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• VMware vSphere cluster design for site redundancy

  - by Stefan Radovanovici

  I have a question about the best design for site redudancy when using vSphere clusters. A bit of background info about our situation first though. We are a medium-sized company with two main offices, located in different countries. Our networks are linked by a Layer2 150Mbps leased line which is currently underused. We have a variety of services running for internal use within the company, some on physycal servers and some on existing vSphere clusters. In our department we also run several services (almost all running under various forms of Linux) like NTP, Syslog, jump servers, monitoring servers and so on. We have now the requirement that those servers need to be redundant within each location (which they are not at the moment) and also site redudant (which they are to some extent, the servers are duplicated in the 2nd location with configurations kept in sync via various methods at the application layer). There is no SAN available for us, at least not something that we can use at the moment. Cost is also an issue. While we do have some budget available for this, we can't afford to buy SANs for both locations for example. I looked at the VSA feature and it seems that this could be something for us but I am unsure how to solve the site-redudancy requirement. At the moment for testing purposes I am setting up in a lab a vSphere 5 with VSA on two ESXi hosts. I am currently using the Essentials Plus kit with VSA license, which allows me to build a VSA cluster on up to 3 hosts, together with a vCenter license to manage them. The hosts each have two dual-port network cards and two 600GB drives, running in Raid1. Hardware-wise this will be enough for us to run the all the services we need as VMs and will provide redundandcy within the site. At the moment I see only two option to have site redundancy: build an identical VSA cluter in the second location and keep the various services sync'ed at application layer (database sync, rsync and so on). simply move one of the hosts from the existing cluster to the second location, basically having the VSA cluster span the 150Mbps link between the sites. I would very much prefer the second option but I am unsure how well it'll work, if it can work at all. Technically it should, we can span the needed VLANs across the leased line and have them available in the second location. The advantage would be that we don't need to worry at all about sync'ing databases and the like. But I have the feeling that the bandwidth will not be enough, I have no way of knowing how much traffic will the VSA cluster generate between the hosts. I realize that this will most likely depend on the individual usage of the VMs but still, I have no idea how VSA replicates data between the ESXi hosts. Are these my only options or can my goals be achieved in some other way ? Is there perhaps a way to have some sort of "cold stand by" cluster in the second location where the VMs would be sync'ed once per night from the main location ? The idea is that in case the first site becomes unavailable, we would be able to bring all those VMs online there. We would be ok with the data being 1 day old. Any answers are appreciated. Best regards, Stefan

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• Pushing DNSSEC updates with offline keys

  - by eggyal

  In a non-professional capacity, I look after the DNS of some 18 domains: mostly personal/vanity domains for immediate family. I outsource the whole shebang to an inexpensive managed hosting provider with a web interface through which I manage the zones; since the provider also offers DNSSEC, I have successfully deployed that too. These domains are so unimportant that an attack targetted against them seems much less likely than a general compromise of my provider's systems, at which point the records of all their customers might be changed to misdirect traffic (perhaps with extremely long TTLs). DNSSEC could protect against such an attack, but only if the zone's private keys are not held by the hosting provider. So, I wonder: how can one keep DNSSEC private keys offline yet still transfer signed zones to an outsourced DNS host? The most obvious answer (to me, at least) is to run one's own shadow/hidden master (from which the provider can slave) and then copy offline-signed zonefiles to the master as required. The problem is that the only machine I (want to*) control is my personal laptop, which usually connects from a typical home ADSL (behind NAT over a dynamically-assigned IP address). Having them slave from that (e.g. with a very long Expiry time on the zone for periods when my laptop is offline/unavailable) would not only require a Dynamic DNS record from which they can slave (if indeed they can slave from a named host rather than a static IP address), but would also involve me running a DNS server on my laptop and opening both it and my home network up to the incoming zone transfer requests: not ideal. I would prefer a much more push-oriented design, whereby my laptop initiates transfer of offline-signed zonefiles/updates to the provider's servers. I looked into whether nsupdate could fit the bill: documentation is a little sketchy, but my testing (with BIND 9.7) suggests it can indeed update DNSSEC zones, but only where the server holds the keys to perform the zone signing; I have not found a way to have it take an update including the relevant RRSIG/NSEC/etc. records and have the server accept them. Is this a supported use-case? If not, I suspect the only solutions which could fit the bill will involve non-DNS-based transfer of the zone updates and would welcome recommendations that are supported by (hopefully inexpensive) hosting providers: SFTP/SCP? rsync? RDBMS replication? Proprietary API? Finally, what would be the practical implications of such a setup? Key rotation is jumping out at me as being an obvious difficulty, especially if my laptop is offline for extended periods. But the zones are extremely stable, so perhaps I could get away with long-lived ZSKs**...? * Whilst I could run a shadow/hidden master on e.g. an outsourced VPS, I dislike the overhead of having to secure / manage / monitor / maintain yet another system; not to mention the additional financial costs of so doing. ** Okay, this would enable a concerted attacker to replay outdated records—but the risk and impact of such are both tolerable in the case of these domains.

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• Issue in nginx proxying to apache

  - by Luis Masuelli

  My current nginx configuration is as follows: specific configuration for (currently two) domains: server { listen 443 ssl; server_name studiotv.service.tebusco.lan phpmyadmin.service.tebusco.lan; ssl_certificate /home/administrador/nginx-confs/ssl/service.tebusco.lan.crt; ssl_certificate_key /home/administrador/nginx-confs/ssl/service.tebusco.lan.key; location / { proxy_pass http://127.0.0.1:8180; proxy_set_header Host $http_host:8180; } } default configuration for unmatched ssl connections: server { listen 443 default ssl; ssl_certificate /home/administrador/nginx-confs/ssl/service.tebusco.lan.crt; ssl_certificate_key /home/administrador/nginx-confs/ssl/service.tebusco.lan.key; location / { return 403; } } http configuration: server { listen 80; rewrite ^ https://$host$request_uri? permanent; } The intention is clear: Redirect http traffic to https. Proxy each https:// call from phpmyadmin.service.tebusco.lan and studiotv.service.tebusco.lan to apache2. This includes passing a host header, which is detected. Each unmatched ssl connection must return a 403 in nginx. Does not even reach apache2. In the apache2 side of the life, I have a default site, and a non-default site which will match studiotv.service.tebusco.lan: 000-default.conf file (available and enabled): <VirtualHost 127.0.0.1:8180> # The ServerName directive sets the request scheme, hostname and port that # the server uses to identify itself. This is used when creating # redirection URLs. In the context of virtual hosts, the ServerName # specifies what hostname must appear in the request's Host: header to # match this virtual host. For the default virtual host (this file) this # value is not decisive as it is used as a last resort host regardless. # However, you must set it for any further virtual host explicitly. ServerName localhost ServerAdmin webmaster@localhost DocumentRoot /var/www/html <Directory /var/www/html> Order deny,allow Require all granted </Directory> </VirtualHost> # vim: syntax=apache ts=4 sw=4 sts=4 sr noet studiotv.conf file (available and enabled): <VirtualHost *:8180> ServerName studiotv.service.tebusco.lan ServerAdmin [email protected] DocumentRoot /var/www/studiotv <Directory /var/www/studiotv/> Options -Indexes +FollowSymLinks AllowOverride None Order deny,allow Allow from all Require all granted </Directory> # Available loglevels: trace8, ..., trace1, debug, info, notice, warn, # error, crit, alert, emerg. # It is also possible to configure the loglevel for particular # modules, e.g. #LogLevel info ssl:warn # No usamos ${APACHE_LOG_DIR} sino en su lugar /var/log/<host> ErrorLog /var/log/apache2/studiotv/error.log CustomLog /var/log/apache2/studiotv/access.log combined </VirtualHost> # vim: syntax=apache ts=4 sw=4 sts=4 sr noet However, when I hit the browser with http://studiotv.service.tebusco.lan, the default php page is shown instead. Question: What am I missing? (apache 2.4.7, nginx 1.6.0, ubuntu server 14.04).

