Removing User name or Password The first time you run a JXTA application, you will be prompted to enter a user name and password. Each subsequent time you run the application, you will be prompted to enter the same user name and password pair. If you forget either the user name or the password, you can remove the cm directory (located in the under $JXTAHOME directory, by default .jxta) and then re-run the application. The JXTA Configurator will be displayed, and you can enter a new user name and password. See http://wiki.java.net/bin/view/Jxta/WebHome for more details on running the JXTA Configurator. 147 JXTA v2.3.x: Java Programmer s Guide
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Starting from a clean state Some problems can be caused by stale configuration or cache information. Try removing the JXTA configuration files and cache directory: n ./.jxta/PlatformConfig n ./.jxta/cm (directory) Re-launch the application. When the Configuration window appears, enter the appropriate information for your network configuration. See http://platform.jxta.org/java/confighelp.html for more details on running the JXTA Configurator. Displaying additional log information If your JXTA application isn t behaving as you expect, you can turn on additional logging so that more information is displayed when your application runs. To select a new logging, or trace, level, re-run the JXTAConfigurator and from the Advanced Settings tab select the desired Trace Level from the pull-down menu. The default trace level is error; warn, info, and debug levels provide more information. For more information on running the JXTA Configurator, please see Appendix , Emphasisparatextefault . You can also choose to edit the PlatformConfig file in the current directory rather than rerunning the JXTA Configurator. For example, the following entry in PlatformConfig sets the trace level to “warning”: warn 146 JXTA v2.3.x: Java Programmer s Guide
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Troubleshooting This appendix discusses commonly encountered problems compiling and running JXTAapplications. Errors compiling JXTA applications Check that your are including the correct jxta.jar file in your compilation statement (-classpath option). If you have downloaded multiple versions, verify that you are including the most recent version in your compilation statement. Note The required .jar files can be downloaded from the JXTA Web site: http://download.jxta.org. Errors running JXTAapplications Setting the classpath variable When you run your JXTAapplication, you need to set the -classpath variable to indicate the location of the required .jar files. Be sure to include the same version that you used when compiling your JXTAapplication. Although you need only the jxta.jar file for compilation, you need multiple .jar files when running a JXTAapplication. Note See on page for a list of the required Java .jar files. Unable to discover JXTA peers If you are unable to discover other JXTA resources (peers, peer groups, or other advertisements), you may have configured your JXTA environment incorrectly. Common configuration issues include the following: If you are located behind a firewall or NAT, you must use HTTP and specify a relay node. If you are using TCP with NAT, you may need to specify your NAT public address. You may need to specify at least one rendezvous node. Remove the JXTA configuration file (PlatformConfig) and then re-run your application. When the JXTAConfigurator window appears, enter your configuration information. See Appendix , for more details on running the JXTA Configurator. Using the JXTA Shell You can use the JXTAShell to help troubleshoot configuration issues and test JXTAservices. Commands are available to discover JXTA advertisements, create JXTA resources (e.g., groups, pipes, messages, and advertisements), join and leave peer groups, send and receive messages on a pipe, and much more. For example, to verify correct network configuration you can use the JXTAShell command “rdvstatus” to display information about your current rendezvous status (i.e., if you are configured as a rendezvous peer, and who your current rendezvous peers are). You can also use “search -r” to send out discovery requests, and then use “peers” to display any peers that have been discovered to confirm that network connectivity is working as expected. For more information on downloading and using the JXTAShell, please see: http://shell.jxta.org/ 145 JXTA v2.3.x: Java Programmer s Guide
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Peer Information Protocol; used by peers to obtain status information (uptime, state, recent traffic, etc.) from other peers. Pipe An asynchronous and unidirectional message transfer mechanism used by peers to send and receive messages; pipes are bound to specific peer endpoints, such as a TCP port and associated IP address. Pipe Endpoint Pipe endpoints are referred to as input pipes and output pipes; they are bound to peer endpoints at runtime. PKI Public Key Infrastructure. Supports digital signatures and other public key-enabled security services. PRP Peer Resolver Protocol; used by peers to send generic queries to other peer services and receive replies. Relay Peer Maintains information on routes to other peers, and helps relay messages to peers. (Previously referred to as router peer.) Rendezvous Peer Maintains a cache of advertisements and forwards discovery requests to other rendezvous peers to help peers discover resources. RVP Rendezvous Protocol; responsible for propagating messages within a peer group. TLS Transport Layer Security. (See http://www.ietf.org/html.charters/tls-charter.html for more details.) URI Uniform Resource Identifier. A compact string of characters for identifying an abstract or physical resource. (See http://www.w3.org/Addressing/URL/ URI_Overview.html for more details.) URN Uniform Resource Name. A kind of URI that provides persistent identifiers for information resources. (See IETF RFC 2141, http://www.ietf.org/rfc/rfc2141.txt, for more details.) 144 JXTA v2.3.x: Java Programmer s Guide
