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Rifidi Edge Server Developer’s Guide

Version 1.0 (Rifidi Edge Server version 1.2) September 2010

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Table of Contents
Overview ....................................................................................................................................................... 4 Getting Started with the SDK ........................................................................................................................ 4 Overview of SDK........................................................................................................................................ 4 Documentation ......................................................................................................................................... 4 Setting up a Development Environment .................................................................................................. 4 Importing a Project Template ................................................................................................................... 4 Running the project .................................................................................................................................. 5 Setting up Configuration Files ................................................................................................................... 5 Viewing and Modifying the Rifidi Source Code......................................................................................... 5 Rifid Edge Server Architecture ...................................................................................................................... 6 Sensor Abstraction Layer .......................................................................................................................... 6 Application Engine Layer........................................................................................................................... 6 Communication Layer ............................................................................................................................... 7 Sensor Layer .................................................................................................................................................. 7 Creating a New Sensor Adapter ................................................................................................................ 8 Anatomy of a Sensor Plugin ...................................................................................................................... 8 Sensor Sessions ......................................................................................................................................... 9 AbstractSensorSession ........................................................................................................................ 10 AbstractIPSensorSession ..................................................................................................................... 10 AbstractServerSocketSensorSession ................................................................................................... 10 AbstractSerialSensorSession ............................................................................................................... 11 Sensors .................................................................................................................................................... 11 Sensor Factories ...................................................................................................................................... 11 Persistence .............................................................................................................................................. 11 General Purpose I/O ............................................................................................................................... 11 Tag Writing .............................................................................................................................................. 12 Application Layer ........................................................................................................................................ 12 Rifidi Application API ............................................................................................................................... 12 Lifecycle Management ........................................................................................................................ 14 Configuration Management................................................................................................................ 14 Esper Management ............................................................................................................................. 16

............................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................. 22 Webservice ..................................................................................................................................................... 20 Integration Layer ................................... 21 JMS .................................................................................................................................................................................... 20 Tag Generator ...................................................................... 18 Stable Set Service ..................................................................... 18 Unique Tag Batch Interval Service ......................................................................................................................... 19 Sensor Status Monitoring Service ................................................................................... 18 Unique Tag Interval Service ................................................................................................................... 23 Northwind Business Rules......................................................................................... 21 Databases ............................... 22 Exporting and Deploying .............................................................................................................................................................................. 17 Rifidi Services . 19 Serial......................................................................................... 19 Diagnostic Applications ................................................................................ 17 Read Zone Monitoring Service ............................ 24 Northwind Application Architecture................................................. 23 Setting up and running the Northwind Example ..................................................................................................................................................................................................................................................................3 Plugging into the OSGi console ..................................................................................................................... 20 Tags ........................................................................................................................................................................................................... 25 ........................................................................ 19 GPIO ................................... 22 Example: Northwind ................................................................... 22 RMI ...................................................................................................................................................

Please follow the instructions on this wiki page to import the SDK into your eclipse workspace: http://wiki. It can be found at http://wiki. it is recommended that you import a project template from the examples directory in the SDK.php/Edge_Server_Development_Environment Importing a Project Template Now that you’ve set up your development environment. It can be found online at http://forums. Instead of following step by step instructions on how to set up an application. .org/index.org/javadoc/edge1.rifidi. To do this. and how to create your first Rifidi application project.2. It describes the structure of the SDK. you will need to use Eclipse.rifidi.0 The wiki has some helpful pages to answer some common questions that users and developers have. This document describes the features and tools available to application developers in the Rifidi Edge Server Standard Development Kit (SDK).4 Overview The Rifidi Edge Server is an application platform that provides developers with a way to quickly develop and deploy RFID applications. how to set up a development environment. Getting Started with the SDK This chapter will help you get started using the Rifidi Edge Server SDK. you will want to create a Rifidi application project. docs – Contains all the documentation launch file – The default run configuration to run the edge server from within eclipse target file – The file that tells eclipse where to find the necessary dependencies to run the edge server Documentation There are several places to look for specific documentation needs      The User Documentation is a PDF that explains how to run and control the Rifidi Edge Server The Developer Documentation (this document) explains how to develop reader adapters and plugins for our Edge Server The Javadoc for the Rifidi API can be found online at http://www.rifidi.org Setting up a Development Environment In order to develop a Rifidi application.org The forums provide a way for users and developers to ask questions. Overview of SDK The SDK contains the following files and folders:      examples – Contains example Rifidi applications including a template to help you get started lib – Contains all the code necessary to run the Rifidi Edge Server.rifidi.

