What is a mock service?

Mock service is a software tool that simulates the behavior of a service in a controlled environment. It allows developers to test the behavior of their client applications without the need for a real server.

A mock service allows developers to test their client applications by providing fake responses to method calls. This is useful for testing the client-side code in isolation, without the need for a real server to be running. It also allows developers to simulate different scenarios and test edge cases that might be difficult or impossible to reproduce in a real environment.


gRPC (short for "Google Remote Procedure Calls") is a high-performance, open-source universal RPC framework that uses HTTP/2 as the underlying transport. It enables developers to build fast, efficient, and scalable distributed systems by defining service interfaces in a simple interface definition language (IDL) and generating client and server stubs in a variety of programming languages.

gRPC uses HTTP/2 as the underlying transport protocol and relies on a binary encoding of messages, called Protocol Buffers, to serialize and transmit data between client and server. This allows gRPC to achieve high performance and low latency, as well as to support streaming and bi-directional communication.

gRPC is suitable for a wide range of applications, including microservices, cloud-native applications, and mobile apps. It has support for many programming languages and platforms and can be used with a variety of deployment environments, including containers and cloud environments.


gRPC-Web is a JavaScript library that allows web applications to communicate with gRPC servers using standard HTTP 1.1. It is an extension of the gRPC protocol that enables gRPC messages to be sent and received over the web, using the same interface as regular gRPC calls.

gRPC-Web is useful for building web applications that need to communicate with backend gRPC services in a fast and efficient manner. It is especially useful for applications that require low-latency communication, such as real-time messaging or streaming data.

To use gRPC-Web, you will need to have a gRPC server running on the backend and a gRPC-Web client library in the frontend. The client library communicates with the gRPC server using a gRPC-Web proxy, which translates the HTTP 1.1 requests and responses into gRPC messages.

gRPC Transcoding

gRPC Transcoding is a feature of the gRPC framework that allows a gRPC server to accept incoming requests in a different format, such as HTTP/JSON, and convert them into gRPC requests that can be handled by the server. This allows clients that do not natively support gRPC to communicate with a gRPC server, by using a supported format as an intermediate step.

gRPC Transcoding is typically implemented by a reverse proxy or gateway that sits between the client and the gRPC server. The reverse proxy converts the incoming request into the format expected by the gRPC server and then passes the request on to the server. The reverse proxy also converts the gRPC server's response back into the format expected by the client before returning it to the client.

gRPC Transcoding can be useful in situations where it is not practical or feasible for clients to support gRPC directly, but the benefits of using gRPC, such as high performance and efficient use of network resources, are still desired. It can also be used to allow legacy systems or clients to communicate with gRPC servers without the need to modify the client software.


HTTP (short for "Hypertext Transfer Protocol") is a networking protocol used for transmitting data over the web. It is the foundation of the modern web and is used by almost all websites and web-based applications to communicate with servers and transmit data.

HTTP is a request-response protocol, which means that a client (such as a web browser) sends a request to a server, and the server sends back a response. The request and response messages are formatted according to the HTTP specification, which defines the structure and content of the messages as well as the rules for exchanging them.


REST (Representational State Transfer) is a software architectural style that defines a set of constraints for designing web services. REST is based on the idea of representing the state of a resource in a distributed system, and it is designed to be simple, scalable, and flexible.

RESTful web services are built around the principles of REST, and they use the HTTP protocol to provide a standard way of accessing and manipulating resources over the internet. RESTful web services use a set of HTTP methods, such as GET, POST, PUT, and DELETE, to perform actions on resources, and they use HTTP status codes to indicate the success or failure of these actions.

REST is widely used for building web services, and it is often preferred over other approaches, such as SOAP (Simple Object Access Protocol) because it is simpler to implement and more flexible. RESTful web services are also easy to scale and integrate with other systems, which makes them well-suited for use in modern, distributed systems.


An endpoint is a network address that is used to communicate with a server. It consists of a hostname or IP address and a port number, and it defines the location of the server on the network.


YAML (Yet Another Markup Language) is a human-readable data serialization language that is designed to be easy to read and write. It is commonly used for storing and exchanging data in a hierarchical structure, such as in configuration files and application data.

YAML is based on the concepts of key-value pairs and indentation, which allows it to represent complex data structures in a simple and concise way. It uses a series of punctuation characters and special syntax to define the structure of the data, such as the use of colons to separate keys and values, and dashes to indicate lists.

