Search Results

Search found 19002 results on 761 pages for 'oracle b2b 11g practice'.

Page 504/761 | < Previous Page | 500 501 502 503 504 505 506 507 508 509 510 511  | Next Page >

• Exalogic 2.0.1 Tea Break Snippets - Scripting Asset Creation

  - by The Old Toxophilist

  So far in this series we have looked at creating asset within the EMOC BUI but the Exalogic 2.0.1 installation also provide the Iaas cli as an alternative to most of the common functionality available within EMOC. The IaaS cli interface provides access to the functions that are available to a user logged into the BUI with the CloudUser Role. As such not all functionality is available from the command line interface however having said that the IaaS cli provides all the functionality required to create the Assets within a specific Account (Tenure). Because these action are common and repeatable I decided to wrap the functionality within a simple script that takes a simple input file and creates the Asset. Following the Script through will show us the required steps needed to create the various Assets within an Account and hence I will work through the various functions within the script below describing the steps. You will note from the various steps within the script that it is designed to pause between actions allowing the proceeding action to complete. The reason for this is because we could swamp EMOC with a series of actions and may end up with a situation where we are trying to action a Volume attached before the creation of the vServer and Volume have completed. processAssets() This function simply reads through the passed input file identifying what assets need to be created. An example of the input file can be found below. It can be seen that the input file can be used to create Assets in multiple Accounts during a single run. The order of the entries define the functions that need to be actioned as follows: Input Command Iaas Actions Parameters Production:Connect akm-describe-accounts akm-create-access-key iaas-create-key-pair iaas-describe-vnets iaas-describe-vserver-types iaas-describe-server-templates Username Password Production:Create|vServer iaas-run-vserver vServer Name vServer Type Name Template Name Comma separated list of network names which the vServer will connect to. Comma separated list of IPs for the specified networks. Production:Create|Volume iaas-create-volume Volume Name Volume Size Production:Attach|Volume iaas-attach-volumes-to-vserver vServer Name Comma separated list of volume names Production:Disconnect iaas-delete-key-pair akm-delete-access-key None connectToAccount() It can be seen from the connectToAccount function that before we can execute any Asset creation we must first connect to the appropriate account. To do this we will need the ID associated with the Account. This can be found by executing the akm-describe-accounts cli command which will return a list of all Accounts and there IDs. Once we have the Account ID we generate and Access key using the akm-create-access-key command and then a keypair with the iaas-create-key-pair command. At this point we now have all the information we need to access the specific named account. createVServer() This function simply retrieved the information from the input line and then will create the vServer using the iaas-run-vserver cli command. Reading the function you will notice that it takes the various input names for vServer Type, Template and Networks and converts them into the appropriate IDs. The IaaS cli will not work directly with component names and hence all IDs need to be found. createVolume() Function that simply takes the Volume name and Size then executes the iaas-create-volume command to create the volume. attachVolume() Takes the name of the Volume, which we may have just created, and a Volume then identifies the appropriate IDs before assigning the Volume to the vServer with the iaas-attach-volumes-to-vserver. disconnectFromAccount() Once we have finished connecting to the Account we simply remove the key pair with iaas-delete-key-pair and the access key with akm-delete-access-key although it may be useful to keep this if ssh is required and you do not subsequently modify the sshd information to allow unsecured access. By default the key is required for ssh access when a vServer is created from the command-line. CreateAssets.sh 1 export OCCLI=/opt/sun/occli/bin 2 export IAAS_HOME=/opt/oracle/iaas/cli 3 export JAVA_HOME=/usr/java/latest 4 export IAAS_BASE_URL=https://127.0.0.1 5 export IAAS_ACCESS_KEY_FILE=iaas_access.key 6 export KEY_FILE=iaas_access.pub 7 #CloudUser used to create vServers & Volumes 8 export IAAS_USER=exaprod 9 export IAAS_PASSWORD_FILE=root.pwd 10 export KEY_NAME=cli.recreate 11 export INPUT_FILE=CreateAssets.in 12 13 export ACCOUNTS_FILE=accounts.out 14 export VOLUMES_FILE=volumes.out 15 export DISTGRPS_FILE=distgrp.out 16 export VNETS_FILE=vnets.out 17 export VSERVER_TYPES_FILE=vstype.out 18 export VSERVER_FILE=vserver.out 19 export VSERVER_TEMPLATES=template.out 20 export KEY_PAIRS=keypairs.out 21 22 PROCESSING_ACCOUNT="" 23 24 function cleanTempFiles() { 25 rm -f $ACCOUNTS_FILE $VOLUMES_FILE $DISTGRPS_FILE $VNETS_FILE $VSERVER_TYPES_FILE $VSERVER_FILE $VSERVER_TEMPLATES $KEY_PAIRS $IAAS_PASSWORD_FILE $KEY_FILE $IAAS_ACCESS_KEY_FILE 26 } 27 28 function connectToAccount() { 29 if [[ "$ACCOUNT" != "$PROCESSING_ACCOUNT" ]] 30 then 31 if [[ "" != "$PROCESSING_ACCOUNT" ]] 32 then 33 $IAAS_HOME/bin/iaas-delete-key-pair --key-name $KEY_NAME --access-key-file $IAAS_ACCESS_KEY_FILE 34 $IAAS_HOME/bin/akm-delete-access-key $AK 35 fi 36 PROCESSING_ACCOUNT=$ACCOUNT 37 IAAS_USER=$ACCOUNT_USER 38 echo "$ACCOUNT_PASSWORD" > $IAAS_PASSWORD_FILE 39 $IAAS_HOME/bin/akm-describe-accounts --sep "|" > $ACCOUNTS_FILE 40 while read line 41 do 42 ACCOUNT_ID=${line%%|*} 43 line=${line#*|} 44 ACCOUNT_NAME=${line%%|*} 45 # echo "Id = $ACCOUNT_ID" 46 # echo "Name = $ACCOUNT_NAME" 47 if [[ "$ACCOUNT_NAME" == "$ACCOUNT" ]] 48 then 49 echo "Found Production Account $line" 50 AK=`$IAAS_HOME/bin/akm-create-access-key --account $ACCOUNT_ID --access-key-file $IAAS_ACCESS_KEY_FILE` 51 KEYPAIR=`$IAAS_HOME/bin/iaas-create-key-pair --key-name $KEY_NAME --key-file $KEY_FILE` 52 echo "Connected to $ACCOUNT_NAME" 53 break 54 fi 55 done < $ACCOUNTS_FILE 56 fi 57 } 58 59 function disconnectFromAccount() { 60 $IAAS_HOME/bin/iaas-delete-key-pair --key-name $KEY_NAME --access-key-file $IAAS_ACCESS_KEY_FILE 61 $IAAS_HOME/bin/akm-delete-access-key $AK 62 PROCESSING_ACCOUNT="" 63 } 64 65 function getNetworks() { 66 $IAAS_HOME/bin/iaas-describe-vnets --sep "|" > $VNETS_FILE 67 } 68 69 function getVSTypes() { 70 $IAAS_HOME/bin/iaas-describe-vserver-types --sep "|" > $VSERVER_TYPES_FILE 71 } 72 73 function getTemplates() { 74 $IAAS_HOME/bin/iaas-describe-server-templates --sep "|" > $VSERVER_TEMPLATES 75 } 76 77 function getVolumes() { 78 $IAAS_HOME/bin/iaas-describe-volumes --sep "|" > $VOLUMES_FILE 79 } 80 81 function getVServers() { 82 $IAAS_HOME/bin/iaas-describe-vservers --sep "|" > $VSERVER_FILE 83 } 84 85 function getNetworkId() { 86 while read line 87 do 88 NETWORK_ID=${line%%|*} 89 line=${line#*|} 90 NAME=${line%%|*} 91 if [[ "$NAME" == "$NETWORK_NAME" ]] 92 then 93 break 94 fi 95 done < $VNETS_FILE 96 } 97 98 function getVSTypeId() { 99 while read line 100 do 101 VSTYPE_ID=${line%%|*} 102 line=${line#*|} 103 NAME=${line%%|*} 104 if [[ "$VSTYPE_NAME" == "$NAME" ]] 105 then 106 break 107 fi 108 done < $VSERVER_TYPES_FILE 109 } 110 111 function getTemplateId() { 112 while read line 113 do 114 TEMPLATE_ID=${line%%|*} 115 line=${line#*|} 116 NAME=${line%%|*} 117 if [[ "$TEMPLATE_NAME" == "$NAME" ]] 118 then 119 break 120 fi 121 done < $VSERVER_TEMPLATES 122 } 123 124 function getVolumeId() { 125 while read line 126 do 127 export VOLUME_ID=${line%%|*} 128 line=${line#*|} 129 NAME=${line%%|*} 130 if [[ "$NAME" == "$VOLUME_NAME" ]] 131 then 132 break; 133 fi 134 done < $VOLUMES_FILE 135 } 136 137 function getVServerId() { 138 while read line 139 do 140 VSERVER_ID=${line%%|*} 141 line=${line#*|} 142 NAME=${line%%|*} 143 if [[ "$VSERVER_NAME" == "$NAME" ]] 144 then 145 break; 146 fi 147 done < $VSERVER_FILE 148 } 149 150 function getVServerState() { 151 getVServers 152 while read line 153 do 154 VSERVER_ID=${line%%|*} 155 line=${line#*|} 156 NAME=${line%%|*} 157 line=${line#*|} 158 line=${line#*|} 159 VSERVER_STATE=${line%%|*} 160 if [[ "$VSERVER_NAME" == "$NAME" ]] 161 then 162 break; 163 fi 164 done < $VSERVER_FILE 165 } 166 167 function pauseUntilVServerRunning() { 168 # Wait until the Server is running before creating the next 169 getVServerState 170 while [[ "$VSERVER_STATE" != "RUNNING" ]] 171 do 172 getVServerState 173 echo "$NAME $VSERVER_STATE" 174 if [[ "$VSERVER_STATE" != "RUNNING" ]] 175 then 176 echo "Sleeping......." 177 sleep 60 178 fi 179 if [[ "$VSERVER_STATE" == "FAILED" ]] 180 then 181 echo "Will Delete $NAME in 5 Minutes....." 182 sleep 300 183 deleteVServer 184 echo "Deleted $NAME waiting 5 Minutes....." 185 sleep 300 186 break 187 fi 188 done 189 # Lets pause for a minute or two 190 echo "Just Chilling......" 191 sleep 60 192 echo "Ahhhhh we're getting there......." 193 sleep 60 194 echo "I'm almost at one with the universe......." 195 sleep 60 196 echo "Bong Reality Check !" 