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  • [Ubuntu 10.04] mdadm - Can't get RAID5 Array To Start

    - by Matthew Hodgkins
    Hello, after a power failure my RAID array refuses to start. When I boot I have to sudo mdadm --assemble --force /dev/md0 /dev/sdb1 /dev/sdc1 /dev/sdd1 /dev/sde1 /dev/sdf1 /dev/sdg1 to get mdadm to notice the array. Here are the details (after I force assemble). sudo mdadm --misc --detail /dev/md0: /dev/md0: Version : 00.90 Creation Time : Sun Apr 25 01:39:25 2010 Raid Level : raid5 Used Dev Size : 1465135872 (1397.26 GiB 1500.30 GB) Raid Devices : 6 Total Devices : 6 Preferred Minor : 0 Persistence : Superblock is persistent Update Time : Thu Jun 17 23:02:38 2010 State : active, Not Started Active Devices : 6 Working Devices : 6 Failed Devices : 0 Spare Devices : 0 Layout : left-symmetric Chunk Size : 128K UUID : 44a8f730:b9bea6ea:3a28392c:12b22235 (local to host hodge-fs) Events : 0.1249691 Number Major Minor RaidDevice State 0 8 65 0 active sync /dev/sde1 1 8 81 1 active sync /dev/sdf1 2 8 97 2 active sync /dev/sdg1 3 8 49 3 active sync /dev/sdd1 4 8 33 4 active sync /dev/sdc1 5 8 17 5 active sync /dev/sdb1 mdadm.conf: # by default, scan all partitions (/proc/partitions) for MD superblocks. # alternatively, specify devices to scan, using wildcards if desired. DEVICE partitions /dev/sdb1 /dev/sdb1 # auto-create devices with Debian standard permissions CREATE owner=root group=disk mode=0660 auto=yes # automatically tag new arrays as belonging to the local system HOMEHOST <system> # definitions of existing MD arrays ARRAY /dev/md0 level=raid5 num-devices=6 UUID=44a8f730:b9bea6ea:3a28392c:12b22235 Any help would be appreciated.

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  • jQuery not and classes

    - by Giles B
    Hi Guys, I have 2 anchor links (a.selector) and when one is clicked it has a class applied to it of 'active-arrow' and the click also removes the class of the same name from the other anchor as well as lowering the opacity to 0.2. I then want to have a fade effect when the user hovers over the anchor that doesn't have 'active-arrow' applied to it so that it goes to full opacity when mouseenters and back to 0.2 when mouseleaves. The problem im having is that both .not and :not don't seem to be working as expected, the hover effect works but if I click on the anchor whilst hovering the 'active-arrow' class is applied but when mouseleaves the opacity is faded down to 0.2 again even though the 'active-arrow' class is applied. Also the hover then doesn't work for the other a link which has had 'active-arrow' removed. Bit of a hard one to explain so heres some code that hopefully helps a bit. *//If a.selector doesn't have the class 'active-arrow' then run the hoverFade function* $("a.selector").not(".active-arrow").hoverFade(); //Functions for first element $('a.selector-1').click(function () { $('a.selector-2').removeClass('active-arrow'); //Remove background image from corresponding element $('ul#storage-items-2').fadeOut(1200).addClass('hide'); //Fade out then hide corresponding list $(this).addClass('active-arrow', 'fast'); //Add background image to current element $('ul#storage-items-1').removeClass('hide').fadeIn(1800); //Unhide and fade in the list $('a.selector-2').fadeTo(500, 0.2); //Fade corresponding element $(this).fadeTo(800, 1);//Fade this element to full opacity }); I only included the code for teh first anchor (a.selector-1) as the code for the second anchor is identical but just changes the class names to a.selector-2. Also the hoverFade function is in a seperate file so we can re-use it. jQuery.fn.hoverFade = function() { return this.each(function(){ $(this).hover( function () { $(this).fadeTo(500, 0.8); }, function () { $(this).fadeTo(500, 0.2); }); }); } Each anchor link fades in and fades out a UL as well. Any help is most appreciated Thanks Giles

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  • whats wrong with this ruby hash?

