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  • ArchBeat Link-o-Rama for 2012-06-01

    - by Bob Rhubart
    Complexity of Social Computing - Is it a Consideration for EA's? | Pat Shepherd blogs.oracle.com Pat Shepherd asks, "Does Enterprise Architecture need to consider Social Computing in its scope?" Who should own the Enterprise Architecture? | Michael Glas blogs.oracle.com "Instead of looking at just who owns the architecture," suggests Michael Glas, "think about what the person/role/organization should do." The Application Architecture Domain | Michael Glas blogs.oracle.com Michael Glas asks—and answers: "As an Enterprise Architect, what do I need to consider when looking at/defining/designing the Application Architecture Domain?" CAP Twelve Years Later: How the "Rules" Have Changed | Eric Brewer www.infoq.com The CAP theorem asserts that any net­worked shared-data system can have only two of three desirable properties. How­ever, by explicitly handling partitions, designers can optimize consistency and availability, thereby achieving some trade-off of all three. Oracle DB with OEM in Amazon Cloud | Dr. Frank Munz www.munzandmore.com Dr. Frank Munz shares a video that screencast that explains "how to create an Oracle DB instance in AWS, how to enable OEM...and how to connect to your cloud instance with a local installation of NetBeans." Sample External Login.jsp page for Oracle Access Manager 11g | Brian Eidelman fusionsecurity.blogspot.com A-Team blogger Brian Eidelman expands on a previous post dealing with configuring OAM 11g to use an externally hosted custom login page. Bay Area Coherence Special Interest Group (BACSIG) Meeting June 7 coherence.oracle.com Date: Thursday, June 7, 2012 Time: 5:30pm – 9:00pm PT Where: Oracle Conference Center Room # 103 350 Oracle Parkway Redwood, Shores, CA Presentations: 6:00 p.m. - Coherence 101, The Evolution of Distributed Caching - Noah Arliss (Oracle) 7:00 p.m. - Optimizing Performance for Oracle Coherence and TopLink Grid at OOCL - Matt Rosen, Leo Limqueco (OOCL) 8:00 p.m. - Oracle Coherence Message Bus - Extreme Performance on Oracle Exalogic - Ballav Bihani (Oracle) Thought for the Day "I can't be left unsupervised." — Ron Wood (Born 06/01/1947 Source: Brainy Quote

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  • Intel fait durer le suspens sur Sandy Bridge en délivrant les informations au compte-gouttes sur la

    Intel fait durer le suspens sur Sandy Bridge En délivrant les informations au compte-gouttes sur la future micro-architecture de ses processeurs Sandy Bridge est le successeur de Nehalem, la micro-architecture utilisée par Intel pour ses processeurs. Bien qu'on en sache encore assez peu sur cette nouvelle technologie, elle fait d'ores et déjà couler beaucoup d'encre. La stratégie de communication d'Intel, qui délivre les informations au compte-gouttes, n'y est certainement pas pour rien. Lors des derniers Intel Developer Forum (IDF) qui vient de s'achever, David Perlmutter - Executive Vice President Intel Architecture Group - a néanmoins laissé filtrer quelques indices :

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  • ArchBeat Link-o-Rama Top 20 for June 17-23, 2012

    - by Bob Rhubart
    The most popular item shared via my social networks for the week of June 17-23, 2012. Simple Made Easy | Rich Hickey InfoQ: Current Trends in Enterprise Mobility Cloud Bursting between AWS and Rackspace | High Scalability A Distributed Access Control Architecture for Cloud Computing Congrats to @MNEMONIC01 on his new book: Oracle WebLogic Server 12c: First Look BI Architecture Master Class for Partners - Oracle Architecture Unplugged Guide to integration architecture | Stephanie Mann Oracle Data Integrator 11g - Faster Files | David Allan Recap: EMEA User Group Leaders Meeting Latvia May 2012 Starting a cluster | Mark Nelson SOA, Cloud & Service Technology Symposium 2012 London - Special Oracle Discount Enterprise 2.0 Conference: Building Social Business | Oracle WebCenter Blog FY13 Oracle PartnerNetworkr Kickoff - Tues June 26, 2012 | @oraclepartners Why should you choose Oracle WebLogic 12c instead of JBoss EAP 6? | Ricardo Ferreira Call for Nominations: Oracle Fusion Middleware Innovation Awards 2012 - Win a free pass to #OOW12 Hibernate4 and Coherence | Rene van Wijk Eclipse and Oracle Fusion Development - Free Virtual Event, July 10th Why building SaaS well means giving up your servers | GigaOM Personas - what, why & how | Mascha van Oosterhout Oracle Public Cloud Architecture | Tyler Jewell Thought for the Day "There is only one thing more painful than learning from experience and that is not learning from experience." — Archibald McLeish (May 7, 1892 – April 20, 1982) Source: SoftwareQuotes.com

