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  • SQL Server Database Settings

    - by rbishop
    For those using Data Relationship Management on Oracle DB this does not apply, but for those using Microsoft SQL Server it is highly recommended that you run with Snapshot Isolation Mode. The Data Governance module will not function correctly without this mode enabled. All new Data Relationship Management repositories are created with this mode enabled by default. This mode makes SQL Server (2005+) behave more like Oracle DB where readers simply see older versions of rows while a write is in progress, instead of readers being blocked by locks while a write takes place. Many common sources of deadlocks are eliminated. For example, if one user starts a 5 minute transaction updating half the rows in a table, without snapshot isolation everyone else reading the table will be blocked waiting. With snapshot isolation, they will see the rows as they were before the write transaction started. Conversely, if the readers had started first, the writer won't be stuck waiting for them to finish reading... the writes can begin immediately without affecting the current transactions. To make this change, make sure no one is using the target database (eg: put it into single-user mode), then run these commands: ALTER DATABASE [DB] SET ALLOW_SNAPSHOT_ISOLATION ONALTER DATABASE [DB] SET READ_COMMITTED_SNAPSHOT ON Please make sure you coordinate with your DBA team to ensure tempdb is appropriately setup to support snapshot isolation mode, as the extra row versions are stored in tempdb until the transactions are committed. Let me take this opportunity to extremely strongly highly recommend that you use solid state storage for your databases with appropriate iSCSI, FiberChannel, or SAN bandwidth. The performance gains are significant and there is no excuse for not using 100% solid state storage in 2013. Actually unless you need to store petabytes of archival data, there is no excuse for using hard drives in any systems, whether laptops, desktops, application servers, or database servers. The productivity benefits alone are tremendous, not to mention power consumption, heat, etc.

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  • SEO and external sites that serve responsive images (like Re-SRC)

    - by Baumr
    Re-SRC is a tool that allows you to automatically serve responsive images for your website from their cloud servers. It delivers a new image file each time the browser window (viewport) is resized. To use it in your HTML when linking to an image, you would do the following: <img src="http://app.resrc.it//www.your-domain.com/img/img001.jpg"/> Some more background for SEO considerations: As an example, looking at their demo page's code, the src of the Arc de Triomphe photo — when the browser window is resized to be at a tablet-width — shows this particular file at it's widest. It is found under the following URL: http://app4-uk.resrc.it/s=w560,pd1/ro=h//www.resrc.it/img/demo/demo-image-1.jpg If the viewport is increased to desktop-width, then a smaller image is served in line with the design; see this URL: http://app4-uk.resrc.it/s=w320,pd1/ro=h//www.resrc.it/img/demo/demo-image-1.jpg If I change the viewport to be about half-way between those two, then the image's URL is: http://app4-uk.resrc.it/s=w240,pd1/ro=h//www.resrc.it/img/demo/demo-image-1.jpg In other words, I found that there is a separate file for every 10-pixel increment of the image width. Very cool for saving bandwidth on mobile devices and service responsive/retina images on others, but... Here are two problems I see for SEO: The img on your site, part of your semantic markup, will not be hosted on your site at all, or even a server you control. Any links to these images will pass on "link juice" to Re-SRC's site instead. You are serving a vast array of different image files to different people — some may link to one, others to another size. Then there's the question of what different search engine crawlers will see. Also: There seems to be no fallback option if their servers are down. Do you see any other concerns? Or, perhaps, do you not see those as concerns?

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  • eSTEP Newsletter November 2011 now available

    - by uwes
    Dear Partners,We would like to inform you that the November issue of our Newsletter is now available.The issue contains informations to the following topics:Notes from Corporate: Magic Quadrant for Enterprise Application Servers, Oracle Buys RightNow Technical Corner: Oracle Solaris 11 – The First Cloud OS, Oracle Solaris 10 8/11 now available, New RAC/Containers certifications, DTrace and Container for Oracle Linux, Oracle Enterprise Manager Ops Center released, News from the Oracle Solaris Cluster, SPARC - New roadmap, T-Series Benchmarks Learning & Events: eSTEP Events Schedule, Recently Delivered TechCasts, Delivered Campaigns in 2011 How to ...: About Oracle Solaris Containers, Detailed feature comparison between the different versions of database 11g, Upgrade Advantage Program + table with examples, Sun Software Name ===> New Oracle Name, Oracle Linux and OVM Certification Search, TO YOUR ATTENTION - Repricing Servers and Xoptions You find the Newsletter on our portal under eSTEP News ---> Latest Newsletter. You will need to provide your email address and the pin below to get access. Link to the portal is shown below.URL: http://launch.oracle.com/PIN: eSTEP_2011Previous published Newsletters can be found under the Archived Newsletters section and more useful information under the Events, Download and Links tab. Feel free to explore and any feedback is appreciated to help us improve the service and information we deliver.Thanks and best regards,Partner HW Enablement EMEA

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  • How to start WebLogic Server using default scripts?

    - by Luz Mestre-Oracle
    There are a few common issues reported when starting weblogic server using scripts. 1. User is not able to access weblogic console. 2. After a few days/hours weblogic server stops abruptly. 3. When user closes putty, they are not able to connect to weblogic server anymore. 4. When user closes windows command prompt, they are not able to connect to weblogic server anymore. 5. Weblogic is started using startManagedWebLogic.cmd/startManagedWebLogic.sh. By default, WebLogic Server does not run in background mode, so after you close the window the process finishes as well. In Linux/Unix based platforms, you need to use: nohup ./startManagedWebLogic.sh <Server> <URL> & In Windows platforms, you need to start Managed Servers using Windows Services: How to Install MS Windows Services For FMW 11g WebLogic Domain Admin and Managed Servers (Doc ID 1060058.1) http://docs.oracle.com/cd/E23943_01/web.1111/e13708/winservice.htm There a few more reasons that could cause similar symptoms, like JVM crash, signals sent by the Operating System, and many other reasons.  But the above steps is the first one to start. Enjoy!

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  • TCO Models: Oracle invites you to the next webcast dedicated to Partners on Oracle Hardware and Solutions

    - by mseika
    The Oracle Hardware and Solutions Webcast Series is a sequence of one-hour Sales-Oriented Web Seminars, dedicated to Oracle Partners. This is your opportunity to learn about Oracle's Servers, Storage and Solutions strategy and portfolio, and their business value for you and your customers. The next appointment is for Wednesday, June 22, at 9am UKT / 10am CET:Total Cost of Ownership Models Examples: How we can sell Oracle HW and SW together, with better TCO, and benefits for both Oracle and the Partner!with Ilkka Vanhanen, Business Development Manager, Oracle EMEA Hardware Strategy Organization, who will talk about:   Concrete examples of the HW/SW TCO Model   Understand the competitive advantage provided by Oracle-on-Oracle Solutions   How Partners get new business from Oracle-on-Oracle Solutions   How Oracle is changing the game in Enterprise IT   Key benefits for both SW Resellers and HW Resellers   To register click here , then click on the “Servers and Solutions Webcasts” tab.          

