointing at the first FieldDef or MethodDef belonging to that type; the end of the list can be inferred by the field list and method list RIDs of the next row in the TypeDef table. Going back to the TypeDef If we have a look back at the definition of a TypeDef, we end up with the following reprensentation for each row: Flags - always 4 bytes Name - a #Strings heap offset. Namespace - a #Strings heap offset. Extends - a TypeDefOrRef coded token. FieldList - a single RID to the FieldDef table. MethodList - a single RID to the MethodDef table. So, depending on the number of entries in the heaps and tables within the assembly, the rows in the TypeDef table can be as small as 14 bytes, or as large as 24 bytes. Now we've had a look at how information is encoded within the metadata tables, in the next post we can see how they are arranged on disk.

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• Computer Networks UNISA - Chap 15 &ndash; Network Management

  - by MarkPearl

  After reading this section you should be able to Understand network management and the importance of documentation, baseline measurements, policies, and regulations to assess and maintain a network’s health. Manage a network’s performance using SNMP-based network management software, system and event logs, and traffic-shaping techniques Identify the reasons for and elements of an asset managements system Plan and follow regular hardware and software maintenance routines Fundamentals of Network Management Network management refers to the assessment, monitoring, and maintenance of all aspects of a network including checking for hardware faults, ensuring high QoS, maintaining records of network assets, etc. Scope of network management differs depending on the size and requirements of the network. All sub topics of network management share the goals of enhancing the efficiency and performance while preventing costly downtime or loss. Documentation The way documentation is stored may vary, but to adequately manage a network one should at least record the following… Physical topology (types of LAN and WAN topologies – ring, star, hybrid) Access method (does it use Ethernet 802.3, token ring, etc.) Protocols Devices (Switches, routers, etc) Operating Systems Applications Configurations (What version of operating system and config files for serve / client software) Baseline Measurements A baseline is a report of the network’s current state of operation. Baseline measurements might include the utilization rate for your network backbone, number of users logged on per day, etc. Baseline measurements allow you to compare future performance increases or decreases caused by network changes or events with past network performance. Obtaining baseline measurements is the only way to know for certain whether a pattern of usage has changed, or whether a network upgrade has made a difference. There are various tools available for measuring baseline performance on a network. Policies, Procedures, and Regulations Following rules helps limit chaos, confusion, and possibly downtime. The following policies and procedures and regulations make for sound network management. Media installations and management (includes designing physical layout of cable, etc.) Network addressing policies (includes choosing and applying a an addressing scheme) Resource sharing and naming conventions (includes rules for logon ID’s) Security related policies Troubleshooting procedures Backup and disaster recovery procedures In addition to internal policies, a network manager must consider external regulatory rules. Fault and Performance Management After documenting every aspect of your network and following policies and best practices, you are ready to asses you networks status on an on going basis. This process includes both performance management and fault management. Network Management Software To accomplish both fault and performance management, organizations often use enterprise-wide network management software. There various software packages that do this, each collect data from multiple networked devices at regular intervals, in a process called polling. Each managed device runs a network management agent. So as not to affect the performance of a device while collecting information, agents do not demand significant processing resources. The definition of a managed devices and their data are collected in a MIB (Management Information Base). Agents communicate information about managed devices via any of several application layer protocols. On modern networks most agents use SNMP which is part of the TCP/IP suite and typically runs over UDP on port 161. Because of the flexibility and sophisticated network management applications are a challenge to configure and fine-tune. One needs to be careful to only collect relevant information and not cause performance issues (i.e. pinging a device every 5 seconds can be a problem with thousands of devices). MRTG (Multi Router Traffic Grapher) is a simple command line utility that uses SNMP to poll devices and collects data in a log file. MRTG can be used with Windows, UNIX and Linux. System and Event Logs Virtually every condition recognized by an operating system can be recorded. This is typically done using event logs. In Windows there is a GUI event log viewer. Similar information is recorded in UNIX and Linux in a system log. Much of the information collected in event logs and syslog files does not point to a problem, even if it is marked with a warning so it is important to filter your logs appropriately to reduce the noise. Traffic Shaping When a network must handle high volumes of network traffic, users benefit from performance management technique called traffic shaping. Traffic shaping involves manipulating certain characteristics of packets, data streams, or connections to manage the type and amount of traffic traversing a network or interface at any moment. Its goals are to assure timely delivery of the most important traffic while offering the best possible performance for all users. Several types of traffic prioritization exist including prioritizing traffic according to any of the following characteristics… Protocol IP address User group DiffServr VLAN tag in a Data Link layer frame Service or application Caching In addition to traffic shaping, a network or host might use caching to improve performance. Caching is the local storage of frequently needed files that would otherwise be obtained from an external source. By keeping files close to the requester, caching allows the user to access those files quickly. The most common type of caching is Web caching, in which Web pages are stored locally. To an ISP, caching is much more than just convenience. It prevents a significant volume of WAN traffic, thus improving performance and saving money. Asset Management Another key component in managing networks is identifying and tracking its hardware. This is called asset management. The first step to asset management is to take an inventory of each node on the network. You will also want to keep records of every piece of software purchased by your organization. Asset management simplifies maintaining and upgrading the network chiefly because you know what the system includes. In addition, asset management provides network administrators with information about the costs and benefits of certain types of hardware or software. Change Management Networks are always in a stage of flux with various aspects including… Software changes and patches Client Upgrades Shared Application Upgrades NOS Upgrades Hardware and Physical Plant Changes Cabling Upgrades Backbone Upgrades For a detailed explanation on each of these read the textbook (Page 750 – 761)

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• Implement Tree/Details With Taskflow Regions Using EJB

  - by Deepak Siddappa

  This article describes on Display Tree/Details using taskflow regions.Use Case DescriptionLet us take scenario where we need to display Tree/Details, left region contains category hierarchy with items listed in a tree structure (ex:- Region-Countries-Locations-Departments in tree format) and right region contains the Employees list.In detail, Here User may drills down through categories using a tree until Employees are listed. Clicking the tree node name displays Employee list in the adjacent pane related to particular tree node. Implementation StepsThe script for creating the tables and inserting the data required for this application CreateSchema.sql Lets create a Java EE Web Application with Entities based on Regions, Countries, Locations, Departments and Employees table. Create a Stateless Session Bean and data control for the Stateless Session Bean. Add the below code to the session bean and expose the method in local/remote interface and generate a data control for that.Note:- Here in the below code "em" is a EntityManager. public List<Employees> empFilteredByTreeNode(String treeNodeType, String paramValue) { String queryString = null; try { if (treeNodeType == "null") { queryString = "select * from Employees emp ORDER BY emp.employee_id ASC"; } else if (Pattern.matches("[a-zA-Z]+[_]+[a-zA-Z]+[_]+[[0-9]+]+", treeNodeType)) { queryString = "select * from employees emp INNER JOIN departments dept\n" + "ON emp.department_id = dept.department_id JOIN locations loc\n" + "ON dept.location_id = loc.location_id JOIN countries cont\n" + "ON loc.country_id = cont.country_id JOIN regions reg\n" + "ON cont.region_id = reg.region_id and reg.region_name = '" + paramValue + "' ORDER BY emp.employee_id ASC"; } else if (treeNodeType.contains("regionsFindAll_bc_countriesList_1")) { queryString = "select * from employees emp INNER JOIN departments dept \n" + "ON emp.department_id = dept.department_id JOIN locations loc \n" + "ON dept.location_id = loc.location_id JOIN countries cont \n" + "ON loc.country_id = cont.country_id and cont.country_name = '" + paramValue + "' ORDER BY emp.employee_id ASC"; } else if (treeNodeType.contains("regionsFindAll_bc_locationsList_1")) { queryString = "select * from employees emp INNER JOIN departments dept ON emp.department_id = dept.department_id JOIN locations loc ON dept.location_id = loc.location_id and loc.city = '" + paramValue + "' ORDER BY emp.employee_id ASC"; } else if (treeNodeType.trim().contains("regionsFindAll_bc_departmentsList_1")) { queryString = "select * from Employees emp INNER JOIN Departments dept ON emp.DEPARTMENT_ID = dept.DEPARTMENT_ID and dept.DEPARTMENT_NAME = '" + paramValue + "'"; } } catch (NullPointerException e) { System.out.println(e.getMessage()); } return em.createNativeQuery(queryString, Employees.class).getResultList(); } In the ViewController project, create two ADF taskflow with page Fragments and name them as FirstTaskflow and SecondTaskflow respectively. Open FirstTaskflow,from component palette drop view(Page Fragment) name it as TreeList.jsff. Open SeconfTaskflow, from component palette drop view(Page Fragment) name it as EmpList.jsff and create two paramters in its overview parameters tab as shown in below image. Open TreeList.jsff , from data control palette drop regionsFindAll->Tree as ADF Tree. In Edit Tree Binding dialog, for Tree Level Rules select the display attributes as follows:-model.Regions - regionNamemodel.Countries - countryNamemodel.Locations - citymodel.Departments - departmentName In structure panel, click on af:Tree - t1 and select selectionListener with edit property. Create a "TreeBean" managed bean with scope as "session" as shown in below Image. Create new method as getTreeNodeSelectedValue and click ok. Open TreeBean managed bean and add the below code: private String treeNodeType; private String paramValue; public void getTreeNodeSelectedValue(SelectionEvent selectionEvent) { RichTree tree = (RichTree)selectionEvent.getSource(); RowKeySet addedSet = selectionEvent.getAddedSet(); Iterator i = addedSet.iterator(); TreeModel model = (TreeModel)tree.getValue(); model.setRowKey(i.next()); JUCtrlHierNodeBinding node = (JUCtrlHierNodeBinding)tree.getRowData(); //oracle.jbo.Row Row rw = node.getRow(); Object selectedTreeNode = node.getAttribute(0); Object treeListType = node.getBindings(); String treeNodeType = treeListType.toString(); this.setParamValue(selectedTreeNode.toString()); this.setTreeNodeType(treeNodeType); } public void setTreeNodeType(String treeNodeType) { this.treeNodeType = treeNodeType; } public String getTreeNodeType() { return treeNodeType; } public void setParamValue(String paramValue) { this.paramValue = paramValue; } public String getParamValue() { return paramValue; }<br /> Open EmpList.jsff , from data control palette drop empFilteredByTreeNode->Employees->Table as ADF Read-only Table. After selecting the  Employees result set, in Edit Action Binding dialog window pass the pageFlowScope parameters as shown in below Image. In empList.jsff page, click Binding tab and click on Create Executable binding and select Invoke action and follow as shown in below image. Edit executeEmpFiltered invoke action properties and set the Refresh to ifNeeded, So when ever the page needs the method will be executed. Create Main.jspx page with page template as Oracle Three Column Layout. Drop FirstTaskflow as Region in start facet and drop SecondTaskflow as Region in center facet, Edit task Flow Binding dialog window pass the Input Paramters as shown in below Image. Run the Main.jspx, tree will be displayed in left region and emp details will displyaed on the right region. Click on the Americas in tree node, all emp related to the Americas related will be displayed. Click on Americas->United States of America->South San Francisco->Accounting, only employee belongs to the Accounting department will be displayed.