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  • Big Data – Buzz Words: What is HDFS – Day 8 of 21

    - by Pinal Dave
    In yesterday’s blog post we learned what is MapReduce. In this article we will take a quick look at one of the four most important buzz words which goes around Big Data – HDFS. What is HDFS ? HDFS stands for Hadoop Distributed File System and it is a primary storage system used by Hadoop. It provides high performance access to data across Hadoop clusters. It is usually deployed on low-cost commodity hardware. In commodity hardware deployment server failures are very common. Due to the same reason HDFS is built to have high fault tolerance. The data transfer rate between compute nodes in HDFS is very high, which leads to reduced risk of failure. HDFS creates smaller pieces of the big data and distributes it on different nodes. It also copies each smaller piece to multiple times on different nodes. Hence when any node with the data crashes the system is automatically able to use the data from a different node and continue the process. This is the key feature of the HDFS system. Architecture of HDFS The architecture of the HDFS is master/slave architecture. An HDFS cluster always consists of single NameNode. This single NameNode is a master server and it manages the file system as well regulates access to various files. In additional to NameNode there are multiple DataNodes. There is always one DataNode for each data server. In HDFS a big file is split into one or more blocks and those blocks are stored in a set of DataNodes. The primary task of the NameNode is to open, close or rename files and directory and regulate access to the file system, whereas the primary task of the DataNode is read and write to the file systems. DataNode is also responsible for the creation, deletion or replication of the data based on the instruction from NameNode. In reality, NameNode and DataNode are software designed to run on commodity machine build in Java language. Visual Representation of HDFS Architecture Let us understand how HDFS works with the help of the diagram. Client APP or HDFS Client connects to NameSpace as well as DataNode. Client App access to the DataNode is regulated by NameSpace Node. NameSpace Node allows Client App to connect to the DataNode based by allowing the connection to the DataNode directly. A big data file is divided into multiple data blocks (let us assume that those data chunks are A,B,C and D. Client App will later on write data blocks directly to the DataNode. Client App does not have to directly write to all the node. It just has to write to any one of the node and NameNode will decide on which other DataNode it will have to replicate the data. In our example Client App directly writes to DataNode 1 and detained 3. However, data chunks are automatically replicated to other nodes. All the information like in which DataNode which data block is placed is written back to NameNode. High Availability During Disaster Now as multiple DataNode have same data blocks in the case of any DataNode which faces the disaster, the entire process will continue as other DataNode will assume the role to serve the specific data block which was on the failed node. This system provides very high tolerance to disaster and provides high availability. If you notice there is only single NameNode in our architecture. If that node fails our entire Hadoop Application will stop performing as it is a single node where we store all the metadata. As this node is very critical, it is usually replicated on another clustered as well as on another data rack. Though, that replicated node is not operational in architecture, it has all the necessary data to perform the task of the NameNode in the case of the NameNode fails. The entire Hadoop architecture is built to function smoothly even there are node failures or hardware malfunction. It is built on the simple concept that data is so big it is impossible to have come up with a single piece of the hardware which can manage it properly. We need lots of commodity (cheap) hardware to manage our big data and hardware failure is part of the commodity servers. To reduce the impact of hardware failure Hadoop architecture is built to overcome the limitation of the non-functioning hardware. Tomorrow In tomorrow’s blog post we will discuss the importance of the relational database in Big Data. Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: Big Data, PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, T SQL

