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• How to Achieve OC4J RMI Load Balancing

  - by fip

  This is an old, Oracle SOA and OC4J 10G topic. In fact this is not even a SOA topic per se. Questions of RMI load balancing arise when you developed custom web applications accessing human tasks running off a remote SOA 10G cluster. Having returned from a customer who faced challenges with OC4J RMI load balancing, I felt there is still some confusions in the field how OC4J RMI load balancing work. Hence I decide to dust off an old tech note that I wrote a few years back and share it with the general public. Here is the tech note: Overview A typical use case in Oracle SOA is that you are building web based, custom human tasks UI that will interact with the task services housed in a remote BPEL 10G cluster. Or, in a more generic way, you are just building a web based application in Java that needs to interact with the EJBs in a remote OC4J cluster. In either case, you are talking to an OC4J cluster as RMI client. Then immediately you must ask yourself the following questions: 1. How do I make sure that the web application, as an RMI client, even distribute its load against all the nodes in the remote OC4J cluster? 2. How do I make sure that the web application, as an RMI client, is resilient to the node failures in the remote OC4J cluster, so that in the unlikely case when one of the remote OC4J nodes fail, my web application will continue to function? That is the topic of how to achieve load balancing with OC4J RMI client. Solutions You need to configure and code RMI load balancing in two places: 1. Provider URL can be specified with a comma separated list of URLs, so that the initial lookup will land to one of the available URLs. 2. Choose a proper value for the oracle.j2ee.rmi.loadBalance property, which, along side with the PROVIDER_URL property, is one of the JNDI properties passed to the JNDI lookup.(http://docs.oracle.com/cd/B31017_01/web.1013/b28958/rmi.htm#BABDGFBI) More details below: About the PROVIDER_URL The JNDI property java.name.provider.url's job is, when the client looks up for a new context at the very first time in the client session, to provide a list of RMI context The value of the JNDI property java.name.provider.url goes by the format of a single URL, or a comma separate list of URLs. A single URL. For example: opmn:ormi://host1:6003:oc4j_instance1/appName1 A comma separated list of multiple URLs. For examples:  opmn:ormi://host1:6003:oc4j_instanc1/appName, opmn:ormi://host2:6003:oc4j_instance1/appName, opmn:ormi://host3:6003:oc4j_instance1/appName When the client looks up for a new Context the very first time in the client session, it sends a query against the OPMN referenced by the provider URL. The OPMN host and port specifies the destination of such query, and the OC4J instance name and appName are actually the “where clause” of the query. When the PROVIDER URL reference a single OPMN server Let's consider the case when the provider url only reference a single OPMN server of the destination cluster. In this case, that single OPMN server receives the query and returns a list of the qualified Contexts from all OC4Js within the cluster, even though there is a single OPMN server in the provider URL. A context represent a particular starting point at a particular server for subsequent object lookup. For example, if the URL is opmn:ormi://host1:6003:oc4j_instance1/appName, then, OPMN will return the following contexts: appName on oc4j_instance1 on host1 appName on oc4j_instance1 on host2, appName on oc4j_instance1 on host3,  (provided that host1, host2, host3 are all in the same cluster) Please note that One OPMN will be sufficient to find the list of all contexts from the entire cluster that satisfy the JNDI lookup query. You can do an experiment by shutting down appName on host1, and observe that OPMN on host1 will still be able to return you appname on host2 and appName on host3. When the PROVIDER URL reference a comma separated list of multiple OPMN servers When the JNDI propery java.naming.provider.url references a comma separated list of multiple URLs, the lookup will return the exact same things as with the single OPMN server: a list of qualified Contexts from the cluster. The purpose of having multiple OPMN servers is to provide high availability in the initial context creation, such that if OPMN at host1 is unavailable, client will try the lookup via OPMN on host2, and so on. After the initial lookup returns and cache a list of contexts, the JNDI URL(s) are no longer used in the same client session. That explains why removing the 3rd URL from the list of JNDI URLs will not stop the client from getting the EJB on the 3rd server. About the oracle.j2ee.rmi.loadBalance Property After the client acquires the list of contexts, it will cache it at the client side as “list of available RMI contexts”.  This list includes all the servers in the destination cluster. This list will stay in the cache until the client session (JVM) ends. The RMI load balancing against the destination cluster is happening at the client side, as the client is switching between the members of the list. Whether and how often the client will fresh the Context from the list of Context is based on the value of the  oracle.j2ee.rmi.loadBalance. The documentation at http://docs.oracle.com/cd/B31017_01/web.1013/b28958/rmi.htm#BABDGFBI list all the available values for the oracle.j2ee.rmi.loadBalance. Value Description client If specified, the client interacts with the OC4J process that was initially chosen at the first lookup for the entire conversation. context Used for a Web client (servlet or JSP) that will access EJBs in a clustered OC4J environment. If specified, a new Context object for a randomly-selected OC4J instance will be returned each time InitialContext() is invoked. lookup Used for a standalone client that will access EJBs in a clustered OC4J environment. If specified, a new Context object for a randomly-selected OC4J instance will be created each time the client calls Context.lookup(). Please note the regardless of the setting of oracle.j2ee.rmi.loadBalance property, the “refresh” only occurs at the client. The client can only choose from the "list of available context" that was returned and cached from the very first lookup. That is, the client will merely get a new Context object from the “list of available RMI contexts” from the cache at the client side. The client will NOT go to the OPMN server again to get the list. That also implies that if you are adding a node to the server cluster AFTER the client’s initial lookup, the client would not know it because neither the server nor the client will initiate a refresh of the “list of available servers” to reflect the new node. About High Availability (i.e. Resilience Against Node Failure of Remote OC4J Cluster) What we have discussed above is about load balancing. Let's also discuss high availability. This is how the High Availability works in RMI: when the client use the context but get an exception such as socket is closed, it knows that the server referenced by that Context is problematic and will try to get another unused Context from the “list of available contexts”. Again, this list is the list that was returned and cached at the very first lookup in the entire client session.

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• The Shift: how Orchard painlessly shifted to document storage, and how it’ll affect you

  - by Bertrand Le Roy

  We’ve known it all along. The storage for Orchard content items would be much more efficient using a document database than a relational one. Orchard content items are composed of parts that serialize naturally into infoset kinds of documents. Storing them as relational data like we’ve done so far was unnatural and requires the data for a single item to span multiple tables, related through 1-1 relationships. This means lots of joins in queries, and a great potential for Select N+1 problems. Document databases, unfortunately, are still a tough sell in many places that prefer the more familiar relational model. Being able to x-copy Orchard to hosters has also been a basic constraint in the design of Orchard. Combine those with the necessity at the time to run in medium trust, and with license compatibility issues, and you’ll find yourself with very few reasonable choices. So we went, a little reluctantly, for relational SQL stores, with the dream of one day transitioning to document storage. We have played for a while with the idea of building our own document storage on top of SQL databases, and Sébastien implemented something more than decent along those lines, but we had a better way all along that we didn’t notice until recently… In Orchard, there are fields, which are named properties that you can add dynamically to a content part. Because they are so dynamic, we have been storing them as XML into a column on the main content item table. This infoset storage and its associated API are fairly generic, but were only used for fields. The breakthrough was when Sébastien realized how this existing storage could give us the advantages of document storage with minimal changes, while continuing to use relational databases as the substrate. public bool CommercialPrices { get { return this.Retrieve(p => p.CommercialPrices); } set { this.Store(p => p.CommercialPrices, value); } } This code is very compact and efficient because the API can infer from the expression what the type and name of the property are. It is then able to do the proper conversions for you. For this code to work in a content part, there is no need for a record at all. This is particularly nice for site settings: one query on one table and you get everything you need. This shows how the existing infoset solves the data storage problem, but you still need to query. Well, for those properties that need to be filtered and sorted on, you can still use the current record-based relational system. This of course continues to work. We do however provide APIs that make it trivial to store into both record properties and the infoset storage in one operation: public double Price { get { return Retrieve(r => r.Price); } set { Store(r => r.Price, value); } } This code looks strikingly similar to the non-record case above. The difference is that it will manage both the infoset and the record-based storages. The call to the Store method will send the data in both places, keeping them in sync. The call to the Retrieve method does something even cooler: if the property you’re looking for exists in the infoset, it will return it, but if it doesn’t, it will automatically look into the record for it. And if that wasn’t cool enough, it will take that value from the record and store it into the infoset for the next time it’s required. This means that your data will start automagically migrating to infoset storage just by virtue of using the code above instead of the usual: public double Price { get { return Record.Price; } set { Record.Price = value; } } As your users browse the site, it will get faster and faster as Select N+1 issues will optimize themselves away. If you preferred, you could still have explicit migration code, but it really shouldn’t be necessary most of the time. If you do already have code using QueryHints to mitigate Select N+1 issues, you might want to reconsider those, as with the new system, you’ll want to avoid joins that you don’t need for filtering or sorting, further optimizing your queries. There are some rare cases where the storage of the property must be handled differently. Check out this string[] property on SearchSettingsPart for example: public string[] SearchedFields { get { return (Retrieve<string>("SearchedFields") ?? "") .Split(new[] {',', ' '}, StringSplitOptions.RemoveEmptyEntries); } set { Store("SearchedFields", String.Join(", ", value)); } } The array of strings is transformed by the property accessors into and from a comma-separated list stored in a string. The Retrieve and Store overloads used in this case are lower-level versions that explicitly specify the type and name of the attribute to retrieve or store. You may be wondering what this means for code or operations that look directly at the database tables instead of going through the new infoset APIs. Even if there is a record, the infoset version of the property will win if it exists, so it is necessary to keep the infoset up-to-date. It’s not very complicated, but definitely something to keep in mind. Here is what a product record looks like in Nwazet.Commerce for example: And here is the same data in the infoset: The infoset is stored in Orchard_Framework_ContentItemRecord or Orchard_Framework_ContentItemVersionRecord, depending on whether the content type is versionable or not. A good way to find what you’re looking for is to inspect the record table first, as it’s usually easier to read, and then get the item record of the same id. Here is the detailed XML document for this product: <Data> <ProductPart Inventory="40" Price="18" Sku="pi-camera-box" OutOfStockMessage="" AllowBackOrder="false" Weight="0.2" Size="" ShippingCost="null" IsDigital="false" /> <ProductAttributesPart Attributes="" /> <AutoroutePart DisplayAlias="camera-box" /> <TitlePart Title="Nwazet Pi Camera Box" /> <BodyPart Text="[...]" /> <CommonPart CreatedUtc="2013-09-10T00:39:00Z" PublishedUtc="2013-09-14T01:07:47Z" /> </Data> The data is neatly organized under each part. It is easy to see how that document is all you need to know about that content item, all in one table. If you want to modify that data directly in the database, you should be careful to do it in both the record table and the infoset in the content item record. In this configuration, the record is now nothing more than an index, and will only be used for sorting and filtering. Of course, it’s perfectly fine to mix record-backed properties and record-less properties on the same part. It really depends what you think must be sorted and filtered on. In turn, this potentially simplifies migrations considerably. So here it is, the great shift of Orchard to document storage, something that Orchard has been designed for all along, and that we were able to implement with a satisfying and surprising economy of resources. Expect this code to make its way into the 1.8 version of Orchard when that’s available.

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• Is RTD Stateless or Stateful?

  - by [email protected]

  Yes.   A stateless service is one where each request is an independent transaction that can be processed by any of the servers in a cluster.  A stateful service is one where state is kept in a server's memory from transaction to transaction, thus necessitating the proper routing of requests to the right server. The main advantage of stateless systems is simplicity of design. The main advantage of stateful systems is performance. I'm often asked whether RTD is a stateless or stateful service, so I wanted to clarify this issue in depth so that RTD's architecture will be properly understood. The short answer is: "RTD can be configured as a stateless or stateful service." The performance difference between stateless and stateful systems can be very significant, and while in a call center implementation it may be reasonable to use a pure stateless configuration, a web implementation that produces thousands of requests per second is practically impossible with a stateless configuration. RTD's performance is orders of magnitude better than most competing systems. RTD was architected from the ground up to achieve this performance. Features like automatic and dynamic compression of prediction models, automatic translation of metadata to machine code, lack of interpreted languages, and separation of model building from decisioning contribute to achieving this performance level. Because  of this focus on performance we decided to have RTD's default configuration work in a stateful manner. By being stateful RTD requests are typically handled in a few milliseconds when repeated requests come to the same session. Now, those readers that have participated in implementations of RTD know that RTD's architecture is also focused on reducing Total Cost of Ownership (TCO) with features like automatic model building, automatic time windows, automatic maintenance of database tables, automatic evaluation of data mining models, automatic management of models partitioned by channel, geography, etcetera, and hot swapping of configurations. How do you reconcile the need for a low TCO and the need for performance? How do you get the performance of a stateful system with the simplicity of a stateless system? The answer is that you make the system behave like a stateless system to the exterior, but you let it automatically take advantage of situations where being stateful is better. For example, one of the advantages of stateless systems is that you can route a message to any server in a cluster, without worrying about sending it to the same server that was handling the session in previous messages. With an RTD stateful configuration you can still route the message to any server in the cluster, so from the point of view of the configuration of other systems, it is the same as a stateless service. The difference though comes in performance, because if the message arrives to the right server, RTD can serve it without any external access to the session's state, thus tremendously reducing processing time. In typical implementations it is not rare to have high percentages of messages routed directly to the right server, while those that are not, are easily handled by forwarding the messages to the right server. This architecture usually provides the best of both worlds with performance and simplicity of configuration.   Configuring RTD as a pure stateless service A pure stateless configuration requires session data to be persisted at the end of handling each and every message and reloading that data at the beginning of handling any new message. This is of course, the root of the inefficiency of these configurations. This is also the reason why many "stateless" implementations actually do keep state to take advantage of a request coming back to the same server. Nevertheless, if the implementation requires a pure stateless decision service, this is easy to configure in RTD. The way to do it is: Mark every Integration Point to Close the session at the end of processing the message In the Session entity persist the session data on closing the session In the session entity check if a persisted version exists and load it An excellent solution for persisting the session data is Oracle Coherence, which provides a high performance, distributed cache that minimizes the performance impact of persisting and reloading the session. Alternatively, the session can be persisted to a local database. An interesting feature of the RTD stateless configuration is that it can cope with serializing concurrent requests for the same session. For example, if a web page produces two requests to the decision service, these requests could come concurrently to the decision services and be handled by different servers. Most stateless implementation would have the two requests step onto each other when saving the state, or fail one of the messages. When properly configured, RTD will make one message wait for the other before processing.   A Word on Context Using the context of a customer interaction typically significantly increases lift. For example, offer success in a call center could double if the context of the call is taken into account. For this reason, it is important to utilize the contextual information in decision making. To make the contextual information available throughout a session it needs to be persisted. When there is a well defined owner for the information then there is no problem because in case of a session restart, the information can be easily retrieved. If there is no official owner of the information, then RTD can be configured to persist this information.   Once again, RTD provides flexibility to ensure high performance when it is adequate to allow for some loss of state in the rare cases of server failure. For example, in a heavy use web site that serves 1000 pages per second the navigation history may be stored in the in memory session. In such sites it is typical that there is no OLTP that stores all the navigation events, therefore if an RTD server were to fail, it would be possible for the navigation to that point to be lost (note that a new session would be immediately established in one of the other servers). In most cases the loss of this navigation information would be acceptable as it would happen rarely. If it is desired to save this information, RTD would persist it every time the visitor navigates to a new page. Note that this practice is preferred whether RTD is configured in a stateless or stateful manner.  