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  • accessing files on a shared folder via IIS

    - by Darkcat Studios
    Im not sure if this suits stackexchange, serverfault or here... so i'll go with here for a start. I'm having issues setting up a network share to be accessed by IIS, all I need to do is read/write files on the Other server. We have 2 servers set up (Both 2008 R2 & IIS 7.5), one is the WEB server, which is externally accessible and NOT part of the domain. We also have an Intranet server which has no internet connectivity and is part of the domain. These 2 servers can talk to each other happily, I have the SQL server on the WEB server shared across to the intranet server so that the web content is editable from the intranet. I can share a folder on the web server (say, wwwroot/Images/) and connect to it from the intranet server, even have it as a mapped drive (but i know thats not going to work for IIS to access it), So there seems not to be a connectivity issue. I can also set up a Virtual folder in IIS on the Intranet server - this is where it gets annoying - I cant connect using pass-through authentication because there is no suitable user on the web server (which is not on the domain). If i set up a user on the web server, eg Intranet_USR, and give it appropriate rights to the folder, files and share, i can connect, but only view folder contents in IIS, not read, although that user has read privileges!! Any help much appreciated!

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  • Ubuntu Server 12.04 as a router. Problem with DNS?? Or Routing table?

    - by Lorenzo
    I have a virtualbox lab made up of 4 Windows 2008 R2 servers (DC/DNS,SQL,SHAREPOINT, EXCHANGE) that are configured with static ip addresses with NIC's attached to Internal network. Everything works. I had the requirement to execute some tests that also access external services available on the internet. To keep things clean and similar to the production environment I have installed another VM, with Ubuntu Server 12.04 64 bit and configured (I hope) to work as a router like described on this post. This VM has two network interfaces: first is Bridged with the host and is used as a WAN connection and the other one attached in the Internal Network with its own static IP address on the internal network subnet. But actually the Windows servers does not connect to the internet while the unix one connects. I did a route command. this is the result: Kernel IP Routing table Destination Gateway Genmask Flags Metric Ref Use Iface default 10.69.121.1 0.0.0.0 UG 100 0 0 eth0 10.69.121.0 * 255.255.255.0 U 0 0 0 eth0 192.168.83.0 * 255.255.255.0 U 0 0 0 eth1 Can somebody help me with this configuration? :) Thanks! Addendum: I forgot to mention that one of the windows server hosts a DNS service for which I should maybe configure a forwarding server but I do not exactly know which server to forward on... :(

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  • WIFI looses connection with AR9285 - have to disconnect / connect to regain internet?

    - by CodyLoco
    I have a G73JW laptop using Ubuntu 12.04. It has an Atheros AR9285 card. While wifi seems to work fine most of the time, about every hour or two it will loose the connection to the internet. The connection will appear to be connected still to the wireless router, but internet access is gone. Disconnecting and reconnecting to the access point solves the problem, as does disabling and reenabling the adapter via the hardware keyboard shortcut. How might this be solved so the connection is stable and doesn't drop? EDIT: It looks like the network dropping isn't related to DNS as it fails either way: codyloco@CodyLoco-Ubuntu:~$ dig askubuntu.com @8.8.8.8 ; <<>> DiG 9.8.1-P1 <<>> askubuntu.com @8.8.8.8 ;; global options: +cmd ;; connection timed out; no servers could be reached codyloco@CodyLoco-Ubuntu:~$ dig askubuntu.com ; <<>> DiG 9.8.1-P1 <<>> askubuntu.com ;; global options: +cmd ;; connection timed out; no servers could be reached Again cycling (disabling / enabling) the adapter corrects the issue.

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  • is Java free for mobile development?

    - by exTrace101
    Q1. I would like to know if it's free for a developer (I mean, if I have to pay no royalties to Sun/Oracle) to develop (Android) mobile apps in Java? After reading this snippet about use of Java field, I'm getting the impression that Java is not free for mobile development, is that right? .."General Purpose Desktop Computers and Servers" means computers, including desktop and laptop computers, or servers, used for general computing functions under end user control (such as but not specifically limited to email, general purpose Internet browsing, and office suite productivity tools). The use of Software in systems and solutions that provide dedicated functionality (other than as mentioned above) or designed for use in embedded or function-specific software applications, for example but not limited to: Software embedded in or bundled with industrial control systems, wireless mobile telephones, wireless handheld devices, netbooks, kiosks, TV/STB, Blu-ray Disc devices, telematics and network control switching equipment, printers and storage management systems, and other related systems are excluded from this definition and not licensed under this Agreement... and from http://www.excelsiorjet.com/embedded/ Notice : The Java SE Embedded technology license currently prohibits the use of Java SE in cell phones. Q2. how come these plethora of Android Java developers aren't paying Sun/Oracle a dime?

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  • Where can I learn about managing domain names for my websites? [closed]

    - by Shahbaz
    [I originally asked this question on serverfault.com, where it was closed as 'out of scope.' Hopefully it is appropriate for this forum] I am a developer who doesn't understand how to effectively manage Internet domain names. Say I registered a name with namecheap and host a website on linode. Now what is an a-record? What is a name server and do I host it with namecheap of linode? Why would I pay amazon when others are free? Does any of this matter in terms of website latency or reliability? I feel like a script kiddy, copying and pasting others' and hoping it works. Is there a book or other resource that explains all this? I know amazon is full of books about DNS, but afaik they are about setting up DNA servers for local networks, not the Internet. p.s. To emphasize, I'm asking for books or long write-ups which explain this to technically competent people, who just haven't had to think about the role of commercial registrars, name servers, commercial hosts, commercial websites and how all parts play together on the real internet (not local networks).

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  • How to enable a Web portal-based rich enterprise platform on different domains and hosts using JS without customization/ server configuration

    - by S.Jalali
    Our company Coscend has built a Web portal-based communications and cloud collaboration platform by using JavaScript (JS), which is embedded in HTML5 and formatted with CSS3. Other technologies used in the core code include Flash, Flex, PostgreSQL and MySQL. Our team would like to host this platform on five different Windows and Linux environments that run different types of Web servers such as IIS and Apache. Technical challenge: Each of these Windows and Linux servers have a different host name and domain name (and IP address), but we would like to keep our enterprise platform independent of host server configuration. Possible approach to solution: We think an API (interface module with a GUI) is needed to accomplish this level of modularity and flexibility while deploying at our enterprise customers. Seeking your insights: In this context, our team would appreciate your guidance on: Is there an algorithmic method to implement this Web portal-based platform in these Windows and Linux environments while separating it from server configuration, i.e., customizing the host name, domain name and IP address for each individual instance? For example, would it be suitable to create some JS variables / objects for host name and domain name and call them in the different implementations? If a reference to the host/domain names occurs on hundreds of portal modules, these variables or JS objects would replace that. If so, what is the best way to make these object modules written in JS portable and re-usable across different environments and instances for enterprise customers? Here is an example of the implemented code for the said platform. The following Web site (www.CoscendCommunications.com) was built using this enterprise collaboration platform and has the base code examples of the platform. This Web site is domain-specific. We like to make the underlying platform such that it is domain and host-independent. This will allow the underlying platform to be deployed in multiple instances of our enterprise customers.