    sensorconfig/rifidi. 1.xml – a file to save reader adapter configurations logging. it prints a line that says “All Rifidi configuration paths relative to <path>”. Click Apply and Run At this point you should see log output in your console to indicate that the Edge Server has been launched.rifidi. 5. you do not use a edgeserver. Instead. you can simply right click on the class in the source code and select “Open Declaration”. 2.home’ system property. This is where the Rifidi edge server is looking for the properties listed above.rifidi. you do not need to download the source code separately to view or modify it.ini file for system properties.app. 4.template’ Select ‘Copy projects into workspace’ Click Finish Running the project Once you’ve imported the template. modify it by putting a print line in the start method so that you will see that the project is running and started. 6. At some point you should also see the debug output that you added to the template.properties – a file that controls the logging output of the edge server applications folder – contains properties for each application that starts up. This will let you view the source code for the class.rifidi. For more information see the section in this document on properties for applications When running the edge server from within eclipse. Notice that when the edge server starts up. If you want to see an entire source code plugin. 7. Now you can run the edge server from within eclipse. open the plugins view in eclipse (Window->Show View>Other->Plugins). it is configured to point to the Rifidi-SDK/RifidiHome directory. By default. Viewing and Modifying the Rifidi Source Code Because the Rifidi source code is included in the SDK as source plugins. Now right-click on the plugin that you want to view and select import as->Source Project. 3. There are two main ways to view the source code.app. Select the ‘org. but also allow you to make . put the system properties in the run configuration. You can set the path to these configuration folders using the ‘org. Open the run configuration (Run->Run Configurations) 2.5 1. This will allow you to not only view the source for the entire plugin.template’ project in the run configuration 3. File->Import Choose General->Existing Projects into Workspace Click the Browse button next to “Select root directory” Browse to the SDK directory in the workspace folder Select ‘org. Setting up Configuration Files The Rifidi Edge Server can make use of several configuration files when it starts up if they are available on the system. If your application is using a class or interface from the SDK.

a large number of which might be duplicates. and collecting EPC information. open up the run configuration. Application Engine Layer For most applications it is not desirable to save every event that the sensors produce. The Edge Server is broken up into three conceptual layers. The Application Engine Layer performs custom business processing rules on the data. Barcode readers. Mobile Devices) and collect information from them. This layer allows users to connect to devices in a sensor-agnostic way to collect the kind of data required for the application.g. Rifid Edge Server Architecture This chapter explains the architecture of the Rifidi Edge Server at a high level. Most applications are .6 changes to the source. this consists of connecting to a Gen2 fixed reader (such as Alien 9800. Many sensors can send 1. Motorolla LLRP. To run the edge server with your new changes. Sensor Abstraction Layer The purpose of the edge server is to connect to any kind of sensors (e. the edge server is designed in a way so that so that it can collect many kinds of data (active. passive. select the plugin from the workspace and deselect it from the target platform. The Communication layer (sometimes referred to as the integration layer) provides a means to integrate the business events collected in the Application layer with other systems (such as databases or ERP systems). However. etc). etc) from many kinds of devices. In many scenarios.000 of events a second. RFID readers. The Sensor Abstraction Layer provides a common API to integrate with sensors to collect various kinds of data from them.

For example. The level of configuration depends on the capabilities of the sensor and how much works has been put into the adapter. Rifidi Edge Server uses a Complex Event Processor called Esper. a stream consisting of non-persisted events) and identifying meaningful (i. and it is not desirable for the ERP system to do the work of filtering and processing all of duplicate reads the sensor produces. It does not give a step-by-step walkthrough on how to build an adapter. For example. Another application might correlate barcode reads with RFID tags and write the association to a database. Sensor Layer The sensor layer allows the edge server to connect to various kinds of sensors and collect data from them. once a sensor had been configured. In addition the sensor API’s . The applications in this layer can perform custom business logic based on the tags that are seen. For the most part. it will not change much. sensor configuration is normally handled by a technician when first setting up the sensor.e. some users might want the data to be stored in a database. aggregate and process events produced by the Sensor. as this is application dependant. it is possible to write your own connector (such as a TCP/IP socket connection) if the application needs it. the events can be of various types. However. Thus. In addition to collecting events. business) events from the stream using rules. others might want it to be pushed into an ERP system like SAP or handed to a Rich User Interface of some sort. Communication Layer After data has been processed. however. the sensor layer allows some level of sensor configuration.7 interested in events that are one-level higher than the raw events produced by sensors. it is easiest in most cases to configure the sensor using a tool provided by the sensor’s manufacturer. The sensor is either then configured to send events back to the edge server or the edge server will poll the sensor for events. an ERP system is probably interested in the event of a box arriving in area 1. The kinds of sensors can be wide ranging. one application might alert a warehouse manager via an email if a tag that matches a certain pattern is seen in a particular area. such as barcodes and GPIO events. namely JMS and Web Services (via Spring's remoting framework). An example query to get tags from a particular reader might look something like this: select * from ReadCycle where ReaderID='gate_1' The application layer lets developers write custom business logic that uses Esper to filter. from network-enabled Gen2 RFID readers to barcode scanners to JMS queues of events. The edge server has several built in connectors to use. For the vast majority of the cases. It allows you to write queries using an SQL-like syntax. In addition. For examples. it probably needs to be handed up to some kind of applicationdependent system.e. since the easiest way to learn this is by looking at the source code for adapters that ship with the Edge Server. The most common events are Gen2 RFID. Complex Event Processing (CEP) is a paradigm of viewing data as ephemeral events (i. This section describes the main components of a sensor adapter for the Rifidi Edge Server. but other event types can be collected as well.

