iControl Library For Java With Source
Included are the binary distribution of the iControl library for Java and Apache Axis. These releases coincides through version BIG-IP, version 13.0.0. iControl Assembly for Java 11.3.0 iControl Assembly for Java 11.4.0 iControl Assembly for Java 11.4.1 iControl Assembly for Java 11.5.0 iControl Assembly for Java 11.6.0 iControl Assembly for Java 12.0.0 iControl Assembly for Java 12.1.0 iControl Assembly for Java 13.0.0 iControl Assembly for Java 13.1.0 The source distribution of the iControl library for Java with Apache Axis. These releases coincide through version BIG-IP, version 12.1.0. The source code for this project is no longer maintained but available at our at f5-icontrol-library-java repository on GitHub. iControl Assembly Java Source 11.4.0 (older release not available on Github) iControl Assembly Java Source 11.4.1 iControl Assembly Java Source 11.5.0 iControl Assembly Java Source 11.6.0 iControl Assembly Java Source 12.1.0Getting Started with iControl Code Samples
Problem this snippet solves: This repository on github is for the full scripts highlighted in the Getting Started with iControl article series. Developed against BIG-IP TMOS version 12.0, but should work in most versions 11.6+. How to use this snippet: Choose your language and iControl portal of choice to start investigating iControl in your environment. Target audience: beginners. Code : https://github.com/f5devcentral/iControl-GettingStarted Tested this on version: 12.0SSL Trust Provider for Java
I've blogged about Self-signed Server Certificates and how they can cause havoc with client java applications. We'll I put the call out there to provide solutions and a very slick one has arrived! XTrustProvider.java: /* * The contents of this file are subject to the "END USER LICENSE AGREEMENT FOR F5 * Software Development Kit for iControl"; you may not use this file except in * compliance with the License. The License is included in the iControl * Software Development Kit. * * Software distributed under the License is distributed on an "AS IS" * basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See * the License for the specific language governing rights and limitations * under the License. * * The Original Code is iControl Code and related documentation * distributed by F5. * * Portions created by F5 are Copyright (C) 1996-2004 F5 Networks * Inc. All Rights Reserved. iControl (TM) is a registered trademark of * F5 Networks, Inc. * * Alternatively, the contents of this file may be used under the terms * of the GNU General Public License (the "GPL"), in which case the * provisions of GPL are applicable instead of those above. If you wish * to allow use of your version of this file only under the terms of the * GPL and not to allow others to use your version of this file under the * License, indicate your decision by deleting the provisions above and * replace them with the notice and other provisions required by the GPL. * If you do not delete the provisions above, a recipient may use your * version of this file under either the License or the GPL. */ import java.security.AccessController; import java.security.InvalidAlgorithmParameterException; import java.security.KeyStore; import java.security.KeyStoreException; import java.security.PrivilegedAction; import java.security.Security; import java.security.cert.X509Certificate; import javax.net.ssl.ManagerFactoryParameters; import javax.net.ssl.TrustManager; import javax.net.ssl.TrustManagerFactorySpi; import javax.net.ssl.X509TrustManager; public final class XTrustProvider extends java.security.Provider { private final static String NAME = "XTrustJSSE"; private final static String INFO = "XTrust JSSE Provider (implements trust factory with truststore validation disabled)"; private final static double VERSION = 1.0D; public XTrustProvider() { super(NAME, VERSION, INFO); AccessController.doPrivileged(new PrivilegedAction() { public Object run() { put("TrustManagerFactory." + TrustManagerFactoryImpl.getAlgorithm(), TrustManagerFactoryImpl.class.getName()); return null; } }); } public static void install() { if(Security.getProvider(NAME) == null) { Security.insertProviderAt(new XTrustProvider(), 2); Security.setProperty("ssl.TrustManagerFactory.algorithm", TrustManagerFactoryImpl.getAlgorithm()); } } public final static class TrustManagerFactoryImpl extends TrustManagerFactorySpi { public TrustManagerFactoryImpl() { } public static String getAlgorithm() { return "XTrust509"; } protected void engineInit(KeyStore keystore) throws KeyStoreException { } protected void engineInit(ManagerFactoryParameters mgrparams) throws InvalidAlgorithmParameterException { throw new InvalidAlgorithmParameterException( XTrustProvider.NAME + " does not use ManagerFactoryParameters"); } protected TrustManager[] engineGetTrustManagers() { return new TrustManager[] { new X509TrustManager() { public X509Certificate[] getAcceptedIssuers() { return null; } public void checkClientTrusted(X509Certificate[] certs, String authType) { } public void checkServerTrusted(X509Certificate[] certs, String authType) { } }}; } } } Calling Application: ... XTrustProvider.install(); ... This file is up in CodeShare for those who are cut+paste challenged B-). Hat tip to Exnihilo for posting this solution! -Joe [Listening to: Ob-La-Di, Ob-La-Da - The Beatles - The White Album (03:08)]
Java application persistence issue with load balancer
I have a java application running on 2 web servers, load balanced in round robin fashion and cookie insert persistence on VIP. From what I understand of the application, it keeps doing some kind of pulse check with server every few seconds because of which the java app disconnects as it is getting bounced bw one server and other, meaning persistence is not working for subsequent connections made by the java applet. I cannot use source/dest_addr persistence, so it has to be cookie persistence. I somehow managed to disable the pulse check within application, which made the app stable and no disconnects were noticed. However after a while some of the tabs/pages started to throw errors which I believe is due to server switch at the F5 load balancing. Any ideas what else can be done to ensure the java application connection made to one server is persistent for subsequent connections made from same source?
