Hiring guide for ECL (Enterprise Control Language) Engineers

ECL (Enterprise Control Language) Developer Hiring Guide

ECL (Enterprise Control Language) is a declarative, data-centric programming language developed by LexisNexis Risk Solutions. Introduced in the early 2000s, ECL was created to manage and analyze large volumes of data for enterprise-level applications. The language operates on HPCC Systems platform, an open-source big-data computing system designed by the same company. Its high-level syntax simplifies complex data manipulations and transformations while ensuring efficient execution across massive datasets. Information about ECL's history and functionality can be found on official HPCC Systems' website as well as various academic research publications.

Ask the right questions secure the right ECL (Enterprise Control Language) talent among an increasingly shrinking pool of talent.

First 20 minutes

General ECL (Enterprise Control Language) app knowledge and experience

The first 20 minutes of the interview should seek to understand the candidate's general background in ECL (Enterprise Control Language) application development, including their experience with various programming languages, databases, and their approach to designing scalable and maintainable systems.

What are the basic components of ECL?
The basic components of ECL include Datasets, Transform Functions, Actions, and Attributes.
How would you define a dataset in ECL?
In ECL, a dataset is defined by providing a layout that describes the data, and a method to extract the data. The layout is a record definition and the method could be a file service function.
What is the purpose of the OUTPUT action in ECL?
The OUTPUT action in ECL is used to write the results of an ECL query to a file or to the workunit.
Describe the difference between a SET and a DATASET in ECL.
A SET in ECL is a collection of like-typed data items, while a DATASET is a collection of records. Each record in a DATASET can have multiple fields of different types.
How would you use the JOIN function in ECL?
The JOIN function in ECL is used to combine two datasets based on a common key. The syntax involves specifying the two datasets, the join condition, and the transform function to apply to matching records.
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What you’re looking for early on

Does the candidate have a solid understanding of ECL?
Has the candidate demonstrated problem-solving skills?
Is the candidate familiar with data manipulation and data management techniques?
Has the candidate shown the ability to work as part of a team?

Next 20 minutes

Specific ECL (Enterprise Control Language) development questions

The next 20 minutes of the interview should focus on the candidate's expertise with specific backend frameworks, their understanding of RESTful APIs, and their experience in handling data storage and retrieval efficiently.

What are the different types of JOINs in ECL?
ECL supports several types of JOINs including INNER, LEFT OUTER, RIGHT OUTER, FULL OUTER, and CROSS.
Describe the difference between a SORTED and a GROUPED dataset in ECL.
A SORTED dataset in ECL is one where the records are arranged in a specific order based on one or more fields. A GROUPED dataset is similar, but the records are also divided into groups based on a grouping condition.
How would you handle missing data in ECL?
Missing data in ECL can be handled using the DEFAULT function, which provides a default value when a field is missing or NULL.
What is the purpose of the DEDUP function in ECL?
The DEDUP function in ECL is used to remove duplicate records from a dataset. It can be used with different options to control which records are considered duplicates and which record is kept.
Describe the difference between a PROJECT and a TABLE function in ECL.
The PROJECT function in ECL is used to create a new dataset by applying a transform function to each record in an existing dataset. The TABLE function is similar, but it also allows you to specify a grouping condition to create a grouped dataset.
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The ideal back-end app developer

What you’re looking to see on the ECL (Enterprise Control Language) engineer at this point.

At this point, a skilled ECL (Enterprise Control Language) engineer should demonstrate strong problem-solving abilities, proficiency in ECL (Enterprise Control Language) programming language, and knowledge of software development methodologies. Red flags include lack of hands-on experience, inability to articulate complex concepts, or unfamiliarity with standard coding practices.

Digging deeper

Code questions

These will help you see the candidate's real-world development capabilities with ECL (Enterprise Control Language).

What does this simple ECL code do?
IMPORT STD; STD.System.Thorlib.echo('Hello, World!');
This code imports the standard library and then uses the echo function from the Thorlib module to print 'Hello, World!' to the console.
What will be the output of this ECL code snippet?
SET OF STRING10 Cities := ['New York', 'London', 'Paris']; OUTPUT(Cities);
This code defines a set of strings named 'Cities' and assigns three city names to it. The OUTPUT function then prints these city names.
What does this ECL code do that involves array manipulation?
SET OF INTEGER MyNumbers := [1, 2, 3, 4, 5]; MyNumbers := MyNumbers[2..4]; OUTPUT(MyNumbers);
This code first defines a set of integers named 'MyNumbers' and assigns five numbers to it. Then it reassigns 'MyNumbers' to be a subset of itself, specifically the second through fourth elements. The OUTPUT function then prints these three numbers.
What does this ECL code do that involves threading?
IMPORT STD; STD.Parallel.ParallelSleep(1, 5);
This code imports the standard library and then uses the ParallelSleep function from the Parallel module to pause execution of the current thread for five seconds.

Wrap-up questions

Final candidate for ECL (Enterprise Control Language) Developer role questions

The final few questions should evaluate the candidate's teamwork, communication, and problem-solving skills. Additionally, assess their knowledge of microservices architecture, serverless computing, and how they handle ECL (Enterprise Control Language) application deployments. Inquire about their experience in handling system failures and their approach to debugging and troubleshooting.

How would you optimize an ECL query for performance?
ECL query performance can be optimized by minimizing data movement, using indexes, optimizing joins, and using the CHOOSEN function to limit the number of records processed.
What are the different types of indexes in ECL and how are they used?
ECL supports two types of indexes: keyed and non-keyed. Keyed indexes are used for fast access to data based on a key, while non-keyed indexes are used for full-text search.
Describe the difference between a MODULE and a SERVICE in ECL.
A MODULE in ECL is a collection of related ECL definitions, while a SERVICE is a MODULE that is designed to be used by other ECL code. A SERVICE can include actions, which are functions that can be called remotely.

ECL (Enterprise Control Language) application related

Product Perfect's ECL (Enterprise Control Language) development capabilities

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