YAML is often used in combination with programming languages, as it provides a simple and flexible way to represent data in a structured format. It is also used as a configuration language for a variety of applications, including web servers, databases, and continuous integration systems.


JSON (short for "JavaScript Object Notation") is a lightweight data interchange format that is used to transmit data between systems. It is based on a subset of the JavaScript programming language, and it is designed to be easy for humans to read and write and easy for machines to parse and generate.

JSON is a text-based format that represents data in a structured way, using key-value pairs to represent data elements. It is commonly used to transmit data over the internet, and it is supported by a wide range of programming languages and platforms.

JSON is often used to transmit data in web applications, and it is also used in many other contexts, such as configuration files, log files, and APIs. It is a popular choice for data interchange because it is simple, easy to read and write, and easy to parse and generate.


Protocol Buffers (protobuf) is a language- and platform-neutral data serialization format developed by Google. It is used to encode structured data in a compact binary format that is efficient to transmit and process.

Protobuf is designed to be extensible, scalable, and easy to use. It is based on a simple, statically-typed language for defining data structures, and it uses compact binary encoding to represent data in a more efficient way than text-based formats like JSON or XML.

Protobuf is often used in distributed systems to transmit data between systems, and it is also used in a variety of other contexts, such as configuration files, log files, and APIs. It is a popular choice for data serialization because it is efficient, extensible, and easy to use.


Authentication is the act of proving an assertion, such as the identity of a computer system user. In contrast with identification, the act of indicating a person or thing's identity, authentication is the process of verifying that identity. It might involve validating personal identity documents, verifying the authenticity of a website with a digital certificate, determining the age of an artifact by carbon dating, or ensuring that a product or document is not counterfeit.

Bearer authentication

Bearer authentication, also known as token-based authentication, is a method of authenticating a client (such as a web browser or application) by sending a token in the "Authorization" header of an HTTP request.

In bearer authentication, the client obtains a token from an authentication server and includes it in the "Authorization" header of subsequent requests to the server. The token is a digitally signed and encoded value that contains information about the client, such as its identity, privileges, and other relevant details.


Authorization is the process of giving someone permission to do or have something. In multi-user computer systems, a system administrator defines the system to which users are allowed access to the system, and what privileges of use (such as access to which file directories, hours of access, amount of allocated storage space, and so forth). Assuming that someone has logged in to a computer operating system or application, the system or application may want to identify what resources the user can be given during this session. Thus, authorization is sometimes seen as both the preliminary setting up of permissions by a system administrator and the actual checking of the permission values that have been set up when a user is getting access.

Logically, authorization is preceded by authentication.

URL path

The path is the part of the URL that specifies the specific resource being requested. It typically follows the domain name and is separated from it by a forward slash (/). For example, in the URL "", the domain name is "" and the path is "/path/to/resource". The path can be further broken down into subdirectories and file names, depending on the specific resource being requested.

For example, the path "/path/to/resource" could refer to a directory called "path" that contains a subdirectory called "to", which in turn contains a file called "resource". The path can also refer to a specific file or resource located directly in the root directory of a website, in which case it would not contain any subdirectories.

URL query

The query is the part of the URL that contains data to be passed to a web application or resource. It is typically separated from the rest of the URL by a question mark (?) and consists of a series of key-value pairs, each separated by an equal sign (=) and each pair separated by an ampersand (&).

For example, consider the following URL:

In this URL, the domain name is "" and the path is "/search". The query consists of two key-value pairs: "q=example" and "page=2". The key "q" is associated with the value "example", and the key "page" is associated with the value "2".

Queries are often used to specify search terms, sort order, filters, and other parameters that control the behavior of a web application or resource. They can be passed to a server via the HTTP GET method, which appends them to the end of the URL as a query string.


A wildcard is a symbol that can be used to represent one or more characters in a match. In computer programming and database management, wildcards are often used to search for or match data that may have different variations or that is not known in advance. For example, you could use a wildcard to search for all files with a certain extension or to match all data that begins with a certain letter.

  • '*' matches 0 or more characters
  • '?' matches 1 character

Regular expression

A regular expression (also called a regex or regexp) is a sequence of characters that defines a search pattern. Regular expressions are typically used to search for specific patterns of characters in text or to perform some kind of transformation or manipulation of text data.