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  • Dynamic Monitoring Service (DMS) Configuration Dumping and CPU Utilization

    - by ShawnBailey
    There was recently a report of CPU spikes on a system that were occuring at precise 3 hour intervals. Research revealed that the spikes were the result of the Dynamic Monitoring Service generating a metrics dump and writing it under the server 'logs' folder for every WLS server in the domain. This blog provides some information on what this is for and how to control it. The Dynamic Monitoring Service is a facility in FMw (JRF to be more precise) that collects runtime data on the components deployed to WebLogic. Each component is responsible for how much or how little they use the service and SOA collects a fair amount of information. To view what is collected on any running server you can use the following URL, http://host:port/dms/Spy and login with admin credentials. DMS is essentially always running and collecting this information in the runtime and to protect against loss of this data it also runs automatic backups, by default at the 3 hour interval mentioned above. Most of the management options for DMS are exposed through WLST but these settings are not so we must open the dms_config.xml file which can be found in DOMAIN_HOME/config/fmwconfig/servers/<server_name>/dms_config.xml. The contents are fairly short and at the bottom you will find the following entry: <dumpConfiguration>     <dump intervalSeconds="10800" maxSizeMBytes="75" enabled="true"/> </dumpConfiguration> The interval of 10800 seconds corresponds to the 3 hours and the maximum size is 75MB. The file is written as an archive to DOMAIN_HOME/servers/<server_name>/logs/metrics. This archive contains the dump in XML format. You can disable the dumps all together by simply setting the 'enabled' value to 'false' or of course you could modify the other parameters to suit your needs. Disabling the dumps will NOT impact DMS collections or display at runtime. It will only eliminate these periodic backups.

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  • Solutions for "Maintenance Mode"

    - by Ka Lyse
    Given a web application running across 10+ servers, what techniques have you put in place for doing things like altering the state of your website so that you can implement certain features. For instance, you might want to: Restrict Logins/Disable Certain Features Turn Site to "Read Only" Turn Site to Single "Maintenance Mode" page. Doing any of the above is pretty trivial. You can throw a particular "flag" in an .ini file, or add a row/value to a site_options table in your database and just read that value and do the appropriate thing. But these solutions have their problems. Disadvantages/Problems For instance, if you use a file for your application, and you want to switch off a certain feature temporarily, then you need to update this file on all servers. So then you might want to look at running something like ZooKeeper, but you are probably overcomplicating things. So then, you might decide that you want to store these "feature" flags in a database. But then you are obviously adding unncessary queries to each page request. So you think to yourself, that you will throw memcached in to the mix and just cache the query. Then you just retrieve all of your "Features" from memcached and add a 2ms~ latency to your application on every page. So to get around this, you decide to use a two tier-cache system, whereby you use an inmemory cache on each machine, (like Apc/Redis etc). This would work, but then it gets complicated, because you would have to set the key/hash life to perhaps 60 seconds, so that when you purge/invalidate the memcached object storing your "Features" result, your on machine cache is prompt enough to get the the new states. What suggestions might you have? Keeping in mind that optimization/efficiency is the priority here.

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  • Google Rolls Out Secured Search. It’s Slightly Different From Regular Search

    - by Gopinath
    Google rolled out secured version of it’s search engine at https://google.com (did you notice https instead of http?). This search engine lets everyone to use Google search in a secured way. How is it secured? When you use https://google.com, the data exchanged between your browser and Google servers is encrypted to make sure that no one can sniff it. Is my search history secured from Google? No. The search queries you submit to Google are stored in Google servers. There is no change Google’s search history recording. Any differences between Regular Search and Secured Search Results? Yes. Secured search is slightly different from regular search. When you are accessing Google Secured Search Image search options will not be available on the left side bar. Site may respond slow compared to regular search site as there is a overhead to establish between your browser and the server. Join us on Facebook to read all our stories right inside your Facebook news feed.

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  • Solaris 11 VNC Server is "blurry" or "smeared"

    - by user12620111
    I've been annoyed by quality of the image that is displayed by my VNC viewer when I visit a Solaris 11 VNC server. How should I describe the image? Blurry? Grainy? Smeared? Low resolution? Compressed? Badly encoded? This is what I have gotten used to seeing on Solaris 11: This is not a problem for me when I view Solaris 10 VNC servers. I've finally taken the time to investigate, and the solution is simple. On the VNC client, don't allow "Tight" encoding. My VNC Viewer will negotiate to Tight encoding if it is available. When negotiating with the Solaris 10 VNC server, Tight is not a supported option, so the Solaris 10 server and my client will agree on ZRLE.  Now that I have disabled Tight encoding on my VNC client, the Solaris 11 VNC Servers looks much better: How should I describe the display when my VNC client is forced to negotiate to ZRLE encoding with the Solaris 11 VNC Server? Crisp? Clear? Higher resolution? Using a lossless compression algorithm? When I'm on a low bandwidth connection, I may re-enable Tight compression on my laptop. In the mean time, the ZRLE compression is sufficient for a coast-to-coast desktop, through the corporate firewall, encoded with VPN, through my ISP and onto my laptop. YMMV.

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  • How similiar should the environments of PreProd and Prod be?

    - by RoboShop
    I've just recently been on a project and during the release, we realized that it didn't work in Production. It works in all other environments but because we have a separate release team, and we cannot set up the servers and environments ourselves, we have no visibility of the configuration on them. We suspect that Prod has some user permissions in its account or IIS settings that are different, so we are working though it now. So I think this whole thing has been a learning experience for me and I don't want the same thing repeated again. I would like to ask, how different should these environments be? I always thought that PreProd should be an identical copy to the Prod environment using a copy of the same database, using a copy of the same user account, should be installed on the same servers etc. But how far should I take it? If the web site is externally facing, should PreProd be externally facing? What if the website has components that don't require a user account or password to navigate to? Is it still okay to expose it to the outside world?

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  • Network/browser issues after upgrade to 12.04

    - by Reg
    I let my laptop upgrade to 12.04. And have no network afterwards. I went through all the articles I could find in google. Right now, I can ping google, and yahoo, but not cnn.com for example or anything else. Firefox says it can't reach google.com or gmail.com (or anything, not even IP. /etc/network/interfaces dns-nameservers 8.8.8.8 <<<<<added auto lo iface lo inet loopback /etc/dhcp/dhclient.conf #prepend domain-name-servers 8.8.8.8,8.8.4.4; prepend domain-name-servers 127.0.0.1; <<<<< tried both /etc/NetworkManager/NetworkManager.conf with and without dns=dnsmasq commented out. I can ping my wireless router and connect to it just fine. Have tried proxy/noproxy. This looks like After Upgrade to 12.04 - cannot connect to network but no answer there. I would hate to do a fresh install. Any assistance appreciated.

