I am not sure if I should be posting this question here or over at ServerFault so apologies if it is in the wrong place.
I have a small web app that is starting to get some more business.
Currently I have a single dedicated LAMP server for this, and this has worked well - the single server is able to handle all of our traffic.
However... Recently I have been approached by some potential customers who are interested in using the app, but only if their data can be stored on a server in the same province as they are (legal reasons).
I could migrate the server, but I am reluctant to do this. I like where it is now.
So, I am wondering what is involved in having multiple servers in physically separate datacentres far apart, running the same web app? Data between the servers would not need to stay synced, necessarily.
I have never done anything like this before, and am not sure how complicated a job it is. Any suggestions on how and where to start looking into this would be much appreciated.
Thanks (in advance) for your advice.
As long as each customer has their own set of data you can just install another copy of the application in the other datacenter. It will require you to get some structure to your source control and deployment process, but it works. This option will give you two separate databases.
If you have to have one common database for all the customers (e.g. some kind of booking/reservation system of common resources) then you're up to a completely other level of complexity with replicating databases etc. It's doable, but it's hard.
Related
We are currently testing an upgrade from CF11 to CF2018 for my company's intranet. To give you an idea how long this site has been running, our first version of CF was 3.1! It is still using application.cfm, and there is code from 1998, when I started writing this thing. Yes, 21 years -- I'm astonished, too. It is a hodgepodge of all kinds of older frameworks, too, including Fusebox.
Anyway, we're running Win 2012 VM connected to a SQL 2016 farm. Everything looked OK initially, but in the Week I've been testing, the server has come to a slowdown once (a page took more than 5 seconds to run, something that usually takes 100ms, no DB involvement), and another time, the server came to a grinding halt. The only way I could restart CF App service was by connecting to the server with another server via Services, because doing it via Remote Desktop was so slow.
Now keep in mind -- it's just me testing. This is a site that doesn't have a ton of users, but still, having 5 concurrent connections is normal and there are upwards of 200-400 users hitting this thing every day.
I have FusionReactor running on this thing now, so the next time a lockup happens, I will be able to take a closer look, but what do you think is the best way I can test this? Our site is mostly transactional, users going and filling out forms to put internal orders through. We also connect to XML web services and REST services; we also provide REST services, too. Obviously there's no way to completely replicate a production server's requests onto a test server, but I need to do more thorough testing. Any advice would be hugely appreciated.
I realize your focus for now is trying to recreate the problem on test. That may not be as easy as hoped. Instead, you should be able to understand and resolve it in production. FusionReactor can help, but the answer may well be in the cf logs.
You don't mention assessing the logs at the time of the hangup. See especially the coldfusion-error log, for outofmemory conditions.
You mention raising the heap, but the problem may be with the metaspace instead. If so, consider simply removing the maxmetaspace setting in the jvm args. That may be the sole and likely cause of such new and unexpected outages.
Or if it's not, and there's nothing in the logs at the time, THEN do consider FR. Does IT show anything happening at the time?
If not then consider a need to tune the cf/web server connector. I assume you're using iis. How many sites do you have? And how many connectors (folders in the cf config/wsconfig folder)? What are the settings in their workers.properties file? Are they optimized for the number of sites using that connector?
Also, have you updated cf2018? Are there any errors in the update error log? Did you update the web server connector also?
Are you running the cf2018 pmt (performance monitoring tool set)? Have you updated it?
There could be still more to consider, but let's see how it goes with those. I have blog posts on these and many more topics that would elaborate on things, both at my site (carehart.org) and the Adobe cf portal (coldfusion.adobe.com).
But let's hear if any of this gets you going.
For the moment, all my customers are in the same db, same domain etc… on my majestic monolith on https://www.mystartup.com.
Let’s say I want to deploy an instance of my rails app for one big customer. And let’s say I may deploy other instances of this rails app in the future.
The thing is that I am fetching and computing some heavy data, and I want to do it once instead of in all the instances. So I guess I should do them in https://secret-api.mystartup.com, and each of the instance should make requests to it with secret access token.
But my issue is this one : is there a way for https://secret-api.mystartup.com to trigger some calls to each of the domains, when needed? Is this what we call “webhooks”? or is there some double-way-api concept that I am missing?
One question you need to answer is that what if this secret-api server need to be restarted ! You loose all that heavy lifting computation..