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• Static file download from browser breaking in varnish but works fine in Apache

  - by Ron

  I would at first like to thank everyone at serverfault for this great website and I also come to this site while searching in google for various server related issues and setups. I also have an issue today and so I am posting here and hope that the seniors would help me out. I had setup a website on a dedicated server a few days ago and I used Varnish 3 as the frontend to Apache2 on a Debian Lenny server as the traffic was a bit high. There are several static file downloads of around 10-20 MB in size in the website. The website looked fine in the last few days after I setup. I was checking from a 5mbps + broadband connection and the file downloads were also completed in seconds and working fine. But today I realized that on a slow internet connection the file downloads were breaking off. When I tried to download the files from the website using a browser then it broke off after a minute or so. It kept on happening again and again and so it had nothing to do with the internet connection. The internet connection was around 512 kbps and so it was not dial up level speed too but decent speed where files should easily download though not that fast. Then I thought of trying out with the apache backend port and used the port number to check out if the problem occurs. But then on adding the apache port in the static file download url, the files got downloaded easily and did not break even once. I tried it several times to make sure that it was not a coincidence but every time I was using the apache port in the file download url then it was downloading fine while it was breaking each time with the normal link which was routed through Varnish I suppose. So, it seems Varnish has somehow resulted in the broken file downloads. Could anyone give any idea as to why it is happening and how to fix the problem. For more clarification, take this example: Apache backend set on port 8008, Varnish frontend set on port 80 Now when I download say http://mywebsite.com/directory/filename.extension Then the download breaks off after a minute or so. I cannot be sure it is due to the time or size though and I am just assuming. May be some other reason too. But when I download using: http://mywebsite.com:8008/directory/filename.extension Then the file download does not break at all and it gets download fine. So, it seems that varnish is somehow creating the file download breaking and not apache. Does anybody have any idea as to why it is happening and how can it be fixed. Any help would be highly appreciated. And my varnish default.vcl is backend apache { set backend.host = "127.0.0.1"; set backend.port = "8008"; } sub vcl_deliver { remove resp.http.X-Varnish; remove resp.http.Via; remove resp.http.Age; remove resp.http.Server; remove resp.http.X-Powered-By; }

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• How to make XAMPP virtual hosts accessible to VM's and other computers on LAN?

  - by martin's

  XAMPP running on Vista 64 Ultimate dev machine (don't think it matters). Machine / Browser configuration Safari, Firefox, Chrome and IE9 on dev machine IE7 and IE8 on separate XP Pro VM's (VMWare on dev machine) IE10 and Chrome on Windows 8 VM (VMware on dev machine) Safari, Firefox and Chrome running on a iMac (same network as dev) Safari, Firefox and Chrome running on a couple of Mac Pro's (same network as dev) IE7, IE8, IE9 running on other PC's on the same network as dev machine Development Configuration Multiple virtual hosts for different projects .local fake TLD for development No firewall restrictions on dev machine for Apache Some sites have .htaccess mapping www to non-www Port 80 is open in the dev machine's firewall Problem XAMPP local home page (http://192.168.1.98/xampp/) can be accessed from everywhere, real or virtual, by IP All .local sites can be accessed from the browsers on the dev machine. All .local sites can be accessed form the browsers in the XP VM's. Some .local sites cannot be accessed from IE10 or Chrome on the W8 VM Sites that cannot be accessed from W8 VM have a minimal .htaccess file No .local sites can be accessed from ANY machine (PC or Mac) on the LAN hosts on dev machine (relevant excerpt) 127.0.0.1 site1.local 127.0.0.1 site2.local 127.0.0.1 site3.local 127.0.0.1 site4.local 127.0.0.1 site5.local 127.0.0.1 site6.local 127.0.0.1 site7.local 127.0.0.1 site8.local 127.0.0.1 site9.local 192.168.1.98 site1.local 192.168.1.98 site2.local 192.168.1.98 site3.local 192.168.1.98 site4.local 192.168.1.98 site5.local 192.168.1.98 site6.local 192.168.1.98 site7.local 192.168.1.98 site8.local 192.168.1.98 site9.local httpd-vhosts.conf on dev machine (relevant excerpt) NameVirtualHost *:80 <VirtualHost *:80> ServerName localhost ServerAlias localhost *.localhost.* DocumentRoot D:/xampp/htdocs </VirtualHost> # ======================================== site1.local <VirtualHost *:80> ServerName site1.local ServerAlias site1.local *.site1.local DocumentRoot D:/xampp-sites/site1/public_html ErrorLog D:/xampp-sites/site1/logs/access.log CustomLog D:/xampp-sites/site1/logs/error.log combined <Directory D:/xampp-sites/site1> Options Indexes FollowSymLinks AllowOverride All Require all granted </Directory> </VirtualHost> NOTE: The above <VirtualHost *:80> block is repeated for each of the nine virtual hosts in the file, no sense in posting it here. hosts on all VM's and physical machines on the network (relevant excerpt) 127.0.0.1 localhost ::1 localhost 192.168.1.98 site1.local 192.168.1.98 site2.local 192.168.1.98 site3.local 192.168.1.98 site4.local 192.168.1.98 site5.local 192.168.1.98 site6.local 192.168.1.98 site7.local 192.168.1.98 site8.local 192.168.1.98 site9.local None of the VM's have any firewall blocks on http traffic. They can reach any site on the real Internet. The same is true of the real machines on the network. The biggest puzzle perhaps is that the W8 VM actually DOES reach some of the virtual hosts. It does NOT reach site2, site6 and site 9, all of which have this minimal .htaccess file. .htaccess file <IfModule mod_rewrite.c> RewriteEngine On RewriteCond %{HTTP_HOST} !^www\. RewriteRule ^(.*)$ http://www.%{HTTP_HOST}/$1 [R=301,L] </IfModule> Adding this file to any of the virtual hosts that do work on the W8 VM will break the site (only for W8 VM, not the XP VM's) and require a cache flush on the W8 VM before it will see the site again after deleting the file. Regardless of whether a .htaccess file exists or not, no machine on the same LAN can access anything other than the XAMPP home page via IP. Even with hosts files on all machines. I can ping any virtual host from any machine on the network and get a response from the correct IP address. I can't see anything in out Netgear router that might prevent one machine from reaching the other. Besides, once the local hosts file resolves to an ip address that's all that goes out onto the local network. I've gone through an extensive number of posts on both SO and as the result of Google searches. I can't say that I have found anything definitive anywhere.

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• How broken is routing strategy that causes a martian packet (so far only) during tracepath?

