I'm trying to write microservices in Java. I've implemented GraphQL endpoints using graphql-spring-boot-starter.
Now I have a problem how to make it efficient.
Datamodel is like a tree and I need to query for data from multiple services at once. The problem is how to filter for a member of collection, something like CONTAINS in database, but data is not in separate table, but separate microservice. Maybe the problem is that domain is not correctly splitted between services?
Let's make an example: I have 3 microservices: users, libriaries, books. Every library have collection of users and books (just list of identifiers, like foreign keys). Every book has a name and genre. Every library have lists of books borrowed by user (identifiers too).
Question 1 - should library hosts list of books and users (just identifiers, like foreign keys)? Is it correct approach?
Question 2 - I want to find libraries in which specified users (by surname) have borrowed books of specified genre. Going from top I need to first find libraries containing users. Not easy, as we have names in different service. We need to query first for users, gathers their identifiers, and now we are able to query for libraries. But it isn't all. Now we need to find books for every user and check genres - in different service. And it's not all. I want to have everything presented in nice way, so whole output should be sorted and paged. It force me to collect all data from all services, then page and sort it, which of course will not be efficient.
Please don't concentrate on this example, I'm looking how to solve general approach, not this one example. I've tried to use Datafetchers but it's troublesome and there are not good examples of calling Graphql-to-GraphQL. Most examples covers calling REST endpoints etc.
Related
I'm playing around with a workout app (android), and want to match workouts to dates. The basic structure is :
Each date has zero or one workouts.
Each workout has one or more exercises.
Each exercise has a name, and one or more sets.
Each set has a weight, and one or more repetitions.
I'm considering a json file, where:
Each date attribute has a list of exercise objects.
Each exercise object has a name, and a list of set objects.
Each set object has a weight attribute and a repetitions attribute.
Thoughts?
If you are doing it with Android, use clases to represent the different entities you have mentioned.
To persist the information inside the phone, I sugest you use the built in sqlite database.
If you plan to build the app as the front end for a rest api or webservice, then yes you can use a json file to exchange informtion with the server. Now, on the server, you would persist the data in a database of your choice. I would go with a relational database like mysql, but for the model you are proposing it would be feasable to also go with a Nosql alternative.
I want to create a membership based site in Umbraco 7, following the umbraco.tv videos and reading through the docs have got me quite far.
My members will have custom properties, firstname, lastname, favourite colours, hats owned etc. I have been adding each of these as custom properties and then assigning them to the tab I want. This works fine and I can then access them from code using:
Members.GetCurrentMember().GetProperty("lastname").Value.ToString();
When I looked in my database I noticed that each of these custom properties is a row in the cmsPropertyData table, linked to the cmsMember table by the nodeId column. Is there a way I can set all of this information to store in it's own table?
Ideally, I want each Member to have a one to many relationship with favourite colours, as well as one to many relationships with other tables; each member might have 100 hats for example. What is the best way for me to set this up? Shall I create custom tables in my Umbraco database for HatsOwned and FavouriteColours, then assign each Member a unique ID so I can set my foreign keys up correctly? That way I would only need to store the Members Unique Id in the cmsPropertyTable. Is there a better way to let Umbraco deal with it? Would I have difficulty retrieving Members using either the Umbraco orm, or EF?
Any help or pointers greatly appreciated!
I would store all data in the PROFILE of the member, in the umbraco membership. E.g. timezone, hair color, ... This makes sense for other developers to find back the data.
For all other data, you have a few options:
Relationships
If you want to link nodes to members, or nodes to nodes, or... Relations link 2 umbraco entities and can be one way or two way. If you have a color node, you can link all members to this node. Just create a "favoriteColor" relationship on the developer section, linking up nodes to members. Do some programming and you are done. Don't forget that a relation is a database record linking 2 umbraco entities. So think of some caching if you use this in your front end to take off some database load. Read more on the Relationship Api in the umbraco documentation.
Content
It's pretty easy to create new nodes using code to store e.g. comments on an article. Because you are republishing the xml cache every time you create (and publish) a node, don't use content nodes for stroring your data if you have a lot of updates.
External data
It is perfectly legit to store data outside of umbraco. Just create your own tables (or content to any service you created). You could use every ORM you want to, but I would recommend PetaPoco. The reason is obvious. Umbraco uses it also. And it will make you a better Umbraco developer. There is a detailed post on stackoverflow on how to work with external data in umbraco.