    - by yaya3
    I'm pretty new to ruby, I keep getting the following error: in gem_original_require': ./helpers/navigation.rb:28: odd number list for Hash (SyntaxError) Any help appreciated... module Sinatra::Navigation def navigation @navigation nav = { primary[0] = { :title => "cheddar", :active => false, :children => { { :title => "cheese", :active => false }, { :title => "ham", :active => false } } }, primary[1] = { :title => "gorgonzola", :active => false, :children => { { :title => "What is the cheese?", :active => false }, { :title => "What cheese", :active => false }, { :title => "What does the cheese tell us?", :active => false, :children => { { :title => "Cheessus", :active => false }, { :title => "The impact of different cheeses / characteristics for cheese in relation to CHSE outcomes", :active => false } } } } } }

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  • Simplifying for-if messes with better structure?

    - by HH
    # Description: you are given a bitwise pattern and a string # you need to find the number of times the pattern matches in the string # any one liner or simple pythonic solution? import random def matchIt(yourString, yourPattern): """find the number of times yourPattern occurs in yourString""" count = 0 matchTimes = 0 # How can you simplify the for-if structures? for coin in yourString: #return to base if count == len(pattern): matchTimes = matchTimes + 1 count = 0 #special case to return to 2, there could be more this type of conditions #so this type of if-conditionals are screaming for a havoc if count == 2 and pattern[count] == 1: count = count - 1 #the work horse #it could be simpler by breaking the intial string of lenght 'l' #to blocks of pattern-length, the number of them is 'l - len(pattern)-1' if coin == pattern[count]: count=count+1 average = len(yourString)/matchTimes return [average, matchTimes] # Generates the list myString =[] for x in range(10000): myString= myString + [int(random.random()*2)] pattern = [1,0,0] result = matchIt(myString, pattern) print("The sample had "+str(result[1])+" matches and its size was "+str(len(myString))+".\n" + "So it took "+str(result[0])+" steps in average.\n" + "RESULT: "+str([a for a in "FAILURE" if result[0] != 8])) # Sample Output # # The sample had 1656 matches and its size was 10000. # So it took 6 steps in average. # RESULT: ['F', 'A', 'I', 'L', 'U', 'R', 'E']

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  • tabs using jquery

    - by sea_1987
    I currently have a tabbed system in place, however it not doing exactly as I need it too, I was hoping that by navigating to the URL with #tab2 suffixed on then end it would navigate to my tabbed page and the tab that is present in the URL would be the one that is active, however the first tab in the sequence is always active, is there a way to check what is being passed in the URL first and if there is #tabid present then make that tab the current tab? My javascript currently looks like this, $(".tab_content").hide(); //Hide all content $("ul.tabNavigation li.shortlist").addClass("active").show(); //Activate first tab (in this case second because of floats) $(".tab_content#shortlist").show(); //Show first tab content //On Click Event $("ul.tabNavigation li").click(function() { $("ul.tabNavigation li").removeClass("active"); //Remove any "active" class $(this).addClass("active"); //Add "active" class to selected tab $(".tab_content").hide(); //Hide all tab content var activeTab = $(this).find("a").attr("href"); //Find the href attribute value to identify the active tab + content $(activeTab).fadeIn(); //Fade in the active ID content return false; });

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  • Why does my JQuery Image swap not work in firefox or chrome, but fine in IE?

    - by Cognize
    Hi, Relatively new to JQuery. I've got some code that does a banner swap with a fade in fade out transition. The images swap as expected in IE8, chrome, and firefox. However, the actual fade, the smooth transition between images only works in IE. Can anyone point me in the right direction for a fix? Javascript: function swapImages() { var $active = $('#transitionImagePlaceHolder .active'); var $next = ($('#transitionImagePlaceHolder .active').next().length > 0) ? $('#transitionImagePlaceHolder .active').next() : $('#transitionImagePlaceHolder img:first'); $active.fadeOut( 'slow', function () { $next.fadeIn('slow').addClass('active'); $active.removeClass('active'); }); } $(document).ready(function () { setInterval('swapImages()', 5000); }); CSS: #transitionImagePlaceHolder { } #transitionImagePlaceHolder { position:relative; left: 26px; } #transitionImagePlaceHolder img { display:none; position:absolute; top:4; left:10; } HTML: <div id="transitionImagePlaceHolder"> <img class="active" src="Images/TransitionImages/Trans_Img_1.jpg" /> <img src="Images/TransitionImages/Trans_Img_2.jpg" /> <img src="Images/TransitionImages/Trans_Img_3.jpg" /> </div>