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• Service Broker, not ETL

  - by jamiet

  I have been very quiet on this blog of late and one reason for that is I have been very busy on a client project that I would like to talk about a little here. The client that I have been working for has a website that runs on a distributed architecture utilising a messaging infrastructure for communication between different endpoints. My brief was to build a system that could consume these messages and produce analytical information in near-real-time. More specifically I basically had to deliver a data warehouse however it was the real-time aspect of the project that really intrigued me. This real-time requirement meant that using an Extract transformation, Load (ETL) tool was out of the question and so I had no choice but to write T-SQL code (i.e. stored-procedures) to process the incoming messages and load the data into the data warehouse. This concerned me though – I had no way to control the rate at which data would arrive into the system yet we were going to have end-users querying the system at the same time that those messages were arriving; the potential for contention in such a scenario was pretty high and and was something I wanted to minimise as much as possible. Moreover I did not want the processing of data inside the data warehouse to have any impact on the customer-facing website. As you have probably guessed from the title of this blog post this is where Service Broker stepped in! For those that have not heard of it Service Broker is a queuing technology that has been built into SQL Server since SQL Server 2005. It provides a number of features however the one that was of interest to me was the fact that it facilitates asynchronous data processing which, in layman’s terms, means the ability to process some data without requiring the system that supplied the data having to wait for the response. That was a crucial feature because on this project the customer-facing website (in effect an OLTP system) would be calling one of our stored procedures with each message – we did not want to cause the OLTP system to wait on us every time we processed one of those messages. This asynchronous nature also helps to alleviate the contention problem because the asynchronous processing activity is handled just like any other task in the database engine and hence can wait on another task (such as an end-user query). Service Broker it was then! The stored procedure called by the OLTP system would simply put the message onto a queue and we would use a feature called activation to pick each message off the queue in turn and process it into the warehouse. At the time of writing the system is not yet up to full capacity but so far everything seems to be working OK (touch wood) and crucially our users are seeing data in near-real-time. By near-real-time I am talking about latencies of a few minutes at most and to someone like me who is used to building systems that have overnight latencies that is a huge step forward! So then, am I advocating that you all go out and dump your ETL tools? Of course not, no! What this project has taught me though is that in certain scenarios there may be better ways to implement a data warehouse system then the traditional “load data in overnight” approach that we are all used to. Moreover I have really enjoyed getting to grips with a new technology and even if you don’t want to use Service Broker you might want to consider asynchronous messaging architectures for your BI/data warehousing solutions in the future. This has been a very high level overview of my use of Service Broker and I have deliberately left out much of the minutiae of what has been a very challenging implementation. Nonetheless I hope I have caused you to reflect upon your own approaches to BI and question whether other approaches may be more tenable. All comments and questions gratefully received! Lastly, if you have never used Service Broker before and want to kick the tyres I have provided below a very simple “Service Broker Hello World” script that will create all of the objects required to facilitate Service Broker communications and then send the message “Hello World” from one place to anther! This doesn’t represent a “proper” implementation per se because it doesn’t close down down conversation objects (which you should always do in a real-world scenario) but its enough to demonstrate the capabilities! @Jamiet ----------------------------------------------------------------------------------------------- /*This is a basic Service Broker Hello World app. Have fun! -Jamie */ USE MASTER GO CREATE DATABASE SBTest GO --Turn Service Broker on! ALTER DATABASE SBTest SET ENABLE_BROKER GO USE SBTest GO -- 1) we need to create a message type. Note that our message type is -- very simple and allowed any type of content CREATE MESSAGE TYPE HelloMessage VALIDATION = NONE GO -- 2) Once the message type has been created, we need to create a contract -- that specifies who can send what types of messages CREATE CONTRACT HelloContract (HelloMessage SENT BY INITIATOR) GO --We can query the metadata of the objects we just created SELECT * FROM   sys.service_message_types WHERE name = 'HelloMessage'; SELECT * FROM   sys.service_contracts WHERE name = 'HelloContract'; SELECT * FROM   sys.service_contract_message_usages WHERE  service_contract_id IN (SELECT service_contract_id FROM sys.service_contracts WHERE name = 'HelloContract') AND        message_type_id IN (SELECT message_type_id FROM sys.service_message_types WHERE name = 'HelloMessage'); -- 3) The communication is between two endpoints. Thus, we need two queues to -- hold messages CREATE QUEUE SenderQueue CREATE QUEUE ReceiverQueue GO --more querying metatda SELECT * FROM sys.service_queues WHERE name IN ('SenderQueue','ReceiverQueue'); --we can also select from the queues as if they were tables SELECT * FROM SenderQueue   SELECT * FROM ReceiverQueue   -- 4) Create the required services and bind them to be above created queues CREATE SERVICE Sender   ON QUEUE SenderQueue CREATE SERVICE Receiver   ON QUEUE ReceiverQueue (HelloContract) GO --more querying metadata SELECT * FROM sys.services WHERE name IN ('Receiver','Sender'); -- 5) At this point, we can begin the conversation between the two services by -- sending messages DECLARE @conversationHandle UNIQUEIDENTIFIER DECLARE @message NVARCHAR(100) BEGIN   BEGIN TRANSACTION;   BEGIN DIALOG @conversationHandle         FROM SERVICE Sender         TO SERVICE 'Receiver'         ON CONTRACT HelloContract WITH ENCRYPTION=OFF   -- Send a message on the conversation   SET @message = N'Hello, World';   SEND  ON CONVERSATION @conversationHandle         MESSAGE TYPE HelloMessage (@message)   COMMIT TRANSACTION END GO --check contents of queues SELECT * FROM SenderQueue   SELECT * FROM ReceiverQueue   GO -- Receive a message from the queue RECEIVE CONVERT(NVARCHAR(MAX), message_body) AS MESSAGE FROM ReceiverQueue GO --If no messages were received and/or you can't see anything on the queues you may wish to check the following for clues: SELECT * FROM sys.transmission_queue -- Cleanup DROP SERVICE Sender DROP SERVICE Receiver DROP QUEUE SenderQueue DROP QUEUE ReceiverQueue DROP CONTRACT HelloContract DROP MESSAGE TYPE HelloMessage GO USE MASTER GO DROP DATABASE SBTest GO

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• Big Data Matters with ODI12c

  - by Madhu Nair

  contributed by Mike Eisterer On October 17th, 2013, Oracle announced the release of Oracle Data Integrator 12c (ODI12c).  This release signifies improvements to Oracle’s Data Integration portfolio of solutions, particularly Big Data integration. Why Big Data = Big Business Organizations are gaining greater insights and actionability through increased storage, processing and analytical benefits offered by Big Data solutions.  New technologies and frameworks like HDFS, NoSQL, Hive and MapReduce support these benefits now. As further data is collected, analytical requirements increase and the complexity of managing transformations and aggregations of data compounds and organizations are in need for scalable Data Integration solutions. ODI12c provides enterprise solutions for the movement, translation and transformation of information and data heterogeneously and in Big Data Environments through: The ability for existing ODI and SQL developers to leverage new Big Data technologies. A metadata focused approach for cataloging, defining and reusing Big Data technologies, mappings and process executions. Integration between many heterogeneous environments and technologies such as HDFS and Hive. Generation of Hive Query Language. Working with Big Data using Knowledge Modules  ODI12c provides developers with the ability to define sources and targets and visually develop mappings to effect the movement and transformation of data.  As the mappings are created, ODI12c leverages a rich library of prebuilt integrations, known as Knowledge Modules (KMs).  These KMs are contextual to the technologies and platforms to be integrated.  Steps and actions needed to manage the data integration are pre-built and configured within the KMs.  The Oracle Data Integrator Application Adapter for Hadoop provides a series of KMs, specifically designed to integrate with Big Data Technologies.  The Big Data KMs include: Check Knowledge Module Reverse Engineer Knowledge Module Hive Transform Knowledge Module Hive Control Append Knowledge Module File to Hive (LOAD DATA) Knowledge Module File-Hive to Oracle (OLH-OSCH) Knowledge Module  Nothing to beat an Example: To demonstrate the use of the KMs which are part of the ODI Application Adapter for Hadoop, a mapping may be defined to move data between files and Hive targets.  The mapping is defined by dragging the source and target into the mapping, performing the attribute (column) mapping (see Figure 1) and then selecting the KM which will govern the process.  In this mapping example, movie data is being moved from an HDFS source into a Hive table.  Some of the attributes, such as “CUSTID to custid”, have been mapped over. Figure 1  Defining the Mapping Before the proper KM can be assigned to define the technology for the mapping, it needs to be added to the ODI project.  The Big Data KMs have been made available to the project through the KM import process.   Generally, this is done prior to defining the mapping. Figure 2  Importing the Big Data Knowledge Modules Following the import, the KMs are available in the Designer Navigator. v\:* {behavior:url(#default#VML);} o\:* {behavior:url(#default#VML);} w\:* {behavior:url(#default#VML);} .shape {behavior:url(#default#VML);} Normal 0 false false false EN-US ZH-TW X-NONE MicrosoftInternetExplorer4 /* 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:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:10.0pt; font-family:"Calibri","sans-serif"; mso-bidi-font-family:"Times New Roman";} Figure 3  The Project View in Designer, Showing Installed IKMs Once the KM is imported, it may be assigned to the mapping target.  This is done by selecting the Physical View of the mapping and examining the Properties of the Target.  In this case MOVIAPP_LOG_STAGE is the target of our mapping. Figure 4  Physical View of the Mapping and Assigning the Big Data Knowledge Module to the Target Alternative KMs may have been selected as well, providing flexibility and abstracting the logical mapping from the physical implementation.  Our mapping may be applied to other technologies as well. The mapping is now complete and is ready to run.  We will see more in a future blog about running a mapping to load Hive. To complete the quick ODI for Big Data Overview, let us take a closer look at what the IKM File to Hive is doing for us.  ODI provides differentiated capabilities by defining the process and steps which normally would have to be manually developed, tested and implemented into the KM.  As shown in figure 5, the KM is preparing the Hive session, managing the Hive tables, performing the initial load from HDFS and then performing the insert into Hive.  HDFS and Hive options are selected graphically, as shown in the properties in Figure 4. Figure 5  Process and Steps Managed by the KM What’s Next Big Data being the shape shifting business challenge it is is fast evolving into the deciding factor between market leaders and others. Now that an introduction to ODI and Big Data has been provided, look for additional blogs coming soon using the Knowledge Modules which make up the Oracle Data Integrator Application Adapter for Hadoop: Importing Big Data Metadata into ODI, Testing Data Stores and Loading Hive Targets Generating Transformations using Hive Query language Loading Oracle from Hadoop Sources For more information now, please visit the Oracle Data Integrator Application Adapter for Hadoop web site, http://www.oracle.com/us/products/middleware/data-integration/hadoop/overview/index.html Do not forget to tune in to the ODI12c Executive Launch webcast on the 12th to hear more about ODI12c and GG12c. Normal 0 false false false EN-US ZH-TW X-NONE MicrosoftInternetExplorer4 /* 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:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:10.0pt; font-family:"Calibri","sans-serif"; mso-bidi-font-family:"Times New Roman";}

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• class hierarchy design for small java project

  - by user523956

  I have written a java code which does following:- Main goal is to fetch emails from (inbox, spam) folders and store them in database. It fetches emails from gmail,gmx,web.de,yahoo and Hotmail. Following attributes are stored in mysql database. Slno, messagedigest, messageid, foldername, dateandtime, receiver, sender, subject, cc, size and emlfile. For gmail,gmy and web.de, I have used javamail API, because email form it can be fetched with IMAP. For yahoo and hotmail, I have used html parser and httpclient to fetch emails form spam folder and for inbox folder, I have used pop3 javamail API. I want to have proper class hierarchy which makes my code efficient and easily reusable. As of now I have designed class hierarchy as below: I am sure it can still be improved. So I would like to have different opinions on it. I have following classes and methods as of now. MainController:- Here I pass emailid, password and foldername from which emails have to be fetched. Abstract Class :-EmailProtocol Abstract Methods of it (All methods except executeParser contains method definition):- connectImap() // used by gmx,gmail and web.de email ids connectPop3() // used by hotmail and yahoo to fetch emails of inbox folder createMessageDigest // used by every email provider(gmx, gmail,web.de,yahoo,hotmail) establishDBConnection // used by every email emailAlreadyExists // used by every email which checks whether email already exists in db or not, if not then store it. storeemailproperties // used by every email to store emails properties to mysql database executeParser // nothing written in it. Overwridden and used by just hotmail and yahoo to fetch emails form spam folder. Imap extends EmailProtocol (nothing in it. But I have to have it to access methods of EmailProtocol. This is used to fetch emails from gmail,gmx and web.de) I know this is really a bad way but don't know how to do it other way. Hotmsil extends EmailProtocol Methods:- executeParser() :- This is used by just hotmail email id. fetchjunkemails() :- This is also very specific for only hotmail email id. Yahoo extends EmailProtocol Methods:- executeParser() storeEmailtotemptable() MoveEmailtoInbox() getFoldername() nullorEquals() All above methods are specific for yahoo email id. public DateTimeFormat(class) format() //this formats datetime of gmax,gmail and web.de emails. formatYahoodate //this formats datetime of yahoo email. formatHotmaildate // this formats datetime of hotmail email. public StringFormat ConvertStreamToString() // Accessed by every class except DateTimeFormat class. formatFromTo() // Accessed by every class except DateTimeFormat class. public Class CheckDatabaseExistance public static void checkForDatabaseTablesAvailability() (This method checks at the beginnning whether database and required tables exist in mysql or not. if not it creates them) Please see code of my MainController class so that You can have an idea about how I use different classes. public class MainController { public static void main(String[] args) throws Exception { ArrayList<String> web_de_folders = new ArrayList<String>(); web_de_folders.add("INBOX"); web_de_folders.add("Unbekannt"); web_de_folders.add("Spam"); web_de_folders.add("OUTBOX"); web_de_folders.add("SENT"); web_de_folders.add("DRAFTS"); web_de_folders.add("TRASH"); web_de_folders.add("Trash"); ArrayList<String> gmx_folders = new ArrayList<String>(); gmx_folders.add("INBOX"); gmx_folders.add("Archiv"); gmx_folders.add("Entwürfe"); gmx_folders.add("Gelöscht"); gmx_folders.add("Gesendet"); gmx_folders.add("Spamverdacht"); gmx_folders.add("Trash"); ArrayList<String> gmail_folders = new ArrayList<String>(); gmail_folders.add("Inbox"); gmail_folders.add("[Google Mail]/Spam"); gmail_folders.add("[Google Mail]/Trash"); gmail_folders.add("[Google Mail]/Sent Mail"); ArrayList<String> pop3_folders = new ArrayList<String>(); pop3_folders.add("INBOX"); CheckDatabaseExistance.checkForDatabaseTablesAvailability(); EmailProtocol imap = new Imap(); System.out.println("CHECKING FOR NEW EMAILS IN WEB.DE...(IMAP)"); System.out.println("*********************************************************************************"); imap.connectImap("[email protected]", "pwd", web_de_folders); System.out.println("\nCHECKING FOR NEW EMAILS IN GMX.DE...(IMAP)"); System.out.println("*********************************************************************************"); imap.connectImap("[email protected]", "pwd", gmx_folders); System.out.println("\nCHECKING FOR NEW EMAILS IN GMAIL...(IMAP)"); System.out.println("*********************************************************************************"); imap.connectImap("[email protected]", "pwd", gmail_folders); EmailProtocol yahoo = new Yahoo(); Yahoo y=new Yahoo(); System.out.println("\nEXECUTING YAHOO PARSER"); System.out.println("*********************************************************************************"); y.executeParser("http://de.mc1321.mail.yahoo.com/mc/welcome?ymv=0","[email protected]","pwd"); System.out.println("\nCHECKING FOR NEW EMAILS IN INBOX OF YAHOO (POP3)"); System.out.println("*********************************************************************************"); yahoo.connectPop3("[email protected]","pwd",pop3_folders); System.out.println("\nCHECKING FOR NEW EMAILS IN INBOX OF HOTMAIL (POP3)"); System.out.println("*********************************************************************************"); yahoo.connectPop3("[email protected]","pwd",pop3_folders); EmailProtocol hotmail = new Hotmail(); Hotmail h=new Hotmail(); System.out.println("\nEXECUTING HOTMAIL PARSER"); System.out.println("*********************************************************************************"); h.executeParser("https://login.live.com/ppsecure/post.srf","[email protected]","pwd"); } } I have kept DatetimeFormat and StringFormat class public so that I can access its public methods by just (DatetimeFormat.formatYahoodate for e.g. from different methods). This is the first time I have developed something in java. It serves its purpose but of course code is still not so efficient I think. I need your suggestions on this project.