  - by lkraav

  I believe I've achieved a table that routes packets from and to eth1/192.168.3.x through 192.168.3.1, and packets from and to eth0/192.168.1.x through 192.168.1.1 (helpful source). Question: when doing tracepath from 192.168.3.20 (from within vserver), I'm getting kernel: [318535.927489] martian source 192.168.3.20 from 212.47.223.33, on dev eth0 at or near the target IP, while intermediary hops go without (log below). I don't understand why this packet is arriving on eth0, instead of eth1, even after reading this: Note that you may see packets from non-routable IP addresses when running the traceroute or tracepath commands. While packets cannot be routed to these routers, packets sent between 2 routers only need to know the address of the next hop within the local networks, which could be a non-routable address. Can someone explain that paragraph in human language? Based on short initial trials so far, everything else seems to work without causing martians. Is this contained to the nature of tracepath operation or do I have some other bigger routing problem that will cause work traffic breakage? Side note: is it possible to inspect martian packet with tcpdump or wireshark or anything of the sort? I'm have not been able to get it to show up on my own. vserver-20 / # tracepath -n 212.47.223.33 1: 192.168.3.2 0.064ms pmtu 1500 1: 192.168.3.1 1.076ms 1: 192.168.3.1 1.259ms 2: 90.191.8.2 1.908ms 3: 90.190.134.194 2.595ms 4: 194.126.123.94 2.136ms asymm 5 5: 195.250.170.22 2.266ms asymm 6 6: 212.47.201.86 2.390ms asymm 7 7: no reply 8: no reply 9: no reply ^C Host routing: $ sudo ip addr 1: lo: <LOOPBACK,UP,LOWER_UP> mtu 16436 qdisc noqueue state UNKNOWN link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00 inet 127.0.0.1/8 scope host lo 2: sit0: <NOARP> mtu 1480 qdisc noop state DOWN link/sit 0.0.0.0 brd 0.0.0.0 3: eth0: <BROADCAST,MULTICAST,PROMISC,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000 link/ether 00:24:1d:de:b3:5d brd ff:ff:ff:ff:ff:ff inet 192.168.1.2/24 scope global eth0 4: eth1: <BROADCAST,MULTICAST,PROMISC,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000 link/ether 00:0c:46:46:a3:6a brd ff:ff:ff:ff:ff:ff inet 192.168.3.2/27 scope global eth1 inet 192.168.3.20/27 brd 192.168.3.31 scope global secondary eth1 # linux-vserver instance $ sudo ip route default via 192.168.1.1 dev eth0 metric 3 unreachable 127.0.0.0/8 scope host 192.168.1.0/24 dev eth0 proto kernel scope link src 192.168.1.2 192.168.3.0/27 dev eth1 proto kernel scope link src 192.168.3.2 $ sudo ip rule 0: from all lookup local 32764: from all to 192.168.3.0/27 lookup dmz 32765: from 192.168.3.0/27 lookup dmz 32766: from all lookup main 32767: from all lookup default $ sudo ip route show table dmz default via 192.168.3.1 dev eth1 metric 4 192.168.3.0/27 dev eth1 scope link metric 4 Gateway routing # ip route 10.24.0.2 dev tun0 proto kernel scope link src 10.24.0.1 10.24.0.0/24 via 10.24.0.2 dev tun0 192.168.3.0/24 dev br-dmz proto kernel scope link src 192.168.3.1 192.168.1.0/24 dev br-lan proto kernel scope link src 192.168.1.1 $ISP_NET/23 dev eth0.1 proto kernel scope link src $WAN_IP default via $ISP_GW dev eth0.1 Additional background Options for non-virtualized network interface isolation?

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• How do bots access directories on a server that are not DocumentRoot of public IP address? How do I stop them?

  - by tmsimont

  I have a local network set up with apache2 and "named" running on OpenSuse 13.1 Linux. I used the "named" service to use my computer as a domain server. I set up my router to point to ask my computer for domain lookups, so I have a chance to have it rewrite a bunch of domains on my network to its own local IP, 192.168.0.111 This works great. I use virtual host configuration to allow various domains and subdomains (re-routed to the same IP via named) to pull up different directories in my computer. For example: <VirtualHost *:80> ServerName 192.168.0.111 ServerAlias fmb.wa.net DocumentRoot /home/work/wa.net/fmb </VirtualHost> <VirtualHost *:80> ServerName 192.168.0.111 ServerAlias postrecord.wa.net DocumentRoot /home/work/wa.net/postrecord </VirtualHost> <VirtualHost *:80> ServerName 192.168.0.111 ServerAlias cvalley.wa.net DocumentRoot /home/work/wa.net/cvalley_local </VirtualHost> This makes it possible for me to hit cvalley.wa.net from any device in my network and get the site that lives in /home/work/wa.net/cvalley_local I decided to forward port 80 to this computer, so I could share a few development sites with coworkers. I can't control which site they see with the same named service, because they'd have to use my computer as their domain name server... So I added a line like this: <VirtualHost *:80> ServerName 192.168.0.111 ServerAlias MY.IP.XXX.XX DocumentRoot /home/work/wa.net/cvalley </VirtualHost> Where "MY.IP.XXX.XX" is my public IP address. This works as expected, when you hit my IP address from a public network you see the site that lives in /home/work/wa.net/cvalley. The point of confusion that I have is that there are public IP addresses in my logs in other sites. I would have expected it to be impossible to access other sites in my network, unless the public user somehow figured out what I'm calling my ServerAliases, and is mimicing my domain set up... How can public traffic be hitting my other local sites? How can I recreate this kind of access? Here are some examples of public IP's hitting my VirtualHost sites: 162.253.66.76 - - [15/Aug/2014:19:20:47 -0600] "GET /xmlrpc.php HTTP/1.0" 404 1004 "-" "-" 162.253.66.74 - - [16/Aug/2014:10:50:28 -0600] "GET / HTTP/1.0" 200 262 "-" "masscan/1.0 (https://github.com/robertdavidgraham/masscan)" 185.4.227.194 - - [16/Aug/2014:11:16:45 -0600] "GET http://24x7-allrequestsallowed.com/?PHPSESSID=1rysxtj500143WQMVT%5E_NAZ%5BQ HTTP/1.1" 200 262 "-" "-" 101.226.254.138 - - [16/Aug/2014:13:32:14 -0600] "HEAD / HTTP/1.0" 200 - "-" "-" 162.253.66.74 - - [16/Aug/2014:14:26:19 -0600] "GET / HTTP/1.0" 200 262 "-" "masscan/1.0 (https://github.com/robertdavidgraham/masscan)" 212.129.2.119 - - [16/Aug/2014:16:00:51 -0600] "HEAD / HTTP/1.0" 200 - "-" "-" 91.240.163.111 - - [16/Aug/2014:18:34:32 -0600] "GET / HTTP/1.0" 200 262 "-" "masscan/1.0 (https://github.com/robertdavidgraham/masscan)" 162.253.66.74 - - [16/Aug/2014:19:02:53 -0600] "GET / HTTP/1.0" 200 262 "-" "masscan/1.0 (https://github.com/robertdavidgraham/masscan)" 122.226.223.69 - - [17/Aug/2014:05:53:09 -0600] "GET http://www.k2proxy.com//hello.html HTTP/1.1" 404 1006 "-" "Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 6.1; WOW64; Trident/6.0; SLCC2; .NET CLR 2.0.50727; .NET CLR 3.5.30729; .NET CLR 3.0.30729; Media Center PC 6.0; .NET4.0C; .NET4.0E)" ::1 - - [17/Aug/2014:10:19:26 -0600] "OPTIONS * HTTP/1.0" 200 - "-" "Apache/2.4.6 (Linux/SUSE) OpenSSL/1.0.1e PHP/5.4.20 (internal dummy connection)" 162.209.65.196 - - [17/Aug/2014:15:31:53 -0600] "HEAD / HTTP/1.0" 200 - "-" "-" 111.206.199.163 - - [18/Aug/2014:11:12:56 -0600] "HEAD / HTTP/1.0" 200 - "-" "-" 37.187.180.168 - - [18/Aug/2014:15:40:00 -0600] "HEAD / HTTP/1.0" 200 - "-" "-" 62.210.38.226 - - [18/Aug/2014:18:35:16 -0600] "HEAD / HTTP/1.0" 200 - "-" "-" Is there anything that I can do to reliably deny public access by default, but allow it only in one VirtualHost?

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• How to send email from an EC2 instance using GoDaddy's SMTP server?