197 } 198 199 function deleteVServer() { 200 $IAAS_HOME/bin/iaas-terminate-vservers --force --vserver-ids $VSERVER_ID 201 } 202 203 function createVServer() { 204 VSERVER_NAME=${ASSET_DETAILS%%|*} 205 ASSET_DETAILS=${ASSET_DETAILS#*|} 206 VSTYPE_NAME=${ASSET_DETAILS%%|*} 207 ASSET_DETAILS=${ASSET_DETAILS#*|} 208 TEMPLATE_NAME=${ASSET_DETAILS%%|*} 209 ASSET_DETAILS=${ASSET_DETAILS#*|} 210 NETWORK_NAMES=${ASSET_DETAILS%%|*} 211 ASSET_DETAILS=${ASSET_DETAILS#*|} 212 IP_ADDRESSES=${ASSET_DETAILS%%|*} 213 # Get Ids associated with names 214 getVSTypeId 215 getTemplateId 216 # Convert Network Names to Ids 217 NETWORK_IDS="" 218 while true 219 do 220 NETWORK_NAME=${NETWORK_NAMES%%,*} 221 NETWORK_NAMES=${NETWORK_NAMES#*,} 222 getNetworkId 223 if [[ "$NETWORK_IDS" != "" ]] 224 then 225 NETWORK_IDS="$NETWORK_IDS,$NETWORK_ID" 226 else 227 NETWORK_IDS=$NETWORK_ID 228 fi 229 if [[ "$NETWORK_NAME" == "$NETWORK_NAMES" ]] 230 then 231 break 232 fi 233 done 234 # Create vServer 235 echo "About to execute : $IAAS_HOME/bin/iaas-run-vserver --name $VSERVER_NAME --key-name $KEY_NAME --vserver-type $VSTYPE_ID --server-template-id $TEMPLATE_ID --vnets $NETWORK_IDS --ip-addresses $IP_ADDRESSES" 236 $IAAS_HOME/bin/iaas-run-vserver --name $VSERVER_NAME --key-name $KEY_NAME --vserver-type $VSTYPE_ID --server-template-id $TEMPLATE_ID --vnets $NETWORK_IDS --ip-addresses $IP_ADDRESSES 237 pauseUntilVServerRunning 238 } 239 240 function createVolume() { 241 VOLUME_NAME=${ASSET_DETAILS%%|*} 242 ASSET_DETAILS=${ASSET_DETAILS#*|} 243 VOLUME_SIZE=${ASSET_DETAILS%%|*} 244 # Create Volume 245 echo "About to execute : $IAAS_HOME/bin/iaas-create-volume --name $VOLUME_NAME --size $VOLUME_SIZE" 246 $IAAS_HOME/bin/iaas-create-volume --name $VOLUME_NAME --size $VOLUME_SIZE 247 # Lets pause 248 echo "Just Waiting 30 Seconds......" 249 sleep 30 250 } 251 252 function attachVolume() { 253 VSERVER_NAME=${ASSET_DETAILS%%|*} 254 ASSET_DETAILS=${ASSET_DETAILS#*|} 255 VOLUME_NAMES=${ASSET_DETAILS%%|*} 256 # Get vServer Id 257 getVServerId 258 # Convert Volume Names to Ids 259 VOLUME_IDS="" 260 while true 261 do 262 VOLUME_NAME=${VOLUME_NAMES%%,*} 263 VOLUME_NAMES=${VOLUME_NAMES#*,} 264 getVolumeId 265 if [[ "$VOLUME_IDS" != "" ]] 266 then 267 VOLUME_IDS="$VOLUME_IDS,$VOLUME_ID" 268 else 269 VOLUME_IDS=$VOLUME_ID 270 fi 271 if [[ "$VOLUME_NAME" == "$VOLUME_NAMES" ]] 272 then 273 break 274 fi 275 done 276 # Attach Volumes 277 echo "About to execute : $IAAS_HOME/bin/iaas-attach-volumes-to-vserver --vserver-id $VSERVER_ID --volume-ids $VOLUME_IDS" 278 $IAAS_HOME/bin/iaas-attach-volumes-to-vserver --vserver-id $VSERVER_ID --volume-ids $VOLUME_IDS 279 # Lets pause 280 echo "Just Waiting 30 Seconds......" 281 sleep 30 282 } 283 284 function processAssets() { 285 while read line 286 do 287 ACCOUNT=${line%%:*} 288 line=${line#*:} 289 ACTION=${line%%|*} 290 line=${line#*|} 291 if [[ "$ACTION" == "Connect" ]] 292 then 293 ACCOUNT_USER=${line%%|*} 294 line=${line#*|} 295 ACCOUNT_PASSWORD=${line%%|*} 296 connectToAccount 297 298 ## Account Info 299 getNetworks 300 getVSTypes 301 getTemplates 302 303 continue 304 fi 305 if [[ "$ACTION" == "Create" ]] 306 then 307 ASSET=${line%%|*} 308 line=${line#*|} 309 ASSET_DETAILS=$line 310 if [[ "$ASSET" == "vServer" ]] 311 then 312 createVServer 313 314 continue 315 fi 316 if [[ "$ASSET" == "Volume" ]] 317 then 318 createVolume 319 320 continue 321 fi 322 fi 323 if [[ "$ACTION" == "Attach" ]] 324 then 325 ASSET=${line%%|*} 326 line=${line#*|} 327 ASSET_DETAILS=$line 328 if [[ "$ASSET" == "Volume" ]] 329 then 330 getVolumes 331 getVServers 332 attachVolume 333 334 continue 335 fi 336 fi 337 if [[ "$ACTION" == "Connect" ]] 338 then 339 disconnectFromAccount 340 341 continue 342 fi 343 done < $INPUT_FILE 344 } 345 346 # Should Parameterise this 347 348 while [ $# -gt 0 ] 349 do 350 case "$1" in 351 -a) INPUT_FILE="$2"; shift;; 352 *) echo ""; echo >&2 \ 353 "usage: $0 [-a <Asset Definition File>] (Default is CreateAssets.in)" 354 echo""; exit 1;; 355 *) break;; 356 esac 357 shift 358 done 359 360 361 362 363 processAssets 364 365 echo "**************************************" 366 echo "***** Finished Creating Assets *****" 367 echo "**************************************" 368 CreateAssetsProd.in Production:Connect|exaprod|welcome1 Production:Create|vServer|VS006|VSTProduction|BaseOEL56ServerTemplate|EoIB-otd-prod,vn-prod-web,IPoIB-default,IPoIB-vserver-shared-storage|10.51.223.13,192.168.0.13,10.117.81.67,172.17.0.14 Production:Create|vServer|VS007|VSTProduction|BaseOEL56ServerTemplate|EoIB-otd-prod,vn-prod-web,IPoIB-default,IPoIB-vserver-shared-storage|10.51.223.14,192.168.0.14,10.117.81.68,172.17.0.15 Production:Create|vServer|VS008|VSTProduction|BaseOEL56ServerTemplate|EoIB-wls-prod,vn-prod-web,IPoIB-default,IPoIB-vserver-shared-storage|10.51.225.61,192.168.0.61,10.117.81.61,172.17.0.16 Production:Create|vServer|VS009|VSTProduction|BaseOEL56ServerTemplate|EoIB-wls-prod,vn-prod-web,IPoIB-default,IPoIB-vserver-shared-storage|10.51.225.62,192.168.0.62,10.117.81.62,172.17.0.17 Production:Create|vServer|VS000|VSTProduction|BaseOEL56ServerTemplate|EoIB-wls-prod,vn-prod-web,IPoIB-default,IPoIB-vserver-shared-storage|10.51.225.63,192.168.0.63,10.117.81.63,172.17.0.18 Production:Create|vServer|VS001|VSTProduction|BaseOEL56ServerTemplate|EoIB-wls-prod,vn-prod-web,IPoIB-default,IPoIB-vserver-shared-storage|10.51.225.64,192.168.0.64,10.117.81.64,172.17.0.19 Production:Create|vServer|VS002|VSTProduction|BaseOEL56ServerTemplate|EoIB-wls-prod,vn-prod-web,IPoIB-default,IPoIB-vserver-shared-storage|10.51.225.65,192.168.0.65,10.117.81.65,172.17.0.20 Production:Create|vServer|VS003|VSTProduction|BaseOEL56ServerTemplate|EoIB-wls-prod,vn-prod-web,IPoIB-default,IPoIB-vserver-shared-storage|10.51.225.66,192.168.0.66,10.117.81.66,172.17.0.21 Production:Create|Volume|VS006|50 Production:Create|Volume|VS007|50 Production:Create|Volume|VS008|50 Production:Create|Volume|VS009|50 Production:Create|Volume|VS000|50 Production:Create|Volume|VS001|50 Production:Create|Volume|VS002|50 Production:Create|Volume|VS003|50 Production:Attach|Volume|VS006|VS006 Production:Attach|Volume|VS007|VS007 Production:Attach|Volume|VS008|VS008 Production:Attach|Volume|VS009|VS009 Production:Attach|Volume|VS000|VS000 Production:Attach|Volume|VS001|VS001 Production:Attach|Volume|VS002|VS002 Production:Attach|Volume|VS003|VS003 Production:Disconnect Development:Connect|exadev|welcome1 Development:Create|vServer|VS014|VSTDevelopment|BaseOEL56ServerTemplate|EoIB-development,IPoIB-default,IPoIB-vserver-shared-storage|10.51.224.24,10.117.81.71,172.17.0.24 Development:Create|vServer|VS015|VSTDevelopment|BaseOEL56ServerTemplate|EoIB-development,IPoIB-default,IPoIB-vserver-shared-storage|10.51.224.25,10.117.81.72,172.17.0.25 Development:Create|vServer|VS016|VSTDevelopment|BaseOEL56ServerTemplate|EoIB-development,IPoIB-default,IPoIB-vserver-shared-storage|10.51.224.26,10.117.81.73,172.17.0.26 Development:Create|vServer|VS017|VSTDevelopment|BaseOEL56ServerTemplate|EoIB-development,IPoIB-default,IPoIB-vserver-shared-storage|10.51.224.27,10.117.81.74,172.17.0.27 Development:Create|vServer|VS018|VSTDevelopment|BaseOEL56ServerTemplate|EoIB-development,IPoIB-default,IPoIB-vserver-shared-storage|10.51.224.28,10.117.81.75,172.17.0.28 Development:Create|vServer|VS019|VSTDevelopment|BaseOEL56ServerTemplate|EoIB-development,IPoIB-default,IPoIB-vserver-shared-storage|10.51.224.29,10.117.81.76,172.17.0.29 Development:Create|vServer|VS020|VSTDevelopment|BaseOEL56ServerTemplate|EoIB-development,IPoIB-default,IPoIB-vserver-shared-storage|10.51.224.30,10.117.81.77,172.17.0.30 Development:Create|vServer|VS021|VSTDevelopment|BaseOEL56ServerTemplate|EoIB-development,IPoIB-default,IPoIB-vserver-shared-storage|10.51.224.31,10.117.81.78,172.17.0.31 Development:Create|vServer|VS022|VSTDevelopment|BaseOEL56ServerTemplate|EoIB-development,IPoIB-default,IPoIB-vserver-shared-storage|10.51.224.32,10.117.81.79,172.17.0.32 Development:Create|vServer|VS023|VSTDevelopment|BaseOEL56ServerTemplate|EoIB-development,IPoIB-default,IPoIB-vserver-shared-storage|10.51.224.33,10.117.81.80,172.17.0.33 Development:Create|vServer|VS024|VSTDevelopment|BaseOEL56ServerTemplate|EoIB-development,IPoIB-default,IPoIB-vserver-shared-storage|10.51.224.34,10.117.81.81,172.17.0.34 Development:Create|vServer|VS025|VSTDevelopment|BaseOEL56ServerTemplate|EoIB-development,IPoIB-default,IPoIB-vserver-shared-storage|10.51.224.35,10.117.81.82,172.17.0.35 Development:Create|vServer|VS026|VSTDevelopment|BaseOEL56ServerTemplate|EoIB-development,IPoIB-default,IPoIB-vserver-shared-storage|10.51.224.36,10.117.81.83,172.17.0.36 Development:Create|vServer|VS027|VSTDevelopment|BaseOEL56ServerTemplate|EoIB-development,IPoIB-default,IPoIB-vserver-shared-storage|10.51.224.37,10.117.81.84,172.17.0.37 Development:Create|Volume|VS014|50 Development:Create|Volume|VS015|50 Development:Create|Volume|VS016|50 Development:Create|Volume|VS017|50 Development:Create|Volume|VS018|50 Development:Create|Volume|VS019|50 Development:Create|Volume|VS020|50 Development:Create|Volume|VS021|50 Development:Create|Volume|VS022|50 Development:Create|Volume|VS023|50 Development:Create|Volume|VS024|50 Development:Create|Volume|VS025|50 Development:Create|Volume|VS026|50 Development:Create|Volume|VS027|50 Development:Attach|Volume|VS014|VS014 Development:Attach|Volume|VS015|VS015 Development:Attach|Volume|VS016|VS016 Development:Attach|Volume|VS017|VS017 Development:Attach|Volume|VS018|VS018 Development:Attach|Volume|VS019|VS019 Development:Attach|Volume|VS020|VS020 Development:Attach|Volume|VS021|VS021 Development:Attach|Volume|VS022|VS022 Development:Attach|Volume|VS023|VS023 Development:Attach|Volume|VS024|VS024 Development:Attach|Volume|VS025|VS025 Development:Attach|Volume|VS026|VS026 Development:Attach|Volume|VS027|VS027 Development:Disconnect This entry was originally posted on the The Old Toxophilist Site.

