{"id":64,"date":"2015-12-07T19:56:07","date_gmt":"2015-12-08T00:56:07","guid":{"rendered":"http:\/\/jsevy.com\/wordpress\/?page_id=64"},"modified":"2015-12-07T20:43:43","modified_gmt":"2015-12-08T01:43:43","slug":"snmp-package-introduction","status":"publish","type":"page","link":"https:\/\/jsevy.com\/wordpress\/index.php\/java-and-android\/snmp\/snmp-package-introduction\/","title":{"rendered":"Java SNMP Package Introduction"},"content":{"rendered":"

This provides an introduction to the Java SNMP package<\/a> , an open-source implementation of the SNMP protocol in a Java package. It provides support for basic SNMP client operations as defined in SNMP versions 1 and 2 (excluding the security model proposed as part of SNMP version 2, which was never widely accept or deployed). The package provides a mechanism for “getting and setting” SNMP object identifier (OID) values through a simple communication interface, and represents SNMP structures and datatypes as corresponding Java objects. The package assumes familiarity with the SNMP protocol as detailed in RFC’s 1157, 1155, 1212, etc.; however, some simple examples are provided which illustrate its use for simple get\/set operations (though a knowledge of the concepts of OIDs and SNMP datatypes is still required).<\/p>\n

The complete API documentation for the package is provided through JavaDoc documentation <\/a>. This introduction is intended to provide an overview of the package, with particular focus on the classes an end user will need to directly interface with to incorporate the package into a project.<\/p>\n

Main Interface: the SNMPv1CommunicationInterface Class<\/h2>\n

Much of the top-level user functionality is provided by the class SNMPv1CommunicationInterface. This constructor for this class opens a datagram socket to a specified host for SNMP communication on the standard port (192). Several methods of the class then provide a means to retrieve and set the value of SNMP variables on the remote device by supplying a string specifying an object identifier and an appropriate SNMP object for set operations. The example program listed below illustrates the use of the communication interface class to open a connection to a remote device, get the value of two variables corresponding to OIDs 1.3.6.1.2.1.1.1.0 and 1.3.6.1.2.1.1.3.0, and set the value of a third variable. The source code for the SNMP Inquisitor (included in the Java SNMP package<\/a> source distribution) shows the use of the package in a general-purpose utility which permits SNMP querying and modification of a remote device.<\/p>\n

The constructor for the SNMPv1CommunicationInterface takes three parameters: an integer giving the SNMP version in use (generally always 0), the remote device address supplied as an InetAddress object, and a string giving the SNMP community to be used for the operations.<\/p>\n

Getting and Setting Variable Values<\/h3>\n

Once the communication interface has been created to communicate with a device, the values of SNMP variables can be retrieved with calls to the getMIBEntry( ) method. This takes as argument a string with the variable’s OID; the return value is somewhat complex, due to SNMP’s ability to query multiple variables in a single message (though this particular method retrieves only one value at a time) and to support the getNextMIBEntry( ) method (describesd below). The return value is of type SNMPVarBindList, a subclass of SNMPSequence which holds a sequence of (OID, value) pairs. Thus the retrieved SNMP value is accessed as follows:<\/p>\n