  - by Matt Greer

  SMTP is a whole new ballgame for me, but I am reading up on it. I am attempting to send email from my EC2 instance using GoDaddy's SMTP server. My domain name is registered through GoDaddy and I have 2 email accounts with them. I can successfully send the email from my dev box no problem. my web.config <system.net> <mailSettings> <smtp from="[email protected]" deliveryMethod="Network"> <network host="smtpout.secureserver.net" clientDomain="mydomain.com" port="25" userName="[email protected]" password="mypassword" defaultCredentials="false" /> </smtp> </mailSettings> </system.net> In my ASP.NET app: MailMessage mailMessage = new MailMessage("[email protected]", recipientEmail, emailSubject, body); mailMessage.IsBodyHtml = false; SmtpClient mailClient = new SmtpClient(); mailClient.Send(mailMessage); Very typical, simple use of System.Net.Mail.SmtpClient. The mail client is picking up the settings from my web.config as expected. From the EC2 instance, the same setup yields: System.Net.Mail.SmtpException: Failure sending mail. ---> System.IO.IOException: Unable to read data from the transport connection: net_io_connectionclosed. at System.Net.Mail.SmtpReplyReaderFactory.ProcessRead(Byte[] buffer, Int32 offset, Int32 read, Boolean readLine) at System.Net.Mail.SmtpReplyReaderFactory.ReadLines(SmtpReplyReader caller, Boolean oneLine) at System.Net.Mail.SmtpReplyReaderFactory.ReadLine(SmtpReplyReader caller) at System.Net.Mail.SmtpConnection.GetConnection(ServicePoint servicePoint) at System.Net.Mail.SmtpClient.Send(MailMessage message) --- End of inner exception stack trace --- I have searched high and low and not found anyone else attempting this. All GoDaddy smtp situations I have found involve people being hosted by GoDaddy using their relay server. Some more info: My EC2 instance is Windows Server 2008 with IIS 7. The app is running in .NET 4 I can successfully use Gmail's SMTP server on the EC2 instance by using their port, setting SmtpClient.EnableSsl to true, and sending the mail through a gmail account. But we want to send the email from an account on our domain. I have port 25 open on both the Windows firewall and Amazon's Security group based firewall. I have played with Wireshark and noticed my SMTP related traffic was talking to ports in the 5,000s, so out of desperation I opened them all up to no avail (then closed them back down) As far as I know my EC2 instance's IP address is not black listed by GoDaddy. I have a feeling I'm just missing something fundamental. I also have a feeling someone is going to recommend I use AuthSmtp or something similar, I'll agree, and have had wasted the past 6 hours :)

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• Problem with Google Analytics for Android : "Dispatcher thinks it finished, but there were 543 faile

  - by PHP_Jedi

  Anyone know how to solve this problem? 03-23 13:03:20.585: WARN/googleanalytics(3430): Problem with socket or streams. 03-23 13:03:20.585: WARN/googleanalytics(3430): java.net.SocketException: Broken pipe 03-23 13:03:20.585: WARN/googleanalytics(3430): at org.apache.harmony.luni.platform.OSNetworkSystem.sendStreamImpl(Native Method) 03-23 13:03:20.585: WARN/googleanalytics(3430): at org.apache.harmony.luni.platform.OSNetworkSystem.sendStream(OSNetworkSystem.java:498) 03-23 13:03:20.585: WARN/googleanalytics(3430): at org.apache.harmony.luni.net.PlainSocketImpl.write(PlainSocketImpl.java:585) 03-23 13:03:20.585: WARN/googleanalytics(3430): at org.apache.harmony.luni.net.SocketOutputStream.write(SocketOutputStream.java:59) 03-23 13:03:20.585: WARN/googleanalytics(3430): at org.apache.http.impl.io.AbstractSessionOutputBuffer.flushBuffer(AbstractSessionOutputBuffer.java:87) 03-23 13:03:20.585: WARN/googleanalytics(3430): at org.apache.http.impl.io.AbstractSessionOutputBuffer.flush(AbstractSessionOutputBuffer.java:94) 03-23 13:03:20.585: WARN/googleanalytics(3430): at org.apache.http.impl.AbstractHttpClientConnection.doFlush(AbstractHttpClientConnection.java:168) 03-23 13:03:20.585: WARN/googleanalytics(3430): at org.apache.http.impl.AbstractHttpClientConnection.flush(AbstractHttpClientConnection.java:173) 03-23 13:03:20.585: WARN/googleanalytics(3430): at com.google.android.apps.analytics.PipelinedRequester.sendRequests(Unknown Source) 03-23 13:03:20.585: WARN/googleanalytics(3430): at com.google.android.apps.analytics.NetworkDispatcher$DispatcherThread$AsyncDispatchTask.dispatchSomePendingEvents(Unknown Source) 03-23 13:03:20.585: WARN/googleanalytics(3430): at com.google.android.apps.analytics.NetworkDispatcher$DispatcherThread$AsyncDispatchTask.run(Unknown Source) 03-23 13:03:20.585: WARN/googleanalytics(3430): at android.os.Handler.handleCallback(Handler.java:587) 03-23 13:03:20.585: WARN/googleanalytics(3430): at android.os.Handler.dispatchMessage(Handler.java:92) 03-23 13:03:20.585: WARN/googleanalytics(3430): at android.os.Looper.loop(Looper.java:123) 03-23 13:03:20.585: WARN/googleanalytics(3430): at android.os.HandlerThread.run(HandlerThread.java:60) 03-23 13:03:21.088: WARN/googleanalytics(3430): Dispatcher thinks it finished, but there were 543 failed events Specially the last line explain why there is lost so much data, as the dispatcher thinks it is done, but have 543 events not dispatched... The application have a good internet connection and there is no problem reaching the app server-side api. I see in analytics that lots of startups and click-events the past few days are lost, even I know the traffic is normal since i can see statistics from the the server api. In the analytics reports I see a day by day under-reporting. So the problems seems to be spreading/growing to all the devices using this application. Im wondering why google does not answer this in their mail-groups - several people have complained about this...well, well... I found this thread relevant: http://stackoverflow.com/questions/682560/java-net-socketexception-broken-pipe But, I'm still not sure if there is anything I can do to fix it or not. If there is nothing I can do to fix it, I guess its not my fault that it got broken. But i got a feeling it is, since the problem got dramatically worse on the last deploy to Android market. Anyone else with experience on Google Analytics for android ?

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• Tactics for using PHP in a high-load site

  - by Ross

  Before you answer this I have never developed anything popular enough to attain high server loads. Treat me as (sigh) an alien that has just landed on the planet, albeit one that knows PHP and a few optimisation techniques. I'm developing a tool in PHP that could attain quite a lot of users, if it works out right. However while I'm fully capable of developing the program I'm pretty much clueless when it comes to making something that can deal with huge traffic. So here's a few questions on it (feel free to turn this question into a resource thread as well). Databases At the moment I plan to use the MySQLi features in PHP5. However how should I setup the databases in relation to users and content? Do I actually need multiple databases? At the moment everything's jumbled into one database - although I've been considering spreading user data to one, actual content to another and finally core site content (template masters etc.) to another. My reasoning behind this is that sending queries to different databases will ease up the load on them as one database = 3 load sources. Also would this still be effective if they were all on the same server? Caching I have a template system that is used to build the pages and swap out variables. Master templates are stored in the database and each time a template is called it's cached copy (a html document) is called. At the moment I have two types of variable in these templates - a static var and a dynamic var. Static vars are usually things like page names, the name of the site - things that don't change often; dynamic vars are things that change on each page load. My question on this: Say I have comments on different articles. Which is a better solution: store the simple comment template and render comments (from a DB call) each time the page is loaded or store a cached copy of the comments page as a html page - each time a comment is added/edited/deleted the page is recached. Finally Does anyone have any tips/pointers for running a high load site on PHP. I'm pretty sure it's a workable language to use - Facebook and Yahoo! give it great precedence - but are there any experiences I should watch out for? Thanks, Ross

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• C# SerialPort - Problems mixing ports with different baud rates.

  - by GrandAdmiral

  Greetings, I have two devices that I would like to connect over a serial interface, but they have incompatible connections. To get around this problem, I connected them both to my PC and I'm working on a C# program that will route traffic on COM port X to COM port Y and vice versa. The program connects to two COM ports. In the data received event handler, I read in incoming data and write it to the other COM port. To do this, I have the following code: private void HandleDataReceived(SerialPort inPort, SerialPort outPort) { byte[] data = new byte[1]; while (inPort.BytesToRead > 0) { // Read the data data[0] = (byte)inPort.ReadByte(); // Write the data if (outPort.IsOpen) { outPort.Write(data, 0, 1); } } } That code worked fine as long as the outgoing COM port operated at a higher baud rate than the incoming COM port. If the incoming COM port was faster than the outgoing COM port, I started missing data. I had to correct the code like this: private void HandleDataReceived(SerialPort inPort, SerialPort outPort) { byte[] data = new byte[1]; while (inPort.BytesToRead > 0) { // Read the data data[0] = (byte)inPort.ReadByte(); // Write the data if (outPort.IsOpen) { outPort.Write(data, 0, 1); while (outPort.BytesToWrite > 0); //<-- Change to fix problem } } } I don't understand why I need that fix. I'm new to C# (this is my first program), so I'm wondering if there is something I am missing. The SerialPort defaults to a 2048 byte write buffer and my commands are less than ten bytes. The write buffer should have the ability to buffer the data until it can be written to a slower COM port. In summary, I'm receiving data on COM X and writing the data to COM Y. COM X is connected at a faster baud rate than COM Y. Why doesn't the buffering in the write buffer handle this difference? Why does it seem that I need to wait for the write buffer to drain to avoid losing data? Thanks!

