This time we’re going to take a look at the top common errors and pitfalls that can be easily avoided when developing and deploying a multiplayer game with SmartFoxServer 2X. The list is compiled from a selection of topics that are quite popular\u00a0in our support forums.<\/p>\n
Knowing about these common pitfalls can possibly save you a significant amount\u00a0of time and head scratching. Let’s see what they are.<\/p>\n
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When developing server side code the SFSApi class<\/a> is your best friend. It contains all of the most important methods you will ever need to implement your game logic: creating and joining rooms, setting variables,\u00a0disconnecting users, sending messages, and tons more.<\/p>\n Additionally all of the SFSApi calls take care of updating clients and generating server-side events.<\/p>\n Bottom line<\/strong>: whenever you need to tell the server to perform an action, check this class before anything else, chances are you will find what you need.<\/p>\n The SFSApi class<\/a> is super-easy to use as it is already instantiated behind the scenes in the main Extension class and all ClientRequest and ServerEvent handlers. You can access by calling the getApi()<\/strong> method in your code.<\/p>\n Additionally you can access the specialized API (BuddyList API<\/a>, Game API<\/a>) from this line of code:<\/p>\n This is likely the most popular problem recurring in the forums. When accessing\u00a0the database connection directly, instead of using the SFSDBManager class, there is extra care required to properly dispose of it at the end of the code.<\/p>\n The example above should serve as a code template for manual connection handling. Inside the try block<\/strong> we start by obtaining the connection from SFS2X connection pool.<\/p>\n Since connections are reused to improve performance, we must make sure that they are returned to the pool when the operation is complete. Failing to do this will leak the connection, which in turn won’t be reusable. If this happens too often all available connections will be exhausted causing all sort of problems.<\/p>\n The finally block<\/strong> is particularly important because it is the last thing that is executed before leaving the method, even when an exception is thrown.<\/p>\n If you find yourself writing code like this:<\/p>\n think again.<\/p>\n Writing data to the network inside a for-loop is a bad idea. In this example we’re generating a deluge of small packets, sent one after the other, while we could have simply packed all of the data in one object and send\u00a0in one shot. Like this:<\/p>\n Additionally the first example is creating 100 SFSObjects, each having its 3 byte header and thus wasting an extra 300 bytes.<\/p>\n Bottom line<\/strong>: if your code sends data inside a for-loop, rewrite the code so that the send call is outside the loop and your data is aggregated in one request.<\/p>\n High traffic game servers can host tens of thousands of players and thousands of Game Rooms. If you plan to reach these heights it would\u00a0be better to have a strategy for managing very big Room Lists.<\/p>\n If such a strategy is not in place clients will end up receiving ginormous lists of rooms that will waste lots of bandwidth and overwhelm\u00a0the clients with data.\u00a0Fortunately SFS2X provides a simple and efficient mechanism to organize Rooms into Groups and let users decide which of those they are interested in.<\/p>\n For more details on this topic we have a previous blog post, called Fine Tuning Room Lists<\/a>.<\/p>\n We have seen a number of projects where existing application API already exist in form of web services, often\u00a0written in PHP and connected to an existing database.\u00a0Typically these API handle a wide range of functionalities, from user profile management,\u00a0credentials, integration with other website features etc..<\/p>\n Integrating these services with a SmartFoxServer 2X is relatively simple. All you need is to perform HTTP calls from your Extension code to the web\u00a0server, wait for a response and finally reply to the client via socket.<\/p>\n On paper this looks like a great way to reuse existing services, without the hassle of\u00a0rewriting them in Java, but\u00a0unfortunately there is also a dark side to this approach which typically manifests in performance bottlenecks for SmartFoxServer: invoking remote HTTP services can be\u00a0slow or even painfully slow, depending on several factors.<\/p>\n We’ve seen HTTP calls taking between 1000 and 8000 milliseconds to return, while SFS2X was receiving 100-200 calls per second. You can easily do the math and see that this is a scalability nightmare.<\/p>\n The most radical solution to this problem is avoiding it entirely, by accessing the data source (e.g. database) without intermediaries (HTTP server, PHP etc…) This can provide a speed bump of several orders of magnitude and thus solving the issue altogether.<\/p>\n Bottom line<\/strong>: If you have the option of\u00a0choosing how to implement these services we absolutely positively recommend to access the datasource directly, you won’t regret it.<\/p>\n On the other hand, if this is not an option then we can only suggest to make sure that every step of the chain is carefully optimized, avoiding excessive lag between servers, improving the PHP performance with a compiler and checking the execution time of each query, optimizing those that don’t perform well enough.<\/p>\n\r\nSmartFoxServer.getInstance().getApiManager();\r\n<\/pre>\n
2) Manual database connection handling<\/h2>\n
\r\ntry\r\n{\r\n connection = dbManager.getConnection();\r\n \/\/ Your database code goes here\r\n}\r\ncatch(SQLException sqle)\r\n{\r\n \/\/ Here we handle the SQL failure\r\n}\r\nfinally\r\n{\r\n try\r\n {\r\n connection.close();\r\n }\r\n catch(SQLException sqle)\r\n {\r\n \/\/ It shouldn't happen, but if it does it's best to leave a trace in the logs\r\n }\r\n}<\/pre>\n3)\u00a0Sending data in for loops<\/h2>\n
\r\nfor (int i = 0; i < 100; i++)\r\n{\r\n\tSFSObject obj = new SFSObject();\r\n\tobj.putParam("var" + i, i);\r\n\r\n\tsfs.Send(new ExtensionRequest("cmd", obj));\r\n}\r\n<\/pre>\n\r\nSFSObject obj = new SFSObject();\r\n\r\nfor (int i = 0; i < 100; i++)\r\n{\r\n\tobj.putParam("var" + i, i);\r\n}\r\n\r\nsfs.Send(new ExtensionRequest("cmd", obj));\r\n<\/pre>\n4) Enormous Room Lists<\/h2>\n
5)\u00a0Calling slow remote services<\/h2>\n
6)\u00a0Creating too many Task Schedulers<\/h2>\n