  Read the article

• Top 10 Reasons Not To Do a Semantic Web Project

  A startup's goal is success via the most simple and fastest route, and the Semantic Web rarely offers that in practice.

  Read the article

• Top 10 Reasons Not To Do a Semantic Web Project

  A startup's goal is success via the most simple and fastest route, and the Semantic Web rarely offers that in practice.

  Read the article

• value types in the vm

  - by john.rose

  value types in the vm p.p1 {margin: 0.0px 0.0px 0.0px 0.0px; font: 14.0px Times} p.p2 {margin: 0.0px 0.0px 14.0px 0.0px; font: 14.0px Times} p.p3 {margin: 0.0px 0.0px 12.0px 0.0px; font: 14.0px Times} p.p4 {margin: 0.0px 0.0px 15.0px 0.0px; font: 14.0px Times} p.p5 {margin: 0.0px 0.0px 0.0px 0.0px; font: 14.0px Courier} p.p6 {margin: 0.0px 0.0px 0.0px 0.0px; font: 14.0px Courier; min-height: 17.0px} p.p7 {margin: 0.0px 0.0px 0.0px 0.0px; font: 14.0px Times; min-height: 18.0px} p.p8 {margin: 0.0px 0.0px 0.0px 36.0px; text-indent: -36.0px; font: 14.0px Times; min-height: 18.0px} p.p9 {margin: 0.0px 0.0px 12.0px 0.0px; font: 14.0px Times; min-height: 18.0px} p.p10 {margin: 0.0px 0.0px 12.0px 0.0px; font: 14.0px Times; color: #000000} li.li1 {margin: 0.0px 0.0px 0.0px 0.0px; font: 14.0px Times} li.li7 {margin: 0.0px 0.0px 0.0px 0.0px; font: 14.0px Times; min-height: 18.0px} span.s1 {font: 14.0px Courier} span.s2 {color: #000000} span.s3 {font: 14.0px Courier; color: #000000} ol.ol1 {list-style-type: decimal} Or, enduring values for a changing world. Introduction A value type is a data type which, generally speaking, is designed for being passed by value in and out of methods, and stored by value in data structures. The only value types which the Java language directly supports are the eight primitive types. Java indirectly and approximately supports value types, if they are implemented in terms of classes. For example, both Integer and String may be viewed as value types, especially if their usage is restricted to avoid operations appropriate to Object. In this note, we propose a definition of value types in terms of a design pattern for Java classes, accompanied by a set of usage restrictions. We also sketch the relation of such value types to tuple types (which are a JVM-level notion), and point out JVM optimizations that can apply to value types. This note is a thought experiment to extend the JVM’s performance model in support of value types. The demonstration has two phases.  Initially the extension can simply use design patterns, within the current bytecode architecture, and in today’s Java language. But if the performance model is to be realized in practice, it will probably require new JVM bytecode features, changes to the Java language, or both.  We will look at a few possibilities for these new features. An Axiom of Value In the context of the JVM, a value type is a data type equipped with construction, assignment, and equality operations, and a set of typed components, such that, whenever two variables of the value type produce equal corresponding values for their components, the values of the two variables cannot be distinguished by any JVM operation. Here are some corollaries: A value type is immutable, since otherwise a copy could be constructed and the original could be modified in one of its components, allowing the copies to be distinguished. Changing the component of a value type requires construction of a new value. The equals and hashCode operations are strictly component-wise. If a value type is represented by a JVM reference, that reference cannot be successfully synchronized on, and cannot be usefully compared for reference equality. A value type can be viewed in terms of what it doesn’t do. We can say that a value type omits all value-unsafe operations, which could violate the constraints on value types.  These operations, which are ordinarily allowed for Java object types, are pointer equality comparison (the acmp instruction), synchronization (the monitor instructions), all the wait and notify methods of class Object, and non-trivial finalize methods. The clone method is also value-unsafe, although for value types it could be treated as the identity function. Finally, and most importantly, any side effect on an object (however visible) also counts as an value-unsafe operation. A value type may have methods, but such methods must not change the components of the value. It is reasonable and useful to define methods like toString, equals, and hashCode on value types, and also methods which are specifically valuable to users of the value type. Representations of Value Value types have two natural representations in the JVM, unboxed and boxed. An unboxed value consists of the components, as simple variables. For example, the complex number x=(1+2i), in rectangular coordinate form, may be represented in unboxed form by the following pair of variables: /*Complex x = Complex.valueOf(1.0, 2.0):*/ double x_re = 1.0, x_im = 2.0; These variables might be locals, parameters, or fields. Their association as components of a single value is not defined to the JVM. Here is a sample computation which computes the norm of the difference between two complex numbers: double distance(/*Complex x:*/ double x_re, double x_im,         /*Complex y:*/ double y_re, double y_im) {     /*Complex z = x.minus(y):*/     double z_re = x_re - y_re, z_im = x_im - y_im;     /*return z.abs():*/     return Math.sqrt(z_re*z_re + z_im*z_im); } A boxed representation groups component values under a single object reference. The reference is to a ‘wrapper class’ that carries the component values in its fields. (A primitive type can naturally be equated with a trivial value type with just one component of that type. In that view, the wrapper class Integer can serve as a boxed representation of value type int.) The unboxed representation of complex numbers is practical for many uses, but it fails to cover several major use cases: return values, array elements, and generic APIs. The two components of a complex number cannot be directly returned from a Java function, since Java does not support multiple return values. The same story applies to array elements: Java has no ’array of structs’ feature. (Double-length arrays are a possible workaround for complex numbers, but not for value types with heterogeneous components.) By generic APIs I mean both those which use generic types, like Arrays.asList and those which have special case support for primitive types, like String.valueOf and PrintStream.println. Those APIs do not support unboxed values, and offer some problems to boxed values. Any ’real’ JVM type should have a story for returns, arrays, and API interoperability. The basic problem here is that value types fall between primitive types and object types. Value types are clearly more complex than primitive types, and object types are slightly too complicated. Objects are a little bit dangerous to use as value carriers, since object references can be compared for pointer equality, and can be synchronized on. Also, as many Java programmers have observed, there is often a performance cost to using wrapper objects, even on modern JVMs. Even so, wrapper classes are a good starting point for talking about value types. If there were a set of structural rules and restrictions which would prevent value-unsafe operations on value types, wrapper classes would provide a good notation for defining value types. This note attempts to define such rules and restrictions. Let’s Start Coding Now it is time to look at some real code. Here is a definition, written in Java, of a complex number value type. @ValueSafe public final class Complex implements java.io.Serializable {     // immutable component structure:     public final double re, im;     private Complex(double re, double im) {         this.re = re; this.im = im;     }     // interoperability methods:     public String toString() { return "Complex("+re+","+im+")"; }     public List<Double> asList() { return Arrays.asList(re, im); }     public boolean equals(Complex c) {         return re == c.re && im == c.im;     }     public boolean equals(@ValueSafe Object x) {         return x instanceof Complex && equals((Complex) x);     }     public int hashCode() {         return 31*Double.valueOf(re).hashCode()                 + Double.valueOf(im).hashCode();     }     // factory methods:     public static Complex valueOf(double re, double im) {         return new Complex(re, im);     }     public Complex changeRe(double re2) { return valueOf(re2, im); }     public Complex changeIm(double im2) { return valueOf(re, im2); }     public static Complex cast(@ValueSafe Object x) {         return x == null ? ZERO : (Complex) x;     }     // utility methods and constants:     public Complex plus(Complex c)  { return new Complex(re+c.re, im+c.im); }     public Complex minus(Complex c) { return new Complex(re-c.re, im-c.im); }     public double abs() { return Math.sqrt(re*re + im*im); }     public static final Complex PI = valueOf(Math.PI, 0.0);     public static final Complex ZERO = valueOf(0.0, 0.0); } This is not a minimal definition, because it includes some utility methods and other optional parts.  The essential elements are as follows: The class is marked as a value type with an annotation. The class is final, because it does not make sense to create subclasses of value types. The fields of the class are all non-private and final.  (I.e., the type is immutable and structurally transparent.) From the supertype Object, all public non-final methods are overridden. The constructor is private. Beyond these bare essentials, we can observe the following features in this example, which are likely to be typical of all value types: One or more factory methods are responsible for value creation, including a component-wise valueOf method. There are utility methods for complex arithmetic and instance creation, such as plus and changeIm. There are static utility constants, such as PI. The type is serializable, using the default mechanisms. There are methods for converting to and from dynamically typed references, such as asList and cast. The Rules In order to use value types properly, the programmer must avoid value-unsafe operations.  A helpful Java compiler should issue errors (or at least warnings) for code which provably applies value-unsafe operations, and should issue warnings for code which might be correct but does not provably avoid value-unsafe operations.  No such compilers exist today, but to simplify our account here, we will pretend that they do exist. A value-safe type is any class, interface, or type parameter marked with the @ValueSafe annotation, or any subtype of a value-safe type.  If a value-safe class is marked final, it is in fact a value type.  All other value-safe classes must be abstract.  The non-static fields of a value class must be non-public and final, and all its constructors must be private. Under the above rules, a standard interface could be helpful to define value types like Complex.  Here is an example: @ValueSafe public interface ValueType extends java.io.Serializable {     // All methods listed here must get redefined.     // Definitions must be value-safe, which means     // they may depend on component values only.     List<? extends Object> asList();     int hashCode();     boolean equals(@ValueSafe Object c);     String toString(); } //@ValueSafe inherited from supertype: public final class Complex implements ValueType { … The main advantage of such a conventional interface is that (unlike an annotation) it is reified in the runtime type system.  It could appear as an element type or parameter bound, for facilities which are designed to work on value types only.  More broadly, it might assist the JVM to perform dynamic enforcement of the rules for value types. Besides types, the annotation @ValueSafe can mark fields, parameters, local variables, and methods.  (This is redundant when the type is also value-safe, but may be useful when the type is Object or another supertype of a value type.)  Working forward from these annotations, an expression E is defined as value-safe if it satisfies one or more of the following: The type of E is a value-safe type. E names a field, parameter, or local variable whose declaration is marked @ValueSafe. E is a call to a method whose declaration is marked @ValueSafe. E is an assignment to a value-safe variable, field reference, or array reference. E is a cast to a value-safe type from a value-safe expression. E is a conditional expression E0 ? E1 : E2, and both E1 and E2 are value-safe. Assignments to value-safe expressions and initializations of value-safe names must take their values from value-safe expressions. A value-safe expression may not be the subject of a value-unsafe operation.  In particular, it cannot be synchronized on, nor can it be compared with the “==” operator, not even with a null or with another value-safe type. In a program where all of these rules are followed, no value-type value will be subject to a value-unsafe operation.  Thus, the prime axiom of value types will be satisfied, that no two value type will be distinguishable as long as their component values are equal. More Code To illustrate these rules, here are some usage examples for Complex: Complex pi = Complex.valueOf(Math.PI, 0); Complex zero = pi.changeRe(0);  //zero = pi; zero.re = 0; ValueType vtype = pi; @SuppressWarnings("value-unsafe")   Object obj = pi; @ValueSafe Object obj2 = pi; obj2 = new Object();  // ok List<Complex> clist = new ArrayList<Complex>(); clist.add(pi);  // (ok assuming List.add param is @ValueSafe) List<ValueType> vlist = new ArrayList<ValueType>(); vlist.add(pi);  // (ok) List<Object> olist = new ArrayList<Object>(); olist.add(pi);  // warning: "value-unsafe" boolean z = pi.equals(zero); boolean z1 = (pi == zero);  // error: reference comparison on value type boolean z2 = (pi == null);  // error: reference comparison on value type boolean z3 = (pi == obj2);  // error: reference comparison on value type synchronized (pi) { }  // error: synch of value, unpredictable result synchronized (obj2) { }  // unpredictable result Complex qq = pi; qq = null;  // possible NPE; warning: “null-unsafe" qq = (Complex) obj;  // warning: “null-unsafe" qq = Complex.cast(obj);  // OK @SuppressWarnings("null-unsafe")   Complex empty = null;  // possible NPE qq = empty;  // possible NPE (null pollution) The Payoffs It follows from this that either the JVM or the java compiler can replace boxed value-type values with unboxed ones, without affecting normal computations.  Fields and variables of value types can be split into their unboxed components.  Non-static methods on value types can be transformed into static methods which take the components as value parameters. Some common questions arise around this point in any discussion of value types. Why burden the programmer with all these extra rules?  Why not detect programs automagically and perform unboxing transparently?  The answer is that it is easy to break the rules accidently unless they are agreed to by the programmer and enforced.  Automatic unboxing optimizations are tantalizing but (so far) unreachable ideal.  In the current state of the art, it is possible exhibit benchmarks in which automatic unboxing provides the desired effects, but it is not possible to provide a JVM with a performance model that assures the programmer when unboxing will occur.  This is why I’m writing this note, to enlist help from, and provide assurances to, the programmer.  Basically, I’m shooting for a good set of user-supplied “pragmas” to frame the desired optimization. Again, the important thing is that the unboxing must be done reliably, or else programmers will have no reason to work with the extra complexity of the value-safety rules.  There must be a reasonably stable performance model, wherein using a value type has approximately the same performance characteristics as writing the unboxed components as separate Java variables. There are some rough corners to the present scheme.  Since Java fields and array elements are initialized to null, value-type computations which incorporate uninitialized variables can produce null pointer exceptions.  One workaround for this is to require such variables to be null-tested, and the result replaced with a suitable all-zero value of the value type.  That is what the “cast” method does above. Generically typed APIs like List<T> will continue to manipulate boxed values always, at least until we figure out how to do reification of generic type instances.  Use of such APIs will elicit warnings until their type parameters (and/or relevant members) are annotated or typed as value-safe.  Retrofitting List<T> is likely to expose flaws in the present scheme, which we will need to engineer around.  