[AGENT++] Multiple SNMP agents in single application

[Claus Klein]

Hi Frank,

Thank for feedback. I will try to use it.

For snmp StorageTable's, I changed the templates to generate code like  
that:

class NET_SNMP_EXAMPLES_MIB_DECL netSnmpHostsEntry: public StorageTable
{

public:
	netSnmpHostsEntry(const NS_SNMP OctetStr& context);
	virtual ~netSnmpHostsEntry();

	static netSnmpHostsEntry* instance;

     typedef std::map<std::string, netSnmpHostsEntry*>  
netSnmpHostsEntryMap_t;
     static netSnmpHostsEntryMap_t contextmap;
private:
     std::string mycontext;
public:

	virtual void        	get_request(Request*, int);
	virtual int         	commit_set_request(Request*, int);
	virtual int         	prepare_set_request(Request*, int&);
	virtual void        	cleanup_set_request(Request*, int&);
	virtual int         	undo_set_request(Request*, int&);
	virtual void        	row_added(MibTableRow*, const Oidx&, MibTable*);
	virtual void        	row_delete(MibTableRow*, const Oidx&, MibTable*);
	virtual void        	row_init(MibTableRow*, const Oidx&, MibTable*);
	virtual void        	row_activated(MibTableRow*, const Oidx&,  
MibTable*);
	virtual void        	row_deactivated(MibTableRow*, const Oidx&,  
MibTable*);
	virtual void        	update(Request*);
	virtual int         	is_transition_ok(MibTable*, MibTableRow*, const  
Oidx&, int, int);
	virtual void		set_row(MibTableRow* r,
						        long p1,
						        const NS_SNMP OctetStr& p2,
						        long p3,
						        long p4);
//--AgentGen BEGIN=netSnmpHostsEntry
     void change_notification(const Oidx& id, mib_change what);
//--AgentGen END
};


/**
  *  netSnmpHostsEntry
  *
  * "A host name mapped to an ip address"
  */

netSnmpHostsEntry* netSnmpHostsEntry::instance = 0;
netSnmpHostsEntry::netSnmpHostsEntryMap_t netSnmpHostsEntry::contextmap;

const index_info indNetSnmpHostsEntry[1] = {
	{ sNMP_SYNTAX_OCTETS, FALSE, 0, 64 }
};

netSnmpHostsEntry::netSnmpHostsEntry(const NS_SNMP OctetStr& context):
    StorageTable(oidNetSnmpHostsEntry, indNetSnmpHostsEntry, 1)
{
	// This table object is a singleton. In order to access it use
	// the static pointer netSnmpHostsEntry::instance.
	instance = this;
     mycontext = context.get_printable();
     // add this context to the context map
     contextmap[context.get_printable()] = this;

	add_col(new netSnmpHostAddressType(colNetSnmpHostAddressType));
	add_col(new netSnmpHostAddress(colNetSnmpHostAddress));
	add_storage_col(new netSnmpHostStorage(colNetSnmpHostStorage));
	add_col(new netSnmpHostRowStatus(colNetSnmpHostRowStatus));
	//--AgentGen BEGIN=netSnmpHostsEntry::netSnmpHostsEntry

//NOTE: this mib supports to be instantiated multiple times with  
different context

	//--AgentGen END
}

netSnmpHostsEntry::~netSnmpHostsEntry()
{
	//--AgentGen BEGIN=netSnmpHostsEntry::~netSnmpHostsEntry
	//--AgentGen END
	// clear singleton reference
	netSnmpHostsEntry::instance = 0;
     // erase this context from context map
     contextmap.erase(mycontext);

}

#################################################

I use a static contextmap instead the static instance ptr. where I  
need more than instance of that table with different context values.

What do you mean about that idea?


Regards,
Claus


On 12.03.2013, at 19:55, Frank Fock wrote:

> Hi Claus,
>
> Within the standard constructor, you cannot know the context. This  
> is a limitation of
> the AGENT++ design (I solved that better with SNMP4J-Agent).
>
> Nevertheless, there is a workaround. Subclass MibLeaf with your own  
> class.
> That class can be generic and with the AgenPro 'leafSuperClass'  
> property
> you can then generate each class to use that super class instead of  
> MibLeaf.
> The constructor of that super class then takes the context as  
> additional parameter.
>
> If your code can be reorganized to use context information only at  
> "runtime"
> when Requests are processed, then it would be easy to get the context
> information from the Request.
>
> Best regards,
> Frank
>
> Am 12.03.2013 06:10, schrieb Claus Klein:
>> Hi,
>>
>> there are 2 little unresolved problems with the same mib under  
>> different context values.
>> How to get the context value and how to work with this static  
>> instance variable:
>>
>> netSnmpExampleInteger::netSnmpExampleInteger():
>>   MibLeaf(oidNetSnmpExampleInteger, READWRITE, new NS_SNMP  
>> SnmpInt32(42), (VMODE_LOCKED | VMODE_DEFAULT)) {
>>   // This leaf object is a singleton. In order to access it use
>>   // the static pointer netSnmpExampleInteger::instance.
>>   instance = this;
>>   //--AgentGen BEGIN=netSnmpExampleInteger::netSnmpExampleInteger
>>   //FIXME how to get mycontext?
>>   //XXX if (netSnmpHostsEntry::contextmap[mycontext])
>>   if (netSnmpHostsEntry::instance) {
>>       // NOTE register a call of  
>> netSnmpExampleInteger::change_notification()
>> netSnmpHostsEntry::instance->register_for_notifications(this);
>>   }
>>   //--AgentGen END
>> }
>>
>> On 08.03.2013, at 21:14, Jochen Katz wrote:
>>
>>> Hi,
>>>
>>>> I need to host the same MIB at multiple ports within a single  
>>>> application.
>>>> Each hosted MIB (at a different port) will end up accessing  
>>>> different data
>>>> within the application.
>>>>
>>>> Can I do this within agent++/snmp++? If so, how? I see that  
>>>> instances are
>>>> used for each MIB object, so I am unsure how I can have a single  
>>>> MIB that
>>>> is hosted multiple times access different data within a single  
>>>> application.
>>>
>>> there can only be one instance of agent++ Mib class in an  
>>> application
>>> and the same is true for other classes of agent++/snmp++.
>>>
>>> You can add your MIB objects for several contexts and then either  
>>> use
>>> SNMPv3 with different contextEngineIDs or map several SNMPv1/v2c
>>> communities to the different contexts.
>>>
>>> Regards,
>>> Jochen
>>> _______________________________________________
>>> AGENTPP mailing list
>>> AGENTPP at agentpp.org
>>> http://lists.agentpp.org/mailman/listinfo/agentpp
>>
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