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* docs: Migrate development tracking from Trello to GitHub Projects * docs: Replace non-template based references and correct templates
59 lines
2.4 KiB
Cheetah
59 lines
2.4 KiB
Cheetah
{{define "exchanges subscription" -}}
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{{template "header" .}}
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# Exchange Subscriptions
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Exchange Subscriptions are streams of data delivered via websocket.
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GoCryptoTrader engine will subscribe automatically to configured channels.
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A subset of exchanges currently support user configured channels, with the remaining using hardcoded defaults.
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See configuration Features.Subscriptions for whether an exchange is configurable.
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## Templating
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Exchange Contributors should implement `GetSubscriptionTemplate` to return a text/template Template.
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Exchanges are free to implement template caching, a map or a mono-template, inline or file templates.
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The template is provided with a single context structure:
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```go
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S *subscription.Subscription
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AssetPairs map[asset.Item]currency.Pairs
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AssetSeparator string
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PairSeparator string
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BatchSize string
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```
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Subscriptions may fan out many channels for assets and pairs, to support exchanges which require individual subscriptions.
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To allow the template to communicate how to handle its output it should use the provided directives:
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- AssetSeparator should be added at the end of each section related to assets
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- PairSeparator should be added at the end of each pair
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- BatchSize should be added with a number directly before AssetSeparator to indicate pairs have been batched
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Example:
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```{{`
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{{- range $asset, $pairs := $.AssetPairs }}
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{{- range $b := batch $pairs 30 -}}
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{{- $.S.Channel -}} : {{- $b.Join -}}
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{{ $.PairSeparator }}
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{{- end -}}
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{{- $.BatchSize -}} 30
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{{- $.AssetSeparator }}
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{{- end }}
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`}}```
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Assets and pairs should be output in the sequence in AssetPairs since text/template range function uses an sorted order for map keys.
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Template functions may modify AssetPairs to update the subscription's pairs, e.g. Filtering out margin pairs already in spot subscription.
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We use separators like this because it allows mono-templates to decide at runtime whether to fan out.
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See exchanges/subscription/testdata/subscriptions.tmpl for an example mono-template showcasing various features.
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Templates do not need to worry about joining around separators; Trailing separators will be stripped automatically.
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Template functions should panic to handle errors. They are caught by text/template and turned into errors for use in `subscription.expandTemplate`.
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{{template "contributions"}}
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{{template "donations" .}}
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{{end}}
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