I am working on code which uses the snmp->get_bulk_request() method to make SNMP queries to get interface table details from a network device.
The problem I am facing is that sometimes, the data I receive from the query is missing some detail. This is a transient issue.
I believe that placing a set number of retries will reduce the probability of error. But, as I go through the documentation for snmp->get_bulk_request(), I find a parameter called
maxrepetitions. It is not clear to me from the documentation what this parameter does.
I am trying to figure out what effect the maxrepetitions parameter has when used with the get_bulk_request call method. I have gone through the documentation in "get_bulk_request() - send a SNMP get-bulk-request to the remote agent" and found this:
$result = $session->get_bulk_request(
[-callback => sub {},] # non-blocking
[-delay => $seconds,] # non-blocking
[-contextengineid => $engine_id,] # v3
[-contextname => $name,] # v3
[-nonrepeaters => $non_reps,]
[-maxrepetitions => $max_reps,]
-varbindlist => \#oids,
);
The default value for get-bulk-request -maxrepetitions is 0. The maxrepetitions value specifies the number of successors to be returned for the remaining variables in the variable-bindings list.
Specifically, my questions are:
Is adding maxrepetitions equivalent to adding retries for the query?.
Is retrying the right way to ensure the data is most probably correct?
If not, what is the best method to ensure the probability error is low in data returned by SNMP query?
From the man page:
Set the max-repetitions field in the GETBULK PDU. This specifies the maximum number of iterations over the repeating
variables.
Example
snmpbulkget -v2c -Cn1 -Cr5 -Os -c public zeus system ifTable
will retrieve the variable system.sysDescr.0 (which is the lexicographically next object to system) and the first 5 objects in
the ifTable:
sysDescr.0 = STRING: "SunOS zeus.net.cmu.edu 4.1.3_U1 1 sun4m"
ifIndex.1 = INTEGER: 1
ifIndex.2 = INTEGER: 2
ifDescr.1 = STRING: "lo0"
et cetera.
Related
I have a couple scenarios where a series of arbitrary string values have a specific priority sequence. For example:
forgo > log > assert
exception > failure > error > warning > alert
And, I need to evaluate an arbitrary number of scenarios that resolve to one of those values and maintain a running status. So, using the simpler example, if every evaluation is assert then the final running status would be assert. But if a single evaluation is log and the rest are assert, the the final running status is log. And a single forgo means the final status is forgo, no matter what the mix of individual status results was. I want to provide a human readable running status and individual status, do the math to determine what the new running index is, then return the human readable status.
So, I have this, and it works.
$statusIndex = #('assert', 'log', 'forgo')
$runningStatus = 'forgo'
$individualStatus = 'log'
$runningStatusIndex = $statusIndex.indexof($runningStatus)
$individualStatusIndex = $statusIndex.indexof($individualStatus)
if ($individualStatusIndex -gt $runningStatusIndex) {
$runningStatusIndex = $individualStatusIndex
}
$runningStatus = $statusIndex[$runningStatusIndex]
But, this feels like something that happens often enough that there may be a more "native" way to do it. Some built in PowerShell functionality that handles the same thing more elegantly and in less code.
Is my intuition correct, and there is a native way? Or, perhaps a more elegant approach than what I have here?
Put your terms in an array, in precedence order:
$statusIndex = #('forgo', 'log', 'assert')
Aggregate all your status values and remove any duplicates:
$statusValues = 'assert', 'assert', 'log', 'assert'
$statusValueSet = $statusValues |Sort -Unique
Now use the .Where() extension method to select only the first matching term from the precedence list:
$overallStatus = $statusIndex.Where({$_ -in $statusValueSet}, 'First')
Value of $overallStatus should now be 'log' as expected.
3-4 lines of code instead of 9-10 :)
Screenshot 2The one screen shot of this errorissue I am building an app using api.ai , an syllabus app which tells you the syllabus, but when I invoke it with desired parameters like branch and semester I have made each individual intent for it even then I'm getting miss answers sometimes like when asked for sem 4 and branch electronics its showing sem 3 sem 4 or of other branch . I have given sem and branch as required n given few invoking statements even then getting this. Tried even training it manually for free 30s of actions on api.ai no solution please help. Not using any web hook , context , event.
Short answer - check here for screenshots http://imgur.com/a/tVBlD
Long answer - You have two options
1) Create 3 separate custom entities for each branch type (computer science, civil, communication) which you need to attach to your branch parameter
2) Using the sys.any entity and attaching it to your branch parameter; then determining what the incoming parameter value is on a server then sending back a response through a webhook.
If you go the second route, you have to create a webhook and hardcode recognized words like 'computer science' in IF statements which check the incoming parameter (sent through JSON from API.AI). This route will be more difficult but I think you will have to travel it regardless because you will have backend architecture which you access to find and return the syllabus.