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• Jason/ajax web service call get redirected (302 Object moved) and then 500 unknow webservice name

  - by user646499

  I have been struggling with this for some times.. I searched around but didnt get a solution yet. This is only an issue on production server. In my development environment, everything works just fine. I am using JQuery/Ajax to update product information based on product's Color attribute. for example, a product has A and B color, the price for color A is different from color B. When user choose different color, the price information is updated as well. What I did is to first add a javascript function: function updateProductVariant() { var myval = jQuery("#<%=colorDropDownList.ClientID%").val(); jQuery.ajax({ type: "POST", url: "/Products.aspx/GetVariantInfoById", data: "{variantId:'" + myval + "'}", contentType: "application/json; charset=utf-8", dataType: "json", success: function (response) { var obj = jQuery.parseJSON(response.d); jQuery("#<%=lblStockAvailablity.ClientID%>").text(obj.StockMessage); jQuery(".price .productPrice").text(obj.CurrentPrice); jQuery(".price .oldProductPrice").text(obj.OldPrice); } }); } Then I can register the dropdown list's 'onclick' event point to function 'updateProductVariant' GetVariantInfoById is a WebGet method in the codebehind, its also very straightforward: [WebMethod] public static string GetVariantInfoById(string variantId) { int id = Convert.ToInt32(variantId); ProductVariant productVariant = IoC.Resolve().GetProductVariantById(id); string stockMessage = productVariant.FormatStockMessage(); StringBuilder oBuilder = new StringBuilder(); oBuilder.Append("{"); oBuilder.AppendFormat(@"""{0}"":""{1}"",", "StockMessage", stockMessage); oBuilder.AppendFormat(@"""{0}"":""{1}"",", "OldPrice", PriceHelper.FormatPrice(productVariant.OldPrice)); oBuilder.AppendFormat(@"""{0}"":""{1}""", "CurrentPrice", PriceHelper.FormatPrice(productVariant.Price)); oBuilder.Append("}"); return oBuilder.ToString(); } All these works fine on my local box, but if i upload to the production server, catching the traffic using fiddler, /Products.aspx/GetVariantInfoById becomes a Get call instead of a POST On my local box, HTTP/1.1 200 OK Server: ASP.NET Development Server/10.0.0.0 Date: Thu, 03 Mar 2011 09:00:08 GMT X-AspNet-Version: 4.0.30319 Cache-Control: private, max-age=0 Content-Type: application/json; charset=utf-8 Content-Length: 117 Connection: Close But when deployed on the host, it becomes HTTP/1.1 302 Found Proxy-Connection: Keep-Alive Connection: Keep-Alive Content-Length: 186 Via: 1.1 ADV-TMG-01 Date: Thu, 03 Mar 2011 08:59:12 GMT Location: http://www.pocomaru.com/Products.aspx/GetVariantInfoById/default.aspx Server: Microsoft-IIS/7.0 X-Powered-By: ASP.NET then of course, then it returns 500 error titleUnknown web method GetVariantInfoById/default.aspx.Parameter name: methodName Can someone please take a look? I think its some configuration in the production server which automatially redirects my webservice call to some other URL, but since the product server is out of my control, i am seeking a local fix for this. Thanks for the help!

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• LSP packet modify

  - by kellogs

  Hello, anybody care to share some insights on how to use LSP for packet modifying ? I am using the non IFS subtype and I can see how (pseudo?) packets first enter WSPRecv. But how do I modify them ? My inquiry is about one single HTTP response that causes WSPRecv to be called 3 times :((. I need to modify several parts of this response, but since it comes in 3 slices, it is pretty hard to modify it accordingly. And, maybe on other machines or under different conditions (such as high traffic) there would only be one sole WSPRecv call, or maybe 10 calls. What is the best way to work arround this (please no NDIS :D), and how to properly change the buffer (lpBuffers-buf) by increasing it ? int WSPAPI WSPRecv( SOCKET s, LPWSABUF lpBuffers, DWORD dwBufferCount, LPDWORD lpNumberOfBytesRecvd, LPDWORD lpFlags, LPWSAOVERLAPPED lpOverlapped, LPWSAOVERLAPPED_COMPLETION_ROUTINE lpCompletionRoutine, LPWSATHREADID lpThreadId, LPINT lpErrno ) { LPWSAOVERLAPPEDPLUS ProviderOverlapped = NULL; SOCK_INFO *SocketContext = NULL; int ret = SOCKET_ERROR; *lpErrno = NO_ERROR; // // Find our provider socket corresponding to this one // SocketContext = FindAndRefSocketContext(s, lpErrno); if ( NULL == SocketContext ) { dbgprint( "WSPRecv: FindAndRefSocketContext failed!" ); goto cleanup; } // // Check for overlapped I/O // if ( NULL != lpOverlapped ) { /*bla bla .. not interesting in my case*/ } else { ASSERT( SocketContext->Provider->NextProcTable.lpWSPRecv ); SetBlockingProvider(SocketContext->Provider); ret = SocketContext->Provider->NextProcTable.lpWSPRecv( SocketContext->ProviderSocket, lpBuffers, dwBufferCount, lpNumberOfBytesRecvd, lpFlags, lpOverlapped, lpCompletionRoutine, lpThreadId, lpErrno); SetBlockingProvider(NULL); //is this the place to modify packet length and contents ? if (strstr(lpBuffers->buf, "var mapObj = null;")) { int nLen = strlen(lpBuffers->buf) + 200; /*CHAR *szNewBuf = new CHAR[]; CHAR *pIndex; pIndex = strstr(lpBuffers->buf, "var mapObj = null;"); nLen = strlen(strncpy(szNewBuf, lpBuffers->buf, (pIndex - lpBuffers->buf) * sizeof (CHAR))); nLen = strlen(strncpy(szNewBuf + nLen * sizeof(CHAR), "var com = null;\r\n", 17 * sizeof(CHAR))); pIndex += 18 * sizeof(CHAR); nLen = strlen(strncpy(szNewBuf + nLen * sizeof(CHAR), pIndex, 1330 * sizeof (CHAR))); nLen = strlen(strncpy(szNewBuf + nLen * sizeof(CHAR), "if (com == null)\r\n" \ "com = new ActiveXObject(\"InterCommJS.Gateway\");\r\n" \ "com.lat = latitude;\r\n" \ "com.lon = longitude;\r\n}", 111 * sizeof (CHAR))); pIndex = strstr(szNewBuf, "Content-Length:"); pIndex += 16 * sizeof(CHAR); strncpy(pIndex, "1465", 4 * sizeof(CHAR)); lpBuffers->buf = szNewBuf; lpBuffers->len += 128;*/ } if ( SOCKET_ERROR != ret ) { SocketContext->BytesRecv += *lpNumberOfBytesRecvd; } } cleanup: if ( NULL != SocketContext ) DerefSocketContext( SocketContext, lpErrno ); return ret; } Thank you

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• Suggestions for designing large-scale Java webapp from the group up