Android Encrypted Databases
The Android development community, as might be expected, is a pretty vibrant community with a lot of great contributors helping people out. Since Android is largely based upon Java, there is a lot of skills reusability between the Java client dev community and the Android Dev community. As I mentioned before, encryption as a security topic is perhaps the weakest link in that community at this time. Perhaps, but since that phone/tablet could end up in someone else’s hands much more easily than your desktop or even laptop, it is something that needs a lot more attention from business developers. When I set out to write my first complex app for Android, I determined to report back to you from time-to-time about what needed better explanation or intuitive solutions. Much has been done in the realm of “making it easier”, except for security topics, which still rank pretty low on the priority list. So using encrypted SQLite databases is the topic of this post. If you think it’s taking an inordinate amount of time for me to complete this app, consider that I’m doing it outside of work. This blog was written during work hours, but all of the rest of the work is squeezed into two hours a night on the nights I’m able to dedicate time. Which is far from every night. For those of you who are not developers, here’s the synopsis so you don’t have to paw through code with us: It’s not well documented, but it’s possible, with some caveats. I wouldn’t use this method for large databases that need indexes over them, but for securing critical data it works just fine. At the end I propose a far better solution that is outside the purview of app developers and would pretty much have to be implemented by the SQLite team. Okay, only developers left? Good. In my research, there were very few useful suggestions for designing secure databases. They fall into three categories: 1. Use the NDK to write a variant of SQLite that encrypts at the file level. For most Android developers this isn’t an option, and I’m guessing the SQLite team wouldn’t be thrilled about you mucking about with their database – it serves a lot more apps than yours. 2. Encrypt the entire SD card through the OS and then store the DB there. This one works, but slows the function of the entire tablet/phone down because you’ve now (again) mucked with resources used by other apps. I will caveat that if you can get your users to do this, it is the currently available solution that allows indices over encrypted data. 3. Use one of several early-beta DB encryption tools. I was uncomfortable doing this with production systems. You may feel differently, particularly after some of them have matured. I didn’t like any of these options, so I did what we’ve had to do in the past when a piece of data was so dangerous in the wrong hands it needed encrypting. I wrote an interface to the DB that encrypts and decrypts as data is inserted and removed. In Android the only oddity you won’t find in other Java environments – or you can more easily get around in other Java environments – is filling list boxes from the database. For that I had to write a custom provider that took care of on-the-fly decryption and insertion to the list. My solution follows. There are a large varieties of ways that you could solve this problem in Java, this one is where I went because I don’t have a lot of rows for any given table. The data does not need to be indexed. If either of these items is untrue for your implementation, you’ll either have to modify this implementation or find an alternate solution. So first the encryption handler. Note that in this sample, I chose to encode encrypted arrays of bytes as Strings. I do not guarantee this will work for your scenario, and suggest you keep them as arrays of bytes until after decryption. Also note that this sample was built from a working one by obfuscating what the actual source did and making some modifications for simplification of example. It was not tested after the final round of simplification, but should be correct throughout. package com.company.monitor; import javax.crypto.Cipher; import javax.crypto.spec.SecretKeySpec; import android.util.Base64; public class DBEncryptor { private static byte[] key; private static String cypherType = cypherType; public DBEncryptor(String localPass) { // save the encoded key for future use // - note that this keeps it in memory, and is not strictly safe key = encode(localPass.getBytes()).getBytes(); String keyCopy = new String(key); while(keyCopy.length() < 16) keyCopy = keyCopy + keyCopy; byte keyA[] = keyCopy.getBytes(); if(keyA.length > 16) key = System.arraycopy(keyA, 0, key, 0, 16); } public String encode(byte [] s) { return Base64.encodeToString(s, Base64.URL_SAFE); } public byte[] decode(byte[] s) { return Base64.decode(s, Base64.URL_SAFE); } public byte[] getKey() { // return a copy of the key. return key.clone(); } public String encrypt(String