eCommerce Aggregator
====================

Introduction
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Users experience a difficulty switching between tabs, manually visiting
different website to check different products and prices. Our team
helped one of our client to solve aggregation issue in eCommerce domain.
Focus of the project was to:

#. Allowing users to search based on natural queries
#. Aggregate products from 100+ sites onto one platform
#. Providing analytics & monetization tools

Key challenges
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#. Dealing with un-structured data, no single source of API
#. Monitoring Prices & Out of Stock Status near real-time
#. Building a machine learned automatic classification model 

Architecture
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.. image:: images/skoov_prod_setup.png

Data Collection
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A typical eCommerce Aggregator has to collect data relating to:

#. Products across diverse categories
#. Deals & Special promotions from various partner sites
#. Banners for AdServer

eCommerce sites are built using frameworks/SAAS services like Magento, Shopify
or WooCommerce.At times syncing product catalog with aggregator become tricky 
because API access may not be readily available. The only option in this case 
is to crawl individual sites, in do so one is faced with following challenges:

#. Variations in HTML of different websites
#. Difficulty in scraping because of client side MVC framework {E.g. React.js}
#. Frequent changing in layout by partner sites
#. Rate limiting filter on partner sites

For handling this scenario, we had developed custom crawler with following 
features:

#. Unified infrastructure to crawl from both APIs and Website
#. Ability to crawl Deals and New Arrivals on daily basis
#. Ability to scale crawling using distributed setup
#. Custom Proxy Farm to solve rate-limiting issue
#. Test suite to report breakage of parsers
#. Auto Categorize products based on heuristics at crawl time

We had come-up with this solution after evaluating of existing opensource
crawlers like Nutch. With our current setup we were able to process crawl
cycle of about 3,000,000 pages in about 4 days over cluster of 5 nodes

Price & Out of Stock Monitoring
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Upto-date prices are key while aggregating products from multiple sites.
This is one of the key reasons why we had to put special engineering effort
into making sure prices are updated regularly. Another sub-problem that
needed to be solved while addressing price updates was to make sure
products that were ranked higher on search engine were available in stock. 
Basically we need to keep track of product availability on source site.

.. image:: images/skoov_oos_setup.png

These issues were solved by:

#. Identification of categories with high volatile prices. Our research found
   Electronics and Fashion Categories {Specially Women Fashion} were volatile
#. Periodic prices updates both Volatile and Non-Volatile categories
#. Real-time price checks: When a user clicks on product details we use to
   perform price check in real time

All these steps allowed us to give better user experience and keep out catalog
fresh

Custom Search Engine Features
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Search is an important differentiator for most online businesses. In computer science
it is an active area of research. To make improvements on search engine
key focus areas include:

#. Understanding users intent
#. Making search engine resilient to typos
#. Creating a ranking model that aligns Business and Users preferences
#. Giving structured response to ambiguous queries

Lets say a user types in 

#. blue checked shirt
#. blue checked shirts for men
#. blue checked shirts for women less than 2000

The intent in these three cases is different, a traditional keyword based
search would have treated all the three results almost the same.
Our custom implementation of search engine handled this issue by identifying
following attributed in a query

#. Product Category
#. Color
#. Special Attributes {E.g. 4g compatible mobiles, 24gb storage phones}
#. Gender
#. Price Quantification {including ranges E.g. between 300 and 500}
#. Brand

Users will not always type in the right query, including the correct spelling
the onus of figuring out what the user meant is huge, let look at some of
cases that a typical search engines have to handle:

#. Typos: {E.g. bleu shirt when they actually meant blue shirt}
#. Synonyms {E.g. black blazer and black suit}
#. Specific model {E.g. Moto X Play}
#. Query Segment at wrong place {E.g. samsung suit case as opposed to samsung suitcase}
#. Dealing with abbreviated units {E.g. GB, Gigabytes}

These issues are generally taken care of with special run-time string transformations
that make a query more consistent to indexing scheme. 

Ranking is a core component that needs to get right, it needs to be balanced in a sense
Business Objective and User Experience Objectives are met. Lets say as
part of key partnership Business might want to promote a brand even when the user is looking
to purchase competing brand. How do you rank products in that case?

Machine Learned models are frequently use technique, however they do have few limitations
that we faced while experimenting during project

#. Frequent re-training: When adding a new product category, we may need to update
   model for our ranking algorithm
#. Difficulty in bootstrap: Labeled dataset is often needed and we may need to 
   keep updating when you're starting off this might be difficult to come-by
#. High runtime computation requirement: This is specially true if you're using
   ensembled models

After we experimented with different methods, we came up with a simple
linear score based method which solved our requirements. These factors included

#. Site specific boosting factor
#. Brand specific boosting factor
#. Freshness

Based on these scheme we achieved our objective of flexibility and control while
implementing our custom ranking model.

Recommendation Engine
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Related products & query is a feature that allows cross selling of
products and services. To improve engagement effort is put into these features

During this projects following are zones on which we have implemented
recommendations

#. Deals & Offers
#. Products Detail Page
#. Search Engine Results Page {related Categories}

Since often in eCommerce users browser without logging in we had to use 
Content Based Recommendation, this allowed to find related products when
a user looks at a product. Few customization in our Engine behaviour were done
for Fashion we wanted to show more diverse results {E.g. When shopping trousers
we also wanted to show Belts, Shoes etc}. For electronics categories we avoided
this diversification.

Analytics & Monetization
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Metrics for every product needed to be collected:

#. Basic Web Analytics {E.g. Visits, Pages/Session etc}
#. Engagement Metrics {E.g Searches/Sessions, Clicks/Session}

Few Business metrics were also needed for Affiliate Management. 
E.g. any time a user was referred to a partner site we had to maintain log. 
This was done for compliance with Revenue Sharing Agreement and any Business
Contracts we might have with the partner site.

Operational metrics were also collected for checking Server Operations,
Crawl related metrics. Number of products going out of stock.

An Adserver was also configured to run Banner campaings earning revenue for project.

Software Components Used
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#. **Django**: Pythonic Web Framework for building Web Applications
#. **Django REST Framework**: Building APIs that other applications can use to talk to Registry
#. **Postgres**: Database for storing and retrieving information
#. **Apache Solr**: Search engine component to allow users search by different parameters
#. **Bootstrap + jQuery**: For implementing frontend validations
#. **Celery**: Background tasks and periodic tasks
#. **Scikit Learn**: For building classification and ranking model
#. **Revive**: Adserver that was used to run Banner campaigns on behalf of partner sites
#. **Nagios**: Server monitoring and alerting system

Project Management
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#. Entire technology aspect was taken care by our team
#. Our team followed Agile approach for implementing the project
#. Our tech team participated in weekly standups
#. Daily summary reports along with push to staging instances were done
#. Onboarding of partners by doing technical consulting was also done by
   our team