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• Developing with Fluid UI – The Fluid Home Page

  - by Dave Bain

  v\:* {behavior:url(#default#VML);} o\:* {behavior:url(#default#VML);} w\:* {behavior:url(#default#VML);} .shape {behavior:url(#default#VML);} The first place to start with Fluid UI is with the Fluid Home Page. Sometimes it’s referred to as the landing page, but it’s formally called the Fluid Home Page. It’s delivered with PeopleTools 8.54, and the nice thing about it is, it’s a component. That’s one thing you’ll discover with Fluid UI. Fluid UI is built int PeopleTools with Fluid UI. The Home Page is a component, the tiles or grouplets are group boxes, and the search and prompt pages are just pages. It makes it easy to find things, customize and brand the applications (and of course to see what’s going on) when you can open it in AppDesigner. To see what makes a component fluid, let’s start with the Fluid Home Page. It’s a component called PT_LANDINGPAGE. You can open it in AppDesigner and see what’s unique and different about Fluid UI. If you open the Component Properties dialog, you’ll see a new tab called Fluid On the Component Properties Fluid tab you’ll see the most important checkbox of all, Fluid Mode. That is the one flag that will tell PeopleSoft if the component is Fluid (responsive, dynamic layout) or classic (pixel perfect). Now that you know it’s a single flag, you know that a component can’t be both Fluid UI and Classic at the same time, it’s one or the other. There are some other interesting fields on this page. The Small Form Factor Optimized field tells us whether or not to display this on a small device (think smarphone). Header Toolbar Actions offer standard options that are set at the component level so you have complete control of the components header bar. You’ll notice that the PT_LANDINGPAGE has got some PostBuild PeopleCode. That’s to build the grouplets that are used to launch Fluid UI Pages (more about those later). Probably not a good idea to mess with that code! The next thing to look at is the Page Definition for the PT_LANDINGPAGE component. When you open the page PT_LANDINGPAGE it will look different than anything you’ve ever seen. You’re probably thinking “What’s up with all the group boxes”? That is where Fluid UI is so different. In classic PeopleSoft, you put a button, field, group, any control on a page and that’s where it shows up, no questions asked. With Fluid UI, everything is positioned relative to something else. That’s why there are so many containers (you know them as group boxes). They are UI objects that are used for dynamic positioning. The Fluid Home Page has some special behavior and special settings. The first is in the Web Profile Configuration settings (Main Menu->PeopleTools->Web Profile->Web Profile Configuration from the main menu). There are two checkboxes that control the behavior of Fluid UI. Disable Fluid Mode and Disable Fluid On Desktop. Disable Fluid Mode prevents any Fluid UI component from being run from this installation. This is a web profile setting for users that want to run later versions of PeopleTools but only want to run Classic PeopleSoft pages. The second setting, Disable Fluid On Desktop allows the Fluid UI to be run on mobile devices such as smartphones and tablets, but prevents Fluid UI from running on a desktop computer. Fluid UI settings are also make in My Personalizations (Main Menu->My Personalizations from the Main Menu), in the General Options section. In that section, each user has the choice to determine the home page for their desktop and for tablets. Now that you know the Fluid UI landing page is just a component, and the profile and personalization settings, you should be able to launch one. It’s pretty easy to add a menu using Structure and Content, just make sure the proper security is set up. You’ll have to run a Fluid UI supported browser in order to see it. Latest versions of Chrome, Firefox and IE will do. Check the certification page on MOS for all the details. When you open the first Fluid Landing Page, there’s not much there. Not to worry, we’ll get some content on it soon. Take a moment to navigate around and look at some of the header actions that were set up from the component properties. The home button takes you back to the classic system. You won’t see any notifications and the personalization doesn’t have any content to add. The NavBar icon on the top right has a lot of content, including a Navigator and Classic home. Spend some time looking through what’s available. Stay tuned for more. Next up is adding some content. Normal 0 false 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:8.0pt; mso-para-margin-left:0in; line-height:107%; 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;}

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• CodePlex Daily Summary for Friday, August 22, 2014

  CodePlex Daily Summary for Friday, August 22, 2014Popular ReleasesQuickMon: Version 3.22: This release add two important changes. 1. Config variables at the monitor pack level (global to entire monitor pack for all Collectors) 2. The QuickMon (Windows) service now automatically reloads monitor packs that have been changed since it was started. This means you don't have to restart the service for changes to take effect.SSIS ReportGeneratorTask: ReportGenerator Task 1.8: New version of the SSIS Report Generator Task that supports SQL Server 2008, 2012 and 2014. In addition to minor bug fixes Multi-Value Parameters and Execution Information were integrated. The complete variable and parameter assignment is now a string and can be set dynamically.Corefig for Windows Server 2012 Core and Hyper-V Server 2012: Corefig 1.1.2 ISO: FixesUpdated Hyper-V scripts to use version 2 of the WMI tree. Updated the Hyper-V check for saved VM to look for the proper identifier. Fixed text issues with the licensing tab (thanks to briangw for rooting this problem out). EnhancementsNew (and improved) version number in Corefig.psd1.Outlook 2013 Backup Add-In: Outlook Backup Add-In 1.3: Changelog for new version: Added button in config-window to reset the last backup-time (this will trigger the backup after closing outlook) Minimum interval set to 0 (backup at each closing of outlook) Catch exception when data store entry is corrupt Added two parameters (prefix and suffix) to automatically rename the backup file Updated VSTO-Runtime to 10.0.50325 Upgraded project to Visual Studio 2013 Added optional command to run after backup (e.g. pack backup files, ...) Add...babelua: 1.6.7.0: V1.6.7.0 - 2014.8.21New feature: add a file search window ( ctrl+1 or ALT+L ), like The file search in VC Assistant; Stability improvement: performance improvement when BabeLua load/unload; performance improvement when debugger load lua files;File Explorer for WPF: FileExplorer3_20August2014: Please see Aug14 Update.Open NFe: RDI Open NFe 3.0 (alpha): Atualização para o layout 3.10 da NFe.ODBC Connect: v1.0: ODBC Connect executables for both 32bit and 64bit ODBC data sourcesMSSQL Deployment Tool: Microsoft SQL Deploy Tool v1.3.1: MicrosoftSqlDeployTool: v1.3.1.38348 What's changed? Update namespace and assembly name. Bug fixing.SharePoint 2013 Search Query Tool: SharePoint 2013 Search Query Tool v2.1: Layout improvements Bug fixes Stores auth method and user name Moved experimental settings to Advanced boxCtrlAltStudio Viewer: CtrlAltStudio Viewer 1.2.2.41183 Alpha: This alpha of the CtrlAltStudio Viewer provides some preliminary Oculus Rift DK2 support. For more details, see the release notes linked to below. Release notes: http://ctrlaltstudio.com/viewer/release-notes/1-2-2-41183-alpha Support info: http://ctrlaltstudio.com/viewer/support Privacy policy: http://ctrlaltstudio.com/viewer/privacy Disclaimer: This software is not provided or supported by Linden Lab, the makers of Second Life.HDD Guardian: HDD Guardian 0.6.1: New: package now include smartctl 6.3; Removed: standard notification e-mail. Now you have to set your mail server to send e-mail alerts; Bugfix: USB detection error; custom e-mail server settings issue; bottom panel displays a wrong ATA error count.VG-Ripper & PG-Ripper: VG-Ripper 2.9.62: changes NEW: Added Support for 'MadImage.org' links NEW: Added Support for 'ImgSpot.org' links NEW: Added Support for 'ImgClick.net' links NEW: Added Support for 'Imaaage.com' links NEW: Added Support for 'Image-Bugs.com' links NEW: Added Support for 'Pictomania.org' links NEW: Added Support for 'ImgDap.com' links NEW: Added Support for 'FileSpit.com' links FIXED: 'ImgSee.me' linksMagick.NET: Magick.NET 7.0.0.0001: Magick.NET linked with ImageMagick 7-Beta.CMake Tools for Visual Studio: CMake Tools for Visual Studio 1.2: This release adds the following new features and bug fixes from CMake Tools for Visual Studio 1.1: Added support for CMake 3.0. Added support for word completion. Added IntelliSense support for the CMAKEHOSTSYSTEM_INFORMATION command. Fixed syntax highlighting for tokens beginning with escape sequences. Fixed issue uninstalling CMake Tools for Visual Studio after Visual Studio has been uninstalled.GW2 Personal Assistant Overlay: GW2 Personal Assistant Overlay 1.1: Overview1.1 is the second 'stable' release of the GW2 Personal Assistant Overlay. This version includes just a couple of very minor features and some minor bug fixes. For details regarding installation, setup, and general use, see Documentation. Note: If you were using a previous version, you will probably want to copy over the following user settings files: GW2PAO.DungeonSettings.xml GW2PAO.EventSettings.xml GW2PAO.WvWSettings.xml GW2PAO.ZoneCompletionSettings.xml New FeaturesAdded new "No...Fluentx: Fluentx v1.5.3: Added few more extension methods.fastJSON: v2.1.2: 2.1.2 - bug fix circular referencesJPush.NET: JPush Server SDK 1.2.1 (For JPush V3): Assembly: 1.2.1.24728 JPush REST API Version: v3 JPush Documentation Reference .NET framework: v4.0 or above. Sample: class: JPushClientV3 2014 Augest 15th.SEToolbox: SEToolbox 01.043.008 Release 1: Changed ship/station names to use new DisplayName instead of Beacon/Antenna. Fixed issue with updated SE binaries 01.043.018 using new Voxel Material definitions.New Projects1thManage: GDT for erevery oneCreateProjectOnCodePlex: This is the first project for CoderCamps.HEAD FIRST C# LAB 1 : A DAY AT THE RACES: This has been provided for educational purposes and general discussion to improve coding practices associated with the resources detailed within Head First C#.Introduce Audit logging to your EF application using Repository & Unit of Work: Introduce Auditing in your application that uses Entity Framework by utilizing the Repository and Unit of Work design patterns.License Registration (C++): Allow to create demo version, activate or not a module.MS Word SharepointWiki Plugin: Scope of the Plugin is to enable a Post to a Sharepoint Wiki from within MS Word with Formatted Text and Images.Send My Zip: This app will help you to send the files were zipped then send the email about password information. This project is currently in setup mode and only availablewinhttp: this is a project for http/https download.Wix Builder: WixBuilder focusses on easily generating a WiX script from a project ouput, compile and link it into msi installer using the WiX Toolset.XiamiSig: ????????。

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• Big Visible Charts

  - by Robert May

  An important part of Agile is the concept of transparency and visibility. In proper functioning teams, stakeholders can look at any team at any time in the iteration or release and see how that team is doing by simply looking at what we call Big Visible Charts. If you’ve done Scrum, you’ve seen these charts. However, interpreting these charts can often be an art form. There are several different charts that can be useful. In this newsletter, I’ll focus on the Iteration Burndown and Cumulative Flow charts. I’ve included a copy of the spreadsheet that I used to create the charts, and if you don’t have a tool that creates them for you, you can use this spreadsheet to do so. Our preferred tool for managing Scrum projects is Rally. Rally creates all of these charts for you, saving you quite a bit of time. The Iteration Burndown and Cumulative Flow Charts This is the main chart that teams use. Although less useful to stakeholders, this chart is critical to the team and provides quite a bit of information to the team about how their iteration is going. Most charts are a combination of the charts below, so you may need to combine aspects of each section to understand what is happening in your iterations. Ideal Ah, isn’t that a pretty picture? Unfortunately, it’s also very unrealistic. I’ve seen iterations that come close to ideal, but never that match perfectly. If your iteration matches perfectly, chances are, someone is playing with the numbers. Reality is just too difficult to have a burndown chart that matches this exactly. Late Planning Iteration started, but the team didn’t. You can tell this by the fact that the real number of estimated hours didn’t appear until day two. In the cumulative flow, you can also see that nothing was defined in Day one and two. You want to avoid situations like this. You’ll note that the team had to burn faster than is ideal to meet the iteration because of the late planning. This often results in long weeks and days. Testing Starved Determining whether or not testing is starved is difficult without the cumulative flow. The pattern in the burndown could be nothing more that developers not completing stories early enough or could be caused by stories being too big. With the cumulative flow, however, you see that only small bites are in progress and stories were completed early, but testing didn’t start testing until the end of the iteration, and didn’t complete testing all stories in the iteration. When this happens, question whether or not your testing resources are sufficient for your team and whether or not acceptance is adequately defined. No Testing With this one, both graphs show the same thing; the team needs testers and testing! Without testing, what was completed cannot be verified to make sure that it is acceptable to the business. If you find yourself in this situation, review your testing practices and acceptance testing process and make changes today. Late Development With this situation, both graphs tell a story. In the top graph, you can see that the hours failed to burn down as quickly as the team expected. This could be caused by the team not correctly estimating their hours or the team could have had illness or some other issue that affected them. Often, when teams are tackling something that is more unknown, they’ll run into technical barriers that cause the burn down to happen slower than expected. In the cumulative flow graph, you can see that not much was completed in the first few days. This could be because of illness or technical barriers or simply poor estimation. Testing was able to keep up with everything that was completed, however. No Tool Updating When you see graphs that look like this, you can be assured that it’s because the team is not updating the tool that generates the graphs. Review your policy for when they are to update. On the teams that I run, I require that each team member updates the tool at least once daily. You should also check to see how well the team is breaking down stories into tasks. If they’re creating few large tasks, graphs can look similar to this. As a general rule, I never allow tasks, other than Unit Testing and Uncertainty, to be greater than eight hours in duration. Scope Increase I always encourage team members to enter in however much time they think they have left on a task, even if that means increasing the total amount of time left to do. You get a much better and more realistic picture this way. Increasing time remaining could explain the burndown graph, but by looking at the cumulative flow graph, we can see that stories were added to the iteration and scope was increased. Since planning should consume all of the hours in the iteration, this is almost always a bad thing. If the scope change happened late in the iteration and the hours remaining were well below the ideal burn, then increasing scope is probably o.k., but estimation needs to get better. However, with the charts above, that’s clearly not what happened and the team was required to do extra work to make the iteration. If you find this happening, your product owner and ScrumMasters need training. The team also needs to learn to say no. Scope Decrease Scope decreases are just as bad as scope increases. Usually, graphs above show that the team did a poor job of estimating their stories and part way through had to reduce scope to change the iteration. This will happen once in a while, but if you find it’s a pattern on your team, you need to re-evaluate planning. Some teams are hopelessly optimistic. In those cases, I’ll introduce a task I call “Uncertainty.” With Uncertainty, the team estimates how many hours they might need if things don’t go well with the tasks they’ve defined. They try to estimate things that could go poorly and increase the time appropriately. Having an Uncertainty task allows them to have a low and high estimate. Uncertainty should not just be an arbitrary buffer. It must correlate to real uncertainty in the tasks that have been defined. Stories are too Big Often, we see graphs like the ones above. Note that the burndown looks fairly good, other than the chunky acceptance of stories. However, when you look at cumulative flow, you can see that at one point, everything is in progress. This is a bad thing. When you see graphs like this, you’re in one of two states. You may just have a very small team and can only handle one or two stories in your iteration. If you have more than one or two people, then the most likely problem is that your stories are far too big. To combat this, break large high hour stories into smaller pieces that can be completed independently and accepted independently. If you don’t, you’ll likely be requiring your testers to do heroic things to complete testing on the last day of the iteration and you’re much more likely to have the entire iteration fail, because of the limited amount of things that can be completed. Summary There are other charts that can be useful when doing scrum. If you don’t have any big visible charts, you really need to evaluate your process and change. These charts can provide the team a wealth of information and help you write better software. If you have any questions about charts that you’re seeing on your team, contact me with a screen capture of the charts and I’ll tell you what I’m seeing in those charts. I always want this information to be useful, so please let me know if you have other questions. Technorati Tags: Agile

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• Network communications mechanisms for SQL Server

