Blog Workflow

blog.yml

name: blog-tutorial
description: |
  A blog workflow
  
  Go to blog page at {$configs.domain} to publish some articles!
  
services:
  # httpServer service serves any content over HTTP.
  httpServer: https://github.com/ilgooz/service-http-server
  
  # website service serves a VueJS app that has features for
  # articles' creation and listing.
  # VueJS app makes API calls to RESTful/GraphQL API to manage articles.
  website: ...
  
  # articles service manages articles and stores them in MongoDB.
  articles: https://github.com/ilgooz/service-articles
  
  # mailer service sends emails to receivers with provided content.
  mailer: https://github.com/mesg-foundation/service-email-sendgrid
  
  # location service provides location from ip address.
  location: https://github.com/ilgooz/service-location
  
  # stats service stores stats in a time series database, InfluxDB.
  # You can watch the stats with Grafana web UI at http://localhost:3000.
  stats: https://github.com/mesg-foundation/service-influxdb
  
configs:
  # Domain name for accessing to website and APIs.
  domain: http://localhost:2300
  
  # SendGrid API key that will be used by mailer service while sending emails.
  sendgridAPIKey: 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
  
  # noreply mail address of MESG.
  noRepy: noreply@mesg.com
  
  # When a new article is created, an email will be sent to each user on this list.
  defaultUsers:
    - name: Hey MESG
      email: hey@mesg.com
 
# start point of the workflow.
when:

  httpserver:
    event:
      request:
        execute:
        
          # getPage gets requested page from website application.
          getPage:
            website: serve
            filter:
              path:
                match: ^(?!(\/api)).*
            # we can also introduce ! syntax for ignoring setting empty values.
            # in that case if a field has ! at the beginning and it's value ends up
            # being empty, in that case it'll not be set at all.
            # e.g.: !path
            map:
              path: {$event.data.path}
              host: {$event.data.host}
              method: {$event.data.method}
          
          # servePage serves given page via httpserver.
          servePage:
            httpserver: completeSession
            dependsOn:
              getPage: success
            map:
              sessionID: {$event.data.sessionID}
              content: {$getPage.data.content}
              mimeType: {$getPage.data.mimeType}
          
          # locateUser finds user's location from ip address.
          locateUser:
            location: locate
            map:
              ip: {$event.data.userIP}
              
          # creates an article if request is made for it.
          createArticle:
            articles: save
            dependsOn:
              locateUser: location
            filter:
              path:
                match: \/api\/.*
              method: post
            map:
              article:
                title: {$event.data.article.title}
                content: {$event.data.article.content}
                location:
                  country: {$locateUser.data.country}
                  city: {$locateUser.data.city}
          
          # serveArticleCreation serves article via httpserver.
          serveArticleCreation:
            httpServer: completeSession
            dependsOn:
              createArticle: success
            map:
              sessionID: {$event.data.sessionID}
              content:
                article: {$createArticle.data.article}
              mimeType: application/json
          
          # informUsers execution sends emails to users to notify them about the new article.
          informUsers:
            mailer: send
            dependsOn:
              createArticle: success
            map:
              subject: A New Article Published — {$createArticle.data.title}
              text: |
                You can access to article from the link: 
                <a href="{$configs.domain}/{$saveArticle.data.id}">{$createArticle.data.title}</a>
              from: {$config.noReply}
              to: {@map($config.users, (user) => {return user.email})}
              apiKey: {$configs.sendgridAPIKey}
          
          logInformUsers:
            bluelogger: log
            dependsOn:
              informUsers: success
              createArticle: success
            map:
              message: users notified for the new '{$createArticle.data.title}' article
              data:
                receivers: {$config.users}
            
          # recordVisit records every visit to httpServer via stats service.
          # It uses location info and the name of the endpoint that being requested
          # as meta data.
          # You can navigate to Grafana to see this data points in a chart with
          # the visualised meta data.
          recordVisit:
            stats: write
            dependsOn:
              locateUser: location
              !saveArticleCreation: success # ! indicates optional.
              !website: success
            map:
              measurement: {@if(
                @match(\/api\/.*, $event.data.path),
                "api_call",
                "website_visit")}
              tags:
                path: {$event.data.path}
                city: {$locateUser.data.city}
                country: {$locateUser.data.country}
              fields:
                elapsedTime:
                  # oneOf syntax can be useful for getting value from one
                  # of the executions that can executed `optionally` depending
                  # on the flow.
                  #
                  # for this execution we can also wait for a separate event that
                  # httpServer emit after each request completed to reduce complexity
                  # here but oneOf and ! syntax together can be useful for other cases.
                  oneOf:
                    - {$website.data.elapsedTime}
                    - {$saveArticleCreation.data.elapsedTime}
                value: 1
          
          # logRequest logs http request with additional info.
          logRequest:
            bluelogger: log
            dependsOn:
              locateUser: location
            map:
              message: new http request
              data:
                browserInfo: {$event.data.browserInfo}
                path: {$event.data.path}
                ip: {$event.data.ip}
                country: {$locateUser.data.country}
                city: {$locateUser.data.city}