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  • incapsulation of a code inmatlab

    - by user531225
    my code is pathname=uigetdir; filename=uigetfile('*.txt','choose a file name.'); data=importdata(filename); element= (data.data(:,10)); in_array=element; pattern= [1 3]; locations = cell(1, numel(pattern)); for p = 1:(numel(pattern)) locations{p} = find(in_array == pattern(p)); end idx2 = []; for p = 1:numel(locations{1}) start_value = locations{1}(p); for q = 2:numel(locations) found = true; if (~any((start_value + q - 1) == locations{q})) found = false; break; end end if (found) idx2(end + 1) = locations{1}(p); end end [m2,n2]=size(idx2) res_name= {'one' 'two'}; res=[n n2]; In this code I finding a pattern in one of the column of my data file and counting how many times it's repeated. I have like 200 files that I want to do the same with them but unfotunatlly I'm stuck. this is what I have added so far pathname=uigetdir; files=dir('*.txt'); for k=1:length(files) filename=files(k).name; data(k)=importdata(files(k).name); element{k}=data(1,k).data(:,20); in_array=element;pattern= [1 3]; locations = cell(1, numel(pattern)); for p = 1:(numel(pattern)) locations{p} = find(in_array{k}== pattern(p)); end idx2{k} = []; how can I continue this code..??

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  • comparision of strings

    - by EmiLazE
    i am writing a program, that simulates game mastermind. but i am struggling on how to compare guessed pattern to key pattern. the game conditions are a little bit changed: patterns consist of letters. if an element of guessed pattern is equal to element of key pattern, and also index is equal, then print b. if an element of guessed pattern is equal to element of key pattern, but index is not, then print w. if an element of guessed pattern is not equal to element of key pattern, print dot. in feedback about guessed pattern, 'b's come first, 'w's second, '.'s last. my problem is that i cannot think of a way totally satisfies the answer. for (i=0; i<patternlength; i++) { for (x=0; x<patternlength; x++) { if (guess[i]==key[x] && i==x) printf("b"); if (guess[i]==key[x] && i!=x) printf("w"); if (guess[i]!=key[x]) printf("."); } }

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  • Visual Basic 2010: How to make window/form become active foreground?

    - by hervard
    I'm using Visual Basic 2010 Express. I have a form that can be minimized. There's also a tray icon. I've coded it so that if you double-click on the tray icon, the form's FormWindowState becomes set to Normal; this restores the form to where it to where it was before it became minimized, but the form does not become the active window on my desktop. How can I make the form become the active most foreground window? I've tried various functions that I can think of but no luck yet. Tried searching with various queries to try and find the right wording but no luck. I'm new to Visual Basic - only started a couple hours ago. Probably something simple but I can't seem to find the correct function or anything... Please enlighten me! Thanks.

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  • Any way to remove IEs black border around submit button in active forms?

    - by Magnar
    I am implementing a design that uses custom styled submit-buttons. They are quite simply light grey buttons with a slightly darker outer border: input.button { background: #eee; border: 1px solid #ccc; } This looks just right in Firefox, Safari and Opera. The problem is with Internet Explorer, both 6 and 7. Since the form is the first one on the page, it's counted as the main form - and thus active from the get go. The first submit button in the active form receives a solid black border in IE, to mark it as the main action. If I turn off borders, then the black extra border in IE goes away too. I am looking for a way to keep my normal borders, but remove the outline.

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  • What is a good pattern for binding a collection of objects coming from WCF, in Silverlight?