  - by Akshay Deep Lamba

  Problem I am trying to understand how SQL Server communicates on the network, because I'm having to tell my networking team what ports to open up on the firewall for an edge web server to communicate back to the SQL Server on the inside. What do I need to know? Solution In order to understand what needs to be opened where, let's first talk briefly about the two main protocols that are in common use today: TCP - Transmission Control Protocol UDP - User Datagram Protocol Both are part of the TCP/IP suite of protocols. We'll start with TCP. TCP TCP is the main protocol by which clients communicate with SQL Server. Actually, it is more correct to say that clients and SQL Server use Tabular Data Stream (TDS), but TDS actually sits on top of TCP and when we're talking about Windows and firewalls and other networking devices, that's the protocol that rules and controls are built around. So we'll just speak in terms of TCP. TCP is a connection-oriented protocol. What that means is that the two systems negotiate the connection and both agree to it. Think of it like a phone call. While one person initiates the phone call, the other person has to agree to take it and both people can end the phone call at any time. TCP is the same way. Both systems have to agree to the communications, but either side can end it at any time. In addition, there is functionality built into TCP to ensure that all communications can be disassembled and reassembled as necessary so it can pass over various network devices and be put together again properly in the right order. It also has mechanisms to handle and retransmit lost communications. Because of this functionality, TCP is the protocol used by many different network applications. The way the applications all can share is through the use of ports. When a service, like SQL Server, comes up on a system, it must listen on a port. For a default SQL Server instance, the default port is 1433. Clients connect to the port via the TCP protocol, the connection is negotiated and agreed to, and then the two sides can transfer information as needed until either side decides to end the communication. In actuality, both sides will have a port to use for the communications, but since the client's port is typically determined semi-randomly, when we're talking about firewalls and the like, typically we're interested in the port the server or service is using. UDP UDP, unlike TCP, is not connection oriented. A "client" can send a UDP communications to anyone it wants. There's nothing in place to negotiate a communications connection, there's nothing in the protocol itself to coordinate order of communications or anything like that. If that's needed, it's got to be handled by the application or by a protocol built on top of UDP being used by the application. If you think of TCP as a phone call, think of UDP as a postcard. I can put a postcard in the mail to anyone I want, and so long as it is addressed properly and has a stamp on it, the postal service will pick it up. Now, what happens it afterwards is not guaranteed. There's no mechanism for retransmission of lost communications. It's great for short communications that doesn't necessarily need an acknowledgement. Because multiple network applications could be communicating via UDP, it uses ports, just like TCP. The SQL Browser or the SQL Server Listener Service uses UDP. Network Communications - Talking to SQL Server When an instance of SQL Server is set up, what TCP port it listens on depends. A default instance will be set up to listen on port 1433. A named instance will be set to a random port chosen during installation. In addition, a named instance will be configured to allow it to change that port dynamically. What this means is that when a named instance starts up, if it finds something already using the port it normally uses, it'll pick a new port. If you have a named instance, and you have connections coming across a firewall, you're going to want to use SQL Server Configuration Manager to set a static port. This will allow the networking and security folks to configure their devices for maximum protection. While you can change the network port for a default instance of SQL Server, most people don't. Network Communications - Finding a SQL Server When just the name is specified for a client to connect to SQL Server, for instance, MySQLServer, this is an attempt to connect to the default instance. In this case the client will automatically attempt to communicate to port 1433 on MySQLServer. If you've switched the port for the default instance, you'll need to tell the client the proper port, usually by specifying the following syntax in the connection string: <server>,<port>. For instance, if you moved SQL Server to listen on 14330, you'd use MySQLServer,14330 instead of just MySQLServer. However, because a named instance sets up its port dynamically by default, the client never knows at the outset what the port is it should talk to. That's what the SQL Browser or the SQL Server Listener Service (SQL Server 2000) is for. In this case, the client sends a communication via the UDP protocol to port 1434. It asks, "Where is the named instance?" So if I was running a named instance called SQL2008R2, it would be asking the SQL Browser, "Hey, how do I talk to MySQLServer\SQL2008R2?" The SQL Browser would then send back a communications from UDP port 1434 back to the client telling the client how to talk to the named instance. Of course, you can skip all of this of you set that named instance's port statically. Then you can use the <server>,<port> mechanism to connect and the client won't try to talk to the SQL Browser service. It'll simply try to make the connection. So, for instance, is the SQL2008R2 instance was listening on port 20080, specifying MySQLServer,20080 would attempt a connection to the named instance. Network Communications - Named Pipes Named pipes is an older network library communications mechanism and it's generally not used any longer. It shouldn't be used across a firewall. However, if for some reason you need to connect to SQL Server with it, this protocol also sits on top of TCP. Named Pipes is actually used by the operating system and it has its own mechanism within the protocol to determine where to route communications. As far as network communications is concerned, it listens on TCP port 445. This is true whether we're talking about a default or named instance of SQL Server. The Summary Table To put all this together, here is what you need to know: Type of Communication Protocol Used Default Port Finding a SQL Server or SQL Server Named Instance UDP 1434 Communicating with a default instance of SQL Server TCP 1433 Communicating with a named instance of SQL Server TCP * Determined dynamically at start up Communicating with SQL Server via Named Pipes TCP 445

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• SQL University: What and why of database refactoring

  - by Mladen Prajdic

  This is a post for a great idea called SQL University started by Jorge Segarra also famously known as SqlChicken on Twitter. It’s a collection of blog posts on different database related topics contributed by several smart people all over the world. So this week is mine and we’ll be talking about database testing and refactoring. In 3 posts we’ll cover: SQLU part 1 - What and why of database testing SQLU part 2 - What and why of database refactoring SQLU part 3 - Tools of the trade This is a second part of the series and in it we’ll take a look at what database refactoring is and why do it. Why refactor a database To know why refactor we first have to know what refactoring actually is. Code refactoring is a process where we change module internals in a way that does not change that module’s input/output behavior. For successful refactoring there is one crucial thing we absolutely must have: Tests. Automated unit tests are the only guarantee we have that we haven’t broken the input/output behavior before refactoring. If you haven’t go back ad read my post on the matter. Then start writing them. Next thing you need is a code module. Those are views, UDFs and stored procedures. By having direct table access we can kiss fast and sweet refactoring good bye. One more point to have a database abstraction layer. And no, ORM’s don’t fall into that category. But also know that refactoring is NOT adding new functionality to your code. Many have fallen into this trap. Don’t be one of them and resist the lure of the dark side. And it’s a strong lure. We developers in general love to add new stuff to our code, but hate fixing our own mistakes or changing existing code for no apparent reason. To be a good refactorer one needs discipline and focus. Now we know that refactoring is all about changing inner workings of existing code. This can be due to performance optimizations, changing internal code workflows or some other reason. This is a typical black box scenario to the outside world. If we upgrade the car engine it still has to drive on the road (preferably faster) and not fly (no matter how cool that would be). Also be aware that white box tests will break when we refactor. What to refactor in a database Refactoring databases doesn’t happen that often but when it does it can include a lot of stuff. Let us look at a few common cases. Adding or removing database schema objects Adding, removing or changing table columns in any way, adding constraints, keys, etc… All of these can be counted as internal changes not visible to the data consumer. But each of these carries a potential input/output behavior change. Dropping a column can result in views not working anymore or stored procedure logic crashing. Adding a unique constraint shows duplicated data that shouldn’t exist. Foreign keys break a truncate table command executed from an application that runs once a month. All these scenarios are very real and can happen. With the proper database abstraction layer fully covered with black box tests we can make sure something like that does not happen (hopefully at all). Changing physical structures Physical structures include heaps, indexes and partitions. We can pretty much add or remove those without changing the data returned by the database. But the performance can be affected. So here we use our performance tests. We do have them, right? Just by adding a single index we can achieve orders of magnitude performance improvement. Won’t that make users happy? But what if that index causes our write operations to crawl to a stop. again we have to test this. There are a lot of things to think about and have tests for. Without tests we can’t do successful refactoring! Fixing bad code We all have some bad code in our systems. We usually refer to that code as code smell as they violate good coding practices. Examples of such code smells are SQL injection, use of SELECT *, scalar UDFs or cursors, etc… Each of those is huge code smell and can result in major code changes. Take SELECT * from example. If we remove a column from a table the client using that SELECT * statement won’t have a clue about that until it runs. Then it will gracefully crash and burn. Not to mention the widely unknown SELECT * view refresh problem that Tomas LaRock (@SQLRockstar on Twitter) and Colin Stasiuk (@BenchmarkIT on Twitter) talk about in detail. Go read about it, it’s informative. Refactoring this includes replacing the * with column names and most likely change to application using the database. Breaking apart huge stored procedures Have you ever seen seen a stored procedure that was 2000 lines long? I have. It’s not pretty. It hurts the eyes and sucks the will to live the next 10 minutes. They are a maintenance nightmare and turn into things no one dares to touch. I’m willing to bet that 100% of time they don’t have a single test on them. Large stored procedures (and functions) are a clear sign that they contain business logic. General opinion on good database coding practices says that business logic has no business in the database. That’s the applications part. Refactoring such behemoths requires writing lots of edge case tests for the stored procedure input/output behavior and then start to refactor it. First we split the logic inside into smaller parts like new stored procedures and UDFs. Those then get called from the master stored procedure. Once we’ve successfully modularized the database code it’s best to transfer that logic into the applications consuming it. This only leaves the stored procedure with common data manipulation logic. Of course this isn’t always possible so having a plethora of performance and behavior unit tests is absolutely necessary to confirm we’ve actually improved the codebase in some way.   Refactoring is not a popular chore amongst developers or managers. The former don’t like fixing old code, the latter can’t see the financial benefit. Remember how we talked about being lousy at estimating future costs in the previous post? But there comes a time when it must be done. Hopefully I’ve given you some ideas how to get started. In the last post of the series we’ll take a look at the tools to use and an example of testing and refactoring.

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• projection / view matrix: the object is bigger than it should and depth does not affect vertices

  - by Francesco Noferi

  I'm currently trying to write a C 3D software rendering engine from scratch just for fun and to have an insight on what OpenGL does behind the scene and what 90's programmers had to do on DOS. I have written my own matrix library and tested it without noticing any issues, but when I tried projecting the vertices of a simple 2x2 cube at 0,0 as seen by a basic camera at 0,0,10, the cube seems to appear way bigger than the application's window. If I scale the vertices' coordinates down by 8 times I can see a proper cube centered on the screen. This cube doesn't seem to be in perspective: wheen seen from the front, the back vertices pe rfectly overlap with the front ones, so I'm quite sure it's not correct. this is how I create the view and projection matrices (vec4_initd initializes the vectors with w=0, vec4_initw initializes the vectors with w=1): void mat4_lookatlh(mat4 *m, const vec4 *pos, const vec4 *target, const vec4 *updirection) { vec4 fwd, right, up; // fwd = norm(pos - target) fwd = *target; vec4_sub(&fwd, pos); vec4_norm(&fwd); // right = norm(cross(updirection, fwd)) vec4_cross(updirection, &fwd, &right); vec4_norm(&right); // up = cross(right, forward) vec4_cross(&fwd, &right, &up); // orientation and translation matrices combined vec4_initd(&m->a, right.x, up.x, fwd.x); vec4_initd(&m->b, right.y, up.y, fwd.y); vec4_initd(&m->c, right.z, up.z, fwd.z); vec4_initw(&m->d, -vec4_dot(&right, pos), -vec4_dot(&up, pos), -vec4_dot(&fwd, pos)); } void mat4_perspectivefovrh(mat4 *m, float fovdegrees, float aspectratio, float near, float far) { float h = 1.f / tanf(ftoradians(fovdegrees / 2.f)); float w = h / aspectratio; vec4_initd(&m->a, w, 0.f, 0.f); vec4_initd(&m->b, 0.f, h, 0.f); vec4_initw(&m->c, 0.f, 0.f, -far / (near - far)); vec4_initd(&m->d, 0.f, 0.f, (near * far) / (near - far)); } this is how I project my vertices: void device_project(device *d, const vec4 *coord, const mat4 *transform, int *projx, int *projy) { vec4 result; mat4_mul(transform, coord, &result); *projx = result.x * d->w + d->w / 2; *projy = result.y * d->h + d->h / 2; } void device_rendervertices(device *d, const camera *camera, const mesh meshes[], int nmeshes, const rgba *color) { int i, j; mat4 view, projection, world, transform, projview; mat4 translation, rotx, roty, rotz, transrotz, transrotzy; int projx, projy; // vec4_unity = (0.f, 1.f, 0.f, 0.f) mat4_lookatlh(&view, &camera->pos, &camera->target, &vec4_unity); mat4_perspectivefovrh(&projection, 45.f, (float)d->w / (float)d->h, 0.1f, 1.f); for (i = 0; i < nmeshes; i++) { // world matrix = translation * rotz * roty * rotx mat4_translatev(&translation, meshes[i].pos); mat4_rotatex(&rotx, ftoradians(meshes[i].rotx)); mat4_rotatey(&roty, ftoradians(meshes[i].roty)); mat4_rotatez(&rotz, ftoradians(meshes[i].rotz)); mat4_mulm(&translation, &rotz, &transrotz); // transrotz = translation * rotz mat4_mulm(&transrotz, &roty, &transrotzy); // transrotzy = transrotz * roty = translation * rotz * roty mat4_mulm(&transrotzy, &rotx, &world); // world = transrotzy * rotx = translation * rotz * roty * rotx // transform matrix mat4_mulm(&projection, &view, &projview); // projview = projection * view mat4_mulm(&projview, &world, &transform); // transform = projview * world = projection * view * world for (j = 0; j < meshes[i].nvertices; j++) { device_project(d, &meshes[i].vertices[j], &transform, &projx, &projy); device_putpixel(d, projx, projy, color); } } } this is how the cube and camera are initialized: // test mesh cube = &meshlist[0]; mesh_init(cube, "Cube", 8); cube->rotx = 0.f; cube->roty = 0.f; cube->rotz = 0.f; vec4_initw(&cube->pos, 0.f, 0.f, 0.f); vec4_initw(&cube->vertices[0], -1.f, 1.f, 1.f); vec4_initw(&cube->vertices[1], 1.f, 1.f, 1.f); vec4_initw(&cube->vertices[2], -1.f, -1.f, 1.f); vec4_initw(&cube->vertices[3], -1.f, -1.f, -1.f); vec4_initw(&cube->vertices[4], -1.f, 1.f, -1.f); vec4_initw(&cube->vertices[5], 1.f, 1.f, -1.f); vec4_initw(&cube->vertices[6], 1.f, -1.f, 1.f); vec4_initw(&cube->vertices[7], 1.f, -1.f, -1.f); // main camera vec4_initw(&maincamera.pos, 0.f, 0.f, 10.f); maincamera.target = vec4_zerow; and, just to be sure, this is how I compute matrix multiplications: void mat4_mul(const mat4 *m, const vec4 *va, vec4 *vb) { vb->x = m->a.x * va->x + m->b.x * va->y + m->c.x * va->z + m->d.x * va->w; vb->y = m->a.y * va->x + m->b.y * va->y + m->c.y * va->z + m->d.y * va->w; vb->z = m->a.z * va->x + m->b.z * va->y + m->c.z * va->z + m->d.z * va->w; vb->w = m->a.w * va->x + m->b.w * va->y + m->c.w * va->z + m->d.w * va->w; } void mat4_mulm(const mat4 *ma, const mat4 *mb, mat4 *mc) { mat4_mul(ma, &mb->a, &mc->a); mat4_mul(ma, &mb->b, &mc->b); mat4_mul(ma, &mb->c, &mc->c); mat4_mul(ma, &mb->d, &mc->d); }

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• Evaluating Solutions to Manage Product Compliance? Don't Wait Much Longer

  - by Kerrie Foy

  Depending on severity, product compliance issues can cause all sorts of problems from run-away budgets to business closures. But effective policies and safeguards can create a strong foundation for innovation, productivity, market penetration and competitive advantage. If you’ve been putting off a systematic approach to product compliance, it is time to reconsider that decision, or indecision. Why now?  No matter what industry, companies face a litany of worldwide and regional regulations that require proof of product compliance and environmental friendliness for market access.  For example, Restriction of Hazardous Substances (RoHS) is a regulation that restricts the use of six dangerous materials used in the manufacture of electronic and electrical equipment.  ROHS was originally adopted by the European Union in 2003 for implementation in 2006, and it has evolved over time through various regional versions for North America, China, Japan, Korea, Norway and Turkey.  In addition, the RoHS directive allowed for material exemptions used in Medical Devices, but that exemption ends in 2014.   Additional regulations worth watching are the Battery Directive, Waste Electrical and Electronic Equipment (WEEE), and Registration, Evaluation, Authorization and Restriction of Chemicals (REACH) directives.  Additional evolving regulations are coming from governing bodies like the Food and Drug Administration (FDA) and the International Organization for Standardization (ISO). Corporate sustainability initiatives are also gaining urgency and influencing product design. In a survey of 405 corporations in the Global 500 by Carbon Disclosure Project, co-written by PwC (CDP Global 500 Climate Change Report 2012 entitled Business Resilience in an Uncertain, Resource-Constrained World), 48% of the respondents indicated they saw potential to create new products and business services as a response to climate change. Just 21% reported a dedicated budget for the research. However, the report goes on to explain that those few companies are winning over new customers and driving additional profits by exploiting their abilities to adapt to environmental needs. The article cites Dell as an example – Dell has invested in research to develop new products designed to reduce its customers’ emissions by more than 10 million metric tons of CO2e per year. This reduction in emissions should save Dell’s customers over $1billion per year as a result! Over time we expect to see many additional companies prove that eco-design provides marketplace benefits through differentiation and direct customer value. How do you meet compliance requirements and also successfully invest in eco-friendly designs? No doubt companies struggle to answer this question. After all, the journey to get there may involve transforming business models, go-to-market strategies, supply networks, quality assurance policies and compliance processes per the rapidly evolving global and regional directives. There may be limited executive focus on the initiative, inability to quantify noncompliance, or not enough resources to justify investment. To make things even more difficult to address, compliance responsibility can be a passionate topic within an organization, making the prospect of change on an enterprise scale problematic and time-consuming. Without a single source of truth for product data and without proper processes in place, ensuring product compliance burgeons into a crushing task that is cost-prohibitive and overwhelming to an organization. With all the overhead, certain markets or demographics become simply inaccessible. Therefore, the risk to consumer goodwill and satisfaction, revenue, business continuity, and market potential is too great not to solve the compliance challenge. Companies are beginning to adapt and even thrive in today’s highly regulated and transparent environment by implementing systematic approaches to product compliance that are more than functional bandages but revenue-generating engines. Consider partnering with Oracle to help you address your compliance needs. Many of the world’s most innovative leaders and pioneers are leveraging Oracle’s Agile Product Lifecycle Management (PLM) portfolio of enterprise applications to manage the product value chain, centralize product data, automate processes, and launch more eco-friendly products to market faster.   Particularly, the Agile Product Governance & Compliance (PG&C) solution provides out-of-the-box functionality to integrate actionable regulatory information into the enterprise product record from the ideation to the disposal/recycling phase. Agile PG&C makes it possible to efficiently manage compliance per corporate green initiatives as well as regional and global directives. Options are critical, but so is ease-of-use. Anyone who’s grappled with compliance policy knows legal interpretation plays a major role in determining how an organization responds to regulation. Agile PG&C gives you the freedom to configure product compliance per your needs, while maintaining rigorous control over the product record in an easy-to-use interface that facilitates adoption efforts. It allows you to assign regulations as specifications for a part or BOM roll-up. Each specification has a threshold value that alerts you to a non-compliance issue if the threshold value is exceeded. Set however many regulations as specifications you need to make sure a product can be sold in your target countries. Another option is to implement like one of our leading consumer electronics customers and define your own “catch-all” specification to ensure compliance in all markets. You can give your suppliers secure access to enter their component data or integrate a third party’s data. With Agile PG&C you are able to design compliance earlier into your products to reduce cost and improve quality downstream when stakes are higher. Agile PG&C is a comprehensive solution that makes product compliance more reliable and efficient. Throughout product lifecycles, use the solution to support full material disclosures, efficiently manage declarations with your suppliers, feed compliance data into a corrective action if a product must be changed, and swiftly satisfy audits by showing all due diligence tracked in one solution. Given the compounding regulation and consumer focus on urgent environmental issues, now is the time to act. Implementing an enterprise, systematic approach to product compliance is a competitive investment. From the start, Agile Product Governance & Compliance enables companies to confidently design for compliance and sustainability, reduce the cost of compliance, minimize the risk of business interruption, deliver responsible products, and inspire new innovation.  Don’t wait any longer! To find out more about Agile Product Governance & Compliance download the data sheet, contact your sales representative, or call Oracle at 1-800-633-0738. Many thanks to Shane Goodwin, Senior Manager, Oracle Agile PLM Product Management, for contributions to this article. 