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  • One Week To Go: OTN Architect Day: Cloud Computing

    - by Bob Rhubart
    One week remains until OTN Architect Day: Cloud Computing kicks of at the spectacular Oracle HQ campus in Redwood Shores, CA. The event is free, and there is still time to register. When: Tuesday July 9, 2013 8:30am - 12:30pm Where: Oracle Conference Center350 Oracle Pkwy Redwood City, CA 94065 Register now. It's free! Here's the latest update to the event agenda: 8:30am - 9:00am Registration and Continental Breakfast 9:00am - 9:45am Keynote 21st Century IT | Dr. James Baty VP, Global Enterprise Architecture Program, Oracle Imagine a time long, long ago. A time when servers were certified and dedicated to specific applications, when anything posted on an enterprise web site was from restricted, approved channels, and when we tried to limit the growth of 'dirty' data and storage. Today, applications are services running in the muti-tenant hybrid cloud. Companies beg their customers to tweet them, friend them, and publicly rate their products. And constantly analyzing a deluge of Internet, social and sensor data is the key to creating the next super-successful product, or capturing an evil terrorist. The old IT architecture was planned, dedicated, stable, controlled, with separate and well-defined roles. The new architecture is shared, dynamic, continuous, XaaS, DevOps. This keynote session describes the challenges and opportunities that the new business / IT paradigms present to the IT architecture and architects. 9:45am - 10:30am Technical Session Oracle Cloud: A Case Study in Building a Cloud | Anbu Krishnaswami Enterprise Architect, Oracle Building a Cloud can be challenging thanks to the complex requirements unique to Cloud computing and the massive scale typically associated with Cloud. Cloud providers can take an Infrastructure as a Service (IaaS) approach and build a cloud on virtualized commodity hardware, or they can take the Platform as a Service (PaaS) path, a service-oriented approach based on pre-configured, integrated, engineered systems. This presentation uses the Oracle Cloud itself as a case study in the use of engineered systems, demonstrating how the technical design of engineered systems is leveraged for building PaaS and SaaS Cloud services and a Cloud management infrastructure. The presentation will also explore the principles, patterns, best practices, and architecture views provided in Oracle's Cloud reference architecture. 10:30 am -10:45 am Break 10:45am-11:30am Technical Session Database as a Service | Markus Michalewicz Senior Principal Product Manager Oracle Real Application Clusters (RAC) New applications are now commonly built in a Cloud model, where the database is consumed as a service, and many established business processes are beginning to migrate to database as a service (DBaaS). This adoption of DBaaS is made possible by the availability of new capabilities in the database that enable resource pooling, dynamic resource management, model-based provisioning, metered use, and effective quality-of-service controls. This session will examine the catalog of database services at a large commercial bank to understand how these capabilities are enabling DBaaS for a wide range of needs within the enterprise. 11:30 am - 12:00 pm Panel Q&A Dr. James Baty, Anbu Krishnaswami, and Markus Michalewicz respond to audience questions. Registration is free, but seating is limited, so register now.

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  • One Week To Go: OTN Architect Day: Cloud Computing