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  • ?12c????RAC Cluster Hub Node-Leaf Node

    - by Liu Maclean(???)
    ?12c?cluster?????????????,?????????????flex cluster?flux asm?? ??Hub Node?Leaf Node,?????Hub Node?Leaf Node. Hub Node????: A node in and Oracle Flex Cluster that is tightly connected with other servers and has direct access to a shared disk. Leaf Node????: Servers that are loosely coupled with Hub Nodes, which may not have direct access to the shared storage. ?????????? Leaf Node??????shared storage ,????leaf node??share disk?? ??Hub Node?12c?????cluster node???, ?Leaf Node????? Leaf Node???: ? Hub Node?? ?????cluster?? ????????Hub Node ????Hub Node????? Hub Node????????????Leaf Node??? ??????????? ?Hub Node????? ??Leaf Node??Flex Cluster???????: hub-and-spoke???cluster?????????? ????Hub Node????OCR?Votedisk ????HUB node???,???????clusterware?????,??ocr?Votedisk ? ?????????????? ??????????,???????? ????????,12???Flex cluster??12?????, ???????? [ n * (n-1)]/2?66?????? ???1000?????,?????????????40?Hub Node,???Hub Node??24?Leaf Node,?Flex Cluster???1740??????  ????,??Cluster??499500?????? ?Flex Cluster??????????????,??cluster software????? ??Hub Node ?? ????????? , ??????????relocate???Hub Node ?Hub Node???Leaf Node??????,????????relocate???Leaf Node? ??Leaf Node?? ?????????,????????relocate????Leaf Node?

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  • SQL Server 2005 Blocking Problem (ASYNC_NETWORK_IO)

    - by ivankolo
    I am responsible for a third-party application (no access to source) running on IIS and SQL Server 2005 (500 concurrent users, 1TB data, 8 IIS servers). We have recently started to see significant blocking on the database (after months of running this application in production with no problems). This occurs at random intervals during the day, approximately every 30 minutes, and affects between 20 and 100 sessions each time. All of the sessions eventually hit the application time out and the sessions abort. The problem disappears and then gradually re-emerges. The SPID responsible for the blocking always has the following features: WAIT TYPE = ASYNC_NETWORK_IO The SQL being run is “(@claimid varchar(15))SELECT claimid, enrollid, status, orgclaimid, resubclaimid, primaryclaimid FROM claim WHERE primaryclaimid = @claimid AND primaryclaimid < claimid)”. This is relatively innocuous SQL that should only return one or two records, not a large dataset. NO OTHER SQL statements have been implicated in the blocking, only this SQL statement. This is parameterized SQL for which an execution plan is cached in sys.dm_exec_cached_plans. This SPID has an object-level S lock on the claim table, so all UPDATEs/INSERTs to the claim table are also blocked. HOST ID varies. Different web servers are responsible for the blocking sessions. E.g., sometimes we trace back to web server 1, sometimes web server 2. When we trace back to the web server implicated in the blocking, we see the following: There is always some sort of application related error in the Event Log on the web server, linked to the Host ID and Host Process ID from the SQL Session. The error messages vary, usually some sort of SystemOutofMemory. (These error messages seem to be similar to error messages that we have seen in the past without such dramatic consequences. We think was happening before, but didn’t lead to blocking. Why now?) No known problems with the network adapters on either the web servers or the SQL server. (In any event the record set returned by the offending query would be small.) Things ruled out: Indexes are regularly defragmented. Statistics regularly updated. Increased sample size of statistics on claim.primaryclaimid. Forced recompilation of the cached execution plan. Created a compound index with primaryclaimid, claimid. No networking problems. No known issues on the web server. No changes to application software on web servers. We hypothesize that the chain of events goes something like this: Web server process submits SQL above. SQL server executes the SQL, during which it acquires a lock on the claim table. Web server process gets an error and dies. SQL server session is hung waiting for the web server process to read the data set. SQL Server sessions that need to get X locks on parts of the claim table (anyone processing claims) are blocked by the lock on the claim table and remain blocked until they all hit the application time out. Any suggestions for troubleshooting while waiting for the vendor's assistance would be most welcome. Is there a way to force SQL Server to lock at the row/page level for this particular SQL statement only? Is there a way to set a threshold on ASYNC_NETWORK_IO waits only?

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  • jQuery Time Entry with Time Navigation Keys