    - by Krishna
    Hi there, I've got a question about a Silverlight WCF Databinding pattern: There are many examples about how to bind data using {Binding} expressions in XAML, how to make async calls to a WCF service, set the DataContext property of a element in the UI, how to use ObservableCollections and INotifyPropertyChanged, INotifyCollectionChanged and so on. Background: I'm using the MVVM pattern, and have a Silverlight ItemsControl, whose ItemsSource is set to an ObservableCollection property on my ViewModel object. My view is of course the XAML which has the {Binding}. Say the model object is called 'Metric'. My ViewModel periodically makes calls to a WCF service that returns ObservableCollection. MetricInfo is the data transfer object (DTO). My question is two-fold: Is there any way to avoid copying each property of MetricInfo to the model class - Metric? When the WCF calls completes, is there any way to make sure I sync the items which are in both my local ObservableCollection and the result of the WCF call - without having to first clear out all the items in the local collection and then add all the ones from the WCF call result? thanks, Krishna

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  • Is it worthwhile to implement observer pattern in PHP?

    - by Extrakun
    I have been meaning to make use of design pattern in PHP, such as the observer pattern, but that I have to recreate the observers' relationship each time the page is loaded pains me. As references are saved as a new concrete objects in session, there is no way to preserve relationships between subscribers and their observers unless you use a GUID or some other properties to form a lookup, and store that property instead. With the cost of recreating the relationships each time a page is loaded, is it worthwhile to use design patterns such as observers in PHP, compared to having a clean design? Any real-world experience to share?

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  • what does "Net user administrator /active:yes" do to a computer?

    - by Rees
    i just purchased a new laptop and had some issues with it... I called tech support and they had me run this command in cmd prompt by right clicking the cmd icon and selecting "run as administrator" with root C:\windows\system32: "Net user administrator /active:no" after it was determined that it didn't fix the issue we ran this code "Net user administrator /active:yes" i then rebooted..and was asked for my windows login for my user account "Rees" as usual.. however ALL my settings where gone (including my desktop files) as though it was the first time I booted up. WHAT in the world happened with this command?? I desperately NEED my user accounts and files back to how they were!! (running windows 7) Please help!

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  • Unit tests only run automatically when active SDK is "simulator"?

    - by Steve Madsen
    I have followed the instructions Apple publishes for unit testing applications on iPhone and things work great when I set the active SDK to "iPhone Simulator". I have it configured to always build and run my tests as part of building the application itself. Apple implies (by omission) that this should work all of the time, but the tests are skipped when I set the active SDK to "iPhone Device". I am also linking with OCMock, and instead of a failing test, this warning is in the build log: ld: warning: in .../build/Debug-iphoneos/OCMock.framework/OCMock, missing required architecture arm in file It's very nice to make the unit test bundle a dependency of the main application, so these tests run at every build, but its utility is greatly diminished if it doesn't work during device builds. Is this a known, but undocumented, limitation?

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  • Is there a recommended way to use the Observer pattern in MVP using GWT?

    - by Tomislav Nakic-Alfirevic
    I am thinking about implementing a user interface according to the MVP pattern using GWT, but have doubts about how to proceed. These are (some of) my goals: - the presenter knows nothing about the UI technology (i.e. uses nothing from com.google.*) - the view knows nothing about the model or the presenter - the model knows nothing of the view or the presenter (...obviously) I would place an interface between the view and the presenter and use the Observer pattern to decouple the two: the view generates events and the presenter gets notified. What confuses me is that java.util.Observer and java.util.Observable are not supported in GWT. This suggests that what I'm doing is not the recommended way to do it, as far as GWT is concerned, which leads me to my questions: what is the recommended way to implement MVP using GWT, specifically with the above goals in mind? How would you do it?

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  • Is this a well known design pattern? what is it's name

    - by GenEric35
    Hi I have seen this often in code, but when I speak of it i don't know the name of such 'pattern' I have a method with 2 arguments that calls an overloaded method that has 3 arguments and intentionality sets the 3rd one to empty string. public DoWork(string name, string phoneNumber) { CreateContact(name, phoneNumber, string.Empty) } public DoWork(string name, string phoneNumber, string emailAddress) { //do the work } The reason I'm doing this is I to not duplicate code, and allow the existing callers to still call the method that has only 2 parameters. I have associate a few tags to this question, but it probably fit in more categories of questions. Is this a pattern, and does it have a name?