    - by Bob Rhubart
    One week remains until OTN Architect Day: Cloud Computing kicks of at the spectacular Oracle HQ campus in Redwood Shores, CA. The event is free, and there is still time to register. When: Tuesday July 9, 2013 8:30am - 12:30pm Where: Oracle Conference Center350 Oracle Pkwy Redwood City, CA 94065 Register now. It's free! Here's the latest update to the event agenda: 8:30am - 9:00am Registration and Continental Breakfast 9:00am - 9:45am Keynote 21st Century IT | Dr. James Baty VP, Global Enterprise Architecture Program, Oracle Imagine a time long, long ago. A time when servers were certified and dedicated to specific applications, when anything posted on an enterprise web site was from restricted, approved channels, and when we tried to limit the growth of 'dirty' data and storage. Today, applications are services running in the muti-tenant hybrid cloud. Companies beg their customers to tweet them, friend them, and publicly rate their products. And constantly analyzing a deluge of Internet, social and sensor data is the key to creating the next super-successful product, or capturing an evil terrorist. The old IT architecture was planned, dedicated, stable, controlled, with separate and well-defined roles. The new architecture is shared, dynamic, continuous, XaaS, DevOps. This keynote session describes the challenges and opportunities that the new business / IT paradigms present to the IT architecture and architects. 9:45am - 10:30am Technical Session Oracle Cloud: A Case Study in Building a Cloud | Anbu Krishnaswami Enterprise Architect, Oracle Building a Cloud can be challenging thanks to the complex requirements unique to Cloud computing and the massive scale typically associated with Cloud. Cloud providers can take an Infrastructure as a Service (IaaS) approach and build a cloud on virtualized commodity hardware, or they can take the Platform as a Service (PaaS) path, a service-oriented approach based on pre-configured, integrated, engineered systems. This presentation uses the Oracle Cloud itself as a case study in the use of engineered systems, demonstrating how the technical design of engineered systems is leveraged for building PaaS and SaaS Cloud services and a Cloud management infrastructure. The presentation will also explore the principles, patterns, best practices, and architecture views provided in Oracle's Cloud reference architecture. 10:30 am -10:45 am Break 10:45am-11:30am Technical Session Database as a Service | Markus Michalewicz Senior Principal Product Manager Oracle Real Application Clusters (RAC) New applications are now commonly built in a Cloud model, where the database is consumed as a service, and many established business processes are beginning to migrate to database as a service (DBaaS). This adoption of DBaaS is made possible by the availability of new capabilities in the database that enable resource pooling, dynamic resource management, model-based provisioning, metered use, and effective quality-of-service controls. This session will examine the catalog of database services at a large commercial bank to understand how these capabilities are enabling DBaaS for a wide range of needs within the enterprise. 11:30 am - 12:00 pm Panel Q&A Dr. James Baty, Anbu Krishnaswami, and Markus Michalewicz respond to audience questions. Registration is free, but seating is limited, so register now.

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  • ArchBeat Link-o-Rama for 2012-06-21

    - by Bob Rhubart
    Software Architects Need Not Apply | Dustin Marx "I think there is a place for software architecture," says Dustin Marx, "but a portion of our fellow software architects have harmed the reputation of the discipline." For another angle on this subject, check out Out of the Tower, Into the Trenches from the Nov/Dec edition of Oracle Magazine. Oracle Data Integrator 11g - Faster Files | David Allan David Allan illustrates "a big step for regular file processing on the way to super-charging big data files using Hadoop." 2012 Oracle Fusion Middleware Innovation Awards - Win a FREE Pass to Oracle OpenWorld 2012 in SF Share your use of Oracle Fusion Middleware solutions and how they help your organization drive business innovation. You just might win a free pass to Oracle Openworld 2012 in San Francisco. Deadline for submissions in July 17, 2012. WLST Domain creation using dry-run | Michel Schildmeijer What to do "if you want to browse through your domain to check if settings you want to apply satisfy your requirements." Cloud opens up new vistas for service orientation at Netflix | Joe McKendrick "Many see service oriented architecture as laying the groundwork for cloud. But at one well-known company, cloud has instigated the move to SOA." How to avoid the Portlet Skin mismatch | Martin Deh Detailed how-to from WebCenter A-Team blogger Martin Deh. Internationalize WebCenter Portal - Content Presenter | Stefan Krantz Stefan Krantz explains "how to get Content Presenter and its editorials to comply with the current selected locale for the WebCenter Portal session." Oracle Public Cloud Architecture | Tyler Jewell Tyler Jewell discusses the multi-tenancy model and elasticity solution implemented by Oracle Cloud in this QCon presentation. A Distributed Access Control Architecture for Cloud Computing The authors of this InfoQ article discuss a distributed architecture based on the principles from security management and software engineering. Thought for the Day "Let us change our traditional attitude to the construction of programs. Instead of imagining that our main task is to instruct a computer what to to, let us concentrate rather on explaining to human beings what we want a computer to do." — Donald Knuth Source: Quotes for Software Engineers

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  • How can I create an executable to run on a certain processor architecture (instead of certain OS)?