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• ROracle support for TimesTen In-Memory Database

  - by Sam Drake

  Today's guest post comes from Jason Feldhaus, a Consulting Member of Technical Staff in the TimesTen Database organization at Oracle.  He shares with us a sample session using ROracle with the TimesTen In-Memory database.  Beginning in version 1.1-4, ROracle includes support for the Oracle Times Ten In-Memory Database, version 11.2.2. TimesTen is a relational database providing very fast and high throughput through its memory-centric architecture.  TimesTen is designed for low latency, high-volume data, and event and transaction management. A TimesTen database resides entirely in memory, so no disk I/O is required for transactions and query operations. TimesTen is used in applications requiring very fast and predictable response time, such as real-time financial services trading applications and large web applications. TimesTen can be used as the database of record or as a relational cache database to Oracle Database. ROracle provides an interface between R and the database, providing the rich functionality of the R statistical programming environment using the SQL query language. ROracle uses the OCI libraries to handle database connections, providing much better performance than standard ODBC.The latest ROracle enhancements include: Support for Oracle TimesTen In-Memory Database Support for Date-Time using R's POSIXct/POSIXlt data types RAW, BLOB and BFILE data type support Option to specify number of rows per fetch operation Option to prefetch LOB data Break support using Ctrl-C Statement caching support Times Ten 11.2.2 contains enhanced support for analytics workloads and complex queries: Analytic functions: AVG, SUM, COUNT, MAX, MIN, DENSE_RANK, RANK, ROW_NUMBER, FIRST_VALUE and LAST_VALUE Analytic clauses: OVER PARTITION BY and OVER ORDER BY Multidimensional grouping operators: Grouping clauses: GROUP BY CUBE, GROUP BY ROLLUP, GROUP BY GROUPING SETS Grouping functions: GROUP, GROUPING_ID, GROUP_ID WITH clause, which allows repeated references to a named subquery block Aggregate expressions over DISTINCT expressions General expressions that return a character string in the source or a pattern within the LIKE predicate Ability to order nulls first or last in a sort result (NULLS FIRST or NULLS LAST in the ORDER BY clause) Note: Some functionality is only available with Oracle Exalytics, refer to the TimesTen product licensing document for details. Connecting to TimesTen is easy with ROracle. Simply install and load the ROracle package and load the driver. > install.packages("ROracle") > library(ROracle) Loading required package: DBI > drv <- dbDriver("Oracle") Once the ROracle package is installed, create a database connection object and connect to a TimesTen direct driver DSN as the OS user. > conn <- dbConnect(drv, username ="", password="", dbname = "localhost/SampleDb_1122:timesten_direct") You have the option to report the server type - Oracle or TimesTen? > print (paste ("Server type =", dbGetInfo (conn)$serverType)) [1] "Server type = TimesTen IMDB" To create tables in the database using R data frame objects, use the function dbWriteTable. In the following example we write the built-in iris data frame to TimesTen. The iris data set is a small example data set containing 150 rows and 5 columns. We include it here not to highlight performance, but so users can easily run this example in their R session. > dbWriteTable (conn, "IRIS", iris, overwrite=TRUE, ora.number=FALSE) [1] TRUE Verify that the newly created IRIS table is available in the database. To list the available tables and table columns in the database, use dbListTables and dbListFields, respectively. > dbListTables (conn) [1] "IRIS" > dbListFields (conn, "IRIS") [1] "SEPAL.LENGTH" "SEPAL.WIDTH" "PETAL.LENGTH" "PETAL.WIDTH" "SPECIES" To retrieve a summary of the data from the database we need to save the results to a local object. The following call saves the results of the query as a local R object, iris.summary. The ROracle function dbGetQuery is used to execute an arbitrary SQL statement against the database. When connected to TimesTen, the SQL statement is processed completely within main memory for the fastest response time. > iris.summary <- dbGetQuery(conn, 'SELECT SPECIES, AVG ("SEPAL.LENGTH") AS AVG_SLENGTH, AVG ("SEPAL.WIDTH") AS AVG_SWIDTH, AVG ("PETAL.LENGTH") AS AVG_PLENGTH, AVG ("PETAL.WIDTH") AS AVG_PWIDTH FROM IRIS GROUP BY ROLLUP (SPECIES)') > iris.summary SPECIES AVG_SLENGTH AVG_SWIDTH AVG_PLENGTH AVG_PWIDTH 1 setosa 5.006000 3.428000 1.462 0.246000 2 versicolor 5.936000 2.770000 4.260 1.326000 3 virginica 6.588000 2.974000 5.552 2.026000 4 <NA> 5.843333 3.057333 3.758 1.199333 Finally, disconnect from the TimesTen Database. > dbCommit (conn) [1] TRUE > dbDisconnect (conn) [1] TRUE We encourage you download Oracle software for evaluation from the Oracle Technology Network. See these links for our software: Times Ten In-Memory Database,  ROracle.  As always, we welcome comments and questions on the TimesTen and  Oracle R technical forums.

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• When is my View too smart?

  - by Kyle Burns

  In this posting, I will discuss the motivation behind keeping View code as thin as possible when using patterns such as MVC, MVVM, and MVP.  Once the motivation is identified, I will examine some ways to determine whether a View contains logic that belongs in another part of the application.  While the concepts that I will discuss are applicable to most any pattern which favors a thin View, any concrete examples that I present will center on ASP.NET MVC. Design patterns that include a Model, a View, and other components such as a Controller, ViewModel, or Presenter are not new to application development.  These patterns have, in fact, been around since the early days of building applications with graphical interfaces.  The reason that these patterns emerged is simple – the code running closest to the user tends to be littered with logic and library calls that center around implementation details of showing and manipulating user interface widgets and when this type of code is interspersed with application domain logic it becomes difficult to understand and much more difficult to adequately test.  By removing domain logic from the View, we ensure that the View has a single responsibility of drawing the screen which, in turn, makes our application easier to understand and maintain. I was recently asked to take a look at an ASP.NET MVC View because the developer reviewing it thought that it possibly had too much going on in the view.  I looked at the .CSHTML file and the first thing that occurred to me was that it began with 40 lines of code declaring member variables and performing the necessary calculations to populate these variables, which were later either output directly to the page or used to control some conditional rendering action (such as adding a class name to an HTML element or not rendering another element at all).  This exhibited both of what I consider the primary heuristics (or code smells) indicating that the View is too smart: Member variables – in general, variables in View code are an indication that the Model to which the View is being bound is not sufficient for the needs of the View and that the View has had to augment that Model.  Notable exceptions to this guideline include variables used to hold information specifically related to rendering (such as a dynamically determined CSS class name or the depth within a recursive structure for indentation purposes) and variables which are used to facilitate looping through collections while binding. Arithmetic – as with member variables, the presence of arithmetic operators within View code are an indication that the Model servicing the View is insufficient for its needs.  For example, if the Model represents a line item in a sales order, it might seem perfectly natural to “normalize” the Model by storing the quantity and unit price in the Model and multiply these within the View to show the line total.  While this does seem natural, it introduces a business rule to the View code and makes it impossible to test that the rounding of the result meets the requirement of the business without executing the View.  Within View code, arithmetic should only be used for activities such as incrementing loop counters and calculating element widths. In addition to the two characteristics of a “Smart View” that I’ve discussed already, this View also exhibited another heuristic that commonly indicates to me the need to refactor a View and make it a bit less smart.  That characteristic is the existence of Boolean logic that either does not work directly with properties of the Model or works with too many properties of the Model.  Consider the following code and consider how logic that does not work directly with properties of the Model is just another form of the “member variable” heuristic covered earlier: @if(DateTime.Now.Hour < 12) {     <div>Good Morning!</div> } else {     <div>Greetings</div> } This code performs business logic to determine whether it is morning.  A possible refactoring would be to add an IsMorning property to the Model, but in this particular case there is enough similarity between the branches that the entire branching structure could be collapsed by adding a Greeting property to the Model and using it similarly to the following: <div>@Model.Greeting</div> Now let’s look at some complex logic around multiple Model properties: @if (ModelPageNumber + Model.NumbersToDisplay == Model.PageCount         || (Model.PageCount != Model.CurrentPage             && !Model.DisplayValues.Contains(Model.PageCount))) {     <div>There's more to see!</div> } In this scenario, not only is the View code difficult to read (you shouldn’t have to play “human compiler” to determine the purpose of the code), but it also complex enough to be at risk for logical errors that cannot be detected without executing the View.  Conditional logic that requires more than a single logical operator should be looked at more closely to determine whether the condition should be evaluated elsewhere and exposed as a single property of the Model.  Moving the logic above outside of the View and exposing a new Model property would simplify the View code to: @if(Model.HasMoreToSee) {     <div>There’s more to see!</div> } In this posting I have briefly discussed some of the more prominent heuristics that indicate a need to push code from the View into other pieces of the application.  You should now be able to recognize these symptoms when building or maintaining Views (or the Models that support them) in your applications.

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• Windows in StreamInsight: Hopping vs. Snapshot

  - by Roman Schindlauer

  Three weeks ago, we explained the basic concept of windows in StreamInsight: defining sets of events that serve as arguments for set-based operations, like aggregations. Today, we want to discuss the so-called Hopping Windows and compare them with Snapshot Windows. We will compare these two, because they can serve similar purposes with different behaviors; we will discuss the remaining window type, Count Windows, another time. Hopping (and its syntactic-sugar-sister Tumbling) windows are probably the most straightforward windowing concept in StreamInsight. A hopping window is defined by its length, and the offset from one window to the next. They are aligned with some absolute point on the timeline (which can also be given as a parameter to the window) and create sets of events. The diagram below shows an example of a hopping window with length of 1h and hop size (the offset) of 15 minutes, hence creating overlapping windows:   Two aspects in this diagram are important: Since this window is overlapping, an event can fall into more than one windows. If an (interval) event spans a window boundary, its lifetime will be clipped to the window, before it is passed to the set-based operation. That’s the default and currently only available window input policy. (This should only concern you if you are using a time-sensitive user-defined aggregate or operator.) The set-based operation will be applied to each of these sets, yielding a result. This result is: A single scalar value in case of built-in or user-defined aggregates. A subset of the input payloads, in case of the TopK operator. Arbitrary events, when using a user-defined operator. The timestamps of the result are almost always the ones of the windows. Only the user-defined  operator can create new events with timestamps. (However, even these event lifetimes are subject to the window’s output policy, which is currently always to clip to the window end.) Let’s assume we were calculating the sum over some payload field: var result = from window in source.HoppingWindow( TimeSpan.FromHours(1), TimeSpan.FromMinutes(15), HoppingWindowOutputPolicy.ClipToWindowEnd) select new { avg = window.Avg(e => e.Value) }; Now each window is reflected by one result event:   As you can see, the window definition defines the output frequency. No matter how many or few events we got from the input, this hopping window will produce one result every 15 minutes – except for those windows that do not contain any events at all, because StreamInsight window operations are empty-preserving (more about that another time). The “forced” output for every window can become a performance issue if you have a real-time query with many events in a wide group & apply – let me explain: imagine you have a lot of events that you group by and then aggregate within each group – classical streaming pattern. The hopping window produces a result in each group at exactly the same point in time for all groups, since the window boundaries are aligned with the timeline, not with the event timestamps. This means that the query output will become very bursty, delivering the results of all the groups at the same point in time. This becomes especially obvious if the events are long-lasting, spanning multiple windows each, so that the produced result events do not change their value very often. In such a case, a snapshot window can remedy. Snapshot windows are more difficult to explain than hopping windows: they represent those periods in time, when no event changes occur. In other words, if you mark all event start and and times on your timeline, then you are looking at all snapshot window boundaries:   If your events are never overlapping, the snapshot window will not make much sense. It is commonly used together with timestamp modification, which make it a very powerful tool. Or as Allan Mitchell expressed in in a recent tweet: “I used to look at SnapshotWindow() with disdain. Now she is my mistress, the one I turn to in times of trouble and need”. Let’s look at a simple example: I want to compute the average of some value in my events over the last minute. I don’t want this output be produced at fixed intervals, but at soon as it changes (that’s the true event-driven spirit!). The snapshot window will include all currently active event at each point in time, hence we need to extend our original events’ lifetimes into the future: Applying the Snapshot window on these events, it will appear to be “looking back into the past”: If you look at the result produced in this diagram, you can easily prove that, at each point in time, the current event value represents the average of all original input event within the last minute. Here is the LINQ representation of that query, applying the lifetime extension before the snapshot window: var result = from window in source .AlterEventDuration(e => TimeSpan.FromMinutes(1)) .SnapshotWindow(SnapshotWindowOutputPolicy.Clip) select new { avg = window.Avg(e => e.Value) }; With more complex modifications of the event lifetimes you can achieve many more query patterns. For instance “running totals” by keeping the event start times, but snapping their end times to some fixed time, like the end of the day. Each snapshot then “sees” all events that have happened in the respective time period so far. Regards, The StreamInsight Team