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• Waterfall Model (SDLC) vs. Prototyping Model

  The characters in the fable of the Tortoise and the Hare can easily be used to demonstrate the similarities and differences between the Waterfall and Prototyping software development models. This children fable is about a race between a consistently slow moving but steadfast turtle and an extremely fast but unreliable rabbit. After closely comparing each character’s attributes in correlation with both software development models, a trend seems to appear in that the Waterfall closely resembles the Tortoise in that Waterfall Model is typically a slow moving process that is broken up in to multiple sequential steps that must be executed in a standard linear pattern. The Tortoise can be quoted several times in the story saying “Slow and steady wins the race.” This is the perfect mantra for the Waterfall Model in that this model is seen as a cumbersome and slow moving. Waterfall Model Phases Requirement Analysis & Definition This phase focuses on defining requirements for a project that is to be developed and determining if the project is even feasible. Requirements are collected by analyzing existing systems and functionality in correlation with the needs of the business and the desires of the end users. The desired output for this phase is a list of specific requirements from the business that are to be designed and implemented in the subsequent steps. In addition this phase is used to determine if any value will be gained by completing the project. System Design This phase focuses primarily on the actual architectural design of a system, and how it will interact within itself and with other existing applications. Projects at this level should be viewed at a high level so that actual implementation details are decided in the implementation phase. However major environmental decision like hardware and platform decision are typically decided in this phase. Furthermore the basic goal of this phase is to design an application at the system level in those classes, interfaces, and interactions are defined. Additionally decisions about scalability, distribution and reliability should also be considered for all decisions. The desired output for this phase is a functional  design document that states all of the architectural decisions that have been made in regards to the project as well as a diagrams like a sequence and class diagrams. Software Design This phase focuses primarily on the refining of the decisions found in the functional design document. Classes and interfaces are further broken down in to logical modules based on the interfaces and interactions previously indicated. The output of this phase is a formal design document. Implementation / Coding This phase focuses primarily on implementing the previously defined modules in to units of code. These units are developed independently are intergraded as the system is put together as part of a whole system. Software Integration & Verification This phase primarily focuses on testing each of the units of code developed as well as testing the system as a whole. There are basic types of testing at this phase and they include: Unit Test and Integration Test. Unit Test are built to test the functionality of a code unit to ensure that it preforms its desired task. Integration testing test the system as a whole because it focuses on results of combining specific units of code and validating it against expected results. The output of this phase is a test plan that includes test with expected results and actual results. System Verification This phase primarily focuses on testing the system as a whole in regards to the list of project requirements and desired operating environment. Operation & Maintenance his phase primarily focuses on handing off the competed project over to the customer so that they can verify that all of their requirements have been met based on their original requirements. This phase will also validate the correctness of their requirements and if any changed need to be made. In addition, any problems not resolved in the previous phase will be handled in this section. The Waterfall Model’s linear and sequential methodology does offer a project certain advantages and disadvantages. Advantages of the Waterfall Model Simplistic to implement and execute for projects and/or company wide Limited demand on resources Large emphasis on documentation Disadvantages of the Waterfall Model Completed phases cannot be revisited regardless if issues arise within a project Accurate requirement are never gather prior to the completion of the requirement phase due to the lack of clarification in regards to client’s desires. Small changes or errors that arise in applications may cause additional problems The client cannot change any requirements once the requirements phase has been completed leaving them no options for changes as they see their requirements changes as the customers desires change. Excess documentation Phases are cumbersome and slow moving Learn more about the Major Process in the Sofware Development Life Cycle and Waterfall Model. Conversely, the Hare shares similar traits with the prototyping software development model in that ideas are rapidly converted to basic working examples and subsequent changes are made to quickly align the project with customers desires as they are formulated and as software strays from the customers vision. The basic concept of prototyping is to eliminate the use of well-defined project requirements. Projects are allowed to grow as the customer needs and request grow. Projects are initially designed according to basic requirements and are refined as requirement become more refined. This process allows customer to feel their way around the application to ensure that they are developing exactly what they want in the application This model also works well for determining the feasibility of certain approaches in regards to an application. Prototypes allow for quickly developing examples of implementing specific functionality based on certain techniques. Advantages of Prototyping Active participation from users and customers Allows customers to change their mind in specifying requirements Customers get a better understanding of the system as it is developed Earlier bug/error detection Promotes communication with customers Prototype could be used as final production Reduced time needed to develop applications compared to the Waterfall method Disadvantages of Prototyping Promotes constantly redefining project requirements that cause major system rewrites Potential for increased complexity of a system as scope of the system expands Customer could believe the prototype as the working version. Implementation compromises could increase the complexity when applying updates and or application fixes When companies trying to decide between the Waterfall model and Prototype model they need to evaluate the benefits and disadvantages for both models. Typically smaller companies or projects that have major time constraints typically head for more of a Prototype model approach because it can reduce the time needed to complete the project because there is more of a focus on building a project and less on defining requirements and scope prior to the start of a project. On the other hand, Companies with well-defined requirements and time allowed to generate proper documentation should steer towards more of a waterfall model because they are in a position to obtain clarified requirements and have to design and optimal solution prior to the start of coding on a project.

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• DRY and SRP

  - by Timothy Klenke

  Originally posted on: http://geekswithblogs.net/TimothyK/archive/2014/06/11/dry-and-srp.aspxKent Beck’s XP Simplicity Rules (aka Four Rules of Simple Design) are a prioritized list of rules that when applied to your code generally yield a great design.  As you’ll see from the above link the list has slightly evolved over time.  I find today they are usually listed as: All Tests Pass Don’t Repeat Yourself (DRY) Express Intent Minimalistic These are prioritized.  If your code doesn’t work (rule 1) then everything else is forfeit.  Go back to rule one and get the code working before worrying about anything else. Over the years the community have debated whether the priority of rules 2 and 3 should be reversed.  Some say a little duplication in the code is OK as long as it helps express intent.  I’ve debated it myself.  This recent post got me thinking about this again, hence this post.   I don’t think it is fair to compare “Expressing Intent” against “DRY”.  This is a comparison of apples to oranges.  “Expressing Intent” is a principal of code quality.  “Repeating Yourself” is a code smell.  A code smell is merely an indicator that there might be something wrong with the code.  It takes further investigation to determine if a violation of an underlying principal of code quality has actually occurred. For example “using nouns for method names”, “using verbs for property names”, or “using Booleans for parameters” are all code smells that indicate that code probably isn’t doing a good job at expressing intent.  They are usually very good indicators.  But what principle is the code smell of Duplication pointing to and how good of an indicator is it? Duplication in the code base is bad for a couple reasons.  If you need to make a change and that needs to be made in a number of locations it is difficult to know if you have caught all of them.  This can lead to bugs if/when one of those locations is overlooked.  By refactoring the code to remove all duplication there will be left with only one place to change, thereby eliminating this problem. With most projects the code becomes the single source of truth for a project.  If a production code base is inconsistent with a five year old requirements or design document the production code that people are currently living with is usually declared as the current reality (or truth).  Requirement or design documents at this age in a project life cycle are usually of little value. Although comparing production code to external documentation is usually straight forward, duplication within the code base muddles this declaration of truth.  When code is duplicated small discrepancies will creep in between the two copies over time.  The question then becomes which copy is correct?  As different factions debate how the software should work, trust in the software and the team behind it erodes. The code smell of Duplication points to a violation of the “Single Source of Truth” principle.  Let me define that as: A stakeholder’s requirement for a software change should never cause more than one class to change. Violation of the Single Source of Truth principle will always result in duplication in the code.  However, the inverse is not always true.  Duplication in the code does not necessarily indicate that there is a violation of the Single Source of Truth principle. To illustrate this, let’s look at a retail system where the system will (1) send a transaction to a bank and (2) print a receipt for the customer.  Although these are two separate features of the system, they are closely related.  The reason for printing the receipt is usually to provide an audit trail back to the bank transaction.  Both features use the same data:  amount charged, account number, transaction date, customer name, retail store name, and etcetera.  Because both features use much of the same data, there is likely to be a lot of duplication between them.  This duplication can be removed by making both features use the same data access layer. Then start coming the divergent requirements.  The receipt stakeholder wants a change so that the account number has the last few digits masked out to protect the customer’s privacy.  That can be solve with a small IF statement whilst still eliminating all duplication in the system.  Then the bank wants to take a picture of the customer as well as capture their signature and/or PIN number for enhanced security.  Then the receipt owner wants to pull data from a completely different system to report the customer’s loyalty program point total. After a while you realize that the two stakeholders have somewhat similar, but ultimately different responsibilities.  They have their own reasons for pulling the data access layer in different directions.  Then it dawns on you, the Single Responsibility Principle: There should never be more than one reason for a class to change. In this example we have two stakeholders giving two separate reasons for the data access class to change.  It is clear violation of the Single Responsibility Principle.  That’s a problem because it can often lead the project owner pitting the two stakeholders against each other in a vein attempt to get them to work out a mutual single source of truth.  But that doesn’t exist.  There are two completely valid truths that the developers need to support.  How is this to be supported and honour the Single Responsibility Principle?  The solution is to duplicate the data access layer and let each stakeholder control their own copy. The Single Source of Truth and Single Responsibility Principles are very closely related.  SST tells you when to remove duplication; SRP tells you when to introduce it.  They may seem to be fighting each other, but really they are not.  The key is to clearly identify the different responsibilities (or sources of truth) over a system.  Sometimes there is a single person with that responsibility, other times there are many.  This can be especially difficult if the same person has dual responsibilities.  They might not even realize they are wearing multiple hats. In my opinion Single Source of Truth should be listed as the second rule of simple design with Express Intent at number three.  Investigation of the DRY code smell should yield to the proper application SST, without violating SRP.  When necessary leave duplication in the system and let the class names express the different people that are responsible for controlling them.  Knowing all the people with responsibilities over a system is the higher priority because you’ll need to know this before you can express it.  Although it may be a code smell when there is duplication in the code, it does not necessarily mean that the coder has chosen to be expressive over DRY or that the code is bad.

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• how to do event checks for loops?

  - by yao jiang

  I am having some trouble getting the logic down for this. Currently, I have an app that animates the astar pathfinding algorithm. On start of the app, the ui will show the following: User can press "space" to randomly choose start/end coords, then the app will animate it. Or, user can choose the start/end by left-click/right-click. During the animation, the user can also left-click to generate blocks, or right-click to choose a new destiantion. Where I am stuck at is how to handle the events while the app is animating. Right now, I am checking events in the main loop, then when the app is animating, I do event checks again. While it works fine, I feel that I am probably doing it wrong. What is the proper way of setting up the main loop that will handle the events while the app is animating? In main loop, the app start animating once user choose start/end. In my draw function, I am putting another event checker in there. def clear(rows): for r in range(rows): for c in range(rows): if r%3 == 1 and c%3 == 1: color = brown; grid[r][c] = 1; buildCoor.append(r); buildCoor.append(c); else: color = white; grid[r][c] = 0; pick_image(screen, color, width*c, height*r); pygame.display.flip(); os.system('cls'); # draw out the grid def draw(start, end, grid, route_coord): # draw the end coords color = red; pick_image(screen, color, width*end[1],height*end[0]); pygame.display.flip(); # then draw the rest of the route for i in range(len(route_coord)): # pausing because we want animation time.sleep(speed); # get the x/y coords x,y = route_coord[i]; event_on = False; if grid[x][y] == 2: color = green; elif grid[x][y] == 3: color = blue; for event in pygame.event.get(): if event.type == pygame.MOUSEBUTTONDOWN: if event.button == 3: print "destination change detected, rerouting"; # get mouse position, px coords pos = pygame.mouse.get_pos(); # get grid coord c = pos[0] // width; r = pos[1] // height; grid[r][c] = 4; end = [r, c]; elif event.button == 1: print "user generated event"; pos = pygame.mouse.get_pos(); # get grid coord c = pos[0] // width; r = pos[1] // height; # mark it as a block for now grid[r][c] = 1; event_on = True; if check_events([x,y]) or event_on: # there is an event # mark it as a block for now grid[y][x] = 1; pick_image(screen, event_x, width*y, height*x); pygame.display.flip(); # then find a new route new_start = route_coord[i-1]; marked_grid, route_coord = find_route(new_start, end, grid); draw(new_start, end, grid, route_coord); return; # just end draw here so it wont throw the "index out of range" error elif grid[x][y] == 4: color = red; pick_image(screen, color, width*y, height*x); pygame.display.flip(); # clear route coord list, otherwise itll just add more unwanted coords route_coord_list[:] = []; clear(rows); # main loop while not done: # check the events for event in pygame.event.get(): # mouse events if event.type == pygame.MOUSEBUTTONDOWN: # get mouse position, px coords pos = pygame.mouse.get_pos(); # get grid coord c = pos[0] // width; r = pos[1] // height; # find which button pressed, highlight grid accordingly if event.button == 1: # left click, start coords if grid[r][c] == 2: grid[r][c] = 0; color = white; elif grid[r][c] == 0 or grid[r][c] == 4: grid[r][c] = 2; start = [r,c]; color = green; else: grid[r][c] = 1; color = brown; elif event.button == 3: # right click, end coords if grid[r][c] == 4: grid[r][c] = 0; color = white; elif grid[r][c] == 0 or grid[r][c] == 2: grid[r][c] = 4; end = [r,c]; color = red; else: grid[r][c] = 1; color = brown; pick_image(screen, color, width*c, height*r); # keyboard events elif event.type == pygame.KEYDOWN: clear(rows); # one way to quit program if event.key == pygame.K_ESCAPE: print "program will now exit."; done = True; # space key for random start/end elif event.key == pygame.K_SPACE: # first clear the ui clear(rows); # now choose random start/end coords buildLoc = zip(buildCoor,buildCoor[1:])[::2]; #print buildLoc; (start_x, start_y, end_x, end_y) = pick_point(); while (start_x, start_y) in buildLoc or (end_x, end_y) in buildLoc: (start_x, start_y, end_x, end_y) = pick_point(); clear(rows); print "chosen random start/end coords: ", (start_x, start_y, end_x, end_y); if (start_x, start_y) in buildLoc or (end_x, end_y) in buildLoc: print "error"; # draw the route marked_grid, route_coord = find_route([start_x,start_y],[end_x,end_y], grid); draw([start_x, start_y], [end_x, end_y], marked_grid, route_coord); # return key for user defined start/end elif event.key == pygame.K_RETURN: # first clear the ui clear(rows); # get the user defined start/end print "user defined start/end are: ", (start[0], start[1], end[0], end[1]); grid[start[0]][start[1]] = 1; grid[end[0]][end[1]] = 2; # draw the route marked_grid, route_coord = find_route(start, end, grid); draw(start, end, marked_grid, route_coord); # c to clear the screen elif event.key == pygame.K_c: print "clearing screen."; clear(rows); # go fullscreen elif event.key == pygame.K_f: if not full_sc: pygame.display.set_mode([1366, 768], pygame.FULLSCREEN); full_sc = True; rows = 15; clear(rows); else: pygame.display.set_mode(size); full_sc = False; # +/- key to change speed of animation elif event.key == pygame.K_LEFTBRACKET: if speed >= 0.1: print SPEED_UP; speed = speed_up(speed); print speed; else: print FASTEST; print speed; elif event.key == pygame.K_RIGHTBRACKET: if speed < 1.0: print SPEED_DOWN; speed = slow_down(speed); print speed; else: print SLOWEST print speed; # second method to quit program elif event.type == pygame.QUIT: print "program will now exit."; done = True; # limit to 20 fps clock.tick(20); # update the screen pygame.display.flip();

