This article will introduce the basic concepts of JGroups and then implement a task distribution system (on top of JGroups), where tasks can be placed into the cluster and are executed by worker nodes. It'll show that worker nodes can be added at run time to add more processing power, or taken down when we don't have much load. Plus, tasks assigned to workers who subsequently crash are automatically reassigned to live nodes.
Most NIO frameworks can saturate 1 gigabit ethernet at some point. However, some frameworks can saturate the bandwidth with the smaller number of connections while others can not. The performance numbers of the 5 well-known open source NIO frameworks are presented here to help you figure out the excellence of Netty in performance.
Gearman is an open source message queuing system that makes it easy to do distributed job processing using multiple languages. With Gearman you: farm out work to other machines, dispatching function calls to machines that are better suited to do work, to do work in parallel, to load balance lots of function calls, to call functions between languages, spread CPU usage around your network.
http://www.adamsinfo.com/dns-hijacking-isp-packet-modification-morals-and-privacy/#more-118
While looking at some data statistics for one of our racks, I noticed that the DNS service has become incredibly busy as of late. Now about 4 years ago when these particular name servers were set up, they were left with their default option to respond to DNS queries to anyone for anyone. It’s not really terrible but hardly ideal so I began changing some settings. I do notice though that we seem to now be providing name server access to the large majority of the world. Only recently did I read an article on DNS Hijacking that certain ISPs use to deliver pay per click ads to their subscribers when they do anything from first start their browser to each time they hit a DNS error.
Now personally I think it’s a pretty cheap thing to do, and it’s also quite frustrating to those users that have to suffer this ‘feature’. A number of ISPs use such methods to ‘improve’ the quality of your service and I think it’s all pretty bad. I don’t think there’s anything wrong with legitimate website ads in order to earn an author or site master some money – I’m going to put a few here sometime, however offensive advert popups or other nasty behavior are really not acceptable by anyones standards anymore.
Hijacking DNS queries, sniffing and modifying HTTP in any way, sniffing or modifying any kind of email or email failure, redirecting IPs, transparently proxying web traffic, analyzing your traffic, shaping your torrent-like or other rule matched traffic, etc, etc – you get the idea, are some of the more popular techniques out there. In worst cases an ISP would even firewall your inbound and outbound port access.
Bottom line, it’s not right. In a reasonable ‘open source’ mentality, an ISP should offer a clean, usable connection. They should not affect or modify your traffic in any way, seek to gain advertising from it or anything similar. If you mess about with end users connections, users usually end up complaining to site providers about something that isn’t their problem, and don’t get to understand what they’re doing and how or why their internet behaves differently to the next guy’s.
With that, I was confident that injecting ads for profit or otherwise messing about with my now-popular DNS service wasn’t a good thing to do, even if my subscribers shouldn’t have been subscribers :mrgreen: . I restricted access to the relevant ranges, and with that I was done.
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User:davidapnic
Someone in the forums recently asked about ways to migrate individual accounts from one ZCS instance to another, so thought I’d share the enlightenment with all. Whether you are going from an on-premise install to a hosting provider, want to create handy archives of old employee accounts, or just need to duplicate mailbox contents of a user; the syntax in this article proves remarkably useful, and applies to all editions.

There are a multitude of comparable RFE’s on addressing this need via different approaches. (Bugzilla entries 19630, 29573, 28443 & 30163 to name a few.) Some want graphical tools to browse data and selectively migrate certain things, while others would be happy with a cross LDAP zmmailboxmove.
Depending on your situation, several backup tools can take care of a large portion of your daily needs; and there are ways to do Zimbra-to-Zimbra migrations using the Network Edition’s backup and restore capabilities - however they require admin abilities on both systems. Meanwhile, most of the frequently used open source backup solutions are simply an “all accounts at-once” approach. So what to do when you need to move from your personal setup to a hosting provider? Or if you’re a hosting provider, move a tiny handful of accounts to a separate infrastructure? Before diving into the wiki on user migration for info on Imapsync, REST exports, CURL imports, etc; there’s a handy way to avoid the “one item type at-a-time” transfer methods.
In ZCS 5.0.9+ you can export an entire mailbox with:
/opt/zimbra/bin/zmmailbox -z -m user@domain.com getRestURL “//?fmt=tgz” > /tmp/account.tgz
Next transfer via rsync, scp, sftp, etc. You’ll also need to create the account on the 2nd server if the desired account doesn’t exist at your destination server yet.
Then import with:
/opt/zimbra/bin/zmmailbox -z -m user@domain.com postRestURL “//?fmt=tgz&resolve=reset” /tmp/account.tgz
The resolve= paramater has several options:
‘Reset’ will be a bit faster on an empty destination mailbox because it skips most dupe checks.
Note: There were some duplication fixes and additional issues (mainly sync related) corrected with the tar formatter in 5.0.10.
Not a Zimbra Admin? Users can get the same zip/tar formatter on REST URL’s by visiting:
http:// server.domain.com/home/user?fmt=zip&query=is:anywhere
The zip format has been around for a long time, but doesn’t contain account & item metadata like the tar formatter automatically does:
http:// server.domain.com/home/user/?fmt=tgz
Infact, this same technique is currently used in Zimbra Desktop’s alpha backup solution.
If this approach doesn’t scale performance wise for your situation, or you simply don’t want to have everyone hit a REST URL for 30GB mailboxes all at the same time, here’s a collection of helpful scripts and other ways to systematically migrate:
Mysqldump & rsync with an interesting blob management technique: Zimbra2Zimbra
Imapsync for mail + postRestURL for contacts, calendar & filters: ZimbraMigrate (Expand the concept for tasks, documents, and briefcase items.)
Another method that could be extrapolated upon for migrations: Per User Mailbox Backup (OE Version - Zimbra :: Wiki)
Most of these solutions aren’t going to respect share permissions, but when pulling an account out of an environment that’s to be expected.
Zimlet spin-offs:
- Mail backup options for end users (.eml)
- Zimlet to save email in a txt file (.txt or html)
The above Zimlets are aimed at making quick self-copies & not for restores, but there are many methods for putting messages back into Zimbra, including tools like zmmailbox addMessge, zmlmtpinject, CURL, etc; for more info checkout these threads: Recover data from store folders & Moving Folders between users
If moving your entire server, I’m a huge fan of the install.sh -s trick when using NE backups to do so isn’t an option.
The position of president and chief operations officer has apparently been created and awarded to Rob Bearden, an entrepreneur in residence with Benchmark Capital. Bearden is former chief operations officer for JBoss, now owned by Red Hat.
The last couple of months, the development team at a small Norwegian company called Integrasco A/S have been working hard on designing a new, scalable database architecture and search system. As a temporary move while we are designing and implementing this new system, we have expanded our server park with a new server, and configured this in a master-slave fashion. Database replication is done through mysql bin-logs, but we faced a challenge when it came to the replication of our Lucene indexes. This is how we solved it:
Sometimes we need to access the HTTP request information within the business logic of your web service. With Axis2, is this trivial as Axis2 keeps the HttpServletRequest as a MessageContext property. We can easily get hold of that extract the necessary information out of it. Here is a simple web service which demonstrates how do it.
walkthrough in 20 slides to get OpenSolaris running smoothly under Windows host. thumb-up the effort !