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• Silverlight Reporting Application Part 3.5 - Prism Background and WCF RIA [Series Intermission]

  Taking a step back before I dive into the details and full-on coding fun, I wanted to once again respond to a comment on my last post to clear up some things in regards to how I'm setting up my project and some of the choices I've made. Aka, thanks Ben. :) Prism Project Setup For starters, I'm not the ideal use case for a Prism application. In most cases where you've got a one-man team, Prism can be overkill as it is more intended for large teams who are geographically dispersed or in applications that have a larger scale than my Recruiting application in which you'll greatly benefit from modularity, delayed loading of xaps, etc. What Prism offers, though, is a manner for handling UI, commands, and events with the idea that, through a modular approach in which no parts really need to know about one another, I can update this application bit by bit as hiring needs change or requirements differ between offices without having to worry that changing something in the Jobs module will break something in, say, the Scheduling module. All that being said, here's a look at how our project breakdown for Recruit (MVVM/Prism implementation) looks: This could be a little misleading though, as each of those modules is actually another project in the overall Recruit solution. As far as what the projects actually are, that looks a bit like this: Recruiting Solution Recruit (Shell up there) - Main Silverlight Application .Web - Default .Web application to host the Silverlight app Infrastructure - Silverlight Class Library Project Modules - Silverlight Class Library Projects Infrastructure &Modules The Infrastructure project is probably something you'll see to some degree in any composite application. In this application, it is going to contain custom commands (you'll see the joy of these in a post or two down the road), events, helper classes, and any custom classes I need to share between different modules. Think of this as a handy little crossroad between any parts of your application. Modules on the other hand are the bread and butter of this application. Besides the shell, which holds the UI skeleton, and the infrastructure, which holds all those shared goodies, the modules are self-contained bundles of functionality to handle different concerns. In my scenario, I need a way to look up and edit Jobs, Applicants, and Schedule interviews, a Notification module to handle telling the user when different things are happening (i.e., loading from database), and a Menu to control interaction and moving between different views. All modules are going to follow the following pattern: The module class will inherit from IModule and handle initialization and loading the correct view into the correct region, whereas the Views and ViewModels folders will contain paired Silverlight user controls and ViewModel class backings. WCF RIA Services Since we've got all the projects in a single solution, we did not have to go the route of creating a WCR RIA Services Class Library. Every module has it's WCF RIA link back to the main .Web project, so the single Linq-2-SQL (yes, I said Linq-2-SQL, but I'll soon be switching to OpenAccess due to the new visual designer) context I'm using there works nicely with the scope of my project. If I were going for completely separating this project out and doing different, dynamically loaded elements, I'd probably go for the separate class library. Hope that clears that up. In the future though, I will be using that in a project that I've got in the "when I've got enough time to work on this" pipeline, so we'll get into that eventually- and hopefully when WCF RIA is in full release! Why Not use Silverlight Navigation/Business Template? The short answer- I'm a creature of habit, and having used Silverlight for a few years now, I'm used to doing lots of things manually. :) Plus, starting with a blank slate of a project I'm able to set up things exactly as I want them to be. In this case, rather than the navigation frame we would see in one of the templates, the MainRegion/ContentControl is working as our main navigation window. In many cases I will use theSilverlight navigation template to start things off, however in this case I did not need those features so I opted out of using that. Next time when I actually hit post #4, we're going to get into the modules and starting to get functionality into this application. Next week is also release week for the Q1 2010 release, so be sure to check out our annualWebinar Week (I might be biased, but Wednesday is my favorite out of the group). Did you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take a look: here.

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• Not getting desired results with SSAO implementation

  - by user1294203

  After having implemented deferred rendering, I tried my luck with a SSAO implementation using this Tutorial. Unfortunately, I'm not getting anything that looks like SSAO, you can see my result below. You can see there is some weird pattern forming and there is no occlusion shading where there needs to be (i.e. in between the objects and on the ground). The shaders I implemented follow: #VS #version 330 core uniform mat4 invProjMatrix; layout(location = 0) in vec3 in_Position; layout(location = 2) in vec2 in_TexCoord; noperspective out vec2 pass_TexCoord; smooth out vec3 viewRay; void main(void){ pass_TexCoord = in_TexCoord; viewRay = (invProjMatrix * vec4(in_Position, 1.0)).xyz; gl_Position = vec4(in_Position, 1.0); } #FS #version 330 core uniform sampler2D DepthMap; uniform sampler2D NormalMap; uniform sampler2D noise; uniform vec2 projAB; uniform ivec3 noiseScale_kernelSize; uniform vec3 kernel[16]; uniform float RADIUS; uniform mat4 projectionMatrix; noperspective in vec2 pass_TexCoord; smooth in vec3 viewRay; layout(location = 0) out float out_AO; vec3 CalcPosition(void){ float depth = texture(DepthMap, pass_TexCoord).r; float linearDepth = projAB.y / (depth - projAB.x); vec3 ray = normalize(viewRay); ray = ray / ray.z; return linearDepth * ray; } mat3 CalcRMatrix(vec3 normal, vec2 texcoord){ ivec2 noiseScale = noiseScale_kernelSize.xy; vec3 rvec = texture(noise, texcoord * noiseScale).xyz; vec3 tangent = normalize(rvec - normal * dot(rvec, normal)); vec3 bitangent = cross(normal, tangent); return mat3(tangent, bitangent, normal); } void main(void){ vec2 TexCoord = pass_TexCoord; vec3 Position = CalcPosition(); vec3 Normal = normalize(texture(NormalMap, TexCoord).xyz); mat3 RotationMatrix = CalcRMatrix(Normal, TexCoord); int kernelSize = noiseScale_kernelSize.z; float occlusion = 0.0; for(int i = 0; i < kernelSize; i++){ // Get sample position vec3 sample = RotationMatrix * kernel[i]; sample = sample * RADIUS + Position; // Project and bias sample position to get its texture coordinates vec4 offset = projectionMatrix * vec4(sample, 1.0); offset.xy /= offset.w; offset.xy = offset.xy * 0.5 + 0.5; // Get sample depth float sample_depth = texture(DepthMap, offset.xy).r; float linearDepth = projAB.y / (sample_depth - projAB.x); if(abs(Position.z - linearDepth ) < RADIUS){ occlusion += (linearDepth <= sample.z) ? 1.0 : 0.0; } } out_AO = 1.0 - (occlusion / kernelSize); } I draw a full screen quad and pass Depth and Normal textures. Normals are in RGBA16F with the alpha channel reserved for the AO factor in the blur pass. I store depth in a non linear Depth buffer (32F) and recover the linear depth using: float linearDepth = projAB.y / (depth - projAB.x); where projAB.y is calculated as: and projAB.x as: These are derived from the glm::perspective(gluperspective) matrix. z_n and z_f are the near and far clip distance. As described in the link I posted on the top, the method creates samples in a hemisphere with higher distribution close to the center. It then uses random vectors from a texture to rotate the hemisphere randomly around the Z direction and finally orients it along the normal at the given pixel. Since the result is noisy, a blur pass follows the SSAO pass. Anyway, my position reconstruction doesn't seem to be wrong since I also tried doing the same but with the position passed from a texture instead of being reconstructed. I also tried playing with the Radius, noise texture size and number of samples and with different kinds of texture formats, with no luck. For some reason when changing the Radius, nothing changes. Does anyone have any suggestions? What could be going wrong?

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• How customers view and interact with a company

  The Harvard Business Review article written by Rayport and Jaworski is aptly titled “Best Face Forward” because it sheds light on how customers view and interact with a company. In the past most business interaction between customers was performed in a face to face meeting where one party would present an item for sale and then the other would decide whether to purchase the item. In addition, if there was a problem with a purchased item then they would bring the item back to the person who sold the item for resolution. One of my earliest examples of witnessing this was when I was around 6 or 7 years old and I was allowed to spend the summer in Tennessee with my Grandparents. My Grandfather had just written a book about the local history of his town and was selling them to his friends and local bookstores. I still remember he offered to pay me a small commission for every book I helped him sell because I was carrying the books around for him. Every sale he made was face to face with his customers which allowed him to share his excitement for the book with everyone. In today’s modern world there is less and less human interaction as the use of computers and other technologies allow us to communicate within seconds even though both parties may be across the globe or just next door. That being said, customers view a company through multiple access points called faces that represent the ability to interact without actually seeing a human face. As a software engineer this is a good and a bad thing because direct human interaction and technology based interaction have both good and bad attributes based on the customer. How organizations coordinate business and IT functions, to provide quality service varies based on each individual business and the goals and directives put in place by its management. According to Rayport and Jaworski, the type of interaction used through a particular access point may lend itself to be people-dominate, machine-dominate, or a combination of both. The method by which a company communicates information through an access point is a strategic choice that relates costs and customer outcomes. To simplify this, the choice is based on what can give the customer the best experience interacting with the company when the cost of the interaction is also a factor. I personally see examples of this every day at work. The company website is machine-dominate with people updating and maintaining information, our groups department is people dominate because most of the customer interaction is done at the customers location and is backed up by machine based data sources, and our sales/member service department is a hybrid because employees work in tandem with machines in order for them to assist customers with signing up or any other issue they may have. The positive and negative aspects of human and machine interfaces are a key aspect in deciding which interface to use when allowing customers to access a company or a combination of the two. Rayport and Jaworski also used MIT professor Erik Brynjolfsson preliminary catalog of human and machine strengths. He stated that humans outperform machines in judgment, pattern recognition, exception processing, insight, and creativity. I have found this to be true based on the example of how sales and member service reps at my company handle a multitude of questions and various situations with a lot of unknown variables. A machine interface could never effectively be able to handle these scenarios because there are too many variables to consider and would not have the built-in logic to process each customer’s claims and needs. In addition, he also stated that machines outperform humans in collecting, storing, transmitting and routine processing. An example of this would be my employer’s website. Customers can simply go online and purchase a product without even talking to a sales or member services representative. The information is then stored in a database so that the customer can always go back and review there order, and access their selected services. A human, no matter how smart they are would never be able to keep track of hundreds of thousands of customers let alone know what they purchased or how much they paid. In today’s technology driven economy every company must offer their customers multiple methods of accessibly in order to survive. The more of an opportunity a company has to create a positive experience for their customers, in my opinion, they more likely the customer will return to that company again. I have noticed this with my personal shopping habits and experiences. References Rayport, J., & Jaworski, B. (2004). Best Face Forward. Harvard Business Review, 82(12), 47-58. Retrieved from Business Source Complete database.