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• Emtel Knowledge Series - Q2/2014

  From Cyber Island to Smart Mauritius Cyber Island? Smart Mauritius? - What is Emtel talking about? "With the majority of the population living in urban environments today, the concept of "Smart Cities" has become an urgent necessity. "Smart Cities" refer to an urban transformation which, by using latest ICT technologies makes cities more efficient. Many Governments are setting out ambitious plans to build the cities of the future based on massive connectivity, high bandwidth communications, intelligent sensors and analysis of huge volumes of data. Various researches have shown four key enablers for smart city success - Government leadership, suitable technology infrastructure, solid public-private partnerships and engaged citizens. It is around these enabling factors that telecoms companies can play a vital role in assisting governments to deliver on the smart city vision." The Emtel Knowledge Series goes in compliance with Emtel's 25th anniversary celebrations throughout the year and the master of ceremony, Kim Andersen, mentioned that there will be more upcoming events on a quarterly base. As a representative of the Mauritius Software Craftsmanship Community (MSCC) there was absolutely no hesitation to join in again. Following my visit to the first Emtel Knowledge Series workshop back in February this year, it was great to have another opportunity to meet and exchange with technology experts. But quite frankly what is it with those buzz words... As far as I remember and how it was mentioned "Cyber Island" is an old initiative from around 2005/2006 which has been refreshed in 2010. It implies the empowerment of Information & Communication Technologies (ICT) as an essential factor of growth by the government here in Mauritius. Actually, the first promotional period of Cyber Island brought me here but that's another story. The venue and its own problems Like last time the event was organised and held at the Conference Hall at Cyber Tower I in Ebene. As I've been working there for some years, I know about the frustrating situation of finding a proper parking. So, does Smart Island include better solutions for the search of parking spaces? Maybe, let's see whether I will be able to answer that question at the end of the article. Anyway, after circling around the tower almost two times, I finally got a decent space to put the car, without risking to get a ticket or damage actually. International speakers and their experience Once again, Emtel did a great job to get international expertise onto the stage to share their experience and vision on this kind of embarkment. Personally, I really appreciated the fact they were speakers of global reach and could provide own-experience knowledge. Johan Gott spoke about the fundamental change that the Swedish government ignited in order to move their society and workers' environment away from heavy industry towards a knowledge-based approach. Additionally, we spoke about the effort and transformation of New York City into a greener and more efficient Smart City. Given modern technology he also advised that any kind of available Big Data should be opened to the general public - this openness would provide a playground for anyone to garner new ideas and most probably solid solutions of which no one else thought about before. Emtel Knowledge Series on moving from Cyber Island to Smart Mauritus Later during the afternoon that exact statement regarding openness to and transparency of government-owned Big Data has been emphasised again by the Danish speaker Kim Andersen and his former colleague Mika Jantunen from Finland. Mika continued to underline the important role of the government to provide a solid foundation for a knowledge-based society and mentioned that Finnish citizens have a constitutional right to broadband connectivity. Next to free higher (tertiary) education Finland already produced a good number of innovations, among them are: First country to grant voting rights to women Free higher education Constitutional right to broadband connectivity Nokia Linux Angry Birds Sauna and others...  General access to internet via broadband and/or mobile connectivity is surely a key factor towards Smart Cities, or better said Smart Mauritius given the area dimensions and size of population. CTO Paul Valette gave the audience a brief overview of the essential role that Emtel will have to move Mauritius forward towards a knowledge-based and innovation-driven environment for its citizen. What I have seen looks really promising and with recently published information that Mauritians have 127% of mobile capacity - meaning more than 1 mobile, smartphone or tablet per person - it will be crucial to have the right infrastructure for these connected devices. How would it be possible to achieve a knowledge-based society? YouTube to the rescue!Seriously, gaining more knowledge will require to have fast access to educational course material as explained by Dr Kaviraj Sukon, General Director of the Open University of Mauritius. According to him a good number of high-profile universities in the world have opened their course libraries to the general public, among them EDX, Coursera and Open University. Nowadays, you're actually able and enabled to learn for and earn a BSc or even MSc certification on your own pace - no need to attend classed on campus. It was really impressive to see the number of available hours - more than enough for a life-long learning experience! {loadposition content_adsense} Networking in the name of MSCC As briefly mentioned above I was about to combine two approaches for this workshop. Of course, getting latest information and updates on Emtel services available, especially for my business here on the west coast of the island, but also to meet and greet new people for the MSCC. And I think it was very positive on both sides. Let me quickly describe some of the key aspects that happened during the day: Met with Arnaud Meslier and Kellie, both Microsoft to swap latest information on IT events. Hereby, I got an invite to Microsoft Windows Phone 8.1 Dev Camp. Got in touch with Arvin Lockee, Emtel to check our options to meet with the data team, and seizing the opportunity to have a visiting tour at the Emtel Data Centre. Had a great chat with Avinash Meetoo, Knowledge 7, Kim Andersen and Mika Jantunen about the situation of teaching and learning in general and specifically in the private sector here in Mauritius. Additionally, a number of various other interesting chats... Once again, I'm catching up on a couple of business cards in order to provide more background information about the MSCC, and to create a better awareness of MSCC within the local IT businesses. There is more to come soon!  Resume of the day The number of attendees during this event has been doubled or even tripled this time. The whole organisation has been improved massively and the combination of presentation and summarizing panel discussions was better than during the previous workshop back in February. Overall, once again a well-organised workshop and I'm already looking forward to join the next workshop in Q3. Update End of July we finally managed to visit the Emtel Data Centre in Arsenal. It was an interesting opportunity for some of our MSCC members.

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• Moving from Tortoise to TFS

  - by MarkPearl

  The Past A few years ago my small software company made the jump from storing code on a shared folder to source code control. At the time we had evaluated a few of the options and settled on Tortoise SVN. The main motivation for going the SVN route was that we found a great plugin for Visual Studio that allowed us to avoid the command prompt for uploading changes (like I said we are windows programmers… command prompt bad!! ) and it was free. Up to now we have been pretty happy with SVN as it removed many of the worries that I had about how safe my code was on a shared folder and also gave us the opportunity to safely have several developers work on the same project at the same time. The only times when we have been unhappy has been when we have had SVN hell days – which pretty much occur when you are doing something out of the norm and suddenly SVN just won’t resolve conflicts or something along those lines. This happens once every 4 or 5 months and is not necessarily a problem caused directly by SVN – but a problem augmented by SVN. When you have SVN hell days you want to curse SVN! With that in mind I recently have been relooking at our source code control. I have explored using GIT and was very impressed by it and have also looked at TFS. From a source code control perspective I don’t want to get into a heated discussion on which one is better – but I do want to mention that I wear two hats in my organization – software developer & manager, and with the manager hat on I tend to sway the TFS route. So when I was given a coupon to test DiscountASP.Net Team Foundation Server Service for a year, I thought it was the perfect opportunity to try TFS in a distributed environment and also make the first step towards having an integrated development management system. Some of the things that appeal to me about DiscountASP’s offering are the following… Basic management / planning facilities like to do lists inside Visual Studio Daily backup of data on the server – we are developers, not IT managers and so the more of this I could outsource the better Distributed solution – all of us work remotely and so this was a big one as well. Registering and Setting Up with DiscountASP.NET The whole registration process was simple and intuitive. The web interface is not the most visually impressive one, but it is functional and a few seconds after I clicked the last submit button a email was sitting in my inbox giving me my control panel username and suggesting that I read the “Getting Started” article. The getting started article was easy to read and understand so no complaints there either. Next to set my dev environment to work. With a few references to the getting started article I had completed the whole setup process in a matter of minutes. Ten minutes after initiating the whole thing I was logged into VS2010 and creating my first TFS project. With the service that I signed up for, I have access for 5 users – which is sufficient for my internal needs. So from what I can tell, to set the rest of us up on the system I just need to supply them with their user credentials and url. My Concerns Resolved 1) Security So, a few concerns I had about the service. First and foremost – is it secure? I would hate for someone to get access to our code and the whole idea of putting it up on the internet is a concern for me. Turning to the Knowledge Base on the DiscountASP website this is one of the first question I can see answered. According to them it is secure. I have extracted their comment below regarding this. Our TFS hosting service is secure. We only accept HTTPS connections ensuring that any client-server data transmission is encrypted. At the network level, all of our systems are protected by multiple Juniper firewalls, Tipping Point's Intrusion Detection System (see Tipping Point's case study of our use here), and we also employ DDoS mitigation to add extra layers of security. Additionally, physical access to the servers is tightly restricted. Please see the security section of this Knowledge Base article for further details. 2) Web Portal Access The other big concern I have is regarding web portal access. In the ideal world I would like to be able to give my end users access to a web portal for reporting bugs etc. When I initially read through the FAQ of the site it mentioned that there was web portal access – but from what I can see this is just for “users”. Since I am limited to 5 users for the account, it would not be practical to set up external users that we could get feedback from on bugs etc. I would be interested if this is possible – and if so if someone could post it in the comments it would be much appreciated. If this isn’t possible, it is a slight let down as we rely heavily on end user feedback to get feedback and it would have been ideal to have gotten this within the service. Other than those two items, I didn’t have any real concerns that were unresolved. So where do I go from here? So time passed by from the initial writing of this post and as work whirred in and out of my inbox I have still not had a proper opportunity to give the service a test run. Recently though things have began to slow down and then surprise surprise I had another SVN Hell day. With that experience I had a new found resolve to get our team on TFS and so today we are going to start to use the service as a team. I am hoping that I do not have TFS hell days – but if I do, I will be sure to write about them. In short - the verdict is still out on whether this service is going to be invaluable to my business or whether it will create more headaches than it is worth BUT I am hopping it will be an invaluable service. I will only really be able to determine that in a few months… till then!

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• Not attending the LUGM mini-meetup - 05. Oct 2013

  Not attending a meeting of the LUGM can be fun, too. It's getting a bit of a habit that Ish is organising small gatherings, aka mini-meetups, of the Linux User Group Mauritius/Meta (LUGM) almost every Saturday. There they mainly discuss and talk about various elements of using Linux as ones main operating systems and the possibilities you are going to have. On top of course, some tips & tricks about mastering the command line and initial steps in scripting or even writing HTML. In general, sounds like a good portion of fun and great spirit of community. Unfortunately, I'm usually quite busy with private and family matters during the weekend and so I already signalised that I wouldn't be around. Well, at least not physically... But this Saturday a couple of things worked out faster than expected and so I was hanging out on my machine. I made virtual contact with one of Pawan's messages over on Facebook... And somehow that kicked off some kind of an online game fun on basic configuration of Apache HTTPd 2.2.x, PHP 5.x and how to improve the overall performance of a newly installed blog based on WordPress. Default configuration files Nitin's website finally came alive and despite the dark theme and the hidden Apple 'fanboy' advertisement I was more interested in the technical situation. As with any new installation there is usually quite some adjustment to be done. And Nitin's page was no exception. Unfortunately, out of the box installations of Apache httpd and PHP are too verbose and expose too much information under the hood. You might think that this isn't really a problem at all, well, think about it again after completely reading this article. First, I checked the HTTP response headers - using either Chrome Developer Tools or Firefox Web Developer extension - of Nitin's page and based on that I advised him to lower the noise levels a little bit. It's not really necessary that detailed information about web server software and scripting language has to be published in every response made. Quite a number of script kiddies and exploits actually check for version specifics prior to an attack. So, removing at least version details hardens the system a little bit. In particular, I'm talking about these response values: Server X-Powered-By How to achieve that? By tweaking the configuration files... Namely, we are going to look into the following ones: apache2.conf httpd.conf .htaccess php.ini The above list contains some additional files, I'm talking about in the next paragraphs. Anyway, those are the ones involved. Tweaking Apache Open your favourite text editor and start to modify the apache2.conf. Eventually, you might like to have a quick peak at the file to see whether it is necessary to adjust it or not. Following is a handy combination of commands to get an overview of your active directives: # sudo grep -v '#' /etc/apache2/apache2.conf | grep -v '^$' | less There you keep an eye on those two Apache directives: ServerSignature Off ServerTokens Prod If that's not the case, change them as highlighted above. In order to activate your modifications you have to restart Apache httpd server. On Debian and Ubuntu you might use apache2ctl for that, on other distributions you might have to use service or run the init-scripts again: # sudo apache2ctl configtestSyntax OK# sudo apache2ctl restart Refresh your website and check the HTTP response header. Tweaking PHP5 (a little bit) Next, check your php.ini file with the following statement: # sudo grep -v ';' /etc/php5/apache2/php.ini | grep -v '^$' | less And check the value of expose_php = Off Again, if it's not as highlighted, change it... Some more Apache love Okay, back to Apache it might also be interesting to improve the situation about browser caching and removing more obsolete information. When you run your website against the usual performance checks like Google Page Speed and Yahoo YSlow you might see those check points with bad grades on a standard, default configuration. Well, this can be done easily. Configure entity tags (ETags) ETags are only interesting when you run your websites on a farm of multiple web servers. Removing this data for your static resources is very simple in Apache. As we are going to deal with the HTTP response header information you have to ensure that Apache is capable to manipulate them. First, check your enabled modules: # sudo ls -al /etc/apache2/mods-enabled/ | grep headers And in case that the 'headers' module is not listed, you have to enable it from the available ones: # sudo a2enmod headers Second, check your httpd.conf file (in case it exists): # sudo grep -v '#' /etc/apache2/httpd.conf | grep -v '^$' | less In newer (better said fresh) installations you might have to create a new configuration file below your conf.d folder with your favourite text editor like so: # sudo nano /etc/apache2/conf.d/headers.conf Then, in order to tweak your HTTP responses either check for those lines or add them: Header unset ETagFileETag None In case that your file doesn't exist or those lines are missing, feel free to create/add them. Afterwards, check your Apache configuration syntax and restart your running instances as already shown above: # sudo apache2ctl configtestSyntax OK# sudo apache2ctl restart Add Expires headers To improve the loading performance of your website, you should take some care into the proper configuration of how to leverage the browser's ability to cache certain resources and files. This is done by adding an Expires: value to the HTTP response header. Generally speaking it is advised that you specify a near-future, read: 1 week or a little bit more, for your static content like JavaScript files or Cascading Style Sheets. One solution to adjust this is to put some instructions into the .htaccess file in the root folder of your web site. Of course, this could also be placed into a more generic location of your Apache installation but honestly, I'd like to keep this at the web site level. Following some adjustments I'm currently using on this blog site: # Turn on Expires and set default to 0ExpiresActive OnExpiresDefault A0 # Set up caching on media files for 1 year (forever?)<FilesMatch "\.(flv|ico|pdf|avi|mov|ppt|doc|mp3|wmv|wav)$">ExpiresDefault A29030400Header append Cache-Control "public"</FilesMatch> # Set up caching on media files for 1 week<FilesMatch "\.(js|css)$">ExpiresDefault A604800Header append Cache-Control "public"</FilesMatch> # Set up caching on media files for 31 days<FilesMatch "\.(gif|jpg|jpeg|png|swf)$">ExpiresDefault A2678400Header append Cache-Control "public"</FilesMatch> As we are editing the .htaccess files, it is not necessary to restart Apache. In case that your web site doesn't load anymore or you're experiencing an error while trying to restart your httpd, check that the 'expires' module is actually an enabled module: # ls -al /etc/apache2/mods-enabled/ | grep expires# sudo a2enmod expires Of course, the instructions above a re not feature complete but I hope that they might provide a better default configuration for your LAMP stack. Resume of the day Within a couple of hours, and while being occupied with an eLearning course on SQL Server 2012, I had some good fun in helping and assisting other LUGM members while they were some kilometers away at Bagatelle. According to other blog articles it seems that Nitin had quite some moments of desperation. Just for the records: At no time it was my intention to either kick his butt or pull a leg on him. Simply, providing some input based on the lessons I've learned over the last couple of years configuring Apache HTTPd and PHP. Check out the other blogs, too: LUGM mini-meetup... Epic! Superb Saturday Linux Meetup And last but not least, the man himself: The end of a new beginning Cheers, and happy community'ing! Updates Due to our weekly Code & Coffee sessions in the MSCC community, I had a chance to talk to Nitin directly and he showed me the problems directly on his machine. This led to update this article hence the paragraphs on enabling the modules 'headers' and 'expires'.