In my project we define threats/risks and countermeasures. I want to keep track and refer to both types of entities in Sphinx, as well as generating a list of both threats/risks and the countermeasures. Let's say I have 30 risks and 50 countermeasures (many-to-many relationship).
I'd be happy just to have a lists of both and the ability to refer to each other by numbers (e.g. "risk #23", "countermeasure #12"). It would be even better if the system could display the relationship automatically.
The content of both is let's say a single paragraph or even shorter, so that's why I dislike to use regular headings. And I cannot refer to items in lists or table rows. So, I'm looking for something like a Figure in Sphinx (numbered, with caption), but then for arbitrary types of entities.
My current approach is to create a custom RST role for this. Is this the right approach? If so, where to start?
So just getting started with Azure tables- haven't played with them before so wanted to check it out.
My understanding is that I should be thinking of this as object storage, rather than a database, which is cool. But I'm a bit confused on a couple points...
First, if I have one to many object relationships, what should the partitionkey of the root object look like? For example, let's say I have a University object, which is one to many to Student objects, and say Student objects are one to many to Classes. For a new student, should its partitionkey be 'universityId'? Or 'universityId + studentId'? I read in the msdn docs that the RowKey is supposed to be an id specific to the item I am adding, which also sounds like studentId.
And then would both the partitionkey and rowkey for a new University just be universityId?
I also read that Azure Tables are not for storing lists- I take it that does not refer to storing an object that contains a List...?
And anyone have any links to code samples using asp mvc 3 or 4 and razor with azure tables? This is my end goal, would be cool to see what someone who actually knows what they are doing does :)
Thanks!
You're definitely right that Azure Tables is closer to an object store than a database. You do have some ability to query on non-key columns, and to do logic in queries. But you shouldn't plan on using those features for anything performance critical.
Because queries are only fast if you specify at least a PartitionKey (and preferably a RowKey or range or RowKeys) that heavily influences how you lay out your tables. The decisions you make at the beginning will have big performance implications later. As a rough analogy, I like to think about them like a SQL Server table with the primary key as (PartitionKey + RowKey), that can never have another index. That's not completely accurate, but it'll get you thinking in the right direction.
First, if I have one to many object relationships, what should the partitionkey of the root object look like?
I would probably use the UniversityId as the PartitionKey. That's generally a safe place to start.
For a new student, should its partitionkey be 'universityId'? Or 'universityId + studentId'?
How do you plan to query the students? If you're always going to have their UniversityId & StudentId I would probably make them the PartitionKey and RowKey, respectively. If you're mostly going to query based on StudentId, I would use that as the PartitionKey instead.
would both the partitionkey and rowkey for a new University just be universityId?
That's a viable choice. You can also use a constant value (eg "UNIVERSITY") for the RowKey, if you've really got nothing else to put there.
I also read that Azure Tables are not for storing lists- I take it that does not refer to storing an object that contains a List...?
I'm not entirely sure what that means. Clearly you can store a collection of objects in a table, that's what they're for. You can't directly store a list in an entity property. So if your Student has a property of typee List, that can't be stored directly. But you could serialize it to XML or binary, and store that.
I don't have any code samples handy, unfortunately. This may be a good time to abstract your data logic into its own layer, rather than putting it in your MVC controllers. We've found that a well-abstracted data layer can make unit testing your logic very easy. If you create some interfaces for your tables, it's very easy to create mock objects using just a List and some LINQ.
I'm about to embark on a project where a user will be able to create their own custom fields. MY QUESTION - what's the best approach for something like this?
Use case: we have medical records with attributes like first_name, last_name etc... However we also want a user to be able to log into their account and create custom fields. For instance they may want to create a field called 'second_phone' etc... They will then map their CRM to their fields within this app so they can import their data.
I'm thinking on creating tables like 'field_sets (has_many fields)', 'fields', 'field_values' etc...
This seems like it would be somewhat common hence why I thought I would first ask for opinions and/or existing examples.
This is where some modern schemaless databases can help you. My favourite is MongoDB. In short: you take whatever data you have and stuff a document with it. No hard thinking required.
If, however, you are in relational land, EAV is one of classic approaches.
I have also seen people do these things:
predefine some "optional" fields in the schema and use them if necessary.
serialize this optional data to string (using JSON, for example) and write it to text blob.