toEncrypt) throws Exception { //Create your Secret Key Spec, which defines the key transformations SecretKeySpec skeySpec = new SecretKeySpec(key, cypherType); //Get the cipher Cipher cipher = Cipher.getInstance(cypherType); //Initialize the cipher cipher.init(Cipher.ENCRYPT_MODE, skeySpec); //Encrypt the string into bytes byte[ ] encryptedBytes = cipher.doFinal(toEncrypt.getBytes()); //Convert the encrypted bytes back into a string String encrypted = encode(encryptedBytes); return encrypted; } public String decrypt(String encryptedText) throws Exception { // Get the secret key spec SecretKeySpec skeySpec = new SecretKeySpec(key, cypherType); // create an AES Cipher Cipher cipher = Cipher.getInstance(cypherType); // Initialize it for decryption cipher.init(Cipher.DECRYPT_MODE, skeySpec); // Get the decoded bytes byte[] toDecrypt = decode(encryptedText.getBytes()); // And finally, do the decryption. byte[] clearText = cipher.doFinal(toDecrypt); return new String(clearText); } } So what we are essentially doing is base-64 encoding the string to be encrypted, and then encrypting the base-64 value using standard Java crypto classes. We simply reverse the process to decrypt a string. Note that this class is also useful if you’re storing values in the Properties file and wish them to be encrypted, since it simply operates on strings. The value you pass in to create the key needs to be something that is unique to the user or tablet. When it comes down to it, this is your password, and should be treated as such (hence why I changed the parameter name to localPass). For seasoned Java developers, there’s nothing new on Android at this juncture. We’re just encrypting and decrypting data. Next it does leave the realm of other Java platforms because the database is utilizing SQLite, which is not generally what you’re writing Java to outside of Android. Bear with me while we go over this class. The SQLite database class follows. Of course this would need heavy modification to work with your database, but the skeleton is here. Note that not all fields have to be encrypted. You can mix and match, no problems at all. That is one of the things I like about this solution, if I need an index for any reason, I can create an unencrypted field of a type other than blob and index on it. package com.company.monitor; import android.content.ContentValues; import android.content.Context; import android.database.Cursor; import android.database.sqlite.SQLiteDatabase; import android.database.sqlite.SQLiteDatabase.CursorFactory; import android.database.sqlite.SQLiteOpenHelper; public class DBManagernames extends SQLiteOpenHelper { public static final String TABLE_NAME = "Map"; public static final String COLUMN_ID = "_id"; public static final String COLUMN_LOCAL = "Local"; public static final String COLUMN_WORLD = "World"; private static int indexId = 0; private static int indexLocal = 1; private static int indexWorld = 2; private static final String DATABASE_NAME = "Mappings.db"; private static final int DATABASE_VERSION = 1; // SQL statement to create the DB private static final String DATABASE_CREATE = "create table " + TABLE_NAME + "(" + COLUMN_ID + " integer primary key autoincrement, " + COLUMN_LOCAL + " BLOB not null, " + COLUMN_WORLD +" BLOB not null);"; public DBManagernames(Context context, CursorFactory factory) { super(context, DATABASE_NAME, factory, DATABASE_VERSION); } @Override public void onCreate(SQLiteDatabase db) { db.execSQL(DATABASE_CREATE); } @Override public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) { // TODO Auto-generated method stub // Yeah, this isn't implemented in production yet either. It's low on the list, but definitely "on the list" } // Assumes DBEncryptor was used to convert the fields of name before calling insert public void insertToDB(DBNameMap name) { ContentValues cv = new ContentValues(); cv.put(COLUMN_LOCAL, name.getName().getBytes()); cv.put(COLUMN_WORLD, name.getOtherName().getBytes()); getWritableDatabase().insert(TABLE_NAME, null, cv); } // returns the encrypted values to be manipulated with the decryptor. public DBNameMap readFromDB(Integer index) { SQLiteDatabase db = getReadableDatabase(); DBNameMap hnm = new DBNameMap(); Cursor cur = null; try { cur = db.query(TABLE_NAME, null, "_id='"+index.toString() +"'", null, null, null, COLUMN_ID); // cursors connsistently return before the first element. Move to the first. cur.moveToFirst(); byte[] name = cur.getBlob(indexLocal); byte [] othername = cur.getBlob(indexWorld); hnm = new DBNameMap(new String(name), new String(othername), false); } catch(Exception e) { System.out.println(e.toString()); // Do nothing - we want to return the empty host name map. } return hnm; } // NOTE: This routine assumes "String name" is the encrypted version of the string. public DBNameMap getFromDBByName(String name) { SQLiteDatabase db = getReadableDatabase(); Cursor cur = null; String check = null; try { // Note - the production