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• How to Recover From a Virus Infection: 3 Things You Need to Do

  - by Chris Hoffman

  If your computer becomes infected with a virus or another piece of malware, removing the malware from your computer is only the first step. There’s more you need to do to ensure you’re secure. Note that not every antivirus alert is an actual infection. If your antivirus program catches a virus before it ever gets a chance to run on your computer, you’re safe. If it catches the malware later, you have a bigger problem. Change Your Passwords You’ve probably used your computer to log into your email, online banking websites, and other important accounts. Assuming you had malware on your computer, the malware could have logged your passwords and uploaded them to a malicious third party. With just your email account, the third party could reset your passwords on other websites and gain access to almost any of your online accounts. To prevent this, you’ll want to change the passwords for your important accounts — email, online banking, and whatever other important accounts you’ve logged into from the infected computer. You should probably use another computer that you know is clean to change the passwords, just to be safe. When changing your passwords, consider using a password manager to keep track of strong, unique passwords and two-factor authentication to prevent people from logging into your important accounts even if they know your password. This will help protect you in the future. Ensure the Malware Is Actually Removed Once malware gets access to your computer and starts running, it has the ability to do many more nasty things to your computer. For example, some malware may install rootkit software and attempt to hide itself from the system. Many types of Trojans also “open the floodgates” after they’re running, downloading many different types of malware from malicious web servers to the local system. In other words, if your computer was infected, you’ll want to take extra precautions. You shouldn’t assume it’s clean just because your antivirus removed what it found. It’s probably a good idea to scan your computer with multiple antivirus products to ensure maximum detection. You may also want to run a bootable antivirus program, which runs outside of Windows. Such bootable antivirus programs will be able to detect rootkits that hide themselves from Windows and even the software running within Windows. avast! offers the ability to quickly create a bootable CD or USB drive for scanning, as do many other antivirus programs. You may also want to reinstall Windows (or use the Refresh feature on Windows 8) to get your computer back to a clean state. This is more time-consuming, especially if you don’t have good backups and can’t get back up and running quickly, but this is the only way you can have 100% confidence that your Windows system isn’t infected. It’s all a matter of how paranoid you want to be. Figure Out How the Malware Arrived If your computer became infected, the malware must have arrived somehow. You’ll want to examine your computer’s security and your habits to prevent more malware from slipping through in the same way. Windows is complex. For example, there are over 50 different types of potentially dangerous file extensions that can contain malware to keep track of. We’ve tried to cover many of the most important security practices you should be following, but here are some of the more important questions to ask: Are you using an antivirus? – If you don’t have an antivirus installed, you should. If you have Microsoft Security Essentials (known as Windows Defender on Windows 8), you may want to switch to a different antivirus like the free version of avast!. Microsoft’s antivirus product has been doing very poorly in tests. Do you have Java installed? – Java is a huge source of security problems. The majority of computers on the Internet have an out-of-date, vulnerable version of Java installed, which would allow malicious websites to install malware on your computer. If you have Java installed, uninstall it. If you actually need Java for something (like Minecraft), at least disable the Java browser plugin. If you’re not sure whether you need Java, you probably don’t. Are any browser plugins out-of-date? – Visit Mozilla’s Plugin Check website (yes, it also works in other browsers, not just Firefox) and see if you have any critically vulnerable plugins installed. If you do, ensure you update them — or uninstall them. You probably don’t need older plugins like QuickTime or RealPlayer installed on your computer, although Flash is still widely used. Are your web browser and operating system set to automatically update? – You should be installing updates for Windows via Windows Update when they appear. Modern web browsers are set to automatically update, so they should be fine — unless you went out of your way to disable automatic updates. Using out-of-date web browsers and Windows versions is dangerous. Are you being careful about what you run? – Watch out when downloading software to ensure you don’t accidentally click sketchy advertisements and download harmful software. Avoid pirated software that may be full of malware. Don’t run programs from email attachments. Be careful about what you run and where you get it from in general. If you can’t figure out how the malware arrived because everything looks okay, there’s not much more you can do. Just try to follow proper security practices. You may also want to keep an extra-close eye on your credit card statement for a while if you did any online-shopping recently. As so much malware is now related to organized crime, credit card numbers are a popular target.     

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• SQL SERVER – Weekly Series – Memory Lane – #031

  - by Pinal Dave

  Here is the list of selected articles of SQLAuthority.com across all these years. Instead of just listing all the articles I have selected a few of my most favorite articles and have listed them here with additional notes below it. Let me know which one of the following is your favorite article from memory lane. 2007 Find Table without Clustered Index – Find Table with no Primary Key Clustered index is very important concept for any table. They impact the performance very heavily. Here is a quick script to find tables without a clustered index. Replace TEXT with VARCHAR(MAX) – Stop using TEXT, NTEXT, IMAGE Data Types Question: “Is VARCHAR (MAX) big enough to store the TEXT field?” Answer: “Yes, VARCHAR(MAX) is big enough to accommodate TEXT field. TEXT, NTEXT and IMAGE data types of SQL Server 2000 will be deprecated in a future version of SQL Server, SQL Server 2005 provides backward compatibility to data types but it is recommended to use new data types which are VARHCAR (MAX), NVARCHAR (MAX) and VARBINARY (MAX).” Limiting Result Sets by Using TABLESAMPLE – Examples Introduced in SQL Server 2005, TABLESAMPLE allows you to extract a sampling of rows from a table in the FROM clause. The rows retrieved are random and they are are not in any order. This sampling can be based on a percentage of number of rows. You can use TABLESAMPLE when only a sampling of rows is necessary for the application instead of a full result set. User Defined Functions (UDF) Limitations UDF have its own advantage and usage but in this article we will see the limitation of UDF. Things UDF can not do and why Stored Procedure are considered as more flexible then UDFs. Stored Procedure are more flexibility then User Defined Functions(UDF). However, this blog post is a good read to know what are the limitations of UDF. Change Database Compatible Level – Backward Compatibility For a long time SQL Server stayed on the compatibility level of 80 which is of SQL Server 2000. However, as soon as SQL Server 2005 introduced the issue of compatibility was quite a major issue. Since that time MS has been releasing the versions at every 2-3 years, changing compatibility is a ever popular topic. In this blog post, we learn how we can do the same using T-SQL. We can also do the same using SSMS and here is the blog post for the same: Change Database Compatible Level – Backward Compatibility – Part 2 – Management Studio. Constraint on VARCHAR(MAX) Field To Limit It Certain Length How can I limit the VARCHAR(MAX) field with maximum length of 12500 characters only. His Question was valid as our application was allowed 12500 characters. First of all – this requirement is bit strange but if someone wants to do the same, they can do it as described in this blog post. 2008 UNPIVOT Table Example Understanding UNPIVOT can be very complicated at times. In this blog post, I have attempted to explain the same concept in very simple words. Create Default Constraint Over Table Column A simple straight to script blog post – I still use this blog quite many times for my own reference. UDF – Get the Day of the Week Function It took me 4 iteration to find this very simple function which can immediately get the day of the week in a single line. 2009 Find Hostname and Current Logged In User Name There are two tricks listed in this blog post where users can find out the hostname and current logged user name immediately and very easily. Interesting Observation of Logon Trigger On All Servers When I was doing a project, I made an interesting observation of executing a logon trigger multiple times. It was absolutely unexpected for me! As I was logging only once, naturally, I was expecting the entry only once. However, it did it multiple times on different threads – indeed an eccentric phenomenon at first sight! Difference Between Candidate Keys and Primary Key One needs to be very careful in selecting the Primary Key as an incorrect selection can adversely impact the database architect and future normalization. For a Candidate Key to qualify as a Primary Key, it should be Non-NULL and unique in any domain. I have observed quite often that Primary Keys are seldom changed. I would like to have your feedback on not changing a Primary Key. Create Multiple Filegroup For Single Database Why should one create multiple file group for any database and what are the advantages of the same. In this blog post, I explain the same in detail. List All Objects Created on All Filegroups in Database In this blog post we discuss the essential question – “How can I find which object belongs to which filegroup. Is there any way to know this?” 2010 DATE and TIME in SQL Server 2008 When DATE is converted to DATETIME it adds the of midnight. When TIME is converted to DATETIME it adds the date of 1900 and it is something one wants to consider if you are going to run scripts from SQL Server 2008 to earlier version with CONVERT. Disabled Index and Update Statistics If you do not need a nonclustered index, I suggest you to drop it as keeping them disabled is an overhead on your system. This is because every time the statistics are updated for system all the statistics for disabled indexes are also updated. Precision of SMALLDATETIME – A 1 Minute Precision The precision of the datatype SMALLDATETIME is 1 minute. It discards the seconds by rounding up or rounding down any seconds greater than zero. 2011 Getting Columns Headers without Result Data – SET FMTONLY ON SET FMTONLY ON returns only metadata to the client. It can be used to test the format of the response without actually running the query. When this setting is ON the resultset only have headers of the results but no data. Copy Database from Instance to Another Instance – Copy Paste in SQL Server SQL Server has a feature which copy database from one database to another database and it can be automated as well using SSIS. Make sure you have SQL Server Agent Turned on as this feature will create a job. Puzzle – SELECT * vs SELECT COUNT(*) If you have ever wondered SELECT * gives error when executed alone but SELECT COUNT(*) does not. Why? in that case, you should read this blog post. Creating All New Database with Full Recovery Model This blog post is very based on very interesting story where the user wants to do something by default for every single new database created. Model database is a secret weapon which should be used very carefully and with proper evalution. If used carefully this can be a very much beneficiary when we need a newly created database behave in certain fashion. 2012 In year 2012 I had two interesting series ran on the blog. If there is no fun in learning, the learning becomes a burden. For the same reason, I had decided to build a three part quiz around SEQUENCE. The quiz was to identify the next value of the sequence. I encourage all of you to take part in this fun quiz. Guess the Next Value – Puzzle 1 Guess the Next Value – Puzzle 2 Guess the Next Value – Puzzle 3 Can anyone remember their final day of schooling?  This is probably a silly question because – of course you can!  Many people mark this as the most exciting, happiest day of their life.  It marks the end of testing, the end of following rules set by teachers, and the beginning of finally being able to earn money and work in your chosen field. Read five part series on developer training subject Developer Training - Importance and Significance - Part 1 Developer Training – Employee Morals and Ethics – Part 2 Developer Training – Difficult Questions and Alternative Perspective - Part 3 Developer Training – Various Options for Developer Training – Part 4 Developer Training – A Conclusive Summary- Part 5 Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: Memory Lane, PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology

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• Why people don't patch and upgrade?!?

  - by Mike Dietrich

  Discussing the topic "Why Upgrade" or "Why not Upgrade" is not always fun. Actually the arguments repeat from customer to customer. Typically we hear things such as: A PSU or Patch Set introduces new bugs A new PSU or Patch Set introduces new features which lead to risk and require application verification  Patching means risk Patching changes the execution plans Patching requires too much testing Patching is too much work for our DBAs Patching costs a lot of money and doesn't pay out And to be very honest sometimes it's hard for me to stay calm in such discussions. Let's discuss some of these points a bit more in detail. A PSU or Patch Set introduces new bugsWell, yes, that is true as no software containing more than some lines of code is bug free. This applies to Oracle's code as well as too any application or operating system code. But first of all, does that mean you never patch your OS because the patch may introduce new flaws? And second, what is the point of saying "it introduces new bugs"? Does that mean you will never get rid of the mean issues we know about and we fixed already? Scroll down from MOS Note:161818.1 to the patch release you are on, no matter if it's 10.2.0.4 or 11.2.0.3 and check for the Known Issues And Alerts.Will you take responsibility to know about all these issues and refuse to upgrade to 11.2.0.4? I won't. A new PSU or Patch Set introduces new featuresOk, we can discuss that. Offering new functionality within a database patch set is a dubious thing. It has advantages such as in 11.2.0.4 where we backported Database Redaction to. But this is something you will only use once you have an Advanced Security license. I interpret that statement I've heard quite often from customers in a different way: People don't want to get surprises such as new behaviour. This certainly gives everybody a hard time. And we've had many examples in the past (SESSION_CACHED_CURSROS in 10.2.0.4,  _DATAFILE_WRITE_ERRORS_CRASH_INSTANCE in 11.2.0.2 and others) where those things weren't documented, not even in the README. Thanks to many friends out there I learned about those as well. So new behaviour is the topic people consider as risky - not really new features. And just to point this out: A PSU never brings in new features or new behaviour by definition! Patching means riskDoes it really mean risk? Yes, there were issues in the past (and sometimes in the present as well) where a patch didn't get installed correctly. But personally I consider it way more risky to not patch. Keep that in mind: The day Oracle publishes an PSU (or CPU) containing security fixes all the great security experts out there go public with their findings as well. So from that day on even my grandma can find out about those issues and try to attack somebody. Now a lot of people say: "My database does not face the internet." And I will answer: "The enemy is sitting already behind your firewalls. And knows potentially about these things." My statement: Not patching introduces way more risk to your environment than patching. Seriously! Patching changes the execution plansDo they really? I agree - there's a very small risk for this happening with Patch Sets. But not with PSUs or CPUs as they contain no optimizer fixes changing behaviour (but they may contain fixes curing wrong-query-result-bugs). But what's the point of a changing execution plan? In Oracle Database 11g it is so simple to be prepared. SQL Plan Management is a free EE feature - so once that occurs you'll put the plan into the Plan Baseline. Basta! Yes, you wouldn't like to get such surprises? Than please use the SQL Performance Analyzer (SPA) from Real Application Testing and you'll detect that easily upfront in minutes. And not to forget this, a plan change can also be very positive!Yes, there's a little risk with a database patchset - and we have many possibilites to detect this before patching. Patching requires too much testingWell, does it really? I have seen in the past 12 years how people test. There are very different efforts and approaches on this. I have seen people spending a hell of money on licenses or on project team staffing. And I have seen people sailing blindly without any tests just going the John-Wayne-approach.Proper tools will allow you to test easily without too much efforts. See the paragraph above. We have used Real Application Testing in so many customer projects reducing the amount of work spend on testing by over 50%. But apart from that at some point you will have to stop testing. If you don't you'll get lost and you'll burn money. There's no 100% guaranty. You will have to deal with a little risk as reaching the final 5% of certainty will cost you the same as it did cost to reach 95%. And doing this will lead to abnormal long product cycles that you'll run behind forever. And this will cost even more money. Patching is too much work for our DBAsPatching is a lot of work. I agree. And it's no fun work. It's boring, annoying. You don't learn much from that. That's why you should try to automate this task. Use the Database's Lifecycle Management Pack. And don't cry about the fact that it costs money. Yes it does. But it will ease the process and you'll save a lot of costs as you don't waste your valuable time with patching. Or use Oracle Database 12c Oracle Multitenant and patch either by unplug/plug or patch an entire container database with all PDBs with one patch in one task. We have customer reference cases proofing it saved them 75% of time, effort and cost since they've used Lifecycle Management Pack. So why don't you use it? Patching costs a lot of money and doesn't pay outWell, see my statements in the paragraph above. And it pays out as flying with a database with 100 known critical flaws in it which are already fixed by Oracle (such as in the Oct 2013 PSU for Oracle Database 12c) will cost ways more in case of failure or even data loss. Bet with me? Let me finally ask you some questions. What cell phone are you using and which OS does it run? Do you have an iPhone 5 and did you upgrade already to iOS 7.0.3? I've just encountered on mine that the alarm (which I rely on when traveling) has gotten now a dependency on the physical switch "sound on/off". If it is switched to "off" physically the alarm rings "silently". What a wonderful example of a behaviour change coming in with a patch set. Will this push you to stay with iOS5 or iOS6? No, because those have security flaws which won't be fixed anymore. What browser are you surfing with? Do you use Mozilla 3.6? Well, congratulations to all the hackers. It will be easy for them to attack you and harm your system. I'd guess you have the auto updater on.  Same for Google Chrome, Safari, IE. Right? -Mike The T.htmtableborders, .htmtableborders td, .htmtableborders th {border : 1px dashed lightgrey ! important;} html, body { border: 0px; } body { background-color: #ffffff; } img, hr { cursor: default }