Another problem with above solution is that it is going against micro-services architecture in a way.. because you are having a single server for secret-api.. What if this goes down; then your whole system goes down... With micro-services; for high availability you should always have multiple servers for same api.
For such scenarios; when there is heavy lifting to be done, one solution could be that have an in-memory layer in between something like memcached or redis..keep your solutions in this in-meory server and NOT inside a cache maintained inside your secret-api server.. This solution will solve both above mentioned problems.
I am building an app for a workshop at a conference. It will be used by the participants to input answers to a survey on their mobile devices and then these answers will be saved to a database.
I am currently looking at PostgreSQL and from what I have seen it is extremely capable of handling well over 100 expected users that I will have using the app at one time. What I haven't been able to decide conclusively is whether these 100 people all adding to the same database at once will cause any problems. I have looked into locks and understand that theres shouldn't be any conflicts when inserting into tables (which is all the users will be doing) but I just wanted to confirm before moving forward with the app.
I assume it is also important to deploy the app using a hosting service which can handle the load. I am intending to use Heroku which I have experience deploying postgreSQL databases to.
Just in case it is relevant I was intending to use Knex.js to build the database in a node backend.
Happy to provide any further information and would appreciate any input or better suggestions to look into.
Cheers,
Tim
I have a desktop app that clients are using at the moment and each client has access to their own local network database.
My manager has decided that its best to merge these databases and only have one. All clients would then access that one database through a webservice that sits on the cloud. I would like to weight the pros and cons before we go ahead with this decision.
The one option we have is to have a ClientID in each of the tables which will result in each table having a composite key .
I have heard that another option would be to use schemas .Please advise how the schema way would work and is this the best way in comparison to having a composite key in each table.
Thank you.
This is a seriously difficult and time consuming task. You will need to have extensive regression tests already built because the risk of things breaking is huge.
Let me tell you a story of a client that had a separate database on a separate suerver that got merged with another database that contained many clients. It took several months to make all the changes to convert the data. Everything looked good and it was pushed to prod. Unfortunately the developer missed one place where client id needed to be referenced (It usually wasn't in the old code since they were the only client on the server). The first day in production a process that sent out emails, sent client proprietary data not only to the client sales reps but to the sales reps of many of their competitors. Of all the places that the change could have been missed, this was the worst possible one. It not only harmed our relationship with the first client but with all the clients that got some other client's info by mistake.
There is also the problem of migrating the data, the project for that alone (without the code changes the application will need) will take months and then you have consider that the clients will be adding data as you go and the final push may run into unexpected hiccups due to new data. You may also have to turn off the odl system for at least a weekend to do the production change.
Using schemas won't make it any easier as you will then have to adjust the code to hit the correct schema per client. And when you change somethign you wil have to change it for each individual schema, so it tends to make the database much more difficult to maintain.
While I am a great fan of having multiple clients in one database, when you didn't start out that way, it is extremely risky and expensive to change. I would not do it al all unless I had these things:
Code in source control
Extensive Unit and regression tests
Separate dev, QA and prod environments
A process for client UAT testing
Extensive knowledge of how cloud computing and webservices works (everyone I know who has moved stuff to the cloud has had some real gotchas)
A QA department
Six months to one year time frame for the project
At least one senior data analyst on the team.
First let me say i am only a novice programmer, and by no means an sql guru. We have an app at work that is and has been under heavy dev from the vendor for sometime (2+ years). It runs as a MSSQL instance on one of our servers, and there is a client install for the desktops. The client software is making direct sql calls to the database.(it also has a local mysql instance to handle the client settings) there is 6-12 ports that had to be opened up for the communication. Looking at the sql manager, i can see direct sql calls from various clients.
Seems to me this is entirely the wrong approach. the closest thing i have done to this, was a webpage + php+ mysql. The webpage would make requests, and all the processing would be serverside, then simply display the results. The sluggishness my users feel i think is from the clientside request+ processing of the sql data.
ps: i realize that if they have not done it by now, switching to another paradigm seems out of the question. i just want to know if i am way off base.
You are way off base.
The client side has much more processing power.
Consider the case of one server and 5 clients. Even is the server has 3 times the power of a client the clients as a whole are still 5:3 more powerful.
If the application is sluggish it was probably poorly written. You need to investigate the root cause. Client / Server is a leading practice in design, I'm guessing it is not the root cause. It might be badly implemented or there might be other reasons. Your comment about having a local mysql sounds very fishy to me -- there should be no need for this.