I'm just getting started with Apache NiFi and I'm curious if there are any best practices around using a attributes vs content for a FlowFile. Currently, I have it setup to read a JSON message from a RabbitMQ queue, parse the JSON into attributes and use those attributes for downstream processing. This works, but I feel like its leaving the content of the FlowFile largely unused after JSON parsing and I'm wondering if I'm missing something. Alot of the processors seem more geared towards working with attributes but are there any disadvantages to primarily using attributes for processing?
In my use case, the RabbitMQ message would be an event that a new document has been made available and the flow I'm building would have branching logic based on the document type to extract data from the document via NLP processes. Currently, I'm storing the document text as and attribute but I'm wondering if there are any size considerations to account for with attributes. Some documents could be hundreds of pages and therefore lots of text.
Thanks!
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This is a very broad question, I’m new to Flink and looking into the possibility of using it as a replacement for a current analytics engine.
The scenario is, data collected from various equipment, the data is received As a JSON encoded string with the format of {“location.attribute”:value, “TimeStamp”:value}
For example a unitary traceability code is received for a location, after which various process parameters are received in a real-time stream. The analysis is to be ran over the process parameters however the output needs to include a relation to a traceability code. For example {“location.alarm”:value, “location.traceability”:value, “TimeStamp”:value}
What method does Flink use for caching values, in this case the current traceability code whilst running analysis over other parameters received at a later time?
I’m mainly just looking for the area to research as so far I’ve been unable to find any examples of this kind of scenario. Perhaps it’s not the kind of process that Flink can handle
A natural way to do this sort of thing with Flink would be to key the stream by the location, and then use keyed state in a ProcessFunction (or RichFlatMapFunction) to store the partial results until ready to emit the output.
With a keyed stream, you are guaranteed that every event with the same key will be processed by the same instance. You can then use keyed state, which is effectively a sharded key/value store, to store per-key information.
The Apache Flink training includes some explanatory material on keyed streams and working with keyed state, as well as an exercise or two that explore how to use these mechanisms to do roughly what you need.
Alternatively, you could do this with the Table or SQL API, and implement this as a join of the stream with itself.
I'm trying to integrate nifi REST API's with my application. So by mapping input and output from my application, I am trying to call nifi REST api for flow creation. So, in my use case most of the times I will extract the JSON values and will apply expression languages.
So, for simplifying all the use-cases I am using evaluate JSONpath processor for fetching all attributes using jsonpath and apply expression language function on that in extract processor. Below is the flow diagram regarding that.
Is it the right approach because for JSON to JSON manipulation having 30 keys this is the simplest way, and as I am trying to integrate nifi REST API's with my application I cannot generate JOLT transformation logic dynamically based on the user mapping.
So, in this case, does the usage of evaluating JSONpath processor creates any performance issues for about 50 use case with different transformation logic because as I saw in documentation attribute usage creates performance(regarding memory) issues.
Your concern about having too many attributes in memory should not be an issue here; having 30 attributes per flowfile is higher than usual, but if these are all strings between 0 - ~100-200 characters, there should be minimal impact. If you start trying to extract KB worth of data from the flowfile content to the attributes on each flowfile, you will see increased heap usage, but the framework should still be able to handle this until you reach very high throughput (1000's of flowfiles per second on commodity hardware like a modern laptop).
You may want to investigate ReplaceTextWithMapping, as that processor can load from a definition file and handle many replace operations using a single processor.
It is usually a flow design "smell" to have multiple copies of the same flow process with different configuration values (with the occasional exception of database interaction). Rather, see if there is a way you can genericize the process and populate the relevant values for each flowfile using variable population (from the incoming flowfile attributes, the variable registry, environment variables, etc.).
For every processor there is a way to configure the processor and there is a context menu to view data provenance.
Is there a good explanation of what is data provenance?