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• Computer Networks UNISA - Chap 8 &ndash; Wireless Networking

  - by MarkPearl

  After reading this section you should be able to Explain how nodes exchange wireless signals Identify potential obstacles to successful transmission and their repercussions, such as interference and reflection Understand WLAN architecture Specify the characteristics of popular WLAN transmission methods including 802.11 a/b/g/n Install and configure wireless access points and their clients Describe wireless MAN and WAN technologies, including 802.16 and satellite communications The Wireless Spectrum All wireless signals are carried through the air by electromagnetic waves. The wireless spectrum is a continuum of the electromagnetic waves used for data and voice communication. The wireless spectrum falls between 9KHZ and 300 GHZ. Characteristics of Wireless Transmission Antennas Each type of wireless service requires an antenna specifically designed for that service. The service’s specification determine the antenna’s power output, frequency, and radiation pattern. A directional antenna issues wireless signals along a single direction. An omnidirectional antenna issues and receives wireless signals with equal strength and clarity in all directions The geographical area that an antenna or wireless system can reach is known as its range Signal Propagation LOS (line of sight) uses the least amount of energy and results in the reception of the clearest possible signal. When there is an obstacle in the way, the signal may… pass through the object or be obsrobed by the object or may be subject to reflection, diffraction or scattering. Reflection – waves encounter an object and bounces off it. Diffraction – signal splits into secondary waves when it encounters an obstruction Scattering – is the diffusion or the reflection in multiple different directions of a signal Signal Degradation Fading occurs as a signal hits various objects. Because of fading, the strength of the signal that reaches the receiver is lower than the transmitted signal strength. The further a signal moves from its source, the weaker it gets (this is called attenuation) Signals are also affected by noise – the electromagnetic interference) Interference can distort and weaken a wireless signal in the same way that noise distorts and weakens a wired signal. Frequency Ranges Older wireless devices used the 2.4 GHZ band to send and receive signals. This had 11 communication channels that are unlicensed. Newer wireless devices can also use the 5 GHZ band which has 24 unlicensed bands Narrowband, Broadband, and Spread Spectrum Signals Narrowband – a transmitter concentrates the signal energy at a single frequency or in a very small range of frequencies Broadband – uses a relatively wide band of the wireless spectrum and offers higher throughputs than narrowband technologies The use of multiple frequencies to transmit a signal is known as spread-spectrum technology. In other words a signal never stays continuously within one frequency range during its transmission. One specific implementation of spread spectrum is FHSS (frequency hoping spread spectrum). Another type is known as DSS (direct sequence spread spectrum) Fixed vs. Mobile Each type of wireless communication falls into one of two categories Fixed – the location of the transmitted and receiver do not move (results in energy saved because weaker signal strength is possible with directional antennas) Mobile – the location can change WLAN (Wireless LAN) Architecture There are two main types of arrangements Adhoc – data is sent directly between devices – good for small local devices Infrastructure mode – a wireless access point is placed centrally, that all devices connect with 802.11 WLANs The most popular wireless standards used on contemporary LANs are those developed by IEEE’s 802.11 committee. Over the years several distinct standards related to wireless networking have been released. Four of the best known standards are also referred to as Wi-Fi. They are…. 802.11b 802.11a 802.11g 802.11n These four standards share many characteristics. i.e. All 4 use half duplex signalling Follow the same access method Access Method 802.11 standards specify the use of CSMA/CA (Carrier Sense Multiple Access with Collision Avoidance) to access a shared medium. Using CSMA/CA before a station begins to send data on an 802.11 network, it checks for existing wireless transmissions. If the source node detects no transmission activity on the network, it waits a brief period of time and then sends its transmission. If the source does detect activity, it waits a brief period of time before checking again. The destination node receives the transmission and, after verifying its accuracy, issues an acknowledgement (ACT) packet to the source. If the source receives the ACK it assumes the transmission was successful, – if it does not receive an ACK it assumes the transmission failed and sends it again. Association Two types of scanning… Active – station transmits a special frame, known as a prove, on all available channels within its frequency range. When an access point finds the probe frame, it issues a probe response. Passive – wireless station listens on all channels within its frequency range for a special signal, known as a beacon frame, issued from an access point – the beacon frame contains information necessary to connect to the point. Re-association occurs when a mobile user moves out of one access point’s range and into the range of another. Frames Read page 378 – 381 about frames and specific 802.11 protocols Bluetooth Networks Sony Ericson originally invented the Bluetooth technology in the early 1990s. In 1998 other manufacturers joined Ericsson in the Special Interest Group (SIG) whose aim was to refine and standardize the technology. Bluetooth was designed to be used on small networks composed of personal communications devices. It has become popular wireless technology for communicating among cellular telephones, phone headsets, etc. Wireless WANs and Internet Access Refer to pages 396 – 402 of the textbook for details.

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• ROracle support for TimesTen In-Memory Database

  - by Sherry LaMonica

  Today's guest post comes from Jason Feldhaus, a Consulting Member of Technical Staff in the TimesTen Database organization at Oracle.  He shares with us a sample session using ROracle with the TimesTen In-Memory database.  Beginning in version 1.1-4, ROracle includes support for the Oracle Times Ten In-Memory Database, version 11.2.2. TimesTen is a relational database providing very fast and high throughput through its memory-centric architecture.  TimesTen is designed for low latency, high-volume data, and event and transaction management. A TimesTen database resides entirely in memory, so no disk I/O is required for transactions and query operations. TimesTen is used in applications requiring very fast and predictable response time, such as real-time financial services trading applications and large web applications. TimesTen can be used as the database of record or as a relational cache database to Oracle Database. ROracle provides an interface between R and the database, providing the rich functionality of the R statistical programming environment using the SQL query language. ROracle uses the OCI libraries to handle database connections, providing much better performance than standard ODBC.The latest ROracle enhancements include: Support for Oracle TimesTen In-Memory Database Support for Date-Time using R's POSIXct/POSIXlt data types RAW, BLOB and BFILE data type support Option to specify number of rows per fetch operation Option to prefetch LOB data Break support using Ctrl-C Statement caching support Times Ten 11.2.2 contains enhanced support for analytics workloads and complex queries: Analytic functions: AVG, SUM, COUNT, MAX, MIN, DENSE_RANK, RANK, ROW_NUMBER, FIRST_VALUE and LAST_VALUE Analytic clauses: OVER PARTITION BY and OVER ORDER BY Multidimensional grouping operators: Grouping clauses: GROUP BY CUBE, GROUP BY ROLLUP, GROUP BY GROUPING SETS Grouping functions: GROUP, GROUPING_ID, GROUP_ID WITH clause, which allows repeated references to a named subquery block Aggregate expressions over DISTINCT expressions General expressions that return a character string in the source or a pattern within the LIKE predicate Ability to order nulls first or last in a sort result (NULLS FIRST or NULLS LAST in the ORDER BY clause) Note: Some functionality is only available with Oracle Exalytics, refer to the TimesTen product licensing document for details. Connecting to TimesTen is easy with ROracle. Simply install and load the ROracle package and load the driver. > install.packages("ROracle") > library(ROracle) Loading required package: DBI > drv <- dbDriver("Oracle") Once the ROracle package is installed, create a database connection object and connect to a TimesTen direct driver DSN as the OS user. > conn <- dbConnect(drv, username ="", password="", dbname = "localhost/SampleDb_1122:timesten_direct") You have the option to report the server type - Oracle or TimesTen? > print (paste ("Server type =", dbGetInfo (conn)$serverType)) [1] "Server type = TimesTen IMDB" To create tables in the database using R data frame objects, use the function dbWriteTable. In the following example we write the built-in iris data frame to TimesTen. The iris data set is a small example data set containing 150 rows and 5 columns. We include it here not to highlight performance, but so users can easily run this example in their R session. > dbWriteTable (conn, "IRIS", iris, overwrite=TRUE, ora.number=FALSE) [1] TRUE Verify that the newly created IRIS table is available in the database. To list the available tables and table columns in the database, use dbListTables and dbListFields, respectively. > dbListTables (conn) [1] "IRIS" > dbListFields (conn, "IRIS") [1] "SEPAL.LENGTH" "SEPAL.WIDTH" "PETAL.LENGTH" "PETAL.WIDTH" "SPECIES" To retrieve a summary of the data from the database we need to save the results to a local object. The following call saves the results of the query as a local R object, iris.summary. The ROracle function dbGetQuery is used to execute an arbitrary SQL statement against the database. When connected to TimesTen, the SQL statement is processed completely within main memory for the fastest response time. > iris.summary <- dbGetQuery(conn, 'SELECT SPECIES, AVG ("SEPAL.LENGTH") AS AVG_SLENGTH, AVG ("SEPAL.WIDTH") AS AVG_SWIDTH, AVG ("PETAL.LENGTH") AS AVG_PLENGTH, AVG ("PETAL.WIDTH") AS AVG_PWIDTH FROM IRIS GROUP BY ROLLUP (SPECIES)') > iris.summary SPECIES AVG_SLENGTH AVG_SWIDTH AVG_PLENGTH AVG_PWIDTH 1 setosa 5.006000 3.428000 1.462 0.246000 2 versicolor 5.936000 2.770000 4.260 1.326000 3 virginica 6.588000 2.974000 5.552 2.026000 4 <NA> 5.843333 3.057333 3.758 1.199333 Finally, disconnect from the TimesTen Database. > dbCommit (conn) [1] TRUE > dbDisconnect (conn) [1] TRUE We encourage you download Oracle software for evaluation from the Oracle Technology Network. See these links for our software: Times Ten In-Memory Database,  ROracle.  As always, we welcome comments and questions on the TimesTen and  Oracle R technical forums.