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• Exception Handling And Other Contentious Political Topics

  - by Justin Jones

  So about three years ago, around the time of my last blog post, I promised a friend I would write this post. Keeping promises is a good thing, and this is my first step towards easing back into regular blogging. I fully expect him to return from Pennsylvania to buy me a beer over this. However, it’s been an… ahem… eventful three years or so, and blogging, unfortunately, got pushed to the back burner on my priority list, along with a few other career minded activities. Now that the personal drama of the past three years is more or less resolved, it’s time to put a few things back on the front burner. What I consider to be proper exception handling practices is relatively well known these days. There are plenty of blog posts out there already on this topic which more or less echo my opinions on this topic. I’ll try to include a few links at the bottom of the post. Several years ago I had an argument with a co-worker who posited that exceptions should be caught at every level and logged. This might seem like sanity on the surface, but the resulting error log looked something like this: Error: System.SomeException Followed by small stack trace. Error: System.SomeException Followed by slightly bigger stack trace. Error: System.SomeException Followed by slightly bigger stack trace. Error: System.SomeException Followed by slightly bigger stack trace. Error: System.SomeException Followed by slightly bigger stack trace. Error: System.SomeException Followed by slightly bigger stack trace. Error: System.SomeException Followed by slightly bigger stack trace. Error: System.SomeException Followed by slightly bigger stack trace.   These were all the same exception. The problem with this approach is that the error log, if you run any kind of analytics on in, becomes skewed depending on how far up the stack trace your exception was thrown. To mitigate this problem, we came up with the concept of the “PreLoggedException”. Basically, we would log the exception at the very top level and subsequently throw the exception back up the stack encapsulated in this pre-logged type, which our logging system knew to ignore. Now the error log looked like this: Error: System.SomeException Followed by small stack trace. Much cleaner, right? Well, there’s still a problem. When your exception happens in production and you go about trying to figure out what happened, you’ve lost more or less all context for where and how this exception was thrown, because all you really know is what method it was thrown in, but really nothing about who was calling the method or why. What gives you this clue is the entire stack trace, which we’re losing here. I believe that was further mitigated by having the logging system pull a system stack trace and add it to the log entry, but what you’re actually getting is the stack for how you got to the logging code. You’re still losing context about the actual error. Not to mention you’re executing a whole slew of catch blocks which are sloooooooowwwww……… In other words, we started with a bad idea and kept band-aiding it until it didn’t suck quite so bad. When I argued for not catching exceptions at every level but rather catching them following a certain set of rules, my co-worker warned me “do yourself a favor, never express that view in any future interviews.” I suppose this is my ultimate dismissal of that advice, but I’m not too worried. My approach for exception handling follows three basic rules: Only catch an exception if 1. You can do something about it. 2. You can add useful information to it. 3. You’re at an application boundary. Here’s what that means: 1. Only catch an exception if you can do something about it. We’ll start with a trivial example of a login system that uses a file. Please, never actually do this in production code, it’s just concocted example. So if our code goes to open a file and the file isn’t there, we get a FileNotFound exception. If the calling code doesn’t know what to do with this, it should bubble up. However, if we know how to create the file from scratch we can create the file and continue on our merry way. When you run into situations like this though, What should really run through your head is “How can I avoid handling an exception at all?” In this case, it’s a trivial matter to simply check for the existence of the file before trying to open it. If we detect that the file isn’t there, we can accomplish the same thing without having to handle in in a catch block. 2. Only catch an exception if you can do something about it. Continuing with the poorly thought out file based login system we contrived in part 1, if the code calls a Login(…) method and the FileNotFound exception is thrown higher up the stack, the code that calls Login must account for a FileNotFound exception. This is kind of counterintuitive because the calling code should not need to know the internals of the Login method, and the data file is an implementation detail. What makes more sense, assuming that we didn’t implement any of the good advice from step 1, is for Login to catch the FileNotFound exception and wrap it in a new exception. For argument’s sake we’ll say LoginSystemFailureException. (Sorry, couldn’t think of anything better at the moment.) This gives us two stack traces, preserving the original stack trace in the inner exception, and also is much more informative to the calling code. 3. Only catch an exception if you’re at an application boundary. At some point we have to catch all the exceptions, even the ones we don’t know what to do with. WinForms, ASP.Net, and most other UI technologies have some kind of built in mechanism for catching unhandled exceptions without fatally terminating the application. It’s still a good idea to somehow gracefully exit the application in this case if possible though, because you can no longer be sure what state your application is in, but nothing annoys a user more than an application just exploding. These unhandled exceptions need to be logged, and this is a good place to catch them. Ideally you never want this option to be exercised, but code as though it will be. When you log these exceptions, give them a “Fatal” status (e.g. Log4Net) and make sure these bugs get handled in your next release. That’s it in a nutshell. If you do it right each exception will only get logged once and with the largest stack trace possible which will make those 2am emergency severity 1 debugging sessions much shorter and less frustrating. Here’s a few people who also have interesting things to say on this topic:  http://blogs.msdn.com/b/ericlippert/archive/2008/09/10/vexing-exceptions.aspx http://www.codeproject.com/Articles/9538/Exception-Handling-Best-Practices-in-NET I know there’s more but I can’t find them at the moment.

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• Attaching a Command to the WP7 Application Bar.

  - by mbcrump

  One of the biggest problems that I’ve seen with people creating WP7 applications is how do you bind the application bar to a Relay Command. If your using MVVM then this is particular important. Let’s examine the code that one might add to start with.  <phone:PhoneApplicationPage.ApplicationBar> <shell:ApplicationBar IsVisible="True" IsMenuEnabled="True"> <shell:ApplicationBarIconButton x:Name="appbar_button1" IconUri="/icons/appbar.questionmark.rest.png" Text="About"> <i:Interaction.Triggers> <i:EventTrigger EventName="Click"> <GalaSoft_MvvmLight_Command:EventToCommand Command="{Binding DisplayAbout, Mode=OneWay}" /> </i:EventTrigger> </i:Interaction.Triggers> </shell:ApplicationBarIconButton> <shell:ApplicationBar.MenuItems> <shell:ApplicationBarMenuItem x:Name="menuItem1" Text="MenuItem 1"></shell:ApplicationBarMenuItem> <shell:ApplicationBarMenuItem x:Name="menuItem2" Text="MenuItem 2"></shell:ApplicationBarMenuItem> </shell:ApplicationBar.MenuItems> </shell:ApplicationBar> </phone:PhoneApplicationPage.ApplicationBar> Everything looks right. But we quickly notice that we have a squiggly line under our Interaction.Triggers. The problem is that the object is not a FrameworkObject. This same code would have worked perfect if this were a normal button. OK. Point has been proved. Let’s make the ApplicationBar support Commands. So, go ahead and create a new project using MVVM Light. If you want to check out the source and work along side this tutorial then click here.  7 Easy Steps to have binding on the Application Bar using MVVM Light (I might add that you don’t have to use MVVM Light to get this functionality, I just prefer it.) 1) Download MVVM Light if you don’t already have it and install the project templates. It is available at http://mvvmlight.codeplex.com/. 2) Click File-New Project and navigate to Silverlight for Windows Phone. Make sure you use the MVVM Light (WP7) Template. 3) Now that we have our project setup and ready to go let’s download a wrapper created by Nicolas Humann here, it is called Phone7.Fx. After you download it then extract it somewhere that you can find it. This wrapper will make our application bar/menu item bindable. 4) Right click References inside your WP7 project and add the .dll file to your project. 5) In your MainPage.xaml you will need to add the proper namespace to it. Don’t forget to build your project afterwards. xmlns:Preview="clr-namespace:Phone7.Fx.Preview;assembly=Phone7.Fx.Preview" 6) Now you can add the BindableAppBar to your MainPage.xaml with a few lines of code.  <Preview:BindableApplicationBar x:Name="AppBar" BarOpacity="1.0" > <Preview:BindableApplicationBarIconButton Command="{Binding DisplayAbout}" IconUri="/icons/appbar.questionmark.rest.png" Text="About" /> <Preview:BindableApplicationBar.MenuItems> <Preview:BindableApplicationBarMenuItem Text="Settings" Command="{Binding InputBox}" /> </Preview:BindableApplicationBar.MenuItems> </Preview:BindableApplicationBar> So your final MainPage.xaml will look similar to this: NOTE: The AppBar will be located inside of the Grid using this wrapper.   <!--LayoutRoot contains the root grid where all other page content is placed--> <Grid x:Name="LayoutRoot" Background="Transparent"> <Grid.RowDefinitions> <RowDefinition Height="Auto" /> <RowDefinition Height="*" /> </Grid.RowDefinitions> <!--TitlePanel contains the name of the application and page title--> <StackPanel x:Name="TitlePanel" Grid.Row="0" Margin="24,24,0,12"> <TextBlock x:Name="ApplicationTitle" Text="{Binding ApplicationTitle}" Style="{StaticResource PhoneTextNormalStyle}" /> <TextBlock x:Name="PageTitle" Text="{Binding PageName}" Margin="-3,-8,0,0" Style="{StaticResource PhoneTextTitle1Style}" /> </StackPanel> <!--ContentPanel - place additional content here--> <Grid x:Name="ContentGrid" Grid.Row="1"> <TextBlock Text="{Binding Welcome}" Style="{StaticResource PhoneTextNormalStyle}" HorizontalAlignment="Center" VerticalAlignment="Center" FontSize="40" /> </Grid> <Preview:BindableApplicationBar x:Name="AppBar" BarOpacity="1.0" > <Preview:BindableApplicationBarIconButton Command="{Binding DisplayAbout}" IconUri="/icons/appbar.questionmark.rest.png" Text="About" /> <Preview:BindableApplicationBar.MenuItems> <Preview:BindableApplicationBarMenuItem Text="Settings" Command="{Binding InputBox}" /> </Preview:BindableApplicationBar.MenuItems> </Preview:BindableApplicationBar> </Grid> 7) Let’s go ahead and create the RelayCommands and write them up to a MessageBox by editing our MainViewModel.cs file. public class MainViewModel : ViewModelBase { public string ApplicationTitle { get { return "MVVM LIGHT"; } } public string PageName { get { return "My page:"; } } public string Welcome { get { return "Welcome to MVVM Light"; } } public RelayCommand DisplayAbout { get; private set; } public RelayCommand InputBox { get; private set; } /// <summary> /// Initializes a new instance of the MainViewModel class. /// </summary> public MainViewModel() { if (IsInDesignMode) { // Code runs in Blend --> create design time data. } else { DisplayAbout = new RelayCommand(() => { MessageBox.Show("About box called!"); }); InputBox = new RelayCommand(() => { MessageBox.Show("settings button called"); }); } } If you run the project now you should get something similar to this (notice the AppBar at the bottom):  Now if you hit the question mark then you will get the following MessageBox: The MenuItem works as well so for Settings: As you can see, its pretty easy to add a Command to the ApplicationBar/MenuItem. If you want to look through the full source code then click here.   Subscribe to my feed

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• Disaster, or Migration?

  - by Rob Farley

  This post is in two parts – technical and personal. And I should point out that it’s prompted in part by this month’s T-SQL Tuesday, hosted by Allen Kinsel. First, the technical: I’ve had a few conversations with people recently about migration – moving a SQL Server database from one box to another (sometimes, but not primarily, involving an upgrade). One question that tends to come up is that of downtime. Obviously there will be some period of time between the old server being available and the new one. The way that most people seem to think of migration is this: Build a new server. Stop people from using the old server. Take a backup of the old server Restore it on the new server. Reconfigure the client applications (or alternatively, configure the new server to use the same address as the old) Make the new server online. There are other things involved, such as testing, of course. But this is essentially the process that people tell me they’re planning to follow. The bit that I want to look at today (as you’ve probably guessed from my title) is the “backup and restore” section. If a SQL database is using the Simple Recovery Model, then the only restore option is the last database backup. This backup could be full or differential. The transaction log never gets backed up in the Simple Recovery Model. Instead, it truncates regularly to stay small. One that’s using the Full Recovery Model (or Bulk-Logged) won’t truncate its log – the log must be backed up regularly. This provides the benefit of having a lot more option available for restores. It’s a requirement for most systems of High Availability, because if you’re making sure that a spare box is up-and-running, ready to take over, then you have to be interested in the logs that are happening on the current box, rather than truncating them all the time. A High Availability system such as Mirroring, Replication or Log Shipping will initialise the spare machine by restoring a full database backup (and maybe a differential backup if available), and then any subsequent log backups. Once the secondary copy is close, transactions can be applied to keep the two in sync. The main aspect of any High Availability system is to have a redundant system that is ready to take over. So the similarity for migration should be obvious. If you need to move a database from one box to another, then introducing a High Availability mechanism can help. By turning on the Full Recovery Model and then taking a backup (so that the now-interesting logs have some context), logs start being kept, and are therefore available for getting the new box ready (even if it’s an upgraded version). When the migration is ready to occur, a failover can be done, letting the new server take over the responsibility of the old, just as if a disaster had happened. Except that this is a planned failover, not a disaster at all. There’s a fine line between a disaster and a migration. Failovers can be useful in patching, upgrading, maintenance, and more. Hopefully, even an unexpected disaster can be seen as just another failover, and there can be an opportunity there – perhaps to get some work done on the principal server to increase robustness. And if I’ve just set up a High Availability system for even the simplest of databases, it’s not necessarily a bad thing. :) So now the personal: It’s been an interesting time recently... June has been somewhat odd. A court case with which I was involved got resolved (through mediation). I can’t go into details, but my lawyers tell me that I’m allowed to say how I feel about it. The answer is ‘lousy’. I don’t regret pursuing it as long as I did – but in the end I had to make a decision regarding the commerciality of letting it continue, and I’m going to look forward to the days when the kind of money I spent on my lawyers is small change. Mind you, if I had a similar situation with an employer, I’d do the same again, but that doesn’t really stop me feeling frustrated about it. The following day I had to fly to country Victoria to see my grandmother, who wasn’t expected to last the weekend. She’s still around a week later as I write this, but her 92-year-old body has basically given up on her. She’s been a Christian all her life, and is looking forward to eternity. We’ll all miss her though, and it’s hard to see my family grieving. Then on Tuesday, I was driving back to the airport with my family to come home, when something really bizarre happened. We were travelling down the freeway, just pulled out to go past a truck (farm-truck sized, not a semi-trailer), when a car-sized mass of metal fell off it. It was something like an industrial air-conditioner, but from where I was sitting, it was just a mass of spinning metal, like something out of a movie (one friend described it as “holidays by Michael Bay”). Somehow, and I’m really don’t know how, the part of it nearest us bounced high enough to clear the car, and there wasn’t even a scratch. We pulled over the check, and I was just thanking God that we’d changed lanes when we had, and that we remained unharmed. I had all kinds of thoughts about what could’ve happened if we’d had something that size land on the windscreen... All this has drilled home that while I feel that I haven’t provided as well for the family as I could’ve done (like by pursuing an expensive legal case), I shouldn’t even consider that I have proper control over things. I get to live life, and make decisions based on what I feel is right at the time. But I’m not going to get everything right, and there will be things that feel like disasters, some which could’ve been in my control and some which are very much beyond my control. The case feels like something I could’ve pursued differently, a disaster that could’ve been avoided in some way. Gran dying is lousy of course. An accident on the freeway would have been awful. I need to recognise that the worst disasters are ones that I can’t affect, and that I need to look at things in context – perhaps seeing everything that happens as a migration instead. Life is never the same from one day to the next. Every event has a before and an after – sometimes it’s clearly positive, sometimes it’s not. I remember good events in my life (such as my wedding), and bad (such as the loss of my father when I was ten, or the back injury I had eight years ago). I’m not suggesting that I know how to view everything from the “God works all things for good” perspective, but I am trying to look at last week as a migration of sorts. Those things are behind me now, and the future is in God’s hands. Hopefully I’ve learned things, and will be able to live accordingly. I’ve come through this time now, and even though I’ll miss Gran, I’ll see her again one day, and the future is bright.

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