Here are a couple of first approaches: public interface java.util.List<@ValueSafe T> extends Collection<T> { … public interface java.util.List<T extends Object|ValueType> extends Collection<T> { … (The second approach would require disjunctive types, in which value-safety is “contagious” from the constituent types.) With more transformations, the return value types of methods can also be unboxed.  This may require significant bytecode-level transformations, and would work best in the presence of a bytecode representation for multiple value groups, which I have proposed elsewhere under the title “Tuples in the VM”. But for starters, the JVM can apply this transformation under the covers, to internally compiled methods.  This would give a way to express multiple return values and structured return values, which is a significant pain-point for Java programmers, especially those who work with low-level structure types favored by modern vector and graphics processors.  The lack of multiple return values has a strong distorting effect on many Java APIs. Even if the JVM fails to unbox a value, there is still potential benefit to the value type.  Clustered computing systems something have copy operations (serialization or something similar) which apply implicitly to command operands.  When copying JVM objects, it is extremely helpful to know when an object’s identity is important or not.  If an object reference is a copied operand, the system may have to create a proxy handle which points back to the original object, so that side effects are visible.  Proxies must be managed carefully, and this can be expensive.  On the other hand, value types are exactly those types which a JVM can “copy and forget” with no downside. Array types are crucial to bulk data interfaces.  (As data sizes and rates increase, bulk data becomes more important than scalar data, so arrays are definitely accompanying us into the future of computing.)  Value types are very helpful for adding structure to bulk data, so a successful value type mechanism will make it easier for us to express richer forms of bulk data. Unboxing arrays (i.e., arrays containing unboxed values) will provide better cache and memory density, and more direct data movement within clustered or heterogeneous computing systems.  They require the deepest transformations, relative to today’s JVM.  There is an impedance mismatch between value-type arrays and Java’s covariant array typing, so compromises will need to be struck with existing Java semantics.  It is probably worth the effort, since arrays of unboxed value types are inherently more memory-efficient than standard Java arrays, which rely on dependent pointer chains. It may be sufficient to extend the “value-safe” concept to array declarations, and allow low-level transformations to change value-safe array declarations from the standard boxed form into an unboxed tuple-based form.  Such value-safe arrays would not be convertible to Object[] arrays.  Certain connection points, such as Arrays.copyOf and System.arraycopy might need additional input/output combinations, to allow smooth conversion between arrays with boxed and unboxed elements. Alternatively, the correct solution may have to wait until we have enough reification of generic types, and enough operator overloading, to enable an overhaul of Java arrays. Implicit Method Definitions The example of class Complex above may be unattractively complex.  I believe most or all of the elements of the example class are required by the logic of value types. If this is true, a programmer who writes a value type will have to write lots of error-prone boilerplate code.  On the other hand, I think nearly all of the code (except for the domain-specific parts like plus and minus) can be implicitly generated. Java has a rule for implicitly defining a class’s constructor, if no it defines no constructors explicitly.  Likewise, there are rules for providing default access modifiers for interface members.  Because of the highly regular structure of value types, it might be reasonable to perform similar implicit transformations on value types.  Here’s an example of a “highly implicit” definition of a complex number type: public class Complex implements ValueType {  // implicitly final     public double re, im;  // implicitly public final     //implicit methods are defined elementwise from te fields:     //  toString, asList, equals(2), hashCode, valueOf, cast     //optionally, explicit methods (plus, abs, etc.) would go here } In other words, with the right defaults, a simple value type definition can be a one-liner.  The observant reader will have noticed the similarities (and suitable differences) between the explicit methods above and the corresponding methods for List<T>. Another way to abbreviate such a class would be to make an annotation the primary trigger of the functionality, and to add the interface(s) implicitly: public @ValueType class Complex { … // implicitly final, implements ValueType (But to me it seems better to communicate the “magic” via an interface, even if it is rooted in an annotation.) Implicitly Defined Value Types So far we have been working with nominal value types, which is to say that the sequence of typed components is associated with a name and additional methods that convey the intention of the programmer.  A simple ordered pair of floating point numbers can be variously interpreted as (to name a few possibilities) a rectangular or polar complex number or Cartesian point.  The name and the methods convey the intended meaning. But what if we need a truly simple ordered pair of floating point numbers, without any further conceptual baggage?  Perhaps we are writing a method (like “divideAndRemainder”) which naturally returns a pair of numbers instead of a single number.  Wrapping the pair of numbers in a nominal type (like “QuotientAndRemainder”) makes as little sense as wrapping a single return value in a nominal type (like “Quotient”).  What we need here are structural value types commonly known as tuples. For the present discussion, let us assign a conventional, JVM-friendly name to tuples, roughly as follows: public class java.lang.tuple.$DD extends java.lang.tuple.Tuple {      double $1, $2; } Here the component names are fixed and all the required methods are defined implicitly.  The supertype is an abstract class which has suitable shared declarations.  The name itself mentions a JVM-style method parameter descriptor, which may be “cracked” to determine the number and types of the component fields. The odd thing about such a tuple type (and structural types in general) is it must be instantiated lazily, in response to linkage requests from one or more classes that need it.  The JVM and/or its class loaders must be prepared to spin a tuple type on demand, given a simple name reference, $xyz, where the xyz is cracked into a series of component types.  (Specifics of naming and name mangling need some tasteful engineering.) Tuples also seem to demand, even more than nominal types, some support from the language.  (This is probably because notations for non-nominal types work best as combinations of punctuation and type names, rather than named constructors like Function3 or Tuple2.)  At a minimum, languages with tuples usually (I think) have some sort of simple bracket notation for creating tuples, and a corresponding pattern-matching syntax (or “destructuring bind”) for taking tuples apart, at least when they are parameter lists.  Designing such a syntax is no simple thing, because it ought to play well with nominal value types, and also with pre-existing Java features, such as method parameter lists, implicit conversions, generic types, and reflection.  That is a task for another day. Other Use Cases Besides complex numbers and simple tuples there are many use cases for value types.  Many tuple-like types have natural value-type representations. These include rational numbers, point locations and pixel colors, and various kinds of dates and addresses. Other types have a variable-length ‘tail’ of internal values. The most common example of this is String, which is (mathematically) a sequence of UTF-16 character values. Similarly, bit vectors, multiple-precision numbers, and polynomials are composed of sequences of values. Such types include, in their representation, a reference to a variable-sized data structure (often an array) which (somehow) represents the sequence of values. The value type may also include ’header’ information. Variable-sized values often have a length distribution which favors short lengths. In that case, the design of the value type can make the first few values in the sequence be direct ’header’ fields of the value type. In the common case where the header is enough to represent the whole value, the tail can be a shared null value, or even just a null reference. Note that the tail need not be an immutable object, as long as the header type encapsulates it well enough. This is the case with String, where the tail is a mutable (but never mutated) character array. Field types and their order must be a globally visible part of the API.  The structure of the value type must be transparent enough to have a globally consistent unboxed representation, so that all callers and callees agree about the type and order of components  that appear as parameters, return types, and array elements.  This is a trade-off between efficiency and encapsulation, which is forced on us when we remove an indirection enjoyed by boxed representations.  A JVM-only transformation would not care about such visibility, but a bytecode transformation would need to take care that (say) the components of complex numbers would not get swapped after a redefinition of Complex and a partial recompile.  Perhaps constant pool references to value types need to declare the field order as assumed by each API user. This brings up the delicate status of private fields in a value type.  It must always be possible to load, store, and copy value types as coordinated groups, and the JVM performs those movements by moving individual scalar values between locals and stack.  If a component field is not public, what is to prevent hostile code from plucking it out of the tuple using a rogue aload or astore instruction?  Nothing but the verifier, so we may need to give it more smarts, so that it treats value types as inseparable groups of stack slots or locals (something like long or double). My initial thought was to make the fields always public, which would make the security problem moot.  But public is not always the right answer; consider the case of String, where the underlying mutable character array must be encapsulated to prevent security holes.  I believe we can win back both sides of the tradeoff, by training the verifier never to split up the components in an unboxed value.  Just as the verifier encapsulates the two halves of a 64-bit primitive, it can encapsulate the the header and body of an unboxed String, so that no code other than that of class String itself can take apart the values. Similar to String, we could build an efficient multi-precision decimal type along these lines: public final class DecimalValue extends ValueType {     protected final long header;     protected private final BigInteger digits;     public DecimalValue valueOf(int value, int scale) {         assert(scale >= 0);         return new DecimalValue(((long)value << 32) + scale, null);     }     public DecimalValue valueOf(long value, int scale) {         if (value == (int) value)             return valueOf((int)value, scale);         return new DecimalValue(-scale, new BigInteger(value));     } } Values of this type would be passed between methods as two machine words. Small values (those with a significand which fits into 32 bits) would be represented without any heap data at all, unless the DecimalValue itself were boxed. (Note the tension between encapsulation and unboxing in this case.  It would be better if the header and digits fields were private, but depending on where the unboxing information must “leak”, it is probably safer to make a public revelation of the internal structure.) Note that, although an array of Complex can be faked with a double-length array of double, there is no easy way to fake an array of unboxed DecimalValues.  (Either an array of boxed values or a transposed pair of homogeneous arrays would be reasonable fallbacks, in a current JVM.)  Getting the full benefit of unboxing and arrays will require some new JVM magic. Although the JVM emphasizes portability, system dependent code will benefit from using machine-level types larger than 64 bits.  For example, the back end of a linear algebra package might benefit from value types like Float4 which map to stock vector types.  This is probably only worthwhile if the unboxing arrays can be packed with such values. More Daydreams A more finely-divided design for dynamic enforcement of value safety could feature separate marker interfaces for each invariant.  An empty marker interface Unsynchronizable could cause suitable exceptions for monitor instructions on objects in marked classes.  More radically, a Interchangeable marker interface could cause JVM primitives that are sensitive to object identity to raise exceptions; the strangest result would be that the acmp instruction would have to be specified as raising an exception. @ValueSafe public interface ValueType extends java.io.Serializable,         Unsynchronizable, Interchangeable { … public class Complex implements ValueType {     // inherits Serializable, Unsynchronizable, Interchangeable, @ValueSafe     … It seems possible that Integer and the other wrapper types could be retro-fitted as value-safe types.  This is a major change, since wrapper objects would be unsynchronizable and their references interchangeable.  It is likely that code which violates value-safety for wrapper types exists but is uncommon.  It is less plausible to retro-fit String, since the prominent operation String.intern is often used with value-unsafe code. We should also reconsider the distinction between boxed and unboxed values in code.  The design presented above obscures that distinction.  As another thought experiment, we could imagine making a first class distinction in the type system between boxed and unboxed representations.  Since only primitive types are named with a lower-case initial letter, we could define that the capitalized version of a value type name always refers to the boxed representation, while the initial lower-case variant always refers to boxed.  For example: complex pi = complex.valueOf(Math.PI, 0); Complex boxPi = pi;  // convert to boxed myList.add(boxPi); complex z = myList.get(0);  // unbox Such a convention could perhaps absorb the current difference between int and Integer, double and Double. It might also allow the programmer to express a helpful distinction among array types. As said above, array types are crucial to bulk data interfaces, but are limited in the JVM.  Extending arrays beyond the present limitations is worth thinking about; for example, the Maxine JVM implementation has a hybrid object/array type.  Something like this which can also accommodate value type components seems worthwhile.  On the other hand, does it make sense for value types to contain short arrays?  And why should random-access arrays be the end of our design process, when bulk data is often sequentially accessed, and it might make sense to have heterogeneous streams of data as the natural “jumbo” data structure.  These considerations must wait for another day and another note. More Work It seems to me that a good sequence for introducing such value types would be as follows: Add the value-safety restrictions to an experimental version of javac. Code some sample applications with value types, including Complex and DecimalValue. Create an experimental JVM which internally unboxes value types but does not require new bytecodes to do so.  Ensure the feasibility of the performance model for the sample applications. Add tuple-like bytecodes (with or without generic type reification) to a major revision of the JVM, and teach the Java compiler to switch in the new bytecodes without code changes. A staggered roll-out like this would decouple language changes from bytecode changes, which is always a convenient thing. A similar investigation should be applied (concurrently) to array types.  In this case, it seems to me that the starting point is in the JVM: Add an experimental unboxing array data structure to a production JVM, perhaps along the lines of Maxine hybrids.  No bytecode or language support is required at first; everything can be done with encapsulated unsafe operations and/or method handles. Create an experimental JVM which internally unboxes value types but does not require new bytecodes to do so.  Ensure the feasibility of the performance model for the sample applications. Add tuple-like bytecodes (with or without generic type reification) to a major revision of the JVM, and teach the Java compiler to switch in the new bytecodes without code changes. That’s enough musing me for now.  Back to work!