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• jQuery Templates, Data Link

  - by Renso

  Normal 0 false false false EN-US X-NONE X-NONE /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin-top:0in; mso-para-margin-right:0in; mso-para-margin-bottom:10.0pt; mso-para-margin-left:0in; line-height:115%; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;} Query Templates, Data Link, and Globalization I am sure you must have read Scott Guthrie’s blog post about jQuery support and officially supporting jQuery's templating, data linking and globalization, if not here it is: jQuery Templating Since we are an open source shop and use jQuery and jQuery plugins extensively to say the least, decided to look into the templating a bit and see what data linking is all about. For those not familiar with those terms here is the summary, plenty of material out there on what it is, but here is what in my experience it means: jQuery Templating: A templating engine that allows you to specify a client-side template where you indicate which properties/tags you want dynamically updated. You in a sense specify which parts of the html is dynamic and since it is pluggable you are able to use tools data jQuery data linking and others to let it sync up your template with data. What makes it more powerful is that you can easily work with rows of data, adding and removing rows. Once the template has been generated, which you do dynamically on a client-side event, you then append/inject the resulting template somewhere in your DOM, like for example you would get a JSON object from the database, map it to your template, it populates the template with your data in the indicated places, and then let’s say for example append it to a row in a table. I have not found it that useful for lets say a single record of data since you could easily just get a partial view from the server via an html type ajax call. It really shines when you dynamically add/remove rows from a list in the DOM. I have not found an alternative that meets the functionality of the jQuery template and helps of course that Microsoft officially supports it. In future versions of the jQuery plug-in it may even ship as part of the standard jQuery library and with future versions of Visual Studio. jQuery Data Linking: In short I was fascinated by it initially by how with one line of code I can sync up my JSON object with my form elements. That's where my enthusiasm stopped. It was one-line to let is deal with syncing up your form with your JSON object, but it is not bidirectional as they state and I tried all the work arounds they suggested and none of them work. The problem is that when you update your JSON object it DOES NOT sync it up with your form. In an example, accounts are being edited client side by selecting the account from a list by clicking on the row, it then fetches the entire account JSON object via ajax json-type call and then refreshes the form with the account’s details from the new JSON object. What is the use of syncing up my JSON with the form if I still have to programmatically sync up my new JSON object with each DOM property?! So you may ask: “what is the alternative”? Good question and the same one I was pondering, maybe I can just use it for keeping my from n sync with my JSON object so I can post that JSON object back to the server and update my database. That’s when I discovered Knockout: Knockout It addresses the issues mentioned above and also supports event handling through the observer pattern. Not wanting to go into detail here, Steve Sanderson, the creator of Knockout, has already done a terrific job of that, thanks Steve for a great plug-in! Best of all it integrates perfectly with the jQuery Templating engine as well. I have not found an alternative to this plugin that supports the depth and width of functionality and would recommend it to anyone. The only drawback is the embedded html attributes (data-bind=””) tags that you have to add to the HTML, in my opinion tying your behavior to your HTML, where I like to separate behavior from HTML as well as CSS, so the HTML is purely to define content, not styling or behavior. But there are plusses to this as well and also a nifty work around to this that I will just shortly mention here with an example. Instead of data binding an html tag with knockout event handling like so:  <%=Html.TextBox("PrepayDiscount", String.Empty, new { @class = "number" })%>   Do: <%=Html.DataBoundTextBox("PrepayDiscount", String.Empty, new { @class = "number" })%>   The html extension above then takes care of the internals and you could then swap Knockout for something else if you want to inside the extension and keep the HTML plugin agnostic. Here is what the extension looks like, you can easily build a whole library to support all kinds of data binding options from this:      public static class HtmlExtensions       {         public static MvcHtmlString DataBoundTextBox(this HtmlHelper helper, string name, object value, object htmlAttributes)         {             var dic = new RouteValueDictionary(htmlAttributes);             dic.Add("data-bind", String.Format("value: {0}", name));             return helper.TextBox(name, value, dic);         }       }   Hope this helps in making a decision when and where to consider jQuery templating, data linking and Knockout.

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• BizTalk 2009 - Custom Functoid Wizard

  - by StuartBrierley

  When creating BizTalk maps you may find that there are times when you need perform tasks that the standard functoids do not cover.  At other times you may find yourself reapeating a pattern of standard functoids over and over again, adding visual complexity to an otherwise simple process.  In these cases you may find it preferable to create your own custom functoids.  In the past I have created a number of custom functoids from scratch, but recently I decided to try out the Custom Functoid Wizard for BizTalk 2009. After downloading and installing the wizard you should start Visual Studio and select to create a new BizTalk Server Functoid Project. Following the splash screen you will be presented with the General Properties screen, where you can set the classname, namespace, assembly name and strong name key file. The next screen is the first set of properties for the functoid.  First of all is the fuctoid ID; this must be a value above 6000. You should also then set the name, tooltip and description of the functoid.  The name will appear in the visual studio toolbox and the tooltip on hover over in the toolbox.  The descrition will be shown when you configure the functoid inputs when using it in a map; as such it should provide a decent level of information to allow the functoid to be used. Next you must set the category, exception mesage, icon and implementation language.  The category will affect the positioning of the functoid within the toolbox and also some of the behaviours of the functoid. We must then define the parameters and connections for our new functoid.  Here you can define the names and types of your input parameters along with the minimum and maximum number of input connections.  You will also need to define the types of connections accepted and the output type of the functoid. Finally you can click finish and your custom functoid project will be created. The results of this process can be seen in the solution explorer, where you will see that a project, functoid class file and a resource file have been created for you. If you open the class file you will see that the following code has been created for you: The "base" function sets all the properties that you previsouly detailed in the custom functoid wizard.  public TestFunctoids():base()  {    int functoidID;    // This has to be a number greater than 6000    functoidID = System.Convert.ToInt32(resmgr.GetString("FunctoidId"));    this.ID = functoidID;    // Set Resource strings, bitmaps    SetupResourceAssembly(ResourceName, Assembly.GetExecutingAssembly());    SetName("FunctoidName");                     SetTooltip("FunctoidToolTip");    SetDescription("FunctoidDescription");    SetBitmap("FunctoidBitmap");    // Minimum and maximum parameters that the functoid accepts    this.SetMinParams(2);    this.SetMaxParams(2);    /// Function name that needs to be called when this Functoid is invoked.    /// Put this in GAC.    SetExternalFunctionName(GetType().Assembly.FullName,     "MyCompany.BizTalk.Functoids.TestFuntoids.TestFunctoids", "Execute");    // Category for this functoid.    this.Category = FunctoidCategory.String;    // Input and output Connection type    this.OutputConnectionType = ConnectionType.AllExceptRecord;    AddInputConnectionType(ConnectionType.AllExceptRecord);   } The "Execute" function provides a skeleton function that contains the code to be executed by your new functoid.  The inputs and outputs should match those you defined in the Custom Functoid Wizard.   public System.Int32 Execute(System.Int32 Cool)   {    ResourceManager resmgr = new ResourceManager(ResourceName, Assembly.GetExecutingAssembly());    try    {     // TODO: Implement Functoid Logic    }    catch (Exception e)    {     throw new Exception(resmgr.GetString("FunctoidException"), e);    }   } Opening the resource file you will see some of the various string values that you defined in the Custom Functoid Wizard - Name, Tooltip, Description and Exception. You can also select to look at the image resources.  This will display the embedded icon image for the functoid.  To change this right click the icon and select "Import from File". Once you have completed the skeleton code you can then look at trying out your functoid. To do this you will need to build the project, copy the compiled DLL to C:\Program Files\Microsoft BizTalk Server 2009\Developer Tools\Mapper Extensions and then refresh the toolbox in visual studio.

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• Speakers, Please Check Your Time

  - by AjarnMark

  Woodrow Wilson was once asked how long it would take him to prepare for a 10 minute speech. He replied "Two weeks". He was then asked how long it would take for a 1 hour speech. "One week", he replied. 2 hour speech? "I'm ready right now," he replied.  Whether that is a true story or an urban legend, I don’t really know, but either way, it is a poignant reminder for all speakers, and particularly apropos this week leading up to the PASS Community Summit. (Cross-posted to the PASS Professional Development Virtual Chapter blog #PASSProfDev.) What’s the point of that story?  Simply this…if you have plenty of time to do your presentation, you don’t need to prepare much because it is easy to throw in more and more material to stretch out to your allotted time.  But if you are on a tight time constraint, then it will take significant preparation to distill your talk down to only the essential points. I have attended seven of the last eight North American Summit events, and every one of them has been fantastic.  The speakers are great, the material is timely and relevant, and the networking opportunities are awesome.  And every year, there is one little thing that just bugs me…speakers going over their allotted time.  Why does it bother me so?  Well, if you look at a typical schedule for a Summit, you’ll see that there are six or more sessions going on at the same time, and only 15 minutes to move from one to another.  If you’re trying to maximize your training dollar by attending something during every session time slot, and you don’t want to be the last guy trying to squeeze into the middle of the row, then those 15 minutes can be critical.  All the more so if you need to stop and use the bathroom or if you have to hike to the opposite end of the convention center.  It is really a bad position to find yourself having to choose between learning the last key points of Speaker A who is going over time, and getting over to Speaker B on time so you don’t miss her key opening remarks. And frankly, I think it is just rude.  Yes, the speakers are the function, after all they are bringing the content that the rest of us are paying to learn.  But it is also an honor to be given the opportunity to speak at a conference like this, and no one speaker is so important that the conference would be a disaster without him.  Speakers know when they submit their abstract, long before the conference, how much time they will have.  It has been the same pattern at the Summit for at least the last eight years.  Program Sessions are 75 minutes long.  Some speakers who have a good track record, and meet other qualifying criteria, are extended an invitation to present a Spotlight Session which is 90 minutes (a 20% increase).  So there really is no excuse.  It’s not like you were promised a 2-hour segment and then discovered when you got here that it was only 75 minutes.  In fact, it’s not like PASS advertised 90-minute sessions for everyone and then a select few were cut back to only 75.  As a speaker, you know well before you get here which type of session you are doing and how long it is, so as a professional, you should plan accordingly. Now you might think that this only happens to rookies, but I’ll tell you that some of the worst offenders are big-name veterans who draw huge attendance numbers for their sessions.  Some attendees blow this off as, “Hey, it’s so-and-so, and I’d stay here for hours and listen to him/her talk.”  To which I would reply, “Then they should have submitted for a pre- or post-conference day-long seminar instead, but don’t try to squeeze your day-long talk into a 90-minute session.”  Now I don’t really believe that these speakers are being malicious or just selfishly trying to extend their time in the spotlight.  I think that most of them are merely being undisciplined and did not trim their presentation sufficiently, or allowed themselves to get off-track (often in a generous attempt to help someone in the audience with a question or problem that really should have been noted for further discussion after the session). So here is my recommendation…my plea, even.  TRIM THE FAT!  Now.  Before it’s too late.  Before you even get on the airplane, take a long, hard look at your presentation and eliminate some of the points that you originally thought you had to make, but in reality are not truly crucial to your main topic.  Delete a few slides.  Test your demos and have them already scripted rather than typing them during your talk.  It is better to cut out too much and end up with plenty of time at the end for Questions & Answers.  And you can always keep some notes on the stuff that you cut out so that you could fill it back in at the end as bonus material if you really do end up with a whole bunch of time on your hands.  But I don’t think you will.  And if you do, that will look even better to the audience as it will look like you’re giving them something extra that not every audience gets.  And they will thank you for that.

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• Right-Time Retail Part 2

  - by David Dorf

  This is part two of the three-part series. Normal 0 false false false EN-US X-NONE X-NONE /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin-top:0in; mso-para-margin-right:0in; mso-para-margin-bottom:10.0pt; mso-para-margin-left:0in; line-height:115%; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;} Right-Time Integration Of course these real-time enabling technologies are only as good as the systems that utilize them, and it only takes one bottleneck to slow everyone else down. What good is an immediate stock-out notification if the supply chain can’t react until tomorrow? Since being formed in 2006, Oracle Retail has been not only adding more integrations between systems, but also modernizing integrations for appropriate speed. Notice I tossed in the word “appropriate.” Not everything needs to be real-time – again, we’re talking about Right-Time Retail. The speed of data capture, analysis, and execution must be synchronized or you’re wasting effort. Unfortunately, there isn’t an enterprise-wide dial that you can crank-up for your estate. You’ll need to improve things piecemeal, with people and processes as limiting factors while choosing the appropriate types of integrations. There are three integration styles we see in the retail industry. First is batch. I know, the word “batch” just sounds slow, but this pattern is less about velocity and more about volume. When there are large amounts of data to be moved, you’ll want to use batch processes. Our technology of choice here is Oracle Data Integrator (ODI), which provides a fast version of Extract-Transform-Load (ETL). Instead of the three-step process, the load and transform steps are combined to save time. ODI is a key technology for moving data into Retail Analytics where we can apply science. Performing analytics on each sale as it occurs doesn’t make any sense, so we batch up a statistically significant amount and submit all at once. The second style is fire-and-forget. For some types of data, we want the data to arrive ASAP but immediacy is not necessary. Speed is less important than guaranteed delivery, so we use message-oriented middleware available in both Weblogic and the Oracle database. For example, Point-of-Service transactions are queued for delivery to Central Office at corporate. If the network is offline, those transactions remain in the queue and will be delivered when the network returns. Transactions cannot be lost and they must be delivered in order. (Ever tried processing a return before the sale?) To enhance the standard queues, we offer the Retail Integration Bus (RIB) to help the management and monitoring of fire-and-forget messaging in the enterprise. The third style is request-response and is most commonly implemented as Web services. This is a synchronous message where the sender waits for a response. In this situation, the volume of data is small, guaranteed delivery is not necessary, but speed is very important. Examples include the website checking inventory, a price lookup, or processing a credit card authorization. The Oracle Service Bus (OSB) typically handles the routing of such messages, and we’ve enhanced its abilities with the Retail Service Backbone (RSB). To better understand these integration patterns and where they apply within the retail enterprise, we’re providing the Retail Reference Library (RRL) at no charge to Oracle Retail customers. The library is composed of a large number of industry business processes, including those necessary to support Commerce Anywhere, as well as detailed architectural diagrams. These diagrams allow implementers to understand the systems involved in integrations and the specific data payloads. Furthermore, with our upcoming release we’ll be providing a new tool called the Retail Integration Console (RIC) that allows IT to monitor and manage integrations from a single point. Using RIC, retailers can quickly discern where integration activity is occurring, volume statistics, average response times, and errors. The dashboards provide the ability to dive down into the architecture documentation to gather information all the way down to the specific payload. Retailers that want real-time integrations will also need real-time monitoring of those integrations to ensure service-level agreements are maintained. Part 3 looks at marketing.