  In addition. if you have two Alien readers. Single-Shot (or one-time) commands are intended to be executed only once. There is one SensorFactory per Sensor type. you will need to write this code yourself Will you need to poll the sensor for data. A sensor also has an ID to identify it from the OSGi command line. There is typically one SensorSession per Sensor object. Creating a New Sensor Adapter The Rifidi Edge Server ships with adapters for several popular RFID readers out of the box. you will create two Sensors. If you have two Alien readers in your infrastructure. Anatomy of a Sensor Plugin All sensors consist of three main classes:  A SensorSession class that creates a connection to the sensor and collects data from it. This chapter serves as a guide on how the various pieces of the sensor API work together. Commands interact with a sensor. There is typically one Sensor object for every physical sensor. For example. you might have two Reader IDs called Alien_1 and Alien_2. If they do not. Many sensors fall into this category. the sensor API has classes that you can extend. A SensorFactory class that creates Sensors. If you need to create a new sensor adapter. so it is recommended to look into that. Does the manufacturer provide a java API? Some sensor manufactures provide a java library that will parse and encode messages. it cannot be changed. or will the sensor be configured to automatically send back data? Will you need GPIO support? Will you need tag writing support? What kind of data will the sensor send back? The Edge Server has support for Gen2 tags and some barcodes. but if you are working with a special kind of data. For example. For example. a poll command might ask a sensor for the tags that it can currently see. there are a couple of things to consider:       What is the communication channel that the sensor uses? If it is TCP/IP or serial. The SensorFactory. Repeated commands are intended to be scheduled for repeated execution. A SensorFactory has an ID to identify it from the OSGi command line. you will use the AlienSensorFactory to create both AlienSensors. if you have two Alien readers. there is one SensorFactory for an Alien plugin. There are two types of commands. A sensor exposes connection properties (such as an IP and Port) to use when it creates a new session. There are three classes every command will need .8 source code is well documented. For example. Once a SensorSession is created. all but the most basic of sensors will have Commands. A Sensor class that creates and maintains SensorSessions. you may need to develop some classes to represent that data.

it should avoid sleeping or long running loops. From there. Sensor Sessions The Sensor Session is the most important part of a sensor adapter. CommandConfigurationFactory – A factory that produces CommandConfigurations. the Application Event Layer can process the events. 3. For example. Most barcode readers will send back the barcode that they read. it is necessary to poll the sensor to ask if it has seen any new data. Some kinds of command messages are often necessary to control the sensor. sensors that need to allow applications to access their GPIO capabilities can implement the GPIOService. the Rifidi API provides a . It is the job of the sensor session to ensure that only one command is issued at a time and to allow commands to be scheduled for repeated execution if necessary. It has three main roles: 1. the API supplies an abstract class that handles TCP/IP connections robustly (it can detect if the socket is closed and attempts to reconnect). This service allows application-level access to querying GPI state and setting GPO state. Protocol Parsing – It is the responsibility of the sensor session to parse incoming messages according to the protocol that the sensor uses. Once a command is created.   Finally. There is one factory per CommandConfiguration type. because TCP/IP is a typical protocol used for connecting to readers. It is intended that the command should execute quickly. Well written sensors sessions should normally detect when a sensor has been disconnected and attempt to reconnect if possible. it can expose properties which it uses when creating the Command. That is. The Sensor API in the Rifidi Edge Server provides several base classes that implementations can extend which handle common cases. For others. several other classes are provided that handle various kinds of connections. The end goal of a sensor session is to parse events that comes back from a sensor and put them into the Esper event engine. The Alien reader sends back clear-text strings.9  Command – The command class is a runnable which is executed by a session. 2. CommandConfiguration – The CommandConfiguration creates Commands. Command Execution – The sensor sessions have to ensure that commands issued to sensors are carried out in a thread-safe way. In addition. it cannot be changed. When developing a sensor adapter. Connection Logic – The sensor session contains the logic for connecting to and maintaining a connection with a sensor. the LLRP sensor sends back byte messages that are encoded according the LLRP specification. CommandConfigurations have IDs used for controlling them from the OSGi command line. most of the work will typically go in to protocol parsing. some sensors require a command to tell sensor to start sending back tag reads. For example. For example. since this is what varies widely from sensor to sensor. Since many applications built on top of the Rifidi Edge Server use Gen2 RFID readers. Like the Sensor.

you can inherit from AbstractSensorSession directly and rely on the manufacturer’s API to do connection logic. some sensor manufactures will provide a java jar which contains and API for connecting to their reader. For more information on this. This master-slave pattern is common and typically works out well. please see http://wiki. Instead.org/index. the Alien reader has an interactive channel on port 23. The Alien reader adapter in the edge server has one master sensor session (the interactive session ) and has two “slave” sessions (one for passively receiving tag data. You can connect to this port and send commands and receive responses. It does not contain any logic for connecting to readers. the reader might send back multiple responses or none at all). you should most likely not subclass this class directly. It will open up a socket and passively listen for a sensor to send data to it. It cannot reply back to the sensor. This logic should work for every SensorSession. and one for passively receiving GPIO data). In addition. readers that connect via TCP/IP or Serial can most likely inhert from a subclass.php/ReadCycle_Class_Hierarchy One last note on sensor session development: It is common for network-enabled readers to have one channel that is intended for interactive communication in a request-response mode. The difference between these two classes is the way in which messages from the sensor are delivered. For example. If messages are delivered asynchronously (that is for each command you send to the reader. It uses A ScheduledThreadPoolExecutor to schedule commands.10 common structure for Gen2 tag data.rifidi. If messages from the reader are delivered synchronously (that is that you expect a response for every command that you send). AbstractServerSocketSensorSession Use this class for passive TCP/IP sessions. If this API contains connection logic. Many sensor adapters will be able to make use of a subclass of AbstractSensorSession that already handles connection logic. You should only have to subclass AbstractSensorSession directly if you need your sensor communicates via some other kind of protocol. However. then use the Poll session. AbstractIPSensorSession This class handles the connection logic for a sensor which communicates via TCP/IP. . subclass either the AbstractPollIPSensorSession or the AbstractPubSubIPSensorSession class. AbstractSensorSession The AbstractSensorSession contains logic for executing commands. It can also be used to integrate hand held readers into the edge server. It is often uses for “slave” sessions such as the GPIO session for an Alien reader. For example. and one or more passive channels which the reader uses to send events on. You can then configure the reader to send back tag data and GPIO data to different ports. The following sections describe abstract classes that can be used when developing a Sensor Session class. It is used for interactive sessions (it can both send and receive messages). use the PubSub session. A handheld reader that is connected to a wifi network could just send data to the port for example.