    - by CrazyJugglerDrummer
    So I take my C++ program in Visual studio, compile, and it'll spit out a nice little EXE file. But EXEs will only run on windows, and I hear a lot about how C/C++ compiles into assembly language, which is runs directly on a processor. The EXE runs with the help of windows, or I could have a program that makes an executable that runs on a mac. But aren't I compiling C++ code into assembly language, which is processor specific? My Insights: I'm guessing I'm probably not. I know there's an Intel C++ compiler, so would it make processor-specific assembly code? EXEs run on windows, so they advantage of tons of things already set up, from graphics packages to the massive .NET framework. A processor-specific executable would be literally starting from scratch, with just the instruction set of the processor. Would this executable be a file-type? We could be running windows and open it, but then would control switch to processor only? I assume this executable would be something like an operating system, in that it would have to be run before anything else was booted up, and have only the processor instruction set to "use".

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  • What is(are) currently the best language(s) for modern web site design? Recommendations?

    - by Jereme Hall
    I'm a little out of date, before HTML4 and javascript got AJAXy. Does anyone have opinions about the best tools for web site design? I'd rather avoid ASP and .NET, since I've got a limited budget. This seems like a good time to start fresh. Please keep the replies on the coding recommendations, as I already know how to register a domain name, redirect it, set up Apache. (I could use some opinions on the various Apache flavors)

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  • What benefits can I get upgrading my ASP.NET (Webform) + DAL(EF) + Repository + BLL structure to MVC?

    - by Etienne
    I'm in the process of defining an approach that may best fit our needs for a big web application development. For now, I'm thinking going with an ASP.NET Architecture with a DAL using Entity Framework, a Repository concept to not access DAL directly from BLL and a BLL that call the repository and make every manipulations necessary to prepare data to push in a presentation layer (.aspx files). I don't plan to use ASP.Net controls and prefer to keep things simple and lightweight using plain html, jQuery UI controls and do most of the server calls with jQuery Ajax. Sometimes, when needed, I plan to use handlers (.ashx) to call BLL methods that will return JSON or HTML to client for dynamic stuff. My solution also has a test project that Mock the Repository with in-memory data to not repose on database for testing BLL methods... It may be usefull to add that we will build a big application over this architecture with hundreds of tables and store procedures with a lot of reading and writing to database. My question is, having this architecture in mind, Is there any evident advantages that I can obtain by using an MVC3 project instead of the described architecture base on Webform? Do you see any problem in this architecture that may cause us problem during the next steps of development? I know the MVC pattern for using it in others projects with Django... but the Microsoft MVC implementation look so much more complex and verbose than Django MVC and it's why I'm hesitating (or waiting for a little push?) right now before jumping into it... We are in a real project with deadlines and don't want to slow the development process without any real benefits.

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  • Does Python/Scipy have a firls( ) replacement (i.e. a weighted, least squares, FIR filter design)?

    - by delicasso
    I am porting code from Matlab to Python and am having trouble finding a replacement for the firls( ) routine. It is used for, least-squares linear-phase Finite Impulse Response (FIR) filter design. I looked at scipy.signal and nothing there looked like it would do the trick. Of course I was able to replace my remez and freqz algorithsm, so that's good. On one blog I found an algorithm that implemented this filter without weighting, but I need one with weights. Thanks, David

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  • how to get the size of a C global array into an assembly program written for the avr architecture co

    - by johannes
    I have a .c file with the following uint8_t buffer[32] I have a .S file where I want to do the following cpi r29, buffer+sizeof(buffer) The second argument for cpi muste be an imidiate value not a location. But unfortunetly sizeof() is a c operator. Both files, are getting compiled to seperate object files and linked afterwards. If I do avr-objdump -x file.c. Amongst other things, I get the size of the buffer. So it is already available in the object file. How do I access the size of the buffer in my assembly file at compile time?

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  • How do I turn off a custom IValueConverter at design time?