  Read the article

• From Bluehost to WP Engine, My WordPress Story

  - by thatjeffsmith

  This is probably the longest blog post I’ve written in a LONG time. And if you’re used to coming here for the Oracle stuff, this post is not about that. It’s about my blog, and the stuff under the hood that makes it run, AKA WordPress. If you want to skip to the juicy stuff, then use these shortcuts: My Site Slowed Down How I Moved to WP Engine How WP Engine ‘Hooked’ Me Why WP Engine? I started thatJeffSmith.com on May 28th, 2010. I had been already been blogging for several years, but a couple of really smart people I respected (Andy, Brent – thanks again!) suggested that I take ownership of my content and begin building my personal brand. I thought that was a good idea, and so I signed up for service with bluehost. Bluehost makes setting up a WordPress site very, very easy. And, they continued to be easy to work with for the past 2 years. I would even recommend them to anyone looking to host their own WordPress install/site. For $83.40, I purchased a year’s worth of service and my domain name registration – a very good value. And then last year I paid $107.40 for another year’s services. And when that year expired I paid another $190.80 for an additional two year’s service in advance. I had been up to that point, getting my money’s worth. And then, just a few weeks ago… My Site Slowed to a Crawl That spike was from an April Fool's Day Post, I think Why? Well, when I first started blogging, I had the same problem that most beginner bloggers have – not many readers. In my first year of blogging, I think the highest number of readers on a single day was about 125. I remember that day as I was very excited to break 100! Bluehost was very reliable, serving up my content with maybe a total of 3-4 outages in the past 2 years. Support was usually very prompt with answers and solutions, and I love their ‘Chat now’ technology – much nicer than message boards only or pay-to-talk phone support. In the past 6 months however, I noticed a couple of things: daily traffic was increasing – woohoo! my service was experiencing severe CPU throttling – doh! To be honest, I wasn’t aware the throttling was occuring, but I did know that the response time of my blog was starting to lag. Average load times were approaching 20-30 seconds. Not good when good sites are loading in 5 seconds or less. And just this past week, in getting ready to launch a new website for work that sucked in an RSS feed from my blog, the new page was left waiting for more than a minute. Not good! In fact my boss asked, why aren’t you blogging on Blogger? Ugh. I tried a few things to fix the problem: I paid for a premium WordPress theme – Themify’s Grido (thanks to @SQLRockstar for the heads-up) I installed a couple of WP caching plugins I read every WP optimization blog post I could get my greedy little eyes on However, at the same time I was also getting addicted to WordPress bloggers talking about all the cool things you could do with your blog. As a result I had at one point about 30 different plugins installed. WordPress runs on MySQL, and certain queries running via these plugins were starving for CPU. Plugins that would be called every page load meant that as more people clicked on my site, the more CPU I needed. I’m not stupid, so I eventually figured out that maybe less plugins was better, and was able to go down to just 20. But still, the site was running like a dog. CPU Throttling, makes MySQL wait to run a query Bluehost runs shared servers. Your site runs on the same box that several hundred (or thousand?) other services are running on. If you take more CPU than they think you should have, they will limit your service by making you stand in line for CPU, AKA ‘throttling.’ This is not bad. This business model allows them to serve many, many users for a very fair price. It works great until, well, until it doesn’t. I noticed in the last week that for every minute of service, I was being throttled between 60 and 300 seconds. If there were 5 MySQL processes running, then every single one of them were being held in check. The blog visitor notice this as their page requests would take a minute or more to be answered. Bluehost unfortunately doesn’t offer dedicated server hosting, so there was no real upgrade path for me follow and remain one of their customers. So what was I to do? Uninstall every plugin and hope the site sped up? Ask for people to take turns on my blog? I decided to spend my way out of the problem. I signed up for service with WP Engine and moved ThatJeffSmith.com The first 2 months are free, and after that it’s about $29/month to run my site on their system. My math tells me that’s a good bit more expensive than what Bluehost was charging me – to the tune of about 300% more a month. Oh, and I should just say that my blog is a personal blog even though I talk about work stuff here. I don’t get paid for blogging, I don’t sell ads, and I don’t expense the service fees – this is my personal passion. So is it worth it? In the first 4 days, it seems to be totally worth it. Load times have gone from 20-30 seconds to less than 5 seconds. A few folks have told me via Twitter that they notice faster page loads. I anticipate this will indirectly lead to more traffic as Google penalizes you in search results if your site is too slow, and of course some folks won’t even bother waiting more than 5-10 seconds. I noticed right away that writing posts, uploading pictures, and just using the WordPress dashboard in general was much more responsive. So writing is less of a chore now, which means I won’t have a good reason not to write How I Moved to WP Engine I signed up for the service and registered my domain. I then took a full export of my ‘old’ site by doing a FTP GET of all my files, then did a MySQL database backup, exported my WordPress Theme settings to a .zip file, and then finally used the WordPress ‘Export’ feature. I then used the WordPress ‘Import’ on the new site to load up my posts. Then I uploaded the theme .zip package from Themify. Then I FTP’d the ‘wp-content’ directory up to my new server using SFTP (WP Engine only supports secure FTP – good on them!) Using a temporary URL to see my new site, I was able to confirm that everything looked mostly OK – I’ll detail the challenges and issues of fixing the content next – but then it was time to ‘flip the switch.’ I updated the IP address that the DNS lookup tables use to route traffic to my new server. In a matter of minutes the DNS servers around the world were updated and it was time to see the new site! But It Was ‘Broken’ I had never moved a website before, and in my rush to update the DNS, I had changed the records without really finding out what I was supposed to do first. After re-reading the directions provided by WP Engine and following the guidance of their support engineer, I realized I had needed to set the CNAME (Alias) ‘www’ record to point to a different URL than the ‘www.thatjeffsmith.com’ entry I had set. Once corrected the site was up and running in less than a minute. Then It Was Only Mostly Broken Many of my plugins weren’t working. Apparently just ftp’ing the wp-content directory up wasn’t the proper way to re-install the plugin. I suspect file permissions or file ownership wasn’t proper. Some plug-ins were working, many had their settings wiped to the defaults, and a few just didn’t work again. I had to delete the directory of the plug-in manually via SFTP, and then use the WP Dashboard to install it from scratch. And here was my first ‘lesson’ – don’t switch the DNS records until you’ve completely tested your new site. I wasn’t able to navigate the old WP console to review my plug-in settings. Thankfully I was able to use the Wayback Machine to reverse engineer some things, and of course most plug-ins aren’t that complicated to setup to begin with. An example of one that I had to redo from scratch is the ‘Twitter @Anywhere Plus’ plugin that I use to create the form that allows folks to tweet a post they enjoyed at the end of each story. How WP Engine ‘Hooked’ Me I actually signed up with another provider first. They ranked highly in Google searches and a few Tweeps recommended them to me. But hours after signing up and I still didn’t have sever reyady, I was ready to give up on them. They offered no chat or phone support – only mail and message boards. And the message boards were rife with posts about how the service had gone downhill in the past 6 months. To their credit, they did make it easy to cancel, although I did have to do so via email as their website ‘cancel’ button was non-existent. Within minutes of activating my WP Engine account I had received my welcome message and directions on how to get started. I was able to see my staged website right away. They also did something very cool before I even got started – they looked at my existing site and told me by how much they could improve its performance. The proof is in the web pudding. I like this for a few reasons, but primarily I liked their business model. It told me they knew what they were doing, and that they were willing to put their money where their mouth was. This was further evident by their 60-day money back guarantee. And if I understand it correctly, they don’t even take your money until after that 60 day period is over. After a day, I was welcomed by the WP Engine social media team, and was given the opportunity to subscribe to their newsletter and follow their account on Twitter. I noticed their Twitter team is sure to post regular WordPress tips several times a day. It’s not just an account that’s setup for the sake of having a Twitter presence. These little things add up and give me confidence in my decision to choose them as my hosting partner. ‘Partner’ – that’s a lot nicer word than just ‘service provider,’ isn’t it? Oh, and they offered me a t-shirt. Don’t ever doubt the power of a ‘free’ t-shirt! How awesome is this e-mail, from a customer perspective? I wasn’t really expecting any of this. Exceeding expectations before I have even handed over a single dollar seems like a pretty good business plan. This is how you treat customers. Love them to death, and they reward you with loyalty. But Jeff, You Skipped a Piece Here, Why WP Engine? I found them on one of those ‘Top 10′ list posts, and pulled up their webpage. I noticed they offered a specialized service – they host WordPress installs, and that’s it. Their servers are tuned specifically for running WordPress. They had in bolded text, things like ‘INSANELY FAST. INFINITELY SCALABLE.’ and ‘LIGHTNING SPEED.’ And then they offered insurance against hackers and they took care of automatic backups and restores. The only drawbacks I have noticed so far relate to plugins I used that have been ‘blacklisted.’ In order to guarantee that ‘lightning’ speed, they have banned the use of the CPU-suckiest plugins. One of those is the ‘Related Posts’ plugin. So if you are a subscriber and are reading this in your email, you’ll notice there’s no links back to my blog to continue reading other related stories. Since that referral traffic is very small single-digit for my site, I decided that I’m OK with that. I’d rather have the warp-speed page loads. Again, I think that will lead to higher traffic down the road. In 50+ days I will need to decide if WP Engine is a permanent solution. I’ll be sure to update this post when that time comes and let y’all know how it turns out.