it should not be changed. General Purpose I/O Many popular RFID readers offer General Purpose I/O capabilities. Once the session is created. There is one instance of the SensorFactory per sensor adapter type. A user can then change the port with the ‘setproperties’ OSGi console command. port. With a serial connection it is not possible to detect if a connection has been broken or not. Typically. If you type in ‘readers’ you will get a list of the sensors that have been created. and the session will resume their saved state. These properties are exposed to the OSGi command line via getter and setter methods. There is normally one Sensor instance per physical sensor device. When the edge server restarts these sensors and session will be recreated. Persistence Sensors and Sessions are persisted to an XML file when the ‘save’ OSGi command is issued. Sensors The purpose of the Sensor class is to create and maintain an immutable instance of a sensor session. Other times. the session must be destroyed. Each sensor factory has an ID that is used when creating new Sensors. the property must be changed on the sensor. Subclasses should extend AbstractSensor. and the session must be created again. These factories can create multiple instances of Sensors. For example. a reader might be configured to start reading when a photo eye detects a forklift in the near vicinity. a reader . For example. Each sensor has an ID that is used to identify it on the OSGi command line. Sensors contain connection properties (such as hostname. Sensor Factories A Sensor Factory creates instances of Sensors. etc). a sensor might have a method with this signature Public void setPort(Integer port) This sensor exposes the port property to the OSGi command line. If something needs to change on the session (such as the port that the session is connected to). Subclasses should extend AbstractSensorFactory. Using a photo eye as input is an example of GPI. a reader might want to send some output to another device based on some logic. For example.11 AbstractSerialSensorSession This sensor session uses the RXTX library to connect to a serial port. This allows the readers to interact with other devices. a sensor will have only one session. For example. there is one AlienSensorFactory and one LLRPSensorFactory available when the edge server starts up.

and integrate with existing infrastructure such as databases and JMS queues. Finally it describes some of the application that ship with the Edge Server which are useful for testing and debugging applications and sensor plugins. these classes are used to add custom Esper statements to look for events. the application can execute the proper logic based on the events that it saw in Esper. It then details the Rifid Services.12 might want to light up a green light if a box belongs in a certain area and a red light if the box does not belong there. Tag writing. This is an example of GPO. In this case. suppose different business logic should be executed depending on which photo eye saw a forklift. only the application knows if a box belongs in a certain area or not (presumably from a database look up). needs to happen in application logic. To meet this need a sensor adapter can implement the AbstractGPIOService. GPO differs from GPI in that it necessitates that the application actively controls the reader rather than passively listen for events from the reader. The application layer is intended to be general enough to support a wide variety of applications. Rifidi Application API Rifid Applications are at the heart of the Application Layer. This section starts out by taking an in-depth look at the Rifidi Application API and how to use it. In the previously mentioned green light/red light example. For more information about how to implement this. Thus an interface could be developed (similar to the AbstractGPIOService) which would allow an application to control the reader to write tags. GPIO data needs to be used in the application layer. Then. which has a few abstract methods in it that allows control over the GPIO capabilities of the reader. like turning on a GPO light. the reader should be configured to send back GPI events. subscribe to Rifidi services. . This means the application must tell the sensor to turn on a green light or a red light. Application Layer The purpose of the Sensor Layer is to collect data from sensors and put them into Esper. please see the AlienGPIOService or AwidGPIOService classes. Often. The purpose of the application layer is to perform business logic on the data that the sensors collect. For example. Tag Writing Tag writing is not currently supported by any reader. These services allow you to create applications without have to write Esper statements. and the sensor session can put the GPI events into the Esper engine. The sensor adapter and physical reader are just reporting back tags. which capture common patterns seen across many RFID applications. The sensor can then put this service into the OSGi registry. and the application can look it up and use it as it needs to. but provide some tools that are common to many applications.

api.Create the application object --> <bean id=”app1” class=”com.core.app.MyApp”/> <!-. Public class MyApp extends AbstractRifidiApp{ Public MyApp(){ super(“group”. } @Override public void _start(){ //insert code here to create esper statements or subscribe // to rifidi services } @Override public void _stop(){ //insert any clean up code here } } The second part is the Spring XML which creates the application. . deployment.edge. In addition. The first is the Application class itself. <!-. injects the application with any dependencies it requires (such as rifidi services or database connections. This xml file goes in the “META-INF/spring” folder in the bundle. and management of Rifidi Applications. “app”).rifidi. including:     Life cycle management (starting and stopping the application) Configuration management (Using property files to provide input parameters to the application) Esper management (Ensuring that Esper is used correctly) Plugging into the OSGi console (Allowing your application to be controlled by the OSGi command line) There are two pieces to every application. The required XML namespaces have been removed from the following example for the sake of brevity.register the app in the OSGi service registry --> <osgi:service ref=”app1” interface=”org.RifidiApp”/> The best way to get started with your own application is to import the Template application from the SDK and begin modifying it. all applications should extend AbstractRifidiApp. Exploring those examples are the best way to get a feel for how to code using the API. This class provides a base set of services to Rifidi Applications.mycompany. etc) and registers the application in the OSGi service registry.13 In order to provide consistent development. there are several well-documented example applications in the SDK which demonstrate many of the features of the Application API.