Data provenance is all about understanding the origin and attribution of data. In a typical system you get 'logs'. When you consider data flowing through a series of processes and queues you end up with a lot of lots of course. If you want to follow the path a given piece of data took, or how long it took to take that path, or what happened to an object that got split up into different objects and so on all of that is really time consuming and tough. The provenance that NiFi supports is like logging on steroids and is all about keeping and tracking these relationships between data and the events that shaped and impacted what happened to it. NiFi is keeping track of where each piece of data comes from, what it learned about the data, maintains the trail across splits, joins, transformations, where it sends it, and ultimately when it drops the data. Think of it like a chain of custody for data.
This is really valuable for a few reasons. First, understanding and debugging. Having this provenance capture means from a given event you can go forwards or backwards in the flow to see where data came from and went. Given that NiFi also has an immutable versioned content store under the covers you can also use this to click directly to the content at each stage of the flow. You can also replay the content and context of a given event against the latest flow. This in turn means much faster iteration to the configuration and results you want. This provenance model is also valuable for compliance reasons. You can prove whether you sent data to the correct systems or not. If you learn that you didn't then have data with which you can address the issue or create a powerful audit trail for follow-up.
The provenance model in Apache NiFi is really powerful and it is being extended to the Apache MiNiFi which is a subproject of Apache NiFi as well. More systems producing more provenance will mean you have a far stronger ability to track data from end-to-end. Of course this becomes even more powerful when it can be combined with other lineage systems or centralized lineage stores. Apache Atlas may be a great system to integrate with for this to bring a centralized view. NiFi is able to not only do what I described above but to also send these events to such a central store. So, exciting times ahead for this.
Hope that helps.
Using Talend ESB 5.2.0, I want to create a mediation route that will call a processing job on the payload of an inbound request to a CXF messaging endpoint, however my current implementation is suffering some performance issues with large payloads.
I’ve investigated the issue and found that the bottleneck is in marshalling my inbound XML payload from the tRouteInput component to the internal row structure for processing, using a tXMLMap.
Is it possible, using a built-in type converter in the route, to marshal the internal row structure from the route and stream through POJOs or transport objects that are cheaper to process in the job? Or is there a better way to marshal XML to Talend’s internal row structure from a route using a less expensive transform?
Any thoughts would be welcome.
Cheers,
mids
It turns out that the issue was caused by the format of the inbound XML payload - having more than one loop element mapping to separate output flows from the tXMLMap generates relative links for each item for each output flow, enabling more advanced processing involving the loops if required.
This caused the large memory overhead that led to poor throughput.
Not requiring any more advanced processing in the XML to Talend row conversion, we overcame this issue by splitting the payload to its distinct loop elements using tReplicate and tExtractXMLField components before mapping out of the XML in separate tXMLMaps to avoid the auto-generation of those links.- mids
The question environment relates to JavaEE, Spring
I am developing a system which can start and stop arbitrary TCP (or other) listeners for incoming messages. There could be a need to authenticate these messages. These messages need to be parsed and stored in some other entities. These entities model which fields they store.
So for example if I have property1 that can have two text fields FillLevel1 and FillLevel2, I could receive messages on TCP which have both fill levels specified in text as F1=100;F2=90
Later I could add another filed say FillLevel3 when I start receiving messages F1=xx;F2=xx;F3=xx. But this is a conscious decision on the part of system modeler.
My question is what do you think is better to use for parsing and storing the message. ETL (using Pantaho, which is used in other system) where you store the raw message and use task executor to consume them one by one and store the transformed messages as per your rules.
One could use Espr or Drools to do the same thing , storing rules and executing them with timer, but I am not sure how dynamic you could get with making rules (they have to be made by end user in a running system and preferably in most user friendly way, ie no scripts or code, only GUI)
The end user should be capable of changing the parse rules. It is also possible that end user might want to change the archived data as well (for example in the above example if a new value of FillLevel is added, one would like to put a FillLevel=-99 in the previous values to make the data consistent).
Please ask for explanations, I have the feeling that I need to revise this question a bit.
Thanks
Well Esper is a great CEP engine, but drools has it's own implementation Drools Fusion which integrates really well with jBpm. That would be a good choice.