Regular expressions are composed of characters and special symbols that represent different types of pattern matching. For example, the dot (.) symbol can be used to match any single character, the asterisk (*) symbol can be used to match zero or more characters, and the question mark (?) symbol can be used to match zero or one character. Square brackets ([ ]) can be used to specify a range of characters to match, and special symbols like \d, \w, and \s can be used to match digits, word characters, and white space, respectively.

Learn more:


JPath is a syntax for specifying paths through a JSON document. It is similar to XPath, which is a syntax for specifying paths through an XML document.

JPath is often used to extract specific data from a JSON document or to navigate through the structure of the document. It uses a combination of keys, array indices, and wildcard characters to specify the path to the desired data.

Learn more:

Scalar property

In Protocol Buffers (protobuf), a scalar property is a property that can hold a single value of a specific data type. Protobuf supports several scalar data types, including integers, floating-point numbers, booleans, and strings.

Scalar properties are the most basic type of property in protobuf, and they are used to store simple data values. They are typically used in combination with more complex types of properties, such as repeated properties and nested properties, to define more complex data structures.

Sequence property

In Protocol Buffers (protobuf), a repeated property is a property that can hold a sequence of values of a specific data type. A repeated property is defined using the "repeated" keyword followed by the data type and the property name.

Repeated properties are useful for representing lists of data in a protobuf message. They can be used to store any number of values, including zero values, and they can be accessed and modified like any other array in a programming language.

Repeated properties can be nested within other types of properties, including other repeated properties and message properties, to create more complex data structures. They can also be used in combination with scalar properties and message properties to define more advanced protobuf messages.

Complex property

In Protocol Buffers (protobuf), a complex property is a property that holds a nested data structure. A complex property can be either a message property or a group property.

A message property is a property that holds a nested message as its value. Message property is defined using the "message" keyword followed by the message name and the property name.

Complex properties are useful for representing nested data structures and for organizing fields within a protobuf message. They can be nested within other complex properties or scalar properties to create more complex data structures. They can also be used in combination with repeated properties to define even more advanced protobuf messages.

HTTP Headers

HTTP headers let the client and the server pass additional information with an HTTP request or response. An HTTP header consists of its case-insensitive name followed by a colon (:), then by its value. Whitespace before the value is ignored.

HTTP Response Trailer

Trailer The Trailer response header allows the sender to include additional fields at the end of chunked messages in order to supply metadata that might be dynamically generated while the message body is sent, such as a message integrity check, digital signature, or post-processing status.

Certificate chain

A certificate chain, also known as a certificate path, is a series of digital certificates that are used to establish the trustworthiness of a particular certificate. It is used to verify that a certificate has been issued by a trusted authority and that it has not been tampered with.

A certificate chain typically consists of a root certificate at the top, followed by one or more intermediate certificates, and finally the target certificate at the bottom. The root certificate is issued by a trusted certificate authority (CA) and is used to establish trust in the entire chain. The intermediate certificates are issued by the root CA or by other intermediate CAs and are used to establish trust in the target certificate. The target certificate is the certificate that is being validated and issued by an intermediate CA.

To validate a certificate chain, a client (such as a web browser or application) will start at the bottom with the target certificate and work its way up the chain, verifying the signatures on each certificate and ensuring that the issuer of each certificate is trusted. If the chain is valid, the client can trust the target certificate and use it to establish a secure connection with a server or to authenticate a user.

Certificate thumbprint

A certificate thumbprint, also known as a certificate fingerprint, is a unique identifier that is associated with a digital certificate. It is used to uniquely identify a certificate and to verify that it has not been tampered with.

A certificate thumbprint is typically created by running a hash function on the certificate's public key and other identifying information. The resulting hash value, known as the thumbprint, is a fixed-length string of characters that is unique to the certificate.

Liquid template

Liquid is a template language that is used to generate dynamic content for websites and other applications. It is commonly used in conjunction with web frameworks such as Ruby on Rails and Jekyll and is also used by platforms such as Shopify to enable users to customize the appearance and content of their online stores.

Liquid templates consist of a combination of text and Liquid tags, which are enclosed in curly braces (e.g. {{ tag }}). The Liquid tags contain instructions that tell the template engine what to do, such as iterating over a collection of objects, displaying a value from a data source, or making decisions based on certain conditions.

Liquid templates are often used to display dynamic data on a website or application, such as product listings or user profiles. They allow developers to create templates that can be reused and customized easily, without the need to write separate HTML or code for each page or component.