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  • Best Practices - Dynamic Reconfiguration

    - by jsavit
    This post is one of a series of "best practices" notes for Oracle VM Server for SPARC (formerly named Logical Domains) Overview of dynamic Reconfiguration Oracle VM Server for SPARC supports Dynamic Reconfiguration (DR), making it possible to add or remove resources to or from a domain (virtual machine) while it is running. This is extremely useful because resources can be shifted to or from virtual machines in response to load conditions without having to reboot or interrupt running applications. For example, if an application requires more CPU capacity, you can add CPUs to improve performance, and remove them when they are no longer needed. You can use even use Dynamic Resource Management (DRM) policies that automatically add and remove CPUs to domains based on load. How it works (in broad general terms) Dynamic Reconfiguration is done in coordination with Solaris, which recognises a hypervisor request to change its virtual machine configuration and responds appropriately. In essence, Solaris receives a message saying "you now have 16 more CPUs numbered 16 to 31" or "8GB more RAM starting at address X" or "here's a new network or disk device - have fun with it". These actions take very little time. Solaris then can start using the new resource. In the case of added CPUs, that means dispatching processes and potentially binding interrupts to the new CPUs. For memory, Solaris adds the new memory pages to its "free" list and starts using them. Comparable actions occur with network and disk devices: they are recognised by Solaris and then used. Removing is the reverse process: after receiving the DR message to free specific CPUs, Solaris unbinds interrupts assigned to the CPUs and stops dispatching process threads. That takes very little time. primary # ldm list NAME STATE FLAGS CONS VCPU MEMORY UTIL UPTIME primary active -n-cv- SP 16 4G 1.0% 6d 22h 29m ldom1 active -n---- 5000 16 8G 0.9% 6h 59m primary # ldm set-core 5 ldom1 primary # ldm list NAME STATE FLAGS CONS VCPU MEMORY UTIL UPTIME primary active -n-cv- SP 16 4G 0.2% 6d 22h 29m ldom1 active -n---- 5000 40 8G 0.1% 6h 59m primary # ldm set-core 2 ldom1 primary # ldm list NAME STATE FLAGS CONS VCPU MEMORY UTIL UPTIME primary active -n-cv- SP 16 4G 1.0% 6d 22h 29m ldom1 active -n---- 5000 16 8G 0.9% 6h 59m Memory pages are vacated by copying their contents to other memory locations and wiping them clean. Solaris may have to swap memory contents to disk if the remaining RAM isn't enough to hold all the contents. For this reason, deallocating memory can take longer on a loaded system. Even on a lightly loaded system it took several 7 or 8 seconds to switch the domain below between 8GB and 24GB of RAM. primary # ldm set-mem 24g ldom1 primary # ldm list NAME STATE FLAGS CONS VCPU MEMORY UTIL UPTIME primary active -n-cv- SP 16 4G 0.1% 6d 22h 36m ldom1 active -n---- 5000 16 24G 0.2% 7h 6m primary # ldm set-mem 8g ldom1 primary # ldm list NAME STATE FLAGS CONS VCPU MEMORY UTIL UPTIME primary active -n-cv- SP 16 4G 0.7% 6d 22h 37m ldom1 active -n---- 5000 16 8G 0.3% 7h 7m What if the device is in use? (this is the anecdote that inspired this blog post) If CPU or memory is being removed, releasing it pretty straightforward, using the method described above. The resources are released, and Solaris continues with less capacity. It's not as simple with a network or I/O device: you don't want to yank a device out from underneath an application that might be using it. In the following example, I've added a virtual network device to ldom1 and want to take it away, even though it's been plumbed. primary # ldm rm-vnet vnet19 ldom1 Guest LDom returned the following reason for failing the operation: Resource Information ---------------------------------------------------------- ----------------------- /devices/virtual-devices@100/channel-devices@200/network@1 Network interface net1 VIO operation failed because device is being used in LDom ldom1 Failed to remove VNET instance That's what I call a helpful error message - telling me exactly what was wrong. In this case the problem is easily solved. I know this NIC is seen in the guest as net1 so: ldom1 # ifconfig net1 down unplumb Now I can dispose of it, and even the virtual switch I had created for it: primary # ldm rm-vnet vnet19 ldom1 primary # ldm rm-vsw primary-vsw9 If I had to take away the device disruptively, I could have used ldm rm-vnet -f but that could disrupt whoever was using it. It's better if that can be avoided. Summary Oracle VM Server for SPARC provides dynamic reconfiguration, which lets you modify a guest domain's CPU, memory and I/O configuration on the fly without reboot. You can add and remove resources as needed, and even automate this for CPUs by setting up resource policies. Taking things away can be more complicated than giving, especially for devices like disks and networks that may contain application and system state or be involved in a transaction. LDoms and Solaris cooperative work together to coordinate resource allocation and de-allocation in a safe and effective way. For best practices, use dynamic reconfiguration to make the best use of your system's resources.