Note the second route is what I did to solve a similar issue.
You can also use regex to match an item in a list which limits the amount of hardcoding and if statements you have to do.
Python regex search example
baseurl = "http://mywebsite.com:9001/"
# Parse the document
# Build the URL + File Path and Parse the Document
url = baseurl + 'Data'
xmlLink = urllib.request.urlopen(url)
xmlData = etree.parse(xmlLink)
xmlLink.close()
# Find the number of elements to cycle through
numberOfElements = xmlData.xpath("count(//myData/data)")
numberOfElements = int(numberOfElements)
types = xmlData.xpath("//myData/data")
# Search the string
i = 0
while numberOfElements > i:
listSearch= types[i].text
match = re.search(parameter, listSearch, re.IGNORECASE)
if match is None:
i += 1
else:
# Grab the ID
elementID = types[i].get('id')
i = 0
break
An simple trick would be what i did, just have an entity saved for both branch and semester , use sys.original parameters and an common phrase for provoking each intent saves up the hard work.
In one of my scripts I use the Getopt::Long library. At the beginning of the program I make a call:
&GetOptions ('help', 'debug', 'user=s' => \$GetUser);
The first two arguments are simple: I discover their existance by checking $opt_help and $opt_debug respectively. However the third argument is tricky, because I need to distinguish between no option at all ($GetUser is undefined, which is ok for me), using "--user" alone ($GetUser is also undefined, but this time I want to display an error message) and "--user FooBar" (where the $GetUser receives 'FooBar', which I can use in further processing).
How can I distinguish between using no "--user" option and using it alone, without a username?
You are looking for : instead of =, so 'user:s' => \$GetUser. From Options with values
Using a colon : instead of the equals sign indicates that the option value is optional. In this case, if no suitable value is supplied, string valued options get an empty string '' assigned, while numeric options are set to 0
This allows you to legitimately call the program with --user and no value (with = it's an error). Then you only declare my $GetUser; and after the options are processed you can tell what happened. If it is undef it wasn't mentioned, if it is '' (empty string) it was invoked without a value and you can emit your message. This assumes that it being '' isn't of any other use in your program.
Otherwise, when you use 'user=s' and no value is given, the GetOptions reports an error by returning false and emits a descriptive message to STDERR. So you may well leave it and do
GetOptions( 'user=s' => ...) or die "Option error\n";
and rely on the module to catch and report wrong use. Our own message above isn't really needed as module's messages clearly describe the problem.
One other way of doing this would go along the lines of
usage(), exit if not GetOptions('user=s' => \$GetUser, ...);
sub usage {
# Your usage message, briefly listing options etc.
}
I'd like to add – you don't need & in front of a function call. It makes the caller's #_ visible, ignores function prototype, and does a few other similarly involved things. One common use is to get a coderef, $rc = \&fun, where it is needed. See for example this post
I am new to using intersytems cache and face an issue where I am querying data stored in cache, exposed by classes which do not seem to accurately represent the data in the underlying system. The data stored in the globals is almost always larger than what is defined in the object code.
As such I get errors like the one below very frequently.
Msg 7347, Level 16, State 1, Line 2
OLE DB provider 'MSDASQL' for linked server 'cache' returned data that does not match expected data length for column '[cache]..[namespace].[tablename].columname'. The (maximum) expected data length is 5, while the returned data length is 6.
Does anyone have any experience with implementing some type of quality process to ensure that the object definitions (sql mappings) are maintained in such away that they can accomodate the data which is being persisted in the globals?
Property columname As %String(MAXLEN = 5, TRUNCATE = 1) [ Required, SqlColumnNumber = 2, SqlFieldName = columname ];
In this particular example the system has the column defined with a max len of 5, however the data stored in the system is 6 characters long.
How can I proactively monitor and repair such situations.
/*
I did not create these object definitions in cache
*/
It's not completely clear what "monitor and repair" would mean for you, but:
How much control do you have over the database side? Cache runs code for a data-type on converting from a global to ODBC using the LogicalToODBC method of the data-type class. If you change the property types from %String to your own class, AppropriatelyNamedString, then you can override that method to automatically truncate. If that's what you want to do. It is possible to change all the %String property types programatically using the %Library.CompiledClass class.
It is also possible to run code within Cache to find records with properties that are above the (somewhat theoretical) maximum length. This obviously would require full table scans. It is even possible to expose that code as a stored procedure.
Again, I don't know what exactly you are trying to do, but those are some options. They probably do require getting deeper into the Cache side than you would prefer.
As far as preventing the bad data in the first place, there is no general answer. Cache allows programmers to directly write to the globals, bypassing any object or table definitions. If that is happening, the code doing so must be fixed directly.