  Read the article

• Exam 71-516: Accessing Data with Microsoft .NET Framework 4

  - by Ricardo Peres

  I had the chance to take the beta version of exam 71-516 today. Here are my thoughts on it: first, I was rather annoyed to discover that I will only know if I passed or not about 8 weeks after the beta period expires (July, 02), which probably means September. It was a difficult exam, especially since I don't have any practice on some of the new Entity Framework options. The items covered, from the most covered to the least covered, were: Entity Framework (50-50 for POCO/Non-POCO) LINQ to SQL WCF Data Services Classic ADO.NET (DataSets, DataTables, DataAdapters, TableAdapters, Connections and Commands LINQ to XML Sync Framework (surprise!) All added up, I think it was a difficult exam. My advise is that you practice a lot! I will post the result as soon as I know it.

  Read the article

• Best practices for logging user actions in production

  - by anthonypliu

  I was planning on logging a lot of different stuff in my production environment, things like when a user: Logs In, Logs Off Change Profile Edit Account settings Change password ... etc Is this a good practice to do on a production enviornment? Also what is a good way to log all this. I am currently using the following code block to log to: public void LogMessageToFile(string msg) { System.IO.StreamWriter sw = System.IO.File.AppendText( GetTempPath() + @"MyLogFile.txt"); try { string logLine = System.String.Format( "{0:G}: {1}.", System.DateTime.Now, msg); sw.WriteLine(logLine); } finally { sw.Close(); } } Will this be ok for production? My application is very new so im not expecting millions of users right away or anything, looking for the best practices to keeping track of actions on a website or if its even best practice to.

  Read the article

• Adding attachments to HumanTasks *beforehand*

  - by ccasares

  For an demo I'm preparing along with a partner, we need to add some attachments to a HumanTask beforehand, that is, the attachment must be associated already to the Task by the time the user opens its Form. How to achieve this?, indeed it's quite simple and just a matter of some mappings to the Task's input execData structure. Oracle BPM supports "default" attachments (which use BPM tables) or UCM-based ones. The way to insert attachments for both methods is pretty similar. With default attachments When using default attachments, first we need to have the attachment payload as part of the BPM process, that is, must be contained in a variable. Normally the attachment content is binary, so we'll need first to convert it to a base64-string (not covered on this blog entry). What we need to do is just to map the following execData parameters as part of the input of the HumanTask: execData.attachment[n].content            <-- the base64 payload data execData.attachment[n].mimeType           <-- depends on your attachment                                               (e.g.: "application/pdf") execData.attachment[n].name               <-- attachment name (just the name you want to                                               use. No need to be the original filename) execData.attachment[n].attachmentScope    <-- BPM or TASK (depending on your needs) execData.attachment[n].storageType        <-- TASK execData.attachment[n].doesBelongToParent <-- false (not sure if this one is really                                               needed, but it definitely doesn't hurt) execData.attachment[n].updatedBy          <-- username who is attaching it execData.attachment[n].updatedDate        <-- dateTime of when this attachment is                                               attached  Bear in mind that the attachment structure is a repetitive one. So if you need to add more than one attachment, you'll need to use XSLT mapping. If not, the Assign mapper automatically adds [1] for the iteration.  With UCM-based attachments With UCM-based attachments, the procedure is basically the same. We'll need to map some extra fields and not to map others. The tricky part with UCM-based attachments is what we need to know beforehand about the attachment itself. Of course, we don't need to have the payload, but a couple of information from the attachment that must be checked in already in UCM. First, let's see the mappings: execData.attachment[n].mimeType           <-- Document's dFormat attribute (1) execData.attachment[n].name               <-- attachment name (just the name you want to                                               use. No need to be the original filename) execData.attachment[n].attachmentScope    <-- BPM or TASK (depending on your needs) execData.attachment[n].storageType        <-- UCM execData.attachment[n].doesBelongToParent <-- false (not sure if this one is really                                               needed, but it definitely doesn't hurt) execData.attachment[n].updatedBy          <-- username who is attaching it execData.attachment[n].updatedDate        <-- dateTime of when this attachment is                                               attached  execData.attachment[n].uri                <-- "ecm://<dID>" where dID is document's dID                                      attribute (2) execData.attachment[n].ucmDocType         <-- Document's dDocType attribute (3) execData.attachment[n].securityGroup      <-- Document's dSecurityGroup attribute (4) execData.attachment[n].revision           <-- Document's dRevisionID attribute (5) execData.attachment[n].ucmMetadataItem[1].name  <-- "DocUrl" execData.attachment[n].ucmMetadataItem[1].type  <-- STRING execData.attachment[n].ucmMetadataItem[1].value <-- Document's url attribute (6)  Where to get those (n) fields? In my case I get those from a Search call to UCM (not covered on this blog entry) As I mentioned above, we must know which UCM document we're going to attach. We may know its ID, its name... whatever we need to uniquely identify it calling the IDC Search method. This method returns ALL the info we need to attach the different fields labeled with a number above.  The only tricky one is (6). UCM Search service returns the url attribute as a context-root without hostname:port. E.g.: /cs/groups/public/documents/document/dgvs/mdaw/~edisp/ccasareswcptel000239.pdf However we do need to include the full qualified URL when mapping (6). Where to get the http://<hostname>:<port> value? Honestly, I have no clue. What I use to do is to use a BPM property that can always be modified at runtime if needed. There are some other fields that might be needed in the execData.attachment structure, like account (if UCM's is using Accounts). But for demos I've never needed to use them, so I'm not sure whether it's necessary or not. Feel free to add some comments to this entry if you know it ;-)  That's all folks. Should you need help with the UCM Search service, let me know and I can write a quick entry on that topic.

  Read the article

• What is the exception in java code? [closed]

  - by Karandeep Singh

  This java code is for reverse the string but it returning concat null with returned string. import java.util.*; import java.util.logging.Level; import java.util.logging.Logger; public class Practice { public static void main(String[] args) { String str = ""; try { str = reverse("Singh"); } catch (Exception ex) { Logger.getLogger(Practice.class.getName()).log(Level.SEVERE, null, ex); System.out.print(ex.getMessage()); }finally{ System.out.println(str); } } public static String reverse(String str) throws Exception{ String temp = null; if(str.length()<=0){ throw new Exception("empty"); }else{ for(int i=str.length()-1;i>=0;i--){ temp+=str.charAt(i); } } return temp.trim(); } } Output: nullhgniS

  Read the article

• Use a template to get alternate behaviour?

  - by Serge

  Is this a bad practice? const int sId(int const id); // true/false it doesn't matter template<bool i> const int sId(int const id) { return this->id = id; } const int MCard::sId(int const id){ MCard card = *this; this->id = id; this->onChange.fire(EventArgs<MCard&, MCard&>(*this, card)); return this->id; } myCard.sId(9); myCard.sId<true>(8); As you can see, my goal is to be able to have an alternative behaviour for sId. I know I could use a second parameter to the function and use a if, but this feels more fun (imo) and might prevent branch prediction (I'm no expert in that field). So, is it a valid practice, and/or is there a better approach?

  Read the article

• Please help me give this principle a name

  - by Brent Arias

  As a designer, I like providing interfaces that cater to a power/simplicity balance. For example, I think the LINQ designers followed that principle because they offered both dot-notation and query-notation. The first is more powerful, but the second is easier to read and follow. If you disagree with my assessment of LINQ, please try to see my point anyway; LINQ was just an example, my post is not about LINQ. I call this principle "dial-able power". But I'd like to know what other people call it. Certainly some will say "KISS" is the common term. But I see KISS as a superset, or a "consumerism" practice. Using LINQ as my example again, in my view, a team of programmers who always try to use query notation over dot-notation are practicing KISS. Thus the LINQ designers practiced "dial-able power", whereas the LINQ consumers practice KISS. The two make beautiful music together. I'll give another example. Imagine a C# logging tool that has two signatures allowing two uses: void Write(string message); void Write(Func<string> messageCallback); The purpose of the two signatures is to fulfill these needs: //Every-day "simple" usage, nothing special. myLogger.Write("Something Happened" + error.ToString() ); //This is performance critical, do not call ToString() if logging is //disabled. myLogger.Write( () => { "Something Happened" + error.ToString() }); Having these overloads represents "dial-able power," because the consumer has the choice of a simple interface or a powerful interface. A KISS-loving consumer will use the simpler signature most of the time, and will allow the "busy" looking signature when the power is needed. This also helps self-documentation, because usage of the powerful signature tells the reader that the code is performance critical. If the logger had only the powerful signature, then there would be no "dial-able power." So this comes full-circle. I'm happy to keep my own "dial-able power" coinage if none yet exists, but I can't help think I'm missing an obvious designation for this practice. p.s. Another example that is related, but is not the same as "dial-able power", is Scott Meyer's principle "make interfaces easy to use correctly, and hard to use incorrectly."

  Read the article

• Do most programmers copy and paste code?

  - by John MacIntyre

  I learned very early on that cutting & pasting somebody else's code takes longer in the long run that writing it yourself. In my opinion unless you really understand it, cut & paste code will probably have issues which will be a nightmare to resolve. Don't get me wrong, I mean finding other peoples code and learning from it is essential, but we don't just paste it into our app. We rewrite the concepts into our app. But I'm constantly hearing about people who cut & paste, and they talk about it like it's common practice. I also see comments by others which indicate it's common practice. So, do most programmers cut & paste code?