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  • How to force Weblogic to start deployments in active state (i.e. not just prepared)

    - by doublep
    When I start a Weblogic instance with a deployed application, the deployment is sometimes left in prepared state, not in active state. I have to go to Weblogic Console and start the deployment manually, which is quite slow and annoying repetetive work. Since this is done on a development machine — sometimes 50 times a day, — there are no security implication as the server is only visible on the local network. Is there some way to have it always start the deployment active? Note that I'm not redeploying the application, I instead have it "constantly deployed" and stop/start the Weblogic instance using the scripts in bin directory.

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  • Stream classes ... design, pattern for creating views over streams

    - by ToxicAvenger
    A question regarding the design of stream classes - I need a pattern to create independent views over a single stream instance (in my case for reading). A view would be a consecutive part of the stream. The problem I have with the stream classes is that the state (reading or writing) is coupled with the underlying data/storage. So if I need to partition a stream into different segments (whether segments overlap or not doesn't matter), I cannot easily create views over the stream, the views would store start and end position. Because reading from a view - which would translate to reading from the underlying stream adjusted based on the start/end positions - would change the state of the underlying stream instance. So what I could do is take a read on a view instance, adjust the Position of the stream, read the chunks I need. But I cannot do that concurrently. Why is it designed in such a way, and what kind of pattern could I implement to create independet views over a single stream instance which would allow to read/write independently (and concurrently)?

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  • Cloud to On-Premise Connectivity Patterns