  - by Chris Thompson

  Hi all, I'm about to start developing a large-scale system and I'm struggling with which direction to proceed. I've done plenty of Java web apps before and I have plenty of experience with servlet containers and GWT and some experience with Spring. The problem is most of my webapps have been thrown together just to be a proof of concept and what I'm struggling with is what set of frameworks to use. I need to have both a browser based application as well as a web service designed to support access from mobile devices (Android and iPhone for now). Ideally, I'd like to design this system in such a way that I don't end up rewriting all of my servlets for each client (browser and phone) although I don't mind having some small checks in there to properly format the data. In addition, although I'm the only developer now, that won't necessarily be the case down the road and I'd like to design something that scales well both with regards to traffic and number of developers (isn't just a nightmare to maintain). So where I am now is planning on using GWT to design the browser-based interface but I'm struggling with how to reuse that code with to present the interface (most likely xml) for the mobile devices. Using GWT RPC would, I think, make it relatively easy to do all of the AJAX in the browser, but might make generating xml for the mobile phones difficult. In addition, I like the idea of using something like Hibernate for persistence and Spring Security to secure the whole thing. Again, I'm not sure how well those will cooperate with GWT (I think Hibernate should be fine...) There's obviously a lot more to this than I've presented here, but I've tried to give you the 5-minute overview. I'm a bit stumped and was wondering if anybody in the community had any experience starting from this place. Does what I'm trying to do make sense? Is it realistic? I have no doubt I can make all of these frameworks speak the same language, I'm just wondering if it's worth my time to fight with them. Also, am I missing a framework that would be really beneficial? Thanks in advance and sorry for the relatively broad question... Chris

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• Implement Semi-Round-Robin file which can be expanded and saved on demand

  - by ircmaxell

  Ok, that title is going to be a little bit confusing. Let me try to explain it a little bit better. I am building a logging program. The program will have 3 main states: Write to a round-robin buffer file, keeping only the last 10 minutes of data. Write to a buffer file, ignoring the time (record all data). Rename entire buffer file, and start a new one with the past 10 minutes of data (and change state to 1). Now, the use case is this. I have been experiencing some network bottlenecks from time to time in our network. So I want to build a system to record TCP traffic when it detects the bottleneck (detection via Nagios). However by the time it detects the bottlenecking, most of the useful data has already been transmitted. So, what I'd like is to have a deamon that runs something like dumpcap all the time. In normal mode, it'll only keep the past 10 minutes of data (Since there's no point in keeping a boat load of data if it's not needed). But when Nagios alerts, I will send a signal in the deamon to store everything. Then, when Naigos recovers it will send another signal to stop storing and flush the buffer to a save file. Now, the problem is that I can't see how to cleanly store a rotating 10 minutes of data. I could store a new file every 10 minutes and delete the old ones if in mode 1. But that seems a bit dirty to me (especially when it comes to figuring out when the alert happened in the file). Ideally, the file that was saved should be such that the alert is always at the 10:00 mark in the file. While that is possible with new files every 10 minutes, it seems like a bit dirty to "repair" the files to that point. Any ideas? Should I just do a rotating file system and combine them into 1 at the end (doing quite a bit of post-processing)? Is there a way to implement the semi-round-robin file cleanly so that there is no need for any post-processing? Thanks Oh, and the language doesn't matter as much at this stage (I'm leaning towards Python, but have no objection to any other language. It's less of an issue than the overall design)...

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• Servlet IOException when streaming a Byte Array

  - by MontyBongo

  I occasionally get an IOException from a Servlet I have that writes a byte array to the outputstream in order to provide a file download capability. This download servlet has a reasonable amount of traffic (100k hits a month) and this exception occurs rarely, around 1-2 times a month. I have tried recreating the exception by using the exact same Base64 String and no exception is raised and the Servlet behaves as designed. Is this IO Exception being caused by something outside my applications control? For example a network issue or the user resetting the connection? I have tried to google the cause of an IOException at this point in the stack but to no avail. The environment is running Tomcat 5.5 on CentOS 5.3 with an Apache HTTP Server acting as a proxy using proxy_ajp. ClientAbortException: java.io.IOException at org.apache.catalina.connector.OutputBuffer.realWriteBytes(OutputBufferjava:366) at org.apache.tomcat.util.buf.ByteChunk.append(ByteChunk.java:352) at org.apache.catalina.connector.OutputBuffer.writeBytes(OutputBuffer.java:392) at org.apache.catalina.connector.OutputBuffer.write(OutputBuffer.java:381) at org.apache.catalina.connector.CoyoteOutputStream.write(CoyoteOutputStream.java:89) at org.apache.catalina.connector.CoyoteOutputStream.write(CoyoteOutputStream.java:83) at com.myApp.Download.doPost(Download.java:34) at javax.servlet.http.HttpServlet.service(HttpServlet.java:710) at javax.servlet.http.HttpServlet.service(HttpServlet.java:803) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:269) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:188) at org.apache.catalina.core.ApplicationDispatcher.invoke(ApplicationDispatcher.java:691) at org.apache.catalina.core.ApplicationDispatcher.processRequest(ApplicationDispatcher.java:469) at org.apache.catalina.core.ApplicationDispatcher.doForward(ApplicationDispatcher.java:403) at org.apache.catalina.core.ApplicationDispatcher.forward(ApplicationDispatcher.java:301) at com.myApp.EntryServlet.service(EntryServlet.java:278) at javax.servlet.http.HttpServlet.service(HttpServlet.java:803) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:269) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:188) at com.myApp.filters.RequestFilter.doFilter(RequestFilter.java:16) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:215) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:188) at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:210) at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:172) at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127) at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:117) at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:108) at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:151) at org.apache.coyote.ajp.AjpAprProcessor.process(AjpAprProcessor.java:444) at org.apache.coyote.ajp.AjpAprProtocol$AjpConnectionHandler.process(AjpAprProtocol.java:472) at org.apache.tomcat.util.net.AprEndpoint$Worker.run(AprEndpoint.java:1286) at java.lang.Thread.run(Thread.java:636) Caused by: java.io.IOException at org.apache.coyote.ajp.AjpAprProcessor.flush(AjpAprProcessor.java:1200) at org.apache.coyote.ajp.AjpAprProcessor$SocketOutputBuffer.doWrite(AjpAprProcessor.java:1285) at org.apache.coyote.Response.doWrite(Response.java:560) at org.apache.catalina.connector.OutputBuffer.realWriteBytes(OutputBufferjava:361) And the code in the Download Servlet: @Override protected void doPost (HttpServletRequest request, HttpServletResponse response) throws ServletException, java.io.IOException { try { response.setContentType("application/pdf"); response.setHeader("Pragma", ""); response.setHeader("Cache-Control", ""); response.setHeader("Content-Disposition", "Inline; Filename=myPDFFile..pdf"); ServletOutputStream out = response.getOutputStream(); byte[] downloadBytes = Base64.decode((String)request.getAttribute("fileToDownloadBase64")); out.write(downloadBytes); } catch (Base64DecodingException e) { e.printStackTrace(); response.getOutputStream().print("An error occurred"); } }

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• Dealing with missing messages in JavaScript when using BOSH

  - by JamieD

  We recently went into private beta on our flagship product and had a small launch event. Unfortunately the venue had a terrible wireless connection and packets were being dropped left right and centre causing havoc with out system, basically it wasn't able to work at all! Luckily we were able to switch to a different network and rescue the demo. This highlighted something that I knew was already an issue but hadn't appreciated quite how much of an issue it could be. Our system relies heavily on BOSH and has a rather large JavaScript code base which now works rather well under good network conditions. However we need to make it work well under bad network conditions as well. Due to the way that XMPP works, a fire and forget system, it's not easy to tell if a message you sent, or were supposed to receive, was actually sent or received. For instance, we have an offer system, one user will send an offer to another over BOSH. When this message is received by the server a message is published to the offering users offers_sent PEP node and a similar message to the receiving users offers_received PEP node. While the sending user is able to tell if their offer was send (relatively) easily, if the notification to the receiving user is never received that user will never know it missed a message. A little about out JavaScript setup, it has 4 main layers: StropheJS An MVC framework for dealing with low level tasks and to build on top of An application layer which contains the app logic routes, controllers models etc. as well as a browser cache of the model data A UI layer that receives events and publishes events to and from the application layer One way to solve the missing messages issue would be to periodically check the PEP nodes for new data that the browser doesn't know about. If a new message was discovered the browsers cache would be invalidated and all new data would be requested from the server. I'm not sure this is the best way to go and it also doesn't cover all situations. We certainly don't want to get into the situation where we are sending messages to confirm the previous message was received at it's destination as this would double the network traffic. With the number of real time websites growing daily this is an issue that must have been encountered by other developers, it would be interesting to see how it's been solved by others. As far as I can see there are two situations in which messages go missing: On poor connections messages are not sent or received due to the packets being dropped Involving navigating between pages, a message is received by the browser but is not fully processed and stored in the local cache before the page is unloaded. Or a message is added to the send queue but never sent before the page is unloaded I suspect the hardest issue to solve will be number 2. Any thoughts on the subject would be much appreciated.