such as unsubscribing from Rifidi Services. The _start()method is where most of the application code belongs. For example. The AppManager automatically keeps track of any object in the OSGi registry that is exported under the RifidiApp interface. The rest of this section goes into more depth about the services offered by the AbstractRifidiApp abstract class. Open up the OSGi console and type >apps You will see a list of applications printed out.14 You can start. There are three main types of configuration files that the Application API makes available to Rifidi Apps . The Rifidi Application API gives you an easy way to do this using a standard directory structure and file-naming convention. subscribe to Rifidi Services. The AbstractRifidiApp class provides two methods for developers to override. Configuration Management One common need of many applications is to be able to externalize configuration properties to files so that they can be changed easily. It assigns this application and ID and automatically starts it if lazyStart() returns false. the Acme Corporation might have one group of applications called ‘receiving’ which handle in-bound packages. stop. When a bundle that contains one or more applications starts up. and monitor applications using the RifidiAppManager. The AppManager allows users to start and stop the applications. you can stop a started application using the stopapp command. It does this by exporting the application into the OSGi registry under the RifidiApp interface in the spring XML. Groups are logical sets of applications. add custom Esper event types. The main reason for using a group is that applications within a group can share configuration files. Each line contains     The application ID (a numeric ID) The application group The application name The state of the application (started or stopped) You can start a stopped application using the startapp command. The _stop() method is used to do any cleanup work necessary. The might have another group of applications called ‘exporting’ which handle out-bound packages. it should register its application(s) with the AppManager. Likewise. Lifecycle Management Applications can be in one of two states: started or stopped. At this point it is important to note that each Rifidi App must provide in its constructor a ‘group name’ and an ‘app name’. or do any other work that needs to be done when starting the application. It is used to add Esper statements and listeners.

App3 is in the Exporting group. the value in the application property file will be used. If it is set to false. Read zone files are stored in the readzones directory in a group directory. These are useful with Rifidi Services to determine which logical read zones a particular application is interested in. This method should be called in the initialize()method of the Rifidi App.  RifidiHome o applications  Receiving  Receiving. The directories at this level are so-called group directories. you will notice some property files. you will notice several sub directories.properties In this example. Folders are in bold and property files are in italics. In addition. Properties in this file will be shared with all applications in the group. Each group directory can contain one property file whose name is the ‘group name’ string that the applications use in their constructor. For example. Data files are stored in the data directory.properties file. there can be one property file per application.properties  App3. it defaults to false.15   Property Files follow the conventional name=value format. App2.properties  App1. Applications can both read and write these files. They share properties that are in the Receiving. the application will not be started automatically. .properties  Exporting  Exporting. App1 and App2 are both in the Receiving group. then it will be started automatically.properties  App2. They are read in when the application starts and are made available in the initialize() method. If a property is both in the group property file and the application property file. Applications can should access properties by calling the getProperty() method . These files can contain any data the application needs. The names of these directories correspond to the group names that applications provide in their constructor.  Properties If you open up the ‘applications’ directory in the ‘RifidiHome’ directory of the SDK. the Acme Corporation might use the following directory structure for their receiving and exporting applications. the Acme Corporation has two groups (Receiving and Exporting) and three applications (App1. Each of these property files will share their name with the ‘app name’ of their corresponding application. All Rifid applications use a property called LazyStart to determine if the application should be started as soon as it is loaded. Each one describes a different logical readzone. and App3). If this property is set to true. If you open up a group directory. If the LazyStart variable is not defined in a property file.

This method takes in a String which is the prefix. They start with the word ‘readzone’. These files will be read in and ReadZone objects will be automatically created. you can use the buildInsertStatement() in the EsperUtil class to build an esper statement that will insert tags into a given window that match some supplied readzones.16 Read Zones One common requirement for RFID applications is to define logical read zones for applications. turned into byte arrays and made available as a hashmap. When this method is called all data files with the given prefix are read in. Data files reside in the ‘data’ directory. it is useful for applications to read and write files.’ characters is the ID of the readzone. To this end.properties. They can be accessed using the getReadZones() method in the AbstractRifidiApp class. tagPattern – an optional regular expression defining a pattern which can be used to filter tags based on their IDs matchPattern – an optional boolean used with the tagPattern. For convenience. This ID corresponds to the Sensor ID used in the Sensor layer antennas – an optional comma-delimitated list of integers which correspond to the antennas which should be used. a particular application might only be interested in tags from antennas 1 and 2 of a certain reader. filter out tags that match the pattern The names of the readzone files follow a naming convention: readzone-[ID]. Data Files Many times. The word in between the ‘-‘ and the ‘. If set to true accept only the tags that match the pattern. Esper Management Esper is a complex event processing engine. A particular file is located from within that hashmap using its ID. which returns a HashMap where the keys are the readzone IDs and the values are ReadZone objects. you can create readzone property files in the readzones directory of a group.[suffix] They can be accessed using the getDataFiles() method . The readzone files contain the following properties:     readerID – the internal ID used to identify this reader. In addition. The App API provides a mechanism to make it easy for applications to do this. Readzones are read in when the application starts. For example. It allows users to insert events in the form of java objects into the engine and look for patterns in this data using queries. most of the Rifidi Services use ReadZone objects to define their data windows. This method will write a new file when it is called. If set to false. and they share a naming convention that is similar to the readzones: [prefix]-[id]. Files can also be written to the data directory using the writeData() method. It is a powerful tool for building RFID applications because it allows Sensors to push events into the engine and applications to state the .