    - by Rajesh Raheja
    Do you have a requirement to convert an Opportunity in Salesforce.com to an Order/Quote in Oracle E-Business Suite? Or maybe you want the creation of an Oracle RightNow Incident to trigger an on-premise Oracle E-Business Suite Service Request creation for RMA and Field Scheduling? If so, read on. In a previous blog post, I discussed integrating TO cloud applications, however the use cases above are the reverse i.e. receiving data FROM cloud applications (SaaS) TO on-premise applications/databases that sit behind a firewall. Oracle SOA Suite is assumed to be on-premise with with Oracle Service Bus as the mediation and virtualization layer. The main considerations for the patterns are are security i.e. shielding enterprise resources; and scalability i.e. minimizing firewall latency. Let me use an analogy to help visualize the patterns: the on-premise system is your home - with your most valuable possessions - and the SaaS app is your favorite on-line store which regularly ships (inbound calls) various types of parcels/items (message types/service operations). You need the items at home (on-premise) but want to safe guard against misguided elements of society (internet threats) who may masquerade as postal workers and vandalize property (denial of service?). Let's look at the patterns. Pattern: Pull from Cloud The on-premise system polls from the SaaS apps and picks up the message instead of having it delivered. This may be done using Oracle RightNow Object Query Language or SOAP APIs. This is particularly suited for certain integration approaches wherein messages are trickling in, can be centralized and batched e.g. retrieving event notifications on an hourly schedule from the Oracle Messaging Service. To compare this pattern with the home analogy, you are avoiding any deliveries to your home and instead go to the post office/UPS/Fedex store to pick up your parcel. Every time. Pros: On-premise assets not exposed to the Internet, firewall issues avoided by only initiating outbound connections Cons: Polling mechanisms may affect performance, may not satisfy near real-time requirements Pattern: Open Firewall Ports The on-premise system exposes the web services that needs to be invoked by the cloud application. This requires opening up firewall ports, routing calls to the appropriate internal services behind the firewall. Fusion Applications uses this pattern, and auto-provisions the services on the various virtual hosts to secure the topology. This works well for service integration, but may not suffice for large volume data integration. Using the home analogy, you have now decided to receive parcels instead of going to the post office every time. A door mail slot cut out allows the postman can drop small parcels, but there is still concern about cutting new holes for larger packages. Pros: optimal pattern for near real-time needs, simpler administration once the service is provisioned Cons: Needs firewall ports to be opened up for new services, may not suffice for batch integration requiring direct database access Pattern: Virtual Private Networking The on-premise network is "extended" to the cloud (or an intermediary on-demand / managed service offering) using Virtual Private Networking (VPN) so that messages are delivered to the on-premise system in a trusted channel. Using the home analogy, you entrust a set of keys with a neighbor or property manager who receives the packages, and then drops it inside your home. Pros: Individual firewall ports don't need to be opened, more suited for high scalability needs, can support large volume data integration, easier management of one connection vs a multitude of open ports Cons: VPN setup, specific hardware support, requires cloud provider to support virtual private computing Pattern: Reverse Proxy / API Gateway The on-premise system uses a reverse proxy "API gateway" software on the DMZ to receive messages. The reverse proxy can be implemented using various mechanisms e.g. Oracle API Gateway provides firewall and proxy services along with comprehensive security, auditing, throttling benefits. If a firewall already exists, then Oracle Service Bus or Oracle HTTP Server virtual hosts can provide reverse proxy implementations on the DMZ. Custom built implementations are also possible if specific functionality (such as message store-n-forward) is needed. In the home analogy, this pattern sits in between cutting mail slots and handing over keys. Instead, you install (and maintain) a mailbox in your home premises outside your door. The post office delivers the parcels in your mailbox, from where you can securely retrieve it. Pros: Very secure, very flexible Cons: Introduces a new software component, needs DMZ deployment and management Pattern: On-Premise Agent (Tunneling) A light weight "agent" software sits behind the firewall and initiates the communication with the cloud, thereby avoiding firewall issues. It then maintains a bi-directional connection either with pull or push based approaches using (or abusing, depending on your viewpoint) the HTTP protocol. Programming protocols such as Comet, WebSockets, HTTP CONNECT, HTTP SSH Tunneling etc. are possible implementation options. In the home analogy, a resident receives the parcel from the postal worker by opening the door, however you still take precautions with chain locks and package inspections. Pros: Light weight software, IT doesn't need to setup anything Cons: May bypass critical firewall checks e.g. virus scans, separate software download, proliferation of non-IT managed software Conclusion The patterns above are some of the most commonly encountered ones for cloud to on-premise integration. Selecting the right pattern for your project involves looking at your scalability needs, security restrictions, sync vs asynchronous implementation, near real-time vs batch expectations, cloud provider capabilities, budget, and more. In some cases, the basic "Pull from Cloud" may be acceptable, whereas in others, an extensive VPN topology may be well justified. For more details on the Oracle cloud integration strategy, download this white paper.

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  • Cloud to On-Premise Connectivity Patterns

