Shared Sessions between WAS instances

[jthornton]

Hi. I have scoured the forum looking for the answer to my question but am not able to find it. First let me layout the facts of my situation to be. 1. We will have two or three servers running the WAS (for fail over/redundancy/load balance). 2. All WAS instances look at the same SQL database. 3. The application on all WAS systems is the same. My understanding is that the WAS would have separate instances and thus separate sessions. Therefore, a user would need to login into the second instance to gain access to the application being served on the second or third server even though it is the same app. Our goal is to load balance between the servers (e.g. round robin) so that a user in theory would have access to all servers (depending on load balance rotation to provide high availability, performance, and failover) without having to login multiple times. With that in mind, is there a way to share a login session between multiple server instances of the same application without requiring the user to manually login to each server during the rotation to establish a new session?

[Steve Wood]

Re: Shared Sessions between WAS instances

A load balancer balances users across multiple instances/IP's but each user has their own session once connected. You do need a separate IP for each instance. They could not "login" to the other server because it would not exist as far as their connection was concerned. That is, if they only have one URL, they only get one connection. If you had seperate URLs for each server, that might be different. The best thing to do is shoot an email to [email protected]. He has plenty of load balancer experience.

By the way, has anyone had a chance to test V11 WAS in terms of performance over V10?

[chadbrown]

Re: Shared Sessions between WAS instances

Steve it seems to be a bit slower but haven't played enough to give an accurate assessment.

[Peter.Greulich]

Re: Shared Sessions between WAS instances

Steve it seems to be a bit slower but haven't played enough to give an accurate assessment.

Someone else said that as well.

[chadbrown]

Re: Shared Sessions between WAS instances

My main tabbed ui is about 8seconds to load which on v10 is 4seconds on the same server. Most of it loads quick but the home tab seems to lag a bit. Everything else seems to be about the same as v10.

[Steve Wood]

Re: Shared Sessions between WAS instances

Jeremy,

Didn't mean to derail your post with my performance question.

The thing about Instances of Alpha Five app server is that each takes a separate IP address. I am not an IT guy, but I am pretty sure that this fact precludes one individual user spreading their load across multiple instance, let alone multiple servers. Even when it goes through the load balancer on a single IP, the side that connects to your Instances are still multiple IP addresses. IF it is possible for a load balancer to float sessions between IP addresses, then that might allow. I only had one experience, an 18 Instance on a 24 core single machine with a Load Balancer provided by Zebrahost. I don't have historical data because that client cut back to a single instance after a few months of no sales.

Another way to load balance is to just provide a different URL for each instance, and sort of manually divvy up those URLs between your users.

[jthornton]

Re: Shared Sessions between WAS instances

Thanks Steve. I have sent him an email. Our goal is to have something like "domain.com" pointing to a load balancer, which then based on a set of load balance rules would forward the user to server 10.10.10.1 or server 10.10.10.2. However, the login session started on the first login would need to be carried between servers as the load balance passed the traffic to the various ips. I am hoping that there is a way for the multiple WAS's to be able to share a session folder between servers (seems most efficient) or maybe something like a "cloud" shared folder holding the session info. If not, unless someone knows something I don't, I guess one would have to program manually in the application the url's that include various user information variables to be passed in the link for the servers to automatically log the user in as the traffic is passed to it. Nevertheless, I will await some help from Clive on the matter, but any additional feedback or ideas from the forum will also be appreciated on ways to share a session between server instances of the same app (without users "manually" logging into each server).

[chadbrown]

Re: Shared Sessions between WAS instances

If you use a bunch of servers you can still share a webroot from what I understand so all session folders would be in the same place the servers would all be mapped to the same webroot and away you go. But if that webroot is unavailable on any of the servers you are done.

[jthornton]

Re: Shared Sessions between WAS instances

No problem and I appreciate your help in directing me to Clive. I read the forums all the time and find that the various discussions that occur from a beginning question are often times just as helpful. I am just as interested in performance issues too! As for divvying up url's I have thought of that but I am trying to avoid it as much as possible so that the app can scale up or down on the server side without relocating users to different urls yet the change would be seamless to the users. As you know in your experience the less hassle and change for the users the better! Thanks.

