Item:OSWd25678c7abf9484d8e80ea5c295bb9c6
| How to use the graph tool ID: OSWd25678c7abf9484d8e80ea5c295bb9c6 | UUID: d25678c7-abf9-484d-8e80-ea5c295bb9c6 | |
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| ID | OSWd25678c7abf9484d8e80ea5c295bb9c6 |
| UUID | d25678c7-abf9-484d-8e80-ea5c295bb9c6 |
| Label | How to use the graph tool |
| Machine compatible name | HowToUseTheGraphTool |
| Types/Categories | Tutorial |
| Statements (outgoing) | |
| Statements (incoming) | |
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| Details | |
Description
A primer on how to use the graph tool in Open Semantic Lab to navigate the knowledge graph built inside the platform
Foreword
In Open Semantic Lab, all information is stored as relationships between entities. The graph tool visualizes these relationships:
- Nodes = things (pages, values)
- Edges = relationships (properties)
Exploring the graph helps you understand how data is connected.
You can find some basic information on knowledge graphs here. The knowledge graph in OSL serves as a browsable network of knowledge entries. This network is established through relationships between entries. The graph tool visualizes how things are connected.
Use the graph tool when you want to:
- understand how an entry is related to others
- explore category or schema hierarchies
- discover related entries or similar items
- With forms in OSL you create and edit entries that are used to build the knowledge graph
- A knowledge graph essentially consists of interlinked web documents. Two types of links are possible in OSL: links to internal web documents (entities) and external web documents (websites)
- Every entry in OSL contains data in several slots:
- JSON-Data and JSON-Schema slots
- Both slots contain structured information as JSON documents
- Every entry in the "Item" namespace is a member of a category:
- "Item" entries only possess a JSON-Data slot and follow the schema defined by a "Category"
- Entries in the "Category" namespace possess JSON-Data and JSON-Schema slots
- The JSON-Schema slot contains the schema that all members of this category have to adhere to
- The JSON-Data of an entry is validated against the JSON-Schema of the corresponding category when edited through the form editor
- Categories inherit parts of their JSON-Schema from super categories and define additional properties
- Forms are a rendering of the JSON-Schema of a category
- JSON-Schema is a web standard for structured documents (JSON)
- In OpenSemanticLab (OSL), JSON-Schema is combined with JSON-LD:
- JSON-LD extends JSON by providing context
- This context can contain links to other web documents, thereby connecting data
- By assigning semantic properties to JSON properties within this context, semantic triples are created
- A background engine builds the graph database from these assignments and JSON documents that adhere to the schemas
- Consult About this platform: semantic triples for more information
- The graph is built from basic building blocks called semantic triples:
- Nodes: Entries or values within OSL
- Edges: Semantic properties that connect nodes
- A semantic triple expresses a statement in the form:
- subject --predicate-> object
- Example: John Doe --isA-> Person
- Nodes can serve as subject and/or object
The following sections explain how this structure is visualized and explored using the graph tool.
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The Graph tool
The graph tool is displayed on each entry in OSL. It is located at the bottom of the page, just above the attachments section.
Example: About this platform - graph
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Basic Example: Explore the schema of any page
- Open the graph tool on a page
- Right-click the central node
- Select "HasSchema"
- A new node appears → this is the schema used
- Follow "SubClassOf" to understand its hierarchy
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Editor elements
Nodes and edges
The central node (dark green) represents the current page. It is connected to other nodes via arrows labeled with semantic properties (e.g. "HasSchema", "SubClassOf").
These connections show how the entry relates to schemas and other entities.
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Property selectors
Note: Use the property selector to hide parts of the graph to reduce complexity and focus on specific relationships.
At the bottom of the graph editor, buttons represent active semantic properties (colored like the corresponding edges).
Clicking a button toggles visibility of:
- the property
- all connected nodes
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Important:
- The Edit menu changes the actual data (semantic relationships)
- The View menu only changes how the graph is displayed
Note: Be careful when adding edges – they create actual semantic relationships and affect stored data.
With the edit menu (top left), you can create semantic statements directly in the graph:
- Add node – reference an existing OSL entry
- Add edge – create a semantic triple
To create an edge:
- Click and drag from one node to another
- Select a semantic property
The first node becomes the **subject**, the second becomes the **object**.
These statements are stored in the JSON-Data slot when clicking "Save changes".
⚠️ Without saving, changes are lost when leaving the page.
This method is useful for:
- relationships specific to individual entries
- relationships not defined in the category schema
Alternatively, you can use:
- the form editor
- the "Statements" property for structured editing
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Right-clicking on a node opens:
- A link to the corresponding page
- All semantic properties:
- outgoing (normal)
- incoming (prefixed with "-")
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Tip: How to explore efficiently
- Start with 1–2 relevant properties instead of expanding everything
- Follow relationship chains (e.g. "IsPartOf", "SubClassOf")
- Use reverse properties ("-...") to find related entries
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Clicking a property expands the graph by showing connected nodes. This can be repeated to follow chains and explore relationships.
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Example: Exploring relationships
To reproduce the example:
- Right-click "About this platform" → select "IsPartOf"
On the node "OpenSemanticLab for end users":
- Select "IsPartOf" → move upward in the hierarchy
- Select "-IsPartOf" → see related entries
From there:
- Expand "HasSchema" → see the entry type ("Article")
- Follow "SubClassOf" → explore class hierarchy
You will observe:
- "SubClassOf" chains lead to "Entity" (most general category)
- All entries ultimately belong to "Entity"
- Categories define shared properties
- Subcategories add more specific properties
Exploring these chains helps you understand:
- how entries are structured
- how categories relate to each other
- how knowledge is organized in OSL
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Exploration tip: Expand a property chain up to a meaningful level (e.g. a Category), then explore reverse properties ("-...") to find similar or related entries.
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Note: The View menu only changes how the graph is displayed (it does NOT modify data).
On the top right, you can:
- Reset the view → restore default or saved layout
- Copy permalink → share the current graph view
- Save changes → store the current layout
Use this to:
- create reusable views
- share specific graph perspectives with others
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Go ahead and explore the graph yourself!
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