Edit: Here is code that might work in detecting bad data. It might not work if you are doing cetain funny stuff, but it worked for me. It's kind of ugly because I didn't want to break it up into methods or tags. This is meant to run from a command prompt, so it would have to be modified for your purposes probably.
{
S ClassQuery=##CLASS(%ResultSet).%New("%Dictionary.ClassDefinition:SubclassOf")
I 'ClassQuery.Execute("%Library.Persistent") b q
While ClassQuery.Next(.sc) {
If $$$ISERR(sc) b Quit
S ClassName=ClassQuery.Data("Name")
I $E(ClassName)="%" continue
S OneClassQuery=##CLASS(%ResultSet).%New(ClassName_":Extent")
I '$IsObject(OneClassQuery) continue //may not exist
try {
I 'OneClassQuery.Execute() D OneClassQuery.Close() continue
}
catch
{
D OneClassQuery.Close()
continue
}
S PropertyQuery=##CLASS(%ResultSet).%New("%Dictionary.PropertyDefinition:Summary")
K Properties
s sc=PropertyQuery.Execute(ClassName) I 'sc D PropertyQuery.Close() continue
While PropertyQuery.Next()
{
s PropertyName=$G(PropertyQuery.Data("Name"))
S PropertyDefinition=""
S PropertyDefinition=##CLASS(%Dictionary.PropertyDefinition).%OpenId(ClassName_"||"_PropertyName)
I '$IsObject(PropertyDefinition) continue
I PropertyDefinition.Private continue
I PropertyDefinition.SqlFieldName=""
{
S Properties(PropertyName)=PropertyName
}
else
{
I PropertyName'="" S Properties(PropertyDefinition.SqlFieldName)=PropertyName
}
}
D PropertyQuery.Close()
I '$D(Properties) continue
While OneClassQuery.Next(.sc2) {
B:'sc2
S ID=OneClassQuery.Data("ID")
Set OneRowQuery=##class(%ResultSet).%New("%DynamicQuery:SQL")
S sc=OneRowQuery.Prepare("Select * FROM "_ClassName_" WHERE ID=?") continue:'sc
S sc=OneRowQuery.Execute(ID) continue:'sc
I 'OneRowQuery.Next() D OneRowQuery.Close() continue
S PropertyName=""
F S PropertyName=$O(Properties(PropertyName)) Q:PropertyName="" d
. S PropertyValue=$G(OneRowQuery.Data(PropertyName))
. I PropertyValue'="" D
.. S PropertyIsValid=$ZOBJClassMETHOD(ClassName,Properties(PropertyName)_"IsValid",PropertyValue)
.. I 'PropertyIsValid W !,ClassName,":",ID,":",PropertyName," has invalid value of "_PropertyValue
.. //I PropertyIsValid W !,ClassName,":",ID,":",PropertyName," has VALID value of "_PropertyValue
D OneRowQuery.Close()
}
D OneClassQuery.Close()
}
D ClassQuery.Close()
}
The simplest solution is to increase the MAXLEN parameter to 6 or larger. Caché only enforces MAXLEN and TRUNCATE when saving. Within other Caché code this is usually fine, but unfortunately ODBC clients tend to expect this to be enforced more strictly. The other option is to write your SQL like SELECT LEFT(columnname, 5)...
The simplest solution which I use for all Integration Services Packages, for example is to create a query that casts all nvarchar or char data to the correct length. In this way, my data never fails for truncation.
Optional:
First run a query like: SELECT Max(datalength(mycolumnName)) from cachenamespace.tablename.mycolumnName
Your new query : SELECT cast(mycolumnname as varchar(6) ) as mycolumnname,
convert(varchar(8000), memo_field) AS memo_field
from cachenamespace.tablename.mycolumnName
Your pain of getting the data will be lessened but not eliminated.
If you use any type of oledb provider, or if you use an OPENQUERY in SQL Server,
the casts must occur in the query sent to Intersystems CACHE db, not in the the outer query that retrieves data from the inner OPENQUERY.
When I preform an LDAP search like so
my $mesg = $ldap->search(
base => "$dn",
scope => 'base',
filter => '(objectClass=*)',
attrs => ['member'],
);
Should my script just log if $mesg->{resultCode} is not zero, or should by script log and die on not zero?
This is entirely up to the intended flow of your program - there isn't a general "should" or "should not".
If the code that follows depends on the search and is meaningless without it, you may die, otherwise you may skip the error and try to recover somehow.
One of the Unix principles, however, suggests that generally a program should fail as early as possible:
Rule of Repair: When you must fail, fail noisily and as soon as possible.
Note that there are result codes from LDAP search requests that are non-zero, yet do not indicate failure. Time limit exceeded and size limit exceeded are two examples where search results are returned, yet the result code is non-zero.