version of this routine actually uses the "where" field to get the correct // element instead of looping the table. This is here for your debugging use. cur = db.query(TABLE_NAME, null, null, null, null, null, null); for(cur.moveToFirst();(!cur.isLast());cur.moveToNext()) { check = new String(cur.getBlob(indexLocal)); if(check.equals(name)) return new DBNameMap(check, new String(cur.getBlob(indexWorld)), false); } if(cur.isLast()) return new DBNameMap(); return new DBNameMap(cur.getString(indexLocal), cur.getString(indexWorld), false); } catch(Exception e) { System.out.println(e.toString()); return new DBNameMap(); } } // used by our list adapter - coming next in the blog. public Cursor getCursor() { try { return getReadableDatabase().query(TABLE_NAME, null, null, null, null, null, null); } catch(Exception e) { System.out.println(e.toString()); return null; } } // This is used in our list adapter for mapping to fields. public String[] listColumns() { return new String[] {COLUMN_LOCAL}; } } I am not including the DBNameMap class, as it is a simple container that has two string fields and maps one name to another. Finally, we have the List Provider. Android requires that you populate lists with a provider, and has several base ones to work with. The problem with the SimpleCursorAdapter is that it assumes an unencrypted database, and we just invested a ton of time making the DB encrypted. There are several possible solutions to this problem, and I present the one I chose here. I extended ResourceCursorAdapter and implemented decryption right in the routines, leaving not much to do in the list population section of my activity but to assign the correct adapter. package com.company.monitor; import android.content.Context; import android.database.Cursor; import android.view.LayoutInflater; import android.view.View; import android.view.ViewGroup; import android.widget.ResourceCursorAdapter; import android.widget.TextView; public class EncryptedNameAdapter extends ResourceCursorAdapter { private String pw; public EncryptedHostNameAdapter(Context context, int layout, Cursor c, boolean autoRequery) { super(context, layout, c, autoRequery); } public EncryptedHostNameAdapter(Context context, int layout, Cursor c, int flags) { super(context, layout, c, flags); } // This class must know what the encryption key is for the DB before filling the list, // so this call must be made before the list is populated. The first call after the constructor works. public void setPW(String pww) { pw = pww; } @Override public View newView(Context context, Cursor cur, ViewGroup parent) { LayoutInflater li = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE); return li.inflate(R.layout.my_list_entry, parent, false); } @Override public void bindView(View arg0, Context arg1, Cursor arg2) { // Get an encryptor/decryptor for our data. DBEncryptor enc = new DBEncryptor(pw); // Get the TextView we're placing the data into. TextView tvLocal = (TextView)arg0.findViewById(R.id.list_entry_name); // Get the bytes from the cursor byte[] bLocal = arg2.getBlob(arg2.getColumnIndex(DBManagerNames.COLUMN_LOCAL )); // Convert bytes to a string String local = new String(bSite); try { // decrypt the string local = enc.decrypt(local); } catch(Exception e) { System.out.println(e.toString()); // local holds the encrypted version at this point, fix it. // We’ll return an empty string for simplicity local = new String(); } tvSite.setText(local); } } The EncryptedNameAdapter can be set as the source for any listbox just like most examples set an ArrayAdapter as the source. Of course, it helps if you’ve put some data in the database first . That’s it for this time. There’s a lot more going on with this project, and I’ll present my solution for SSL certificate verification some time in the next couple of weeks, but for now if you need to encrypt some fields of a database, this is one way to get it done. Ping me on any of the social media outlets or here in the comments if you know of a more elegant/less resource intensive solution, always up for learning more. And please, if you find an error, it was likely introduced in the transition to something I was willing to throw out here publicly, but let me know so others don’t have problems. I’ve done my best not to introduce any, but always get a bit paranoid if I changed it after my last debug session – and I did to simplify and sanitize.iControl with Java - Retrieve List of Virtual Servers does not include Applications
Hi, i connect to the F5 using the Java Wrapper API; Now, when i get the list of Virtual-Servers via iControlInterfaces.getLocalLBVirtualServer().get_list() it only returns the virtual servers that are not created with an application (i.e. with the f5.microsoft_exchange_2010_2013_cas template). I could not find any way to further "open" the list; How can i retrieve these too? Many thanks in advance! Rene
iControl transaction problem