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Module Implementation The implementation of a given module specification; there may be multiple module implementations for a given module specification. Module Specification Describes a specification of a given module class; it is one approach to providing the functionality that a module class implies. There can be multiple module specifications for a given module class. The module specification is primarily used to access a module. NAT Network Address Translation. Network Address Translation allows a single device, such as a router, to act as an agent between the Internet (or public network ) and a local (or private ) network. Output Pipe A pipe endpoint; the sending end of a pipe. Pipe endpoints are dynamically bound to peer endpoints at runtime. P2P Peer-to-peer; a decentralized networking paradigm in which distributed nodes, or peers, communicate and work collaboratively to provide services. PBP Peer Binding Protocol; used by peers to establish a virtual communication channel, or pipe, between one or more peers. PDP Peer Discovery Protocol; used by peers to discover resources from other peers. Peer Any networked device that implements one or more of the JXTA protocols. Peer Endpoint A URI that uniquely identifies a peer network interface (e.g., a TCP port and associated IP address). Peer Group A collection of peers that have a common set of interests and have agreed upon a common set of services. Peer Group ID ID that uniquely identifies a peer group. Peer ID ID that uniquely identifies a peer. PIP 143 JXTA v2.3.x: Java Programmer s Guide
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Advertisement Project JXTA s language-neutral meta-data structures that describe peer resources such as peers, peer groups, pipes, and services. Advertisements are represented as XML documents. ASN.1 Abstract Syntax Notation One; a formal language for abstractly describing messages sent over a network. (See http://www.asn1.org/ for more information.) Binding An implementation of the Project JXTAprotocols for a particular environment (e.g., the J2SE platform binding). Credential A token used to uniquely identify the sender of a message; can be used to provide message authorization. Endpoint See Peer Endpoint and Pipe Endpoint. ERP Endpoint Routing Protocol; used by peers to find routes to other peers. Gateway See Relay Peer. Input Pipe A pipe endpoint; the receiving end of a pipe. Pipe endpoints are dynamically bound to peer endpoints at runtime. J2SE Java 2 Platform, Standard Edition software. Message The basic unit of data exchange between peers; each message contains an ordered sequence of named sub-sections, called message elements, which can hold any form of data. Messages are exchanged by the Pipe Service and the Endpoint Service. Message Element A named and typed component of a message (i.e., a name/value pair). Module An abstraction used to represent any piece of “code” used to implement a behavior in the JXTA world. Network services are the mode common example of behavior that can be instantiated on a peer. Module Class 141 JXTA v2.3.x: Java Programmer s Guide
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Represents an expected behavior and an expected binding to support the module; is used primarily to advertise the existence of a behavior. 142 JXTA v2.3.x: Java Programmer s Guide
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Glossary 140 JXTA v2.3.x: Java Programmer s Guide
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try { myNetPeerGroup=PeerGroupFactory.newNetPeerGroup(); } catch ( PeerGroupException e) { // could not instantiate the group, print the stack and exit System.out.println(”fatal error : group creation failure”); e.printStackTrace(); System.exit(1); } return myNetPeerGroup; } public static void main(String args[]) { SecurePeerGroup satellaRoot = new SecurePeerGroup(); System.exit(0); } } 138 JXTA v2.3.x: Java Programmer s Guide
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Chapter 8: References The following Web pages contain information on Project JXTA: http://www.jxta.org home Web page for Project JXTA http://spec.jxta.org Project JXTA specification http://platform.jxta.org Project JXTAplatform infrastructure and protocols for the J2SE platform binding http://platform.jxta.org/java/api/overview-tree.html public API (Javadoc software) http://www.jxta.org/Tutorials.html numerous Java tutorials There are numerous technical white papers posted on http://www.jxta.org/white_papers.html. Those of particular interest to developers include: Project JXTA: An Open, Innovative Collaboration, Sun Microsystems white paper. Project JXTA: A Technology Overview, Li Gong, Sun Microsystems white paper. Project JXTA Technology: Creating Connected Communities, Sun Microsystems white paper. Project JXTA Virtual Network, Bernard Traversat et al., Sun Microsystems white paper. Project JXTA: A Loosely-Consistent DHT Rendezvous Walker, Bernard Traversat, Mohamed Abdelaziz, and Eric Pouyoul, Sun Microsystems white paper. Introduction to the JXTAAbstraction Layer, Neelakanth Nadgir and Jerome Verbeke, Sun Microsystems. PKI Security for JXTA Overlay Networks, Jeffrey Eric Altman, IAM Consulting. 139 JXTA v2.3.x: Java Programmer s Guide
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