A service level contract is an agreement between two or more parties, one being the customer and other service providers. It may be a formal or informal legally binding “treaty” (for example. B internal relations within the department). The agreement may include separate organizations or different teams within an organization. Contracts between the service provider and other third parties are often referred to as SLAs (wrongly) – the level of service having been set by the (main) customer, there can be no “agreement” between third parties; these agreements are simply “contracts.” However, operational agreements or olea agreements can be used by internal groups to support ALS. If an aspect of a service has not been agreed with the customer, it is not an “ALS.” A Service Level Contract (SLA) is an obligation between a service provider and a customer. Specific aspects of the service – quality, availability, responsibilities – are agreed between the service provider and the service user.  The most common component of ALS is that services are provided to the client in accordance with the contract. For example, internet service providers and telecommunications companies will generally include service level agreements under the terms of their contracts with customers to define service levels of service level sold in plain language. In this case, ALS generally has a medium-time technical definition between errors (MTBF), average repair time or average recovery time (MTTR); Identifying the party responsible for reporting errors or paying royalties; Responsibility for different data rates throughput; Jitter; or similar measurable details.
Because applications are moved from dedicated hardware to the cloud, they must reach the same level of service, or even more sophisticated than conventional installations. SLAs for cloud services focus on data center features and more recently include network features (see Carrier`s Cloud) to support end-to-end SLAs.  A Web Service Level Agreement (WSLA) is a standard for monitoring compliance with web services under service level agreements. It allows authors to indicate performance metrics assigned to a web application, desired performance goals, and actions to perform if performance is not achieved. Many SLAs follow the specifications of the Information Technology Infrastructure Library when applied to IT services. Uptime is also a common metric that is often used for data services such as shared hosting, virtual private servers and dedicated servers. General agreements include network availability percentage, operating time, number of planned maintenance windows, etc. Cloud computing is a fundamental advantage: shared resources, supported by the underlying nature of a common infrastructure environment. SLAs therefore extend to the cloud and are offered by service providers as a service-based contract and not as a customer-based agreement. Measuring, monitoring and covering cloud performance is based on the final UX or its ability to consume resources. The disadvantage of cloud computing compared to ALS is the difficulty of determining the cause of service outages due to the complex nature of the environment. The main point is to create a new level for the grid, cloud or SOA middleware, capable of creating a trading mechanism between service providers and consumers.
For example, the EU-funded Framework SLA@SOI 7 research projectexplores aspects of multi-level, multi-supplier slas within service-based infrastructure and cloud computing, while another EU-funded project, VISION Cloud, has delivered results in terms of content-based ALS.