    - by Jonathan Allen
    How do I turn off a custom IValueConverter at design time? Basically I want to write this: Public Class MethodBinder Implements IValueConverter Public Function Convert(ByVal value As Object, ByVal targetType As System.Type, ByVal parameter As Object, ByVal culture As CultureInfo) As Object Implements IValueConverter.Convert If [DESIGN_TIME] Then Return Nothing If value IsNot Nothing Then Return CallByName(value, CStr(parameter), CallType.Method) Return Nothing End Function Public Function ConvertBack(ByVal value As Object, ByVal targetType As System.Type, ByVal parameter As Object, ByVal culture As CultureInfo) As Object Implements IValueConverter.ConvertBack Throw New NotSupportedException End Function End Class

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  • Loose Coupling and UX Patterns for Applications Integrations

    - by ultan o'broin
    I love that software architecture phrase loose coupling. There’s even a whole book about it. And, if you’re involved in enterprise methodology you’ll know just know important loose coupling is to the smart development of applications integrations too. Whether you are integrating offerings from the Oracle partner ecosystem with Fusion apps or applications coexistence scenarios, loose coupling enables the development of scalable, reliable, flexible solutions, with no second-guessing of technology. Another great book Enterprise Integration Patterns: Designing, Building, and Deploying Messaging Solutions tells us about loose coupling benefits of reducing the assumptions that integration parties (components, applications, services, programs, users) make about each other when they exchange information. Eliminating assumptions applies to UI development too. The days of assuming it’s enough to hard code a UI with linking libraries called code on a desktop PC for an office worker are over. The book predates PaaS development and SaaS deployments, and was written when web services and APIs were emerging. Yet it calls out how using middleware as an assumptions-dissolving technology “glue" is central to applications integration. Realizing integration design through a set of middleware messaging patterns (messaging in the sense of asynchronously communicating data) that enable developers to meet the typical business requirements of enterprises requiring integrated functionality is very Fusion-like. User experience developers can benefit from the loose coupling approach too. User expectations and work styles change all the time, and development is now about integrating SaaS through PaaS. Cloud computing offers a virtual pivot where a single source of truth (customer or employee data, for example) can be experienced through different UIs (desktop, simplified, or mobile), each optimized for the context of the user’s world of work and task completion. Smart enterprise applications developers, partners, and customers use design patterns for user experience integration benefits too. The Oracle Applications UX design patterns (and supporting guidelines) enable loose coupling of the optimized UI requirements from code. Developers can get on with the job of creating integrations through web services, APIs and SOA without having to figure out design problems about how UIs should work. Adding the already user proven UX design patterns (and supporting guidelines to your toolkit means ADF and other developers can easily offer much more than just functionality and be super productive too. Great looking application integration touchpoints can be built with our design patterns and guidelines too for a seamless applications UX. One of Oracle’s partners, Innowave Technologies used loose coupling architecture and our UX design patterns to create an integration for a customer that was scalable, cost effective, fast to develop and kept users productive while paving a roadmap for customers to keep pace with the latest UX designs over time. Innowave CEO Basheer Khan, a Fusion User Experience Advocate explains how to do it on the Usable Apps blog.

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  • UI design for screen which has number of data entry textFields.

    - by shilpa
    Hi all, my app is an e-commerce application. During the checkout process, I have "recipient" and "credit card" screens. In the recipient screen, there are number of fields for address entry, which makes it very clumsy. Same in the case of the credit card screen, where the user is asked to enter their credit card info and billing address. Can anyone suggest how to design these two pages?

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  • What's the best practice or design pattern for user registration ?

    - by Space Cracker
    We have a big portal that needs user registration to allow them use its services. It's already done in .NET and SOL Server 2005. we are in the phase now of discovering all the problems of the current registration system to build a new robust flexible one that can be extended easily and can be more usable for all services. Could any help me find best practices and design patterns to help me rebuild this using good architectural practices?

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  • Where are the network boundaries in the Java Connector Architecture (JCA)?