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• Suggestions for designing large-scale Java webapp from the ground up

  - by Chris Thompson

  Hi all, I'm about to start developing a large-scale system and I'm struggling with which direction to proceed. I've done plenty of Java web apps before and I have plenty of experience with servlet containers and GWT and some experience with Spring. The problem is most of my webapps have been thrown together just to be a proof of concept and what I'm struggling with is what set of frameworks to use. I need to have both a browser based application as well as a web service designed to support access from mobile devices (Android and iPhone for now). Ideally, I'd like to design this system in such a way that I don't end up rewriting all of my servlets for each client (browser and phone) although I don't mind having some small checks in there to properly format the data. In addition, although I'm the only developer now, that won't necessarily be the case down the road and I'd like to design something that scales well both with regards to traffic and number of developers (isn't just a nightmare to maintain). So where I am now is planning on using GWT to design the browser-based interface but I'm struggling with how to reuse that code with to present the interface (most likely xml) for the mobile devices. Using GWT RPC would, I think, make it relatively easy to do all of the AJAX in the browser, but might make generating xml for the mobile phones difficult. In addition, I like the idea of using something like Hibernate for persistence and Spring Security to secure the whole thing. Again, I'm not sure how well those will cooperate with GWT (I think Hibernate should be fine...) There's obviously a lot more to this than I've presented here, but I've tried to give you the 5-minute overview. I'm a bit stumped and was wondering if anybody in the community had any experience starting from this place. Does what I'm trying to do make sense? Is it realistic? I have no doubt I can make all of these frameworks speak the same language, I'm just wondering if it's worth my time to fight with them. Also, am I missing a framework that would be really beneficial? Thanks in advance and sorry for the relatively broad question... Chris

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• An IOCP documentation interpretation question - buffer ownership ambiguity

  - by Poni

  Since I'm not a native English speaker I might be missing something so maybe someone here knows better than me. Taken from WSASend's doumentation at MSDN: lpBuffers [in] A pointer to an array of WSABUF structures. Each WSABUF structure contains a pointer to a buffer and the length, in bytes, of the buffer. For a Winsock application, once the WSASend function is called, the system owns these buffers and the application may not access them. This array must remain valid for the duration of the send operation. Ok, can you see the bold text? That's the unclear spot! I can think of two translations for this line (might be something else, you name it): Translation 1 - "buffers" refers to the OVERLAPPED structure that I pass this function when calling it. I may reuse the object again only when getting a completion notification about it. Translation 2 - "buffers" refer to the actual buffers, those with the data I'm sending. If the WSABUF object points to one buffer, then I cannot touch this buffer until the operation is complete. Can anyone tell what's the right interpretation to that line? And..... If the answer is the second one - how would you resolve it? Because to me it implies that for each and every data/buffer I'm sending I must retain a copy of it at the sender side - thus having MANY "pending" buffers (in different sizes) on an high traffic application, which really going to hurt "scalability". Statement 1: In addition to the above paragraph (the "And...."), I thought that IOCP copies the data to-be-sent to it's own buffer and sends from there, unless you set SO_SNDBUF to zero. Statement 2: I use stack-allocated buffers (you know, something like char cBuff[1024]; at the function body - if the translation to the main question is the second option (i.e buffers must stay as they are until the send is complete), then... that really screws things up big-time! Can you think of a way to resolve it? (I know, I asked it in other words above).

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• What are the benefits of using ORM over XML Serialization/Deserialization?

  - by Tequila Jinx

  I've been reading about NHibernate and Microsoft's Entity Framework to perform Object Relational Mapping against my data access layer. I'm interested in the benefits of having an established framework to perform ORM, but I'm curious as to the performance costs of using it against standard XML Serialization and Deserialization. Right now, I develop stored procedures in Oracle and SQL Server that use XML Types for either input or output parameters and return or shred XML depending on need. I use a custom database command object that uses generics to deserialize the XML results into a specified serializable class. By using a combination of generics, xml (de)serialization and Microsoft's DAAB, I've got a process that's fairly simple to develop against regardless of the data source. Moreover, since I exclusively use Stored Procedures to perform database operations, I'm mostly protected from changes in the data structure. Here's an over-simplified example of what I've been doing. static void main() { testXmlClass test = new test(1); test.Name = "Foo"; test.Save(); } // Example Serializable Class ------------------------------------------------ [XmlRootAttribute("test")] class testXmlClass() { [XmlElement(Name="id")] public int ID {set; get;} [XmlElement(Name="name")] public string Name {set; get;} //create an instance of the class loaded with data. public testXmlClass(int id) { GenericDBProvider db = new GenericDBProvider(); this = db.ExecuteSerializable("myGetByIDProcedure"); } //save the class to the database... public Save() { GenericDBProvider db = new GenericDBProvider(); db.AddInParameter("myInputParameter", DbType.XML, this); db.ExecuteSerializableNonQuery("mySaveProcedure"); } } // Database Handler ---------------------------------------------------------- class GenericDBProvider { public T ExecuteSerializable<T>(string commandText) where T : class { XmlSerializer xml = new XmlSerializer(typeof(T)); // connection and command code is assumed for the purposes of this example. // the final results basically just come down to... return xml.Deserialize(commandResults) as T; } public void ExecuteSerializableNonQuery(string commandText) { // once again, connection and command code is assumed... // basically, just execute the command along with the specified // parameters which have been serialized. } public void AddInParameter(string name, DbType type, object value) { StringWriter w = new StringWriter(); XmlSerializer x = new XmlSerializer(value.GetType()); //handle serialization for serializable classes. if (type == DbType.Xml && (value.GetType() != typeof(System.String))) { x.Serialize(w, value); w.Close(); // store serialized object in a DbParameterCollection accessible // to my other methods. } else { //handle all other parameter types } } } I'm starting a new project which will rely heavily on database operations. I'm very curious to know whether my current practices will be sustainable in a high-traffic situation and whether or not I should consider switching to NHibernate or Microsoft's Entity Framework to perform what essentially seems to boil down to the same thing I'm currently doing. I appreciate any advice you may have.

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• Sanity check on this idea for an Image Viewer in a web app

  - by Charlie Flowers

  I have an approach in mind for an image viewer in a web app, and want to get a sanity check and any thoughts you stackoverflowers might have. Here's the whirlwind nutshell summary: I'm working on an ASP.NET MVC application that will run in my company's retail stores. Even though it is a web application, we own the store machines and have control over them. We have a "windows agent" running on the store machine which we can talk to via http post (it is a WCF service, and our web app has permission to talk to it from the browser). One of the web pages needs to be an "image viewer" page with some common things like Rotate & Zoom. Now, there are some WebForms controls that offer Rotate and Zoom. However, they take up server resources and generate a good bit of traffic between the server and the browser. For example, the Rotate function would cause an ajax call to the server, which would then generate a new image written to a .NET Canvas object, which would then be written to a file on the server, which would then be returned from the ajax call and refreshed inside the browser. Normally, that's a pretty good way of doing things. But in our case, we have code running on the store machine that we can communicate with. This leads me to consider the following approach: When the user asks to view an image, we tell our "windows agent" to download it from our image server to the store machine. We then redirect our browser to our image viewer page, which will pull the image from the local file we just wrote to the store machine. When the user clicks "Rotate", we cause JavaScript code in the browser to call our "windows agent" software, asking it to perform the "Rotate" function. The "windows agent" does the rotation using the same kind of imaging control that would formerly have been used on the server, but it does so now on the store machine. Javascript in the browser then refreshes the image on the page to show the newly rotated image. Zoom and similar features would be implemented the same way. This seems to be much more efficient, scalable, and responsive for the end-users. However, I've never heard of anything like it being done, mostly because it's rare to have this combination of a web app plus a "windows agent" on the client machine. What do you think? Feasible? Reasonable? Any pitfalls I overlooked or improvements / suggestions you can see? Has anyone done anything like this who would like to offer the wisdom of experience? Thanks!

