Steelkiwi’s Experience Developing A Crm System For Client Management

Still not sure do you need a custom CRM or not? Just think about it: quality ready-made CRM solutions are expensive, while usually, your company does not need the whole set of provided functions. The cost of a custom CRM development also is not chip, however, when you are building a CRM system, you pay for the functions required particularly by your company. Plus, employees will not spend a lot of time exploring the new product, because CRM is initially created under the workflow, already established in the company.

availability groups – Will SQL Server go offline if it loses network connectivity to SAN where master and msdb system databases reside?

I have a setup where 3 servers participating in Availability Group

All 3 servers have local directly attached SSD drives, and user database files are hosted on these drives

But the system databases (master and msdb) of each server in AG, are hosted on a SAN device that is accessed over the network

Did not move those to local SSD drives yet


In a hypothetical situation where network connection between any of the servers and the SAN device is lost (bad cable, bad NIC, some temporary network glitch etc.),

Will SQL Server service on that server go offline or stop working properly immediately ?

Or it continues to work for some time if master and msdb were cached in RAM before network went down ?

Gauss-Krüger system to Unity Coordinate Conversion

In my recent project, I am getting an object file via a request to REST API and found that the OBJs (object file) are in Gauss-Kruger System. I want to know that how exactly I place the model as I have several objects so coordinate conversion should work between UCS(unity coordinate system) and Gauss Kruger System. Previously I am able to convert UCS to Lat Long via Unity GPS Conversion project.

domain name system – Can the IP address of a root nameserver change?

This is a question about DNS root nameservers.

In order to resolve DNS queries, to obtain nameservers for the first stage of the process, the root nameservers must be consulted.

There are 13 and the IP addresses of these servers can be viewed at

My understanding is that when a new device connects to the internet, it (probably) uses the nameservers provided by the ISP. (I don’t actually know how the IP addresses of these devices are obtained. Presumably some software in the router/hardware provided by the ISP?)

The ISP then knows the IP addresses of the root nameservers.

The question is what happens if those IP addresses change? Is this possible?

Taking a look at the ip addresses seem to be somewhat arbitary.

Presumably they are static and decided by ICAAN. Can the IP addresses of the root nameservers change? If so, what happens?

making a server management system / control panel

I’m making an open source server management system. I’m starting to make progress on it, so I’d like to share and see if anyone is intereste… | Read the rest of

unity – How to Make Saving System More Secure

Since you wrote in a comment it is for an offline game, the short answer is: you can’t.

If the player is the owner of the whole game (since it offline), any kind of mechnism can be prevented if he is dedicated enough to figure out how you obscured your data. You can only make it harder for him.

You need to prevent memory manipulation, else the player could either freeze his hitpoints, ammo, money, etc or increase it to his liking.

The second part is you need to protect the save file itself against manipulation. Since he can read it as well, you need to make it harder for him to read and change values. Binary files, custom formats and a hash of everything are doing the job. The draw back (if that is one for you) is, if he really tries to manipulate the file, he might create new run time errors when you try to read your own file since the format got broken (and the player will certainly blame it on you why all his items are gone)

There is the opinion that if the game is offline, you should let the player do what he wants. Maybe the game is too hard and he would otherwise stop playing. Maybe he is lacking time for farming. As long as he is the only player, all he can do is boost himself and has no effect on the play experience of other players.

Why is it considered hard to maintain strong consistency in a distributed system?

Why can’t you just use strongly consistent reads for all your DB reads, with retries on 500 responses? According to CAP theorem increasing consistency should probably lower availability, but can’t the decreased availability (increased 500 responses) be handled fairly easily using retries? (assuming you are fine with a small percentage of queries taking a bit longer due to retries)

Using DynamoDB as an example, but this can be generalized to any noSQL cloud offering – It also seems like DDB with on demand scaling will simply increase your read capacity units (RCU) used if you turn on strong consistency, incurring a higher cost ($) but keeping the same latency on db queries, so it seems like the negative is only higher cost. It seems like you can just keep vertical scaling the DB’s processing power to meet your needs. Is it actually plausible that with a noSQL cloud database with a high traffic level, you cannot just throw enough money at it, and it could hit some scaling limit to make strongly consistent reads slower?

And then with regard to the entire question generalized to distributed systems, what does it actually mean for a distributed system to be ‘strongly consistent.’ I’ve heard this used to describe systems before but I don’t actually know it means beyond ‘all DB interactions being strongly consistent.’

My second question might be more basic level but necessary to understand the cost of providing consistency, but why do consistent read issues actually occur, ie. why does stale data occur (in single queries like read/write, not transactions with multiple reads/writes per transaction)?

From what I understand, with decreasing probability any time after a write occurs, it’s possible for one reader to read correct data, then a second reader to read stale data AFTER the first reader reads correct data (correct me if this isn’t actually true, but my understanding was it is). Why does this happen? Doesn’t a read just involve a read from some location on the disk?

terminal – Allowing Java access to Mac’s Microphone system

I am writing a Java program that is trying to use my computer’s audio lines from the microphone to record audio. There seems to be a recurring issue where Mac users are unable to record – my resulting WAV files are the correct duration, but don’t have any sound. I’ve made a post on StackOverflow addressing this topic, and at the moment I think it might have to do with my Mac’s security not allowing access to the microphone to Java. I checked System Preferences -> Security & Privacy -> Privacy -> Microphone to see if I had to give express access to Java, but it is not one of the applications listed and there doesn’t seem to be a way to add it to the list.

Alternatively, I have tried loading each individual audio line and recording with those, but all the lines elicit the same result. I was wondering if there a different set of settings that are worth examining in System Preferences and/or anything I should execute on Terminal to change microphone access permissions?

I appreciate any guidance on this issue!

Does multiplying $A^T$ change the outcome of a linear system of equation?

Does this hold for all $x in R^n$? (If so how would you prove it?)
$$A^TAx = 0 LeftarrowRightarrow Ax=0$$

Class diagram of an Hotel Management System

I am given the following system description :

Consider a hotel
management system to manage a group of 5-stars hotels. If this system is modelled using OOP methodology, and the classes are identified as Hotel, Trip, Room, VIP Room, Regular Room, Suite, Customer, Payment, Cash_Payment, Credit_Debit_Payment, Reservation.

Now I need to draw its UML class diagram, here is my solution :
enter image description here

I have related the customer class indirectly with the Hotel using the reservation class which is related to the Room class and Trip class and both of them are related to the Hotel class is this a valid solution ?. Also, did I miss any composition or Aggregation relationships? Finally, are these multiplicities right? I am just participating in some problems for class diagrams to understand it, so please help me.