    - by Laird Nelson
    I am writing a JCA resource adapter. I'm also, as I go, trying to fully understand the connection management portion of the JCA specification. As a thought experiment, pretend that the only client of this adapter will be a Swing Java Application Client located on a different machine. Also assume that the resource adapter will communicate with its "enterprise information system" (EIS) over the network as well. As I understand the JCA specification, the .rar file is deployed to the application server. The application server creates the .rar file's implementation of the ManagedConnectionFactory interface. It then asks it to produce a connection factory, which is the opaque object that is deployed to JNDI for the user to use to obtain a connection to the resource. (In the case of JDBC, the connection factory is a javax.sql.DataSource.) It is a requirement that the connection factory retain a reference to the application-server-supplied ConnectionManager, which, in turn, is required to be Serializable. This makes sense--in order for the connection factory to be stored in JNDI, it must be serializable, and in order for it to keep a reference to the ConnectionManager, the ConnectionManager must also be serializable. So fine, this little object graph gets installed in the application client's JNDI tree. This is where I start to get queasy. Is the ConnectionManager--the piece supplied by the application server that is supposed to handle connection management, sharing, pooling, etc.--wholly present on the client at this point? One of its jobs is to create ManagedConnection instances, and a ManagedConnection is not required to be Serializable, and the user connection handles it vends are also not required to be Serializable. That suggests to me that the whole connection pooling machinery is shipped wholesale to the application client and stuffed into its JNDI tree. Does this all mean that JCA interactions from the client side bypass the server-side componentry of the application server? Where are the network boundaries in the JCA API?

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  • SQL query - choosing 'last updated' record in a group, better db design?

    - by Jimmy
    Hi, Let's say I have a MySQL database with 3 tables: table 1: Persons, with 1 column ID (int) table 2: Newsletters, with 1 column ID (int) table 3: Subscriptions, with columns Person_ID (int), Newsletter_ID (int), Subscribed (bool), Updated (Datetime) Subscriptions.Person_ID points to a Person, and Subscription.Newsletter_ID points to a Newsletter. Thus, each person may have 0 or more subscriptions to 0 or more magazines at once. The table Subscriptions will also store the entire history of each person's subscriptions to each newsletter. If a particular Person_ID-Newsletter_ID pair doesn't have a row in the Subscriptions table, then it's equivalent to that pair having a subscription status of 'false'. Here is a sample dataset Persons ID 1 2 3 Newsletters ID 4 5 6 Subscriptions Person_ID Newsletter_ID Subscribed Updated 2 4 true 2010-05-01 3 4 true 2010-05-01 3 5 true 2010-05-10 3 4 false 2010-05-15 Thus, as of 2010-05-16, Person 1 has no subscription, Person 2 has a subscription to Newsletter 4, and Person 3 has a subscription to Newsletter 5. Person 3 had a subscription to Newsletter 4 for a while, but not anymore. I'm trying to do 2 kinds of query. A query that shows everyone's active subscriptions as of query time (we can assume that updated will never be in the future -- thus, this means returning the record with the latest 'updated' value for each Person_ID-Newsletter_ID pair, as long as Subscribed is true (if the latest record for a Person_ID-Newsletter_ID pair has a Subscribed status of false, then I don't want that record returned)). A query that returns all active subscriptions for a specific newsletter - same qualification as in 1. regarding records with 'false' in the Subscribed column. I don't use SQL/databases often enough to tell if this design is good, or if the SQL queries needed would be slow on a database with, say, 1M records in the Subscriptions table. I was using the Visual query builder tool in Visual Studio 2010 but I can't even get the query to return the latest updated record for each Person_ID-Newsletter_ID pair. Is it possible to come up with SQL queries that don't involve using subqueries (presumably because they would become too slow with a larger data set)? If not, would it be a better design to have a separate Subscriptions_History table, and every time a subscription status for a Person_ID-Newsletter-ID pair is added to Subscriptions, any existing record for that pair is moved to Subscriptions_History (that way the Subscriptions table only ever contains the latest status update for any Person_ID-Newsletter_ID pair)? I'm using .net on Windows, so would it be easier (or the same, or harder) to do this kind of queries using Linq? Entity Framework? Thanks!

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