    - by Rajesh Raheja
    Do you have a requirement to convert an Opportunity in Salesforce.com to an Order/Quote in Oracle E-Business Suite? Or maybe you want the creation of an Oracle RightNow Incident to trigger an on-premise Oracle E-Business Suite Service Request creation for RMA and Field Scheduling? If so, read on. In a previous blog post, I discussed integrating TO cloud applications, however the use cases above are the reverse i.e. receiving data FROM cloud applications (SaaS) TO on-premise applications/databases that sit behind a firewall. Oracle SOA Suite is assumed to be on-premise with with Oracle Service Bus as the mediation and virtualization layer. The main considerations for the patterns are are security i.e. shielding enterprise resources; and scalability i.e. minimizing firewall latency. Let me use an analogy to help visualize the patterns: the on-premise system is your home - with your most valuable possessions - and the SaaS app is your favorite on-line store which regularly ships (inbound calls) various types of parcels/items (message types/service operations). You need the items at home (on-premise) but want to safe guard against misguided elements of society (internet threats) who may masquerade as postal workers and vandalize property (denial of service?). Let's look at the patterns. Pattern: Pull from Cloud The on-premise system polls from the SaaS apps and picks up the message instead of having it delivered. This may be done using Oracle RightNow Object Query Language or SOAP APIs. This is particularly suited for certain integration approaches wherein messages are trickling in, can be centralized and batched e.g. retrieving event notifications on an hourly schedule from the Oracle Messaging Service. To compare this pattern with the home analogy, you are avoiding any deliveries to your home and instead go to the post office/UPS/Fedex store to pick up your parcel. Every time. Pros: On-premise assets not exposed to the Internet, firewall issues avoided by only initiating outbound connections Cons: Polling mechanisms may affect performance, may not satisfy near real-time requirements Pattern: Open Firewall Ports The on-premise system exposes the web services that needs to be invoked by the cloud application. This requires opening up firewall ports, routing calls to the appropriate internal services behind the firewall. Fusion Applications uses this pattern, and auto-provisions the services on the various virtual hosts to secure the topology. This works well for service integration, but may not suffice for large volume data integration. Using the home analogy, you have now decided to receive parcels instead of going to the post office every time. A door mail slot cut out allows the postman can drop small parcels, but there is still concern about cutting new holes for larger packages. Pros: optimal pattern for near real-time needs, simpler administration once the service is provisioned Cons: Needs firewall ports to be opened up for new services, may not suffice for batch integration requiring direct database access Pattern: Virtual Private Networking The on-premise network is "extended" to the cloud (or an intermediary on-demand / managed service offering) using Virtual Private Networking (VPN) so that messages are delivered to the on-premise system in a trusted channel. Using the home analogy, you entrust a set of keys with a neighbor or property manager who receives the packages, and then drops it inside your home. Pros: Individual firewall ports don't need to be opened, more suited for high scalability needs, can support large volume data integration, easier management of one connection vs a multitude of open ports Cons: VPN setup, specific hardware support, requires cloud provider to support virtual private computing Pattern: Reverse Proxy / API Gateway The on-premise system uses a reverse proxy "API gateway" software on the DMZ to receive messages. The reverse proxy can be implemented using various mechanisms e.g. Oracle API Gateway provides firewall and proxy services along with comprehensive security, auditing, throttling benefits. If a firewall already exists, then Oracle Service Bus or Oracle HTTP Server virtual hosts can provide reverse proxy implementations on the DMZ. Custom built implementations are also possible if specific functionality (such as message store-n-forward) is needed. In the home analogy, this pattern sits in between cutting mail slots and handing over keys. Instead, you install (and maintain) a mailbox in your home premises outside your door. The post office delivers the parcels in your mailbox, from where you can securely retrieve it. Pros: Very secure, very flexible Cons: Introduces a new software component, needs DMZ deployment and management Pattern: On-Premise Agent (Tunneling) A light weight "agent" software sits behind the firewall and initiates the communication with the cloud, thereby avoiding firewall issues. It then maintains a bi-directional connection either with pull or push based approaches using (or abusing, depending on your viewpoint) the HTTP protocol. Programming protocols such as Comet, WebSockets, HTTP CONNECT, HTTP SSH Tunneling etc. are possible implementation options. In the home analogy, a resident receives the parcel from the postal worker by opening the door, however you still take precautions with chain locks and package inspections. Pros: Light weight software, IT doesn't need to setup anything Cons: May bypass critical firewall checks e.g. virus scans, separate software download, proliferation of non-IT managed software Conclusion The patterns above are some of the most commonly encountered ones for cloud to on-premise integration. Selecting the right pattern for your project involves looking at your scalability needs, security restrictions, sync vs asynchronous implementation, near real-time vs batch expectations, cloud provider capabilities, budget, and more. In some cases, the basic "Pull from Cloud" may be acceptable, whereas in others, an extensive VPN topology may be well justified. For more details on the Oracle cloud integration strategy, download this white paper.

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