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‎src/content/blog/2025/04-24-dotnet-containered-5.mdx

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---
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title: "☁️ 🤔 - Messaging between servers with RabbitMQ (Queueing)"
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title: "☁️ Agnostic - Messaging between servers with RabbitMQ (Queueing)"
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slug: cloud-agnostic-5
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tags: [software-development, dotnet, web, azure]
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date: 2025-04-24 21:20:00

‎src/content/blog/2025/04-25-dotnet-containered-6.mdx

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title: "☁️ 🤔 - Messaging between servers with RabbitMQ (Publish/Subscribe)"
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title: "☁️ Agnostic – Messaging between servers with RabbitMQ (Publish/Subscribe)"
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slug: cloud-agnostic-6
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tags: [software-development, dotnet, web, azure]
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date: 2025-04-25 21:20:00

‎src/content/blog/2025/04-25-dotnet-containered-7.mdx

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title: "☁️ 🤔 Intermezzo – Insightful spans with OpenTelemetry"
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title: "☁️ Agnostic – Intermezzo: Insightful spans with OpenTelemetry"
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slug: cloud-agnostic-7
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tags: [software-development, dotnet, web, azure]
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date: 2025-05-02 19:00:00

‎src/content/blog/2025/05-04-dotnet-containered-8.mdx

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---
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title: "☁️ Agnostic – On gremlins and graphs"
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slug: cloud-agnostic-8
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tags: [software-development, dotnet, web, azure]
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date: 2025-05-04 21:30:00
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topic: "azure-ahead"
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---
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<TopicToc
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title="Cloud agnostic series"
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topicId="azure-ahead"
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active={frontmatter.title}
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closed
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/>
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Time to look at what may be by far the most exotic technology choice in ahead: The use of a graph database
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in the form of the gremlin endpoint provided by Cosmos.
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This decision was taken about 7 years ago – a good part of it was related to my excellent
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experiences with graph databases. Microsoft was already offering said endpoint for their Cosmos DB offering,
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and after some proof of concept we went in.
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From today's perspective, I'd rather choose _boring tech&trade;_ over _superior tech&trade;_. Case in point,
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it took me quite some time to settle on what a dockerized version of ahead could use from the [list of technologies
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showcased][list-dbs] on the tinkerpop (tinkerpop the tech vs gremlin the language, I assume, although I've never been
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100% clear on where to draw the line between the two terms) page.
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Generally, the tech feels fairly far away from .NET, even though [Gremlin.NET][gremlinnet-doc] is a capable client to access
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gremlin-enabled databases.
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After some back and forth I settled for [Arcade DB][arcade]. It is a multi-model database (much like Cosmos is)
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and offers Gremlin-related capabilities, [documented here][arcade-gremlin-doc].
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## The infrastructure
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The DB is also available as container – the following code shows how the resource is registered with Aspire:
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<GHEmbed showHint repo="ahead-dockerized" branch="snapshot_2" file="AppHost/InfrastructureDependencies.cs" start={27} end={65} />
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There's a bit to unpack here:
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In Aspire, we can define a connection string also as a resource. This method will then return the Graph DB resource
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as well as the connection string necessary to connect to it as a resource as well. This is done
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in the `AppHost` project as follows:
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<GHEmbed repo="ahead-dockerized" branch="snapshot_2" file="AppHost/Program.cs" start={30} end={37} />
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<Info>
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In the code you find traces of some conditional resource building - this felt particularly useful for when
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focusing work on a specific subset of resources. If you know your system well, you may not need to start
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_all_ services to check on specific aspects of your application. Aspire will allow you to conditionally initiate
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and reference resources, since, at the end of the day, it is just c# code.
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</Info>
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We can then reference the connection string from the project that needs it. The connection string will appear
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in the system as a connect string with the name given to the resource (`GraphDbConnectionString.Name`).
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<GHEmbed repo="ahead-dockerized" branch="snapshot_2" file="Ahead.Web/Infrastructure/GraphAccess.cs" start={23} end={27} />
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Where things went awry for me is that the documentation of Arcade DB for [running it in a container][in-container] says that you should bind
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a specific folder in order to have the database files stored beyond container restarts. However, the graph db-related
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plugin defined its own specific location that was not bound to an external volume and hence all data created while
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having the solution running was lost after a restart.
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To counter this behavior I made a copy of the original properties file governing the behavior of the gremlin db plugin:
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```sh title="This command is run in the data folder"
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docker cp ahead_graphdb:/home/arcadedb/config/gremlin-server.properties ./gremlin-server.properties
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```
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And then the file is adapted for the relevant setting to point to something in the folder
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already bound for database data.
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```properties ins={2}
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gremlin.graph=com.arcadedb.gremlin.ArcadeGraph
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gremlin.arcadedb.directory=/data/graph
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```
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<br/>
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<Info>
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If you wanted to have a look into the container's file system,
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you can do an interactive session with the container like so:
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```sh
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docker exec -it ahead_graphdb sh
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```
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provided you gave it the name `ahead_graphdb`
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</Info>
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The readme of the solution contains instructions if you want to connect to the database via an interactive console.
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## The usage
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The basic abstractions to use the DB follow those that we established many years ago at ahead:
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```csharp
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public interface IAheadGraphDatabase
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{
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public Task RunJob(IGremlinJob job);
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public Task<T> RunJob<T>(IGremlinJob<T> job);
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}
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public interface IGremlinJob
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{
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Task Run(IGraphContext graphContext);
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}
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public interface IGremlinJob<T>
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{
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Task<T> Run(IGraphContext graphContext);
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}
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public interface IGraphContext
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{
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Task Run(string query);
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Task<IReadOnlyList<TOut>> Run<TIn,TOut>(Func<GraphTraversalSource,GraphTraversal<TIn,TOut>> query);
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}
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```
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This forces the packaging of database mutating & querying as _jobs_, where the constructor plays the role of accepting
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necessary parameters and the return value typically provides DTOs that are already useful for further processing.
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The `GraphTraversalSource` and other Types come from the [Gremlin.NET Nuget package][gremlin-nuget],
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that also comes with the methods to write a so-called traversal (aka query).
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<Info>
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Interestingly, I was able to use the latest version of Gremlin.NET, which is still not allowed to be used with Cosmos DB.
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This latest version allows eg to send the traversal request in a binary form, which presumably is more efficient to en- & decode than the
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usual JSON.
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</Info>
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A simple usage example is implemented in the solution in the "Graph"-page:
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<GHEmbed repo="ahead-dockerized" branch="snapshot_2" file="Ahead.Web/Pages/Graph.cshtml.cs" start={21} end={31} />
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## Conclusion
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After some searching and back & forth, I have a somewhat better feeling about how a migration could look like.
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Scaling could work with Arcade DB's clustering features or lean into things we've learned around using different
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resources for different tenants in order to support different data residencies in order to scale horizontally.
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Even so, I am still thinking how a migration to a document database could look like - simply for reasons of using even more
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_boring tech&trade;_, something a long-lived product can profit immensely from.
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[list-dbs]: https://tinkerpop.apache.org/providers.html
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[gremlinnet-doc]: https://tinkerpop.apache.org/docs/current/reference/#gremlin-DotNet
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[arcade]: https://arcadedb.com/
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[arcade-gremlin-doc]: https://docs.arcadedb.com/#gremlin-api
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[arcade-source]: https://github.com/ArcadeData/arcadedb
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[gremlin-nuget]: https://www.nuget.org/packages/Gremlin.Net
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[in-container]: https://docs.arcadedb.com/#docker
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