    - by Rick Strahl
    So, how do you display time values in your Web applications? Displaying date AND time values in applications is lot less standardized than date display only. While date input has become fairly universal with various date picker controls available, time entry continues to be a bit of a non-standardized. In my own applications I tend to use the jQuery UI DatePicker control for date entries and it works well for that. Here's an example: The date entry portion is well defined and it makes perfect sense to have a calendar pop up so you can pick a date from a rich UI when necessary. However, time values are much less obvious when it comes to displaying a UI or even just making time entries more useful. There are a slew of time picker controls available but other than adding some visual glitz, they are not really making time entry any easier. Part of the reason for this is that time entry is usually pretty simple. Clicking on a dropdown of any sort and selecting a value from a long scrolling list tends to take more user interaction than just typing 5 characters (7 if am/pm is used). Keystrokes can make Time Entry easier Time entry maybe pretty simple, but I find that adding a few hotkeys to handle date navigation can make it much easier. Specifically it'd be nice to have keys to: Jump to the current time (Now) Increase/decrease minutes Increase/decrease hours The timeKeys jQuery PlugIn Some time ago I created a small plugin to handle this scenario. It's non-visual other than tooltip that pops up when you press ? to display the hotkeys that are available: Try it Online The keys loosely follow the ancient Quicken convention of using the first and last letters of what you're increasing decreasing (ie. H to decrease, R to increase hours and + and - for the base unit or minutes here). All navigation happens via the keystrokes shown above, so it's all non-visual, which I think is the most efficient way to deal with dates. To hook up the plug-in, start with the textbox:<input type="text" id="txtTime" name="txtTime" value="12:05 pm" title="press ? for time options" /> Note the title which might be useful to alert people using the field that additional functionality is available. To hook up the plugin code is as simple as:$("#txtTime").timeKeys(); You essentially tie the plugin to any text box control. OptionsThe syntax for timeKeys allows for an options map parameter:$(selector).timeKeys(options); Options are passed as a parameter map object which can have the following properties: timeFormatYou can pass in a format string that allows you to format the date. The default is "hh:mm t" which is US time format that shows a 12 hour clock with am/pm. Alternately you can pass in "HH:mm" which uses 24 hour time. HH, hh, mm and t are translated in the format string - you can arrange the format as you see fit. callbackYou can also specify a callback function that is called when the date value has been set. This allows you to either re-format the date or perform post processing (such as displaying highlight if it's after a certain hour for example). Here's another example that uses both options:$("#txtTime").timeKeys({ timeFormat: "HH:mm", callback: function (time) { showStatus("new time is: " + time.toString() + " " + $(this).val() ); } }); The plugin code itself is fairly simple. It hooks the keydown event and checks for the various keys that affect time navigation which is straight forward. The bulk of the code however deals with parsing the time value and formatting the output using a Time class that implements parsing, formatting and time navigation methods. Here's the code for the timeKeys jQuery plug-in:/// <reference path="jquery.js" /> /// <reference path="ww.jquery.js" /> (function ($) { $.fn.timeKeys = function (options) { /// <summary> /// Attaches a set of hotkeys to time fields /// + Add minute - subtract minute /// H Subtract Hour R Add houR /// ? Show keys /// </summary> /// <param name="options" type="object"> /// Options: /// timeFormat: "hh:mm t" by default HH:mm alternate /// callback: callback handler after time assignment /// </param> /// <example> /// var proxy = new ServiceProxy("JsonStockService.svc/"); /// proxy.invoke("GetStockQuote",{symbol:"msft"},function(quote) { alert(result.LastPrice); },onPageError); ///</example> if (this.length < 1) return this; var opt = { timeFormat: "hh:mm t", callback: null } $.extend(opt, options); return this.keydown(function (e) { var $el = $(this); var time = new Time($el.val()); //alert($(this).val() + " " + time.toString() + " " + time.date.toString()); switch (e.keyCode) { case 78: // [N]ow time = new Time(new Date()); break; case 109: case 189: // - time.addMinutes(-1); break; case 107: case 187: // + time.addMinutes(1); break; case 72: //H time.addHours(-1); break; case 82: //R time.addHours(1); break; case 191: // ? if (e.shiftKey) $(this).tooltip("<b>N</b> Now<br/><b>+</b> add minute<br /><b>-</b> subtract minute<br /><b>H</b> Subtract Hour<br /><b>R</b> add hour", 4000, { isHtml: true }); return false; default: return true; } $el.val(time.toString(opt.timeFormat)); if (opt.callback) { // call async and set context in this element setTimeout(function () { opt.callback.call($el.get(0), time) }, 1); } return false; }); } Time = function (time, format) { /// <summary> /// Time object that can parse and format /// a time values. /// </summary> /// <param name="time" type="object"> /// A time value as a string (12:15pm or 23:01), a Date object /// or time value. /// /// </param> /// <param name="format" type="string"> /// Time format string: /// HH:mm (23:01) /// hh:mm t (11:01 pm) /// </param> /// <example> /// var time = new Time( new Date()); /// time.addHours(5); /// time.addMinutes(10); /// var s = time.toString(); /// /// var time2 = new Time(s); // parse with constructor /// var t = time2.parse("10:15 pm"); // parse with .parse() method /// alert( t.hours + " " + t.mins + " " + t.ampm + " " + t.hours25) ///</example> var _I = this; this.date = new Date(); this.timeFormat = "hh:mm t"; if (format) this.timeFormat = format; this.parse = function (time) { /// <summary> /// Parses time value from a Date object, or string in format of: /// 12:12pm or 23:01 /// </summary> /// <param name="time" type="any"> /// A time value as a string (12:15pm or 23:01), a Date object /// or time value. /// /// </param> if (!time) return null; // Date if (time.getDate) { var t = {}; var d = time; t.hours24 = d.getHours(); t.mins = d.getMinutes(); t.ampm = "am"; if (t.hours24 > 11) { t.ampm = "pm"; if (t.hours24 > 12) t.hours = t.hours24 - 12; } time = t; } if (typeof (time) == "string") { var parts = time.split(":"); if (parts < 2) return null; var time = {}; time.hours = parts[0] * 1; time.hours24 = time.hours; time.mins = parts[1].toLowerCase(); if (time.mins.indexOf("am") > -1) { time.ampm = "am"; time.mins = time.mins.replace("am", ""); if (time.hours == 12) time.hours24 = 0; } else if (time.mins.indexOf("pm") > -1) { time.ampm = "pm"; time.mins = time.mins.replace("pm", ""); if (time.hours < 12) time.hours24 = time.hours + 12; } time.mins = time.mins * 1; } _I.date.setMinutes(time.mins); _I.date.setHours(time.hours24); return time; }; this.addMinutes = function (mins) { /// <summary> /// adds minutes to the internally stored time value. /// </summary> /// <param name="mins" type="number"> /// number of minutes to add to the date /// </param> _I.date.setMinutes(_I.date.getMinutes() + mins); } this.addHours = function (hours) { /// <summary> /// adds hours the internally stored time value. /// </summary> /// <param name="hours" type="number"> /// number of hours to add to the date /// </param> _I.date.setHours(_I.date.getHours() + hours); } this.getTime = function () { /// <summary> /// returns a time structure from the currently /// stored time value. /// Properties: hours, hours24, mins, ampm /// </summary> return new Time(new Date()); h } this.toString = function (format) { /// <summary> /// returns a short time string for the internal date /// formats: 12:12 pm or 23:12 /// </summary> /// <param name="format" type="string"> /// optional format string for date /// HH:mm, hh:mm t /// </param> if (!format) format = _I.timeFormat; var hours = _I.date.getHours(); if (format.indexOf("t") > -1) { if (hours > 11) format = format.replace("t", "pm") else format = format.replace("t", "am") } if (format.indexOf("HH") > -1) format = format.replace("HH", hours.toString().padL(2, "0")); if (format.indexOf("hh") > -1) { if (hours > 12) hours -= 12; if (hours == 0) hours = 12; format = format.replace("hh", hours.toString().padL(2, "0")); } if (format.indexOf("mm") > -1) format = format.replace("mm", _I.date.getMinutes().toString().padL(2, "0")); return format; } // construction if (time) this.time = this.parse(time); } String.prototype.padL = function (width, pad) { if (!width || width < 1) return this; if (!pad) pad = " "; var length = width - this.length if (length < 1) return this.substr(0, width); return (String.repeat(pad, length) + this).substr(0, width); } String.repeat = function (chr, count) { var str = ""; for (var x = 0; x < count; x++) { str += chr }; return str; } })(jQuery); The plugin consists of the actual plugin and the Time class which handles parsing and formatting of the time value via the .parse() and .toString() methods. Code like this always ends up taking up more effort than the actual logic unfortunately. There are libraries out there that can handle this like datejs or even ww.jquery.js (which is what I use) but to keep the code self contained for this post the plugin doesn't rely on external code. There's one optional exception: The code as is has one dependency on ww.jquery.js  for the tooltip plugin that provides the small popup for all the hotkeys available. You can replace that code with some other mechanism to display hotkeys or simply remove it since that behavior is optional. While we're at it: A jQuery dateKeys plugIn Although date entry tends to be much better served with drop down calendars to pick dates from, often it's also easier to pick dates using a few simple hotkeys. Navigation that uses + - for days and M and H for MontH navigation, Y and R for YeaR navigation are a quick way to enter dates without having to resort to using a mouse and clicking around to what you want to find. Note that this plugin does have a dependency on ww.jquery.js for the date formatting functionality.$.fn.dateKeys = function (options) { /// <summary> /// Attaches a set of hotkeys to date 'fields' /// + Add day - subtract day /// M Subtract Month H Add montH /// Y Subtract Year R Add yeaR /// ? Show keys /// </summary> /// <param name="options" type="object"> /// Options: /// dateFormat: "MM/dd/yyyy" by default "MMM dd, yyyy /// callback: callback handler after date assignment /// </param> /// <example> /// var proxy = new ServiceProxy("JsonStockService.svc/"); /// proxy.invoke("GetStockQuote",{symbol:"msft"},function(quote) { alert(result.LastPrice); },onPageError); ///</example> if (this.length < 1) return this; var opt = { dateFormat: "MM/dd/yyyy", callback: null }; $.extend(opt, options); return this.keydown(function (e) { var $el = $(this); var d = new Date($el.val()); if (!d) d = new Date(1900, 0, 1, 1, 1); var month = d.getMonth(); var year = d.getFullYear(); var day = d.getDate(); switch (e.keyCode) { case 84: // [T]oday d = new Date(); break; case 109: case 189: d = new Date(year, month, day - 1); break; case 107: case 187: d = new Date(year, month, day + 1); break; case 77: //M d = new Date(year, month - 1, day); break; case 72: //H d = new Date(year, month + 1, day); break; case 191: // ? if (e.shiftKey) $el.tooltip("<b>T</b> Today<br/><b>+</b> add day<br /><b>-</b> subtract day<br /><b>M</b> subtract Month<br /><b>H</b> add montH<br/><b>Y</b> subtract Year<br/><b>R</b> add yeaR", 5000, { isHtml: true }); return false; default: return true; } $el.val(d.formatDate(opt.dateFormat)); if (opt.callback) // call async setTimeout(function () { opt.callback.call($el.get(0),d); }, 10); return false; }); } The logic for this plugin is similar to the timeKeys plugin, but it's a little simpler as it tries to directly parse the date value from a string via new Date(inputString). As mentioned it also uses a helper function from ww.jquery.js to format dates which removes the logic to perform date formatting manually which again reduces the size of the code. And the Key is… I've been using both of these plugins in combination with the jQuery UI datepicker for datetime values and I've found that I rarely actually pop up the date picker any more. It's just so much more efficient to use the hotkeys to navigate dates. It's still nice to have the picker around though - it provides the expected behavior for date entry. For time values however I can't justify the UI overhead of a picker that doesn't make it any easier to pick a time. Most people know how to type in a time value and if they want shortcuts keystrokes easily beat out any pop up UI. Hopefully you'll find this as useful as I have found it for my code. Resources Online Sample Download Sample Project © Rick Strahl, West Wind Technologies, 2005-2011Posted in jQuery  HTML   Tweet (function() { var po = document.createElement('script'); po.type = 'text/javascript'; po.async = true; po.src = 'https://apis.google.com/js/plusone.js'; var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(po, s); })();