it can do so using any of the addEventType() methods. However. This is handled automatically for you. In addition.   addStatement(String) is used to add a single statement to the esper runtime addStatement(String. many RFID applications have common needs. Plugging into the OSGi console The OSGi console allows users to access their application via a command line. Statements Esper’s query syntax is much like SQL. By using these methods to add statements. it allows RFID applications not to rely on databases and enables an event-driven architecture. GPIEvent. Because events are filtered in memory. If your application needs to add its own custom event type. The updateListener will allow you to handle any events which trigger the statement. The Application API helps developers keep up with two aspects of esper: statements and custom event types. TagReadEvent. they can define listeners to certain statements. such as ReadCycle. Using these methods will ensure that the Event Types are properly removed from the runtime when your application stops. Rifidi Services Esper is a powerful tool for building RFID applications. the Abstract Rifidi App provides two methods that should be used when adding statements and listeners. the Rifidi Edge Server offers ‘Rifidi Services’ which capture a few common . there is no need to remove the statements when your application stops. Applications can add these Esper ‘statements’ to the Esper runtime. Please see the Esper documentation about how to access properties from these events in statements. It is often useful for administration and testing purposes. There are two types of events: Java objects and Map events. Because it is important to keep up with which statements have been added and to make sure statements are removed when the application starts up.17 patterns they are looking for. Each application can contribute to the console by overriding the getCommandProvider() method. Please consult the Esper documentation online for information about esper syntax and semantics. Then applications are notified when an event happens that match the pattern. Contributing an object that implements the CommandProvider interface will allow the application to expose its own commands on the OSGi command line. Custom Event Types The Esper runtime must know ahead of time what kind of events will be put into it.StatementAwareUpdateListener) is used to add a statement and a listener to that statement. The Rifidi Edge Server has several kinds of events already defined in the Esper runtime that every application can make use of. and GPOEvent. For these scenarios.

edge.app.rifidi. subscribe to the service passing in the subscriber and any parameters needed. unsubscribe from the service.service. In general. Read Zone Monitoring Service The Read Zone Monitoring service notifies subscribers when a tag enters a particular readzone and when it leaves a read zone.tagmonitor. You put all the tags in the field of view of an antenna. To subscribe to this service.core. which gives you the following method: stableSetReached(Set<TagReadEvent> stableSet) Unique Tag Batch Interval Service The Unique Tag Batch Interval Service periodically notifies subscribers of unique tags that have been seen in the read zone since the last notification. and you want to be able to process all the tags seen as a group. In the _stop() method for your application.edge. In the _start() for your application.ReadZoneMonitoringService”/> You should implement the ReadZoneSubscriber interface.StableSetService”/> You should implement the StableSetSubscriber interface. This pattern is often useful when there is a concept of children tags and a parent tag. put the following in your spring. For example.rifidi. In your application. which gives you two methods: tagArrived(TagReadEvent tag) tagDeparted(TagReadEvent tag) Stable Set Service The Stable Set Service notifies subscribers when a given amount of time has passed without any new tags having arrived. to subscribe to a service you need to follow these steps: 1. . 4. implement the appropriate subscriber interface 3. In the spring xml for the application.tagmonitor.service.app. It then passes all the tags seen in that interval to the listener.xml file: <osgi:reference id=”ReadZoneService” interface=”org.xml file <osgi:reference id=”StableSetService” interface=”org.api.api. Inject it into your application 2. put the following in your spring. get a hold of the service that you want to subscribe to. imagine that you want to group items to a container. To subscribe to this service.core.18 RFID use cases and allow your application to subscribe to these patterns without the need to write custom Esper statements.

tagmonitor.service. put the following in your spring. which gives you the following method: handleSensorStatusEvent(SensorStatusEvent event) Diagnostic Applications The Rifidi Edge Server platform ships with several applications designed to help gather information some diagnostic information and to help developers and administrators troubleshoot common problems.app. it notifies subscribers about changes to the sensor layer. put the following in your spring.core.UniqueTagIntervalService”/> You should implement the UniqueTagIntervalSubscriber interface.rifidi. GPIO The GPIO application allows users to interact with GPIO devices (as long as the reader and Rifidi Edge Server reader adapter support GPIO).xml file <osgi:reference id=”UniqueTagBatchIntervalService” interface=”org. To subscribe to this service.core. which gives you the following method: tagSeen(TagReadEvent tags) Sensor Status Monitoring Service This service is slightly different from the others mentioned so far.service.api.core.api. put the following in your spring.edge. It’s useful for giving your application access to when Sensor connect or disconnect.rifidi. Instead of notifying subscribers about Tag events that happen.rifidi.service.tagmonitor.sensormonitor.UniqueTagBatchIntervalService”/> You should implement the UniqueTagBatchIntervalSubscriber interface. See the help menu on the OSGi console for correct usage of these commands.edge.19 To subscribe to this service.app.xml file <osgi:reference id=”UniqueTagIntervalService” interface=”org.edge.SensorStatusMonitoringService”/> You should implement the SensorStatusSubcriber interface. which gives you the following method: tagBatchSeen(Set<TagReadEvent> tags) Unique Tag Interval Service The Unique Tag Interval Service notifies you the first time a unique tags is seen at a read zone and periodically after that if the tag is still in the read zone.api.app.xml file <osgi:reference id=”SensorSubscriberService” interface=”org. . To subscribe to this service.

