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Search found 11 results on 1 pages for 'alexeypro'.

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  • Zero downtime deployment (Tomcat), Nginx or HAProxy, behind hardware LB - how to "starve" old server?

    - by alexeypro
    Currently we have the following setup. Hardware Load Balancer (LB) Box A running Tomcat on 8080 (TA) Box B running Tomcat on 8080 (TB) TA and TB are running behind LB. For now it's pretty complicated and manual job to take Box A or Box B out of LB to do the zero downtime deployment. I am thinking to do something like this: Hardware Load Balancer (LB) Box A running Nginx on 8080 (NA) Box A running Tomcat on 8081 (TA1) Box A running Tomcat on 8082 (TA2) Box B running Nginx on 8080 (NB) Box B running Tomcat on 8081 (TB1) Box B running Tomcat on 8082 (TB2) Basically LB will be directing traffic between NA and NB now. On each of Nginx's we'll have TA1, TA2 and TB1, TB2 configured as upstream servers. Once one of the upstreams's healthcheck page is unresponsive (shutdown) the traffic goes to another one (HttpHealthcheckModule module on Nginx). So the deploy process is simple. Say, TA1 is active with version 0.1 of the app. Healthcheck on TA1 is OK. We start TA2 with Healthcheck on it as ERROR. So Nginx is not talking to it. We deploy app version 0.2 to TA2. Make sure it works. Now, we switch the Healthcheck on TA2 to OK, switch Healthcheck to TA1 to ERROR. Nginx will start serving TA2, and will remove TA1 out of rotation. Done! And now same with the other box. While it sounds all cool and nice, how do we "starve" the Nginx? Say we have pending connections, some users on TA1. If we just turn it off, sessions will break (we have cookie-based sessions). Not good. Any way to starve traffic to one of the upstream servers with Nginx? Thanks!

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  • Cassandra/HBase or just MySQL: Potential problems doing the next thing

    - by alexeypro
    Say I have "user". It's the key. And I need to keep "user count". I am planning to have record with key "user" and value "0" to "9999+ ;-)" (as many as I'll have). What problems I will drive in if I use Cassandra, HBase or MySQL for that? Say, I have thousand of new updates to this "user" key, where I need to increment the value. Am I in trouble? Locked for writes? Any other way of doing that? Why this is done -- there will be a lot of "user"-like keys. Different other cases. But the idea is the same. Why keep it this way -- because I'll have more reads, so I can always get "counted value" very fast.

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  • noSQL/SQL/RoR: Trying to build scalable ratings table for the game

    - by alexeypro
    I am trying to solve complex thing (as it looks to me). I have next entities: PLAYER (few of them, with names like "John", "Peter", etc.). Each has unique ID. For simplicity let's think it's their name. GAME (few of them, say named "Hide and Seek", "Jump and Run", etc.). Same - each has unique ID. For simplicity of the case let it be it's name for now. SCORE (it's numeric). So, how it works. Each PLAYER can play in multiple GAMES. He gets some SCORE in every GAME. I need to build rating table -- and not one! Table #1: most played GAMES Table #2: best PLAYERS in all games (say the total SCORE in every GAME). Table #3: best PLAYERS per GAME (by SCORE in particularly that GAME). I could be build something straight right away, but that will not work. I will have more than 10,000 players; and 15 games, which will grow for sure. Score can be as low as 0, and as high as 1,000,000 (not sure if higher is possible at this moment) for player in the game. So I really need some relative data. Any suggestions? I am planning to do it with SQL, but may be just using it for key-value storage; anything -- any ideas are welcome. Thank you!

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  • Strategy Design Pattern -- *dynamic* !!!

    - by alexeypro
    My application will have different strategies for my objects. What's the best way of implementing that? I would really love the case when we can make strategy classes implementation dynamically loaded from, say, some relational database. Not sure how do that better, though. What's the best approach? Idea is that say we want to apply to object MyObj strategy Strategy123 then we just load from database by ID 123 the object, deserialize it, get the Strategy class, and use it with MyObj. The maintenance while sounds easier from the first look can be a pain in the long run if Strategy interfaces changes, etc. What can I do also? I want to find solution when I should be keeping Strategy classes in codebase -- just for the sake that I don't need code change and re-deployment of the application if my Strategy changes, or I add new strategy. Please advise!

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  • Ooutsourcing design/programming (taxes!)

    - by alexeypro
    Hello, I have a full time job, but I also have some ideas in mind -- and I want to outsource some code development and design to Russia. I have friends there who help me to do that -- they'll do the development, provide me invoice (which is just description of our terms, because we decided on flat rate monthly fee), and I need to wire them money. So, I do not have business entity. If I'll pay them, am I am required to pay taxes? Or do I deduct my business expenses (say $30K/year) from my earnings (say $50K/year), and pay taxes only on what's left ($20K to be precise)? Any rules on that? Am I limited with something here? Thanks!