  Read the article

• Sorting and Filtering By Model-Based LOV Display Value

  - by Steven Davelaar

  If you use a model-based LOV and you use display type "choice", then ADF nicely displays the display value, even if the table is read-only. In the screen shot below, you see the RegionName attribute displayed instead of the RegionId. This is accomplished by the model-based LOV, I did not modify the Countries view object to include a join with Regions.  Also note the sort icon, the table is sorted by RegionId. This sorting typically results in a bug reported by your test team. Europe really shouldn't come before America when sorting ascending, right? To fix this, we could of course change the Countries view object query and add a join with the Regions table to include the RegionName attribute. If the table is updateable, we still need the choice list, so we need to move the model-based LOV from the RegionId attribute to the RegionName attribute and hide the RegionId attribute in the table. But that is a lot of work for such a simple requirement, in particular if we have lots of model-based choice lists in our view object. Fortunately, there is an easier way to do this, with some generic code in your view object base class that fixes this at once for all model-based choice lists that we have defined in our application. The trick is to override the method getSortCriteria() in the base view object class. By default, this method returns null because the sorting is done in the database through a SQL Order By clause. However, if the getSortCriteria method does return a sort criteria the framework will perform in memory sorting which is what we need to achieve sorting by region name. So, inside this method we need to evaluate the Order By clause, and if the order by column matches an attribute that has a model-based LOV choicelist defined with a display attribute that is different from the value attribute, we need to return a sort criterria. Here is the complete code of this method: public SortCriteria[] getSortCriteria() {   String orderBy = getOrderByClause();          if (orderBy!=null )   {     boolean descending = false;     if (orderBy.endsWith(" DESC"))      {       descending = true;       orderBy = orderBy.substring(0,orderBy.length()-5);     }     // extract column name, is part after the dot     int dotpos = orderBy.lastIndexOf(".");     String columnName = orderBy.substring(dotpos+1);     // loop over attributes and find matching attribute     AttributeDef orderByAttrDef = null;     for (AttributeDef attrDef : getAttributeDefs())     {       if (columnName.equals(attrDef.getColumnName()))       {         orderByAttrDef = attrDef;         break;       }     }     if (orderByAttrDef!=null && "choice".equals(orderByAttrDef.getProperty("CONTROLTYPE"))          && orderByAttrDef.getListBindingDef()!=null)     {       String orderbyAttr = orderByAttrDef.getName();       String[] displayAttrs = orderByAttrDef.getListBindingDef().getListDisplayAttrNames();       String[] listAttrs = orderByAttrDef.getListBindingDef().getListAttrNames();       // if first list display attributes is not the same as first list attribute, than the value       // displayed is different from the value copied back to the order by attribute, in which case we need to       // use our custom comparator       if (displayAttrs!=null && listAttrs!=null && displayAttrs.length>0 && !displayAttrs[0].equals(listAttrs[0]))       {                  SortCriteriaImpl sc1 = new SortCriteriaImpl(orderbyAttr, descending);         SortCriteria[] sc = new SortCriteriaImpl[]{sc1};         return sc;                           }     }     }   return super.getSortCriteria(); } If this method returns a sort criteria, then the framework will call the sort method on the view object. The sort method uses a Comparator object to determine the sequence in which the rows should be returned. This comparator is retrieved by calling the getRowComparator method on the view object. So, to ensure sorting by our display value, we need to override this method to return our custom comparator: public Comparator getRowComparator() {   return new LovDisplayAttributeRowComparator(getSortCriteria()); } The custom comparator class extends the default RowComparator class and overrides the method compareRows and looks up the choice display value to compare the two rows. The complete code of this class is included in the sample application.  With this code in place, clicking on the Region sort icon nicely sorts the countries by RegionName, as you can see below. When using the Query-By-Example table filter at the top of the table, you typically want to use the same choice list to filter the rows. One way to do that is documented in ADF code corner sample 16 - How To Customize the ADF Faces Table Filter.The solution in this sample is perfectly fine to use. This sample requires you to define a separate iterator binding and associated tree binding to populate the choice list in the table filter area using the af:iterator tag. You might be able to reuse the same LOV view object instance in this iterator binding that is used as view accessor for the model-bassed LOV. However, I have seen quite a few customers who have a generic LOV view object (mapped to one "refcodes" table) with the bind variable values set in the LOV view accessor. In such a scenario, some duplicate work is needed to get a dedicated view object instance with the correct bind variables that can be used in the iterator binding. Looking for ways to maximize reuse, wouldn't it be nice if we could just reuse our model-based LOV to populate this filter choice list? Well we can. Here are the basic steps: 1. Create an attribute list binding in the page definition that we can use to retrieve the list of SelectItems needed to populate the choice list <list StaticList="false" Uses="LOV_RegionId"               IterBinding="CountriesView1Iterator" id="RegionId"/>  We need this "current row" list binding because the implicit list binding used by the item in the table is not accessible outside a table row, we cannot use the expression #{row.bindings.RegionId} in the table filter facet. 2. Create a Map-style managed bean with the get method retrieving the list binding as key, and returning the list of SelectItems. To return this list, we take the list of selectItems contained by the list binding and replace the index number that is normally used as key value with the actual attribute value that is set by the choice list. Here is the code of the get method:  public Object get(Object key) {   if (key instanceof FacesCtrlListBinding)   {     // we need to cast to internal class FacesCtrlListBinding rather than JUCtrlListBinding to     // be able to call getItems method. To prevent this import, we could evaluate an EL expression     // to get the list of items     FacesCtrlListBinding lb = (FacesCtrlListBinding) key;     if (cachedFilterLists.containsKey(lb.getName()))     {       return cachedFilterLists.get(lb.getName());     }     List<SelectItem> items = (List<SelectItem>)lb.getItems();     if (items==null || items.size()==0)     {       return items;     }     List<SelectItem> newItems = new ArrayList<SelectItem>();     JUCtrlValueDef def = ((JUCtrlValueDef)lb.getDef());     String valueAttr = def.getFirstAttrName();     // the items list has an index number as value, we need to replace this with the actual     // value of the attribute that is copied back by the choice list     for (int i = 0; i < items.size(); i++)     {       SelectItem si = (SelectItem) items.get(i);       Object value = lb.getValueFromList(i);       if (value instanceof Row)       {         Row row = (Row) value;         si.setValue(row.getAttribute(valueAttr));                 }       else       {         // this is the "empty" row, set value to empty string so all rows will be returned         // as user no longer wants to filter on this attribute         si.setValue("");       }       newItems.add(si);     }     cachedFilterLists.put(lb.getName(), newItems);     return newItems;   }   return null; } Note that we added caching to speed up performance, and to handle the situation where table filters or search criteria are set such that no rows are retrieved in the table. When there are no rows, there is no current row and the getItems method on the list binding will return no items.  An alternative approach to create the list of SelectItems would be to retrieve the iterator binding from the list binding and loop over the rows in the iterator binding rowset. Then we wouldn't need the import of the ADF internal oracle.adfinternal.view.faces.model.binding.FacesCtrlListBinding class, but then we need to figure out the display attributes from the list binding definition, and possible separate them with a dash if multiple display attributes are defined in the LOV. Doable but less reuse and more work. 3. Inside the filter facet for the column create an af:selectOneChoice with the value property of the f:selectItems tag referencing the get method of the managed bean:  <f:facet name="filter">   <af:selectOneChoice id="soc0" autoSubmit="true"                       value="#{vs.filterCriteria.RegionId}">     <!-- attention: the RegionId list binding must be created manually in the page definition! -->                       <f:selectItems id="si0"                    value="#{viewScope.TableFilterChoiceList[bindings.RegionId]}"/>   </af:selectOneChoice> </f:facet> Note that the managed bean is defined in viewScope for the caching to take effect. Here is a screen shot of the tabe filter in action: You can download the sample application here. 

  Read the article

• I prefer C/C++ over Unity and other tools: is it such a big downer for a game developper ?

  - by jokoon

  We have a big game project on Unity at school on which we are 12 to work on. My teacher seems to be convinced it's an important tool to teach students, since it makes students look from the high level to the lower level. I can understand his view, and I'm wondering: Is unity such an important engine in game developping companies ? Are there a lot of companies using it because they can't afford to use something else ? He is talking like Unity is a big player in game making, but I only see it fit small indie game companies who want to do a game as fast as possible. Do you think Unity is that much important in the industry ? Does it endangers the value of C++ skills ? It's not that I don't like Unity, it's just that I don't learn nothing with it, I prefer to achieve little steps with Ogre or SFML instead. Also, we also have C++ practice exercises, but those are just practice with theory, nothing much.

  Read the article

• Do most programmers cut & paste code?

  - by John MacIntyre

  I learned very early on that cutting & pasting somebody else's code takes longer in the long run that writing it yourself. In my opinion unless you really understand it, cut & paste code will probably have issues which will be a nightmare to resolve. Don't get me wrong, I mean finding other peoples code and learning from it is essential, but we don't just paste it into our app. We rewrite the concepts into our app. But I'm constantly hearing about people who cut & paste, and they talk about it like it's common practice. I also see comments by others which indicate it's common practice. So, do most programmers cut & paste code?

  Read the article

• I prefer C/C++ over Unity and other tools: is it such a big downer for a game developer?

  - by jokoon

  We have a big game project using Unity at school. There are 12 of us working on it. My teacher seems to be convinced it's an important tool to teach students, since it makes students look from the high level to the lower level. I can understand his view, and I'm wondering: Is unity such an important engine in game development companies? Are there a lot of companies using it because they can't afford to use something else? He is talking like Unity is a big player in game making, but I only see it fit small indie game companies who want to do a game as fast as possible. Do you think Unity is of that much importance in the industry? Does it endanger the value of C++ skills? It's not that I don't like Unity, it's just that I don't learn anything with it, I prefer to achieve little steps with Ogre or SFML instead. Also, we also have C++ practice exercises, but those are just practice with theory, nothing much.