Here is my code written with iControl Library for Java. // set timeout interfaces.getSystemSession().set_session_timeout(60); interfaces.getSystemSession().set_transaction_timeout(30); // get transaction final long sessionId = interfaces.getSystemSession().get_session_identifier(); interfaces.getSystemSession().setHeader("urn:iControl", "session", Long.toString(sessionId)); interfaces.getLocalLBPool().setHeader("urn:iControl","session",Long.toString(sessionId); // start transaction interfaces.getSystemSession().submit_transaction(); // create pool1 interfaces.getLocalLBPool().create_v2(poolname1, lbmethod1, addressport1); // sleep 30 sec to wait transaction will be expired Thread.sleep(30000); // create pool2 interfaces.getLocalLBPool().create_v2(poolname2, lbmethod2, addressport2); // submit transaction interfaces.getSystemSession().submit_transaction(); I expected that creating both pool1 and pool2 would be rollbacked, but pool2 was succesfully created. Is there a way to detect transaction expiration and roleback all configuration in transaction ?How to access RDP from Mac OSX on BIG-IP APM 12.0
Hello Devcentral, First of, there have been many "MAC OSX RDP" topics on here, I think I've read through all of them but I still cannot seem to get RDP working for my MAC OSX users. As with our Windows users I want them to be able to log onto the BIG-IP APM, click a link (Application Tunnel for MAC OSX of course) and then have them be able to log onto a Windows Server through RDP. I'm getting Java errors, "ClassNotFoundException" from the AppletTunnelProxy (seems to be something wrong with f5apptunnel.jar?). I've tried JRE 1.8 and 1.7 on my test Mac Mini here (OSX 10.11.6 El Capitan) and using Safari as well as Firefox. I did get this to work on BIG-IP APM 11.6 if I recall correctly. Any help on this would be greatly appreciated. I have Java error logs/traces but didn't want to immediately spam this topic. If need be I can paste them into here. Thanks in advance!Java System Info
Problem this snippet solves: This Java application illustrates how to query system information from a BIG-IP with Java. This sample is the companion code for the "Getting Started With iControl And Java - Setting Up Eclipse" Tech Tip on DevCentral. It illustrates how to setup the iControl interfaces object and query system information from the BIG-IP with Java and iControl. Code : public class SystemInfo { public iControl.Interfaces m_interfaces = new iControl.Interfaces(); public void usage() { System.out.println("Usage: SystemInfo hostname username password"); } public void Run(String [] args) throws Exception { if ( args.length < 3 ) { usage(); } else { String host = args[0]; String user = args[1]; String pass = args[2]; boolean bInit = m_interfaces.initialize(host, user, pass); if ( bInit ) { getSystemInformation(); } } } public void getSystemInformation() throws Exception { iControl.SystemSystemInformation sysInfo = m_interfaces.getSystemSystemInfo().get_system_information(); System.out.println("======================================================"); System.out.println(" System Information"); System.out.println("------------------------------------------------------"); System.out.println("System Name : " + sysInfo.getSystem_name()); System.out.println("Host name : " + sysInfo.getHost_name()); System.out.println("OS Release : " + sysInfo.getOs_release()); System.out.println("OS Machine : " + sysInfo.getOs_machine()); System.out.println("OS Version : " + sysInfo.getOs_version()); System.out.println("Platform : " + sysInfo.getPlatform()); System.out.println("Product Category : " + sysInfo.getProduct_category()); System.out.println("Chassis Serial : " + sysInfo.getChassis_serial()); System.out.println("Switch Board Serial : " + sysInfo.getSwitch_board_serial()); System.out.println("Switch Board Part Revision : " + sysInfo.getSwitch_board_part_revision()); System.out.println("Host Board Serial : " + sysInfo.getHost_board_serial()); System.out.println("host Board Part Revision : " + sysInfo.getHost_board_part_revision()); System.out.println("Annunciator Board Serial : " + sysInfo.getAnnunciator_board_serial()); System.out.println("Annunciator Board Part Revision : " + sysInfo.getAnnunciator_board_part_revision()); } /** * @param args */ public static void main(String[] args) { try { SystemInfo sysInfo = new SystemInfo(); sysInfo.Run(args); } catch(Exception ex) { ex.printStackTrace(System.out); } } }2.5 bad ways to implement a server load balancing architecture