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  • Syncing Data with a Server using Silverlight and HTTP Polling Duplex

    - by dwahlin
    Many applications have the need to stay in-sync with data provided by a service. Although web applications typically rely on standard polling techniques to check if data has changed, Silverlight provides several interesting options for keeping an application in-sync that rely on server “push” technologies. A few years back I wrote several blog posts covering different “push” technologies available in Silverlight that rely on sockets or HTTP Polling Duplex. We recently had a project that looked like it could benefit from pushing data from a server to one or more clients so I thought I’d revisit the subject and provide some updates to the original code posted. If you’ve worked with AJAX before in Web applications then you know that until browsers fully support web sockets or other duplex (bi-directional communication) technologies that it’s difficult to keep applications in-sync with a server without relying on polling. The problem with polling is that you have to check for changes on the server on a timed-basis which can often be wasteful and take up unnecessary resources. With server “push” technologies, data can be pushed from the server to the client as it changes. Once the data is received, the client can update the user interface as appropriate. Using “push” technologies allows the client to listen for changes from the data but stay 100% focused on client activities as opposed to worrying about polling and asking the server if anything has changed. Silverlight provides several options for pushing data from a server to a client including sockets, TCP bindings and HTTP Polling Duplex.  Each has its own strengths and weaknesses as far as performance and setup work with HTTP Polling Duplex arguably being the easiest to setup and get going.  In this article I’ll demonstrate how HTTP Polling Duplex can be used in Silverlight 4 applications to push data and show how you can create a WCF server that provides an HTTP Polling Duplex binding that a Silverlight client can consume.   What is HTTP Polling Duplex? Technologies that allow data to be pushed from a server to a client rely on duplex functionality. Duplex (or bi-directional) communication allows data to be passed in both directions.  A client can call a service and the server can call the client. HTTP Polling Duplex (as its name implies) allows a server to communicate with a client without forcing the client to constantly poll the server. It has the benefit of being able to run on port 80 making setup a breeze compared to the other options which require specific ports to be used and cross-domain policy files to be exposed on port 943 (as with sockets and TCP bindings). Having said that, if you’re looking for the best speed possible then sockets and TCP bindings are the way to go. But, they’re not the only game in town when it comes to duplex communication. The first time I heard about HTTP Polling Duplex (initially available in Silverlight 2) I wasn’t exactly sure how it was any better than standard polling used in AJAX applications. I read the Silverlight SDK, looked at various resources and generally found the following definition unhelpful as far as understanding the actual benefits that HTTP Polling Duplex provided: "The Silverlight client periodically polls the service on the network layer, and checks for any new messages that the service wants to send on the callback channel. The service queues all messages sent on the client callback channel and delivers them to the client when the client polls the service." Although the previous definition explained the overall process, it sounded as if standard polling was used. Fortunately, Microsoft’s Scott Guthrie provided me with a more clear definition several years back that explains the benefits provided by HTTP Polling Duplex quite well (used with his permission): "The [HTTP Polling Duplex] duplex support does use polling in the background to implement notifications – although the way it does it is different than manual polling. It initiates a network request, and then the request is effectively “put to sleep” waiting for the server to respond (it doesn’t come back immediately). The server then keeps the connection open but not active until it has something to send back (or the connection times out after 90 seconds – at which point the duplex client will connect again and wait). This way you are avoiding hitting the server repeatedly – but still get an immediate response when there is data to send." After hearing Scott’s definition the light bulb went on and it all made sense. A client makes a request to a server to check for changes, but instead of the request returning immediately, it parks itself on the server and waits for data. It’s kind of like waiting to pick up a pizza at the store. Instead of calling the store over and over to check the status, you sit in the store and wait until the pizza (the request data) is ready. Once it’s ready you take it back home (to the client). This technique provides a lot of efficiency gains over standard polling techniques even though it does use some polling of its own as a request is initially made from a client to a server. So how do you implement HTTP Polling Duplex in your Silverlight applications? Let’s take a look at the process by starting with the server. Creating an HTTP Polling Duplex WCF Service Creating a WCF service that exposes an HTTP Polling Duplex binding is straightforward as far as coding goes. Add some one way operations into an interface, create a client callback interface and you’re ready to go. The most challenging part comes into play when configuring the service to properly support the necessary binding and that’s more of a cut and paste operation once you know the configuration code to use. To create an HTTP Polling Duplex service you’ll need to expose server-side and client-side interfaces and reference the System.ServiceModel.PollingDuplex assembly (located at C:\Program Files (x86)\Microsoft SDKs\Silverlight\v4.0\Libraries\Server on my machine) in the server project. For the demo application I upgraded a basketball simulation service to support the latest polling duplex assemblies. The service simulates a simple basketball game using a Game class and pushes information about the game such as score, fouls, shots and more to the client as the game changes over time. Before jumping too far into the game push service, it’s important to discuss two interfaces used by the service to communicate in a bi-directional manner. The first is called IGameStreamService and defines the methods/operations that the client can call on the server (see Listing 1). The second is IGameStreamClient which defines the callback methods that a server can use to communicate with a client (see Listing 2).   [ServiceContract(Namespace = "Silverlight", CallbackContract = typeof(IGameStreamClient))] public interface IGameStreamService { [OperationContract(IsOneWay = true)] void GetTeamData(); } Listing 1. The IGameStreamService interface defines server operations that can be called on the server.   [ServiceContract] public interface IGameStreamClient { [OperationContract(IsOneWay = true)] void ReceiveTeamData(List<Team> teamData); [OperationContract(IsOneWay = true, AsyncPattern=true)] IAsyncResult BeginReceiveGameData(GameData gameData, AsyncCallback callback, object state); void EndReceiveGameData(IAsyncResult result); } Listing 2. The IGameStreamClient interfaces defines client operations that a server can call.   The IGameStreamService interface is decorated with the standard ServiceContract attribute but also contains a value for the CallbackContract property.  This property is used to define the interface that the client will expose (IGameStreamClient in this example) and use to receive data pushed from the service. Notice that each OperationContract attribute in both interfaces sets the IsOneWay property to true. This means that the operation can be called and passed data as appropriate, however, no data will be passed back. Instead, data will be pushed back to the client as it’s available.  Looking through the IGameStreamService interface you can see that the client can request team data whereas the IGameStreamClient interface allows team and game data to be received by the client. One interesting point about the IGameStreamClient interface is the inclusion of the AsyncPattern property on the BeginReceiveGameData operation. I initially created this operation as a standard one way operation and it worked most of the time. However, as I disconnected clients and reconnected new ones game data wasn’t being passed properly. After researching the problem more I realized that because the service could take up to 7 seconds to return game data, things were getting hung up. By setting the AsyncPattern property to true on the BeginReceivedGameData operation and providing a corresponding EndReceiveGameData operation I was able to get around this problem and get everything running properly. I’ll provide more details on the implementation of these two methods later in this post. Once the interfaces were created I moved on to the game service class. The first order of business was to create a class that implemented the IGameStreamService interface. Since the service can be used by multiple clients wanting game data I added the ServiceBehavior attribute to the class definition so that I could set its InstanceContextMode to InstanceContextMode.Single (in effect creating a Singleton service object). Listing 3 shows the game service class as well as its fields and constructor.   [ServiceBehavior(ConcurrencyMode = ConcurrencyMode.Multiple, InstanceContextMode = InstanceContextMode.Single)] public class GameStreamService : IGameStreamService { object _Key = new object(); Game _Game = null; Timer _Timer = null; Random _Random = null; Dictionary<string, IGameStreamClient> _ClientCallbacks = new Dictionary<string, IGameStreamClient>(); static AsyncCallback _ReceiveGameDataCompleted = new AsyncCallback(ReceiveGameDataCompleted); public GameStreamService() { _Game = new Game(); _Timer = new Timer { Enabled = false, Interval = 2000, AutoReset = true }; _Timer.Elapsed += new ElapsedEventHandler(_Timer_Elapsed); _Timer.Start(); _Random = new Random(); }} Listing 3. The GameStreamService implements the IGameStreamService interface which defines a callback contract that allows the service class to push data back to the client. By implementing the IGameStreamService interface, GameStreamService must supply a GetTeamData() method which is responsible for supplying information about the teams that are playing as well as individual players.  GetTeamData() also acts as a client subscription method that tracks clients wanting to receive game data.  Listing 4 shows the GetTeamData() method. public void GetTeamData() { //Get client callback channel var context = OperationContext.Current; var sessionID = context.SessionId; var currClient = context.GetCallbackChannel<IGameStreamClient>(); context.Channel.Faulted += Disconnect; context.Channel.Closed += Disconnect; IGameStreamClient client; if (!_ClientCallbacks.TryGetValue(sessionID, out client)) { lock (_Key) { _ClientCallbacks[sessionID] = currClient; } } currClient.ReceiveTeamData(_Game.GetTeamData()); //Start timer which when fired sends updated score information to client if (!_Timer.Enabled) { _Timer.Enabled = true; } } Listing 4. The GetTeamData() method subscribes a given client to the game service and returns. The key the line of code in the GetTeamData() method is the call to GetCallbackChannel<IGameStreamClient>().  This method is responsible for accessing the calling client’s callback channel. The callback channel is defined by the IGameStreamClient interface shown earlier in Listing 2 and used by the server to communicate with the client. Before passing team data back to the client, GetTeamData() grabs the client’s session ID and checks if it already exists in the _ClientCallbacks dictionary object used to track clients wanting callbacks from the server. If the client doesn’t exist it adds it into the collection. It then pushes team data from the Game class back to the client by calling ReceiveTeamData().  Since the service simulates a basketball game, a timer is then started if it’s not already enabled which is then used to randomly send data to the client. When the timer fires, game data is pushed down to the client. Listing 5 shows the _Timer_Elapsed() method that is called when the timer fires as well as the SendGameData() method used to send data to the client. void _Timer_Elapsed(object sender, ElapsedEventArgs e) { int interval = _Random.Next(3000, 7000); lock (_Key) { _Timer.Interval = interval; _Timer.Enabled = false; } SendGameData(_Game.GetGameData()); } private void SendGameData(GameData gameData) { var cbs = _ClientCallbacks.Where(cb => ((IContextChannel)cb.Value).State == CommunicationState.Opened); for (int i = 0; i < cbs.Count(); i++) { var cb = cbs.ElementAt(i).Value; try { cb.BeginReceiveGameData(gameData, _ReceiveGameDataCompleted, cb); } catch (TimeoutException texp) { //Log timeout error } catch (CommunicationException cexp) { //Log communication error } } lock (_Key) _Timer.Enabled = true; } private static void ReceiveGameDataCompleted(IAsyncResult result) { try { ((IGameStreamClient)(result.AsyncState)).EndReceiveGameData(result); } catch (CommunicationException) { // empty } catch (TimeoutException) { // empty } } LIsting 5. _Timer_Elapsed is used to simulate time in a basketball game. When _Timer_Elapsed() fires the SendGameData() method is called which iterates through the clients wanting to be notified of changes. As each client is identified, their respective BeginReceiveGameData() method is called which ultimately pushes game data down to the client. Recall that this method was defined in the client callback interface named IGameStreamClient shown earlier in Listing 2. Notice that BeginReceiveGameData() accepts _ReceiveGameDataCompleted as its second parameter (an AsyncCallback delegate defined in the service class) and passes the client callback as the third parameter. The initial version of the sample application had a standard ReceiveGameData() method in the client callback interface. However, sometimes the client callbacks would work properly and sometimes they wouldn’t which was a little baffling at first glance. After some investigation I realized that I needed to implement an asynchronous pattern for client callbacks to work properly since 3 – 7 second delays are occurring as a result of the timer. Once I added the BeginReceiveGameData() and ReceiveGameDataCompleted() methods everything worked properly since each call was handled in an asynchronous manner. The final task that had to be completed to get the server working properly with HTTP Polling Duplex was adding configuration code into web.config. In the interest of brevity I won’t post all of the code here since the sample application includes everything you need. However, Listing 6 shows the key configuration code to handle creating a custom binding named pollingDuplexBinding and associate it with the service’s endpoint.   <bindings> <customBinding> <binding name="pollingDuplexBinding"> <binaryMessageEncoding /> <pollingDuplex maxPendingSessions="2147483647" maxPendingMessagesPerSession="2147483647" inactivityTimeout="02:00:00" serverPollTimeout="00:05:00"/> <httpTransport /> </binding> </customBinding> </bindings> <services> <service name="GameService.GameStreamService" behaviorConfiguration="GameStreamServiceBehavior"> <endpoint address="" binding="customBinding" bindingConfiguration="pollingDuplexBinding" contract="GameService.IGameStreamService"/> <endpoint address="mex" binding="mexHttpBinding" contract="IMetadataExchange" /> </service> </services>   Listing 6. Configuring an HTTP Polling Duplex binding in web.config and associating an endpoint with it. Calling the Service and Receiving “Pushed” Data Calling the service and handling data that is pushed from the server is a simple and straightforward process in Silverlight. Since the service is configured with a MEX endpoint and exposes a WSDL file, you can right-click on the Silverlight project and select the standard Add Service Reference item. After the web service proxy is created you may notice that the ServiceReferences.ClientConfig file only contains an empty configuration element instead of the normal configuration elements created when creating a standard WCF proxy. You can certainly update the file if you want to read from it at runtime but for the sample application I fed the service URI directly to the service proxy as shown next: var address = new EndpointAddress("http://localhost.:5661/GameStreamService.svc"); var binding = new PollingDuplexHttpBinding(); _Proxy = new GameStreamServiceClient(binding, address); _Proxy.ReceiveTeamDataReceived += _Proxy_ReceiveTeamDataReceived; _Proxy.ReceiveGameDataReceived += _Proxy_ReceiveGameDataReceived; _Proxy.GetTeamDataAsync(); This code creates the proxy and passes the endpoint address and binding to use to its constructor. It then wires the different receive events to callback methods and calls GetTeamDataAsync().  Calling GetTeamDataAsync() causes the server to store the client in the server-side dictionary collection mentioned earlier so that it can receive data that is pushed.  As the server-side timer fires and game data is pushed to the client, the user interface is updated as shown in Listing 7. Listing 8 shows the _Proxy_ReceiveGameDataReceived() method responsible for handling the data and calling UpdateGameData() to process it.   Listing 7. The Silverlight interface. Game data is pushed from the server to the client using HTTP Polling Duplex. void _Proxy_ReceiveGameDataReceived(object sender, ReceiveGameDataReceivedEventArgs e) { UpdateGameData(e.gameData); } private void UpdateGameData(GameData gameData) { //Update Score this.tbTeam1Score.Text = gameData.Team1Score.ToString(); this.tbTeam2Score.Text = gameData.Team2Score.ToString(); //Update ball visibility if (gameData.Action != ActionsEnum.Foul) { if (tbTeam1.Text == gameData.TeamOnOffense) { AnimateBall(this.BB1, this.BB2); } else //Team 2 { AnimateBall(this.BB2, this.BB1); } } if (this.lbActions.Items.Count > 9) this.lbActions.Items.Clear(); this.lbActions.Items.Add(gameData.LastAction); if (this.lbActions.Visibility == Visibility.Collapsed) this.lbActions.Visibility = Visibility.Visible; } private void AnimateBall(Image onBall, Image offBall) { this.FadeIn.Stop(); Storyboard.SetTarget(this.FadeInAnimation, onBall); Storyboard.SetTarget(this.FadeOutAnimation, offBall); this.FadeIn.Begin(); } Listing 8. As the server pushes game data, the client’s _Proxy_ReceiveGameDataReceived() method is called to process the data. In a real-life application I’d go with a ViewModel class to handle retrieving team data, setup data bindings and handle data that is pushed from the server. However, for the sample application I wanted to focus on HTTP Polling Duplex and keep things as simple as possible.   Summary Silverlight supports three options when duplex communication is required in an application including TCP bindins, sockets and HTTP Polling Duplex. In this post you’ve seen how HTTP Polling Duplex interfaces can be created and implemented on the server as well as how they can be consumed by a Silverlight client. HTTP Polling Duplex provides a nice way to “push” data from a server while still allowing the data to flow over port 80 or another port of your choice.   Sample Application Download