  Read the article

• Connecting SceneBuilder edited FXML to Java code

  - by daniel

  Recently I had to answer several questions regarding how to connect an UI built with the JavaFX SceneBuilder 1.0 Developer Preview to Java Code. So I figured out that a short overview might be helpful. But first, let me state the obvious. What is FXML? To make it short, FXML is an XML based declaration format for JavaFX. JavaFX provides an FXML loader which will parse FXML files and from that construct a graph of Java object. It may sound complex when stated like that but it is actually quite simple. Here is an example of FXML file, which instantiate a StackPane and puts a Button inside it: -- <?xml version="1.0" encoding="UTF-8"?> <?import java.lang.*?> <?import java.util.*?> <?import javafx.scene.control.*?> <?import javafx.scene.layout.*?> <?import javafx.scene.paint.*?> <StackPane prefHeight="150.0" prefWidth="200.0" xmlns:fx="http://javafx.com/fxml"> <children> <Button mnemonicParsing="false" text="Button" /> </children> </StackPane> ... and here is the code I would have had to write if I had chosen to do the same thing programatically: import javafx.scene.control.*; import javafx.scene.layout.*; ... final Button button = new Button("Button"); button.setMnemonicParsing(false); final StackPane stackPane = new StackPane(); stackPane.setPrefWidth(200.0); stackPane.setPrefHeight(150.0); stacPane.getChildren().add(button); As you can see - FXML is rather simple to understand - as it is quite close to the JavaFX API. So OK FXML is simple, but why would I use it?Well, there are several answers to that - but my own favorite is: because you can make it with SceneBuilder. What is SceneBuilder? In short SceneBuilder is a layout tool that will let you graphically build JavaFX user interfaces by dragging and dropping JavaFX components from a library, and save it as an FXML file. SceneBuilder can also be used to load and modify JavaFX scenegraphs declared in FXML. Here is how I made the small FXML file above: Start the JavaFX SceneBuilder 1.0 Developer Preview In the Library on the left hand side, click on 'StackPane' and drag it on the content view (the white rectangle) In the Library, select a Button and drag it onto the StackPane on the content view. In the Hierarchy Panel on the left hand side - select the StackPane component, then invoke 'Edit > Trim To Selected' from the menubar That's it - you can now save, and you will obtain the small FXML file shown above. Of course this is only a trivial sample, made for the sake of the example - and SceneBuilder will let you create much more complex UIs. So, I have now an FXML file. But what do I do with it? How do I include it in my program? How do I write my main class? Loading an FXML file with JavaFX Well, that's the easy part - because the piece of code you need to write never changes. You can download and look at the SceneBuilder samples if you need to get convinced, but here is the short version: Create a Java class (let's call it 'Main.java') which extends javafx.application.Application In the same directory copy/save the FXML file you just created using SceneBuilder. Let's name it "simple.fxml" Now here is the Java code for the Main class, which simply loads the FXML file and puts it as root in a stage's scene. /* * Copyright (c) 2012, Oracle and/or its affiliates. All rights reserved. */ package simple; import java.util.logging.Level; import java.util.logging.Logger; import javafx.application.Application; import javafx.fxml.FXMLLoader; import javafx.scene.Scene; import javafx.scene.layout.StackPane; import javafx.stage.Stage; public class Main extends Application { /** * @param args the command line arguments */ public static void main(String[] args) { Application.launch(Main.class, (java.lang.String[])null); } @Override public void start(Stage primaryStage) { try { StackPane page = (StackPane) FXMLLoader.load(Main.class.getResource("simple.fxml")); Scene scene = new Scene(page); primaryStage.setScene(scene); primaryStage.setTitle("FXML is Simple"); primaryStage.show(); } catch (Exception ex) { Logger.getLogger(Main.class.getName()).log(Level.SEVERE, null, ex); } } } Great! Now I only have to use my favorite IDE to compile the class and run it. But... wait... what does it do? Well nothing. It just displays a button in the middle of a window. There's no logic attached to it. So how do we do that? How can I connect this button to my application logic? Here is how: Connection to code First let's define our application logic. Since this post is only intended to give a very brief overview - let's keep things simple. Let's say that the only thing I want to do is print a message on System.out when the user clicks on my button. To do that, I'll need to register an action handler with my button. And to do that, I'll need to somehow get a handle on my button. I'll need some kind of controller logic that will get my button and add my action handler to it. So how do I get a handle to my button and pass it to my controller? Once again - this is easy: I just need to write a controller class for my FXML. With each FXML file, it is possible to associate a controller class defined for that FXML. That controller class will make the link between the UI (the objects defined in the FXML) and the application logic. To each object defined in FXML we can associate an fx:id. The value of the id must be unique within the scope of the FXML, and is the name of an instance variable inside the controller class, in which the object will be injected. Since I want to have access to my button, I will need to add an fx:id to my button in FXML, and declare an @FXML variable in my controller class with the same name. In other words - I will need to add fx:id="myButton" to my button in FXML: -- <Button fx:id="myButton" mnemonicParsing="false" text="Button" /> and declare @FXML private Button myButton in my controller class @FXML private Button myButton; // value will be injected by the FXMLLoader Let's see how to do this. Add an fx:id to the Button object Load "simple.fxml" in SceneBuilder - if not already done In the hierarchy panel (bottom left), or directly on the content view, select the Button object. Open the Properties sections of the inspector (right panel) for the button object At the top of the section, you will see a text field labelled fx:id. Enter myButton in that field and validate. Associate a controller class with the FXML file Still in SceneBuilder, select the top root object (in our case, that's the StackPane), and open the Code section of the inspector (right hand side) At the top of the section you should see a text field labelled Controller Class. In the field, type simple.SimpleController. This is the name of the class we're going to create manually. If you save at this point, the FXML will look like this: -- <?xml version="1.0" encoding="UTF-8"?> <?import java.lang.*?> <?import java.util.*?> <?import javafx.scene.control.*?> <?import javafx.scene.layout.*?> <?import javafx.scene.paint.*?> <StackPane prefHeight="150.0" prefWidth="200.0" xmlns:fx="http://javafx.com/fxml" fx:controller="simple.SimpleController"> <children> <Button fx:id="myButton" mnemonicParsing="false" text="Button" /> </children> </StackPane> As you can see, the name of the controller class has been added to the root object: fx:controller="simple.SimpleController" Coding the controller class In your favorite IDE, create an empty SimpleController.java class. Now what does a controller class looks like? What should we put inside? Well - SceneBuilder will help you there: it will show you an example of controller skeleton tailored for your FXML. In the menu bar, invoke View > Show Sample Controller Skeleton. A popup appears, displaying a suggestion for the controller skeleton: copy the code displayed there, and paste it into your SimpleController.java: /** * Sample Skeleton for "simple.fxml" Controller Class * Use copy/paste to copy paste this code into your favorite IDE **/ package simple; import java.net.URL; import java.util.ResourceBundle; import javafx.fxml.FXML; import javafx.fxml.Initializable; import javafx.scene.control.Button; public class SimpleController implements Initializable { @FXML // fx:id="myButton" private Button myButton; // Value injected by FXMLLoader @Override // This method is called by the FXMLLoader when initialization is complete public void initialize(URL fxmlFileLocation, ResourceBundle resources) { assert myButton != null : "fx:id=\"myButton\" was not injected: check your FXML file 'simple.fxml'."; // initialize your logic here: all @FXML variables will have been injected } } Note that the code displayed by SceneBuilder is there only for educational purpose: SceneBuilder does not create and does not modify Java files. This is simply a hint of what you can use, given the fx:id present in your FXML file. You are free to copy all or part of the displayed code and paste it into your own Java class. Now at this point, there only remains to add our logic to the controller class. Quite easy: in the initialize method, I will register an action handler with my button: () { @Override public void handle(ActionEvent event) { System.out.println("That was easy, wasn't it?"); } }); ... -- ... // initialize your logic here: all @FXML variables will have been injected myButton.setOnAction(new EventHandler<ActionEvent>() { @Override public void handle(ActionEvent event) { System.out.println("That was easy, wasn't it?"); } }); ... That's it - if you now compile everything in your IDE, and run your application, clicking on the button should print a message on the console! Summary What happens is that in Main.java, the FXMLLoader will load simple.fxml from the jar/classpath, as specified by 'FXMLLoader.load(Main.class.getResource("simple.fxml"))'. When loading simple.fxml, the loader will find the name of the controller class, as specified by 'fx:controller="simple.SimpleController"' in the FXML. Upon finding the name of the controller class, the loader will create an instance of that class, in which it will try to inject all the objects that have an fx:id in the FXML. Thus, after having created '<Button fx:id="myButton" ... />', the FXMLLoader will inject the button instance into the '@FXML private Button myButton;' instance variable found on the controller instance. This is because The instance variable has an @FXML annotation, The name of the variable exactly matches the value of the fx:id Finally, when the whole FXML has been loaded, the FXMLLoader will call the controller's initialize method, and our code that registers an action handler with the button will be executed. For a complete example, take a look at the HelloWorld SceneBuilder sample. Also make sure to follow the SceneBuilder Get Started guide, which will guide you through a much more complete example. Of course, there are more elegant ways to set up an Event Handler using FXML and SceneBuilder. There are also many different ways to work with the FXMLLoader. But since it's starting to be very late here, I think it will have to wait for another post. I hope you have enjoyed the tour! --daniel

  Read the article

• Intentional misspellings to avoid reserved words

  - by Renesis

  I often see code that include intentional misspellings of common words that for better or worse have become reserved words: klass or clazz for class: Class clazz = ThisClass.class kount for count in SQL: count(*) AS kount Personally I find this decreases readability. In my own practice I haven't found too many cases where a better name couldn't have been used — itemClass or recordTotal. However, it's so common that I can't help but wonder if I'm the only one? Anyone have any advice or even better, quoted recommendations from well-respected programmers on this practice?

  Read the article

• Are flag variables an absolute evil?

  - by dukeofgaming

  I remember doing a couple of projects where I totally neglected using flags and ended up with better architecture/code; however, it is a common practice in other projects I work at, and when code grows and flags are added, IMHO code-spaghetti also grows. Would you say there are any cases where using flags is a good practice or even necessary?, or would you agree that using flags in code are... red flags and should be avoided/refactored; me, I just get by with doing functions/methods that check for states in real time instead. Edit: Not talking about compiler flags

  Read the article

• Why use string.Empty over "" when assigning to a string object

  - by dreza

  I've been running StyleCop over my code and one of the recommendations SA1122 is to use string.Empty rather than "" when assigning an empty string to a value. My question is why is this considered best practice. Or, is this considered best practice? I assume there is no compiler difference between the two statements so I can only think that it's a readability thing? UPDATE: Thanks for the answers but it's been kindly pointed out this question has been asked many times already on SO, which in hind-sight I should have considered and searched first before asking here. Some of these especially forward links makes for interesting reading. SO question and answer Jon Skeet answer to question

  Read the article

• Javascript naming conventions

  - by ManuPK

  I am from Java background and am new to JavaScript. I have noticed many JavaScript methods using single character parameter names, such as in the following example. doSomething(a,b,c) I don't like it, but a fellow JavaScript developer convinced me that this is done to reduce the file size, noting that JavaScript files have to be transferred to the browser. Then I found myself talking to another developer. He showed me the way that Firefox will truncate variable names to load the page faster. Is this a standard practice for web browsers? What are the best-practice naming conversions that should be followed when programming in JavaScript? Does identifier length matter, and if so, to what extent?

  Read the article

• How Cloud Computing Security Resembles the Financial Meltdown

  A Gartner analyst report questions the practice of software as a service vendors paying for SAS 70 certifications.

  Read the article

• How Cloud Computing Security Resembles the Financial Meltdown

  A Gartner analyst report questions the practice of software as a service vendors paying for SAS 70 certifications.

  Read the article

• Learning the nuances of a language (C++)

  - by prelic

  So I'm a recent college graduate, and I really enjoy working in C++; I worked with it a lot in school, and would like to pursue a career writing in C or C++. The problem I'm having is that I'm trying to learn the nuances of C++. I'm not talking about the basics, or even advanced concepts like templates, namespaces, etc. I'm talking about the real nitty-gritty stuff like undefined behavior and stuff like that. When I'm interviewing, and they put a bizarre piece of C++ code in front of me, and ask me what the output will be, I want to be able to nail those questions. Obviously experience is a great way to learn, but when I write code for practice, I [obviously] know what it does. Reading open-source projects have been good practice, but I find that there tends to be an enormous learning curve just understanding the organization of the code (because the projects tend to be large). So basically what I'm asking is, what should I do now?

  Read the article

• Does NASA license the software that it develops?

  - by Abe

  NASA provides a visualization software called Panoply. There is a Credits and Acknowledgments page that acknowledges and lists the licenses of software dependencies, but provides no information about its own license. I have looked at other software produced by NASA, including the source code for GISS and can not find any information about a licence. The closest information that I can find is in the FAQ for the global climate model EdGCM Global that says the code is in the "public domain" is it standard practice at NASA to release code into the public domain? are there exceptions? Can I assume that Panoply is public domain and can be used without restriction other than than those imposed by licenses of software dependencies? Is the absence of specific permission to reuse the code a concern (this issue was raised in the answer to a separate question) How common is this practice across government agencies?

  Read the article

< Previous Page | 500 501 502 503 504 505 506 507 508 509 510 511  | Next Page >