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• ADF Reusable Artefacts

  - by Arda Eralp

  Primary reusable ADF Business Component: Entity Objects (EOs) View Objects (VOs) Application Modules (AMs) Framework Extensions Classes Primary reusable ADF Controller: Bounded Task Flows (BTFs) Task Flow Templates Primary reusable ADF Faces: Page Templates Skins Declarative Components Utility Classes Certain components will often be used more than once. Whether the reuse happens within the same application, or across different applications, it is often advantageous to package these reusable components into a library that can be shared between different developers, across different teams, and even across departments within an organization. In the world of Java object-oriented programming, reusing classes and objects is just standard procedure. With the introduction of the model-view-controller (MVC) architecture, applications can be further modularized into separate model, view, and controller layers. By separating the data (model and business services layers) from the presentation (view and controller layers), you ensure that changes to any one layer do not affect the integrity of the other layers. You can change business logic without having to change the UI, or redesign the web pages or front end without having to recode domain logic. Oracle ADF and JDeveloper support the MVC design pattern. When you create an application in JDeveloper, you can choose many application templates that automatically set up data model and user interface projects. Because the different MVC layers are decoupled from each other, development can proceed on different projects in parallel and with a certain amount of independence. ADF Library further extends this modularity of design by providing a convenient and practical way to create, deploy, and reuse high-level components. When you first design your application, you design it with component reusability in mind. If you created components that can be reused, you can package them into JAR files and add them to a reusable component repository. If you need a component, you may look into the repository for those components and then add them into your project or application. For example, you can create an application module for a domain and package it to be used as the data model project in several different applications. Or, if your application will be consuming components, you may be able to load a page template component from a repository of ADF Library JARs to create common look and feel pages. Then you can put your page flow together by stringing together several task flow components pulled from the library. An ADF Library JAR contains ADF components and does not, and cannot, contain other JARs. It should not be confused with the JDeveloper library, Java EE library, or Oracle WebLogic shared library. Reusable Component Description Data Control Any data control can be packaged into an ADF Library JAR. Some of the data controls supported by Oracle ADF include application modules, Enterprise JavaBeans, web services, URL services, JavaBeans, and placeholder data controls. Application Module When you are using ADF Business Components and you generate an application module, an associated application module data control is also generated. When you package an application module data control, you also package up the ADF Business Components associated with that application module. The relevant entity objects, view objects, and associations will be a part of the ADF Library JAR and available for reuse. Business Components Business components are the entity objects, view objects, and associations used in the ADF Business Components data model project. You can package business components by themselves or together with an application module. Task Flows & Task Flow Templates Task flows can be packaged into an ADF Library JAR for reuse. If you drop a bounded task flow that uses page fragments, JDeveloper adds a region to the page and binds it to the dropped task flow. ADF bounded task flows built using pages can be dropped onto pages. The drop will create a link to call the bounded task flow. A task flow call activity and control flow will automatically be added to the task flow, with the view activity referencing the page. If there is more than one existing task flow with a view activity referencing the page, it will prompt you to select the one to automatically add a task flow call activity and control flow. If an ADF task flow template was created in the same project as the task flow, the ADF task flow template will be included in the ADF Library JAR and will be reusable. Page Templates You can package a page template and its artifacts into an ADF Library JAR. If the template uses image files and they are included in a directory within your project, these files will also be available for the template during reuse. Declarative Components You can create declarative components and package them for reuse. The tag libraries associated with the component will be included and loaded into the consuming project. You can also package up projects that have several different reusable components if you expect that more than one component will be consumed. For example, you can create a project that has both an application module and a bounded task flow. When this ADF Library JAR file is consumed, the application will have both the application module and the task flow available for use. You can package multiple components into one JAR file, or you can package a single component into a JAR file. Oracle ADF and JDeveloper give you the option and flexibility to create reusable components that best suit you and your organization. You create a reusable component by using JDeveloper to package and deploy the project that contains the components into a ADF Library JAR file. You use the components by adding that JAR to the consuming project. At design time, the JAR is added to the consuming project's class path and so is available for reuse. At runtime, the reused component runs from the JAR file by reference.

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• Proxied calls not working as expected

  - by AndyH

  I have been modifying an application to have a cleaner client/server split to allow for load splitting and resource sharing etc. Everything is written to an interface so it was easy to add a remoting layer to the interface using a proxy. Everything worked fine. The next phase was to add a caching layer to the interface and again this worked fine and speed was improved but not as much as I would have expected. On inspection it became very clear what was going on. I feel sure that this behavior has been seen many times before and there is probably a design pattern to solve the problem but it eludes me and I'm not even sure how to describe it. It is easiest explained with an example. Let's imagine the interface is interface IMyCode { List<IThing> getLots( List<String> ); IThing getOne( String id ); } The getLots() method calls getOne() and fills up the list before returning. The interface is implemented at the client which is proxied to a remoting client which then calls the remoting server which in turn calls the implementation at the server. At the client and the server layers there is also a cache. So we have :- Client interface | Client cache | Remote client | Remote server | Server cache | Server interface If we call getOne("A") at the client interface, the call is passed to the client cache which faults. This then calls the remote client which passes the call to the remote server. This then calls the server cache which also faults and so the call is eventually passed to the server interface which actually gets the IThing. In turn the server cache is filled and finally the client cache also. If getOne("A") is again called at the client interface the client cache has the data and it gets returned immediately. If a second client called getOne("B") it would fill the server cache with "B" as well as it's own client cache. Then, when the first client calls getOne("B") the client cache faults but the server cache has the data. This is all as one would expect and works well. Now lets call getLots( [ "C", "D" ] ). This works as you would expect by calling getOne() twice but there is a subtlety here. The call to getLots() cannot directly make use of the cache. Therefore the sequence is to call the client interface which in turn calls the remote client, then the remote server and eventually the server interface. This then calls getOne() to fill the list before returning. The problem is that the getOne() calls are being satisfied at the server when ideally they should be satisfied at the client. If you imagine that the client/server link is really slow then it becomes clear why the client call is more efficient than the server call once the client cache has the data. This example is contrived to illustrate the point. The more general problem is that you cannot just keep adding proxied layers to an interface and expect it to work as you would imagine. As soon as the call goes 'through' the proxy any subsequent calls are on the proxied side rather than 'self' side. Have I failed to learn or not learned something correctly? All this is implemented in Java and I haven't used EJBs. It seems that the example may be confusing. The problem is nothing to do with cache efficiencies. It is more to do with an illusion created by the use of proxies or AOP techniques in general. When you have an object whose class implements an interface there is an assumption that a call on that object might make further calls on that same object. For example, public String getInternalString() { return InetAddress.getLocalHost().toString(); } public String getString() { return getInternalString(); } If you get an object and call getString() the result depends where the code is running. If you add a remoting proxy to the class then the result could be different for calls to getString() and getInternalString() on the same object. This is because the initial call gets 'deproxied' before the actual method is called. I find this not only confusing but I wonder how I can control this behavior especially as the use of the proxy may be by a third party. The concept is fine but the practice is certainly not what I expected. Have I missed the point somewhere?

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• Cloud Computing Forces Better Design Practices

  - by Herve Roggero

  Is cloud computing simply different than on premise development, or is cloud computing actually forcing you to create better applications than you normally would? In other words, is cloud computing merely imposing different design principles, or forcing better design principles?  A little while back I got into a discussion with a developer in which I was arguing that cloud computing, and specifically Windows Azure in his case, was forcing developers to adopt better design principles. His opinion was that cloud computing was not yielding better systems; just different systems. In this blog, I will argue that cloud computing does force developers to use better design practices, and hence better applications. So the first thing to define, of course, is the word “better”, in the context of application development. Looking at a few definitions online, better means “superior quality”. As it relates to this discussion then, I stipulate that cloud computing can yield higher quality applications in terms of scalability, everything else being equal. Before going further I need to also outline the difference between performance and scalability. Performance and scalability are two related concepts, but they don’t mean the same thing. Scalability is the measure of system performance given various loads. So when developers design for performance, they usually give higher priority to a given load and tend to optimize for the given load. When developers design for scalability, the actual performance at a given load is not as important; the ability to ensure reasonable performance regardless of the load becomes the objective. This can lead to very different design choices. For example, if your objective is to obtains the fastest response time possible for a service you are building, you may choose the implement a TCP connection that never closes until the client chooses to close the connection (in other words, a tightly coupled service from a connectivity standpoint), and on which a connection session is established for faster processing on the next request (like SQL Server or other database systems for example). If you objective is to scale, you may implement a service that answers to requests without keeping session state, so that server resources are released as quickly as possible, like a REST service for example. This alternate design would likely have a slower response time than the TCP service for any given load, but would continue to function at very large loads because of its inherently loosely coupled design. An example of a REST service is the NO-SQL implementation in the Microsoft cloud called Azure Tables. Now, back to cloud computing… Cloud computing is designed to help you scale your applications, specifically when you use Platform as a Service (PaaS) offerings. However it’s not automatic. You can design a tightly-coupled TCP service as discussed above, and as you can imagine, it probably won’t scale even if you place the service in the cloud because it isn’t using a connection pattern that will allow it to scale [note: I am not implying that all TCP systems do not scale; I am just illustrating the scalability concepts with an imaginary TCP service that isn’t designed to scale for the purpose of this discussion]. The other service, using REST, will have a better chance to scale because, by design, it minimizes resource consumption for individual requests and doesn’t tie a client connection to a specific endpoint (which means you can easily deploy this service to hundreds of machines without much trouble, as long as your pockets are deep enough). The TCP and REST services discussed above are both valid designs; the TCP service is faster and the REST service scales better. So is it fair to say that one service is fundamentally better than the other? No; not unless you need to scale. And if you don’t need to scale, then you don’t need the cloud in the first place. However, it is interesting to note that if you do need to scale, then a loosely coupled system becomes a better design because it can almost always scale better than a tightly-coupled system. And because most applications grow overtime, with an increasing user base, new functional requirements, increased data and so forth, most applications eventually do need to scale. So in my humble opinion, I conclude that a loosely coupled system is not just different than a tightly coupled system; it is a better design, because it will stand the test of time. And in my book, if a system stands the test of time better than another, it is of superior quality. Because cloud computing demands loosely coupled systems so that its underlying service architecture can be leveraged, developers ultimately have no choice but to design loosely coupled systems for the cloud. And because loosely coupled systems are better… … the cloud forces better design practices. My 2 cents.