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  • Easiest (simple) explanation of "prototype" in JavaScript?

    - by alexeypro
    Hello, Can somebody give me a resource (or just explanation? :-) of what "prototype" is and how it works in Javascript. May be comparison with something in Java? (not really necessary). But it should be as simple/easy as possible so inexperienced person just learning Javascript would understand (need to explain this to jr designer who is proficient with CSS/HTML, but not with Javascript). Thank you!

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  • Searches (and general querying) with HBase and/or Cassandra (best practices?)

    - by alexeypro
    I have User model object with quite few fields (properties, if you wish) in it. Say "firstname", "lastname", "city" and "year-of-birth". Each user also gets "unique id". I want to be able to search by them. How do I do that properly? How to do that at all? My understanding (will work for pretty much any key-value storage -- first goes key, then value) u:123456789 = serialized_json_object ("u" as a simple prefix for user's keys, 123456789 is "unique id"). Now, thinking that I want to be able to search by firstname and lastname, I can save in: f:Steve = u:384734807,u:2398248764,u:23276263 f:Alex = u:12324355,u:121324334 so key is "f" - which is prefix for firstnames, and "Steve" is actual firstname. For "u:Steve" we save as value all user id's who are "Steve's". That makes every search very-very easy. Querying by few fields (properties) -- say by firstname (i.e. "Steve") and lastname (i.e. "l:Anything") is still easy - first get list of user ids from "f:Steve", then list from "l:Anything", find crossing user ids, an here you go. Problems (and there are quite a few): Saving, updating, deleting user is a pain. It has to be atomic and consistent operation. Also, if we have size of value limited to some value - then we are in (potential) trouble. And really not of an answer here. Only zipping the list of user ids? Not too cool, though. What id we want to add new field to search by. Eventually. Say by "city". We certainly can do the same way "c:Los Angeles" = ..., "c:Chicago" = ..., but if we didn't foresee all those "search choices" from the very beginning, then we will have to be able to create some night job or something to go by all existing User records and update those "c:CITY" for them... Quite a big job! Problems with locking. User "u:123" updates his name "Alex", and user "u:456" updates his name "Alex". They both have to update "f:Alex" with their id's. That means either we get into overwriting problem, or one update will wait for another (and imaging if there are many of them?!). What's the best way of doing that? Keeping in mind that I want to search by many fields? P.S. Please, the question is about HBase/Cassandra/NoSQL/Key-Value storages. Please please - no advices to use MySQL and "read about" SELECTs; and worry about scaling problems "later". There is a reason why I asked MY question exactly the way I did. :-)

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  • Hadoop Map/Reduce - simple use example to do the following...

    - by alexeypro
    I have MySQL database, where I store the following BLOB (which contains JSON object) and ID (for this JSON object). JSON object contains a lot of different information. Say, "city:Los Angeles" and "state:California". There are about 500k of such records for now, but they are growing. And each JSON object is quite big. My goal is to do searches (real-time) in MySQL database. Say, I want to search for all JSON objects which have "state" to "California" and "city" to "San Francisco". I want to utilize Hadoop for the task. My idea is that there will be "job", which takes chunks of, say, 100 records (rows) from MySQL, verifies them according to the given search criteria, returns those (ID's) which qualify. Pros/cons? I understand that one might think that I should utilize simple SQL power for that, but the thing is that JSON object structure is pretty "heavy", if I put it as SQL schemas, there will be at least 3-5 tables joins, which (I tried, really) creates quite a headache, and building all the right indexes eats RAM faster than I one can think. ;-) And even then, every SQL query has to be analyzed to be utilizing the indexes, otherwise with full scan it literally is a pain. And with such structure we have the only way "up" is just with vertical scaling. But I am not sure it's the best option for me, as I see how JSON objects will grow (the data structure), and I see that the number of them will grow too. :-) Help? Can somebody point me to simple examples of how this can be done? Does it make sense at all? Am I missing something important? Thank you.

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  • Please help with choosing CI build tool

    - by alexeypro
    Hello, I need to choose the right CI build tool which will: 1. Support groups of build configurations so we can use the standardized build process for all our projects 2. Support dashboard with "pretty" (for executive/director "eye" :-) reports. 3. Support Java, Maven, Ant, and be somewhat customizable for build process itself (though this is optional, as I can "fix" it with scripts) I'd prefer free and open source tool, but paid version is fine too. Please help :-)

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