properties – this file controls how the tags will be exposed to Esper. there are a few commands which “simulate” GPI events by inserting fake GPI events into the esper runtime. This is useful for testing and troubleshooting applications which rely on GPI events from a reader to operate without having to actually have the hardware hooked up. it controls the rate at which tags are exposed and triggers to stop exposing them tags-<ID>.     simGPIHigh – sends a GPI High event into Esper simGPILow – sends a GPI Low event into Esper simGPIFlashHigh – sends a GPI high event and then a GPI low event into Esper simGPIFlashLow – sends a GPI Low event and then a GPI High event into esper Serial The serial application exposes several commands that help you determine which serial ports are available on your machine. use this command: > startTagRunner <tagFileID> <exposureFileID> .txt – This file contains the tags to expose along with which reader and antenna In order to initiate the fake tag reads. It works using a set of two property files.Returns the current GPI state on a reader setGPO – Sets a GPO state on a reader flashGPO – Changes a GPO state on a reader for a certain amount of time In addition.lists the tags that the edge server has seen recently tagrate . both located in the RifidiHome/applications/Diagnostic/data directory.   exposure-<ID>.20    testGPI . It is useful when developing and testing applications so that you don’t have to have real hardware hooked up to your system to send tags events into the reader. For example. This is often useful when configuring a reader adapter which uses a serial protocol.    currenttags – lists the tags that the edge server can currently see recenttags .lists the number of tags per second that the edge server is current seeing Tag Generator This utility allows developers to send ‘fake’ tag events into Esper.    connectSerial – connect to a certain serial port disconnectSerial – disconnect from a certain serial port listSerial – List all serial ports available on your machine Tags The tags application allows developers and to gather some information about the tags that the edge server is gathering.

Indicates how many tags per second we should expose to esper groupSize: Used with ‘delay’ exposureType.count: A count-based stop trigger. Indicates number of milliseconds to pause in between exposing a group. you can use many spring technologies inside of the Rifidi Edge Server.       Tag Files Tag files simply contain the data to expose. The exposure will stop running after the defined number of tags have been exposed. and the antenna ID.21 Exposures Files There are several properties in an exposure file that control how tags are exposed  exposureType: There are two basic types of exposures: ‘rate’ and ‘delay’. delay: Used with ‘delay’ exposureType. A ‘rate’ type means that the exposure will attempt to put tags into esper according to a given rate.springframework. The exposure will stop running after the defined number of milliseconds random: If true. You can get a hold of it in spring with the following code: <osgi:reference id=”externalJMSTemplate” interface=”org.core. Indicates how many tags should be exposed at once.xml file. the exposure will pick tags from the tag file at random tagRate: Used with ‘rate’ exposureType. The integration layer is heavily spring based. and in general. the readerID. JMS The Rifidi Edge Server runs an embedded ActiveMQ broker. The Rifidi Edge Server provides several methods of integration out of the box. The following section lists a few of many possible integration technologies. Each tag is on a new line.JmsTempalte” beanname=”externalJMSTemplate”/> . there is already a preconfigured spring JMSTemplate that you can use to send out messages. Integration Layer Once applications have identified the business events they are interested in. Each line has three commaseparated fields: the tagID. stop. In addition. A ‘delay’ means that the exposure will expose a defined number of tags with a given delay in between each cycle. stop.jms. they will want to integrate with existing systems.time: A time-based stop trigger. You can change the ActiveMQ’s settings in by editing the config/rifidi-amq.

rifidi. Please see Spring’s documentation for details.edge. Please refer to Spring’s JaxWsServiceExporter for details on how to use this.JaxWsServiceExporter" init-method="start" destroy-method="stop"> <property name="port" value="8080/> <property name="host" value="http://localhost" /> <property name="deploy" value="true" /> <property name="service" ref="beanID" /> </bean> Exporting and Deploying Once your application is built and tested.utilities. you can useRifidi’s JaxWsServiceExporter. Place the jar and xml file into the application’s group folder.derby. RMI You can use Spring’s RMIServiceExporter to expose an interface over RMI. you can extend Rifidi’s AbstractDBDAO class which might provide a useful interface for some use cases. you will want to export it so that it can run on an instance of the edge server.create=true In addition. add the name of the group folder to the default.core. In order deploy the application there are a few steps you need to follow: 1. The following shows how to use the service in spring. Run the bindex utility on them in order to generate a repository.jdbc. The database starts up when the edge server starts. <bean id="LRWebServiceDeployer" class="org. If you want the application to start immediately.22 Databases Out of the box.EmbeddedDriver url=jdbc:derby:DB_NAME. the Rifidi Edge Server ships with Derby – an embeddable database . 3. The connection properties you need are driverClassName=org.ini file in the applications directory. Please note that the ‘service’ property refers to a bean that has the @WebService annotation.xml file that is used when dynamically loading your bundle. One way to access it is using Spring’s JDBCTemplate. This is an example of the directory structure for an application whose group is ‘Acme’ and whose application name is ‘Shipping’  RifidiHome . Webservice If you have a service that you want to expose as a WebService.apache. 4. Please see spring’s documentation on how to use the JDBCTempalte. Export the projects as OSGi bundles out of eclipse 2.