I'm in a bit of mood after reading a Javaworld article on server load balancing that presents some fairly poor ideas on architectural implementations. It's not the concepts that are necessarily wrong; they will work. It's the architectures offered as a method of load balancing made me do a double-take and say "What?" I started reading this article because it was part 2 of a series on load balancing and this installment focused on application layer load balancing. You know, layer 7 load balancing. Something we at F5 just might know a thing or two about. But you never know where and from whom you'll learn something new, so I was eager to dive in and learn something. I learned something alright. I learned a couple of bad ways to implement a server load balancing architecture. TWO LOAD BALANCERS? The first indication I wasn't going to be pleased with these suggestions came with the description of a "popular" load-balancing architecture that included two load balancers: one for the transport layer (layer 4) and another for the application layer (layer 7). In contrast to low-level load balancing solutions, application-level server load balancing operates with application knowledge. One popular load-balancing architecture, shown in Figure 1, includes both an application-level load balancer and a transport-level load balancer. Even the most rudimentary, entry level load balancers on the market today - software and hardware, free and commercial - can handle both transport and application layer load balancing. There is absolutely no need to deploy two separate load balancers to handle two different layers in the stack. This is a poor architecture introducing unnecessary management and architectural complexity as well as additional points of failure into the network architecture. It's bad for performance because it introduces additional hops and points of inspection through which application messages must flow. To give the author credit he does recognize this and offers up a second option to counter the negative impact of the "additional network hops." One way to avoid additional network hops is to make use of the HTTP redirect directive. With the help of the redirect directive, the server reroutes a client to another location. Instead of returning the requested object, the server returns a redirect response such as 303. I found it interesting that the author cited an HTTP response code of 303, which is rarely returned in conjunction with redirects. More often a 302 is used. But it is valid, if not a bit odd. That's not the real problem with this one, anyway. The author claims "The HTTP redirect approach has two weaknesses." That's true, it has two weaknesses - and a few more as well. He correctly identifies that this approach does nothing for availability and exposes the infrastructure, which is a security risk. But he fails to mention that using HTTP redirects introduces additional latency because it requires additional requests that must be made by the client (increasing network traffic), and that it is further incapable of providing any other advanced functionality at the load balancing point because it essentially turns the architecture into a variation of a DSR (direct server return) configuration. THAT"S ONLY 2 BAD WAYS, WHERE'S THE .5? The half bad way comes from the fact that the solutions are presented as a Java based solution. They will work in the sense that they do what the author says they'll do, but they won't scale. Consider this: the reason you're implementing load balancing is to scale, because one server can't handle the load. A solution that involves putting a single server - with the same limitations on connections and session tables - in front of two servers with essentially the twice the capacity of the load balancer gains you nothing. The single server may be able to handle 1.5 times (if you're lucky) what the servers serving applications may be capable of due to the fact that the burden of processing application requests has been offloaded to the application servers, but you're still limited in the number of concurrent users and connections you can handle because it's limited by the platform on which you are deploying the solution. An application server acting as a cluster controller or load balancer simply doesn't scale as well as a purpose-built load balancing solution because it isn't optimized to be a load balancer and its resource management is limited to that of a typical application server. That's true whether you're using a software solution like Apache mod_proxy_balancer or hardware solution. So if you're implementing this type of a solution to scale an application, you aren't going to see the benefits you think you are, and in fact you may see a degradation of performance due to the introduction of additional hops, additional processing, and poorly designed network architectures. I'm all for load balancing, obviously, but I'm also all for doing it the right way. And these solutions are just not the right way to implement a load balancing solution unless you're trying to learn the concepts involved or are in a computer science class in college. If you're going to do something, do it right. And doing it right means taking into consideration the goals of the solution you're trying to implement. The goals of a load balancing solution are to provide availability and scale, neither of which the solutions presented in this article will truly achieve.