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  • Learning resources for working with POCO entities in EF 4.0

    - by boghydan
    Here are some links that can help you start working with POCO entities in EF 4.0: ADO.NET Team blog: - Working with POCO objects: http://blogs.msdn.com/adonet/archive/2009/05/21/poco-in-the-entity-framework-part-1-the-experience.aspx - Proxy objects for POCO entities: http://blogs.msdn.com/adonet/archive/2009/12/22/poco-proxies-part-1.aspx MSDN Library: - Working with POCO  http://msdn.microsoft.com/en-us/library/dd456853.aspx - T4 editor for POCO generator can be downloaded from here: http://visualstudiogallery.msdn.microsoft.com/en-us/60297607-5fd4-4da4-97e1-3715e90c1a23

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  • How does a website latency simulator work

    - by nighthawk457
    Sites like webpagetest allow users to enter a website url and a test location, to run a speed test on the site from multiple locations using real browsers. Can anyone give me a basic idea of how sites like this work? You also have plugin's like Aptimize latency simulator or charles web debugging proxy app, that simulate the delay while accessing a site from different locations. I am assuming since these are plugin's these function in a different way. How do these plugin's work ?

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  • Tips on ensuring Model Quality

    - by [email protected]
    Given enough data that represents well the domain and models that reflect exactly the decision being optimized, models usually provide good predictions that ensure lift. Nevertheless, sometimes the modeling situation is less than ideal. In this blog entry we explore the problems found in a few such situations and how to avoid them.1 - The Model does not reflect the problem you are trying to solveFor example, you may be trying to solve the problem: "What product should I recommend to this customer" but your model learns on the problem: "Given that a customer has acquired our products, what is the likelihood for each product". In this case the model you built may be too far of a proxy for the problem you are really trying to solve. What you could do in this case is try to build a model based on the result from recommendations of products to customers. If there is not enough data from actual recommendations, you could use a hybrid approach in which you would use the [bad] proxy model until the recommendation model converges.2 - Data is not predictive enoughIf the inputs are not correlated with the output then the models may be unable to provide good predictions. For example, if the input is the phase of the moon and the weather and the output is what car did the customer buy, there may be no correlations found. In this case you should see a low quality model.The solution in this case is to include more relevant inputs.3 - Not enough cases seenIf the data learned does not include enough cases, at least 200 positive examples for each output, then the quality of recommendations may be low. The obvious solution is to include more data records. If this is not possible, then it may be possible to build a model based on the characteristics of the output choices rather than the choices themselves. For example, instead of using products as output, use the product category, price and brand name, and then combine these models.4 - Output leaking into input giving the false impression of good quality modelsIf the input data in the training includes values that have changed or are available only because the output happened, then you will find some strong correlations between the input and the output, but these strong correlations do not reflect the data that you will have available at decision (prediction) time. For example, if you are building a model to predict whether a web site visitor will succeed in registering, and the input includes the variable DaysSinceRegistration, and you learn when this variable has already been set, you will probably see a big correlation between having a Zero (or one) in this variable and the fact that registration was successful.The solution is to remove these variables from the input or make sure they reflect the value as of the time of decision and not after the result is known. 

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