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• Modifying the SL/WIF Integration Bits to support Issued Token Credentials

  - by Your DisplayName here!

  The SL/WIF integration code that ships with the Identity Training Kit only supports Windows and UserName credentials to request tokens from an STS. This is fine for simple single STS scenarios (like a single IdP). But the more common pattern for claims/token based systems is to split the STS roles into an IdP and a Resource STS (or whatever you wanna call it). In this case, the 2nd leg requires to present the issued token from the 1st leg – this is not directly supported by the bits. But they can be easily modified to accomplish this. The Credential Fist we need a class that represents an issued token credential. Here we store the RSTR that got returned from the client to IdP request: public class IssuedTokenCredentials : IRequestCredentials {     public string IssuedToken { get; set; }     public RequestSecurityTokenResponse RSTR { get; set; }     public IssuedTokenCredentials(RequestSecurityTokenResponse rstr)     {         RSTR = rstr;         IssuedToken = rstr.RequestedSecurityToken.RawToken;     } } The Binding Next we need a binding to be used with issued token credential requests. This assumes you have an STS endpoint for mixed mode security with SecureConversation turned off. public class WSTrustBindingIssuedTokenMixed : WSTrustBinding {     public WSTrustBindingIssuedTokenMixed()     {         this.Elements.Add( new HttpsTransportBindingElement() );     } } WSTrustClient The last step is to make some modifications to WSTrustClient to make it issued token aware. In the constructor you have to check for the credential type, and if it is an issued token, store it away. private RequestSecurityTokenResponse _rstr; public WSTrustClient( Binding binding, EndpointAddress remoteAddress, IRequestCredentials credentials )     : base( binding, remoteAddress ) {     if ( null == credentials )     {         throw new ArgumentNullException( "credentials" );     }     if (credentials is UsernameCredentials)     {         UsernameCredentials usernname = credentials as UsernameCredentials;         base.ChannelFactory.Credentials.UserName.UserName = usernname.Username;         base.ChannelFactory.Credentials.UserName.Password = usernname.Password;     }     else if (credentials is IssuedTokenCredentials)     {         var issuedToken = credentials as IssuedTokenCredentials;         _rstr = issuedToken.RSTR;     }     else if (credentials is WindowsCredentials)     { }     else     {         throw new ArgumentOutOfRangeException("credentials", "type was not expected");     } } Next – when WSTrustClient constructs the RST message to the STS, the issued token header must be embedded when needed: private Message BuildRequestAsMessage( RequestSecurityToken request ) {     var message = Message.CreateMessage( base.Endpoint.Binding.MessageVersion ?? MessageVersion.Default,       IssueAction,       (BodyWriter) new WSTrustRequestBodyWriter( request ) );     if (_rstr != null)     {         message.Headers.Add(new IssuedTokenHeader(_rstr));     }     return message; } HTH

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• Coherence Data Guarantees for Data Reads - Basic Terminology

  - by jpurdy

  When integrating Coherence into applications, each application has its own set of requirements with respect to data integrity guarantees. Developers often describe these requirements using expressions like "avoiding dirty reads" or "making sure that updates are transactional", but we often find that even in a small group of people, there may be a wide range of opinions as to what these terms mean. This may simply be due to a lack of familiarity, but given that Coherence sits at an intersection of several (mostly) unrelated fields, it may be a matter of conflicting vocabularies (e.g. "consistency" is similar but different in transaction processing versus multi-threaded programming). Since almost all data read consistency issues are related to the concept of concurrency, it is helpful to start with a definition of that, or rather what it means for two operations to be concurrent. Rather than implying that they occur "at the same time", concurrency is a slightly weaker statement -- it simply means that it can't be proven that one event precedes (or follows) the other. As an example, in a Coherence application, if two client members mutate two different cache entries sitting on two different cache servers at roughly the same time, it is likely that one update will precede the other by a significant amount of time (say 0.1ms). However, since there is no guarantee that all four members have their clocks perfectly synchronized, and there is no way to precisely measure the time it takes to send a given message between any two members (that have differing clocks), we consider these to be concurrent operations since we can not (easily) prove otherwise. So this leads to a question that we hear quite frequently: "Are the contents of the near cache always synchronized with the underlying distributed cache?". It's easy to see that if an update on a cache server results in a message being sent to each near cache, and then that near cache being updated that there is a window where the contents are different. However, this is irrelevant, since even if the application reads directly from the distributed cache, another thread update the cache before the read is returned to the application. Even if no other member modifies a cache entry prior to the local near cache entry being updated (and subsequently read), the purpose of reading a cache entry is to do something with the result, usually either displaying for consumption by a human, or by updating the entry based on the current state of the entry. In the former case, it's clear that if the data is updated faster than a human can perceive, then there is no problem (and in many cases this can be relaxed even further). For the latter case, the application must assume that the value might potentially be updated before it has a chance to update it. This almost aways the case with read-only caches, and the solution is the traditional optimistic transaction pattern, which requires the application to explicitly state what assumptions it made about the old value of the cache entry. If the application doesn't want to bother stating those assumptions, it is free to lock the cache entry prior to reading it, ensuring that no other threads will mutate the entry, a pessimistic approach. The optimistic approach relies on what is sometimes called a "fuzzy read". In other words, the application assumes that the read should be correct, but it also acknowledges that it might not be. (I use the qualifier "sometimes" because in some writings, "fuzzy read" indicates the situation where the application actually sees an original value and then later sees an updated value within the same transaction -- however, both definitions are roughly equivalent from an application design perspective). If the read is not correct it is called a "stale read". Going back to the definition of concurrency, it may seem difficult to precisely define a stale read, but the practical way of detecting a stale read is that is will cause the encompassing transaction to roll back if it tries to update that value. The pessimistic approach relies on a "coherent read", a guarantee that the value returned is not only the same as the primary copy of that value, but also that it will remain that way. In most cases this can be used interchangeably with "repeatable read" (though that term has additional implications when used in the context of a database system). In none of cases above is it possible for the application to perform a "dirty read". A dirty read occurs when the application reads a piece of data that was never committed. In practice the only way this can occur is with multi-phase updates such as transactions, where a value may be temporarily update but then withdrawn when a transaction is rolled back. If another thread sees that value prior to the rollback, it is a dirty read. If an application uses optimistic transactions, dirty reads will merely result in a lack of forward progress (this is actually one of the main risks of dirty reads -- they can be chained and potentially cause cascading rollbacks). The concepts of dirty reads, fuzzy reads, stale reads and coherent reads are able to describe the vast majority of requirements that we see in the field. However, the important thing is to define the terms used to define requirements. A quick web search for each of the terms in this article will show multiple meanings, so I've selected what are generally the most common variations, but it never hurts to state each definition explicitly if they are critical to the success of a project (many applications have sufficiently loose requirements that precise terminology can be avoided).

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• The sign of a true manager is delegation (C# style)

  - by MarkPearl

  Today I thought I would write a bit about delegates in C#. Up till recently I have managed to side step any real understanding of what delegates do and why they are useful – I mean, I know roughly what they do and have used them a lot, but I have never really got down dirty with them and mucked about. Recently however with my renewed interest in Silverlight delegates came up again as a possible solution to a particular problem, and suddenly I found myself opening a bland little console application to just see exactly how far I could take delegates with my limited knowledge. So, let’s first look at the MSDN definition of delegates… A delegate declaration defines a reference type that can be used to encapsulate a method with a specific signature. A delegate instance encapsulates a static or an instance method. Delegates are roughly similar to function pointers in C++; however, delegates are type-safe and secure. Well, don’t you love MSDN for such a useful definition. I must give it credit though… later on it really explains it a bit better by saying “A delegate lets you pass a function as a parameter. The type safety of delegates requires the function you pass as a delegate to have the same signature as the delegate declaration.” A little more reading up on delegates mentions that delegates are similar to interfaces in that they enable the separation of specification and implementation. A delegate declares a single method, while an interface declares a group of methods. So enough reading - lets look at some code and see a basic example of a delegate… Let’s assume we have a console application with a simple delegate declared called AdjustValue like below… class Program { private delegate int AdjustValue(int val); static void Main(string[] args) { } } In a sense, all we have said is that we will be creating one or more methods that follow the same pattern as AdjustValue – i.e. they will take one input value of type int and return an integer. We could then expand our code to have various methods that match the structure of our delegate AdjustValue (remember the structure is int xxx (int xxx)) class Program { private delegate int AdjustValue(int val); private static int Dbl(int val) { return val * 2; } private static int AlwaysOne(int val) { return 1; } static void Main(string[] args) { } }  Above I have expanded my project to have two methods, one called Dbl and the other AlwaysOne. Dbl always returns double the input val and AlwaysOne always returns 1. I could now declare a variable and assign it to be one of those functions, like the following… class Program { private delegate int AdjustValue(int val); private static int Dbl(int val) { return val * 2; } private static int AlwaysOne(int val) { return 1; } static void Main(string[] args) { AdjustValue myDelegate; myDelegate = Dbl; Console.WriteLine(myDelegate(1).ToString()); Console.ReadLine(); } } In this instance I have declared an instance of the AdjustValue delegate called myDelegate; I have then told myDelegate to point to the method Dbl, and then called myDelegate(1). What would the result be? Yes, in this instance it would be exactly the same as me calling the following code… static void Main(string[] args) { Console.WriteLine(Dbl(1).ToString()); Console.ReadLine(); }   So why all the extra work for delegates when we could just do what we did above and call the method directly? Well… that separation of specification to implementation comes to mind. So, this all seems pretty simple. Let’s take a slightly more complicated variation to the console application. Assume that my project is the same as the one previously except that my main method is adjusted as follows… static void Main(string[] args) { AdjustValue myDelegate; myDelegate = Dbl; myDelegate = AlwaysOne; Console.WriteLine(myDelegate(1).ToString()); Console.ReadLine(); } What would happen in this scenario? Quite simply “1” would be written to the console, the reason being that myDelegate was last pointing to the AlwaysOne method before it was called. Make sense? In a way, the myDelegate is a variable method that can be swapped and changed when needed. Let’s make the code a little more confusing by using a delegate in the declaration of another delegate as shown below… class Program { private delegate int AdjustValue(InputValue val); private delegate int InputValue(); private static int Dbl(InputValue val) { return val()*2; } private static int GetInputVal() { Console.WriteLine("Enter a whole number : "); return Convert.ToInt32(Console.ReadLine()); } static void Main(string[] args) { AdjustValue myDelegate; myDelegate = Dbl; Console.WriteLine(myDelegate(GetInputVal).ToString()); Console.ReadLine(); } }   Now it gets really interesting because it looks like we have passed a method into a function in the main method by declaring… Console.WriteLine(myDelegate(GetInputVal).ToString()); So, what it the output? Well, try take a guess on what will happen – then copy the code and see if you got it right. Well that brings me to the end of this short explanation of Delegates. Hopefully it made sense!

