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why? whatsapp is a vangav backend template covering: service oriented architecture, worker service, multi-entry-point api, basic authentication and multi-keysapce database

whatsapp

• whatsapp, whatsapp worker and whatsapp analytics services work together and are generated using vangav backend

prerequisite

• vangav backend tutorials

functionality

whatsapp

• handles user signup and authentication
• sending messages
• fetching messages and users' info
• dispatching analytics writing to whatsapp worker

whatsapp worker

• handles writing analytics into the database

whatsapp analytics

• handles fetching users' and messages' analytics

overview

• this service is based on vangav backend's whatsapp template
• this service has the 90+% of the vangav backend's generated code + the 10-% of the logic code needed to complete the service

try this service

1. for first timers - follow the steps in the system requirements tutorial
2. for first timers - follow the steps in the workspace initialization tutorial
3. download vos_whatsapp.zip, vos_whatsapp_worker.zip and vos_whatsapp_analytics.zip projects (from the green clone or download button) inside the workspace directory created previously (my_services) and unzip them
4. rename unzipped directories, remove the -master from their names
5. in the terminal cd to vos_whatsapp/cassandra/cql/
6. execute ./_start_cassandra.sh to start cassandra
7. cd to vos_whatsapp/cassandra/cql/drop_and_create/
8. execute the commands ./_execute_cql.sh wa_....cql to initialize the services' database tables; repeat this step for all the .cql files
9. cd to vos_whatsapp_worker and execute ./_run.sh to start the whatsapp worker service on port 8000
10. cd to vos_whatsapp_analytics and execute ./_run.sh 7000 to start the whatsapp analytics service on port 7000
11. cd to vos_whatsapp and execute ./_run.sh to start the whatsapp service on port 9000
12. from your prefered client (we recommned postman) start trying the service; refer to the features and service references sections for reference

• at the end to stop the services: press control + d in the terminal session where each service was started in (9, 10 and 11)
• to stop cassandra: execute ps auwx | grep cassandra to get cassandra's (pid) then kill -9 (pid) to stop cassandra

eclipse

• follow the following steps to import the downloaded backend service in eclipse

1. cd to the service's directory and execute the ./_eclipsify.sh script
2. file > import > general > existing projects into workspace > next > set "select root directory" to my_services > under projects make sure that vos_calculate_sum is selected > finish
3. double check the java version used for compiling the project: right click the project > properties > java compiler > enable project specific settings > compiler compliance level > 1.7 or 1.8

covered topics

• generate multiple services (main + worker + analytics) to work together in a service oriented architecture
• generate a multi-keyspace database
• basic authentication

features

whatsapp

controller(s)	feature
signup	handles new users' signup using phone numbers
send message	handles sending a message
get messages and get user info	handles getting new messages and users' info (id, name, ...)

whatsapp analytics

controllers	feature
get users count and get messages count	handles fetching analytics data (total counts and count per-day)

service references

whatsapp

reference	explanation
routes	api routes
controllers.json	api request/response's elements
wa_auth.keyspace	wa_auth is the keyspace used for all authentication-related tables
wa_users.keyspace	wa_users is the keyspace used for all users-info-related tables
wa_chat.keyspace	wa_chat is the keyspace used for all chat-related tables
wa_blobs.keyspace	wa_blobs is the keyspace used for all blobs-related tables
wa_analysis.keyspace	wa_analysis is the keyspace used for all analysis-related tables
common	handles controllers' common operations like authentication
controllers	api implementation
wa_auth	wa_auth cassandra's keyspace client
wa_users	wa_users cassandra's keyspace client
wa_chat	wa_chat cassandra's keyspace client
wa_blobs	wa_blobs cassandra's keyspace client
wa_analysis	wa_analysis cassandra's keyspace client

whatsapp analytics

reference	explanation
routes	api routes
controllers.json	api request/response's elements
wa_analysis.keyspace	wa_analysis is the keyspace used for all analysis-related tables
controllers	api implementation
wa_analysis	wa_analysis cassandra's keyspace client

change log

• this section lists the 10-% code added after vangav backend generated 90+% of the code

whatsapp

file/dir	change
common	added common controllers' operations like authentication
controllers	added the implementation of request processing logic under controller_name/HandlerControllerName.java classes and nested response json structures under controller_name/response_json packages

whatsapp analytics

file/dir	change
controllers	added the implementation of request processing logic under controller_name/HandlerControllerName.java classes and nested response json structures under controller_name/response_json packages

error codes

• following are the error codes of whatsapp services

whatsapp

class	code : sub_code	explanation
CommonPlayHandler
	300 : 1	user not signed up
	300 : 2	wrong password
HandlerSignup
	301 : 1	user has no password
	301 : 2	wrong password
HandlerGetUserInfo
	302 : 1	user not registered
	302 : 2	didn't find user's info
HandlerSendMessage
	303 : 1	can't send message(s) to yourself
	303 : 2	message's recieving user isn't registered
HandlerGetMessages
	304 : 1	didn't find message's blob (content)

whatsapp analytics

class	code : sub_code	explanation
HandlerGetMessagesCount
	400 : 1	to-date is smaller than from-date
HandlerGetUsersCount
	401 : 1	to-date is smaller than from-date

notes

• whatsapp, whatsapp worker and whatsapp analytics services has no connection with WhatsApp Inc.; these services are just a vangav backend template to demonstrate using some features/utilities in the context of texting apps
• the "whatsapp" name is used for users to easier understand the services' design, features and source code

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