[jthornton]

Re: Shared Sessions between WAS instances

If you use a bunch of servers you can still share a webroot from what I understand so all session folders would be in the same place the servers would all be mapped to the same webroot and away you go. But if that webroot is unavailable on any of the servers you are done.

I will certainly test this as an option when we are ready, but I would be afraid performance would be impacted in this case (specifically the benefits of load balance and fail over as well as serving speed of the instances since all have to go out to a shared folder) but if it works it would accomplish what I have in mind for shared sessions. Do you have any experience with this type of setup and performance experience?

[chadbrown]

Re: Shared Sessions between WAS instances

I dont use this myself but I do know a developer that does. If you go this route let me know and I can contact him and ask him to share some insight. I use dropbox to share files that are common on multiple servers but I would think that's not quick or trust it enough to use common files like session folders.

[jthornton]

Re: Shared Sessions between WAS instances

I dont use this myself but I do know a developer that does. If you go this route let me know and I can contact him and ask him to share some insight. I use dropbox to share files that are common on multiple servers but I would think that's not quick or trust it enough to use common files like session folders.

That was just what I was thinking (a DropBox like setup), but I am with you in production environments I do not know how reliable this would be.

[bea2701]

Re: Shared Sessions between WAS instances

I personally would not use dropbox in production leads to the loss of performance keep all session-folders within your infrastructure that is the safest way.
Much has been said and written about load balancing there is nothing better like a stress test and is the best available test remidie to find the truth it works or it does not.
Chad is correct a shared folder session on one machine shows the risk that if that machine goes down you have nothing.
I have no idea of the number of users and your availability to your system but to ensure I would choose as an example: 3-2-2.
Three of the WAS, two for file sharing (webroot) and two database servers. This is a costly business this way.
Alpha Software has announced support for IIS V11 that changed things . Contact these guys for more details.


Finally, there is much confusion about sessions and WAS servers. In order to conduct sessions across multiple application servers for this you need a broker who is not A5 instance.
See this a Master-Slave conductor example 2 Brokers and X WAS instances the broker is the watcher and sends the client to (xyz) was instance then the broker is the session handler not the WAS instance. The number of ip's is not important that could be one domain of more depending on your needs .

Hard versus software load balancing is a different behavior than the broker solution, but may be an alternative.
What I at least know that the introduction of the V11 IIS version will tell more details. We have to wait for the time Beta comes out

[The Mage]

Re: Shared Sessions between WAS instances

I have actually wondered about having a domain send people to a login page either on itself, or a sub-domain. This would be before any session information is stored, other then updating a table that records where the last user was sent. Need another instance, then add another sub-domain, and another instance.

[jthornton]

Re: Shared Sessions between WAS instances

Well after further reading it appears that it is possible to load balance (at least partially) at the moment using a load balancer that supports session affinity/sticky sessions. The balancer keeps the user on the same server they originally login. As more users enter the load balance moves down the list of servers setup. It acts more like a gateway that limits X number of users to a particular ip/port. This is good for controlling users per server and moving the load to the next server, but the problem occurs in that it is really not performance geared. As one could have a heavy load on server 1 while server 2 barely gets any of the work thus not using some resources to better the performance of the load. Nevertheless, at least there are some options to accomplish elements of load balance for users. At present the idea of a shared session folder and ip redirects between app servers seems the best option to accomplish a truer load balance, but testing of performance and reliability will be crucial. I have not heard from Clive yet, but I am hoping he will have some more ideas on the matter. All of this discussion about shared folders has prompted another question. Can you have two or more exact copies of the session folder running or are we limited to one location? bea271 mentioned two system for webroot. It is my understanding we would be limited to pointing at one webroot containing the same sessions for all the servers (in the context we are discussing of shared sessions on many servers for load but one app on all instances). I appreciate everyone's help I am learning from your experience so I don't waste lots of time trying to tinker with various load balancing setups to find it was a waste of time from the start.