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• Collaborative Whiteboard using WebSocket in GlassFish 4 - Text/JSON and Binary/ArrayBuffer Data Transfer (TOTD #189)

  - by arungupta

  This blog has published a few blogs on using JSR 356 Reference Implementation (Tyrus) as its integrated in GlassFish 4 promoted builds. TOTD #183: Getting Started with WebSocket in GlassFish TOTD #184: Logging WebSocket Frames using Chrome Developer Tools, Net-internals and Wireshark TOTD #185: Processing Text and Binary (Blob, ArrayBuffer, ArrayBufferView) Payload in WebSocket TOTD #186: Custom Text and Binary Payloads using WebSocket One of the typical usecase for WebSocket is online collaborative games. This Tip Of The Day (TOTD) explains a sample that can be used to build such games easily. The application is a collaborative whiteboard where different shapes can be drawn in multiple colors. The shapes drawn on one browser are automatically drawn on all other peer browsers that are connected to the same endpoint. The shape, color, and coordinates of the image are transfered using a JSON structure. A browser may opt-out of sharing the figures. Alternatively any browser can send a snapshot of their existing whiteboard to all other browsers. Take a look at this video to understand how the application work and the underlying code. The complete sample code can be downloaded here. The code behind the application is also explained below. The web page (index.jsp) has a HTML5 Canvas as shown: <canvas id="myCanvas" width="150" height="150" style="border:1px solid #000000;"></canvas> And some radio buttons to choose the color and shape. By default, the shape, color, and coordinates of any figure drawn on the canvas are put in a JSON structure and sent as a message to the WebSocket endpoint. The JSON structure looks like: { "shape": "square", "color": "#FF0000", "coords": { "x": 31.59999942779541, "y": 49.91999053955078 }} The endpoint definition looks like: @WebSocketEndpoint(value = "websocket",encoders = {FigureDecoderEncoder.class},decoders = {FigureDecoderEncoder.class})public class Whiteboard { As you can see, the endpoint has decoder and encoder registered that decodes JSON to a Figure (a POJO class) and vice versa respectively. The decode method looks like: public Figure decode(String string) throws DecodeException { try { JSONObject jsonObject = new JSONObject(string); return new Figure(jsonObject); } catch (JSONException ex) { throw new DecodeException("Error parsing JSON", ex.getMessage(), ex.fillInStackTrace()); }} And the encode method looks like: public String encode(Figure figure) throws EncodeException { return figure.getJson().toString();} FigureDecoderEncoder implements both decoder and encoder functionality but thats purely for convenience. But the recommended design pattern is to keep them in separate classes. In certain cases, you may even need only one of them. On the client-side, the Canvas is initialized as: var canvas = document.getElementById("myCanvas");var context = canvas.getContext("2d");canvas.addEventListener("click", defineImage, false); The defineImage method constructs the JSON structure as shown above and sends it to the endpoint using websocket.send(). An instant snapshot of the canvas is sent using binary transfer with WebSocket. The WebSocket is initialized as: var wsUri = "ws://localhost:8080/whiteboard/websocket";var websocket = new WebSocket(wsUri);websocket.binaryType = "arraybuffer"; The important part is to set the binaryType property of WebSocket to arraybuffer. This ensures that any binary transfers using WebSocket are done using ArrayBuffer as the default type seem to be blob. The actual binary data transfer is done using the following: var image = context.getImageData(0, 0, canvas.width, canvas.height);var buffer = new ArrayBuffer(image.data.length);var bytes = new Uint8Array(buffer);for (var i=0; i<bytes.length; i++) { bytes[i] = image.data[i];}websocket.send(bytes); This comprehensive sample shows the following features of JSR 356 API: Annotation-driven endpoints Send/receive text and binary payload in WebSocket Encoders/decoders for custom text payload In addition, it also shows how images can be captured and drawn using HTML5 Canvas in a JSP. How could this be turned in to an online game ? Imagine drawing a Tic-tac-toe board on the canvas with two players playing and others watching. Then you can build access rights and controls within the application itself. Instead of sending a snapshot of the canvas on demand, a new peer joining the game could be automatically transferred the current state as well. Do you want to build this game ? I built a similar game a few years ago. Do somebody want to rewrite the game using WebSocket APIs ? :-) Many thanks to Jitu and Akshay for helping through the WebSocket internals! Here are some references for you: JSR 356: Java API for WebSocket - Specification (Early Draft) and Implementation (already integrated in GlassFish 4 promoted builds) Subsequent blogs will discuss the following topics (not necessary in that order) ... Error handling Interface-driven WebSocket endpoint Java client API Client and Server configuration Security Subprotocols Extensions Other topics from the API

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• How can I implement a database TableView like thing in C++?

  - by Industrial-antidepressant

  How can I implement a TableView like thing in C++? I want to emulating a tiny relation database like thing in C++. I have data tables, and I want to transform it somehow, so I need a TableView like class. I want filtering, sorting, freely add and remove items and transforming (ex. view as UPPERCASE and so on). The whole thing is inside a GUI application, so datatables and views are attached to a GUI (or HTML or something). So how can I identify an item in the view? How can I signal it when the table is changed? Is there some design pattern for this? Here is a simple table, and a simple data item: #include <string> #include <boost/multi_index_container.hpp> #include <boost/multi_index/member.hpp> #include <boost/multi_index/ordered_index.hpp> #include <boost/multi_index/random_access_index.hpp> using boost::multi_index_container; using namespace boost::multi_index; struct Data { Data() {} int id; std::string name; }; struct row{}; struct id{}; struct name{}; typedef boost::multi_index_container< Data, indexed_by< random_access<tag<row> >, ordered_unique<tag<id>, member<Data, int, &Data::id> >, ordered_unique<tag<name>, member<Data, std::string, &Data::name> > > > TDataTable; class DataTable { public: typedef Data item_type; typedef TDataTable::value_type value_type; typedef TDataTable::const_reference const_reference; typedef TDataTable::index<row>::type TRowIndex; typedef TDataTable::index<id>::type TIdIndex; typedef TDataTable::index<name>::type TNameIndex; typedef TRowIndex::iterator iterator; DataTable() : row_index(rule_table.get<row>()), id_index(rule_table.get<id>()), name_index(rule_table.get<name>()), row_index_writeable(rule_table.get<row>()) { } TDataTable::const_reference operator[](TDataTable::size_type n) const { return rule_table[n]; } std::pair<iterator,bool> push_back(const value_type& x) { return row_index_writeable.push_back(x); } iterator erase(iterator position) { return row_index_writeable.erase(position); } bool replace(iterator position,const value_type& x) { return row_index_writeable.replace(position, x); } template<typename InputIterator> void rearrange(InputIterator first) { return row_index_writeable.rearrange(first); } void print_table() const; unsigned size() const { return row_index.size(); } TDataTable rule_table; const TRowIndex& row_index; const TIdIndex& id_index; const TNameIndex& name_index; private: TRowIndex& row_index_writeable; }; class DataTableView { DataTableView(const DataTable& source_table) {} // How can I implement this? // I want filtering, sorting, signaling upper GUI layer, and sorting, and ... }; int main() { Data data1; data1.id = 1; data1.name = "name1"; Data data2; data2.id = 2; data2.name = "name2"; DataTable table; table.push_back(data1); DataTable::iterator it1 = table.row_index.iterator_to(table[0]); table.erase(it1); table.push_back(data1); Data new_data(table[0]); new_data.name = "new_name"; table.replace(table.row_index.iterator_to(table[0]), new_data); for (unsigned i = 0; i < table.size(); ++i) std::cout << table[i].name << std::endl; #if 0 // using scenarios: DataTableView table_view(table); table_view.fill_from_source(); // synchronization with source table_view.remove(data_item1); // remove item from view table_view.add(data_item2); // add item from source table table_view.filter(filterfunc); // filtering table_view.sort(sortfunc); // sorting // modifying from source_able, hot to signal the table_view? // FYI: Table view is atteched to a GUI item table.erase(data); table.replace(data); #endif return 0; }

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• How do I dig myself out of this DEEP hole? [closed]

  - by user74847

  I may be a bit bias in the way i word this but any opinions and suggestions are welcome. I should start by saying i have a MSc in CS and a degree in new media +6 years expereince and im probably around a middleweight developer. I started a web development company with my friend from uni a year ago, there was a 4 month gap in the middle where i went miles away work on a big project. Ive since returned and picked up where we left off. A year on though i find im still staying up til 5am and getting up at 9 sometimes 2-3 days without sleep. While i was away i was working 9-5 and struggling to keep up with doing stuff for my clients 8 hours ahead, after work, so things stagnated. We currently have about 12 active projects, with one other part time developer and a full time freelancer who is dealing with one of our major projects. I am solely responsible for concurrently developing 2 big sites similar to gumtree in functionality, at the same time as about 5-6+ small WordPress based 5-10page sites. a lot of the content isnt in yet or the client is delaying so i chop and change project every other day which does my head in. Is it reasonable to expect myself to remember the intricate details of each project when i come back to it a week later? and remember the details of a task which hasnt been written down? my business partner seems to think so. or am i just forgetful? Im particularly bad at estimating timescales which doesnt help, added to that a lot of the technologies im am using are new to me (a magento site took weeks to theme rather than days and was full of bugs, even after 1000's of google searches and hours reading forums) im still trying to learn and find the best CMS for us to use and getting my head around the likes of Bootstrap and jquery, Cpanel / Linux (we just got a blank vps for me to set up with no experience) even installing an SSL certificate caused everyone's mail clients to go down which was more stress for me to sort out. I find the pressure of the workload and timescales and trying to learn this stuff so fast is beginning to turn me against my career path. The fact that i never seem to get anything done really winds up my business partner and iv come to associate him with the stress and pain of the whole situation especially when I get berated or a look that says "oh you retard" when I forget something. Even today i spent hours learning how a particular themeforest theme worked with wordpress and how i could twist it to work for our partiuclar needs, on the surface had done no work, that triggered a 30 minute tirade of anger and stress and questioning what i had done from my business partner. had i taken too long to work on that? shoudl i have done it in 2 hours instead of 6? i told him i would take 2 hours. i was wrong. I feel like im running myself into the ground. My sleeping pattern has got so bad that when im working im half asleep and making mistakes, my eyes are constantly purple underneath, i literally fall asleep at my desk, its affecting my social life too, ive not slept more than lightly for the last year and grind through impossible code puzzles in my half sleep wich keeps me awake, when im already exhausted. plus the work is rushed and buggy when it does get done so drags on into the next project. I also procrastinate quite badly, pacing the livingroom, looking out the window when Im alone for three days straight in the flat and start to get cabin fever which means i do even less work and the negative feedback loop continues. I get told im the only one with the problem when i say that i cant work from home any more, and examples of other freelancers get brought up. an office wouldnt bring any extra cash in to the company but im convinced having that moving more than 2 meters away from my bed to go to "work" would get me working, at the moment i feel guilty like i should be working 24-7. It is important that we do all this work to raise enough cash to get our business to the next level but every month still feels like a struggle to pay the rent (there is about £20K coming in by Jan) and i have to borrow money from friends often to buy food or get a taxi to a meeting, so it is vital the money keeps coming in. (im also 20 mins late for nearly all meetings but thats a different issue) have you experienced anything similar? how can i deal with the issues ive raised? is it realistic to develop 10 sites at once? how can i improve my relationship with my business partner? do you struggle to work at home? how do you deal with that? i think if i dont get my life on track by feb i will seriously consider giving it all up, but that seems like such a waste. any ideas!!? i need help! Thanks.

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