rifidi. the packages would be sent out for shipping. a tag moves from the dock door to the weigh station. 1.php/How_to_export_your_custom_Rifidi_application Example: Northwind Congratulations! You are the proud new founder of Northwind Shipping Inc. -. Northwind Business Rules The Northwind distribution center's current process looks like this: 1..xml You can find more information about this topic on our wiki http://wiki. and do extra processing based on what happens when it enters and leaves an area. tags are seen with their forklift tag. 3. RFID can add value to this workflow by monitoring whenever a tag enters or leaves an area (either the dock door or the weigh station). a tag enters or leaves an area.properties  Shipping.org/index. From the dock door. You have heard all the hype about RFID and want to employ in it your new. state-of-the-art distribution center. This tutorial will show you how to set up an application and use all the various features provided by the Rifidi Edge application API. Occasionally. an inventory is taken. The forklift will then take the packages to a weigh station. . Error messages should be printed if. One of your core business strategies is to out perform your competitor -."delivering packages faster than a caffeinated lightning bug"™.23 o applications  Acme  plugins o acme.by capitalizing on increased efficiencies gained by your innovative use of technology..Pony Express Shipping Inc. 2. which are transported via forklift (also outfitted with RFID tags) to a dock door. -.properties  repository. After the weigh station. something can go wrong and an item will do something unexpected. 3. A message should be printed when.. Boxes (fitted with RFID tags) are loaded onto a pallet. where the packages would be weighed.. 2.jar  Acme. You have decided to use the Rifidi Edge Server to run the RFID applications you will need in your distribution center.

If you want. and open the “Northwind. Delete all the tags from the field of view. You might need to adjust the names of the readers for the dock door and weigh station. Move the same 3 tags onto the weigh station reader. and an already set up weigh station reader (127. stop the edge server and open the org.northwind plugin.0. Item tags are seen without an accompanying forklift tag. Tags are seen on the weigh station which was not seen at the dock door. you can use any physical readers you have access to.edge.edge. You should see 3 “tag arrived” messages for the dock door. you can use the included Prototyper file with an already set up dock door reader (127. stating that the tag moved backwards. This shows all of the properties that can be adjusted for this application (see the application documentation for more on the properties files).1:20000). Select the package “org. 2. Press “Apply”. If you don't see the Northwind app at all. or you can use Emulator to create the readers of your choice and then use edge to connect to them. After the properties files are set up correctly. as well as the Setting up and running the Northwind Example 1. If you see it but it is stopped. 3. 5.0. 3. More documentation on how this was accomplished is given in the Esper documentation. Import the plugin from the “examples” directory in the SDK plugin. run the program and create the readers you want to use. You should get 3 “tag departed” messages for the dock door.rifidi. If you like. Copy the “Northwind” folder and paste it into the “Rifidi-SDK/RifidiHome/applications” folder. 4. as well as 3 events telling you that the tags have moved from the dock door .rifidi. Type in “apps” and make sure the Northwind Application has started. you can begin adding and removing tags from the field of view of the readers. plus a message telling you that a forklift was seen with the other tags. 3.northwind” in the “bundles” tab. make sure the plugin is set to Auto-Start in the run configuration. Here is a sample of what you can do: 1. 2. Go to Run > Run Configurations and click on “Edge Server” under “OSGi Framework” on the left. you will have to manually start it. You should see 3 “tag arrived” events for the weigh station. depending on what the names of the readers are in Rifidi Edge. Tags move from the weigh station to the dock door. 4.0. Create 1 GID tag and 2 SSCC tags (this assumes that the “ForkliftPrefix” property is set to the default “35”). A more thorough explanation of each of the properties is in the file itself.1:30000). After you know the application is working. move all 3 tags into the field of view of the Dock Door reader. Set up the eclipse workspace and import the SDK. 4. As a group. After you have connected to the readers set in the Northwind properties file. 2. Then open the folder. Now either close and run the “Edge Server” launch framework or just press “run”.24 1.properties” file.0. Check the Applications section of the documentation for more help debugging problems starting applications. The properties files for both the dock door and weigh station ReadZones are also in this folder.

properties.rifidi. and all of the logic is implemented.php?f=35 . 3. Subscribers. check their respective files. only some of the rules were used for it. Invoking the rules given above on your own. The other is a StableSetSubscriber that will look for forklift tags and print output depending if a forklift is present when tags are read. 2.app. They contain no information except for the ID of the tag that they represent. Northwind Application Architecture The Northwind application contains three parts: 1. Setting up the ReadZones. as well as studying the Esper used to create these rules will help you greatly when you are writing your own application. should you need more examples. The Northwind files themselves are well-commented. Other application plugins.edge. and Esper all happens in this class. which will subscribe to ReadZones that we create and fire events based on certain criteria. The application class: NorthwindApp. if you need any more help with your application. The subscriber classes: These classes represent two different kinds of subscriber: one is a regular ReadZoneSubscriber. For more information on how these classes work. This is only one example of what you can do.25 to the weigh station.org/viewforum.diag) should give you more examples of what you can do with applications. Finally. but any events you make can contain any information. You should also get output telling you that a forklift was seen. such as the diagnostic tools (org. Check out the file itself for a more detailed explanation of how the application works. and should help you get a better understanding of how applications are built and run. The event classes: These are simply shell classes that are created to be passed into Esper.java is where the program is set up. go to our forums: http://forums.rifidi.