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• Container item implementation

  - by onurozcelik

  Hi, I am working in Train Traffic Controller software project. My responsibility in this project is to develop the visual railroad GUI. We are implementing the project with Qt. By now I am using QGraphicsLinearLayout to hold my items. I am using the layout because I do not want to calculate coordinates of each item. So far I wrote item classes to add the layout. For instance SwitchItem class symbolizes railroad switch in real world. Each item class is responsible for its own painting and events. So far so good. Now I need a composite item that can contain two or more item. This class is going to be responsible for painting the items contained in it. I need this class because I have to put two or more items inside same layout cell. If I don' t put them in same cell I can' t use layout. See the image below. BlockSegmentItem and SignalItem inside same cell. Here is my compositeitem implementation. #include "compositeitem.h" CompositeItem::CompositeItem(QString id,QList<FieldItem *> _children) { children = _children; } CompositeItem::~CompositeItem() { } QRectF CompositeItem::boundingRect() const { FieldItem *child; QRectF rect(0,0,0,0); foreach(child,children) { rect = rect.united(child->boundingRect()); } return rect; } void CompositeItem::paint(QPainter *painter, const QStyleOptionGraphicsItem *option, QWidget *widget ) { FieldItem *child; foreach(child,children) { child->paint(painter,option,widget); } } QSizeF CompositeItem::sizeHint(Qt::SizeHint which, const QSizeF &constraint) const { QSizeF itsSize(0,0); FieldItem *child; foreach(child,children) { // if its size empty set first child size to itsSize if(itsSize.isEmpty()) itsSize = child->sizeHint(Qt::PreferredSize); else { QSizeF childSize = child->sizeHint(Qt::PreferredSize); if(itsSize.width() < childSize.width()) itsSize.setWidth(childSize.width()); itsSize.setHeight(itsSize.height() + childSize.height()); } } return itsSize; } void CompositeItem::contextMenuEvent(QGraphicsSceneContextMenuEvent *event) { qDebug()<<"Test"; } This code works good with painting but when it comes to item events it is problematic. QGraphicsScene treats the composite item like a single item which is right for layout but not for events. Because each item has its own event implementation.(e.g. SignalItem has its special context menu event.) I have to handle item events seperately. Also I need a composite item implementation for the layout. How can I overcome this dilemma?

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• What is the best way to read and write cXML documents in C# ?

  - by tetranz

  I know this is a vague open ended question. I'm hoping to get some general direction. I need to add cXML punchout to an ASP.NET C# site / application. This is replacing something that I wrote years ago in ColdFusion. I'm a reasonably experienced C# developer but I haven't done much with XML. There seems to be lots of different options for processing XML in .NET. Here's the open ended question: Assuming that I have an XML document in some form, eg a file or a string, what is the best way to read it into my code? I want to get the data and then query databases etc. The cXML document size and our traffic volumes are easily small enough so that loading the a cXML document into memory is not a problem. Should I: 1) Manually build classes based on the dtd and use the XML Serializer? 2) Use a tool to generate classes. There are sample cXML files downloadable from Ariba.com. I tried xsd.exe to generate an xsd and then xsd.exe /c to generate classes. When I try to deserialize I get errors because there seems to be "confusion" around whether some elements should be single values or arrays. I tried the CodeXS online tool but that gives errors in it's log and errors if I try to deserialize a sample document. 2) Create a dataset and ReadXml()? 3) Create a typed dataset and ReadXml()? 4) Use Linq to XML. I often use Linq to Objects so I'm familiar with Linq in general but I'm struggling to see what it gives me in this situation. 5) Some other means. I guess I need to improve my understanding of XML in general but even so ... am I missing some obvious way of doing this? In the old ColdFusion site I found a free component ("tag") which basically ignored any schema and read the XML into a "structure" which is essentially a series of nested hash tables which was then easy to read in code. That was probably quite sloppy but it worked. I also need to generate XML files from my C# objects. Maybe Linq to XML will be good for that. I could start with a default "template" document and manipulate it before saving. Thanks for any pointers ...

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• jboss connection pooling

  - by Web

  I have a question related to Prepared Steatement pooling (across all connections). Here's the config file <datasources> <local-tx-datasource> <jndi-name>JNDI-NAME</jndi-name> <connection-url>jdbc:mysql://<server_name>/<database_name>?useServerPrepStmts=true</connection-url> <driver-class>com.mysql.jdbc.Driver</driver-class> <user-name>xxx</user-name> <password>xxxxx</password> <min-pool-size>10</min-pool-size> <max-pool-size>20</max-pool-size> <idle-timeout-minutes>20</idle-timeout-minutes> <exception-sorter-class-name>org.jboss.resource.adapter.jdbc.vendor.MySQLExceptionSorter</exception-sorter-class-name> <valid-connection-checker-class-name>org.jboss.resource.adapter.jdbc.vendor.MySQLValidConnectionChecker</valid-connection-checker-class-name> <background-validation>true</background-validation> <background-validation-minutes>5</background-validation-minutes> <prepared-statement-cache-size>100</prepared-statement-cache-size> <share-prepared-statements>true</share-prepared-statements> <!-- sql to call when connection is created <new-connection-sql>some arbitrary sql</new-connection-sql> --> <!-- sql to call on an existing pooled connection when it is obtained from pool - MySQLValidConnectionChecker is preferred for newer drivers <check-valid-connection-sql>some arbitrary sql</check-valid-connection-sql> --> <!-- corresponding type-mapping in the standardjbosscmp-jdbc.xml --> <metadata> <type-mapping>mySQL</type-mapping> </metadata> </local-tx-datasource> </datasources> It seems that this line: <background-validation-minutes>5</background-validation-minutes> doesn't cause any problems with Prepared Statements, but: <idle-timeout-minutes>20</idle-timeout-minutes> causes that all connections are removed and re-created if there was no traffic for the last 20 minutes. Because of that existing Prepared Statements are removed from the pool of cached Prepared Statements. How to overcome this issue? I have to use idle-timeout-minutes because MySQL server closes the connection after 8h

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• The best way to separate admin functionality from a public site?

  - by AndrewO

  I'm working on a site that's grown both in terms of user-base and functionality to the point where it's becoming evident that some of the admin tasks should be separate from the public website. I was wondering what the best way to do this would be. For example, the site has a large social component to it, and a public sales interface. But at the same time, there's back office tasks, bulk upload processing, dashboards (with long running queries), and customer relations tools in the admin section that I would like to not be effected by spikes in public traffic (or effect the public-facing response time). The site is running on a fairly standard Rails/MySQL/Linux stack, but I think this is more of an architecture problem than an implementation one: mainly, how does one keep the data and business logic in sync between these different applications? Some strategies that I'm evaluating: 1) Create a slave database of the public facing database on another machine. Extract out all of the model and library code so that it can be shared between the applications. Create new controllers and views for the admin interfaces. I have limited experience with replication and am not even sure that it's supposed to be used this way (most of the time I've seen it, it's been for scaling out the read capabilities of the same application, rather than having multiple different ones). I'm also worried about the potential for latency issues if the slave is not on the same network. 2) Create new more task/department-specific applications and use a message oriented middleware to integrate them. I read Enterprise Integration Patterns awhile back and they seemed to advocate this for distributed systems. (Alternatively, in some cases the basic Rails-style RESTful API functionality might suffice.) But, I have nightmares about data synchronization issues and the massive re-architecting that this would entail. 3) Some mixture of the two. For example, the only public information necessary for some of the back office tasks is a read-only completion time or status. Would it make sense to have that on a completely separate system and send the data to public? Meanwhile, the user/group admin functionality would be run on a separate system sharing the database? The downside is, this seems to keep many of the concerns I have with the first two, especially the re-architecting. I'm sure the answers are going to be highly dependent on a site's specific needs, but I'd love to hear success (or failure) stories.

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